East Cambridgeshire District Council Water Cycle Study Detailed ...

East Cambridgeshire District Council 

Water Cycle Study 

Detailed Study: Stage 2 Report 

Final Report 

September 2011 

Prepared for

Revision Schedule 

Stage 2: Detailed Water Cycle Study 

Sept 2011 

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© Scott Wilson Ltd 2011 

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Cambridgeshire Horizons 

East Cambridgeshire – Detailed WCS 

Rev Date Details Prepared by Reviewed by Approved by 

01 February 

2011 

Draft Structure 

for comment 

Clare Postlethwaite 

Senior Consultant 

02 May 2011 Draft_V2 Clare Postlethwaite 


Amy Ruocco 

Graduate Water 

Specialist 

03 July 2011 Draft_V3 Clare Postlethwaite 


Amy Ruocco 


Specialist 

04 Aug 2011 Final Draft (v4) Clare Postlethwaite 


Amy Ruocco 


Specialist 

05 Sept 2011 Final report Clare Postlethwaite 


Amy Ruocco 


Specialist 

Dr James Riley 

Principal Biodiversity 

Specialist 

Carl Pelling 

Principal Consultant 

Carl Pelling 


Carl Pelling 


Carl Pelling 


Carl Pelling 


www.urs-scottwilson.com 

Carl Pelling 


Jon Robinson 

Technical Director 

Carl Pelling 


Jon Robinson 

Technical Director 

The front cover photographs are as follows top left: Soham Lode © Copyright Bob Jones and licensed for reuse under 

the Creative Commons Attribution-Share Alike 2.0 Generic Licence; top right sewage treatment works (taken by URS 

Scott Wilson); bottom left Hod Fen © Copyright Michael Trolove and licensed for reuse under the Creative Commons 

Attribution-Share Alike 2.0 Generic Licence; bottom right Wicken Fen © Copyright Rob Noble and licensed for reuse 

under the Creative Commons Attribution-Share Alike 2.0 Generic Licence.

Table of Contents 



Executive Summary................................................................................... 1 

The Wastewater Strategy ............................................................................................................. 1 

The Water Supply Strategy .......................................................................................................... 3 

Surface Water Drainage Management ......................................................................................... 5 

Ecological Opportunities............................................................................................................... 5 

Water Cycle Strategy Recommendations and Policy.................................................................... 5 

Glossary of Acronyms and Abbreviations ............................................... 9 

1 Introduction ................................................................................... 12 

1.1 Study Need and Drivers................................................................................................ 12 

1.2 WCS Reporting............................................................................................................. 12 

1.3 Stage 2 - Study Governance......................................................................................... 13 

1.4 Stage 1 Outline WCS – Key Findings ........................................................................... 13 

1.5 Study Visions and Drivers............................................................................................. 16 

1.6 Water Use – Key Assumption ....................................................................................... 18 

2 Proposed Growth .......................................................................... 19 

2.1 Preferred Growth Strategy............................................................................................ 19 

2.2 Housing ........................................................................................................................ 19 

2.3 Employment.................................................................................................................. 21 

3 Detailed Wastewater Strategy ...................................................... 24 

3.1 Stage 1 Conclusions..................................................................................................... 24 

3.2 Wastewater Treatment Options Assessment ................................................................ 24 

3.3 Ecological Appraisal ..................................................................................................... 44 

3.4 Wastewater Networks................................................................................................... 54 

4 Water Supply Strategy .................................................................. 63 

4.1 Introduction................................................................................................................... 63 

4.2 The Vision .................................................................................................................... 63 

4.3 Ecological Appraisal ..................................................................................................... 66 

4.4 Water Neutrality Pathway ............................................................................................. 67 

4.5 Water Supply and Climate Change Adaptation............................................................. 98 

5 Surface Water Management ....................................................... 100 

5.1 The Vision .................................................................................................................. 100 

5.2 Justification................................................................................................................. 100 

5.3 Options for Surface Water Management..................................................................... 101 

5.4 Development site requirements .................................................................................. 105



5.5 Climate Change Analysis............................................................................................ 105 

5.6 Financial cost of SuDS ............................................................................................... 114 

5.7 Best Practice Examples.............................................................................................. 115 

5.8 Adoption and maintenance of SuDS ........................................................................... 116 

5.9 Conclusions................................................................................................................ 119 

5.10 Recommendations...................................................................................................... 119 

6 Potential Growth Area Infrastructure requirements ................. 120 

6.1 Ely Potential Development Areas................................................................................ 121 

6.2 Soham Potential Development areas.......................................................................... 123 

6.3 Littleport Potential Development Areas....................................................................... 125 

6.4 Bottisham Potential Development areas ..................................................................... 127 

6.5 Burwell Potential Development areas ......................................................................... 128 

7 Water Cycle Strategy Recommendations and Policy ............... 130 

7.1 Policy Recommendations Overview............................................................................ 130 

7.2 Climate Change and the Water Cycle – Adaptation .................................................... 132 

7.3 Developer Guidance................................................................................................... 133 

7.4 Further Recommendations ......................................................................................... 133 

Appendices............................................................................................. 135

Executive Summary 

Stage 2 Water Cycle Study: Final Report 

Sept 2011 

1 



The district of East Cambridgeshire is expected to experience a significant increase in housing and 

employment provision over the period to 2031. This growth represents a challenge in ensuring that both 

the water environment and water services infrastructure has the capacity to sustain this level of growth and 

development proposed. 

A joint Outline Water Cycle Study (WCS) was completed with Fenland District to determine constraints that 

may be imposed by the water cycle in both districts. A further Detailed (Stage 2) WCS has been 

completed for East Cambridgeshire based on preferred broad growth areas identified in the Council’s 

adopted Core Strategy, and a number of potential areas identified in the Ely, Soham and Littleport 

Masterplans. 

This information has been used to determine how the water cycle constraints identified in the Outline WCS 

may relate to potential development sites within the settlements, if and how the constraints can be resolved 

and how they may impact on phasing of development over the plan period. Furthermore, it provides a 

more detailed suggested approach to the management and use of water which demonstrates ways to 

ensure that the sustainability of the water environment in the study area is not compromised by growth. 

A Detailed Water Cycle Strategy is presented for the District as a whole and for each of the main growth 

settlements. 

The Wastewater Strategy 

Wastewater Treatment 

The Detailed study has shown that several Wastewater Treatment Works (WwTWs) have capacity to 

accept wastewater flow from proposed growth without the need for improvements to treatment 

infrastructure. This is the case for Isleham, the Newmarket fringes, Stretham, Wilburton, Ely and Mepal. 

Growth is not constrained by wastewater treatment in these locations. 

At the remaining WwTWs, improvements are required in order to accommodate the growth to ensure that 

the increased wastewater flow discharged does not impact on the current quality of the receiving 

watercourses, their associated ecological sites and also to ensure that the watercourses can still meet with 

legislative requirements. 

The improvements required at WwTWs in Soham, Haddenham, Witchford, Littleport, Little Downham and 

Witcham are achievable over the plan period within the limits of conventionally applied technology and 

hence, a solution can be implemented to allow growth in these catchments to proceed. Initial development 

may need to be restricted whilst improvements are implemented at these works, but assuming upgrades 

are completed, there should be no restriction on growth in the medium to long term in these locations as a 

result of wastewater treatment capacity. 

However, the detailed assessments have shown that improvements beyond conventionally applied 

technology are required at both Burwell and Bottisham WwTW (due to water quality). Early phasing of 

development in these locations may need to be restricted until solutions are developed. The WCS has 

concluded that the study partners, including East Cambridgeshire District Council, the Environment 

Agency, the Ely Group of Drainage Boards and Anglian Water should work together to determine if any of 

the potential solutions proposed in the Detailed study are acceptable and hence conclude when and how 

much development can be accommodated in Burwell and Bottisham. 

In all cases, the assessments have shown that the ability of watercourses to meet future water quality 

targets (Good Status) under the Water Framework Directive will not be compromised by growth alone and


Sept 2011 

2 



hence growth should not be seen as a barrier to watercourses in the District meeting ‘Good Status’ in the 

future. 

Ecological impacts on Designated Sites 

There are three statutory designated sites which were identified in the outline WCS as being connected to 

WwTW discharges in East Cambridgeshire – Wicken Fen SAC/Ramsar site/SSSI/LNR, Ouse Washes 

SAC/SPA/Ramsar site/SSSI and Cam Washes SSSI. There is one County Wildlife Site (New River/Monks 

Lode) which is linked to a wastewater treatment works. 

Wicken Fen SAC/Ramsar site/SSSI/Local Nature Reserve 

Burwell WwTW discharges to the Catchwater Drain which itself drains to Burwell Lode. Wicken Lode flows 

into Burwell Lode at the south-west corner of Wicken Fen. It is theoretically possible for water to backflow 

from Burwell Lode into Wicken Lode, but the EA in their RoC considered this a low eventuality. There is 

thus no evidence on which to conclude that discharges to Burwell Lode associated with the increase in 

discharges from Burwell WwTW will have any impact on Wicken Lode or Wicken Fen. 

Cam Washes SSSI 

Burwell Lode joins Reach Lode approximately 1km upstream of the River Cam which is the watercourse 

into which Reach Lode drains. The Cam Washes are offline meadows which depend upon seasonal 

inundation from the River Cam to maintain their ornithological interest. Burwell and Bottisham WwTW’s will 

both require changes (or a new solution) to their discharge consents to ensure ‘no deterioration’ in the 

quality of the receiving watercourses as a result of the increased discharge volumes from each WwTW. 

However, given that Burwell WwTW and Bottisham WwTW make a relatively small contribution to 

phosphorus loads in the downstream River Cam, it is reasonable to conclude that the upgrades necessary 

to achieve ‘no deterioration’ in the receiving watercourse should adequately address the WwTW’s 

individual contribution to phosphorus loading in the River Cam. 

New River/Monks Lode County Wildlife Site 

Monks Lode contains a number of fish species including spined loach, bitterling, bream, dace, eel, perch, 

roach and pike. The Outline Water Cycle Study identified a potential connection between discharges of 

Burwell WwTW and the New River via Catchwater Drain which is the receiving watercourse for the WwTW. 

Further scrutiny for the Detailed WCS has identified that the prevailing direction of flow will in fact prevent 

significant backflow into the New River and there is thus no evidence of a connection between Burwell 

WwTW and Monks Lode. 

Ouse Washes SAC/SPA/Ramsar site/SSSI 

The EA RoC process concluded in the Stage 4 Report that ‘the water quality in the Hundred Foot Drain is 

dominated by the water quality upstream of Earith in the Bedford Ouse Catchment. Phosphate 

concentrations do not increase along the course of the Hundred Foot River, suggesting that inputs from the 

STWs in the East Cambridgeshire study area are having little or no effect on water quality within this 

watercourse. In addition the connection between the Hundred Foot River and the designated SAC rivers is 

limited meaning water quality in the Hundred Foot River is unlikely to significantly influence the Old 

Bedford Ouse’. The RoC therefore ultimately concluded that there was no amendment required to the 

existing consents. The current evidence therefore does not indicate that existing phosphate discharges 

from the WwTWs in East Cambridgeshire are likely to be having an adverse effect upon the Ouse Washes 

SAC/SPA or SSSI. 

Before changes to the consents for relevant WwTWs are made, it is necessary to determine which 

WwTWs that discharge to tributaries of the Hundred Foot River are likely to require changes to their 

consented discharge volumes and quality standards and whether this will result in a change to the existing


Sept 2011 

3 



situation. It has not been possible as part of this study to determine the actual change in phosphate 

concentration in the Hundred Foot River which will result from the specific WwTW improvement schemes 

and thus to provide any detailed analysis of the resulting ecological effect. These matters must therefore 

be modelled in fuller detail as part of the process of securing amendments to the discharge consents for 

each relevant WwTW. 

Ecology outside designated sites 

In addition to impacts on designated sites, a range of other UK or Cambridgeshire BAP species or 

otherwise protected/notable species that are found in Cambridgeshire can be affected by wastewater 

discharge. Of the two WwTWs in East Cambridgeshire that will require a change to their consents in order 

to comply with the Water Framework Directive requirements for no deterioration downstream, Burwell 

discharges to the Burwell Lode while Bottisham discharges to Swaffham Bulbeck Lode. Both WwTWs will 

require novel treatment solutions. These will need to take into account ecological impacts on these species 

and others using the receiving watercourses as part of any planning application associated with expansion 

proposals. 

Flood risk calculations are only available for three WwTW’s covered by the Detailed WCS – Burwell, 

Soham and Bottisham due to an absence of flow and/or cross-sectional data for other receiving 

watercourses. For the three WwTW’s included, it is shown that on average flood flows will only increase by 

0.1 -2.5% as a result of these effluent discharges. It is unlikely that such small increases will cause flooding 

issues. 

Sewer Capacity 

In order to ensure wastewater from growth can be drained to the WwTWs, an assessment of sewer 

capacity constraints on potential growth sites was undertaken. This assessment has determined where 

developers will need to contribute to upgrades to existing sewerage infrastructure (sewer mains or 

pumping stations) or towards new infrastructure. 

The majority of development sites in Littleport will either need to fund upgrades or construction of new 

infrastructure, or will need to check whether capacity is available prior to construction with a predevelopment 

enquiry to Anglian Water. This is due to either limited capacity of existing sewer mains and 

pumping stations, or (where funding contributions are required) as a result of existing constraints on the 

system imposed by sewer flooding problems and the limit of operation of overflows from the system to 

watercourses. 

The majority of sites in Ely and Soham will need to fund upgrades or construction of new infrastructure. 

This is as a result of existing constraints on the system imposed by sewer flooding problems and the limit 

of operation of overflows from the system to watercourses. 

Development in Burwell is likely to be able to use the existing sewer system, but development in Bottisham 

will require pre-development enquiries with Anglian Water. 

The Water Supply Strategy 

The Outline WCS concluded that East Cambridgeshire would have adequate water supply to cater for all 

low to medium levels of growth in the plan period. The growth strategy assessed in the Detailed WCS is in 

line with the low to medium scenarios assessed in the Outline study and hence sufficient raw resources 

are available to serve the proposed development. 

However there is a drive to ensure the delivery of sustainable development for Cambridgeshire as a whole 

and hence there are key drivers requiring that water demand is managed in the study area to achieve long 

term sustainability in terms of water resources. The study area is in the driest part of the UK and key


Sept 2011 

4 



sources of water (rivers and aquifers) are considered to be at their limits of abstraction before ecosystems 

reliant on them would be adversely affected. It is also predicted that climate change will further reduce 

available water resources. 

In order to reduce reliance on raw water supplies from rivers and aquifers, the Detailed WCS has set out 

ways in which demand for water as a result of development can be minimised without incurring excessive 

costs or resulting in unacceptable increases in energy use. In addition, the assessment has considered 

how far development in the District can be moved towards achieving a theoretical ‘water neutral’ position 

i.e. that there is no net increase in water demand between the current use and after development has 

taken place. A pathway for achieving neutrality as far as practicable has been set out, including advice on: 

• what measures need to be taken technologically to deliver more water efficient 

development; 

• what local policies need to be developed to set the framework for reduced water use 

through development control; 

• how measures to achieve reduced water use in existing and new development can be 

funded; and 

• where parties with a shared interest in reducing water demand need to work together to 

provide education and awareness initiatives to local communities to ensure that people and 

business in the District understand the importance of using water wisely. 

Four water neutrality scenarios have been proposed and assessed to demonstrate what is required to 

achieve different levels of neutrality in the District. Total neutrality would only be achieved with very highspecification 

fittings being retrofitted into existing properties as well as rainwater harvesting and greywater 

recycling in new properties. These features can add significantly to build costs and energy use, particularly 

greywater recycling and the scenario would require significant uptake of retrofitted devices in existing 

homes and businesses. 

The assessment concluded that measures should be taken to deliver the first step on the neutrality 

pathway by implementing the low scenario, which is generally considered to require a small scale level of 

funding and partnership working. Depending on the success of the first step, higher scenarios could then 

be aspired to. The following initial measures are therefore suggested by the WCS: 

• new housing development must go beyond the minimum requirements of Building 

Regulations; 

• carry out a programme of retrofitting and water audits of existing dwellings and non 

domestic buildings. Aim to move towards delivery of 10% of the existing housing stock with 

easy fit water savings devices; and 

• establish a programme of water efficiency promotion and consumer education, with the aim 

of behavioural change with regards to water use. 

Ecological impacts 

Although the three WRZs that supply the study area are hydrologically linked to European sites 

(particularly the Ruthamford WRZ which is connected to the Nene Washes SAC/SPA & Ramsar site and 

Ouse Washes SAC/SPA & Ramsar site) and other wildlife sites, the information provided in the WRMP 

indicates that abstractions within the WRZ’s that supply the study area are not likely to lead to a significant 

effect on European sites, following limited sustainability reductions that may be required following the 

completion of the RoC process.

Surface Water Drainage Management 


Sept 2011 

5 



Conventional surface water drainage systems for new development were designed to convey rainwater 

and surface water run-off away as quickly as possible. This helps to prevent flooding of the drained area, 

but may cause flooding of downstream areas. In addition to the increased flood risk, conventional 

drainage systems can cause pollution of the receiving watercourses as impermeable surfaces accumulate 

pollutants such as hydrocarbons, tyre fragments and debris, detergents and grit and particulates. 

Sustainable Drainage Systems (SuDS) can be used to both hold back and treat surface water run-off 

thereby reduce downstream flood risk and protect or improve water quality in the water environment. 

The vision for sustainable surface water management in the proposed new growth in East Cambridgeshire 

is based on the following key aims: 

• 100% separation of surface and foul water drainage; 

• linkage to green infrastructure giving multiple benefits to users and ecology; 

• linkage to water efficiency measures, including rainwater harvesting; and, 

• linkage to the Cambridgeshire wide Surface Water Management Plan (SWMP). 

The ultimate vision for East Cambridgeshire is to achieve 100% above ground drainage for all future 

developments, where feasible. In addition, above ground drainage should include environmental 

enhancement and should provide amenity, social and recreational value. 

Although SuDS are an important tool in managing surface water drainage in the District, at a site specific 

level, the requirements of any discharge of surface water from a site are dictated by the specifics of the 

water level management system operated by the Internal Drainage Board receiving that discharge as they 

may have a preference for surface water to be discharged from a site more quickly, rather than holding it 

back. Therefore, the assessment provides advice on how SuDS should be developed to mimic the rate 

and volume of runoff that would occur from the site prior to development taking place; however the study 

concludes that a second step should occur whereby developers or development control officers seek the 

advice of the relevant Internal Drainage Board to determine whether retention of surface water is 

preferable to a faster (but controlled) rate of runoff. 

In order to inform developers of the impact of meeting SuDS requirements of legislation and the visions of 

this study on their development footprint, initial calculations have been undertaken of the volume of storage 

required to attenuate runoff along with an assessment of likely discharge locations and SuDS types that 

would be most suitable. 

Ecological Opportunities 

There may be opportunities for treated effluent to be used at a greater distance to supplement wetland 

habitat creation initiatives such as the Great Fen Project, although this would be subject to confirmation of 

acceptable water quality standards and non-prohibitive costs of infrastructure delivery. Ely and Soham 

settlements all line on or close to green corridors in Cambridgeshire and their proposed development areas 

are in locations where they could contribute, via strategic surface water attenuation features, to the 

enhancement of those corridors. The other settlements all contain opportunities through new SuDS 

opportunities linked to the new development. 

Water Cycle Strategy Recommendations and Policy 

In order to support the further development of the East Cambridgeshire’s Local Development Documents 

with respect to water services infrastructure and the water environment, the Detailed WCS reports a site


Sept 2011 

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specific assessment of the potential constraints on each of the growth sites where the majority of 

development within the District is likely to take place. 

The following policies are also recommended to deliver the Water Cycle Strategy: 

WW1 – development phasing Burwell 

Development in Burwell will need to be restricted to a minimal annual completion rate to be agreed with 

AWS and EA until a new solution is in place post 2015. 

WW2 – development phasing Bottisham 

Development in Bottisham will need to be restricted to a minimal annual completion rate to be agreed with 

AWS and EA until a new solution is in place post 2015. 

WW3 – WwTW expansion 

Expansion of the following WwTW sites should be supported: Witchford, Littleport and Soham. 

Water Supply 

WS1 – Water Efficiency in new homes 

Ensure all housing is water efficient, new housing development must go beyond Building Regulations and 

as a minimum reach Code for Sustainable Homes Level 1/2 . 

WS2 – Water Efficiency Retrofitting 

Carry out a programme of retrofitting and water audits of existing dwellings and non-domestic buildings. 

Aim to move towards delivery of 10% of the existing housing stock with easy fit water savings devices 

WS3 – Water Efficiency Promotion 

Establish a programme of water efficiency promotion and consumer education, with the aim of behavioural 

change with regards to water use. 

SWM1 – sewer separation 

Developers should ensure foul and surface water from new development and redevelopment are kept 

separate where possible. Where sites which are currently connected to combined sewers are redeveloped, 

the opportunity to disconnect surface water and highway drainage from combined sewers must be taken. 

SWM2 – above ground drainage 

Developers should aspire to achieve 100% above ground drainage for all future developments, where 

feasible. Where this is not feasible due to for example housing densities, land take, ground conditions, 

topography, or other circumstances, the development proposals should maximise opportunities to use 

SuDS measures which require no additional land take, i.e. green roofs, permeable surfaces and water 

butts. 

SWM3 – SuDS and Green Infrastructure 

Developers should ensure linkage of SuDS to green infrastructure to provide environmental enhancement 

and amenity, social and recreational value. SuDS design should maximise opportunities to create amenity, 

enhance biodiversity, provide urban cooling and contribute to a network of green (and blue) open space. 

SWM4 – SuDS and Water Efficiency 

Developers should ensure linkage of SuDS to water efficiency measures, including rainwater harvesting.

SWM5 – Linkages to SWMP and SFRA 


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Developers should ensure SuDS design supports the findings and recommendations of the 

Cambridgeshire wide Surface Water Management Plan (SWMP) and East Cambridgeshire SFRA. 

SWM6 – Water Quality Improvements 

Developers should ensure, where possible that discharges of surface water are designed to deliver water 

quality improvements in the receiving watercourse or aquifer where possible to help meet the objectives of 

the Water Framework Directive. 

ECO1 – Phasing at Burwell WwTW 

The Council includes a policy within its Core Strategy that ensures that phasing of housing to be connected 

to Burwell WwTW is timed such that it does not result in exceedence of the volumetric capacity before the 

WwTW is able to achieve the tightened P limit on its effluent discharge and that detailed assessment has 

confirmed that it is compatible with the requirements of both the WFD and the Conservation (Habitats and 

Species) Regulations 2010. 

ECO2 – Biodiversity enhancement 

It is recommended that the Council include a policy in its Core Strategy which commits to seeking and 

securing (through planning permissions etc) enhancements to aquatic biodiversity in East Cambridgeshire 

through the use of SuDS and other means as outlined in this WCS (subject to appropriate project-level 

studies to confirm feasibility including environmental risk and discussion with relevant authorities) in line 

with the Cambridgeshire Green Infrastructure Strategy. 

In addition, the following recommendations are also made by the study: 

• key partners in the WCS maintain regular consultation with each other as development 

proposals progress; 

• further potential modelling studies are undertaken either as part of site specific planning 

applications or Anglian Water proposals to increase WwTW capacity to better inform potential 

impact of development on ecological sites; 

• the WCS should remain a living document, and be reviewed on an annual basis as 

development progresses and appropriate changes are made to the various studies and plans 

that support it; 

• consider the change to Planning Policy Statements that will occur as a result of consolidation 

of national planning policy into a single National Planning Policy Framework and how this 

may affect the overall water cycle strategy; and 

• consider how policies may need to change as the Localism Bill takes effect through 2011 

into 2012. 

A detailed flow modelling study is required to investigate the flows in the lodes around Wicken Fen and 

particularly the potential for Burwell Lode to become hydrologically connected to the Fen and Wicken Lode 

under a range of future flow scenarios as a result of both an increase in the discharge volume from Burwell 

WwTW and the recent implementation of a project to pump water from Monks Lode during the winter which 

may affect the ability of Wicken Lode to continue to prevent backflow from Burwell Lode/Reach Lode. This 

study should also confirm that in such circumstances a consent limit of 0.25 mg/l of P will still be sufficient 

to prevent any deterioration of P loading in the Fen (including Wicken Lode). 

A specific further study is also required before the volumetric consents for Witcham WwTW and Littleport 

WwTW are exceeded to confirm that achieving ‘no deterioration’ within the receiving watercourses will be


Sept 2011 

8 



adequate to avoid significant deterioration of P loadings in the Ouse Washes (i.e. not compromise the 

achievement of a 0.33 mg/l P loading as per the target set by the EA RoC or the 0.1 mg/l P loading 

normally used under JNCC Common Standards Monitoring guidance, if considered more appropriate). 

Natural England have also requested the following additional studies: 

• Detailed studies to evaluate the impacts of increased discharges on wider biodiversity; 

• Water quality effects associated with discharges from Burwell and Bottisham WwTW on 

the Cam Washes SSSI; 

• Potential cumulative impacts (flood risk) of increased discharge from Burwell WwTW on 

Wicken Fen; 

• Potential cumulative flood risk impacts of Witcham, Witchford, Little Downham and 

Littleport WwTWs on the Ouse Washes. 

The conclusions of the ecological assessments contained within this Detailed WCS will need to be reexamined 

in more detail as part of any applications to increase the discharge consents for relevant 

WwTWs or planning applications associated with WwTW extensions to confirm their validity.

Glossary of Acronyms and Abbreviations 

Abbreviation Description 

AMP Asset Management Plan 

AWS Anglian Water Services 

BAP Biodiversity Action Plan 

BGS British Geological Society 

BOD Biochemical Oxygen Demand 


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9 



BREEAM Building Research Establishment Environmental Assessment 

Method 

CAMS Catchment Abstraction Management Strategy 

CBA Cost Benefit Analysis 

CFMP Catchment Flood Management Plan 

CIL Community Infrastructure Levy 

CIRIA Construction Industry Research and Information Association 

CLG Communities and Local Government 

CRC Carbon Reduction Commitment 

CSH Code for Sustainable Homes 

CSO Combined Sewer Overflow 

CWS County Wildlife Sites 

DDC District Drainage Commissioner 

DEFRA Department for Environment, Food and Rural Affairs 

DO Dissolved Oxygen 

DPD Development Plan Document 

DG2 Register of pressure of water mains 

DWF Dry Weather Flow 

DWI Drinking Water Inspectorate 

EA Environment Agency 

ECDC East Cambridgeshire District Council 

EEP East of England Plan (the RSS for the East of England) 

EGDB Ely Group of Drainage Boards 

EIB European Investment Bank 

FDC Fenland District Council 

FEH Flood Estimation Handbook 

FFT Flow to Full Treatment 

FMfSW Flood Maps for Surface Water 

GHG Greenhouse Gas 

GI Green Infrastructure 

GQA General Quality Assessment 

GWMU Groundwater Management Unit


GWR Greywater Recycling 

HA Highways Agency 


Sept 2011 

10 



HMWB Heavily Modified Water Body (under the Water Framework 

Directive) 

IDB Internal Drainage Board 

JNCC Joint Nature Conservation Committee 

l/h/d Litres/head/day (a water consumption measurement) 

LCT Limits of Conventional Treatment 

LDDs Local Development Documents 

LDF Local Development Framework 

LFE Low Flow Enterprise (model) 

LLFA Lead Local Flood Authority 

LPA Local Planning Authority 

MCA Multi-Criteria Analysis 

MLC Middle Level Commissioners 

Ml Mega Litre (a million litres) 

NE Natural England 

NH4 Ammonium 

NRD National Receptor Database (Environment Agency) 

NWA No Water Available (in relation to CAMS) 

OFWAT The Water Services Regulation Authority (formerly the Office of 

Water Services) 

OR Occupancy Rate 

O-A Over Abstracted (in relation to CAMS) 

O-L Over Licensed (in relation to CAMS) 

P Phosphorous 

PE Population Equivalent 

PPS Planning Policy Statement 

PR Periodic Review 

PS Pumping Station 

p/d Persons per dwelling 

Q95 The river flow exceeded 95% of the time 

Ramsar Site designated under the International Convention on Wetlands 

of International Importance especially as Waterfowl Habitat 

RAG Red/Amber/Green Assessment 

RBMP River Basin Management Plan 

RSS Regional Spatial Strategy (East of England Plan) 

RoC Review of Consents 

RQO River Quality Objective 

RQP River Quality Planning


RTPI Royal Town Planning Institute 

RWH Rainwater Harvesting 

SAB SuDS Approval Body 

SAC Special Area for Conservation 

SFRA Strategic Flood Risk Assessment 

SPA Special Protection Area 

SPD Supplementary Planning Document 

SPZ Source Protection Zone 

SS Suspended Solids 

SSSI Site of Special Scientific Interest 

STW Sewage treatment Works 

SUDS Sustainable Drainage Systems 

SWMP Surface Water Management Plan 

SWMS Sustainable Water Management Study 

UKCIP02 United Kingdom Climate Impacts Programme 2002 

UKCP09 United Kingdom Climate Projections 2009 

UKTAG United Kingdom Technical Advisory Group (to the WFD) 

UKWIR United Kingdom Water Industry Research group 

UPM Urban Pollution Management 

UWWTD Urban Wastewater Treatment Directive 

WCS Water Cycle Study 

WFD Water Framework Directive 

WN Water Neutrality 

WRMP Water Resource Management Plan 

WRMU Water Resource Management Unit (in relation to CAMS) 


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WRZ Water Resource Zone (in relation to a water company’s WRMP) 

WTW Water Treatment Works 

WwTW Waste Water Treatment Works

1 Introduction 

1.1 Study Need and Drivers 


Sept 2011 

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The district of East Cambridgeshire is expected to experience a significant increase in housing 

and employment provision over the period to 2031. This growth represents a challenge to the 

district in ensuring that both the water environment and water services infrastructure (WSI) has 

the capacity to sustain this level of growth and development proposed. 

A Water Cycle Study (WCS) has therefore been undertaken to determine what impact this 

growth might have on the water environment and existing WSI. The objective of the WCS is to 

identify any constraints on housing and employment growth planned for the East 

Cambridgeshire district area up to 2031 that may be imposed by the water cycle and how these 

can be resolved i.e. by ensuring that appropriate WSI is provided to support the proposed 

development. Furthermore, it should provide a strategic approach to the management and use 

of water which ensures that the sustainability of the water environment in the district is not 

compromised. 

1.2 WCS Reporting 

The East Cambridgeshire Water Cycle Study (WCS) has thus far been reported in 3 stages. A 

joint Scoping Study was produced jointly with Fenland District Council, and reported in 2009 1 . 

Proceeding this, a Stage 1 Outline WCS was undertaken, also as a joint study with Fenland 

District Council and was completed in May 2011 2 . 

The Stage 1 report assessed the baseline conditions of various elements of the water cycle in 

East Cambridgeshire and Fenland, including the natural water environment and the capacity of 

the WSI that would be used to support growth. In addition, the Stage 1 study undertook a high 

level assessment of the likely growth town locations and the proposed levels of growth within 

the districts, and determined where growth would be achievable within the existing capacity of 

both the infrastructure and the water environment at a strategic level. 

The conclusions from the Stage 1 study identified that there were key strategic issues and 

several site specific issues that required further detailed assessment to inform the production of 

the East Cambridgeshire Local Development Framework (LDF). Information on the location of 

potential options for new development sites was available following completion of the Stage 1 

Outline Study, and hence it was agreed that the full Stage 2 Detailed WCS would be 

undertaken for East Cambridgeshire. 

At the time of completion of the Stage 1 Outline study, Fenland District Council were at a less 

advanced stage in the production of their LDF and hence had less certainty with respect to 

locations of potential growth sites. It was agreed that the Detailed study for Fenland should be 

undertaken in two Stages (2a and 2b). The requirement to undertake the Detailed Stage 2 

WCS for Fenland in two distinct stages has necessitated the requirement for the Stage 2 WCS 

for East Cambridgeshire to be reported separately. A separate Stage 2a WCS has been 

undertaken for Fenland District Council 3 . 

1 

Entec (2009), Cambridgeshire Horizons, East Cambridgeshire and Fenland District Councils: Water Cycle Study and Strategic Flood 

Risk Assessment Scoping Report 

2 

Scott Wilson (2011) – East Cambridgeshire & Fenland Water Cycle Study: Outline Study – Main Planning Report 

3 URS/Scott Wilson (2011): Fenland District Council Water Cycle Study - Detailed Study: Stage 2a Report

1.3 Stage 2 - Study Governance 


Sept 2011 

13 



This Stage 2 Detailed Study has been carried out with the guidance of the Steering Group 

established for both the scoping and Stage 1 Outline Study, comprising the following 

organisations: 

• Cambridgeshire Horizons; 

• East Cambridgeshire District Council; 

• Fenland District Council; 

• Cambridgeshire County Council; 

• Anglian Water Services Ltd; 

• Environment Agency; 

• Natural England; 

• Middle Level Commissioners and associated drainage boards; and 

• Ely group of Internal Drainage Boards. 

The Steering Group met on a regular basis throughout the completion of the study to both 

guide and feedback on the assessments undertaken in support of the study. It was also 

necessary on occasions to hold additional meetings with different Steering Group meetings to 

agree specific assessment details. 

All Steering Group members have reviewed the draft study findings and approved the Stage 2 

report for publication. 

1.4 Stage 1 Outline WCS – Key Findings 

1.4.1 Wastewater and Water Quality 

The Stage 1 study concluded that whilst several Wastewater Treatment Works (WwTW) have 

capacity to accept and treat wastewater flow from growth without any changes, the following 

did not: 

• Littleport WwTW; 

• Soham WwTW; 

• Witchford WwTW; 

• Witcham WwTW; 

• Haddenham WwTW; 

• Burwell WwTW; and 

• Bottisham WwTW. 

These WwTW will require upgrades in order to service the maximum growth levels proposed in 

the district whilst meeting the water quality targets of the watercourses receiving the discharges 

and solutions have been identified through the Stage 2 WCS. 

A high level assessment of capacity in the sewer network determined whether there is likely to 

be sufficient capacity to transmit additional wastewater flow generated by growth to the various


Sept 2011 

14 



treatment works within existing infrastructure. Several locations are likely to require upgrades 

to (or new) infrastructure including sewer mains and pumping stations, these locations include: 

• Ely; 

• Littleport; 

• Soham; 

• Burwell; and 

• Haddenham; 

Further assessment of the capacity of the wastewater network in these locations has been 

undertaken relative to the potential growth locations (housing and employment). Where 

capacity is unlikely to be sufficient, new solutions and timescales have been provided. 

1.4.2 Water Supply Strategy 

The Environment Agency’s assessment of water availability 4 suggests that the principal 

sources of raw water (rivers and aquifers) supplying East Cambridgeshire are at their limit of 

available capacity without causing adverse impact on rivers and ecosystems that rely on them; 

hence further abstraction and transfer in the future to support growth is unlikely to be available. 

The Outline study concluded that AWS have adequate demand control measures and other 

water resource options planned to cater for the demand for water created by low and medium 

growth scenarios in East Cambridgeshire, but that the highest growth scenario is unlikely to be 

fully catered for by the provision of supply as set out in AWS’s Water Resources Management 

Plan (WRMP). 

A single set of growth figures have been provided for the Stage 2 study, and these numbers 

have been assessed in the study to determine whether sufficient water resources and demand 

management have been planned, or whether alternative resource development is required at a 

local level. 

An outline assessment of the likelihood of achieving water neutrality at the end of the plan 

period (2031) was undertaken for East Cambridgeshire. Water Neutrality is theoretically 

feasible in the district only for the low and medium growth scenarios and will require significant 

intervention (and financial cost) in existing housing and employment stock to reduce existing 

demand. It is not technically possible to achieve neutrality if the highest growth scenario is 

pursued. 

A detailed water efficiency and water neutrality policy pathway has been developed in the 

Stage 2 WCS to determine how East Cambridgeshire can move as close to achieving neutrality 

as possible. 

1.4.3 Ecological Assessment 

There are three statutory designated sites which were identified in the outline WCS as being 

connected to WwTW discharges in East Cambridgeshire – Wicken Fen SAC/Ramsar 

site/SSSI/LNR, Ouse Washes SAC/SPA/Ramsar site/SSSI and Cam Washes SSSI. Of the 

fifteen non-statutory County Wildlife Sites in East Cambridgeshire which are fluvial systems 

and therefore potentially vulnerable to water quality changes due to treated effluent discharged 

upstream, one (New River/Monks Lode CWS) was identified in the outline WCS as being linked 

to a wastewater treatment works. 

4 The Catchment Abstraction Management Strategies (CAMS)


Sept 2011 

15 



The Outline Water Cycle Study also identified a potential connection between discharges of 

Burwell WwTW and the New River via Catchwater Drain which is the receiving watercourse for 

the WwTW. Haddenham WwTW was identified in the Outline WCS as potentially contributing to 

an ‘in combination’ increase in phosphorus loadings in the Great Ouse as it traverses the Ouse 

Washes. 

1.4.4 Flood Risk and Surface Water Management 

The study area has significant areas which lie within the fluvial and/or tidal flood zone, with only 

the settlements of Ely, Littleport, Little Downham, Witchford, Stretham, Haddenham and Sutton, 

located on ‘islands’ of high ground above the floodplain. Development sites to be located 

immediately outside of the current urban extent of these settlements will be significantly 

constrained by flood risk. 

Significant parts of the study area are pump drained, and are reliant on flood defences to 

minimise flood risk to the existing development both from fluvial and tidal flood risk and surface 

water drainage channels. Due to the historical drainage of the area, much of the land lies below 

the levels of the channels, creating a significant residual risk if defences were to be breached 

or overtopped. Surface water flooding from the managed drainage system is a key flood risk 

that needs to be considered as capacity of this pumped system is finite. 

The assessment of flood risk has been used to inform the potential development site 

assessment in the Stage 2 WCS to determine where specific flood defence infrastructure may 

be required. 

Surface water management is a key flood risk consideration in the study area due to the fact 

that the much of land put forward for development will be within areas where surface water 

runoff is managed via complex pumping systems. These systems are designed to ensure that 

surface water flooding does not inundate generally low lying urban areas and high grade 

agricultural land. 

The southern half of the district is generally suitable for infiltration SuDS and hence developers 

should be encouraged to provide SuDS that return as much clean runoff as possible to ground. 

However the northernmost area of the district is not suitable for infiltration and will therefore be 

reliant on surface attenuation and runoff restriction, which will require sites to make land 

provision for this mitigation. 

Potential development site areas, topography and the Outline SuDS suitability assessment 

have been used to provide surface water attenuation volumes and a SuDS type review for each 

potential development area in this Stage 2 study. Further policy advice has also been 

developed for the Stage 2 WCS to aid in delivering sustainable surface water management. 

1.4.5 Stage 2 WCS Scope 

A full Stage 2 WCS follows a Stage 1 Outline study to determine the detailed infrastructure and 

mitigation solutions required to mitigate any adverse effects or infrastructure capacity shortfalls 

determined in the Outline Study. It provides this information at a level suitable to ensure that 

there are solutions to deliver growth for the preferred development allocations, including 

detailed information on the cost of this infrastructure and the policy required to deliver it. The 

outcome is the development of a water cycle strategy for the district which informs site specific 

and other DPDs of the water environment and WSI issues that need to be considered in 

bringing growth forward at various sites, including guidance for developers in conforming with 

the requirements of the strategy.


Sept 2011 

16 



The following sets out the key objectives of the Detailed WCS for East Cambridgeshire: 

• determine the required solutions to wastewater treatment for each growth town and how this 

might impact phasing of development within (and around) each town; 

• determine whether any Habitats Directive designated ecological sites have he potential to be 

impacted by the wastewater treatment strategy via a screening process; 

• determine whether additional water resources are required to support growth; 

• determine upgrades required to water supply infrastructure relative to potential options for 

growth; 

• provide a pathway to achievement of water neutrality; 

• provide detail on location specific SuDS requirements and policy recommendations to 

achieve sustainable drainage; 

• provide infrastructure phasing timelines for each growth town to determine impact of 

infrastructure and mitigation provision on housing delivery; 

• undertake a sensitivity analysis of the impacts of climate change on infrastructure provision. 

• provide developer guidance at site level; and 

• provide detailed policy recommendations. 

1.5 Study Visions and Drivers 

For each Water cycle ‘topic’, this Stage 2 study report lists the specific visions and drivers 

relevant to that topic within the relevant report section and sets out how these specific visions 

and drivers have shaped the assessment of capacity and solutions required to facilitate 

sustainable growth. There are however, several key overarching study visions and drivers that 

are described subsequently given their importance in shaping the direction of the study as a 

whole: 

• Deliver sustainable water management - the overall vision that underpins the WCS is the 

requirement to ensure that provision of WSI and mitigation is sustainable and contributes to 

the overall delivery of sustainable growth and development as set out in the Cambridgeshire 

Quality Charter for Growth; 

• aspire to achieve water neutrality – determine what is required in order to get as close as 

possible to ensuring that water demand in East Cambridgeshire at the end of the plan period, 

is no greater than it is now; and 

• Water Framework Directive compliance – to ensure that growth, through abstraction of 

water for supply and discharge of treated wastewater, does not prevent waterbodies in East 

Cambridgeshire (and more widely) from achieving the standards required of them as set out 

in the Water Framework Directive (WFD) Anglian River Basin Management Plan 

A full list of the key legislative drivers shaping the study is detailed in the Joint Outline WCS, 

and a summary table is included in Appendix 1 for reference. 

The joint East Cambridgeshire and Fenland WCS Outline report 2 defined other relevant studies 

that have a bearing on the provision of water services infrastructure for development. This list 

includes (but is not limited to the following key documents: 

• Level 1 Strategic Flood Risk Assessment for East Cambridgeshire;

• Surface Water Management Plan for Cambridgeshire (May 2011); 

• The Cambridgeshire Biodiversity Action Plan; and 

• The Cambridgeshire Green Infrastructure strategy; and 

• The Minerals and Waste Core Strategy (adopted 19 th July 2011). 

1.5.1 Climate Change 


Sept 2011 

17 



One of the key drivers for delivering sustainable water management is the future uncertainty 

caused by the effects of climate change on water supplies, flood risk and wastewater 

management 

Nationally, climate change is predicted to have the greatest effect on the East of England. The 

Outline WCS identified that, in the future, East Cambridgeshire District is likely to experience 

hotter drier summers, warmer wetter winters and rising sea levels. This is likely to have a 

significant effect on environmental conditions and will increase the impact of human activity on 

the water environment. It is therefore essential that issues of water management and climate 

change should be viewed in a more holistic way to reflect the interdependency of services and 

resources that we receive from the natural environment, and plan for their future use 

accordingly. 

Environmental sustainability and more efficient use of natural resources should be a key 

aspiration for East Cambridgeshire District Council. In order to achieve these objectives, it is 

essential that development and water services infrastructure built today considers the future 

potential impacts of climate change and incorporates adaptive measures to improve future 

resilience. Investing in infrastructure to adapt to the likely impacts of climate change now could 

provide long-term cost savings and avoid having to deal with expected climate change impacts 

in the future, e.g. by providing more climate-resilient infrastructure and ‘space for water’ now, it 

is possible to protect societies and economies (to some extent) from its potential impacts such 

as surface water flooding 5 . 

1.5.2 Changing Planning Legislation and Policy 

At the time of undertaking this Detailed WCS, significant changes were being made to national 

planning policy and legislation governing land use change and development in the UK. The 

government have proposed the Localism Bill, the aim of which is to essentially decentralise 

power away from central government to individuals, communities and councils. 

One of the key implications of the Localism Bill might be that communities take more control 

over land use and development decision making at a local level. District councils will need to 

support communities with this process and hence with understanding the implications of this 

WCS report with respect to potential impacts and effects of development on water services 

infrastructure and the water environment going forward. 

A draft National Planning Policy Framework had also been produced for consultation; the aim 

of which is to replace and simplify the system of planning policy statements (PPS). 

5 The Stern Review on the Economics of Climate Change reported that the benefits of strong and early action outweigh the 

economic costs of not acting. “Adaptation to climate change – that is, taking steps to build resilience and minimise costs – is 

essential. It is no longer possible to prevent the climate change that will take place over the next two to three decades, but it is still 

possible to protect our societies and economies from its impacts to some extent – for example, by providing better information, 

improved planning and more climate-resilient crops and infrastructure.”

1.6 Water Use – Key Assumption 


Sept 2011 

18 



For all wastewater and water supply assessments, an assumption was made on the likely use 

per new household going forward in the plan period. It was agreed with AWS that a starting 

assumption of 150l/h/d would be used to calculate wastewater generation and water use per 

person, and that this figure would also allow for estimated use in schools, hospitals and 

commercial property. 

It is acknowledged that this figure exceeds the current Building Regulations requirement of 

125l/h/d for all new homes. However, in their asset planning AWS will continue to assume this 

higher water use for new homes as their analysis has shown that even when homes are built to 

a standard of 125 l/h/d, the average household use increases over time due to various factors. 

AWS are required under their remit to the industry regulator Ofwat, to plan for the expected 

actual use and hence it is important that conclusions made on infrastructure capacity within this 

study are consistent with AWS’ planning strategies. 

This study has however considered the effect that achieving lower average per person 

consumption would have on infrastructure capacity and the water environment to assist in 

developing policy that supports and helps lead to a lower per capita consumption.

2 Proposed Growth 

2.1 Preferred Growth Strategy 


Sept 2011 

19 



For the Stage 1 WCS, three possible growth scenarios were assessed in East 

Cambridgeshire. The initial scenario (Scenario 1) was based on the growth targets as set out in 

the 2009 Core Strategy. Two further scenarios (Scenarios 2 and 3) were developed, with the 

highest (Scenario 3) based on the District Council’s vision for additional growth in the market 

towns of Ely, Soham and Littleport. 

Due to the Government’s planned revocation of the EEP, ECDC has decided to promote the 

high levels of sustainable growth possible for the district through a review of the 2009 Core 

Strategy. Whilst the initial growth planning period was until 2025, all three scenarios were 

extended to 2031 to reflect the Core Strategy review which will consider growth up to 2031. 

It is important to note that in the absence of a replacement for the RSS, the authorities of 

Cambridgeshire issued a statement committing jointly to a continued strategy of growth in the 

county. 

2.2 Housing 

The total to be assessed in the Stage 2 WCS is 9,222 dwellings. This has been calculated from 

a total of the: 

• outstanding commitments (sites over 50 dwellings); 

• outstanding commitments (sites under 50 dwellings); 

• preferred options for allocation (>50 dwellings); 

• preferred options for allocation (10-50 dwellings); and 

• windfalls 6 (2011-2031). 

The net completions 2001-10 (5,317 dwellings) have not been included within the total 

assessed in this WCS as these properties have already been built and it is therefore assumed 

that wastewater flows from these properties will already be accounted for in the measured 

flows at the WwTWs. To add these properties to the totals to be assessed would therefore be 

‘double counting’; hence net completions have been excluded. 

For the assessment of WwTW capacity and water resource availability, all sites have been 

assessed and are included in the total figure of 9,222 above. However, for site specific 

infrastructure, such as the sewer network or on-site surface water management systems 

(SuDS), only sites over 50 dwellings will be assessed. This is considered to be an appropriate 

cut-off point for site specific infrastructure as it is considered that sites with less than 50 

dwellings proposed are unlikely to have a significant effect 7 . 

However, for the assessment of WwTW capacity and water resource availability, all growth will 

be considered, regardless of the size of the site. WwTW catchments and water resource zones 

are both on a much larger scale than the individual development sites and there is therefore the 

possibility for cumulative impacts from a number of small development sites within a single 

catchment or Water Resource Zone (WRZ). Table 2-1 below gives a summary of the housing 

figures assessed in the Stage 2 WCS. 

6 At the time of undertaking the assessments, ECDC were in the process of undertaking more consultation with villages in the district 

(Village Visions consultation) on what local residents want to see in their area. 

7 if any development is proposed upstream of known sewer flooding it has been considered irrespective of the size

Table 2-1: Summary of housing figures to be assesses for East Cambridgeshire 


Sept 2011 

20 



Outstanding Outstanding Preferred Preferred 

Net commitments commitments options for options for Windfalls 

% of 

completions (sites over 50 (sites under allocation (>50 allocation (10- (2011- 

housing 

Settlement 2001-10 dwellings) 50 dwellings) dwellings) 50 dwellings) 2031) TOTAL supply 

Ely 2098 140 75 3326 56 135 5830 38.30% 

Soham 698 193 186 1240 71 240 2628 21.80% 

Littleport 571 604 187 182 39 140 1723 11.30% 

MARKET TOWNS 3367 937 448 4748 166 515 10181 71.40% 

Bottisham 26 0 50 50 0 36 162 1.10% 

Burwell 256 0 31 100 15 76 478 3.10% 

Haddenham 98 0 17 0 14 73 202 1.30% 

Newmarket Fringe 24 0 8 0 18 28 78 0.50% 

Sutton 325 0 36 0 80 108 549 3.60% 

KEY SERVICE 

CENTRES 729 0 142 150 127 321 1469 8.70% 

Fordham 40 0 11 0 0 46 97 0.60% 

Isleham 44 0 32 0 0 60 136 0.90% 

Little Downham 119 0 6 0 0 92 217 1.40% 

Stretham 60 0 11 0 0 44 115 0.80% 

Witchford 79 0 8 0 0 37 124 0.80% 

Wilburton 53 0 6 0 0 32 91 0.60% 

LIMITED SERVICE 

CENTRES 395 0 74 0 0 311 780 5.10% 

Smaller villages 315 0 54 0 0 313 682 4.50% 

Other housing in 

the countryside 

(including rural 

exception sites) 511 0 183 0 0 733 1427 9.40% 

TOTAL 5317 937 901 4898 293 2193 14539

2.3 Employment 


Sept 2011 

21 



ECDC provided estimates of land availability for preferred employment areas in the district. 

Until the employment study has been completed by ECDC, it is not possible to provide an 

accurate assessment of the likely number of jobs the proposed employment sites will provide 

and hence, how much additional water demand will be created. 

In order to determine the likely magnitude of jobs, a basic assumption was applied to how 

many jobs a hectare of employment land may provide on average 8 The total to be assessed in 

the Stage 2 WCS is 12,706 jobs (B1, B2 and B8). This has been calculated from a total of the: 

• outstanding commitments (sites over 1ha); 

• outstanding commitments (sites under 1ha); and 

• preferred options for allocation (>1ha). 

The net completions 2001-10 have not been included within the total to be assessed, as these 

employment sites have already been developed and it is therefore assumed that wastewater 

flows from these will already be accounted for in the measured flows at the WwTWs. To add 

these sites to the totals to be assessed would therefore be ‘double counting’; hence net 

completions have been excluded. 

For the assessment of water resource availability, all sites have been assessed. However for 

the assessment of WwTW capacity, not all the proposed employment sites have been 

assessed. For example, the land proposed for ‘Smaller Villages’ have not been included in the 

assessment. While this will lead to a degree of underestimation of the post growth flow to the 

WwTW, no locations are available for these sites. It is therefore not possible to identify the 

WwTW catchment to which the new employment will drain and an assessment of the WwTW 

capacity implications of the proposed growth is not possible. Only the Preferred Options sites 

have been assessed for effects on WwTW capacity. Similarly, only the Preferred Option sites 

will be assessed for site specific infrastructure (sewer network or on-site surface water 

management systems). 

Table 2-2 below gives a summary of the employment figures to be assessed under the Stage 2 

WCS. 

2.3.1 Potential Sites Locations 

The potential broad distribution of development, as identified by ECDC, is shown in Table 2-1 

(above) and Table 2-2 (below). Of these, five settlements in the district have potential growth 

sites of over 50 dwellings or employment sites over 1 Ha. They include preferred broad growth 

areas identified in the Council’s adopted Core Strategy, and a number of potential areas 

identified in the Ely, Soham and Littleport Masterplans. The locations of these are shown in 

Figures 2-1 to 2-5 below. Housing sites are highlighted with a red boundary, and employment 

sites in yellow. 

8 An average figure of 110 jobs per hectare was used based on a conservative assumption

Table 2-2: Employment growth summary 


Sept 2011 

22 



Completions 2001- Outstanding 

Outstanding 

Preferred options >1 Total outstanding 

2010 

commitments > 1 ha commitments < 1 ha ha 

Site area Jobs Site area Jobs Site area Jobs Site area Jobs Site area Jobs 

(ha) 

(ha) 

(ha) 

(ha) 

(ha) 

Ely (Old) 2.5 280 1 80 14 1518 17 1879 

Ely (new) 17 1853 2.5 280 1 80 34 3472 37 3832 

Soham 11 1193 27 11 1219 11 1245 

Littleport 19 2161 39 28 3126 29 3165 

Bottisham 0 54 0 0 0 3 1 111 1 114 

Burwell 8 869 0 0 0 17 6 664 6 680 

Haddenham 3 350 0 0 2 192 0 0 2 192 

Newmarket Fringe 0 10 0 0 0 0 0 0 0 0 

Sutton 12 1341 0 0 0 0 0 0 0 0 

Fordham 9 1047 0 0 1 93 0 0 1 93 

Isleham 2 211 0 0 52 0 0 0.5 52 

Little Downham 3 310 0 0 0 0 0 0 0 0 

Stretham 4 420 0 0 0 0 0 0 0 0 

Witchford 4 392 0 0 0 42 0 0 0.5 42 

Wilburton 0 3 0 0 0 0 0 0 0 0 

Smaller villages 9 951 2 0 6 688 7 723 14 1411 

TOTALS 101 11,164 7 559 12 1,314 101 10,832 119 12,706

Figure 2-1: Potential development sites in Ely 

Figure 2-4: Potential development sites in Bottisham 


Sept 2011 

Figure 2-2 Potential development sites in Soham 

Figure 2-5: Potential development sites in Burwell 

l 

23 

Figure 2-3: Potential development sites in Littleport 


East Cambridgeshire – Detailed WCS

3 Detailed Wastewater Strategy 

3.1 Stage 1 Conclusions 


Sept 2011 

24 



The Stage 1 study concluded that whilst several Wastewater Treatment Works (WwTW) have 

capacity to accept and treat wastewater flow from growth without any changes, several did not 

including: 

• Littleport WwTW; 

• Soham WwTW; 

• Witchford WwTW; 

• Witcham WwTW; 

• Haddenham WwTW; 

• Burwell WwTW; and 

• Bottisham WwTW. 

The Outline Study concluded that these WwTW would require upgrades in order to service the 

maximum growth levels proposed in the district whilst meeting the WFD and habitats Directive 

water quality targets of the watercourses receiving the discharges. It concluded that solutions 

need to be identified through this Stage 2 WCS. 

A high level assessment of capacity in the sewer network determined whether there is likely to 

be sufficient capacity to transmit additional wastewater flow generated by growth to the various 

treatment works within existing infrastructure. Several locations are likely to require upgrades 

to (or require new) infrastructure such as sewer mains and pumping stations including the 

following locations: 

• Ely; 

• Littleport; 

• Soham; 

• Burwell; and 

• Haddenham; 

3.2 Wastewater Treatment Options Assessment 

3.2.1 Stage 2 assessment methodology 

As with Stage 1, the volume of wastewater generated from growth in each catchment was recalculated 

for the new growth figures and compared to the treatment capacity at each WwTW. 

If there was sufficient headroom in the existing volumetric consent of a WwTW, then the growth 

can be accepted and a solution is feasible without the need for WwTW improvements. These 

WwTWs were assigned a ‘green’ coding under the Red/Amber/Green (RAG) assessment; see 

Table 3-1and Figure 3-1 below.

Relevant 

WwTW 


Sept 2011 

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Table 3-1 WwTW with volumetric capacity to accept growth without significant WwTW 

upgrades 

Current 

BOD 

95%ile 

consent 

(mg/l) 

Current 

Ammonia 

95%ile 

consent 

(mg/l) 

Current P 

consent 

mean 

(mg/l) 

Current 

Consented 

DWF 

(m 3/ d) 

Future 2031 

DWF after 

growth 

(m 3/ d) 

RAG assessment 

2031 

volumetric 

capacity 

(m 3/ d) 

Approximate 

residual 

housing 

capacity 9 

Isleham 45A 8 - 423 267 155 492 

Newmarket 12A 4 - 6100 4,143 1957 6213 

Stretham 20A 20 - 500 228 272 863 

Wilburton 20A - - 225 204 21 67 

Ely Old 25A 15 2 10 4350 3732 618 1962 

Ely New 25A 10 2 10 1604 1297 307 975 

Mepal 40A 25 - 180 165 15 48 

For the remaining WwTWs where the flow consent would be exceeded, a new flow consent 

application is required and as with the Stage 1 study, water quality modelling was undertaken 

to determine the new quality consent conditions which would have to be applied to protect 

downstream water quality, and whether the consents are realistically achievable. The modelling 

was undertaken to show what was required to meet the two key requirements of the WFD: 

• to ensure no deterioration downstream from the current quality as a result of growth; and 

• where a receiving watercourse is currently less than the target of ‘Good Status 11 , to ensure 

attainment of future ‘good status’ is not compromised as a result of the growth. 

Modelling Tools 

Modelling of the quality consents required to meet the two WFD requirements has been 

undertaken with either one of two methods: 

• the Environment Agency’s software for calculating permit conditions - the version used is 

RQP 2.5 (River Quality Planning). The software is a monte-carlo based statistical tool that 

determines what statistical quality is required from discharges in order to meet defined 

downstream targets, or to determine the impact of a discharge on downstream water quality 

compliance statistics; 

• load standstill calculations – simplified calculations of the reduction required in the 

concentration of a discharge element to offset the increase in load that would otherwise be 

discharged as a result of increased flow volumes. The calculation determines what is 

required to ensure the overall load after increased discharge volumes is no greater than 

before growth. 

The preference has been to use RQP where sufficient data is available to support its use as it 

provides a greater degree of confidence that downstream targets and consents required to 

achieve them can be met. However, the model requires detail on the flow data in the receiving 

9 Based on an Occupancy rate of 2.1 and consumption rate of 150 l/h/d 

10 These WwTWs have a PE greater than 10,000 and discharge to ‘Sensitive Areas (Eutrophic)’ as designated under the UWWTD, it 

is therefore required that either: a) the effluent achieves 2 mg/l of P as an annual average; or b) 80% of influent P is removed by the 

treatment process. Although the WwTWs do not have a formal P consent limit, it has been assumed for calculation purposes that a 

2mg/l consent standard applies. 

11 Some watercourses are assessed through the WFD as being Heavily Modified Waterbodies (HMWB) – these watercourses only 

need to meet good ‘Potential’ (as opposed to Status) as an acknowledgement that the existing modifications to the watercourse would 

in some cases inhibit the watercourse from achieving all of the ecological and water quality targets required of it under Good Status.


Sept 2011 

26 



watercourse upstream of the discharge and several of the watercourses in the study area do 

not have suitable flow information to use in the assessment. In these cases, load standstill 

calculations have been used. Load standstill has also been used for calculation of discharge 

consents to tidal waters, due to the highly managed nature of fenland drainage systems. A 

summary of which methodology has been used for each WwTW is provided in Table 3-2 below. 

Table 3-2: Modelling Method used – summary 

Modelling Steps 

WwTW RQP used 

Load 

Standstill 

used 

Soham 

Burwell 

Bottisham 

Haddenham 

Witchford 

Littleport 

Little 

Downham 

 

Witcham 

The first stage of the modelling exercise was to establish the discharge consent standards that 

would be required to meet ‘No deterioration’; this would be the discharge consent limit that 

would need to be imposed on AWS immediately at the time that the growth causes the flow 

consent to be exceeded. No deterioration is an absolute requirement of the WFD and any 

development must not result in a decrease in quality downstream from the current status. 

The second stage was to establish the discharge consent standards that would be required to 

meet future Good Status under the WFD classification in the downstream waterbody. This 

assessment was only carried out for WwTW discharging to waterbodies where the current 

status is less than Good (i.e. currently Moderate, Poor or Bad). This would be the discharge 

consent standard that may need to be applied in the future, subject to the assessments of 

‘technical feasibility’ and ‘disproportionate cost. Such assessment would be carried out as part 

of the formal Periodic Review process overseen by OFWAT in order to confirm that the 

proposed improvement scheme is acceptable. 

Modelling assumptions and input data 

Several key assumptions have been used in the water quality and consent modelling as 

follows: 

• the wastewater generation per new household is based on an assumed Occupancy Rate 

(OR) of 2.1 people per house 12 and an average consumption ion of 150 l/h/d (as set out in 

water use assumptions – section 1.6). The 150l/h/d figure makes an allowance for 

12 For modelling purposes AWS uses 2.3p/d (persons per dwelling) for new properties but factor in a declining occupancy in existing 

properties to balance, at a regional level, forecasts of population growth and housing targets. This brings it in line with the 2.1p/d use 

din this detailed study. AWS have confirmed (Rob Morris email, Thu 30/06/2011 09:41) that they consider the approach taken in this 

study as conservative and suitable for WCS purposes. It is the same approach that has been promoted in all the WCS in the AWS 

region


Sept 2011 

27 



commercial use and use in schools and hospitals etc considered to represent increases in 

non-domestic use across the study area; 

• WwTW current flows were taken as the current consented dry weather flow (DWF). Future 

2031 flows were calculated by adding the volume of additional wastewater generated by new 

dwellings (using an OR of 2.1, a consumption value of 150l/h/d and allowance for an increase 

in infiltration) to the current consented DWF value; 

• river flow data for the RQP modelling has been provided by the Environment Agency based 

on outputs from Low Flow Enterprise (LFE) models – data was provided as mean flow and 

Q95 13 ; 

• following discussion with the Environment Agency 14 it was established that the waterbody 

classifications and targets as provided in the River Basin Management Plan, would not be 

appropriate for this detailed assessment. This is because the RBMPs report a waterbody 

classification on a large spatial scale, whereas the actual quality of a watercourse local to a 

discharge may be different and needs to be considered at a local scale. Base data for 

modelling has therefore been provided by Environment Agency water quality planners. The 

WFD 'no deterioration' targets for each WwTW are the downstream status, for each water 

quality element, based on river monitoring data collected between 2006 and 2008. Where 

significant improvement has occurred since 2008, or is planned through 

confirmed RBMP measures, the 'no deterioration' target' is the planned status. It was 

requested by the Environment Agency that the actual data provided was used in preference 

over the published status in the RBMP. Details are provided in Appendix 2 along with the full 

results and outputs from the water quality modelling. 

• WwTW effluent quality data was not available for use in this study, therefore assumptions 

were applied to the discharge quality statistics ensuring consistent ratios between mean and 

standard deviation (or co-efficient of variation 15 ) for each parameter (see RQP print outs in 

Appendix 2 for details). 

• in order to calculate Load standstill values, where a P consent is not in place for a WwTW a 

starting assumption of a mean quality of discharge at 2mg/l was used 16 ; and 

• For the purposes of this study, the limits of conventionally applied treatment processes are 

considered to be: 

• 5mg/l for BOD; 

• 1mg/l for Ammoniacal-N; and 

• 1mg/l for Phosphate. 

The water quality modelling was then undertaken for the new growth figures; but, using the 

following steps: 

Step 1 – no deterioration 

A calculation was undertaken (using either RQP or load standstill) to determine if the receiving 

watercourse can maintain no deterioration downstream from the current quality with the 

proposed growth within limits of conventional treatment technology and what consent limits 

would be required. If no deterioration could be achieved, then a proposed discharge consent 

13 

Defined as the flow value exceeded 95% of the time i.e. a representation of low flows 

14 

Steve Hopper, Senior Environment Planning Officer (Water Quality), personal communication, email "RE: East Cambs and Fenland 

WCS - WFD classes" - Thu 03/06/2010 14:11 

15 

Approximately 1 for P, 0.5 for BOD and 0.33 for ammonia 

16 

This is a worst case assumption on the basis that many of the WwTW will not treat to this high level of P removal – therefore, if the 

assessment shows the stricter standard is achievable then it can be assumed that a solution will be feasible.

17 

Key 


Sept 2011 

28 



standard was calculated which will be needed as soon as the growth causes the WwTW flow 

consent to be exceeded. This consent has been given in Table 3-3 below and is described as 

what is required immediately. The results are presented geographically in Figure 3-1. 

Table 3-3: Stage 2 modelling results for no deterioration 

WwTW 

Soham 12 

Immediate consent requirement to 

achieve no deterioration as soon as 

flow consent is exceeded 

BOD NH4 P 

>current 

consent 

Is no deterioration 

achievable? 

1 Yes 

Burwell 9 4 0.25 No (due to Phospate) 

Bottisham 5 0.5 1 

No (due to Ammoniacal 

Nitrogen) 

Haddenham 19 4 1.9 Yes 

Witchford 18 11 

No change 

required 

Yes 

Littleport 12 4 1.7 Yes 

Little 

Downham 

14 9 

No change 

required 

Yes 

Witcham 11 18 1.9 Yes 

Green Value – no 

change to current 

consent required 

Amber Value – consent 

tightening required, but within 

limits of conventionally applied 

treatment processes 

Red Value – not 

achievable within limits of 

conventionally applied 


For Soham and Burwell, where ‘no deterioration’ could not be achieved, a new solution is 

required for growth in these catchments as the absolute requirement of the WFD cannot be met 

(see section 3.2.2- results discussion for further detail). 

Step 2 – meeting future good status 

For all WwTW where the current downstream quality of the receiving watercourse is less than 

good, a calculation was undertaken to determine if the receiving watercourse could achieve 

future Good status with the proposed growth within limits of conventional treatment technology 

and what consent limits would be required to achieve this. 

The assessment of attainment of future good status assumed that other measures will be put in 

place to ensure good status upstream so the modelling assumed upstream water quality is at 

the mid point of the Good status status for each element and set the downstream target as the 

lower boundary of the Good status for each element. 

If Good could be achieved with growth with consents achievable within the limits of 

conventional treatment, then a proposed discharge consent standard which may be needed in 

the future has been given in Table 3-4 below 17 .

WwTW 

Soham 

Burwell 

Bottisham 

Haddenham 

Witchford 

Littleport 

Little 

Downham 

Witcham 


Sept 2011 

29 



If the modelling showed that the watercourse could not meet future Good status with the 

proposed growth within limits of conventional treatment technology, a further assessment step 

three was undertaken. 

Step 3 – Is growth the factor causing failure to meet future good status? 

In order to determine if it is growth that is causing the failure to attain future good status 

downstream, the modelling in step 2 was repeated but without the growth in place (i.e. using 

current flows) as a comparison. 

If the watercourse could not meet Good status without growth (assuming the treatment 

standard were improved to the limits of conventional treatment technology), then it is not the 

growth that would be preventing future Good status being achieved and the ‘no deterioration’ 

consent standard given in Table 3-3 (Step 1) above would be sufficient to allow the proposed 

growth to proceed. 

If the watercourse could meet Good status without growth, then it is the growth that would be 

preventing future Good status being achieved. Therefore consideration needs to be given to 

whether there are alternative treatment options that would prevent the future failure to attain 

Good status 

These outputs are summarised in Table 3-4 below. 

Table 3-4: Stage 2 modelling results for future Good Status 

Potential consent required to meet future 

good status 

BOD NH4 P 

N/A – 

watercourse 

already at 

High status 

N/A – 

watercourse 

already at 

High status 

N/A – 

watercourse 

already at 

High status 

1 

1 

N/A – 

watercourse 

already at 

High status 

0.32 (with growth) 

0.37 (without growth) 

Not achievable (as 

determined through 

no deterioration 

assessment 

0.14 (with growth) 

0.13 (without growth) 

N/A – not possible to assess with available data 18 

N/A – not possible to assess with available data 




Is Good status achievable? 

No (with & without growth) 

Therefore, failure to attain future good status is 

not as a result of growth. 

No 

No (with & without growth) 

Therefore, failure to attain future good status is 

not as a result of growth. 

18 Assessment of future good status requires the use of RQP which requires input flow data for the receiving watercourse upstream. 

This was not available for all WwTWs.


Sept 2011 

30 



The methodology is designed to look at the impact of proposed growth alone, and whether the 

achievement of Good Status will be compromised. It is important that AWS have an 

understanding of what consents may be necessary in the future. The RBMP and Periodic 

Review planning processes will deal with all other issues of disproportionate costs.

3.2.2 Results Discussion 

WwTW 

Soham 

This previous section has identified constraints from modelling as follows: 


Sept 2011 

32 



• Soham, Haddenham, Witchford, Littleport, Little Downham and Witcham WwTW will exceed 

their flow consent; however, water quality modelling has shown that a solution is possible 

within the limits of conventional treatment. Implementation of the solution may require new 

treatment processes and may have an impact on phasing of development; 

• Burwell and Bottisham WwTW will exceed their flow consent and water quality modelling 

has shown that to prevent a deterioration in downstream water quality, a solution beyond 

the limits of conventional treatment would be required. 

This section discusses solutions at Soham, Haddenham, Witchford, Littleport, Little Downham, 

Burwell and Bottisham WwTW. All other WwTW in the study area will not exceed their flow 

consent and do not need a solution before growth can proceed and hence are not discussed 

further in this WCS report. 

Upgrade Requirements 

For the WwTWs where a solution is theoretically available within limits of conventional 

treatment (for no deterioration), an assessment of the likely process capacity at each WwTW 

was undertaken by URS Scott Wilson to determine the impact of timing of upgrades on the 

early phasing of development sites in East Cambridgeshire. The assessment process 

included: 

• a qualitative assessment of process capacity by consideration of whether the change in 

consent condition for either BOD, ammoniacal-N or phosphorus was significant in relation to 

the existing consent condition, and if the change was small, whether the change was likely to 

be achievable with current treatment processes; 

• using satellite imagery, whether there is potential for suitable additional land available at the 

WwTW site to expand for the inclusion of new treatment process streams; and 

• where upstream flow data is available 19 , an assessment of the impact of the additional 

discharge on flood flows to determine if the impact of growth it is likely to cause an increase 

in flood risk in the receiving watercourse. 

The results of the assessment of process capacity and land availability are summarised in 

Table 3-5 below. 

Table 3-5: Results summary of treatment process capacity at WwTW requiring an 

increase in flow consent and change in quality parameters to ensure no downstream 

deterioration 

Consent 

parameter 

19 For Burwell, Bottisham and Soham WwTWs 

Current 

consent 

standards 

Consent 

limits 

required for 

no 

deterioration 

Process assessment 

- Upgrade required? 

BOD 17A 12 Yes 

NH4 8 >Current No 

Is there space 

to expand 

WwTW 

Yes, if adjacent 

land is available

WwTW 

Haddenham 

Witchford 

Littleport 

Little 

Downham 

Witcham 

Consent 

parameter 


Sept 2011 

Current 

consent 

standards 

Consent 

limits 

required for 

no 

deterioration 

consent 

P 2 20 1 

BOD 20A 19 

NH4 5 4 

P - 

No change 

required 

BOD 20A 18 

NH4 12 11 

P - 

No change 

required 

33 



It is likely that the 

change to the consent 

could be 

accommodated within 

the existing process 

capacity of the WwTW 



could be 




No 



could be 






could be 




BOD 15A 12 Yes 



NH4 5 4 

could be 




P - 1.7 Yes 

BOD 15A 14 It is likely that the 


could be 

NH4 10 9 accommodated within 



P - 

No change 

required 

No 

BOD 12A 11 It is likely that the 


could be 

NH4 6 5 accommodated within 



No 




to expand 

WwTW 


land is available 









20 Soham WwTWs has a PE greater than 10,000 and discharges to a ‘Sensitive Areas (Eutrophic)’ as designated under the UWWTD, 

it is therefore required that either: a) the effluent achieves 2 mg/l of P as an annual average; or b) 80% of influent P is removed by the 

treatment process. Although the WwTW does not have a formal P consent value, it has been assumed for calculation purposes that 

a 2mg/l consent standard applies.

WwTW 

Consent 

parameter 


Sept 2011 

Current 

consent 

standards 

P - 

Upgrade Requirements Discussion 

Consent 

limits 

required for 

no 

deterioration 

No change 

required 

34 



No 




to expand 

WwTW 

It is considered that the consent changes required at the WwTWs in Haddenham, Witcham, 

witchford and Little Downham are relatively small and hence are likely to be achievable without 

the need to add new process streams to the WwTW. There should be no (or limited) phasing 

implications for growth in these catchments. 

Process upgrades required at Soham (for BOD), and Littleport WwTW (BOD and P) are 

significant, and hence would require new process streams to be added in order to meet the 

tighter quality conditions on the new discharge consent; Littleport would also require the 

addition of P-stripping. It is considered that upgrades required to deliver these improvements 

as part of the new application for a discharge consent would not be delivered in full until AMP6 

(2015 onwards). Because both WwTWs are considered to be at their volumetric discharge 

consent before a new consent would be needed, the maximum per annum connections to each 

of the WwTWs would need to be limited in agreement with AWS. It is possible that upgrade 

works could start in the current AMP5 round (2010 to 2015) to allow a larger number of 

connections; however, on a precautionary basis, growth has been assigned a red category until 

AMP6 (1015 onwards) with growth across the rest of the plan period assigned an amber code 

for wastewater treatment to reflect that upgrades need to be completed first. 

Flood Risk Constraints 

In order to determine whether the increase in wastewater discharged from the WwTWs as a 

result of growth is likely to impact on flood risk downstream, estimates were made of the 

percentage increase in flood flows that would occur for a variety of return period events. 

The Flood Estimation Handbook (FEH) was used to derive flow estimates of the receiving 

watercourses of Buwell WwTW (Burwell Lode), Soham WwTW (Soham Lode) and Bottisham 

WwTW (Swaffham Bulbeck Lode) for a range of flood return periods (full results are provided in 

Appendix 5). 

The calculated additional flow potentially discharging to the receiving watercourses is: 

• Burwell WwTW – 87 m³/day; 

• Soham WwTW – 782 m³/day; and 

• Bottisham WwTW is - 54 m³/day. 

These discharge values were calculated as a percentage of the flood flow for different return 

periods as shown in Table 3-6 below.

Return 

Period 


Sept 2011 

35 



Table 3-6: Additional flow from WwTW as a percentage of estimated flood flows 

Burwell Lode (Burwell 

WwTW) 

m³/day % additional 

flow of flood 

flow 

Soham Lode (Soham WwTW) Swaffham Bulbeck Lode 

(Bottisham WwTW) 

m³/day % additional flow 

of flood flow 

m³/day % additional flow 

of flood flow 

Q2 (QMED) 3629 2.41 221098 0.35 2246 2.38 

Q5 5098 1.71 301882 0.26 3110 1.72 

Q10 6048 1.45 350870 0.22 3802 1.41 

Q20 7258 1.20 412042 0.19 4838 1.11 

Q50 8294 1.05 457747 0.17 5789 0.93 

Q100 9245 0.95 503971 0.16 6912 0.77 

Q200 10368 0.84 550973 0.14 8208 0.65 

Q500 11923 0.73 614563 0.13 10282 0.52 

Q1000 13219 0.66 663898 0.12 13219 0.41 

Based on these estimates the potential additional discharges to these WwTW are not 

significant (all less than 2.5% and the majority calculated to be less than 1%). It is considered 

unlikely that these additional flows would result in a significant increase in flood levels; 

however, this should be considered as part of any proposed upgrade works at the WwTWs. 

New Solution Requirements – No Deterioration 

The modelling results show that there are two wastewater catchments where deterioration from 

the current WFD waterbody status would result from the proposed growth and hence would 

require a new solution – these are: 

• Burwell (for phosphate); and 

• Bottisham (for ammonia). 

21 Allocations and windfalls 

Burwell WwTW - Solution 

Phosphorus standards within the Burwell Lode will limit the total volume of effluent that can be 

discharged at this location. RQP modelling has shown that no further increases in flow from 

Burwell WwTW will be possible without deteriorating from the Good status for P even when 

treating at the limits of conventional treatment; an absolute requirement of the WFD is that 

there must not be a deterioration from the current status. 

With the information available to complete this assessment, it has been concluded that a new 

solution is required for the outstanding 191 homes that do not have planning permission 21 and 

6.13 Ha of employment land.


Sept 2011 

36 



There is an AMP5 P-removal scheme due for completion before 2015 at Burwell WwTW; hence 

the current consent has been assumed to be 1mg/l for the purposes of future assessment. The 

assessment undertaken for this Detailed WCS has shown that, when growth is modelled a 

consent less than (or tighter) than 1mg/l would be required to maintain good status downstream 

and this is considered to require treatment beyond that which is conventionally applied. 

However, further modelling analysis has shown that even at the current flow consent 22 , the 

Burwell Lode could not maintain downstream ‘Good status’ (0.12 mg/l or better). 

There are several options that can be considered as follows: 

a) proposed development in Burwell that has yet to be granted permission be allocated 

elsewhere 23 ; 

b) a potential alternative engineering solution is a transfer of wastewater flow generated by 

new development only to Newmarket WwTW 24 . The Forest Heath WCS details that the 

Newmarket WwTW has significant volumetric capacity (when allowing for growth in the 

East Cambridgeshire Newmarket fringes also). The distance between development in 

Burwell and Newmarket WwTW is relatively small (approximately 5km) and existing sewer 

connections could be utilised with developers funding a new sewer connection between 

existing sewers along the route of the B1103 (Burwell Road). The construction and 

commissioning of the new sewer would require a five year lead in time, and hence early 

development would be constrained for five years; or 

c) consideration could be given to installing tertiary treatment technology beyond that 

conventionally applied specifically at Burwell to treat phosphorous to a higher level. The 

technology would need to ensure a mean discharge limit of 0.25 mg/l P. Such technology 

would require an increase in energy use at the WwTW and a significant financial 

investment beyond that normally approved and funded by OFWAT. The implications of this 

option would need to be discussed between EA, AWS and OFWAT as part of the next 

Asset Management Planning round (AMP6 – 2015 to 2020). It should be noted that there 

is currently no route for developers to contribute to WwTW upgrades as these are funded 

solely by the regulated Price Review process. If Ofwat determine that price rises required 

to deliver more energy intensive technologies are not justifiable, then this would not be an 

option. 

Burwell Phasing 

With regards to early phasing, this assessment has used a worst case assumption that 

because there has been a new flow consent approved for Burwell as a result of the flow 

monitoring audit, that there is no headroom within the reviewed consented flows for growth 25 . 

However, applying industry standard calculations to determine likely actual DWF at the WwTW 

suggests headroom of approximately 350 m 3 /d (approximately 2700 homes). Whilst the 

calculation of DWF is based on gross assumptions, it demonstrates that some headroom is 

likely at the WwTW and agreement between the Environment Agency and AWS as to how 

much of this headroom could be used for growth is required; this headroom cannot be 

determined by this WCS and it is a recommendation of this WCS that ECDC should work with 

both AWS and the Environment Agency to resolve this position (and to determine alternative 

22 3 

recently revised following flow audits as described in the Outline study = 1,373 m /d. 

23 

31 dwellings of the residual Burwell target of 222 across the plan period have already been granted permission and hence cannot 

be located elsewhere. 

24 

It is considered that removal of all treated flow from the Burwell Lode would have a detrimental impact on water quality through 

increases in sedimentation, loss of aquatic habitat (lower wetted perimeter and wetted depth) and less flow for dilution of nutrients 

and other pollutants. 

25 

AWS have requested that, new consents issued as a result of the audit reflect what is required for existing flows plus a 10% 

allowance for headroom.


Sept 2011 

37 



solutions if there is deemed to be no headroom) through a series of workshops . This would 

allow some early phasing of allocated and Windfall development (191 dwellings) at a controlled 

per annum completion rate, and as such an amber coding has been applied to the first 5 year 

delivery timeframe for Burwell (as reflected in section 6.5); this controlled per annum rate would 

need to reflect that there are 31 outstanding developments to be built that already have 

planning permission in the Burwell WwTW catchment Until a solution is developed for the 

allocated and windfall sites, a red category has been applied to growth between 2015 and 

2031. 

In summary: 

• The remaining residual allocated and windfall development proposed for Burwell should be 

limited to an annual completion rate agreeable with both AWS and the Environment Agency 

up to 2015; It is likely that the 31 outstanding permissions will take any available headroom 

that can be identified up to 2012 and hence growth from allocations and windfalls should not 

be granted permission without confirmation from AWS and the Environment Agency that 

capacity is available up to 2015; 

• ECDC should meet monthly with AWS and the Environment Agency to determine a suitable 

annual completion rate up to 2015 until a long term solution can be determined; 

• ECDC should facilitate workshops with AWS and Environment Agency to develop a long 

term solution to be developed in time to implement in the next Asset Management Plan 

period (2015 to 2020) to allow all remaining residual growth to take place. 

Bottisham WwTW - Solution 

Ammoniacal-N standards within the Swaffham Bulbeck Lode will limit the total volume of 

effluent that can be discharged at this location. RQP modelling has shown that no further 

increases in flow from Bottisham WwTW will be possible without deteriorating from the current 

High Status for ammoniacal-N, even when treating at the limits of conventional treatment; an 

absolute requirement of the WFD is that there must not be deterioration from the current status. 

The modelling has shown that to maintain High Status, only a total of 7m 3 of discharge at a 

treatment level of 1mg/l of Amm-N would be possible at this location, equating to 22 homes. 

This level is lower than the number of homes already being treated at the WwTW which 

suggests that if the WwTW operated at the Ammonia limit set by the new consent recently 

issued it would prevent ‘High’ status for ammoniacal-N from being maintained irrespective of 

growth. This in turn suggests that either the WwTW currently treats Ammoniacal-N to levels 

that are beyond that considered achievable by conventional treatment or that there is a greater 

availability of flow and hence dilution in the Swaffham Bullbeck Lode than is calculated using 

conventional tools used to determine flow statistics. 

There are several options that can be considered as follows: 

a) proposed development in Bottisham that has yet to be granted permission be allocated 

elsewhere 26 ; 

b) an agreement to be reached between the Environment Agency and AWS as to how much 

additional growth would be feasible at the WwTW before it would be considered that the 

growth would be having additional detrimental impact to that currently caused by existing 

flows and flow consents. It has not been possible within this Detailed WCS (using the high 

level RQP methodology agreed with the Environment Agency) to ascertain an additional 

26 50 dwellings of the residual Bottisham target of 136 across the plan period have already been granted permission and hence 

cannot be located elsewhere.


Sept 2011 

38 



impact caused by growth alone and that additional assessment needs to be agreed and 

undertaken by the Environment Agency and AWS; 

c) a potential alternative engineering solution could be a transfer of wastewater flow generated 

by new development to Cambridge WwTW 27 . The Cambridge WCS details that although 

the WwTW does not have volumetric capacity (when allowing for growth in the Cambridge 

catchment), upgrades are likely to be possible within the limits of conventional treatment, 

hence flow from an additional 86 homes should not alter this position. Developer impact 

assessments would need to be carried out on infrastructure requirements and 

commitments made regarding developer funding of any investigation and upgrades; or 

d) consideration could be given to installing tertiary treatment technology beyond that 

conventionally applied specifically at Bottisham to treat the discharge to a higher level and 

reduce Ammoniacal-N in the final effluent. The technology would need to ensure a mean 

discharge limit of 0.5 mg/l Ammoniacal Nitrogen. Such technology would require an 

increase in energy use at the WwTW and a significant financial investment beyond that 

normally approved and funded by OFWAT. The implications of this option would need to 

be discussed between EA, AWS and OFWAT as part of the next Asset Management 

Planning round (AMP6 – 2015 to 2020); ECDC and Cambridgeshire County Council (as 

waste authority) should also be involved in discussions. As is the case for Burwell, It 

should be noted that there is currently no route for developers to contribute to WwTW 

upgrades as these are funded solely by the regulated Price Review process. If Ofwat 

determine that price rises required to deliver more energy intensive technologies are not 

justifiable, then this would not be an option. . 

e) It is recommended that the best way forward is to develop a Technical Working Group 

consisting of Environment Agency, AWS, ECDC and CCC - to look at potential options and 

issues such AWS to revisit any DWF/effluent flow data; Environment Agency to investigate 

dilution/flow regime in Swaffham Bulbeck Lode; and assess alternative discharge options. 

Bottisham Phasing 

With regards to early phasing, this assessment has used a worst case starting assumption that 

because there has been a new flow consent approved for Bottisham as a result of the flow 

monitoring audit, there is no headroom within the reviewed consented flows for growth 28 . 

However, recent measured DWF at the WwTW suggests headroom of approximately 200 m 3 /d 

(approximately 650 homes). Whilst the measured DWF is based on a limited data set, it 

demonstrates that some headroom is likely to be available at the WwTW and agreement 

between the Environment Agency and AWS as to how much of this headroom could be used 

for growth is required. This would allow some early phasing of allocated and Windfall 

development (86 dwellings) at a controlled per annum completion rate, and as such an amber 

coding has been applied to the first 5 year delivery timeframe for Bottisham (as reflected in 

section 6.5); this controlled per annum rate would need to reflect that there are 50 outstanding 

developments to be built that already have planning permission in the Bottisham WwTW 

catchment. Until a solution is developed for the allocated and windfall sites, a red category has 

been applied to growth between 2015 and 2031. 

27 It is considered that removal of all treated flow from the Swaffham Bulbeck Lode would have a detrimental impact on water quality 

through increases in sedimentation, loss of aquatic habitat (lower wetted perimeter and wetted depth) and less flow for dilution of 

nutrients and other pollutants 

28 AWS have requested that, new consents issued as a result of the audit reflect what is required for existing flows plus a 10% 

allowance for headroom.

In summary: 


Sept 2011 

39 



• The remaining residual allocated and windfall development proposed for Bottisham should 

be limited to an annual completion rate agreeable with both AWS and the Environment 

Agency up to 2015; It is likely that the 50 outstanding permissions will take any available 

headroom that can be identified up to 2013 and hence growth from allocations and windfalls 

should not be granted permission without confirmation from AWS and the Environment 

Agency that capacity is available up to 2015; 

• ECDC should meet monthly with AWS and the Environment Agency to determine a suitable 

annual completion rate up to 2015 until a long term solution can be determined; 

• ECDC should facilitate workshops with AWS and Environment Agency to develop a long 

term solution to be developed in time to implement in the next Asset Management Plan 

period (2015 to 2020) to allow all remaining residual growth to take place. 

New Solution Requirements – Future Good Potential 

There are two wastewater catchments where Good status cannot be achieved following the 

growth – these are: 

• Soham (for phosphate); and 

• Bottisham (for phosphate). 

The modelling assessments have shown that for both Soham and Bottisham, the receiving 

watercourse downstream of Bottisham could not achieve Good status without the growth and it 

is therefore factors other than the proposed growth that are preventing the achievement of 

future Good status. Attainment of future good status is therefore not a barrier to growth and ‘no 

deterioration’ consents detailed in Table 3-3 above need only be considered in this WCS. 

Ely Alternative Option 

The capacity assessment for both of the Ely WwTWs indicates there is sufficient combined 

capacity to accept wastewater from growth within existing consents. However, consideration is 

being given to the location of a new WwTW to the north of Ely. A meeting was held between 

AWS, Cambridgeshire County Council and ECDC to discuss the relocation of Cresswells Lane 

WwTW on 4th October 2010. AWS is open to such a move but it is too early to make any 

commitments and scheme viability is expected to be a key issue. The benefits will need to be 

weighed against the costs when options for serving Ely North are evaluated. The policy position 

in LDF documents will also be a consideration. AWS has therefore left the option of relocation 

to Ely North open in the Minerals and Waste LDF evidence and intends to continue this position 

at Public Examination. 

Preliminary technical feasibility of this option has been considered in this Detailed study by 

assuming a theoretical position where a new WwTW is constructed in close proximity to the 

potential North Ely development sites. It is assumed that all existing wastewater flow and all 

future flow from development from Ely would be transferred to the new WwTW and both Ely 

Old and Ely New WwTW would be closed and discharges stopped. 

The modelling has shown that, from a WFD and water quality perspective only, such an option 

would be technically feasible without resulting in a downstream deterioration in current quality, 

and that good status could be achieved downstream for all parameters when growth is


Sept 2011 

40 



included. However, this assessment only gives a preliminary view of the technical feasibility. 

Further more detailed feasibility elements would need to be assessed before the option could 

be considered in more detail should all parties be supportive of such a move. These elements 

include: 

• costs (operational and capital) and economic viability; 

• maintaining levels of wastewater treatment service to Ely whilst carrying out works; 

• disruption to the town during construction and closure of the current sites; 

• additional pumping and energy (carbon) costs of new WwTWs; and 

• sterilisation of existing sites as some infrastructure elements such as pumping stations 

would need to remain on site. 

A series of potential wastewater treatment option alternatives that could be used for a new 

WwTW considered as part of this Detailed WCS, and are included in Appendix 4. Some of 

these alternatives could be considered for any new treatment facility at Ely. 

Climate Change Sensitivity – Water Quality 

Though not directly influencing water quality and water environments, climate change has the 

potential to impact and alter the water environment through increasing river temperatures, 

reducing flows and increasing diffuse run-off from heavier rainfall and storm events, all of which 

can alter the quality of the receiving water bodies. 

The Environment Agency’s ‘Potential Impacts of Climate Change on River Water Quality’ 

study 29 reported that relatively little research has been undertaken in assessing the impacts of 

climate change on water quality. However, the following high-level findings were reported from 

the literature review undertaken as part of the study: 

• water quality will be affected by changes in flow regime; 

• lower minimum flows imply less volume for dilution and hence higher concentrations 

downstream of point discharges; 

• enhanced growth of algal blooms in rivers and reservoirs could affect levels of dissolved 

oxygen and the costs of treating water for potable supply; 

• increased storm events, especially in summer, could cause more frequent incidence of 

combined sewer overflows, discharging highly polluted waters into receiving water bodies. 

The potential impacts on urban water quality will be largely driven by these changes in short 

duration rainfall intensity overwhelming drainage systems, as well as rising sea levels 

affecting combined sewerage outfalls; 

• the most immediate reaction to climate change is expected to be an increase in river and 

lake water temperatures with subsequent effects on Dissolved Oxygen levels; 

• more intense rainfall and flooding could result in increased suspended solids, sediment 

yields and associated contaminant metal fluxes; 

• nutrient loads are expected to increase; 

• in shallow lakes, oxygen levels may decline and cyanobacteria blooms may become more 

extensive; and 

29 Potential Impacts of Climate Change on River Water Quality. Science Report SC070043/SR1, Environment Agency 2008


Sept 2011 

41 



• in the UK, there has been relatively little research on toxins in streams, lakes and sediments, 

as the problems are thought to be limited. However, climate change may alter this perception. 

Climate change studies, especially in relation to water quality and ecology, are at fairly early 

stages and the outcomes are subject to considerable uncertainty. However, understanding the 

processes and mechanisms controlling water quality and ecology, and how these combine and 

interact, is essential for sustaining potable water supplies and conserving river systems. 30 As 

such, the findings of this study and planned adaptation and mitigation options should be 

updated when further research and guidance becomes available. 

One of the key climate change adaptation challenges will be managing increased wastewater 

flows (from new developments) while protecting the water environment in the area, particularly 

where the impacts of climate change on the water environment are still uncertain. The Detailed 

WCS has undertaken a sensitivity analysis on the vulnerability of water quality to climate 

change impacts through assessing the impact of reduced summer flows on dilution of 

wastewater discharges. A broad brush sensitivity was undertaken using RQP whereby the 

Q95 of the receiving watercourse has been reduced by 20% to model a reduction in summer 

flows. The consent requirements for the WwTW were then determined assuming the WFD 

objective of ‘no deterioration’ under these conditions compared to those under the existing 

climate. These results are summarised in Table 3-7. It should be noted that only WwTW that 

have data for river flows in the receiving watercourses have been assessed as the RQP 

analysis cannot be undertaken without estimates of river flow statistics. 

The assessment shows that under potential future climates, WwTW consents are likely to need 

to be tighter than existing consents, but in the majority of cases these are small changes and 

discharge consents are still within the LCT. 

Climate change, water quality and adaptation 

Table 3-8 provides a summary of the potential climate change adaptation and mitigation 

measures that could be considered in the East Cambridgeshire District with regards to water 

quality and wastewater services infrastructure. The organisations likely to be responsible for 

leading these measures have been identified alongside the suggested timescale for these 

actions to start being taken forward (Immediate, Medium (1 - 10 years) and Long (10+ years)). 

30 Potential Impacts of Climate Change on River Water Quality. Science Report SC070043/SR1, Environment Agency 2008

Table 3-7: Potential Impact of Climate Change (Reduced Summer Flows) on WwTW Consent Requirements to Meet WFD Objectives 

WwTW Determinand 

Bottisham 

Burwell 

Soham 


Sept 2011 

WwTW Consent Requirements to Meet No Deterioration 

WFD Objective 

Current Climate 

(BOD/NH4 = 95%, P= mean) 

Future Potential Climate 

Change (20% reduction in 

Q95 river flow) 

42 

% 

Change 

BOD 5.22 5.13 1.8% 

Ammoniacal-N 0.52 0.52 0.0% 

P 1.38 1.38 0.0% 

BOD 9.04 8.34 8.4% 

Ammoniacal-N 4.80 4.36 10.1% 

P 0.25 0.22 13.6% 

BOD 12.93 11.98 7.9% 

Ammoniacal-N 15.48 13.83 11.9% 

P 1.20 1.09 10.1% 



Comment 

Minimal impact. BOD consent will be close to LCT but will not 

exceed limit. 

Small impact on consents but will not breach LCT or require 

significant changes to existing consents required under current 

climate 

Small impact on consents but will not breach LCT or require 

significant changes to existing consents required under current 

climate


Sept 2011 

43 



Table 3-8: Water Quality and Wastewater Potential Climate Change Adaptation and Mitigation 

Measures 31 

Potential 

Climate 

Change 

Temperature rise 

Winter rainfall increase 

Summer rainfall decrease 

Sea level rise 

Increase in weather 

extremes (heatwaves, 

intense rainfall, storms) 

Potential Impact Adaptation and Mitigation Measures 

• Decrease in Dissolved 

Oxygen in rivers – 

impact on river ecology 

and wildlife 

• Faster wastewater asset 

deterioration 

• Changes in wastewater 

process efficiency 

• Increased diffuse 

pollution 

• Insufficient infrastructure 

capacity – storm tanks, 

CSOs etc. 

• Increased risk to rivers 

from combined sewer 

outflows 

• Degraded wetlands 

• More frequent low river 

flows 

• Less dilution in rivers for 

wastewater discharge 

• Reduced risk to rivers 

from combined sewer 

outflows 

• Tightening of discharge 

consent 

• Reduced flexibility – 

effluent required to 

maintain river flows 

• Saline Intrusion 

• Asset loss 

• Increased flooding and 

risk of service loss 

• Increased clean-up costs 

• Inability of infrastructure 

to cope 

• Increased subsidence – 

pipe failure 

• Ensure climate change mitigation 

strategies are in place for species and 

habitats at risk, e.g. BAPS 

• Monitor long-term Dissolved Oxygen 

levels in rivers and impacts 

• Improve resilience of wastewater assets 

to temperature rise, where new assets 

are required or upgraded 

• Where possible, control diffuse pollution 

runoff through SuDS 

• Promoting the creation and preservation 

of space (e.g. verges, agricultural land, 

and green urban areas, including roofs) 

in support of water quality, biodiversity 

and flood risk goals 

• Long-term monitoring of CSO spill 

volume and frequency. Ensure Urban 

Pollution Management (UPM) study is 

undertaken for major development 

upstream of CSOs 

• Ensure climate change mitigation 

strategies are in place for species and 

habitats at risk, e.g. Biodiversity Action 

plans 

• Consideration of future climate change 

impacts on wastewater discharges when 

renewing consents 

• Monitor water quality for potential 

impacts from saline intrusion 

• Ensure that key assets are located 

inland and are not susceptible to being 

lost through sea level rise 

• Promoting the creation and preservation 

of space (e.g. verges, agricultural land, 

and green urban areas, including roofs) 

in support of water quality, biodiversity 

and flood risk goals 

• Improve resilience of key wastewater 

assets such as CSOs, WwTW and 

outfalls, including new industry design 

standards for wastewater assets 

Lead Organisation (s) 

ECDC EA AWS NE 

31 Some inputs edited from AWS Strategic Direction Statement 2010 – 2035 http://www.anglianwater.co.uk/about-us/statutory- 

Timescale 

for Action 

Medium 

Medium 

Medium 

Immediate 

Immediate 

Medium 

Medium 

Medium 

Medium 

Long 

Immediate 

Medium

3.3 Ecological Appraisal 


Sept 2011 

44 



There are three statutory designated sites which were identified in the outline WCS as being 

connected to WwTW discharges in East Cambridgeshire – Wicken Fen SAC/Ramsar 

site/SSSI/LNR, Ouse Washes SAC/SPA/Ramsar site/SSSI and Cam Washes SSSI. Of the 

fifteen non-statutory County Wildlife Sites in East Cambridgeshire which are fluvial systems 

and therefore potentially vulnerable to water quality changes due to treated effluent discharged 

upstream, one (New River/Monks Lode CWS) was identified in the outline WCS as being linked 

to a wastewater treatment works. These designated sites are therefore the focus of this water 

quality appraisal. The ecological background to the statutory designated sites included the 

details of the interest features and relevant condition assessments are provided in Appendix 7. 

3.3.1 Wicken Fen SAC/Ramsar site/SSSI/Local Nature Reserve 

The SAC and Ramsar features present at Wicken Fen that are sensitive to Water Quality 

Consents (taken from the Environment Agency Habitats Directive Handbook Appendix 3) are: 

• Fens and wet habitats not acidification sensitive 

• Bogs and wet habitats, acidification sensitive 

• Non-migratory fish & invertebrates of rivers 

• Amphibians 

reports/strategic-direction/ 

ECON Consultancy was commissioned by Natural England to survey for spined loach in 2009 

in several parts of the Great Ouse catchment. This species is recognised as threatened in 

Europe and has been listed under Annex II of the EC Habitats Directive. A spined loach density 

of 0.15 individuals per m 2 was recorded for Wicken Lode and Monk’s Lode at Wicken Fen. 

Densities ranged from 0.3 to 0.27 individuals per m 2 at Wicken Lode and an abundance 

estimate of 0.22 individuals per m 2 calculated for Monk’s Lode. These results indicate a viable 

population within Wicken Fen, which had increased since the previous survey. The distribution 

of spined loach within the sampled area of Wicken Fen appeared to be linked positively with 

the cover of submerged macrophytes. 

In addition to spined loach, Wicken Lode/Wicken Fen SSSI contains a number of other fish 

species as listed in the table below.


Sept 2011 

45 



The communities of Wicken Lode have relatively few floating-leaved species and an 

abundance of submerged, slender-leaved species. At present they are best placed somewhere 

in the Potamogeton pectinatus - Myriophyllum spicatum community (Fennel-leaved Pondweed, 

Spiked Water Milfoil) There are also scarce plants including flat‐stalked pondweed 

(Potamogeton friesii) and long‐stalked Pondweed (Potamogeton praelongus), both ‘RDB near 

threatened’ species and the rare species Nitella tenusissima which has been recorded in turf 

diggings and, in 1992, in Wicken Lode. Wicken Lode also contains a diverse invertebrate 

assemblage including the rare Depressed River Mussel Pseudanodonta complanata, also an 

SSSI interest feature. 

There is a general assumption (used for example in the Environment Agency Review of 

Consents) that pollution and/or excessive nutrients, particularly phosphorus, may cause 

damage or undesirable change to the other features. Therefore, phosphorus is the main focus 

for the assessment of water quality discharges. The target of 0.1mg/litre Soluble Reactive 

Phosphorus (annual average) is used as a provisional “threshold value” for river water in and 

adjacent to the site as per the EA RoC and JNCC Common Standards Monitoring guidance. 

Wicken Lode, where the spined loach is found, is the main source of water for Wicken Fen, 

both during normal flow conditions and during floods. The only other sources of water are 

rainfall, and drainage from agricultural land to the north of the Fen into Drainer’s Dyke (this 

dyke is isolated from other dykes on the fen because of water quality concerns but there are no 

consented discharges implicated here). Therefore, for the purposes of this assessment, if the 

water in Wicken Lode meets the 0.1mg/litre SRP as an annual average, no further assessment 

of water quality discharge consents will be required. 

There is no routine water quality sample point on Wicken Lode but there is one upstream on 

New River which feeds Wicken Lode. According to the Review of Consents work, SRP has 

never been above 0.033mg/litre during the whole of this survey period, which is well below the 

0.1mg/litre Favourable Condition Table required standard. 

Burwell WwTW discharges to the Catchwater Drain which itself drains to Burwell Lode. Wicken 

Lode flows into Burwell Lode at the south-west corner of Wicken Fen. It is theoretically 

possible for water to backflow from Burwell Lode into Wicken Lode, but the EA in their RoC 

considered this a sufficiently low eventuality that they did not consider backflow of water from 

Burwell Lode into Wicken Lode further (stating that ‘there is currently no connectivity between 

… Wicken Fen and the water in Burwell and Reach Lodes’) other than to state that if any 

proposal to abstract water from the southern end of Wicken Lode to back up the fen came 

forward a detailed investigation to determine whether Burwell Lode does backup Wicken Lode 

would be required. 

This is supported by Harding et al (2005) 32 which states that ‘Wicken Lode does not appear to 

be degraded by eutrophic water backing up from Reach Lode’ [Reach Lode merges with 

Burwell Lode before it reaches Wicken Lode]. 

This being the case, there is no evidence on which to conclude that discharges to Burwell Lode 

associated with the increase in discharges from Burwell WwTW as described in this Detailed 

WCS will have any impact on Wicken Lode or Wicken Fen with regard to any of its ecological 

features, based on extrapolation of historic trends/information. 

32 

Cook A. and Harding M. (2005) An evapotranspiration groundwater water balance for Wicken Fen. Ecology, Land 

and People (elp) on behalf of the National Trust 

Harding M., Smith K. And Williamson B. (2005) The ecohydrology of Wicken Fen and a Water Level Management 

Strategy. Ecology, Land and People (elp) on behalf of the National Trust


Sept 2011 

46 



It is noted from information supplied by Natural England that a new wind pump has been 

recently installed which will abstract water from Monks Lode during the winter, hence there will 

be some additional abstraction from Monks Lode which feeds Wicken Lode and may affect the 

ability of Wicken Lode to prevent backflow from Burwell Lode/Reach Lode. However, this is a 

complex hydrodynamic scenario which would require detailed modelling that is beyond the 

scope of the current commission. Therefore such an analysis will need to be undertaken as 

part of the application for an increase to the consented discharge volumes at Burwell. 

3.3.2 Cam Washes SSSI 

Burwell Lode flows west from the village of Burwell and joins Reach Lode approximately 1km 

upstream of the River Cam which is the watercourse into which Reach Lode drains. The Cam 

Washes are offline meadows which depend upon seasonal inundation from the River Cam to 

maintain their ornithological interest. Water quality is of some importance but the ornithological 

interest is probably influenced more by inundation period/depth and vegetation management 

regime than it is by water quality 33 . 

Burwell and Bottisham WwTW’s will both require changes to their discharge consents to ensure 

‘no deterioration’ in the quality of the receiving watercourses as a result of the increased 

discharge volumes from each WwTW. In neither case can this be achieved within the limits of 

conventional treatment (although for Bottisham this relates to the necessary nitrate standard 

rather than the phosphorus standard, which can be achieved within the limits of BAT). For both 

WwTW’s therefore solutions beyond the limits of conventional treatment will be required. Given 

that water quality is not the major factor for the ecological condition of the Cam Washes SSSI 

(although it is an important factor) and, more importantly, that Burwell WwTW and Bottisham 

WwTW are likely to make a relatively small contribution to phosphorus loads in the downstream 

River Cam 34 , it is reasonable to conclude that the upgrades necessary to achieve ‘no 

deterioration’ in the receiving watercourse should adequately address the WwTW’s individual 

contribution to phosphorus loading in the River Cam. However, this will need to be verified at 

the detailed application level. 

3.3.3 New River/Monks Lode County Wildlife Site 

The same ECON Consultancy survey that was undertaken for spined loach on Wicken Lode 

also recorded a spined loach density of 0.22 individuals per m 2 for Monk’s Lode. In addition to 

spined loach, Monks Lode contains a number of other fish species including bitterling, bream, 

dace, eel, perch, roach and pike. The lodes (including Monks Lode) also contain various 

communities of submerged and floating-leaved aquatics which belong to the class Potametea 

and are part of the SSSI interest. Drainers Dyke, and the part of Wicken Lode above its 

junction with Monks' Lode, contain much Nuphar lutea (Yellow Water-lily), together with 

Sagittaria sagittifolia (Arrow-head) and Potamogeton lucens (Shining Pondweed). This is the 

species-poor subcommunity of the Nuphar lutea community [A8a] belonging to the 

Nymphaeion alliance. 

33 

View supported by BTO Research Report no. 431 Survey and Assessment of the Birds of Berry Fen and Cam 

Washes SSSIs 

34 

Smith JT. 2005. PAPER 14-05 MODELLING THE BIO-ACCUMULATION OF 32P AND 33P IN FRESHWATER 

SYSTEMS. http://www.ndawg.org/documents/Paper14-05_000.pdf 

The average P loading for the River Cam according to this paper is 0.49 mg/l i.e.147 kg P flows through the River Cam 

per day, since the flow rate in the River Cam is of the order of 300,000 cubic metres per day. This compares with the 

additional discharges from Burwell and Bottisham WwTW which will release an average additional 76 g P per day (i.e. 

approximately 0.05% of the loading in the River Cam) not all of which will reach the River Cam.

Legend 


Sept 2011 

47 



The Outline Water Cycle Study identified a potential connection between discharges of Burwell 

WwTW and the New River via Catchwater Drain which is the receiving watercourse for the 

WwTW. Further scrutiny for the Detailed WCS has identified that before the New River flows 

through Wicken Fen (at which point it is also known as Monks Lode) it bifurcates with a 

significant proportion of the flow (up to 50% according to the EA RoC for Wicken Fen) being 

directed down the Catchwater Drain, which in turn drains to Burwell Lode. As such, the 

prevailing direction of flow will in fact prevent significant backflow into the New River and there 

is thus no evidence of a connection between Burwell WwTW and Monks Lode. 

Upware Sluice 

rivers 

" dam 

plastic membrane 

isolated drain 

clay bank 

wicken fen 

Drainer's 

Dyke 

Verral's 

Fen 

" 

" 

Wicken 

Lode 

Reach Lode 

" Sedge Fen 

Wicken 

Dyke 

Wicken Fen Pumping Station discharge point 

Monk's 

Lode 

Burwell Lode 

New 

River 

3.3.4 Ouse Washes SAC/SPA/Ramsar site/SSSI 

Catchwater 

Drain 

Kilometers 

New 

River 

± 

0 0.25 0.5 1 1.5 2 

© Crown copyright. All rights reserved. 

Environment Agency, 100026380, 

2006. 

bifurcation 

Haddenham WwTW was identified in the Outline WCS as potentially contributing to an ‘in 

combination’ increase in phosphorus loadings in the Great Ouse as it traverses the Ouse 

Washes. However, the Environment Agency Review of Consents report concluded that the 

consented discharges were unlikely to lead to a significant effect and Haddenham is not 

proposed for any changes to the current consent.


Sept 2011 

48 



The following East Cambridgeshire WwTWs within the Hundred Foot River catchment were 

provisionally identified within the Stage 3 Review of Consents report as potentially contributing 

to an ‘in combination’ effect on the SAC: 

• Little Downham STW 

• Littleport Plains Lane STW 

• Witchford STW 

• Witcham STW 

• Coveney STW 

• Mepal STW 

• Wilburton STW 

Three WwTW’s – Little Downham, Witchford and Witcham – were identified as being 

responsible (at the time the Stage 3 RoC was undertaken) for more than 70% of the total 

average P load from these 7 WwTW’s. In contrast, Littleport WwTW is the smallest Anglian 

Water STW in the catchment, and currently contributes 0.7% of the total. The RoC report 

comments that ‘the effect of … Littleport Plains Lane STW … is trivial against the input from the 

main STWs’. 

Although it provisionally identified an ‘in combination’ effect as a result of these WwTW’s at 

Stage 3 the RoC process having evaluated this in greater detail for Stage 4 concluded in the 

Stage 4 Report that ‘the water quality in the Hundred Foot Drain is dominated by the water 

quality upstream of Earith in the Bedford Ouse Catchment. Phosphate concentrations do not 

increase along the course of the Hundred Foot River, suggesting that inputs from the STWs 

[listed] above are having little or no effect on water quality within this watercourse. In addition 

the connection between the Hundred Foot River and the designated SAC rivers is limited and 

meaning water quality in the Hundred Foot River is unlikely to significantly influence the Old 

Bedford’. The RoC therefore ultimately concluded that there was no amendment required to the 

existing consents for these seven WwTWs. The RoC does state the intention to achieve 

improvements to discharges upstream of Earith in order to achieve a phosphate concentration 

of 0.33mg/l in the Hundred Foot River in part on the basis that a concentration of 0.1 mg/l 

would never be achievable for this watercourse. 

The Review of Consents report only covers internationally important features of the Ouse 

Washes. The SSSI features on the Ouse Washes most likely to be affected by water quality 

issues are the ditch feature and the vascular plant assemblage feature (some of which is found 

within the ditches) and which includes nationally scarce species. 

The Hundred Foot River replenishes the internal ditch system on the Washes during the 

summer. As such, there is a direct connection between the water quality of the Hundred Foot 

River and that of the SSSI ditches within the Washes and perhaps a closer connection than 

with the SAC features. JNCC Common Standards Monitoring guidance for ditch features 

indicates a target phosphate concentration of 0.1 mg/l. 

However, while the RoC does not directly consider SSSI features, the fact that it concludes that 

water quality in the Hundred Foot River is dominated by sources upstream of Earith and that 

inputs from WwTWs that discharge along the Hundred Foot River do not appear to influence 

phosphate concentrations implies that they are also unlikely to currently play a significant role 

in influencing phosphate concentrations in those SSSI ditches that are replenished by the 

Hundred Foot River during summer.


Sept 2011 

49 



The current evidence therefore does not indicate that existing phosphate discharges from the 

WwTWs in East Cambridgeshire are likely to be having an adverse effect upon the Ouse 

Washes SAC/SPA or SSSI. 

Before changes to the consents for relevant WwTWs are made, it is necessary to determine 

which WwTWs that discharge to tributaries of the Hundred Foot River are likely to require 

changes to their consented discharge volumes and quality standards and whether this will 

result in a change to the existing situation. The level of analysis possible for the detailed Water 

Cycle Study is constrained by the limitations of the models used for this study which cannot 

predict the change in actual phosphate concentration downstream of the immediate receiving 

watercourse. As such it is not possible as part of this study to determine the actual change in 

phosphate concentration in the Hundred Foot River which will result from the specific WwTW 

improvement schemes and thus to provide any detailed analysis of the resulting ecological 

effect. These matters must therefore be modelled in fuller detail as part of the process of 

securing amendments to the discharge consents for each relevant WwTW. 

Only a relatively superficial analysis is therefore possible for the Detailed WCS. 

Mepal and Wilburton can accommodate growth within their existing consent limits and impacts 

will therefore have been addressed through the Review of Consents process and consent 

approvals procedures. Coveney is not allocated for new development. Therefore the focus of 

assessment will be upon Witchford WwTW, Witcham WwTW, Littleport WwTW and Little 

Downham WwTW. 

The modelling for the WCS was undertaken to show what was required to meet the two key 

requirements of the WFD: 

• to ensure no deterioration downstream from the current quality as a result of growth; and 

• where a receiving watercourse is currently less than the target of ‘Good Status to ensure 

attainment of future ‘good status’ is not compromised as a result of the growth. 

Although there is no direct link between this modelling and Habitats Directive water quality 

targets, the achievement of ‘no deterioration downstream’ from current quality should also 

ensure that Habitats Directive targets are not breached given that the RoC has identified that 

the current effect of Witchford, Little Downham, Littleport and Witcham WwTWs on water 

quality in the Hundred Foot River is acceptable in that it does not require amendments to the 

existing consents.. 

For Witchford and Little Downham no change in P consent is required to achieve no 

deterioration downstream. For Littleport and Witcham, it has been determined that a P limit 

would need to be introduced to achieve no deterioration downstream. These limits are 

identified as 1.7 mg/l and 1.9 mg/l respectively i.e. a 15% and 5% tightening compared to 

current discharges 35 . In both cases, this is considered to be achievable within the limits of 

conventional treatment. It is considered that the consent changes required at the WwTWs in 

Witcham and Little Downham are relatively small and hence are likely to be achievable without 

the need to add new process streams to the WwTW. There should therefore be no (or limited) 

phasing implications for growth in these catchments. Assuming solutions are put in place to 

achieve this, growth in these catchments should not present an impact on the Ouse Washes. 

Since the EA intend to introduce improvements to discharges upstream of Earith it will be 

necessary to ensure that any new water quality solutions for both Witcham and Littleport 

35 In order to calculate load standstill values, where a P consent is not in place for a WwTW a starting assumption of a 

mean quality of discharge at 2mg/l was used


Sept 2011 

50 



WwTW’s will enable phosphate loadings in the Hundred Foot River to be maintained at 0.33 

mg/l and potentially 0.1 mg/l. 

The conclusions reached in this section will need to be verified at the project-level when a 

detailed solution is devised and the associated planning applications are made. 

3.3.5 Ecology outside designated sites 

In addition to impacts on designated sites, a range of other UK or Cambridgeshire BAP species 

or otherwise protected/notable species that are found in Cambridgeshire can be affected by 

wastewater discharge. These include: 

• Water vole (protected through Wildlife & Countryside Act 1981 and a UK BAP species) 

• Grass snake (partially protected through Wildlife & Countryside Act 1981) 

• Common toad (UK BAP species) 

• Great crested newt (legally protected through Conservation of Habitats & Species 

Regulations 2010, Wildlife & Countryside Act 1981 and a UK BAP species) 

• Birds such as kingfisher (protected through Wildlife & Countryside Act 1981 and a UK BAP 

species), reed bunting, sedge warbler and reed warbler 

• Invertebrates such as the hairy dragonfly Brachytron pratense, the aquatic beetle Donacia 

dentata, the weevil Bagous subcarinatus and the diving beetle Agabus undulatus 

• Rare plant species including grass-wrack pondweed Potamogeton compressus, fringed 

water-lily Nymphoides peltata and greater water-parsnip Sium latifolium. 

• European eel (protected under the Eels (England & Wales) Regulations 2009); and 

• Otter (legally protected through Conservation of Habitats & Species Regulations 2010, 

Wildlife & Countryside Act 1981 and a UK BAP species) 

Similarly important habitats (all listed in the Middle Level BAP) include: 

• Drainage ditches; 

• Rivers; 

• Reedbeds; 

• Fens; 

• Grazing marsh; 

• Open water. 

Cambridgeshire BAP habitats present (or possibly present) in East Cambridgeshire are 

Fenland Drainage Ditches, Fens, Rivers & Streams, Floodplain Grazing Marsh and Reed beds, 

as well as the following BAP species: bittern (particularly Wicken Fen and Woodwalton Fen), 

white-clawed crayfish, Desmoulin’s whorl snail (at Wicken Fen), otter (particularly in the Cam 

catchment) and water vole. 

It is not possible within the scope of this commission to undertake a detailed investigation and 

evaluation of the impacts of the changes in water quality/flow and infrastructure to be delivered 

under the water cycle study on wildlife generally, since it would be necessary to undertake 

detailed species surveys of each watercourse and utilise detailed flow and quality 

data/modelling which has not been available for this commission for most watercourses.


Sept 2011 

51 



Eight WwTWs in East Cambridgeshire will require a change to their consents in order to 

comply with the Water Framework Directive requirements for no deterioration downstream: 

• Soham WwTW 

• Burwell WwTW 

• Bottisham WwTW 

• Haddenham WwTW 

• Witchford WwTW 

• Littleport WwTW 

• Little Downham WwTW 

• Witcham WwTW 

For all but two of these ‘no deterioration’ is achievable within the limits of Best Available 

Technology. With such consent tightening in place there should be no deterioration in 

downstream water quality and therefore there will be no adverse effects on wildlife in the 

receiving watercourses. 

Burwell and Bottisham will however require novel treatment solutions to enable ‘no 

deterioration’ to be achieved. By definition novel solutions carry an inherent risk. Burwell 

discharges to the Burwell Lode while Bottisham discharges to Swaffham Bulbeck Lode. 

Burwell Lode includes populations of the scarce chaser dragonfly (a Red Data Book species) 

which has been regularly found since 2005. It also has a substantial fish population as 

recorded in the Wicken Fen Recording and Research Newsletter for November 2010. 

Biological GQA results for the upper reaches of Burwell Lode are good or very good, i.e. a 

good representative invertebrate fauna for that particular river type. The opposite is true for the 

downstream stretch of Burwell Lode where the Biological GQA grades are fairly good, 

compared with the good chemical grades. 

There is less ecological data available for Swaffham Bulbeck Lode than for Burwell Lode but it 

also contains a fishery including eel and pike.


Sept 2011 

52 



The solutions selected for Burwell and Bottisham WwTW will need to take into account 

ecological impacts on these species and others using the receiving watercourses as part of any 

planning application associated with expansion proposals. 

3.3.6 Flood risk 

Flood risk calculations are only available for three WwTW’s covered by the Detailed WCS – 

Burwell, Soham and Bottisham due to an absence of flow and/or cross-sectional data for other 

receiving watercourses. For the three WwTW’s included, it is shown that on average flood flows 

will only increase by 0.1 -2.5% as a result of these effluent discharges. 

Burwell WwTW discharges to the Burwell Lode. There is theoretical potential for backflow from 

Burwell Lode into Wicken Lode (although the predominant direction of flow is from Wicken 

Lode into Burwell Lode). However, it is unlikely that a maximum 2.5% increase in flows (i.e. an 

additional 87 m 3 /day) will cause flooding issues for Burwell Lode. It is also unlikely that this will 

cause backflows to reach sufficiently far up Wicken Lode that it reaches one of the abstraction 

points for Wicken Fen. However, this would require more detailed investigation as part of the 

consent applications for changes to Burwell WwTW. 

Bottisham WwTW and Burwell WwTW both discharge into watercourses that drain to the River 

Cam as it flows past the Cam Washes SSSI. However, a combined additional flow of 141 

m 3 /day is unlikely to contribute materially to additional flood risk in the SSSI given that the 

mean flow in the River Cam is in the order of 300,000 m 3 /day, constituting as it will an increase 

of considerably less than 0.1%. 

Soham WwTW discharges into Soham Lode, which is not in itself designated but is likely to 

contain populations of water vole and other species that are at risk from excessive inundation 

or high flows. The additional discharges from Soham WwTW will however constitute an 

increase in flows in Soham Lode of less than 0.5% even under return period Q2 and are 

therefore unlikely to make a material contribution to flooding. 

In addition to water quality effects, discharges from WwTWs can also contribute cumulatively to 

flooding of the Ouse Washes, which could adversely affect the breeding bird interest by leaving 

nesting habitat unusable. In the Detailed Wastewater Strategy (Chapter 3 of this report) the 

contribution of increased WwTW discharges to flood risk downstream was determined for those 

WwTWs for which sufficient data were available to make an assessment. However, for those 

WwTWs in East Cambridgeshire of relevance to the Ouse Washes (particularly Witchford 

WwTW, Witcham WwTW, Little Downham WwTW and Littleport WwTW as these will all require 

increases in their volumetric consents) insufficient data are available to make a detailed 

assessment of actual changes in flows in the receiving watercourse. 

However, given the large flow volumes experienced at the Hundred Foot River (over 1 million 

m 3 per day at Earith, with mean annual flood flows of ten million m 3 /day 36 ) it is unlikely that the 

collective additional discharges from Witchford, Witcham, Little Downham and Littleport 

WwTWs (approximately 623 additional m 3 /day Dry Weather Flow by 2031) will materially alter 

these flow rates, or make a material contribution to any in combination increase and it is not 

considered that it would be likely to pose a fundamental constraint to the connection of new 

housing to these WwTWs. 

36 Environment Agency. 2004. Strategic Appraisal Report Supporting Report 4 - Fens Waterways Link: Connecting the Cathedral 

Cities

3.3.7 Ecological Enhancement 


Sept 2011 

53 



This section is intended to describe ecological enhancement opportunities to which the 

initiatives developed within the WCS could contribute. 

There are theoretically considerable opportunities available to enhance the biodiversity of East 

Cambridgeshire through initiatives associated with the WCS. As a first step towards identifying 

these opportunities the Cambridgeshire Green Infrastructure (GI) Strategy was reviewed for the 

Outline WCS in order to determine which, if any, WwTWs are physically close to any of the 

green corridors initiatives identified on Drawing 050406/31 of the Strategy. Two WwTWs were 

identified as being located within or immediately adjacent to GI initiatives: 

• Chippenham WwTW is identified as being within the Icknield Way Enhancement Corridor; 

and 

• Reach WwTW is identified as being within the Devils Dyke Extension (Restoration) Project 

area. 

These would potentially be the WwTWs that could contribute most directly to initiatives within 

the GI Strategy. However, both initiatives involve terrestrial ‘dry’ habitats such as calcareous 

grassland and there would appear to be little opportunity for the creation of wetland green 

infrastructure, such as the expansion of WwTW infrastructure could deliver (e.g. the provision 

of SuDS features, particularly the creation of ponds and reedbeds both of which are UK BAP 

priority habitats or using treated effluent to supply new water features). Moreover, neither 

WwTW will actually require any expansion or change to their existing consents according to the 

Detailed WCS. 

There may be opportunities for treated effluent to be used at a greater distance to supplement 

wetland habitat creation initiatives such as the Great Fen Project, although this would be 

subject to confirmation of acceptable water quality standards and non-prohibitive costs of 

infrastructure delivery. 

For all WwTW where the current downstream quality of the receiving watercourse is less than 

good, a calculation was undertaken to determine if the receiving watercourse could achieve 

future Good status with the proposed growth within limits of conventional treatment technology 

and what consent limits would be required to achieve this. Achievement of Good ecological 

status if achievable would also have significant ecological enhancement benefits; 'Good' 

ecological status means that human activities have had only slight impacts on the ecological 

characteristics of aquatic plants and animal communities. A change to ‘Good’ status can 

therefore be expected to involve an increase in the diversity (both in terms of number and 

pollution sensitivity of species) for invertebrates, fish, macrophytes and conventional vegetation 

which will in turn have positive impacts on associated amphibian and bird populations. 

It has not been possible to evaluate as part of this Detailed WCS whether most of the relevant 

WwTWs can contribute to achievement of ‘Good’ ecological status. For the three that could be 

modelled (Soham, Burwell and Bottisham) it has been determined that it would be not possible 

for the receiving watercourses to achieve Good ecological status even in the absence of the 

associated increase in discharge volumes due to other factors not associated with the WwTW. 

Reach WwTW, Burwell WwTW, Swaffham Prior WwTW and Bottisham WwTW all discharge 

into watercourses that flow through the Wicken Fen Vision area and two of these (Burwell and 

Bottisham) are likely to involve a considerable increase in discharge volumes. The Wicken Fen 

Vision is a long-term plan (up to 100 yrs) to create a new nature reserve covering around 53 

square kilometres between Cambridge and Wicken Fen Ramsar site. These WwTWs could 

contribute through enhanced water supply to the Vision area, aiding the conversion of farmland


Sept 2011 

54 



to fen habitat, although only where they will not also contribute to adverse water quality. This 

could render the process prohibitively expensive since it has already been established in this 

WCS that Burwell and Bottisham WwTWs will require novel treatment solutions to enable ‘no 

deterioration’ in their receiving watercourses to be achieved and since their receiving 

watercourses do not currently meet ‘good’ ecological status the discharges may require even 

greater phosphate removal before they are acceptable for use in the Wicken Fen Vision 

project. 

In addition to water quality effects, discharges from WwTWs can also contribute cumulatively to 

flooding of the Ouse Washes, which could adversely affect the breeding bird interest by leaving 

nesting habitat unusable. One major contribution WwTW expansion could therefore make is the 

provision of water supply for the creation of new areas of flooded meadow through the rerouting 

of discharges away from the Ouse Washes. This new meadow could provide breeding 

habitat for waders, as reflected in the Ouse Washes Habitat Creation Scheme being 

supervised by the Environment Agency. On the face of it Mepal WwTW, Witcham WwTW and 

Wilburton WwTW would be the most appropriate WwTWs to contribute since they all currently 

discharge to tributaries of the Ouse Washes. This would also meet the need to conserve and 

enhance the area of ‘lowland fen’ and ‘grazing marsh’ (both UK BAP habitats) within the study 

area and improve habitat for Cambridgeshire BAP species such as otter, water vole and great 

crested newt. 

3.4 Wastewater Networks 

The wastewater strategy to cater for growth also requires an assessment of the capacity of the 

wastewater network (sewer system) to accept and transmit foul flows from the new 

development to the WwTW for treatment. 

An assumption has been applied that it is preferential from a cost and phasing perspective to 

use capacity within the existing sewer network first before new sewers are built and 

commissioned. 

The capacity of the existing sewer network is an important consideration for growth, as in some 

cases the existing system is already at, or over its design capacity. Further additions of foul 

water from growth can result in sewer flooding in the system (affecting property or 

infrastructure) or can increase the frequency with which overflows to river systems occur, 

resulting in ecological impact and deterioration in water quality. 

A high level assessment of capacity in the sewer network was undertaken in the Outline study 

and determined whether there is likely to be sufficient capacity to transmit additional 

wastewater flow generated by growth to the various treatment works within existing 

infrastructure. The study concluded that several locations are likely to require upgrades to 

existing infrastructure or new infrastructure such as sewer mains and pumping stations, these 

locations include: 

• Ely, Littleport, Soham, Burwell, and Haddenham. 

The assessment undertaken for the Outline study was high level as preferred development 

sites were not identified for specific connection and capacity assessment. It was also not 

possible to undertake detailed calculations of capacity owing to the nature of the sewer network 

catchments in the study area which lack gradients due to the topography and hence rely on 

pumping stations to move the flow around and which have variable capacity. Several of the 

catchments also have areas of combined sewerage (rain water and foul water) whose capacity 

is determined by rainfall events and the acceptable frequency of spills from in built overflows in 

the system (CSOs). To accurately determine capacity in these systems, a hydraulic model of


Sept 2011 

55 



the system needs to be run to factor in rainfall variation as well as increased foul water from 

development. 

Discussions with AWS for the detailed stage have identified that whilst hydraulic models of the 

sewer system do exists for some settlements, in many cases they are old and confidence in 

their outputs is low. A summary of the model status is given below: 

• Littleport: Model could be used for assessments, but may require some local 

enhancements; 

• Soham: Part model but unverified, therefore low confidence in any results; 

• Ely: Not fit for purpose, requires updating, update scoped and currently awaiting 

prioritisation; 

• Burwell and Bottisham: no models available. 

AWS have therefore agreed to undertake an internal assessment of the capacity of the network 

system using local operational knowledge and feedback this information to ECDC as part of 

detailed updates on phasing. 

To assist initial phasing however, each proposed site has been assessed for likely impact on 

sewer network capacity in this study by determining the most likely connection route to the 

WwTW and assessing the following: 

a) if the route is subject to an existing sewer flooding problem that is not planned for 

remediation in AMP5 (2010 to 2015), then it is considered that connection is not possible 

and either an upgrade or a new sewer connection is required that would limit early phasing 

until AMP6 (2015 onwards); 

b) if the route has a CSO and development is likely to result in a 10% increase in wastewater 

flow upstream, then as a worst case assessment, it is considered that connection is not 

possible and either an upgrade or a new sewer connection is required that would limit early 

phasing until AMP6 (2015 onwards); 

c) if the route is upstream of a pumping station a recommendation is made that growth in this 

location should not proceed until AWS have deemed there is capacity at the pumping 

station through a pre-development enquiry; and 

d) the size of the sewers on the route is considered relative to the size of the development 

site, and if the size is considered to be low in relation to the growth, then a 

recommendation is made that growth in this location should not proceed until AWS have 

deemed there is capacity through a pre-development enquiry. 

A summary of the results is given in the following section, including a map showing assumed 

connection routes for each site to the WwTW. A RAG assessment has been undertaken; a key 

indicating the coding applied to each assessment is provided in Table 3-9. 

Table 3-9: Key for wastewater network RAG assessment 

development is likely to 

be possible without 

upgrades 

Pumping station or pipe size 

may restrict growth; a predevelopment 

enquiry is 

recommended before planning 

permission is granted 

DG5 incident downstream 

or site 100 properties 

upstream of a CSO – new 

solution likely.

3.4.1 Stage 2 network assessment results 

Figure 3-2: Ely Potential Wastewater Network Connections 37 

37 The Pumping Station Locations have been digitised manually and so may vary to those locations shown here 


Sept 2011 

56 

Ely Sites assessment 

Site Description of potential wastewater connection 

Lisle Lane, 

Ely (2 of 2) 

(Figure 3-2) 

Earliest 

date to 

connect 

Lisle Lane, Ely (1 of 2) (Figure 3-2) 38 

A 150mm foul water sewer runs to Cresswells Lane and then 

to the WwTW. 

There are no DG5 incidents recorded on this route. 

A 225mm foul water sewer runs to Prick Willow Road. The 

225m sewer on Prick Willow Road is gravity led and there 

very slight gradient to the west under Nutholt Lane. At the 

Paradise 

junction with Lynn Road it connects to a 700mm diameter 

Centre, Ely 

sewer and runs south. At the junction with the High Street it 

(Figure 3-2) 

connects into a 225mm diameter sewer. It the flows down Lisle 

Lane and to the Creswell Lane WwTW. There are three DG5 

recorded incidents along the High Street. 

Land west 

of 93-135 

Lynn Road, 

Ely (Figure 

3-2) 

Phase 3, 

land off 

Prickwillow 

Road, Ely 

(Figure 3-2) 

North Ely (1 

of 2) 

(Figure 3-2) 

North Ely (2 

of 2) 

(Figure 3-2) 

A 300mm foul water sewer runs under Lynn Road. This sewer 

gradual increases in diameter up to 700mm at the junction with 

the High Street where is connects into a 225mm diameter 

sewer. It the flows under Lisle Lane and to the Creswell Lane 

WwTW. 

There are three DG5 recorded incidents along the High Street. 

A 150mm foul water sewer is connected to the site and runs 

along Prick Willow Road. It is diverted off Prick Willow Road 

through the housing estate and then runs under Lisle Lane to 

the Creswell Lane WwTW. An alternative pumped sewer runs 

under Prick Willow Road; the diameter of this is unknown. 

There are no DG5 incidents recorded along this route. 

However there is a CSO located to the South East of the site 

A 160mm foul water sewer is pumped under the A10 to the 

west of this development site. After the roundabout with the 

A142 the diameter is increased to 450mm and the sewer is 

gravity drained to the WwTW in to the south of Ely. 


However, two CSOs are located just off the route south of the 

roundabout. 

There are no existing foul water sewers on the site, there are 

two in the vicinity. One is a pumped sewer (unknown 

diameter) at Thistle Corner that flows under Prickwillow Road 

and then Lisle Lane to the Creswell Lane WwTW. There is a 

CSO on this route. A 150mm diameter foul sewer runs under 

Mortons Close and is connected to a pumped sewer on Lynn 

Road. This sewer gradual increases in diameter up to 700mm 

at the junction with the High Street where is connects into a 

225mm diameter sewer. It the flows under Lisle Lane and to 

the Creswell Lane WwTW. 

There are three DG5 recorded incidents along the High Street. 

Pre-dev 

enquiry 

required? 

2011 

2015 

2015 

2011 

2011 

2015 39 



Notes 

The growth proposed at the site 

(185) is unlikely to cause significant 

capacity concerns 

The majority of the network on the 

connection route is likely to have 

sufficient capacity; however there 

are sewer flooding incidents 

downstream and hence connection 

could exacerbate this problem. A 

new solution is therefore likely to be 

required 





downstream and hence connection 

could exacerbate this problem. A 

new solution is therefore likely to be 

required 

The growth proposed at the site 

(140) is unlikely to cause significant 

capacity concerns 



sufficient capacity; however 

significant growth is proposed and 

the capacity will need to be 

confirmed by AWS operational staff 





downstream, wastewater pipe sizes 

become restricted and hence 

connection could exacerbate this 

problem. A new solution is 

therefore likely to be required 

38 This site has not been assessed as it is subject to relocation of Creswells lane WwTW upon which it would be located 

39 The area of Ely site 2 is currently in the Ely Old WwTW catchment. It is possible that connection to Ely New WwTW would be possible 

in tandem with North Ely site 1, which would be subject to a pre-dev enquiry

Figure 3-3: Littleport Potential Wastewater Network Connections 


Sept 2011 

57 

Littleport Sites Assessment 


There are three existing foul water sewers within the immediate vicinity of 

the site, which are 

- a gravity drained pipe with a diameter of 300mm that flows under the far 

eastern boundary towards Parson’s Lane; 

- a gravity drained sewer (unknown diameter) flows under the inset 

eastern boundary towards Parson’s Lane; and, 

Land at 

- a gravity drained sewer flowing from the northern boundary of the site 

Parsons 

under Parson’s Lane (unknown diameter). 

Lane, 

The first two sewers join together under the junction of Parson’s Lane 

Littleport 

and Atkins Close. From Atkins Close it flows north (unknown diameter) 

(Figure 3-3) 

under the cemetery to Wisbech Road where it joins a gravitydarined 

sewer with a diameter of 225mm. It then flows under Elm Side (unknown 

diameter) from which it is pumped via one of three sewers to the WwTW 

(150mm, 150mm and 300mm diameter sewers). 

Residue at 

Highfield 

Farm, Ely 

Road, 

Littleport 

(Figure 3-3) 

Site at 

Highfield 

Farm, Ely 

Road, 

Littleport 

(Figure 3-3) 


A 150mm gravity drained foul water sewer flows under the development 

site and flows north towards Parson’s Lane. From Parson’s Lane it 

connects to another sewer at Atkins Close. From Atkins Close it flows 

north (unknown diameter) under the cemetery to Wisbech Road where it 

joins a gravity drained sewer with a diameter of 225mm. It then flows 

under Elm Side (unknown diameter) from which it is pumped via one of 

three sewers under fields to the WwTW (150mm, 150mm and 300mm 

diameter sewers). 


A 150mm gravity drained foul water sewer flows under the development 

site and flows north towards Parson’s Lane. From Parson’s Lane it 

connects to another sewer at Atkins Close. From Atkins Close it flows 

north (unknown diameter) under the cemetery to Wisbech Road where it 

joins a gravity darined sewer with a diameter of 225mm. It then flows 

under Elm Side (unknown diameter) from which it is pumped via one of 

three sewers under fields to the WwTW (150mm, 150mm and 300mm 

diameter sewers). 


Earliest 

date to 

connect 



Pre-dev 

enquiry 

required? 

2011 

2011 

2011 

Notes 

The majority of the 

network on the 

connection route is likely 

to have sufficient 

capacity; however 

development is 

upstream of a pumping 

station which may have 

limited capacity and 

may need to be 

upgraded 











upgraded 











upgraded


Land at 

Highfield 

Farm, Ely 

Road, 

Littleport 

(Figure 3-3) 

Land north 

of Grange 

Lane, 

Littleport 

(Figure 3-3) 

A number of gravity drained 150mm foul water sewers are connected to 

the existing development in the eastern area of this site. These are all 

connected to a gravity ldrained 150mm foul water sewer that flows north 

towards Parson’s Lane. There are no DG5 incidents recorded along this 

route. 

A 225mm gravity drained foul water sewer flows under the High Street 

located adjacent to the eastern site boundary. It is joined by another 

sewer from Hempfield Road where its diameter increases to 300mm. Its 

diameter increases to 375mm as it is joined by another sewer Main 

Street. A potential flow route would then go under Church Road, Church 

Lane and the Camel Road to the pumping station. From Camel Road it 

is then pumped via a 300mm pipe under Blackbank Drove to the WwTW. 

There are two CSOs along this route 

There is one DG5 incident along this route at the junction of Eastfields 

and the High Street. 

A foul water sewer is connected to the houses on Millfield to the north of 

the development site. This connects into the 225mm gravity drained foul 

water sewer under the High Street. 

Near to the development there are two 225mm gravity led foul water 

sewer under the High Street which could be connected to. 

A 150mm gravity led foul water sewer runs under Grange Lane to the 

south of the development site, which connects into the sewers under the 

High Street. 

There is one DG5 incident along this route at the junction of Eastfields 

and the High Street. There are two CSOs along the route north of the 

High Street 


Sept 2011 

Earliest 

date to 

connect 

Pre-dev 

enquiry 

required? 

2015 

2015 

Notes 

The connection route is 

likely to have capacity 

downstream; however, 

upgrades would likely 

be required close to the 

site and sewer flooding 

may be exacerbated 

downstream. Capacity 

of pumping station is 

unknown. Solution is 

likely to be required 





capacity; however there 

is a sewer flooding 

incident downstream 

and hence connection 

could exacerbate this 

problem. A new 

solution is therefore 


58 

Figure 3-4: Soham Potential Wastewater Connections 



Soham Sites Assessment 


Station 

Road, 

Soham 

(Figure 3- 

4) 

Lion Mills, 

Mill 

Corner, 

Soham 

(Figure 3- 

4) 

Land 

northwest 

of Regal 

Drive, 

Soham 

(Figure 3- 

4) 

Keith 

Leonard 

House, 

Soham 

(Figure 3- 

4) 

A pumped foul water sewers flows under Mere Side 

adjacent to the eastern boundary of the site (unknown 

diameter. This is pumped north under Broad Piece and 

to the WwTW. 


There are two 150mm gravity drained foul water sewers 

connected to the site that combine to leave the site 

towards the north west and flow under Mill Corner. At 

the pumping station it can be pumped under Mere Side 

and then Broad Piece to the WwTW. 


however there is a CSO located just North west of the 

site near Mill corner. 

A pumped foul water sewer (unknown diameter) flows 

under Brook Street, which could be connected to from 

the south of the site. This then flows, by gravity under 

Tankers Lane and Sand Street to the pumping station 

near Mill Corner. From here it is pumped under Mere 

Side and then Broad Piece to the WwTW. 


However a CSO is located on the route near Mill corner 

A gravity drained foul water sewer flows under College 

Road to the east of the development site (unknown 

diameter). This is assumed to flow south to connect to 

another gravity sewer and flow west. This connects to 

the sewer under Mill Corner near the pumping station 

where it can be pumped under Mere Side and then 

Broad Piece to the WwTW. 


However there is a CSO near Mill Corner. 

Alternatively, this development could connect to the 

Lions Mill development, if they are progressed at similar 

times. 


Sept 2011 

Earliest 

date to 

connect 

Pre-dev 

enquiry 

required? 

2011 

2011 

2011 

2011 

Notes 



sufficient capacity; however the 

capacity of the PS will need to be 










capacity of the PSs will need to be 

confirmed by AWS operational 

staff. 






59 


Brook 

Street, 

Soham 

(Figure 3- 

4) 

A foul water sewer (unknown diameter) currently 

pumped under Paddock Street adjacent to the north 

west of the development. It then flows by gravity down 

the High Street, Clay Street and College Road. At the 

end of College Road it connects to another gravity 

sewer and flows west. This connects to the sewer 

under Mill Corner near the pumping station where it can 

be pumped under Mere Side and then Broad Piece to 

the WwTW. 


Another gravity led foul water sewer flows under Brook 

Street, which could be connected to from the south of 

the site. Although the topography of the site falls 

towards the northwest and so may not be favourable 

and could require an additional pumping station local to 

the site. This then flows under Tankers Lane and Sand 

Street to the pumping station near Mill Corner. From 

here it can be pumped under Mere Side and then 



There are foul sewers connected to The Causeway 

housing estate to the south of this development. 

Although, as with the above connection the topography 

of the site falls towards the northwest and so may not 

be favourable and could require an additional pumping 

station local to the site. As with the above two sewers 

these flow towards the pumping station near Mill Corner 

and from there are pumped under Mere Side and then 



A CSO is located near Mill Corner where all of the 

above routes connect to. 

Earliest 

date to 

connect 

Pre-dev 

enquiry 

required? 

2015 



Notes 





the capacity of the PSs will need to 

be confirmed by AWS operational 

staff. Local PS are also likely to be 

required and as such, new 

infrastructure may be needed and 

the site is assessed as Red on a 

precautionary basis


Eastern 

Gateway, 

Soham 

(Figure 3- 

4) 

Land rear 

of 

Fordham 

Road, 

Soham 

(Figure 3- 

4) 

A gravity drained foul water sewer (unknown diameter) 

is located under the north of the site which flows 

towards a pumping station. It is then pumped under 

Qua Fen Common and Holmes Lane in a 300mm 

sewer. It connects to another 300mm pumped sewer 

under Townsend and through a housing estate all the 

way to the WwTW. 


A 150mm gravity ldrained foul water sewer flows under 

Brewhouse Lane to the south of the development to 

Paddock Street. It then flows by gravity down the High 

Street, Clay Street and College Road. At the end of 

College Road it connects to another gravity sewer and 

flows west. This connects to the sewer under Mill 

Corner near the pumping station where it can be 

pumped under Mere Side and then Broad Piece to the 

WwTW. 


Other foul water sewers are connected to the houses in 

the west of the development e.g. around Queensway 

but routes to the WwTW could not be identified on the 

GIS layers provided. 

A gravity drained foul water sewer (unknown diameter) 

flows under Brook Street, which could be connected to 

from the south of the site. This then flows under 

Tankers Lane and Sand Street to the pumping station 

near Mill Corner. From here it can be pumped under 

Mere Side and then Broad Piece to the WwTW. 


Another gravity drained foul water sewer (unknown 

diameter) flows under Staples Lane to connect to the 

sewer under Brook Street. 


Another gravity ldrained foul water sewer flows under 

Fordham Road to Sand Street and then to the pumping 

station near Mill Corner. From here it can be pumped 

under Mere Side and then Broad Piece to the WwTW. 


A CSO is located near Mill Corner where all of the 

above routes connect to. 


Sept 2011 

Earliest 

date to 

connect 

Pre-dev 

enquiry 

required? 

2015 

2011 

Notes 





the capacity of the PSs will need to 

be confirmed by AWS operational 

staff. New infrastructure may be 

needed and the site is assessed as 

Red on a precautionary basis 




capacity of the PSs will need to be 

confirmed by AWS operational 

staff. 

60 

Figure 3-5: Burwell Potential Wastewater connection 



Burwell Site Assessment 


Land north A gravity drained foul water sewer (unknown diameter) 

of flows from the south west corner of the site under 

Newmarket Newmarket Road. This flows north under the 

Road, Causeway and then North Street to the WwTW. 

Burwell 

(Figure 3- There are no DG5 incidents recorded along this route. 

5) 

There are two 150mm gravity drained foul water 

sewers that are connected to the housing estate to the 

northwest of this development; one under Burghley 

Rise and one under Felsham Chase. These both 

connect to the sewer that flows under The Causeway 

leading into North Street and to the WwTW. 


Another gravity drained foul water sewer (unknown 

diameter) flows south east under Newmarket Road 

adjacent to the southern tip of the development. This 

then flows down Saacson Road and turns north at the 

junction with the High Street. It flows north under 

Spring Close to join another gravity led sewer under 

Parsonage Lane. This flows north under Low Road to 

a pumping station off Rythe Lane. It is then pumped 

through a 5inch sewer from under Rythe Lane to a 

gravity drained sewer under North Street and then to 

the WwTW. 



Sept 2011 

Earliest 

date to 

connect 

Pre-dev 

enquiry 

required? 

2011 

Notes 



sufficient capacity and there are no 

pumping stations likely to be limited 

by capacity. 

61 

Figure 3-6: Bottisham Potential wastewater network connection 



Bottisham Site Assessment 


Land east 

of Bell 

Road, 

Bottisham 

(Figure 3- 

6) 

There are no existing foul water sewers on the site, 

there are two in the vicinity. A 6inch diameter gravity 

led and a 4inch diameter pumped sewer are located 

under Bell Road approximately 100m to the west of the 

development site. These connect to a 6inch diameter 

gravity sewer under the High Street this increases to a 

9inch diameter sewer that flows under Tunbridge Lane. 

This is then pumped via a 150mm sewer under the 

houses on Paddock Drive to the WwTW. 


Another gravity ldrained foul water sewer (unknown 

diameter) is located under Stocks Close to the north of 

the development site. This also connects to the 6inch 

diameter gravity sewer under the High Street which 

increases to a 9inch diameter sewer that flows under 

Tunbridge Lane. This is then pumped via a 150mm 

sewer under the houses on Paddock Drive to the 

WwTW. 



Sept 2011 

Earliest 

date to 

connect 

Pre-dev 

enquiry 

required? 

2011 

Notes 



sufficient capacity and there are no 

pumping stations likely to be limited 

by capacity; however, extensive 

new sewers are likely to be 

required to connect the site to the 

existing system 

62 



4 Water Supply Strategy 

4.1 Introduction 


Sept 2011 

63 



The Outline study concluded that AWS has adequate demand control measures and planned 

water resource options to meet the demand for water created by the low and medium growth 

scenarios in East Cambridgeshire; however, the ,AWS Water Resources Management Plan 

(WRMP) indicates the, but that the highest growth scenario is unlikely to be fully catered for. 

A single set of growth figures have been provided for the Stage 2 study, and these numbers 

have been re-assessed. The number of outstanding dwellings and employment land targets 

are lower than the higher growth figures assessed in the Outline Study. 

In reviewing the latest update to the AWS WRMP, and through liaison with AWS it has been 

established that the growth figures assessed for the detailed study are catered for in the 2035 

prediction of supply and demand deficits in the Ely, Newmarket and Cheveley Planning Zones 

under average conditions; but that towards the end of plan period there is a small deficit in 

peak demand conditions in the Ely planning zone (see Appendix 3) for geographical coverage 

of this zone). 

4.2 The Vision 

Through a series of demand management measures and improvement of existing resources, 

AWS are predicting a supply surplus of available water in 2035 within the water resources 

zones located within East Cambridgeshire which would provide sufficient water supply to 

supply the levels of growth within the district through the plan period. 

However, there are several key drivers for ensuring that water use in the development plan 

period is minimised as far as possible. In keeping with the overall vision of the East 

Cambridgeshire WCS, there is drive to ensure new development meets the sustainable 

development aspirations within Cambridgeshire County and hence sustainable water delivery is 

a key part of achieving this vision. 

As is the case for all sustainable use of resources, the three ‘R’s of reduce, reuse and recycle 

are key to maximising the sustainability and reduce is the first and arguably most important 

element of sustainable water use to consider. 

Water neutrality (see below) is also a key aspiration of the WCS. It is therefore essential that 

water use is minimised as far as is practical. 

4.2.1 Drivers and Justification for Water Efficiency 

As well as the key study visions mentioned, there are also several other drivers and justification 

for considering more water efficient and more sustainable development. 

The study area, and East Anglia generally, is an area of serious water stress 40 and is the driest 

part of the UK. Any growth and increase in population will further exacerbate this issue. In 

addition, the key sources of raw water (rivers and aquifers) supplying East Cambridgeshire are 

considered to be at their limit of water they can continue to yield for abstraction before 

ecosystems reliant on these sources and other users of these sources would be adversely 

affected. Further abstraction, other than that currently licensed and being planned by AWS to 

2035 is not likely to be possible, and strategic transfers of water into the area would be 

40 As classified by the Environment Agency


Sept 2011 

64 



required. Based on the ‘business as usual scenario’ of 150l/h/d of water use, demand for water 

in East Cambridgeshire could increase through the plan period by 3.13 Ml/d (see Table 4-1). 

Table 4-1: Range of water demands across the plan period in East Cambridgeshire 

depending on efficiency levels of new homes 

W ater d em an d (M l/d ) 

3.50 

3.00 

2.50 

2.00 

1.50 

1.00 

0.50 

0.00 

East Cambs Water Demand Scenarios 

2010/11 

2011/12 

2012/13 

2013/14 

20014/15 

20015/16 

2016/17 

2017/18 

2018/19 

2019/20 

2020/21 

2021/22 

2022/23 

2023/24 

2024/25 

2025/26 

2026/27 

2027/28 

2028/29 

2029/30 

2030/31 

Year 

20,000 

18,000 

16,000 

14,000 

12,000 

10,000 

8,000 

6,000 

4,000 

2,000 

0 

P o p u latio n In crease 

Domestic Population Increase (Cumulative) 

Average AWS metered consumption 

Very High 

As described, towards the end of plan period there is a small deficit in peak demand conditions 

in the Ely planning zone (see Appendix 3 for geographical coverage of this zone) which will 

need a further solution developed in later phases of AWS’s WRMP. Limiting water use at the 

start of the plan period will help to prevent/reduce the need for more additional resource 

transfer. 

Policy and Legislative drivers 

Future Water, the Government’s water strategy for England 41 was published in February 2008 

and lays out the Government’s policies for the future management of water in England. Part of 

its vision is for water efficiency to play a prominent role in achieving a sustainable supply and 

demand balance. 

For relevance to the aspiration of water neutrality, Future Water specifically aims to reduce 

water consumption in existing homes to 130 or 120 l/h/d by 2030. This will require the 

retrofitting of water efficient measures in existing homes and business and behavioural change 

in the use of water and understanding of where it comes from. 

The Building a Greener Future Policy Statement 42 published by Communities and Local 

Government in 2007 gives the target of zero carbon by 2016 (CSH Level 6) for all new homes. 

This will be achieved by a progressive tightening of the Building Regulations. 

The Environment Agency’s Cam and Ely Ouse Catchment Abstraction Management Strategy 43 

(CAMS) states ‘We need to make the best use of our existing water resources. Adopting water 

41 

Future Water, the Government’s water strategy for England, DEFRA, 2008 

42 

Building a Greener Future: policy statement, CLG, 2007, http://www.communities.gov.uk/publications/planningandbuilding/buildinga-greener 

43 

http://www.environment-agency.gov.uk/business/topics/water/119927.aspx 

Low 

Medium 

High


Sept 2011 

65 



efficiency measures can help us achieve this goal. Water efficiency is one of tests that will need 

to be satisfied before we grant a new licence or renew a time limited licence.’ 

East Cambridgeshire Council’s Core Strategy 44 was adopted in October 2009. Policy EN3 of 

the Core Strategy ‘Sustainable construction and energy efficiency’ seeks to Maximising energy 

efficiency and reducing resource consumption in new development schemes, including 

incorporating water efficiency measures 

Climate Change and Availability of Water 

It is predicted that climate change will further reduce the available water resources in East 

Cambridgeshire as rainfall patterns change to less frequent, but more extreme, rainfall events. 

Climate change is thought to be the biggest single risk to water supplies from 2020 and beyond 

in the WRZs within East Cambridgeshire. This could lead to sustainability reductions of 

abstraction licences. 

Managing Climate Change 

In their Strategic Direction Statement, AWS state that climate change is the biggest single risk 

facing their business over the next 25 years. Similarly, in their 2010-2035 WRMP AWS 

highlight that over the planning period one of the key water resources challenges they face are 

from the impacts of climate change. Customers expect AWS to provide a continuous supply of 

water, but the resilience of the supply systems have the potential to be affected by the impact 

of climate change with severe weather-related events, such as flooding or an ‘outage’ incident 

at a source works supplying one of the major centres of population in the region. In their PR09 

submission, AWS addressed the impacts of climate change through the need for investment in 

both mitigation and adaptation, with changes both to long-term averages and short-period 

acute events. 

In planning for future water resources availability, AWS has accounted for the impacts of 

climate change within their calculations of available raw water for use and forecast demand. 

AWS has used assumptions on climate change impacts based on the UKCIP02 scenarios, the 

information on sustainability changes provided at the time by the Environment Agency and the 

Environment Agency’ Water Resources Plan guideline. AWS will be reviewing the more recent 

UKCP09 climate change projections and the outcome of the Habitat’s Directive review of 

consents on their abstraction licences and these will be incorporated into future reviews and 

planning, including the annual review of the WRMP and PR14. 

AWS have reported in their WRMP that the changes that are most significant for managing 

water resources are: 

• the increase in rainfall in the winter; 

• reduction in the summer rainfall; and 

• an increase in summer temperatures that will reduce the length of the winter recharge 

season and potentially increase the demand for water. 

At a strategic level, AWS have highlighted that it will be important to store more run-off from 

winter rainfall and to enhance the natural groundwater recharge. 

AWS have assessed the impacts of climate change on both supply and demand. The main 

findings from these, as included in their WRMP, are summarised below. 

44 http://www.eastcambs.gov.uk/sites/default/files/csadoptmain.pdf

Impact on Supplies 


Sept 2011 

66 



AWS have undertaken analysis of the impacts of climate change on the future availability of 

their water resources on both their groundwater and surface water sources, and incorporated 

these results into their assessment of deployable output. The analysis involved processing 

median, best and worst case scenarios through a number of recognised climate change 

models, for 25 groundwater and 10 surface water sources considered vulnerable to the 

potential impacts of climate change on source yield. The results identified a more significant 

impact on surface water source yield than for groundwater. The modelling results also indicated 

that in some cases potential groundwater yield could increase, as the climate change scenarios 

not only predict higher temperatures but increased periods of prolonged and heavy rainfall. The 

overall impact of climate change on water resources over the plan period is estimated as 

around 30 Ml/d, indicating that small reductions in deployable output at sourceworks level may 

affect local areas of the supply network. 

Impact on Demand 

The main impact of climate change on demand is related to periods of extremely hot and dry 

weather that will increase the peak demand for water. AWS have accounted for the impact on 

the peak demand and the longer duration effect of a dry year through applying factors to the 

household and non-household water consumption rate in their supply-demand modelling. The 

effect of peak demand varies between Water Resource Zones due to factors such as the 

location of holiday resorts and heavy industry and socio-economic factors reflected in the type 

and age of housing stock and customers’ behaviour. 

Although AWS have planned for the anticipated impacts of climate change, the view of AWS 

and other water companies is that, in order to manage the effects of climate change effectively, 

the single most cost effective step in water resources climate change resilience is to manage 

demand downwards. The reduction in demand will also help to reduce carbon emissions which 

aids in reducing impacts of climate change. 

4.3 Ecological Appraisal 

This section discusses the ecological constraints posed by statutory designated sites upon 

increased abstraction for the Public Water Supply within the study area, largely due to their 

susceptibility to low flows. 

The whole of East Cambridgeshire local authority area is supplied by water resources from the 

chalk aquifer in the Cambridgeshire and West Suffolk zone (WRZ9). 

The Fenland and Cambridgeshire & West Suffolk zones are supplied by groundwater via 

boreholes in the Chalk aquifer, although Anglian Water also uses the water resources of the 

sandstone and limestone aquifers in the north. 

Anglian Water’s adopted Water Resource Management Plan (February 2010) identifies those 

water resource zones for which the Environment Agency have imposed sustainability 

reductions in order to avoid an adverse effect on European sites. The sites in question are both 

parts of The Broads SAC and Broadland SPA & Ramsar site - Sheringham and Beeston 

Commons SSSI and Upper Thurne Broads & Marshes SSSI. Both of these are in WRZ6 (North 

Norfolk Coast). The WRMP also identifies those WRZs for which the Environment Agency has 

identified that further studies to investigate impacts on European sites are required - this 

applies to only one Water Resource Zone (WRZ7 – Norfolk Rural) with regard to further studies 

Cavenham & Icklingham Heath.


Sept 2011 

67 



The study area is not linked to either WRZ6 or WRZ7 and therefore these issues can be 

dismissed. 

The WRMP identifies that there are environmental concerns over the impact of abstraction at a 

small number of conservation sites, notably on the edge of the Chalk outcrop in the west of the 

WRZ. The need to investigate concerns on low flows in the upper and lower reaches of the 

River Lark was included in the AMP3 WREP and further work is proposed during AMP5. The 

Cambridgeshire and West Suffolk WRZ is forecast to have a surplus of available against target 

headroom until the last five years of the planning period. Deficits will be met through 

maintaining demand management through leakage control, household metering and the 

promotion of water efficiency and no increases in existing abstraction volumes from sources 

connected with European sites is intended. As such, no adverse effects on European sites are 

anticipated. 

Therefore, while the three WRZs that supply the study area are hydrologically linked to 

European sites (particularly the Ruthamford WRZ which is connected to the Nene Washes 

SAC/SPA & Ramsar site and Ouse Washes SAC/SPA & Ramsar site) and other wildlife sites, 

the information provided in the WRMP indicates that abstractions within the WRZ’s that supply 

the study area are not likely to lead to a significant effect on European sites, following limited 

sustainability reductions that may be required following the completion of the RoC process. 

In correspondence for this Water Cycle Study it is noted in the introduction to the Water Supply 

Strategy chapter that Anglian Water have confirmed that the growth figures assessed for the 

Detailed WCS can be met by the solutions identified within the adopted Water Resource 

Management Plan with the sole exception of the Ely Planning Zone (PZ50) for which it is 

identified that there would be a small deficit towards the end of the plan period. 

Although there is predicted to be a deficit in the last five years this will be addressed through 

mechanisms other than the development of new resources in the WRZ. Existing abstraction 

licences are already subject to evaluation for their impact on nature conservation interests, 

sustainability reductions will have already been factored into the WRMP and no new licences 

are proposed for these WRZ’s in relation to development in East Cambridgeshire. As such, 

there is no reason to conclude that there should be any adverse impact on these sites related 

to the delivery of the WRMP. 

It is noted that Anglian Water state in their adopted WRMP that the Review of Consents 

process is not completed and that further sustainability reductions may be put forward; if so, 

this conclusion may have to be revised but the implication of the WRMP is that Anglian Water 

have taken these possible sustainability reductions into account. 

According to the scoping report, Anglian Water are undertaking a study to investigate the 

potential abstraction impacts on Soham Wet Horse Fen SSSI but this will be completed in 2015 

and impacts on the site cannot be evaluated further until that time. 

4.4 Water Neutrality Pathway 

4.4.1 What is Water Neutrality? 

Water neutrality is a concept whereby the total demand for water within a planning area after 

development has taken place is the same (or less) than it was before development took 

place 45 . If this can be achieved, the overall balance for water demand is ‘neutral’, and there is 

considered to be no net increase in demand as a result of development. In order to achieve 

45 Water Neutrality is defined more fully in the Environment Agency report ‘Towards water neutrality in the Thames Gateway’ (2007)


Sept 2011 

68 



this, new development needs to be subject to planning policy which aims to ensure that where 

possible, houses and businesses are built to high standards of water efficiency through the use 

of water efficient fixtures and fittings, and in some cases rainwater harvesting and greywater 

recycling. 

It is theoretically possible that neutrality can be achieved within a new development area, 

through the complete management of the water cycle within that development area. In addition 

to water demand being limited to a minimum, it requires: 

• All wastewater to be treated and re-used for potable consumption rather than discharged to 

the environment; 

• maximisation of rainwater harvesting (in some cases complete capture of rainfall falling 

within the development) for use in the home; and 

• abstraction of local groundwater or river flow storage for treatment and potable supply. 

Achieving ‘total’ water neutrality within a development remains an aspirational concept and is 

usually only considered for an eco-town or eco-village type development, due to the 

requirement for specific catchment conditions to supply raw water for treatment and significant 

capital expenditure. It also requires specialist operational input to maintain the systems such 

as wastewater re-use on a community scale. Total neutrality for a single development site is 

yet to be achieved in the UK, although there are examplar ecotowns and eco-settlements such 

as Rackheath in Norfolk where it is an aspiration that is being worked towards. 

For the majority of new development, in order for the water neutrality concept to work, the 

additional demand created by new development needs to be offset in part by reducing the 

demand from existing population and employment. Therefore, a ‘planning area’ needs to be 

considered where measures are taken to reduce existing or current water demand from the 

current housing and employment stock. The planning area in this case is considered to be the 

East Cambridgeshire District as a whole. 

The Twin-track approach 

Attainment of water neutrality requires a ‘twin track’ approach whereby water demand in new 

development is minimised as far as possible, whilst at the same time taking measures, such as 

retrofitting of water efficient devices on existing homes and business to reduce water use in 

existing development. 

In order to reduce water consumption and manage demand for the limited water resources 

within the study area, a number of measures and devices are available 46 , including: 

• cistern displacement devices; 

• flow regulation; 

• greywater recycling; 

• low or variable flush replacement toilets; 

• low flow showers; 

• metering; 

• point of use water heaters; 

46 Source: Water Efficiency in the South East of England, Environment Agency, April 2007.

• pressure control; 

• rainwater harvesting; 

• variable tariffs; 

• low flows taps; 

• water audits; 

• water butts; 

• water efficient garden irrigation; and 

• water efficiency promotion and education. 


Sept 2011 

69 



The varying costs and space and design constraints of the above mean that they can be 

divided into two categories, measures that should be installed for new developments and those 

which can be retrofitted into existing properties. For example, due to economies of scale, to 

install a rainwater harvesting system is more cost effective when carried out on a large scale 

and it is therefore often incorporated into new build schools, hotels or other similar buildings. 

Rainwater harvesting is less well advanced as part of domestic new builds, as the payback 

periods are longer for smaller systems and there are maintenance issues. To retrofit a 

rainwater harvesting system can have very high installation costs, which reduces the feasibility 

of it. 

However, there are a number of the measures listed above that can be easily and cheaply 

installed into existing properties, particularly if part of a large campaign targeted at a number of 

properties. Examples of these include the fitting of dual-flush toilets and low flow showers 

heads to social housing stock, as was successfully carried out in Preston by Reigate and 

Banstead Council in conjunction with Sutton and East Surrey Water and Waterwise 47 . 

Achieving Total Neutrality – is it feasible? 

Even when considering neutrality within an existing planning area, it is recognised by the 

Environment Agency (2009) 48 that achievement of total water neutrality (100 per cent) for new 

development is often not possible, as the levels of water savings required in existing stock may 

not be possible for the level of growth proposed. A lower percentage of neutrality may 

therefore be a realistic target, for example 50 per cent neutrality. 

This Stage 2 WCS therefore considers four water neutrality targets and sets out a ‘pathway’ for 

how the most likely target (or level of neutrality) can be achieved. 

4.4.2 The Pathway concept 

The term ‘pathway’ is used here as it is acknowledged that, to achieve any level of neutrality, a 

series of steps are required in order to go beyond the minimum starting point for water 

efficiency which is currently mandatory for new development under current and planned 

national planning policy and legislation. 

Whilst it is compulsory that all new homes are given a rating under the Government’s Code for 

Sustainable Homes (CSH), only affordable housing has a minimum rating that must be 

achieved (Code Level 3); there is no statutory requirement under the Code for all other new 

housing to have a low water use specification as previous government proposals to make 

47 Preston Water Efficiency Report, Waterwise, March 2009, www.waterwise.org.uk 

48 Environment Agency (2009) Water Neutrality, an improved and expanded water management definition


Sept 2011 

70 



different levels compulsory have been postponed pending government review. For nondomestic 

development, there is no statutory requirement to have a sustainability rating with the 

Building Research Establishment Environmental Assessment Method (BREEAM) only being 

mandatory where specified by a public body in England such as: 

• Local Authorities incorporating environmental standards as part of supplementary planning 

guidance; 

• NHS buildings for new buildings and refurbishments; 

• Department for Children, Schools and Families for all projects valued at over £500K (primary 

schools) and £2million (secondary schools); 

• English Partnerships (now incorporated into the Homes and Communities Agency) for all 

new developments involving their land; and 

• Office of Government Commerce for all new buildings; 

At the time of completing this WCS, regional planning policies on water efficiency are also set 

to be withdrawn as part of the proposed revocation of the East of England plan through the 

proposed Localism Bill. 

Therefore, other than potential local policies delivered through the LDF process, the only water 

efficiency requirements for new development are through the Building Regulations 49 where new 

homes must be built to specification to restrict water use to 125l/h/d. However, the key aim of 

the Localism Bill is to decentralise power away from central government towards local 

authorities and the communities they serve. It therefore creates a stronger driver for local 

authorities such as East Cambridgeshire to propose local policy to address specific local 

concerns. New local level policy is therefore key to delivering aspirations such as water 

neutrality and the proposed Localism Bill will assist in providing the legislative mechanism to 

achieve this in East Cambridgeshire. 

In addition to the steps required in new local policy, the use of a pathway to describe the 

process of achieving water neutrality is also relevant to the other elements required to deliver it, 

as it describes the additional steps required beyond ‘business as usual’ that both developers 

and stakeholders with a role (or interest) in delivering water neutrality would need to take e.g. 

• the steps required to deliver higher water efficiency levels on the ground (for the developers 

themselves); and 

• the partnership initiative that would be required beyond that normally undertaken by local 

authorities and water companies in order to minimise existing water use from the current 

housing and business stock. 

Therefore, the pathway to neutrality described in this section of the WCS requires a series of 

steps covering: 

• technological inputs in terms of physically delivering water efficiency measures on the 

ground; 

• local planning policies which go beyond national guidance; and 

• partnership initiatives and partnership working. 

The following sections outline the types of water efficiency measures which have been 

considered in developing the technological pathway for the water neutrality target scenarios. 

49 Part G of the Building Regulations

4.4.3 Improving Efficiency in Existing Development 

Metering 


Sept 2011 

71 



The installation of water meters in existing housing stock has the potential to generate 

significant water use reductions because it gives customers a financial incentive to reduce their 

water consumption. Being on a meter also encourages the installation and use of other water 

saving products, by introducing a financial incentive and introducing a price signal against 

which the payback time of new water efficiency measures can be assessed. Metering typically 

results in a 5-10 per cent reduction from unmetered supply, which equates to a water saving of 

approximately 14.56 l/h/d or 33.5 l per household, assuming occupancy rate of 2.3 50 for existing 

properties. 

In 2009, DEFRA instructed Anna Walker (the Chair of the Office of Rail Regulation) to carry out 

an independent review of charging for household water and sewerage services (the Walker 

Review) 51 . The typical savings in water bills of metered and unmetered households were 

compared by the Walker review, which gives an indication of the levels of water saving that can 

be expected (see Table 4-2). 

Table 4-2: Change in typical metered and unmetered household bills 

2009-10 

Metered 

2009-10 

Unmetered 

2014-15 

Metered 

2014-15 

Unmetered 

% change 

Metered 

% change 

Unmetered 

348 470 336 533 -3 13 

Low or variable flush toilets 

Toilets use about 30 per cent of the total water used in a household 52 . An old style single flush 

toilet can use up to 13 litres of water in one flush. New, more water-efficient dual-flush toilets 

can use as little as 2.6 litres 53 per flush. A study carried out in 2000 by Southern Water and the 

Environment Agency 54 on 33 domestic properties in Sussex showed that the average dual flush 

saving observed during the trial was 27 per cent, equivalent to a volumetric saving of around 

2.6 litres per flush. The study suggested that replacing existing toilets with low or variable flush 

alternatives could reduce the volume of water used for toilet flushing by approximately 27 per 

cent on average. 

Cistern displacement devices 

These are simple devices which are placed in the toilet cistern by the user, which displace 

water and therefore reduce the volume that is used with each flush. This can be easily installed 

by the householder and are very cheap to produce and supply. Water companies and 

environmental organisations often provide these for free. 

Depending on the type of devices used (these can vary from a custom made device, such bag 

filled with material that expands on contact with water, to a household brick) the water savings 

can be up to 3 litres per flush. 

50 

2.3 is used for existing properties as opposed to 2.1 for new properties – the latter reflects changes in population over time. This 

figure was discussed and agreed with AWS prior to the assessment. 

51 

Independent Walker Review of Charging and Metering for Water and Sewerage services, DEFRA, 2009, 

http://www.defra.gov.uk/environment/quality/water/industry/walkerreview/ 

52 

http://www.waterwise.org.uk/reducing_water_wastage_in_the_uk/house_and_garden/toilet_flushing.html 

53 

http://www.lecico.co.uk/ 

54 

The Water Efficiency of Retrofit Dual Flush Toilets, Southern Water/Environment Agency, December 2000

Low flow taps and showers 


Sept 2011 

72 



Flow reducing aerating taps and shower heads restrict the flow of water without reducing water 

pressure. Thames Water estimates that an aerating shower head can cut water use by 60 per 

cent with no loss of performance 55 . 

Pressure control 

Reducing pressure within the water supply network can be an effective method of reducing the 

volume of water supplied to customers. However, many modern appliances, such as Combi 

boilers, point of use water heaters and electric showers require a minimum water pressure to 

function. Careful monitoring of pressure is therefore required to ensure that a minimum water 

pressure is maintained. For areas which already experience low pressure (such as those areas 

with properties that are included on a water company’s DG2 Register) this is not suitable. 

Limited data is available on the water savings that can be achieved from this method. 

As concluded in the Outline Study report, AWS are already proposing pressure control 

measures in WRZs within East Cambridgeshire as part of their WRMP to increase available 

supply to 2035. Further reductions are not considered possible without affecting the DG2 

register. 

Variable tariffs 

Variable tariffs can provide different incentives to customers and distribute a water company’s 

costs across customers in different ways. 

The Walker review assessed variable tariffs for water, including: 

• rising block tariff; 

• a declining block tariff; 

• a seasonal tariff; and 

• time of day tariff. 

A rising block tariff increases charges for each subsequent block of water used. This can raise 

the price of water to very high levels for customers whose water consumption is high, which 

gives a financial incentive to not to consume additional water (for discretionary use, for 

example) while still giving people access to low price water for essential use. 

A declining block tariff decreases charges for each subsequent block of water used. This 

reflects the fact that the initial costs of supply are high, while additional supply has a marginal 

additional cost. This is designed to reduce bills for very high users and although it weakens 

incentives for them to reduce discretionary water use, in commercial tariffs it can reflect the 

economies of scale from bulk supplies. 

A seasonal tariff reflects the additional costs of summer water supply and the fact that fixed 

costs are driven largely by the peak demand placed on the system, which is likely to be in the 

summer. 

Time-of-day tariffs have a variable cost per unit supply according to the time of the day when 

the water is used; this requires smart meters. This type of charging reflects the cost of water 

55 http://www.thameswater.co.uk/cps/rde/xchg/corp/hs.xsl/9047.htm


Sept 2011 

73 



supply and may reduce an individual household’s bill, it may not reduce overall water use for a 

customer. 

AWS’s WRMP 56 reviewed variable tariffs and concluded: 

‘Tariff proposals will only work if customer behaviour and demand is elastic. We carried out 

research as part of the last Periodic Review to draw together evidence of price elasticity from 

around the world. The results gave us some clear messages. First, demand tends to be elastic 

for large industrial customers, but much less elastic for small household customers. Second, 

demand tends to be elastic in countries such as Australia, where the discretionary use of water 

is high, but is low in the UK where discretionary use is a relatively small proportion of total 

water use. This leads us to conclude that increasing the marginal price of water and 

wastewater services would have some impact on our largest customers, but would tend to have 

a limited effect on household water consumption either by affecting total demand or by 

influencing peak profiles. We consider that customer behaviour can be influenced more 

effectively by promoting ‘Waterwise’ behaviour rather than by changing the way customer 

charges are applied.’ 

Water efficient appliances 

Washing machines and dishwashers have become much more water efficient over the past 

twenty years; whereas an old washing machine may use up to 150 litres per cycle, modern 

efficient machines may use as little as 35 litres per cycle. An old dishwasher could use up to 50 

litres per cycle, whereas modern models can use as little as 10 litres. However, this is partially 

offset by the increased frequency with which these are now used. It has been estimated 57 that 

dishwashers, together with the kitchen tap, account for about 8-14 per cent of water used in the 

home. 

The Water Efficient Product Labelling Scheme provides information on the water efficiency of a 

product (such as washing machines) and allows the consumer to compare products and select 

the efficient product. The water savings from installation of water efficient appliances therefore 

vary, depending on the type of machine used. 

Non-domestic Properties 

There is also the potential for considerable water savings in non-domestic properties; 

depending on the nature of the business water consumption may be high e.g. food processing 

businesses. Even in businesses where water use is not high, such as B1 Business or B8 

Storage and Distribution, there is still the potential for water savings using the retrofitting 

measures listed above in section 2.2.1. Water audits are useful methods of identifying potential 

savings and implementation of measures and installation of water saving devices could be 

funded by the asset owner; this could be justified by significant financial savings which can be 

achieved through implementation of water efficient measures. Non-domestic buildings such as 

warehouses and large scale commercial (e.g. supermarkets) property have sinifican scope for 

rainwater harvesting on large roof areas. 

There is significant potential for water efficiency in the agricultural sector from rainwater 

harvesting. The Environment Agency guide for farmers 58 illustrates the potential benefits to 

both the environment and the farmer from the installation of a RWH system. For example, a 

56 

Anglian Water Services, Water Resource Management Plan, 2010, http://www.anglianwater.co.uk/environment/waterresources/resource-management/ 

57 

Water Efficiency Retrofitting: A Best Practice Guide, Waterwise, 2009, www.waterwise.org.uk 

58 Rainwater Harvesting: an on-farm guide, Environment Agency, 2009


Sept 2011 

74 



farm growing soft fruit in polytunnels could harvest 5,852 m 3 of water per year from 120 

hectares of tunnels, which could give the following benefits: 

• better soil drainage between the tunnels, 

• improved humidity levels inside them; and 

• an improvement in plant health through the use of harvested water. 

4.4.4 Water Efficiency in New Development 

The use of efficient fixtures and fittings as described in section 4.4.3 above also apply to the 

specification of water use in the building of new homes. The simplest way of demonstrating the 

reductions that use of efficient fixtures and fitting has in new builds is to consider what is 

required in terms of installation of the fixtures and fittings at different ranges of specification to 

ensure attainment of code levels under the CSH water use requirements. The Cambridge 

WCS 59 gave a summary of water use savings that can be achieved by the use of efficient 

fixtures and fittings, as shown below in Table 4-3. 

Table 4-3: Summary of water savings borne by water efficiency fixtures and fittings 

Component 150 l/h/d 

Standard 

Home 

Toilet 

flushing 

130 l/h/d 120 l/h/d 

CSH1/2 

115 l/h/d 105 l/h/d 

CSH Level 

3/4 

80 l/h/d 

CSH Level 

5/6 

28.8 19.2 b 19.2 b 16.8 d 16.8 d 8.4 + 8.4 f 

Taps a 42.3 42.3 31.8 31.8 24.9 18 

Shower 30 24 24 22 18 18 

Bath 28.8 25.6 c 25.6 c 25.6 c 25.6 c 22.4 e 

Washing 

machine 

16.7 15.3 15.3 15.3 15.3 7.65 + 7.65 f 

Dishwasher 3.9 3.6 3.6 3.6 3.6 3.6 

Recycled 

water 

Total per 

head 

150.5 130 119.5 115.1 104.2 78 

-16.1 

Outdoor 11.5 11.5 11.5 11.5 11.5 11.5 

Total per 

household 

366.68 319.3 293.52 284.14 257.41 195.58 

a Combines kitchen sink and wash hand basin 

b 6/3 litre dual-flush toilet (f) recycled water 

c 160 litre bath filled to 40% capacity, frequency of use 0.4/day 

d 4.5/3 litre dual flush toilet 

e 120 litre bath 

f rainwater/greywater harvesting) 

59 Cambridge (and surrounding major growth areas) WCS Phase 2, Halcrow, 2010

g Assumed garden use 


Sept 2011 

75 



Table 4-3 highlights that in order for code levels 5/6 to be achieved for water use under the 

CSH (80 l/h/d), water re-use technology (rainwater harvesting and/or greywater recycling) 

needs to be incorporated into the development. In using the BRE Water Demand Calculator 60 , 

the experience of URS/Scott Wilson BREEAM/CHS assessors is that it is theoretically possible 

to get close to 80l/h/d through the use of fixture and fittings, but that this requires extremely 

high specification efficiency devices which are unlikely to be acceptable to the user and will 

either affect the saleability of new homes or result in the immediate replacement of the fixtures 

and fittings upon habitation. This includes baths at capacity below 120 litres, and shower 

heads with aeration which reduces the pressure sensation of the user. For this reason, it is not 

considered practical to suggest that code levels 5 and 6 can be reached without some form of 

water recycling. 

Rainwater Harvesting 

Rainwater harvesting (RWH) is the capture and storage of rain water that lands on the roof of a 

property. This can have the dual advantage of both reducing the volume of water leaving a site, 

thereby reducing surface water management requirements and potential flooding issues, and 

be a direct source of water, thereby reducing the amount of water that needs to be supplied to 

a property from the mains water system. 

RWH systems typically consist of a collection area (usually a rooftop), a method of conveying 

the water to the storage tank (gutters, down spouts and pipes), a filtration and treatment 

system, a storage tank and a method of conveying the water from the storage container to the 

taps (pipes with pumped or gravity flow). A treatment system may be included, depending on 

the rainwater quality desired and the source. Figure 4-1 below gives a diagrammatic 

representation of a typical domestic system 61 . 

The level to which the rainwater is treated depends on the source of the rainwater and the 

purpose for which it has been collected. Rainwater is usually first filtered to remove larger 

debris such as leaves and grit. A second stage may also be incorporated into the holding tank; 

some systems contain biological treatment within the holding tank, or flow calming devices on 

the inlet and outlets will allow heavier particles to sink to the bottom, with lighter debris and oils 

floating to the surface of the water. A floating extraction system can then allow the clean 

rainwater to be extracted from between these two layers 62 . 

A recent sustainable water management strategy carried out for a proposed EcoTown 

development at Northstowe 63 , approximately 10 km to the north west of Cambridge, calculated 

the size of rainwater storage that may be required for different occupant numbers, as shown 

below in Table 4-4. 

60 http://www.thewatercalculator.org.uk/faq.asp 

61 Source: Aquality Intelligent Water management, www.aqua-lity.co.uk 

62 Aquality Rainwater Harvesting brochure, 2008 

63 Sustainable water management strategy for Northstowe, WSP, December 2007

Figure 4-1: A typical domestic rainwater harvesting system 

Table 4-4: RWH systems sizing 

Number of 

occupants 


Sept 2011 

Total water 

consumption 

Roof area 

(m 2 ) 

76 

Required 

storage tank 

(m 3 ) 



Potable 

water 

saving 

per head 

(l/d) 

Water 

consumption 

with RWH 

(l/h/d) 

1 110 13 0.44 15.4 94.6 

1 110 10 0.44 12.1 97.9 

1 110 25 0.88 30.8 79.2 

1 110 50 1.32 57.2 52.8 

2 220 25 0.88 15.4 94.6 

2 220 50 1.76 30.8 79.2 

3 330 25 1.32 9.9 100.1 

3 330 50 1.32 19.8 90.2 

4 440 25 1.76 7.7 102.3 

4 440 50 1.76 15.4 94.6 

A family of four, with an assumed roof area of 25 m 3 , could therefore expect to save 61.6 litres 

per day if a RWH system were installed. 

Greywater Recycling


Sept 2011 

77 



Greywater recycling (GWR) is the treatment and re-use of wastewater from shower, bath and 

sinks for use again within a property where potable quality water is not essential e.g. toilet 

flushing. Recycled greywater is not suitable for human consumption or for irrigating plants or 

crops that are intended for human consumption. The source of greywater should be selected 

by available volumes and pollution levels, which often rules out the use of kitchen and clothes 

washing waste water as these tend to be most highly polluted. However, in larger system 

virtually all non-toilet sources can be used, subject to appropriate treatment. 

The storage volumes required for GWR are usually smaller than those required for rainwater 

harvesting as the supply of greywater is more reliable than rainfall. In domestic situations, 

greywater production often exceeds demand and a correctly designed system can therefore 

cope with high demand application and irregular use, such as garden irrigation. Figure 4-2 

below gives a diagrammatic representation of a typical domestic system 64 . 

Figure 4-2: A typical domestic greywater recycling system 

Combined rainwater harvesting and greywater recycling systems can be particularly effective, 

with the use of rainwater supplementing greywater flows at peak demand times (e.g. morning 

and evenings). 

The Northstowe sustainable water management strategy calculated the volumes of water that 

could be made available from the use GWR. These were assessed against water demand 

calculated using the BRE Water Demand Calculator 65 . 

Table 4-5: Potential water savings from GWR 

Appliance Demand with 

Efficiencies 

(l/h/day) 

Potential 

Source 

Greywater 

Required 

(l/h/day) 

Out As Greywater 

available 

(80% 

efficiency) 

(l/h/day) 

Consumptions 

with GWR 

(l/h/day) 

Toilet 15 Grey 15 Sewage 0 0 

Wash hand 

basin 

64 Source: Aquality Intelligent Water management, www.aqua-lity.co.uk 

65 http://www.thewatercalculator.org.uk/faq.asp 

9 Potable 0 Grey 7 9


Sept 2011 

78 



Shower 23 Potable 0 Grey 18 23 

Bath 15 Potable 0 Grey 12 15 

Kitchen Sink 21 Potable 0 Sewage 0 21 

Washing 

Machine 

17 Grey 17 Sewage 0 0 

Dishwasher 4 Potable 0 Sewage 0 4 

Total 103 31 37 72 

The above demonstrates the water savings that can be achieved by GWR. If the toilet and 

washing machine are connected to the GWR system a saving of 37 litres per person per day 

can be achieved. 

The treatment requirements of the GWR system will vary, as water which is to be used for 

flushing the toilet does not need to be treated to the same standard as that which is to be used 

for the washing machine. The source of the greywater also greatly affects the type of treatment 

required. Greywater from a washing machine may contain suspended solids, organic matter, 

oils and grease, detergents (including nitrates and phosphates) and bleach. Greywater from a 

dishwasher could have a similar composition, although the proportion of fats, oils and grease is 

likely to be higher; similarly for wastewater from a kitchen sink. Wastewater from a bath or 

shower will contain suspended solids, organic matter (hair and skin), soap and detergents. All 

wastewater will contain bacteria, although the risk of infection from this is considered to be 

low 66 . 

Treatment systems for GWR are usually of the following four types: 

• basic (e.g. coarse filtration and disinfection); 

• chemical (e.g. flocculation); 

• physical (e.g. sand filters or membrane filtration and reverse osmosis); and 

• biological (e.g. aerated filters or membrane bioreactors). 

4.4.5 Water Neutrality Scenarios 

As described, four water neutrality targets have been proposed and assessed as part of this 

WCS. Each target moves beyond the business as usual scenario which is considered to be: 

• 105l/h/d for new affordable homes 67 and 125 l/h/d for all other new homes 68 ; 

• no mandatory efficiency target for non-domestic property; and 

• continued meter installation in existing homes as planned in AWS’s WRMP up to 2035. 

At 65 per cent, the existing level of metering within the AWS region is already twice the national 

average 69 . AWS’s future target for meter penetration 70 is 90 per cent penetration on domestic 

water meters by 2035. During AMP4 (from 2005-06 to 2009-10 over 100,000 customers opted 

to use a water meter, which when combined approximately 20,000 new metered connections 

each year, resulted in the growth in metered households by 2 per cent year. The WRMP 

assumes this rate will continue to the target of 90% of customers metered by 2035. 

66 

Centre for the Built Environment, www.cbe.org.uk 

67 

Levels 3&4 - CSH 

68 

Building regulations Part G requirement 

69 

(2010), Anglian Water Services- Water Resources Management Plan, Main Report. 

70 

that is the proportion of properties within the AWS supply area which have a water meter installed


Sept 2011 

79 



Therefore, the Water Neutrality scenarios can only assume a further 10% meter penetration 

within the existing housing stock by the end of the plan period in line with AWS’ WRMP. 

The Water neutrality scenarios have been developed based on the following generic 

assumptions. For clarity, the East Cambridgeshire district as a whole has been considered 

when assessing the scenarios: 

Very High Scenario 

The key assumptions for this scenario are: 

• it assumes water neutrality is achieved, however it is considered as aspirational only as it is 

unlikely to be feasible based on: 

• existing research into financial viability of such high levels of water efficiency measures in 

new homes; and 

• Uptake of retrofitting water efficiency measures considered to be at the maximum achievable 

(35%) in the county 71 ; 

• It would require: 

• a significant funding pool and a specific joint partnership ‘delivery plan’ to deliver the 

extremely high percentage of retrofitting measures required; 

• strong local policy within the LDF on restriction of water use in new homes on a district scale 

which is currently unprecedented in the UK; and 

• all new development to include water recycling facilities across the district which is currently 

limited to small scale development in the UK. 

The scenario has been developed as a context to demonstrate what is required to achieve the 

full aspiration of water neutrality. 

High Scenario 


• A high water neutrality percentage 72 is achieved but requires significant funding and 

partnership working, and adoption of new local policy which is currently unprecedented in the 

UK. 


• Uptake of retrofitting water efficiency measures to be very high (25%) in relation to studies 

undertaken across the UK; 

• a significant funding pool and a specific joint partnership ‘delivery plan’ to deliver the high 

percentage of retrofitting measures required; and 

• strong local policy within the LDF on restriction of water use in new homes on a district scale 

which is currently unprecedented in the UK; 

It is considered that, despite being at the upper scale of percentage uptake of retrofitting 

measures, it is technically and politically feasible to obtain this level of neutrality if a fully funded 

joint partnership approach could be developed. 

71 Cambridge (and surrounding major growth areas) WCS Phase 2, Halcrow, 2011 

72 WN percentage refers to the percentage of water use savings made by various measures against the total new demand if the 

business as usual demand were to continue

Medium Scenario 



Sept 2011 

80 



• The water neutrality percentage 73 achieved is approximately 50% of the total neutrality target 

and would require funding and partnership working, and adoption of new local policy which i 

has only been adopted in a minimal number of LDFs in the UK. 


• Uptake of retrofitting water efficiency measures to be reasonably high (20%) in the county 74 

• a significant funding pool and a specific joint partnership ‘delivery plan’ to deliver the high 

percentage of retrofitting measures required; 

• Local policy within the LDF on restriction of water use in new homes on a district scale which 

goes beyond that seen generally in the UK. 

It is considered that it is technically and politically feasible to obtain this level with a relatively 

modest funded joint partnership approach and with new developers contributing relatively 

standard, but high spec water efficient homes 

Low Scenario 


• The water neutrality percentage 75 achieved is low but would require small scale level of 

funding and partnership working, and adoption of new local policy which is likely to be easily 

justified and straightforward for developers to implement; and 


• Uptake of retrofitting water efficiency measures to be fairly low (10%); 

• a relatively small funding pool and a partnership working not moving too far beyond business 

as usual for stakeholders; and 

• Local policy within the LDF on restriction of water use would be easy to justify and 

implement. 

It is considered that it is technically and politically straightforward to obtain this level with a 

small funded joint partnership approach and with new developers contributing standard, but 

water efficient homes with a relative low capital expenditure. 

Neutrality Scenario Assessment Results 

For each neutrality scenario, an outline of the required water efficiency specification was 

developed for new houses, combined with an estimate of the savings that could be achieved 

through metering and further savings that could be achieved via retrofitting of water efficient 

fixtures and fittings in existing property. This has been undertaken utilising research 

undertaken by groups and organisations such as Waterwise East, UKWIR 76 , the Environment 

Agency and Ofwat to determine realistic and feasible efficiency savings as part of developer 

design of properties, and standards for non-residential properties. 

73 

WN percentage refers to the percentage of water use savings made by various measures against the total new demand if the 

business as usual demand were to continue 

74 

Cambridge (and surrounding major growth areas) WCS Phase 2, Halcrow, 2011 

75 

WN percentage refers to the percentage of water use savings made by various measures against the total new demand if the 

business as usual demand were to continue 

76 

UKWIR – The United Kingdom Water Industry Research group, attended and part funded by all major UK water companies


Sept 2011 

81 



To achieve total neutrality, the demand post growth must be the same as, or less than existing 

demand. Based on estimates of population size, existing demand in East Cambridgeshire was 

calculated to be 12.25 Ml/d. 

For each neutrality scenario, total demand was then calculated at three separate stages for 

housing and employment as follows: 

• Stage 1 – total demand post growth without any assumed water efficiency retrofitting for the 

differing levels of water efficiency in new homes; 

• Stage 2 – total demand post growth with effect of metering applied for the differing levels of 

water efficiency in new homes; and 

• Stage 3 – total demand post growth with metering and water efficient retrofitting applied to 

existing homes for the differing levels of water efficiency in new homes. 

The results are shown in Table 4-6. If neutrality is achieved, the result is displayed as green. If 

it is not, but within 20%, it is displayed as amber, and red if not achieved. The percentage of 

total neutrality achieved per scenario is also provided. 

Table 4-6: Results of the neutrality scenario assessments 

New homes & employment demand 

Projections 

Demand 

(Ml/d) 

Total demand 

post growth 

(Ml/d) 

Total demand after 

metering effect 

(Ml/d) 

Total demand after 

metering & WE F&F 

(Ml/d) 

% neutrality 

achieved 

Existing Demand 12.25 12.25 

Average AWS metered consumption 2.91 15.16 14.79 14.79 -1.10% 

Business as usual 2.52 14.77 14.28 14.28 19.19% 

Low 2.42 14.67 14.18 14.10 26.29% 

Medium 2.12 14.36 13.88 13.40 54.22% 

High 1.59 13.84 13.36 12.37 95.06% 

Very High 1.25 13.50 13.02 11.64 124.29% 

* prior to demand management for existing stock 

The results show that total neutrality is achieved only by applying the very high scenario, whilst 

the high neutrality scenario gives 95% neutral water use. 

4.4.6 Delivery Requirements - Technological 

The details of what is required technologically from each scenario in terms of new build is 

included in Table 4-7.

Table 4-7: Details of new Build Specification to meet each water use target 

Component 150 l/h/d 

Standard 

Home 


Sept 2011 

Business as 

usual 

82 

Low (120 l/h/d target 

CSH 1/2) 



Medium (105 l/h/d 

CSH Level 3/4) 

High (80 l/h/d 

target CfSH 

Level 5/6) 

very High 

Toilet flushing 28.8 19.2 19.2 16.8 16.8 16.8 

Taps 42.3 31.8 31.8 24.9 18 18 

Shower 30 30 24 18 18 18 

Bath 28.8 25.6 25.6 25.6 22.4 22.4 

Washing machine 16.7 15.3 15.3 15.3 15.3 15.3 

Dishwasher 3.9 3.9 3.6 3.6 3.6 3.6 

Recycled water -16.1 -32.2 

Total per head 150.5 125.8 119.5 104.2 78 61.9 

Total per household 316.05 264.18 250.95 218.82 163.8 129.99 

COLOUR KEY 

Combines kitchen sink and wash hand basin 

6/3 litre dual-flush toilet (f) recycled water 

160 litre bath filled to 40% capacity, frequency of 

use 0.4/day 

4.5/3 litre dual flush toilet 

120 litre bath 

Rainwater harvesting 

rainwater harvesting & greywater for toilet 

flushing and washing machine 

Table 4-8 below gives further detail on the measures required in new builds and from 

retrofitting, including assumptions on the predicted uptake of retrofitting from the existing 

housing and commercial building use.

Table 4-8: Water Neutrality Scenarios – specific requirements for each scenario 

WN 

Scenario 

Business 

as usual 

New 

development 

Water use 

target (l/h/d) 

125 


Sept 2011 

Relevant 

CSH 

target 

Building 

Regs 

only 

Low 120 Level 1/2 

Medium 105 Level 3/4 

High 78 Level 5/6 

Very 

High 

62 Level 5/6 

83 



New development requirement Retrofitting existing development 

Water Efficient Fixtures and 

Fittings 

- 3-6 litre dual flush toilet; 

- Low aeration taps; 

- 160 litre capacity bath; 

- High efficiency washing machine 

- 3-6 litre dual flush toilet; 

- Low spec aeration taps; 


- low spec low flow shower head 

- High efficiency dishwasher 


- 3-4.5 litre dual flush toilet; 

- Medium spec aeration taps; 

- high spec low flow shower head; 


- high spec flow shower head 



- 3-4.5litre dual flush toilet; 

- High spec aeration taps; 



- high spec low flow shower head 



- 3-4.5litre dual flush toilet; 

- High spec aeration taps; 


Water Recycling 

technology 

None 

Metering 

Penetration 

assumption a 

90% 

None 100% 

None 100% 

Rainwater 

harvesting 

Rainwater 

harvesting and 

Greywater 

100% 

100% 


Fittings 

None 

- 3-6 litre dual flush toilet or 

cistern device fitted; 

- 10% take up across district 

- 3-4.5 litre dual flush toilet or 


- medium spec aerated taps fitted 




- high spec aerated taps fitted 


fitted 




- high spec aerated taps fitted

WN 

Scenario 

New 

development 

Water use 

target (l/h/d) 


Sept 2011 

Relevant 

CSH 

target 

84 



New development requirement Retrofitting existing development 


Fittings 






technology 

• a: only the additional metering beyond business as usual has been accounted for (i.e. 10%) 

• b: refers to fittings above that included in a standard home using approximately 150l/h/d 

Metering 

Penetration 

assumption a 


Fittings 

recycling - high spec low flow shower head 

fitted 

- 35% take up across district

Financial Cost considerations 


Sept 2011 

85 



The financial cost of delivering the technological requirements of each neutrality scenario have 

been calculated from available research and published documents. 

New Build Costs 

Costs for water efficiency in new property have been provided based on homes achieving 

different code levels under the CSH based on the cost analysis undertaken by CLG 77 and as 

set out in Table 4-9. 

Table 4-9: CSH Specifications and Costs 

An additional cost was required for the ‘very high’ neutrality scenario that included for 

greywater recycling as well as rainwater harvesting and this is detailed in the following section. 


Research into the financial costs of installing and operating GWR systems gives a range of 

values, as follows: 

Table 4-10: Costs of GWR systems 

Cost Cost Comments 

Installation cost £1,750 

£2,000 

£800 

£2,650 

77 CLG (2008) cost analysis of he Code for Sustainable Homes 

Cost of reaching Code Level 5/6 for water consumption in a 2bed 

flat 78 

For a single dwelling 79 

Cost per house for a communal system 80 

Cost of reaching Code Level 3/4 for water consumption in a 3bed 

semi-detached house 81

Operation of GWR £30 per annum 82 


Sept 2011 

86 



Replacement costs £3,000 to replace 23 It is assumed a replacement system will be required every 25 

years 

There is less research and evidence relating to the cost of community scale systems compared 

to individual household systems, but it is thought that economies of scale will mean than larger 

scale systems will be cheaper to install than those for individual properties. As shown above, 

the Cost review of the Code for Sustainable Homes indicated that the cost of installing a GWR 

system in flats is less than the cost for a semi-detached house. Similarly, the Water Efficient 

Buildings website estimates the cost of installing a GWR system to be £2,000 for a single 

dwelling and £800 per property for a share of a communal system. 

As it is not possible to determine how many of the outstanding housing developments in East 

Cambridgeshire will be of a size large enough to consider communal recycling facilities, an 

approximation has been made of an average per house cost (£1,400) using the cost of a single 

dwelling (at £2,000) and cost for communal (at £800). This has been used for the assessment 

of cost for a greywater system in a new property required for the ‘very high’ neutrality scenario. 

Installing a meter 

The cost of installing a water meter has been assumed to be £500 per property 83 . It is assumed 

that the replacement costs will be the same as the installation costs (£500), and that meters 

would need to be replaced every 15 years 84 . 

Retrofitting of water efficient devices 

Findings from the Environment Agency report Water Efficiency in the South East of England 85 , 

costs have been used as a guide to potential costs of retrofitting of water efficient fixtures and 

fittings and are presented in Table 4-11 below. 

Table 4-11: Water Saving Methods 

Water Saving 

Method 

Variable flush retrofit 

toilets 

Low flow shower 

head scheme 

Approximate Cost 

per House (£) 

Comments/uncertainty 

£50 - £140 Low cost for 3-6 litre system and high cost 

for 3-4.5 litre system. Needs incentive to 

replace old toilets with low flush toilets. 

£15 - £50 Low cost for low spec shower head; high 

costs for high spec. Cannot be used with 

electric, power or low pressure gravity fed 

systems. 

Aerating taps £10 - £20 Low cost is med spec, high cost is high 

spec. 

78 

Code for Sustainable Homes: A Cost Review, Communities and Local Government, 2008 

79 

http://www.water-efficient-buildings.org.uk/?page_id=1056 

80 

http://www.water-efficient-buildings.org.uk/?page_id=1056 

81 

Code for Sustainable Homes: A Cost Review, Communities and Local Government, 2008 

82 

Environment Agency Publication - Science Report – SC070010, Greenhouse Gas Emissions of Water Supply and Demand 

Management Options, 2008 

83 


84 

Environment Agency Publication - Science Report – SC070010: Greenhouse Gas Emissions of Water Supply and 

Demand Management Options, 2008 

85 Ref – Water Efficiency in the South East of England


Sept 2011 

87 



Toilet cistern displacement devices are often supplied free of charge by water companies and 

this is therefore also not considered to be an additional cost. 

Neutrality scenario costs 

Using the above information, the financial costs per scenario has been calculated and are 

included in Table 4-12.

Table 4-12: Estimated Cost of Neutrality Scenarios 


Sept 2011 

88 



Neutrality 

Scenaro 

CSH - Code Level 

Outstanding housing 

Numbers CSH cost 

No. to be metered 

(10% of existing ) 

Existing properties 

Metering cost Retrofit % 

No's to 

retrofit 

Retrofit cost Developer 

Costs Summary 

Non developer Total 

Low 1 or 2 9,222 £ - 3,550 £ 1,775,000 10.00% 3550 £ 177,500 £ - £ 1,952,500 £ 1,952,500 

Medium 3 or 4 9,222 £ 1,152,750 3,550 £ 1,775,000 20.00% 7100 £ 1,171,500 £ 1,152,750 £ 2,946,500 £ 4,099,250 

High 5 or 6 (RWH) 9,222 £ 24,392,190 3,550 £ 1,775,000 25.00% 8875 £ 1,952,500 £ 24,392,190 £ 3,727,500 £ 28,119,690 

Very High 5 or 6 (RWH & GWR) 9,222 £ 36,934,110 3,550 £ 1,775,000 35.00% 12425 £ 2,733,500 £ 36,934,110 £ 4,508,500 £ 41,442,610

Carbon Cost considerations 


Sept 2011 

89 



As described in this section, there are sustainability issues to consider when deciding on a 

policy for promotion of water neutrality. Reaching the very highest levels of efficiency requires 

the use of recycling technology (either through rainwater harvesting and treatment or greywater 

recycling) which requires additional energy both embedded in the physical structures required 

and also in the treatment process required to make the water usable. 

Whilst being water efficient is a key consideration of this study, due to the wider vision for 

sustainable growth, reaching neutrality should not be at the expense of increasing energy use 

and potential increasing the carbon footprint of development 

It is also important to consider that through using less water, more water efficient homes 

require less energy to heat water, hence there are energy savings. 

In order to give an overview of the likely sustainability of each of the WN scenarios, a ‘carbon 

cost’ has been applied to each of the scenarios based on the water efficiency measures 

proposed for new homes, and the retrofitting of existing. 

Methodology 

A joint study by the Environment Agency and the Energy Saving Trust 86 assessed the energy 

and carbon implications of the installation of water saving devices. The report initially calculated 

a baseline water consumption figure for existing housing stock, using the following 

assumptions: 

Table 4-13: Baseline energy consumption assumptions 

Device Volume of water per use (litres) Frequency of use (per person 

per day) 

Toilet 9.4 4.66 

Kitchen Taps 59 Taps taken as 

volume/day, 40% cold 

Basin taps hot 42 Taps taken as 

volume/day, 30% cold 

Bath 70 0.21 

Washing machine 50 0.34 

Shower 25.7 0.59 

Dishwasher 21.3 0.29 

The study then modelled the CO2 emissions from this ‘standard’ existing dwelling, as shown 

below in Figure 4-3. Appliances requiring hot water using appliances dominate, but water use 

for toilet flushing produces 53kg of CO2 emissions per year (approximately 50 per cent from 

water company emissions and 50 per cent due to heat loss as cold mains water in the toilet 

cistern heats to room temperature). 

86 Quantifying the energy and carbon effects of water saving, Full technical report, Environment Agency and the Energy Saving Trust, 

2009

Figure 4-3: CO2 emissions from a ‘standard’ existing dwelling 


Sept 2011 

90 



The study then assessed the impacts on this baseline figure of 681 kg CO2 for water use from a 

home which has water use compliant with CfSH level 3/4. 

Figure 4-4: CO2 emissions from a CfSH Level 3/4 dwelling 

The study then assessed the impacts of a home which has water use compliant with CfSH level 

5/6.

Figure 4-5: CO2 emissions from a CfSH Level 5/6 dwelling 


Sept 2011 

91 



It can therefore be seen that the carbon cost of achieving Levels 3/4 and 5/6 compares 

favourably to the baseline scenario of current average water use of 681kg/CO2. CfSH level 3/4 

represents a carbon saving of 99 kg/CO2 and CfSH Level 5/6 represents a carbon saving of 

150 kg/CO2. 

The energy savings from water efficiency measures within the home would be offset to a 

certain degree by increased energy demands of RWH or GWR systems, which have been 

shown to be required to meet CfSH Level 5/6. Energy savings for AWS from not treating 

additional water to potable standard, as with the conventional mains water supply, can be 

thought of to be simply a transfer of energy consumption away from the AWS to the individual 

householders. While AWS will benefit from this reduction in energy demand, which will assist 

with meeting its Carbon Reduction Commitment (CRC) (as laid down in 2007’s Energy 

Reduction White Paper 87 ), the expense will be passed to householders. 

For households with the GWR/RWH required for CfSH Levels 5/6, any financial benefits to 

householders experienced through a reduction in water bills (for metered properties) will be 

offset by the increased expense of energy bills for pumping and treating water in GWR and 

RWH systems. 

The WRMP Direction 200788 and WRP Guideline 89 require details of the greenhouse gas 

emissions that are likely to arise through the delivery of a water company’s proposed WRMP. 

AWS estimated these from calculation of greenhouse gases as tonnes of carbon dioxide 

equivalent (tCO2e) for the base year 2007-08 of 143,889 tCO2e for drinking water treatment 

and distribution. For subsequent years the value of 0.34 tCO2e/Ml has been used with the 

forecast demand to give the mass of CO2e likely to be emitted on the basis of current 

technologies. In order to calculate the carbon costs of achieving water efficiency for the 

proposed growth in East Cambridgeshire, the value of 0.34 tCO2e/Ml has been used. 

Results 

87 

Meeting the Energy Challenge - A White Paper on Energy, May 2007, Department of Trade and Industry 

88 

WRMP Regulations Statutory Instrument 2007 No. 727, WRMP Direction 2007, WRMP (No.2) Direction 2007, WRMP (No.2) 

(Amendment) Direction 2007, WRMP Direction 2008 

89 

Water resources planning guideline, Environment Agency, November 2008, http://www.environmentagency.gov.uk/business/sectors/39687.aspx


Sept 2011 

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The information was used along with estimates of energy used in recycling technology 90 to 

provide a carbon cost for each of the WN scenarios for East Cambridgeshire. The results are 

presented in Table 4-14. 

The following assumptions have been applied: 

• under the ‘High’ and ‘Very high’ scenarios, consideration must be taken of carbon use in 

rainwater harvesting as well as water use; 

• A basic assumption that each new home is a 90m2 2-storey house with a small biological 

system; and 

• insufficient information was available to differentiate between energy used in a building 

regulations standard home at 125l/h/d and a code level 1 or 2 home on the CSH. Therefore, 

energy used per home is the same for ‘business as usual (i.e. building regulations) and the 

low WN scenario. 

90 Environment Agency (2010) Energy and carbon implications of rainwater harvesting and greywater recycling

Table 4-14: Carbon costs of WN Scenarios 

WN Scenario Relevant CSH target Water use reduction from retrofit 

per WN scenario (Ml/d) 


Sept 2011 

Carbon reduction 

per WN scenario 

93 

Carbon use per new 

home (kg/y) 

carbon use per new 

home (kg/d) 



Total carbon use for new 

homes in EC (tCO2e/d) 

Total 

tCO2e/d 

Business as usual Building Regs only 0.0000 

(tCO2e/d) 

0 681 1.865753425 17.20597808 17.20598 

Low Level 1/2 0.0784 -0.02665056 681 1.865753425 17.20597808 17.17933 

Medium Level 3/4 0.4801 -0.16323468 582 1.594520548 14.70466849 14.54143 

High Level 5/6 0.9859 -0.335214075 578 1.583561644 14.60360548 14.26839 

Very High Level 5/6 1.3803 -0.469299705 614.9 1.684657534 15.53591178 15.06661 

The results show that there a significant CO 2 savings to be made by homes being built to a higher water efficiency level and from the effect of 

existing homes using less energy to heat water through retrofitting of water efficient devices. 

The additional energy used per house for RWH in the High scenario is offset by the savings made in using less water in line with code levels 5/6 on 

the CSH; however the additional energy required for greywater recycling in the very high scenario makes this scenario higher in CO 2 emissions than 

both the medium and high WN scenarios. This suggests that in order to meet total neutrality there will be an increase in CO 2 emissions over less 

intensive WN scenarios and hence there are concerns over the long term sustainability of pursuing such a strategy,

4.4.7 Preferred strategy – delivery Pathway 


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The stakeholder group has agreed that in order to being the pathway to neutrality, that 

measures are taken to deliver the first step of the ‘low’ WN scenario. This would allow a WN 

target of 25% to be reached and is generally considered to require small scale level of funding 

and partnership working, and adoption of new local policy which is likely to be easily justified 

and straightforward for developers to implement. 

It is considered that, it is technically and politically straightforward to obtain this level with a 

small funded joint partnership approach and with new developers contributing standard, but 

water efficient homes with a relative low capital expenditure 

Depending on the success of the first step to neutrality, higher WN scenarios could be aspired 

to by further developing policies and partnership working to deliver greater efficiencies, 

In order to meet the low WN scenario, the following measures are suggested to support its 

delivery. 

Delivery Requirements – Policy 

In order to meet the water neutrality target scenario given above, the following planning policy 

is recommended: 

POLICY RECOMMENDATION 1: 

Ensure all housing is water efficient, new housing development must go beyond Building 

Regulations and as a minimum reach Code for Sustainable Homes Level 1/2. 

Developers should prove that code levels 1 or 2 for water have been met. When considering 

planning applications for new development (regardless of size), the planning authority and all 

consultees should consider whether the proposed design of the development has incorporated 

water efficiency measures, including (but not necessarily limited to) garden water butts, low 

flush toilets, low volume baths, aerated spray taps, and water efficient appliances sufficient to 

meet 105l/h/d. 

In addition, it is recommended that the following policies be introduced, to assist with the 

implementation of the above planning policy: 


Carry out a programme of retrofitting and water audits of existing dwellings and non 

domestic buildings. Aim to move towards delivery of 10% of the existing housing stock 

with easy fit water savings devices 

This recommendation must work in parallel with the promotion and education programme 

outlined by Policy Recommendation 3. Further recommendations on how to achieve it are 

included in section 4.4.8 below, including recommended funding mechanisms.


4.4.8 Delivery Requirements – Partnership approaches 

To support Policy recommendation 2 


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Establish a programme of water efficiency promotion and consumer education, with the 

aim of behavioural change with regards to water use. 

Local authority owned housing should be targeted for a programme of retrofitting water efficient 

devices, to showcase the policy and promote the benefits. This should be a collaborative 

scheme between the Council, AWS and Waterwise. In addition, RWH/GWR schemes could be 

implemented into larger council owned and maintained buildings, such as schools or 

community centres. RWH could be introduced to public toilets, as has been carried out in 

Cambridge. 

The retrofitting scheme should then be extended to non-Council owned properties, via the 

promotion and education programme outlined by Policy Recommendation 3. 

A programme of water audits should be carried out in existing domestic and non-domestic 

buildings, again showcased by Council owned properties, to establish water usage and to 

make recommendations for improving water efficiency measures. The water audits should be 

followed up by retrofitting water efficient measures in these buildings, as discussed above. In 

private non-domestic buildings water audits and retrofitting should be funded by the asset 

owner, the cost of this could be offset by the financial savings resulting from the implementation 

of water efficient measures. Funding options for domestic properties are discussed above. 

AWS should consider a policy of moving towards 100% meter installation in the WRZs within 

the next update to the WRMP (2015). 

To support Policy recommendation 3 

In order to ensure the uptake of retrofitting water efficient devices for non-council properties, 

the Council should implement an awareness and education campaign, which could include the 

following: 

• working with AWS to help with its water efficiency initiative, which has seen over 20,000 

leaflets distributed directly to customers and at events across the region each year 91 ; 

• a media campaign, with adverts/articles in local papers and features on a local news 

programme; 

• a media campaign could be supplemented by promotional material, ranging from those that 

directly affect water use e.g. free cistern displacement devices, to products which will raise 

awareness e.g. fridge magnets with a water saving message; 

• encouraging developers to provide new residents with ‘welcome packs’, explaining the 

importance of water efficiency and the steps that they can take to reduce water use; 

• working with retailers to promote water efficient products, possibly with financial incentives 

as were undertaken as part of the Preston Water Initiative 92 ; 

91 Anglian Water Services, Water Resource Management Plan, 2010, http://www.anglianwater.co.uk/environment/water- 

resources/resource-management/


Sept 2011 

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• carrying out educational visits to schools and colleges, to raise awareness of water 

efficiency amongst children and young adults; 

• working with neighbourhood trusts, community groups and local interest groups to raise 

awareness of water efficiency; and 

• carrying out home visits to householders to explain the benefits of saving water, this may 

not be possible for the general population of East Cambridgeshire District, but rather should 

be used to support a targeted scheme aimed at a specific residential group, as was carried 

out for the Preston Water Initiative 93 . 

Responsibility 

The three policy recommendations above are targeted at the Council and AWS, as these are 

the major stakeholders, although the Environment Agency and other statutory consultees can 

also influence future development to ensure the water neutrality target of 24 percent is 

achieved. 

It is therefore suggested that responsibility for implementing water efficiency policies be shared 

as follows: 

• responsibility for ensuring planning applications are compliant with the recommended 

policies lies with the Council and Environment Agency (and other statutory consultees as 

appropriate); 

• responsibility for fitting water efficient devices in accordance with the policy lies with the 

developer, but this should be guided and if necessary enforced by the Council through the 

planning application process (as above); 

• responsibility to ensure continuing increases in the level of water meter penetration lies with 

AWS; 

• responsibility for retrofitting devices lies solely with the Council for Council owned housing 

stock and with the Council and developers (via section 106 agreements and CIL) for 

privately owned housing stock; 

• responsibility for promoting water audits lies with the Council. It is suggested that the 

Council sets targets for the numbers of businesses that have water audits carried out and 

that a specific individual or team within the Council is responsible for promoting and water 

audits and ensuring the targets are met. The same team or individual could also be act as a 

community liaison for households (council and privately owned) and businesses where 

water efficient devices are to be retrofitted, to ensure the occupants of the affected 

properties understand the need and mechanisms for water efficiency; and 

• responsibility for education and awareness of water efficiency should be shared between 

the Council, AWS and energy companies, as a partnership managed by the Council. 

However it should be noted that a major aim of the education and awareness programme, as 

outlined by Policy Recommendation 2, is to change peoples’ attitude to water use and water 

saving and to make the general population understand that it is everybody’s responsibility to 

reduce water use. Studies have shown that the water efficiencies in existing housing stock 

achieved by behavioural changes, such as turning off the tap while brushing teeth or reducing 

shower time, can be as important as the installation of water efficient devices. 

92 Preston Water Efficiency Report, Waterwise, March 2009, www.waterwise.org.uk 

93 Preston Water Efficiency Report, Waterwise, March 2009, www.waterwise.org.uk

Retrofitting funding options 


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In addition to possible resistance from existing householders, the biggest obstacle to retrofitting 

is the funding mechanism. 

Water companies are embarking on retrofit as part of their response to meeting Ofwat’s 

mandatory water efficiency targets. These programmes are funded out of operational 

expenditure. If a company has, or is forecasting, a supply-demand deficit over the planning 

period, water efficiency programmes can form part of a preferred option(s) set to overcome the 

deficit. However, these options are identified as part of the companies water resource 

management plans and will have to undergo a cost-benefit analysis. 

The Council could consider developer contributions to the Community Infrastructure Levy (CIL) 

or through S106 agreements. 

Part 11 of the Planning Act 2008 94 (c. 29) (“the Act”) provides for the imposition of a charge to 

be known as Community Infrastructure Levy (CIL). This is a new local levy that authorities can 

choose to introduce to help fund infrastructure in their area. CIL will help pay for the 

infrastructure required to serve new development, and although CIL should not be used to 

remedy pre-existing deficiencies, if the new development makes the deficiency more severe 

(as is the case with water resources in the East Cambridgeshire area) then the use of CIL is 

appropriate. 

Section 106 (S106) of the Town and Country Planning Act 1990 95 allows a local planning 

authority (LPA) to enter into a legally-binding agreement or planning obligation with a 

landowner in association with the granting of planning permission, known as a Section 106 

Agreement. These agreements are a way of delivering or addressing matters that are 

necessary to make a development acceptable in planning terms. They are increasingly used to 

support the provision of services and infrastructure, such as highways, recreational facilities, 

education, health and affordable housing. 

However, there are considerable existing demands on developer contributions and it is unlikely 

that all of the retrofitting required in East Cambridgeshire could be funded through these 

mechanisms; the Council therefore needs to look beyond developer contributions, possibly to 

the water companies, for further funding sources. Some councils offer council tax rebates to 

residents who install energy efficient measures (rebates jointly funded by council and Energy 

Company) 96 . ECDC should consider a similar scheme, although this would require the 

agreement of AWS. 

There are two possible European funding mechanisms available for the promotion of water 

efficiencies: 

• European Investment Bank (EIB); and 

• European Regional Development Funds. 

The EIB’s lending policy 97 sets out how the EIB will support water efficiency measures by water 

service providers and grant loans to promote water efficiency in buildings. This could be a 

possible funding route for a widespread retrofitting programme. 

European Regional Development Funds are more limited, as funds are often preferentially 

directed towards energy efficiency projects, with the aim of reducing carbon emissions to 

94 http://www.legislation.gov.uk/ukpga/2008/29/contents 

95 http://www.legislation.gov.uk/ukpga/1990/8/contents 

96 Cambridge (and surrounding major growth areas) WCS Phase 2, Halcrow, 2010 

97 http://www.eib.org/attachments/strategies/water_sector_lending_policy_2008_en.pdf


Sept 2011 

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achieve European targets. Allocated funding for the current programming period (2007 to 2013 

are mainly allocated to such projects 98 , although the possibility is funding for water efficiency 

project post-2013 should be investigated. 

Retrofitting monitoring 

During delivery stage, it will be important to ensure sufficient monitoring is in place to track the 

effects of retrofitting on reducing demand form existing housing stock. The latest research 

shows that retrofitting can have a significant beneficial effect and can be a cost effective way of 

managing the water supply-demand balance 99 . However, it is acknowledged that savings from 

retrofitting measures do diminish with time. This means that a long-term communication 

strategy is also needed to accompany any retrofit programme taken forward and this needs to 

be supported by monitoring so that messages can be targeted and water savings maintained in 

the longer-term. The communication and monitoring message also applies to new builds to 

maintain continued use of water efficient fixtures and fittings. 

4.5 Water Supply and Climate Change Adaptation 

Table 4-15 provides a summary of the potential climate change adaptation and mitigation 

measures that could be considered in the East Cambridgeshire District with regards to water 

resources and water supply infrastructure. The organisations likely to be responsible for leading 

these measures have been identified alongside the suggested timescale for these actions to 

start being taken forward (Immediate, Medium (1 - 10 years) and Long (10+ years). 

98 Ensuring Water for All, Scoping Study Final Report, Environment Agency, 2010 

99 Waterwise (2011): Evidence base for large-scale water efficiency, Phase II Final report

Potential 

Climate 

Change 

Temperature rise 

Winter rainfall increase 

Summer rainfall decrease 

Sea level rise 

Increase in weather extremes 

(heatwaves, intense rainfall, storms) 


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Table 4-15: Water Resources Potential Climate Change Adaptation and Mitigation Measures 100 

Potential Impact Adaptation and Mitigation Measures 

• Increase in demand for water 

in summer 

• Increased evapotranspiration 

• Increased peak demand 

• Faster water supply asset 

deterioration 

• Changes in process 

efficiency 

• Opportunity for more water 

storage 

• Inadequate pump capacity 

for raw water 

• Increased diffuse pollution 

• More frequent low river flows 

• Increased competition for 

water 

• Increased peak demand 

• Changing customer 

expectations 

• Saline intrusion 

• Asset loss 

• Increased run-off reduces 

recharge of aquifers 

• Decrease in raw water 

quality – increased treatment 

cost 

• Increased flooding and risk 

of service loss 

• Increased flooding and risk 

of service loss 

• Increased subsidence – pipe 

failure 

• Increased contamination 

• Peak demand delivery during 

heat waves 

• Ensure regional drought plans take into 

account the impacts of climate change 

• Manage seasonal changes in climate by 

reducing summer peaks in demand for 

water 

• Contribute to managing water demand 

through increased water efficiency in 

homes, businesses, industry and 

agriculture and promotion of water 

efficiency measures 


increasing winter storage 

• Endure adequate pump capacity for 

increased winter storage requirements 


runoff through SuDS, particularly for 

new / redevelopment close to river and 

water bodies 


reducing summer peaks in demand for 

water 

• Contribute to managing water demand 

through increased water efficiency in 

homes, businesses, industry and 

agriculture and promotion of water 

efficiency measures 

• Ensure that water abstraction is 

sustainable through monitoring 

• Ensure that water quality is suitable for 

abstraction through monitoring 

• Ensure that key assets are located 

inland and are not susceptible to being 

lost through sea level rise 

• Improve resilience of key water supply 

assets such as pumps, including new 

industry design standards for water 

assets 


runoff through SuDS, particularly for 

new / redevelopment close to river and 

water bodies 

• Improve RBMP Programme of 

Measures to ensure WFD objectives are 

met and include climate change 

allowance 

Lead Organisation(s) 

ECDC EA AWS NE 

Timescale 

for Action 

Medium 

Medium 

Immediate 

Medium 

Medium 

Immediate 

Medium 

Immediate 

Medium 

Medium 

Long 

Medium 

Immediate 

Medium

5 Surface Water Management 

5.1 The Vision 


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Surface water drainage methods that take account of run-off rates, water quality, pollution 

control, biodiversity and amenity issues are collectively referred to as Sustainable Drainage 

Systems (SuDS). Sustainable surface water management takes account of long term 

environmental and social factors in designing a surface water drainage system that avoids the 

problems of flooding, pollution or damage to the environment that may occur with conventional 

surface water management systems. 

The vision for sustainable surface water management in the proposed development in East 

Cambridgeshire is based on the following key aims: 

• 100% separation of surface and foul water drainage; 

• linkage to green infrastructure giving multiple benefits to users and ecology; 

• linkage to water efficiency measures, including rainwater harvesting; and 

• linkage to the Cambridgeshire wide Surface Water Management Plan (SWMP). 

As with the Cambridge WCS 101 , the ultimate vision for the East Cambridgeshire WCS is to 

achieve 100% above ground drainage for all future developments, where feasible. In addition, 

above ground drainage should include environmental enhancement and should provide 

amenity, social and recreational value. 

In order to achieve this vision, it is the intention for new development that there be 100% 

separation of foul and surface water drainage. While it is recognised that this may not be 

possible for all new development, depending on individual site constraints, the aspiration is to 

achieve either 100% separation, or as close to 100% as possible. All foul sewage will drain to a 

WwTW. This could be either an Anglian Water owned and managed WwTW, or a purpose built 

WwTW, dependent on individual site conditions. 

5.2 Justification 

Conventional surface water drainage systems were designed to convey rainwater and surface 

water run-off away as quickly as possible. This helps to prevent flooding of the drained area, 

but may cause flooding of downstream areas as the run-off patterns become ‘flashier’, with 

high peak flows caused by increasing areas of impermeable surfacing connected to the surface 

water drainage system. SuDS seek to mimic natural drainage patterns; by holding surface 

water run-off close to its source, run-off can be controlled and peak flows reduced. 

In addition to the increased flood risk, conventional drainage systems can cause pollution of the 

receiving watercourses as impermeable surfaces accumulate pollutants such as hydrocarbons, 

tyre fragments and debris, detergents and grit and particulates. SuDS systems can be used to 

treat surface water run-off as they trap debris and allow for the natural degradation of 

pollutants. 

The main legislative driver for the use of SuDS is the Flood and Water Management Act, which 

implements Sir Michael Pitt’s recommendations 102 requiring urgent legislation, following his 

100 

Some inputs edited from AWS Strategic Direction Statement 2010 – 2035 http://www.anglianwater.co.uk/about-us/statutoryreports/strategic-direction/ 

101 


102 

http://webarchive.nationalarchives.gov.uk/20100807034701/http:/archive.cabinetoffice.gov.uk/pittreview/thepittreview.html


Sept 2011 

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review of the 2007 floods. The Act gives new responsibility to Cambridgeshire County Council 

as a Lead Local Flood Authority (LLFA), which gives the County Council powers to: 

• issue Local Flood Risk Management Strategies for surface water run-off, groundwater and 

non-main rivers; and 

• carry out works for the management of surface water run-off and groundwater 

In implementing an above-ground sustainable surface water management system, developers 

would achieve the following benefits compared to conventional surface water drainage 

systems: 

• reduced capital and operational costs (less ‘hard’ engineering and pumping required); 

• reduced carbon emissions (less ‘hard’ engineering and pumping required); 

• enhanced water quality and a reduction in polluted run-off; 

• opportunities to integrate surface water management into amenity areas and enhance 

biodiversity through development; 

• contribute to a ‘network of protected sites, nature reserves, greenspaces and greenways’ (as 

defined in Cambridgeshire Horizons Green Infrastructure Strategy), and; 

• they are considered ‘best practice’ as advocated by the CIRIA SuDS Manual 

In order to quantify the above benefits, a comparison will be made of the SuDS vision with the 

‘business as usual’ strategy. The ‘business as usual’ strategy can be considered to be where 

all sites are drained by a piped underground network that leads to a surface watercourse. See 

section 5.3.2 below for an explanation of greenfield conditions and how this is calculated. 

5.3 Options for Surface Water Management 

5.3.1 SuDS Hierarchy 

SuDS systems should be designed in accordance with the SuDS hierarchy, also known as the 

SuDS management train. This hierarchy gives the preference for SuDS systems that should be 

introduced and can be used in series to change and manage the flow characteristics of surface 

water catchments, similar to a natural catchment. 

Figure 5-1: The SuDS management train 103 

103 Source: SuDS management train – CIRIA -http://www.ciria.org.uk/suds/suds_management_train.htm, accessed July 2011


Sept 2011 

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Where underlying soils and geology will allow, infiltration SuDS systems will be used, such as 

permeable paving, soakaways, etc. Where infiltration is not possible, for example due to 

impermeable soils or a high water table, attenuation SuDS such as constructed wetlands, 

balancing ponds or detention ponds will be used. Use of such attenuation SuDS will allow for a 

linkage of SuDS with green and blue infrastructure, for example parks and amenity spaces and 

the water features within them. 

Section 4.4.4 of this report discussed water saving and efficiency measures that could be 

included within new developments to reduce the water demand and ease the pressure on the 

already stretched water resources in East Cambridgeshire. Integrated use of SuDS and water 

efficiency measures will ensure that the collection of rainwater allows for its sustainable re-use. 

5.3.2 Greenfield Runoff rates 

104 Version 3 

PPS25 and its Practice Guide require that proposed development does not result in an 

increase in surface water runoff. The Ely Group of Drainage Boards has also advised that for 

watercourses under their jurisdiction, there is no additional capacity in the system and run-off 

post development must be at existing Greenfield runoff rates (where a site is currently 

undeveloped). 

In order to ensure this, attenuation of runoff is required to manage surface water runoff 

generated during the 1% annual probability storm event, inclusive of climate change. 

In order to calculate the proposed approximate attenuation volumes, the Quick Storage 

Estimate function of the Microdrainage WinDes software suite has been utilised. The 

calculations have used the following assumptions: 

• rainfall values and hydrological inputs have been provided from the Catchment Descriptors 

obtained from the FEH CD-ROM 104 ; 

• greenfield runoff rates derived using the IoH124 method; 

• one development scenario for each development area has been assumed (80% 

impermeable) to provide assumed areas of impermeable surfacing;


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• a conservative infiltration rate of 0.001 m/hr has been used as a worst-case estimate of the 

infiltration at each proposed development site; and 

• in order to account for climate change, an increase of 30% has been applied to rainfall 

values. 

As per PPS25, proposed development should ensure runoff rates from the development are no 

greater than pre-development rates. In order to ensure a conservative estimation of attenuation 

rates, it is assumed that all development sites would be required to attenuate to greenfield 

runoff rates. In reality, some development areas, such as urban sites in Ely or Soham for 

example, are likely to be brownfield sites and therefore to meet the requirements of PPS25 

would be required to attenuate to brownfield rates of runoff. Such details would be calculated 

and agreed during the completion of site-specific FRAs. 

Relevant guidelines and Building Regulations (such as PPS25, its Practice Guide and Building 

Regulations, Part H) require that surface water is managed in a hierarchical approach, as 

described above in section 5.3.1. 

Therefore, suggestions will be made for potential methods of surface water attenuation and 

management, in line with the above hierarchy and the SuDS Management Train, as described 

in the CIRIA C695 document, the SuDS Manual. In addition, potential constraints to SuDS such 

as proximity to Environment Agency Source Protection Zones, at each development site will be 

highlighted. 

5.3.3 SuDS options 

Prevention 

Through good site design, the volume of runoff produced from a site can be minimised. Using 

permeable rather than impermeable surfacing e.g. gravel or brick rather than concrete 

driveways will allow rainwater to infiltrate into the ground. Roofs and other impermeable areas 

can be drained to adjacent lawns or landscaped areas. 

Filter strips and swales 

Filter strips and swales are vegetated surface features that drain water evenly off impermeable 

areas. Swales are long shallow channels whilst filter strips are gently sloping areas of ground. 

Both these types of devices slow and filter the flow to mimic natural drainage patterns. Plant 

growth in the swale/filter strip traps organic and mineral particles that are then incorporated into 

the soil, while the vegetation takes up any nutrients, thereby effectively removing pollution. 

Swales and filter strips are often integrated into the surrounding land use, for example public 

open space or road verges. 

Permeable surfaces and filter drains 

Filter drains and permeable surfaces store surface water below via a permeable surface, for 

example: 

• grass or reinforced grass if the area will be trafficked; 

• gravelled areas; 

• solid paving blocks with large vertical holes filled with soil or gravel; 

• solid paving blocks with gaps between the individual units; 

• porous paving blocks with a system of voids within the unit; and

• continuous surfaces with an inherent system of voids. 


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The volume of storage depends on the voids ratio of the permeable fill or sub-base, the plan 

area and depth. Water can drain from the devices by infiltration, an under-drain, or be pumped 

out to a watercourse. In some situations the water should not be stored for extended periods as 

it can affect the strength of the surrounding soil. 

Sediment is trapped by the permeable fill, which filters runoff and removes pollutants. Some 

treatment and degradation is also provided of other pollutants, such as oil. 

The design and appearance of the surfaces can be chosen to compliment the design of the 

proposed development and by their nature, filter drains and permeable surfaces ensure an 

efficient use of space. 

Infiltration devices 

Infiltration devices drain water directly into the ground, which mimics and enhances the natural 

drainage patterns of undeveloped land, by increasing enhancing the natural capacity of the 

ground to store and drain water. Examples include soakaways, infiltration trenches and 

infiltration basins as well as swales, filter drains and ponds. Infiltration devices may be used at 

source or the runoff can be conveyed in a pipe or swale to the infiltration area. 

The amount of water that can be disposed of by an infiltration device within a specified time 

depends mainly on the infiltration potential of the surrounding soil. Limitations occur where the 

soil is not very permeable, the water table is shallow or the groundwater under the site may be 

put at risk. 

Infiltration techniques also provide storage for runoff. In the case of soakaways and infiltration 

trenches, this storage is provided in an underground chamber, lined with a porous membrane 

and filled with coarse crushed rock. Infiltration basins store runoff by temporary and shallow 

ponding on the surface. 

Treatment is provided for runoff, depending on the size of the media and the length of the flow 

path through the system, which controls the time taken for the runoff to pass into the 

surrounding soil. Pre-treatment may be required before polluted runoff is allowed into an 

infiltration device. 

Infiltration systems are easy to integrate into a site. They are ideal for use as playing fields, 

recreational areas or public open space. Infiltration basins can be planted with trees, shrubs 

and other plants, improving their visual appearance and providing habitats for wildlife. They 

increase soil moisture content and help to recharge groundwater, thereby mitigating problems 

of low river flows. 

Basins and ponds 

Basins are areas for storage of surface runoff that are free from water under dry weather flow 

conditions, for example detention basins, lagoons, wetlands or attenuation ponds which contain 

water in dry weather but have additional spare capacity for more when it rains. 

The structures can be used in combination, including both a permanently wet area for wildlife or 

treatment of the runoff and an area that is usually dry to cater for flood attenuation. Basins and 

ponds tend to be found towards the end of the surface water management train, so are used if 

source control cannot be fully implemented, if soils types do not allow for infiltration, if extended 

treatment of the runoff is required or if they are required for wildlife or landscape reasons. 

Basins and ponds treat runoff and reduce pollution by:


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• settlement of solids in still water - having plants in the water enhances calm conditions and 

promotes settlement; 

• adsorption by aquatic vegetation or the soil; and 

• biological activity. 

Basins and wetlands offer many opportunities for the landscape designer. Basins should not be 

built on, but can be used for sports and recreation. Permanently wet ponds can be used to 

store water for reuse, and offer excellent opportunities for the provision of wildlife habitats. Both 

basins and ponds can be part of public open space. 

5.4 Development site requirements 

As discussed above, greenfield runoff rates and SuDS sizings have been calculated using an 

assumed worst-case infiltration rate. In addition, as the detailed site designs are not known, a 

figure of 80% impermeable surfacing has been assumed for each site. The SuDS sizings given 

below should therefore be considered to be indicative only and are likely to be over-sized. 

Infiltration testing must be carried out on a site-by-site basis to establish the precise volumes 

and types of SuDS required for each site. 

Table 5-1 below shows the indicative SuDS requirements for each of the proposed 

development sites, to meet the greenfield runoff rate for a 1-in-100 year rainfall event, with a 

30% allowance for increased storm intensity with climate change. 

5.5 Climate Change Analysis 

It is predicted that the effects of climate change will cause the weather in the UK to continue to 

get warmer. It is expected that summers will continue to get hotter and drier while winters will 

continue to get milder and wetter and sea levels will rise along much of the coastline 

As well as changes in average temperature and rainfall, there will be changes in climatic 

extremes. Some weather extremes (such as very hot days and intense downpours of rain) will 

become more common whereas others, such as snowfall, will become less common. 

UKCP09 105 has predicted a series of Greenhouse Gas (GHG) emissions scenarios (low, 

medium and high) which are run through global climate models to give changes in a number of 

climatic variables including rainfall, wind patterns, temperature and sea level rise. 

With regards to surface water management and SuDS, climate change could lead to the 

following effects: 

• increasing the build up of contaminants between rainfall, leading to more polluted runoff 

when rainfall does occur; and 

• increasing peak surface water flows, which could require SuDS sizes to be increased. 

105 http://www.ukcip.org.uk 

The estimated indicative SuDS sizings given above have been calculated using the 1-in-100 

year rainfall event, plus an increase to allow for the effects of climate change. According to the 

requirements of PPS25 and its Practice Guide, residential development has an assumed 

design life of 100 years and non-residential development has an assumed design life of 60 

years. Therefore, in order to account for climate change for the residential development, a 30% 

allowance has been made, in accordance with table B.2 of PPS25. 

The effects of climate change have therefore already been considered within the indicative 

SuDS sizings given above for each of the proposed development areas. In addition, as the


Sept 2011 

106 



assessment of the required sizes used the worse-case infiltration rate it is likely that the SuDS 

required given above in Table 5-1 are significantly oversized. However, when designing the 

detailed drainage strategy for each of the proposed development areas it is essential that the 

impacts of climate change be incorporated within the design. This includes both an increase in 

attenuation storage and infiltration volume and area, but also an allowance for increased flood 

levels in rivers and estuaries that will result from increased fluvial flows.

Table 5-1: Indicative storage volumes required for proposed development sites in East Cambridgeshire 

Site Reference Site Description Geology 


Sept 2011 

Total Site Area 

(Hectares) 

107 

Site Developed Area* 

(Ha) 

Existing Runoff 

(greenfield) (l/s) (1 in 

100) 

08/00907/FUM Land at Highfield Farm, Ely Road, Littleport Till 1.707 1.37 12.5 624 - 849 

Required Storage 

Volume (m3) (1 in 100 

+ 30% CC) 

05/00335/RMM Phase 3, land off Prickwillow Road, Ely Till 16.3 13.04 119.1 5,934 – 8,082 

02/00950/RMA Land at Highfield Farm, Ely Road, Littleport Till 26.7 21.36 195.1 9,693 – 13,238 

07/01097/RMM 

Land between Beech Court & Village College, Parsons Lane, 

Littleport 

Till 4.556 3.64 33.2 1,657 – 2,257 

07/00386/FUM Lion Mills, Mill Corner, Soham Clay 3.318 2.65 24.2 1,206 – 1,642 

08/00223/FUM Lion Mills, Mill Corner, Soham (modified application) Clay 3.318 2.65 24.2 1,206 – 1,642 

08/00867/FUM Keith Leonard House 32 Lode Close, Soham Clay 0.534 0.43 3.9 196 - 267 

Map 10.2 Land west of 93-135 Lynn Road, Ely Till 2.348 1.88 17.2 855 – 1,165 

Map 8.2 Lisle Lane, Ely Peat 2.855 2.28 20.8 1,038 – 1,413 

Map 8.3 Lisle Lane, Ely Peat 1.098 0.88 8 401 - 546 

Map 5.1 Paradise, Ely Peat/Till 0.972 0.78 7.1 355 - 484 

Map 3.5 Land rear of Fordham Road, Soham Sands & Gravels 2.745 2.20 20.1 1,001 – 1,363 

Map 3.9 Station Road, Soham Sands & Gravels 3.08 2.46 22.5 1,119 – 1,525 

Map 3.10 Brook Street, Soham Sands & Gravels 21.97 17.58 160.6 8,000 – 10,895 

Eastern Gateway Soham Sands & Gravels 33.78 27.02 246.8 12,261 – 16,746 

Map 4.3 Land North of Grange Lane, Littleport Till 2.131 1.70 15.5 774 – 1,054 

Map 4.6 Land South of the Paddocks, Littleport Till 2.119 1.70 15.5 774 – 1,054 

Map 5.2 Land East of Bell Road, Bottisham Chalk 1.637 1.31 12 596 - 811 

Map 6.3 Land North of Newmarket Road, Burwell Chalk 6.862 5.49 50.1 2,499 – 3,403 

North Ely 1 Ely Peat/Till/Clay 74.98 59.98 537 27,242 – 37,324 

North Ely 2 Ely Peat/Till/Clay 139.4 111.52 932.6 51,078 – 70,256 

10/00373/OUM Land north-west of Regal Drive, Soham Sands & Gravels 3.335 2.67 24.4 1,215 – 1,655 

*In the absence of detailed site layout design, this is assumed to be 80% of the total site area. 



5.5.1 Ecological opportunities 

Ely 


Sept 2011 

108 



Ely Country Park is identified in the Cambridgeshire GI Strategy as a major new green 

infrastructure site. There is also a major green infrastructure corridor (‘Cam Valley: Cambridge 

to Ely’) identified as running to the east of the city (encompassing the Country Park) and which 

is allocated for enhancement within the Strategy. The key ‘North Ely’ development location will 

be tied into the Country Park to its east and a potential Country Park extension to its north. 

Located within this transitional zone will be ‘used in connection with sustainable urban drainage 

(SUDS) with attenuation ponds creating new habitats’ 106 . The Riverside and Station Gateway 

development area to the east of Ely is also in continuity with the Country Park and river corridor 

and will include ‘green ‘wedges’ to provide transition from proposed Country Park’ which could 

also provide a SuDS capability. There is also a new green corridor (the Chatteris to Ely Green 

Corridor) proposed to the west of Ely but this doesn’t appear to be connected to any of the 

major development areas in the city. 

Soham 

Soham is identified as straddling an existing green corridor to be enhanced and a new green 

corridor to be created in addition to being a location for significant new green infrastructure to 

the east of the town. This would tie in with the ‘Eastern Gateway’ and ‘Brook Street’ 

development areas which both lie to the east of town, close to the green infrastructure. SuDS 

for these development areas could therefore tie in well to the green corridors. 

Littleport 

Littleport is identified as being immediately to the west of an existing green corridor to be 

enhanced. In the case of this town, the key development areas are not connected with the 

green corridor identified within the Green Infrastructure Strategy being on the opposite side of 

the town. However, there is potential for the enhancement of ecological value in this south-west 

area of the town through new SuDS opportunities linked to the new development which could 

provide habitat for Cambridgeshire BAP species and habitats such as grazing marsh, great 

crested newt or water vole. 

Bottisham 

Bottisham is not identified as being near any corridors or strategic greenspace identified within 

the Cambridgeshire Green Infrastructure Strategy, but the ‘land east of Bell Road’ development 

area has potential for the enhancement of ecological value in this south-west area of the village 

through new SuDS opportunities linked to the new development which could provide habitat for 

Cambridgeshire BAP species and habitats such as grazing marsh, great crested newt or water 

vole. 

Burwell 

Burwell is immediately to the east of a major green hub identified within the Cambridgeshire 

Green Infrastructure Strategy, namely the Wicken Fen Vision (discussed in more detail above). 

However, the key development area in Burwell is on the opposite side of the town and as such 

106 Ely Masterplan document 2010. http://www.eastcambs.gov.uk/planning/ely-masterplan-details


Sept 2011 

109 



there are few, if any, opportunities for SUDS features to contribute to the Wicken Fen Vision. 

However, there is potential for the enhancement of ecological value in this eastern area of the 

village through new SuDS opportunities linked to the new development which could provide 

habitat for Cambridgeshire BAP species and habitats such as grazing marsh, great crested 

newt or water vole. 

There are also wider opportunities for developments to assist with the delivery of WFD 

objectives that will improve the ecological status of rivers such as the installation of fish 

passages, improvement of floodplain connectivity, in-channel enhancements such as the 

creation of backwaters and berms and the installation of deflectors. These enhancements 

would also help to delivery the objectives of previously mentioned strategies, such as the Great 

Ouse Wetland Vision and the 50 Year Wetland Vision, in addition to the WFD. 

5.5.2 Potential SuDS at Soham 

Of the eight development sites outlined for Soham, five of them are shown to be located on 

sands and gravels, which are inherently more permeable. It is therefore likely that these would 

be suitable for the use of infiltration SuDS. 

Four of the development sites are indicated to lie on clay soils and hence may not be suitable 

for infiltration methods of surface water management. Therefore, it is likely that surface water 

management at the Soham sites would utilise source control methods such as green roofs, 

storage via permeable paving reservoirs or on-site storage such as retention basins or ponds. 

Should site investigations indicate that soils at Soham are more permeable than indicated in 

Table 5-1 then infiltration methods should be investigated. 

Soham Lode is a Main River that flows through the centre of Soham and is within close 

proximity to the development sites known as Lions Mills, Keith Leonard House and Brook 

Street. The Lion Mills and Keith Leonard House development sites have been identified likely 

not to be suitable for infiltration methods of surface water management but following source 

control techniques could potentially discharge to the Soham Lode at greenfield runoff rates 

(with agreement with the Environment Agency). 

The remaining development sites appear to be hydraulically linked to the Soham Lode via 

County Council drains 107 . If, following infiltration testing infiltration SuDs are found not to be a 

feasible source control a combination of methods could be used to attenuate to these drains at 

greenfield runoff rates. 

Table 5-2: Summary of potential discharge points in for development sites in Soham if 

infiltration SuDS are not feasible 

Site 

Lion Mills, Mill Corner, 

Soham 

Keith Leonard House, 

Soham 

Potential receiving 

drain 

Soham Lode Not within an IDB 

boundary 

Soham Lode Not within an IDB 

boundary 

Relevant IDB Comment 

Soham Lode is immediately 

adjacent to development 

boundary. Surface water sewers 

are connected to the site. 

107 Further discussion is required with the SuDS Approval Body (SAB) and Highways Agency to utilise existing drains for disposal

Site 


Sept 2011 


drain 

Station Road, Soham Soham Lode via CC 

ditches 

110 


Not within an IDB 

boundary 

Brook Street, Soham Soham Lode Not within an IDB 

boundary 

Eastern Gateway, 

Soham 

Land northwest of 

Regal Drive, Soham 

Land rear of Fordham 

Road, Soham 

CC ditches running 

through the site. 

CC drain adjacent to 

Cherrytree Lane 

CC drain adjacent to 

Cherrytree Lane 

5.5.3 Potential SuDS at Ely 



The ditches on the site are likely 

to be connected to Soham Lode 

under the railway line. 

Soham Lode flows through the 

development site 

Middle Fen & Mere Not identified as IDB ditches but 

they are within the Middle Fen & 

Mere IDB boundary. An 

alternative could be East Fen 

Main Drain. 


boundary 


boundary 

A foul sewer runs along Fordham 

Road 

A foul sewer runs along Fordham 

Road 

In general, the soils and geology in and around Ely are believed to comprise peat and till. It is 

therefore unlikely that infiltration techniques such as soakaways, infiltration trenches, filter 

drains or swales may be suitable on any significant scale, although consideration should be 

given to combining infiltration techniques with large storage features such as retention basins. 

However, due to the land take required, these may not be as applicable for the smaller sites 

such as some of those proposed in Ely. 

It is likely that the peat soils found in and around Ely are naturally wet which could reduce the 

potential for infiltration SuDS techniques. If this is the case then other source control methods 

could be investigated such as storage via permeable paving, reservoirs, green roofs or water 

recycling. 

The Ely Ouse is a Main River that flows to the southeast of Ely that appears to be hydraulically 

linked via CC drains to the two potential development sites around Lisle Lane. As individually 

these development sites are small attenuation SuDS could be applied to serve both of these 

and possibly the Paradise Centre. The land to the east of Ely has been identified to be Ely 

Country Park as part of the Cambridge Green Infrastructure Strategy, which could incorporate 

a strategic attenuation pond to serve the Lisle Lane development sites. 

The majority of the development for Ely is proposed development is to the north of the city. 

These sites are larger and large storage features are more likely to be achievable on these 

developments. There are existing County Council drains 107 running through or close to these 

developments sites which, following attenuation could be discharged to. Additionally, the OS 

mapping shows there is an existing reservoir located in the middle of the development site on 

the east of Lynn Road. This reservoir appears to be connected to the development around Ely 

Hospital by a surface water sewer. The capacity of this existing reservoir and connection could 

potentially be increased to accommodate some of the proposed development. 

Table 5-3: Summary of potential discharge points in for development sites in Ely if 


Site 


drain 

Relevant IDB Comment

Site 

Land west of 93-135 

Lynn Road, Ely 


Sept 2011 


drain 

CC ditch drains to the 

north 

Paradise Centre, Ely Great Ouse via CC 

ditch 

Lisle Lane, Ely (1 of 2) Great Ouse via CC 

ditch 

Lisle Lane, Ely (2 of 2) Great Ouse via CC 

ditch 

North Ely (1 of 2) CC ditches running 

through the site 

North Ely (2 of 2) CC ditches running 

through the site 

111 



boundary 


boundary 


boundary 


boundary 


boundary 


boundary 



A surface water sewer runs along 

Lynn Road. 

A foul sewer runs through the 

site. Potential for strategic SuDS 

attenuation pond as part of Ely 

Country Park. 

Potential for strategic SuDS 


Country Park. 

Potential for strategic SuDS 


Country Park. 

A surface water sewer runs 

through the site that appears to 

connect the development 

surrounding the Hospital to a 

reservoir – the capacity of this 

infrastructure could be increased. 

A Cambridgeshire-wide SWMP was commissioned by Cambridge City and Cambridge County 

Council has been prepared by Edenvale Young and Hyder Consulting 108 . The SWMP has 

modelled surface water flows and flooding throughout Cambridgeshire. The findings of the 

SWMP should be taken into consideration when designing SuDS for individual developments, 

to ensure there is a strategy developed to manage surface water flows coming onto the site 

from surrounding land. The SuDS design for individual sites will manage surface water run-off 

within the development sites and from the development site to other areas. 

In particular, the SWMP identified ‘wetspots’ within the County through a review of the historical 

flooding database, the Environment Agency’s National Receptor Database (NRD) and the 

Flood Maps for Surface Water (FMfSW). A total of 273 wetspots were identified which were 

then given a Multi-Criteria Analysis (MCA) score based on their potential flood risk and the 

likely damages to people, properties, infrastructure and the environment as a result of surface 

water flooding. The top ten wetspots (those with the highest MCA score) were identified for a 

more detailed assessment and optioneering. Within the East Cambridgeshire District, Ely was 

chosen in the top ten. 

5.5.4 Potential SuDS at Littleport 

The soils around Littleport are indicated to comprise of Till and it is therefore likely that 

infiltration methods of surface water management may not be suitable. Consideration should 

either be given to source control methods such as green roofs or a combination of infiltration 

techniques with large storage features such as retention basins. 

All of the development sites proposed for Littleport are to the west of the town. The natural 

topography lends itself to these sites being drained into the Wood Fen Catchwater that is in the 

jurisdiction of the Littleport & Downham IDB. As the majority of these sites are presently 

108 Edevale Young & Hyder Consulting (2011) Cambridgeshire Surface Water Management Plan.


Sept 2011 

112 



Greenfield attenuation to greenfield runoff rates would need to be achieved on site prior to 

discharging into the Wood Fen Catchwater. The Land at Highfield Farm has an existing 

surface water sewer that appears to be connected to the Wood Fen Catchwater, which could 

be utilised, depending on its current and future load. The IDB will need to be consulted before 

any connections are made. 

For the Land north of Grange Lane development an alternative discharge could be made into 

the Padnal Catachwater that is under the jurisdiction of Padnal & Waterden IDB. 

Table 5-4: Summary of potential discharge points in for development sites in Littleport if 


Site 

Land at Highfield 

Farm, Ely Road, 

Littleport 

Residue at Highfield 

Farm, Ely Road, 

Littleport 

Land at Parsons Lane, 

Littleport 

Site at Highfield Farm, 

Ely Road, Littleport 

Land north of Grange 

Lane, Littleport 

Land south of the 

Paddocks, Littleport 


drain 

5.5.5 Potential SuDS at Bottisham 

Wood Fen Catchwater Littleport & Downham 

Internal Drainage 

Board 



Board 



Board 



Board 



Board 



Board 


A surface water sewer runs 

through the site that may connect 

to the Wood Fen catchwater. 

There is a closer ditch along 

Grange Lane that would be the 

feeder. An alternative could be 

Padnal Catchwater. 

The soils around Bottisham are believed to be chalk, which is likely to be suitable for the use of 

infiltration SuDS. It should be noted that the calculation of required storage and attenuation 

volumes given above in Table 5-1 are based on worse-case infiltration values. Infiltration rates 

for chalk are likely to be higher than those used for these indicative SuDS sizings. As with all 

the sites, site specific infiltration testing should be carried out to inform the detailed design of 

site drainage and SuDS requirements. 

The proposed development site at Bottisham is relatively small at just 1.6 hectares and it is 

therefore possible that a combination of source control measures (e.g. green roofs) and 

infiltration techniques such as swales or permeable surfacing may be sufficient for this 

proposed development area. 

There are no groundwater source protection zones (SPZs) in the vicinity of the proposed 

development site which would prohibit the use of infiltration SuDS, but should there be 

insufficient area on site for infiltration SuDS to drain the entire development, or should 

infiltration rates prove unfavourable when infiltration testing is carried out, there is a


Sept 2011 

113 



watercourse immediately adjacent to the proposed development site at Land east of Bell Road. 

This watercourse would provide a natural connection and outfall for an attenuation SuDS 

device such as a detention basin or balancing pond. 

Table 5-5: Summary of potential discharge points in for development sites in Bottisham 

if infiltration SuDS are not feasible 

Site 

Land east of Bell 

Road, Bottisham 


drain 

CC drain along 

northern boundary of 

the site. Or, Bottisham 

Drain 

5.5.6 Potential SuDS at Burwell 


Swaffham CC Drain is not identified as IDB 

drain but it is within the boundary. 

Bottisham Drain is a Swaffham 

IDB drain. 

As with the potential development site in Bottisham, the soils around Burwell are believed to be 

chalk, which is likely to be suitable for the use of infiltration SuDS. It should be noted that the 

calculation of required storage and attenuation volumes given above in Table 5-1 are based on 

worse-case infiltration values. Infiltration rates for chalk are likely to be higher than those used 

for these indicative SuDS sizings. As with all the sites, site specific infiltration testing should be 

carried out to inform the detailed design of site drainage and SuDS requirements. 

The proposed development site at Burwell is just under 7 hectares; assuming the proposed 

development will have 80% impermeable surfacing this would give 5.49 hectares of 

hardstanding from which surface water run-off would need to be sustainably disposed. It is 

therefore possible that infiltration devices alone may not be sufficient for this site (depending on 

infiltration rates) and therefore a combination of infiltration techniques and attenuation 

measures may be required. Source control techniques such as green roofs should also be 

incorporated into site design. 

However, there are no large drains in the vicinity of the proposed development site and the 

smaller ditches may not have sufficient capacity to provide an outflow point from an attenuation 

pond. In addition to the infiltration assessment required for the detailed site design of the 

proposed development, an assessment of the channel capacity of the ditches adjacent to the 

land north of Newmarket Road site should be carried out. 

Should infiltration rates and channel capacity prove to both be insufficient for the 5.49 hectares 

which require drainage, connection to the existing surface water sewer system could be 

investigated. 

Table 5-6: Summary of potential discharge points in for development sites in Burwell if 


Site 

Land north of 

Newmarket Road, 

Burwell 


drain 


- No drains seem obvious 

discharge points

5.5.7 SuDS and groundwater protection 


Sept 2011 

114 



When considering infiltration SuDS, developers should consider the following with respect to 

protection of water quality in aquifers in the study area: 

• the water environment is potentially vulnerable (for several of the growth area zones) and 

there is an increased potential for pollution from inappropriately located and/or designed 

infiltration SuDS; 

• soakaways and other infiltration SuDS must not be constructed in contaminated ground. 

The use of infiltration drainage would only be acceptable if a phased site investigation (in line 

with CLR11, ‘Model Procedures for the Management of Land Contamination’) showed the 

presence of no significant contamination. The use of non infiltration SUDS may be 

acceptable subject to agreement with the Environment Agency. 

• the maximum acceptable depth for infiltration SUDS is 2m below ground level, with a 

minimum of 1.23m clearance between the base of the infiltration SUDS and peak seasonal 

groundwater levels; this is particularly important in the study area with the large number of 

field drains suggesting shallow groundwater. The Environment Agency considers that deep 

boreholes and other deep soakaways systems are not appropriate in areas where 

groundwater constitutes a significant resource. Deep soakways increase the risk of 

groundwater pollution; and 

• use of infiltration drainage methods will depend on local groundwater level. As well as the 

predominant geology. 

5.6 Financial cost of SuDS 

The costs provided for each site, as shown below in Table 5-7, should also be considered to be 

indicative and should be used to provide a point of comparison only, rather than as an 

indication of the actual cost of SuDS implementation. 

Costs for SuDS have been taken from the generic construction costing table of the CIRIA 

publications ‘The SuDS manual – C697 109 ’. This publication gives an indicative cost of £20 per 

m 3 . Costs for SuDS have been based purely on surface attenuation costs to provide the 

required runoff rate restriction. It does not include costs for infiltration devices as the extent to 

which infiltration will be feasible is not known at this strategic level of planning. 

Table 5-7: Indicative SuDS costs 

Site Description 


(Ha) 

Indicative cost of required 

storage volume** (£) 

Land at Highfield Farm, Ely Road, 

Littleport 1.37 12,480-16,980 

Phase 3, land off Prickwillow Road, Ely 13.04 118,680-161,640 


Littleport 21.36 193,860-264,790 

Land between Beech Court & Village 

College, Parsons Lane, Littleport 3.64 33,140-45,140 

Lion Mills, Mill Corner, Soham 2.65 24,120-32,840 

Lion Mills, Mill Corner, Soham (modified 

application) 2.65 24,120-32,840 

Keith Leonard House 32 Lode Close, 

Soham 0.43 3,920-5,340 

109 CIRIA (2007) – The SuDS manual (C697)


Sept 2011 

115 



Site Description 


(Ha) 

Indicative cost of required 

storage volume** (£) 

Land west of 93-135 Lynn Road, Ely 1.88 17,100-23,300 

Lisle Lane, Ely 2.28 20,760-28,260 

Lisle Lane, Ely 0.88 8,020-10,920 

Paradise, Ely 0.78 7,100-9,680 

Land rear of Fordham Road, Soham 2.20 20,020-27,260 

Station Road, Soham 2.46 22,380-30,500 

Brook Street, Soham 17.58 160,000-217,900 

Soham 27.02 245,220-334,920 

Land North of Grange Lane, Littleport 1.70 15,480-21,080 

Land South of the Paddocks, Littleport 1.70 15,480-21,080 

Land East of Bell Road, Bottisham 1.31 11,920-16,220 

Land North of Newmarket Road, Burwell 5.49 49,980-68,060 

Ely 59.98 544,840-746,480 

Ely 111.52 1,021,560-1,405,120 

Land north-west of Regal Drive, Soham 2.67 24,300-33,100 

*In the absence of detailed site layout design, this is assumed to be 80% of the total site area. 

** Assumed to be £20 per m3 

5.7 Best Practice Examples 

5.7.1 Lamb Drove 

Lamb Drove 110 is a residential development to the west of Cambridge, in the town of 

Cambourne. It is a one hectare site of 35 affordable homes built by Cambridge Housing Society 

in 2004-2006. The site was chosen to show case innovative SuDS Sustainable Water 

Management Techniques. The project was commended in the 2006 RTPI National Planning 

Awards, and subsequent Monitoring Project (2008 – 2010). 

A range of SuDS measures were used in the Lamb Drove development, including 

• water butts are provided for houses to collect roof water; 

• permeable paving - the paving within the adoptable roads and in some of the car parking 

areas is of permeable construction; 

• a green roof - a small demonstration green sedum roof was included to reduce and treat 

runoff; 

• swales - excess water from the site is fed into a series of shallow open channels, further 

slowing the flow of water and continuing the water treatment process; 

• detention and wetland basins - sculpted depressions in open spaces help to slow down the 

runoff rate and store water on a temporary short-term basis during extreme events; and 

• a retention pond – attenuates surface water runoff from the development. 

The Lamb Drove development uses the principles of the SuDS management train, as 

discussed above in section 5.3.1, to control the runoff starting as close as possible to its 

source. The use of source control features (water butts, permeable paving etc) within the 

housing development areas manages most pollution and deals with the day-to-day runoff 

storage requirements. 

110 http://www.ciria.org.uk/suds/cs_lamb_drove.htm


Sept 2011 

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When the capacity of source control measures are exceeded the excess water is safely stored 

and treated in larger SuDS features integrated within public open space until the flood threat 

has passed. Such measures also contribute to the provision of green space, visual amenity and 

promoting wildlife. 

5.7.2 Dunfermline Eastern Expansion 

The Dunfermline Eastern Expansion 111 (DEX) is a 550ha site to the east of Dunfermline in 

Scotland. The site, which was predominantly green field, will be developed over the next 20 

years as a mixture of industrial, commercial, residential and recreational areas. The site lies 

over largely impermeable geology and infiltration SuDS and the downstream catchment is 

known to suffer from existing flooding issues. An overall site-wide SuDS design was therefore 

essential. 

The watersheds were divided into a number of sub-catchments connecting into a spinal SuDS 

network of retention basins, swales, regional extended detention ponds and wetlands. Much of 

the spine road system is drained using offlet kerbs, filter drains and swales, which discharge 

into extended detention basins and wetlands which also serve adjoining housing areas. 

Treatment of surface water run-off from the development and roads is achieved through a 

system of regional ponds and wetlands prior to discharge to the watercourses. Ponds and 

basins are widely used to achieve maximum attenuation of storm flows. 

5.7.3 Cambourne Pool and Redruth redevelopment 

As part of the urban regeneration of Cambourne, Pool and Redruth 112 , a SuDS network has 

been incorporated as a blue corridor with paths for cyclists and pedestrians adjacent to the 

SuDS features. The design allows low flows to be accommodated within the SuDS channel, 

with an overflow for higher flows that exceed the channel capacity to spill over onto the cycle 

and footpaths. 

5.8 Adoption and maintenance of SuDS 

Under the Flood and Water Management Act, responsibility for the adoption and maintenance 

of SuDS systems has been clarified. Before the implementation of the Act, maintenance and 

responsibility for SuDS systems in developments was inconsistent with some SuDS systems 

becoming ineffective some time before their design life was exceeded due to inadequate 

maintenance. 

The Act will confirm the exact arrangement for adoption and maintenance of SuDS systems 

during 2012, but for the purposes of this Level 2 WCS it should be assumed that: 

• Cambridgeshire County Council will become responsible for the adoption and maintenance 

of new build SuDS; 

• Cambridgeshire County Council will become the SuDS approving body (SAB) for all new 

build SuDS; 

• the requirements for approving new build SuDS will be outlined in forthcoming national 

standards on the construction and operation of surface water drainage; and 

• the current right to connect new developments to the existing public surface water sewerage 

network will be revoked and new surface water drainage systems will need to be approved in 

111 http://www.ciria.org.uk/suds/cs_dunfermline_eastern_expansion.htm 

112 http://www.cprregeneration.co.uk


Sept 2011 

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line with forthcoming National Sustainable Drainage Standards (to be published in 2012 113 ) 

before any connection to the public sewerage network is allowed. 

5.8.1 Mitigation and Adaptation measures for new development 

In order to assess the measures that need to be taken for an individual development to adapt 

to climate change, the UKCP09 Adaptation Wizard 114 provides guidance on the factors that 

should be taken into consideration. The tool will help a developer assess vulnerability to current 

climate and future climate change, identify options to address key climate risks, and help to 

implement a climate change adaptation strategy. 

The first stage of this is to assess vulnerability, by identifying: 

• exposure to climate hazards; 

• sensitivity to climatic variability; and 

• the capacity to adapt. 

The developer should then conduct a qualitative risk assessment to identify high level climate 

risks, and compare the relative importance of these climate risks with other non-climate related 

risks. This will then identify the priority climate risks that require an adaptation response. 

Adaptation options can then be identified, along with a programme for action to implement the 

chosen adaptations. 

The timeline for climate change effects is difficult to predict, although the UKCP09 predictions 

have produced estimated timelines for the changes in precipitation for the 2020s, 2050s and 

2080s. Figure 5-2 below shows the change in summer and winter mean precipitation in the 

2080s under a High Emissions scenario (i.e. worst case scenario) for the East Cambridgeshire 

and Fenland Study Area. 

113 http://ww2.defra.gov.uk/news/2010/07/29/benyon-flood-speech/ 

114 http://www.ukcip.org.uk/wizard/


Sept 2011 

118 



Figure 5-2 Change in Summer and Winter Mean Precipitation for 2020s, 2050s and 2080s 

(High Emissions Scenario) – UKCIP02 and UKCP09 projections. Black vertical lines 

represent ‘Very Likely’ (10% to 90% probability) range for UKCP09 projections 

For new development, it is most likely that the requirements of PPS25 will ensure that climate 

change adaptation is taken into account when designing the surface water management 

system for the proposed development. As with the indicative SuDS sizings given above, all 

drainage design for new developments should include an allowance for climate change, in 

accordance with the requirements of PPS25 and any subsequent National Policy Statements.

5.9 Conclusions 


Sept 2011 

119 



Indicative SuDS sizes and costs for the proposed development sites have been provided above 

in sections 5.4 and 5.5. The assessment has identified the types of SuDS methods that are 

available to developers and the possible limitations on using these at the individual 

development sites. It has been shown from the case studies provided, that developing an 

overall SuDS strategy for development sites is essential, especially for the larger sites where 

the development is likely to be phased. The Case Study at Dunfermline demonstrates the 

effectiveness of site wide planning for large scale SuDS, which may also be applicable to the 

large Eastern Gateway site in Soham where large scale attenuation SuDS may be required. 

Further study will be needed on an individual site basis, to establish accurate infiltration rates to 

allow exact SuDS sizings to be incorporated into the detailed development design. 

5.10 Recommendations 

In order to support the surface water management strategy discussed in this section of the 

report, the following planning policies are recommended. 

Policy recommendation 1 

• In accordance with the Building regulations, developers should ensure foul and surface 

water from new development and redevelopment are kept separate where possible. 


• Developers should aspire to achieve 100% above ground drainage for all future 

developments, where feasible. Where this is not feasible due to for example housing 

densities, land take, ground conditions, topography, or other circumstances, the development 

proposals should maximise opportunities to use SuDS measures which require no additional 

land take, i.e. green roofs, permeable surfaces and water butts. 


• Developers should ensure linkage of SuDS to green infrastructure to provide environmental 

enhancement and amenity, social and recreational value. SuDS design should maximise 

opportunities to create amenity, enhance biodiversity, and contribute to a network of green 

(and blue) open space. 


• Developers should ensure linkage of SuDS to water efficiency measures, including rainwater 

harvesting. 


• Developers should ensure SuDS design supports the findings and recommendations of the 

Cambridgeshire wide Surface Water Management Plan (SWMP) and East Cambridgeshire 

SFRA. 


• Developers should ensure, where possible that SuDS are designed to deliver water quality 

improvements in the receiving watercourse or aquifer.


Sept 2011 

120 



6 Potential Growth Area Infrastructure requirements 

The section of the WCS report focuses on the key growth areas of East Cambridgeshire and 

provides a detailed breakdown of the infrastructure constraints and solutions at a settlement 

and site specific level. 

It includes an assessment of constraints and solutions on water supply, wastewater treatment, 

wastewater networks, and flood risk to specific sites (fluvial and tidal flooding), as well as the 

surface water management requirements of each site to assist with development of site specific 

policies, settlement area actions plans and specific developer guidance.

6.1 Ely Potential Development Areas 

Housing No. of 

dwellings 

Already built 

(net completions 

2001-10) 

Extant 

New Allocations 

Estimated Windfalls 

Total 

Housing to be 

Assessed ( =Total 

minus Already built) 

Employment 

2098 

215 

3382 

135 

5830 

3732 

jobs 

Proposed jobs 5711 

Land total 54.38 Ha 

Employment to be 

assessed 

6.1.1 KEY 

- watercourse 

- sewer 

- WwTW catchment boundary 

- housing site boundary 

- employment site boundary 

6.1.2 

6.1.3 

6.1.4 

6.1.5 

5711 


Sept 2011 

Location of Potential Development 

6.1.6 Water Cycle Constraints Assessment 

Water Cycle Area Summary Overall 

Assessment 

Water Resources 

and Water Supply 

(Town wide) 

• The Ely planning Zone has sufficient water for all growth under future 

average conditions and sufficient water for 90% of the growth under 

peak/dry conditions 

• However, this PZ has a predicted deficit after growth during average 

and peak demand conditions; therefore a new solution may be 

required by AWS through their WRMP by the end of the plan period if 

water efficiency measures do not restrict water use further 

121 




Assessment 

Flood Risk 

Lisle Lane site (1 of 

2) 

• Lisle Lane proposed site (area 1 of 2) is largely within FZ2 highly 

vulnerable development should be avoided in this area and 

development should be sequentially located in the North and West of 

the site which are in flood zone 1. 

All other sites • The majority of the remaining proposed development falls FZ1. 

SuDS and Surface 


Management 

Wastewater 

Treatment and 

water quality 

(Town wide) 

Ecology and 

Biodiversity 

6.1.7 SuDS requirements 

• It is likely that the peat soils found in and around Ely are naturally wet 

which could reduce the potential for infiltration SuDS techniques. If this 

is the case then other source control methods could be investigated 

such as storage via permeable paving, reservoirs, green roofs or water 

recycling. 

• The main river Ouse is located to the southeast of Ely, whereas the 

proposed development sites are to the north. However, there are 

smaller drains and streams near to the larger proposed development 

sites to the north of the town, which could allow for connection of the 

surface water drainage system, subject to IDB approval. This would be 

needed as the soils types identified at these sites are Peat/Till/Clay, 

which could have limited permeability for infiltration SuDS. 

• There is a potential for a Strategic SuDS solution as part of Ely 

Country Park that could serve the developments around Lisle Lane 

• The Ely WwTWs combined have sufficient capacity to accommodate 

all potential growth 

• A change in discharge consent is not be required for projected growth 

Constraint 

• No major constraints identified 

Opportunity 

• Ely Country Park is identified in the Cambridgeshire GI Strategy as a major new 

green infrastructure site. There is also a major green infrastructure corridor (‘Cam 

Valley: Cambridge to Ely’) identified as running to the east of the city 

(encompassing the Country Park) and which is allocated for enhancement within 

the Strategy. The key ‘North Ely’ development location will be tied into the Country 

Park to its east and a potential Country Park extension to its north. Located within 

this transitional zone will be ‘used in connection with sustainable urban drainage 

(SuDS) with attenuation ponds creating new habitats’115. The Riverside and 

Station Gateway development area to the east of Ely is also in continuity with the 

Country Park and river corridor and will include ‘green ‘wedges’ to provide transition 

from proposed Country Park’ which could also provide a SuDS capability. There is 

also a new green corridor (the Chatteris to Ely Green Corridor) proposed to the 

west of Ely but this doesn’t appear to be connected to any of the major 

development areas in the city. 

Site Total site area 

(Ha) 

Site developed 

area (Ha) 


Volume (m 3 ) (1 in 100 + 

30% CC) 

Phase 3, land off Prickwillow Road, Ely 1.707 1.37 624 - 849 

Land west of 93-135 Lynn Road, Ely 2.348 1.88 855 – 1,165 

115 Ely Masterplan document 2010. http://www.eastcambs.gov.uk/planning/ely-masterplan-details

Lisle Lane, Ely 2.855 2.28 1,038 – 1,413 

Lisle Lane, Ely 1.098 0.88 401 - 546 

Paradise, Ely 0.972 0.78 355 - 484 

North Ely (1) 74.98 59.98 27,242 – 37,324 

North Ely (2) 139.4 111.52 51,078 – 70,256 

6.1.8 Wastewater network constraints 

Site Summary Earliest 

date to 

connect 

Phase 3, land off The growth proposed at the site (140) is unlikely to 

Prickwillow Road, Ely 

Land west of 93-135 

Lynn Road, Ely 


Sept 2011 

cause significant capacity concerns 

The majority of the network on the connection route is 

likely to have sufficient capacity; however there are 

sewer flooding incidents downstream and hence 

connection could exacerbate this problem. A new 

solution is therefore likely to be required 

Lisle Lane, Ely Not assessed 

Lisle Lane, Ely The growth proposed at the site (185) is unlikely to 

cause significant capacity concerns 

Paradise, Ely The majority of the network on the connection route is 


sewer flooding incidents downstream and hence 

connection could exacerbate this problem. A new 

solution is therefore likely to be required 

North Ely (1) The majority of the network on the connection route is 

likely to have sufficient capacity; however significant 

growth is proposed and the capacity will need to be 


North Ely (2) The majority of the network on the connection route is 


sewer flooding incidents downstream, wastewater pipe 

sizes become restricted and hence connection could 

exacerbate this problem. A new solution is therefore 


6.1.9 Phasing Assessment 

Phase Dwellings Employment Infrastructure Constraints 

Baseline (2010) - - 

2010 – 2014 933 1428 

2015 - 2019 933 1428 

2020 - 2024 933 1428 


Resources 

and Water 

Supply 

2011 

2015 

2011 

2015 

2011 

2015 116 

Wastewater Treatment & water quality 

Pre-dev 

enquiry 

required? 

116 The area of Ely site 2 is currently in the Ely Old WwTW catchment. It is possible that connection to Ely New WwTW would be possible 

in tandem with North Ely site 1, which would be subject to a pre-dev enquiry 

122 

2025 - 2031 933 1428 

Total 3732 5711 



6.2 Soham Potential Development areas 


dwellin 

gs 

Already built 


2001-10) 

Currently Permitted 



Total 

Housing to be 

Assessed (=Total 


Employment 

Proposed jobs 



assessed 

698 

379 

1311 

240 

2628 

1930 

jobs 

1245 

1245 


Sept 2011 

Location of Development 



Assessment 



(Town wide) 

Flood Risk 

Brook St Site 

Station Road 

All Other sites 

• The Ely planning Zone covering Soham has sufficient water for all 

growth under future average conditions and sufficient water for 90% of 

the growth under peak/dry conditions 





• The Brook Street Development area spans over a stretch of the river 

which puts approximately 20% of the area in Flood Zone 3 and a small 

proportion in zone 2. An FRA for Brook Street has been completed by 

the landowners/developers, and indicates that mitigation works are 

entirely possible. The evidence was accepted by an Inspector to the 

Core Strategy, hence the site is included as a potential allocation with 

the caveat that mitigation is required. 

• Station road proposed area is likely to fall entirely within Flood Zone 3. 

Significant flood mitigation measures would be required. An FRA for 

Station road has been completed by the landowners/developers, and 

indicates that mitigation works are entirely possible. The evidence was 

accepted by an Inspector to the Core Strategy, hence the site is 

123 




Assessment 



Management 

Wastewater 

Treatment and 

Water Quality 

Ecology and 

Biodiversity 

included as potential allocation with the caveat that mitigation is 

required. 

• Other proposed sites fall within FZ1 with the exception of a small area 

in the South of the Eastern gateway area (approx 5%) 

• It is likely that surface water management at the Soham sites would 

need to utilise source control methods such as green roofs, storage via 

permeable paving reservoirs or on-site storage such as retention 

basins or ponds. 

• Given the site sizes and potential land take, the Brook Street and 

Eastern Gateway sites would be potentially more viable for surface 

storage such as wet ponds. 

• Should site investigations indicate that soils at Soham are more 

permeable than indicated in Table 5-1 then infiltration methods should 

be investigated? 

• If a discharge to a watercourse is necessary Soham Lode is a Main 

River that flows through the centre of Soham and is within close 

proximity to the development sites known as Lions Mills, Keith Leonard 

House and Brook Street. The remaining development sites appear to 

be hydraulically linked to the Soham Lode via County Council 

drains107. 

• An increase in flow consent would be required to accommodate any 

development as there is no further capacity. 

• To ensure no deterioration in downstream quality, process upgrades 

will be required to meet tighter BOD limits, this may restrict initial 

connections until AMP6 (2015 onwards) when the upgrades could be 

in place 

• Further P stripping may be required, but this is likely to be achievable 

within the limits of conventional treatment 

• Future Good status cannot be achieved without growth, hence growth 

should not be seen as a barrier to attaining future Good status under 

the WFD. 

Constraint 

• No major constraint identified 

6.2.2 SuDS Requirements 

Opportunity 

• Soham is identified as straddling an existing green corridor to be enhanced and a new 

green corridor to be created in addition to being a location for significant new green 

infrastructure to the east of the town. This would tie in with the ‘Eastern Gateway’ and 

‘Brook Street’ development areas which both lie to the east of town, close to the green 

infrastructure. SuDS for these development areas could therefore tie in well to the green 

corridors. 


(Ha) 


area (Ha) 


Volume (m 3 ) (1 in 100 + 

30% CC) 

Lion Mills, Mill Corner, Soham 3.318 2.65 1,206 – 1,642 

Keith Leonard House 32 Lode Close, 

Soham 

0.534 0.43 196 - 267

Land rear of Fordham Road, Soham 2.745 2.20 1,001 – 1,363 

Station Road, Soham 3.08 2.46 1,119 – 1,525 

Brook Street, Soham 21.97 17.58 8,000 – 10,895 

Soham (Eastern gateway) 33.78 27.02 12,261 – 16,746 

Land north-west of Regal Drive, 3.335 2.67 1,215 – 1,655 



date to 

Lion Mills, Mill Corner, 

Soham 

Keith Leonard House 32 

Lode Close, Soham 

Land rear of Fordham 

Road, Soham 

Station Road, Soham 


Sept 2011 

The majority of the network on the connection route is likely to 

have sufficient capacity; however the capacity of the PS will need 

to be confirmed by AWS operational staff 


have sufficient capacity; however the capacity of the PS will 

need to be confirmed by AWS operational staff 


have sufficient capacity; however the capacity of the PSs will 

need to be confirmed by AWS operational staff. 


have sufficient capacity; however the capacity of the PS will 

need to be confirmed by AWS operational staff 

Brook Street, Soham The majority of the network on the connection route is likely to 

have sufficient capacity; however significant growth is proposed 

and the capacity of the PSs will need to be confirmed by AWS 

operational staff. Local PS are also likely to be required and as 

such, new infrastructure may be needed and the site is assessed 

as Red on a precautionary basis 

Soham (Eastern gateway) The majority of the network on the connection route is likely to 

have sufficient capacity; however significant growth is proposed 

and the capacity of the PSs will need to be confirmed by AWS 

operational staff. New infrastructure may be needed and the site 

Land north-west of Regal 

Drive, 

is assessed as Red on a precautionary basis 

6.2.4 Soham Phasing Assessment 

Phase Dwellings Employment 


2010 – 2014 483 312 

2015 - 2019 483 311 

2020 - 2024 482 311 

2025 - 2031 482 311 

Total 1930 1245 


have sufficient capacity; however the capacity of the PSs will 

need to be confirmed by AWS operational staff. 


Resources 


Supply 

connect 

Infrastructure Constraints 

2011 

2011 

2011 

2011 

2015 

2015 

2011 


Pre-dev 

enquiry 

required? 

124 



6.3 Littleport Potential Development Areas 


dwellin 

Already built 


2001-10) 




Total 

Housing to be 

Assessed (=Total 


Employment 

Proposed jobs 



assessed 

gs 

571 

793 

221 

140 

1723 

1252 

jobs 

3165 

3165 


Sept 2011 




Assessment 



(Town wide) 

• The Ely planning Zone covering Littleport has sufficient water for all 

growth under future average conditions and sufficient water for 90% of 

the growth under peak/dry conditions 





Flood Risk • All proposed development falls within Flood Zone 1. However, this 

settlement forms an island surrounded by floodplain so consideration is 

needed for refuge and emergency measures in the event of a flood as 

it may be cut off from other larger areas. 



Management 

• Consideration should either be given to source control methods such 

as green roofs or a combination of infiltration techniques with large 

storage features such as retention basins. 

• The large proposed development site at Land at Highfield Farm would 

125 




Assessment 

Wastewater 

Treatment and 

water quality 

Ecology and 

Biodiversity 

6.3.2 SuDS Requirments 

be suitable for a large storage feature(s), with outflows to the small 

tributaries of the main river Ouse, which lies at to the east of the 

proposed development in the south west of Littleport. However, 

consideration should be given to the effects of potentially removing 

hydrological inputs to the watercourses to the west of Littleport. 

• All of the development sites proposed for Littleport are to the west of 

the town. The natural topography lends itself to these sites being 

drained into the Wood Fen Catchwater that is in the jurisdiction of the 

Littleport & Downham IDB. 

• WwTW does not have the capacity to accommodate projected growth. 

• Some process upgrades are required at the WwTW to treat to a stricter 

BOD consent and to most likely introduce P stripping; these upgrades 

will not be in place until AMP6 (2015 onwards). 

• Expansion of WwTW is likely to be possible if adjacent land became 

available. 

Constraint 

• Littleport Plains Lane WwTW was identified within the Stage 3 Review 

of Consents report as contributing to an ‘in combination’ effect on the 

SAC; although the RoC report comments that ‘the effect of … Littleport 

Plains Lane STW … is trivial against the input from the main STWs’. 

• Littleport WwTW can ensure no increase in loading for receiving 

watercourses after growth within the limits of conventional treatment. 

Assuming solutions are put in place to achieve this, growth in these 

catchments should not present an impact on the Ouse Washes 

Opportunity 

• Littleport is identified as being immediately to the west of an existing green corridor 

to be enhanced. There is potential for the enhancement of ecological value in this 

south-west area of the town through new SuDS opportunities linked to the new 

development which could provide habitat for Cambridgeshire BAP species and 

habitats such as grazing marsh, great crested newts or water voles. 


(Ha) 

Site at Highfield Farm, Ely Road, 

Littleport 


Littleport 

Land between Beech Court & Village 

College, Parsons Lane, Littleport 


area (Ha) 

1.707 1.37 624 - 849 


Volume (m 3 ) (1 in 100 + 

30% CC) 

26.7 21.36 9,693 – 13,238 

4.556 3.64 1,657 – 2,257 

Land North of Grange Lane, Littleport 2.131 1.70 774 – 1,054 

Land South of the Paddocks, Littleport 2.119 1.70 774 – 1,054

6.3.3 Wastewater Network constraints 


date to 

Site at Highfield Farm, 


Land at Highfield Farm, 


Land between Beech 

Court & Village College, 

Parsons Lane, Littleport 

Land North of Grange 

Lane, Littleport 


Sept 2011 

The majority of the network on the connection route is likely to have 

sufficient capacity; however development is upstream of a pumping 

station which may have limited capacity and may need to be 

upgraded 

The connection route is likely to have capacity downstream; 

however, upgrades would likely be required close to the site and 

sewer flooding may be exacerbated downstream. Capacity of 

pumping station is unknown. Solution is likely to be required 


sufficient capacity; however development is upstream of a pumping 

station which may have limited capacity and may need to be 

upgraded 




2010 – 2014 313 792 

2015 - 2019 313 791 

2020 - 2024 313 791 

2025 - 2031 313 791 

Total 1252 3165 


sufficient capacity; however there is a sewer flooding incident 

downstream and hence connection could exacerbate this problem. 

A new solution is therefore likely to be required 


Resources 


Supply 

connect 


2011 

2015 

2011 

2015 


Pre-dev 

enquiry 

required? 

126 



6.4 Bottisham Potential Development areas 


dwellin 

Already built 


2001-10) 




Total 

Housing to be 

Assessed (=Total – 

Already built) 

Employment 

Proposed jobs 



assessed 

gs 

26 

50 

50 

36 

162 

136 

jobs 

114 

680 


Sept 2011 




Assessment 



• This WRZ has a predicted surplus after growth for average and 

dry/peak demands hence sufficient supply for all growth 

Flood Risk • The proposed development site at Bell Road falls within Flood zone 1 



Management 

Wastewater 

Treatment and 

water quality 

• The soils around Bottisham are believed to be chalk, which is likely to be 

suitable for the use of infiltration SuDS. 

• The proposed development site at Bottisham is relatively small at just 1.6 

hectares and it is therefore possible that a combination of source control 

measures (e.g. green roofs) and infiltration techniques such as swales or 

permeable surfacing may be sufficient for this proposed development area. 

• There is a watercourse immediately adjacent to the proposed development 

site at Land east of Bell Road. This watercourse would provide a natural 

connection and outfall for an attenuation SuDS device such as a detention 

basin or balancing pond but would benefit from restriction of runoff to 

Greenfield rates 

• Bottisham WwTW does not have capacity to accommodate all of the 

projected growth and an increase in flow consent would be required to 

accommodate any growth 

• In order to maintain high status of ammonia in the receiving watercourse 

further discharge will not be permitted. 

127 




Assessment 

Ecology and 

Biodiversity 


• The Swaffham Bulbeck Lode would be unable to maintain ‘no 

deterioration’ from WFD high target for Ammoniacal-N downstream 

within the limits of conventionally applied treatment; therefore a 

solution is required in the long term and it is recommended that a 

technical advisory group is set up between EA, AWS, ECDC and CCC 

to investigate this. 

• Some initial phasing may be possible at an agreed restricted rate with 

AWS depending on available flow headroom (See 6.4.3 below) but this 

headroom is likely to be utilised initially by the 50 committed dwellings 

that have planning permission but have not yet been built. 

Constraint 

• It has been identified that water quality is not the major factor for the 

ecological condition of the Cam Washes SSSI and that Burwell WwTW 

and Bottisham WwTW are likely to make a relatively small contribution 

to phosphorus loads in the downstream River Cam, it is reasonable to 

conclude that the the impact of growth at Burwell and Bottisham is 

unlikey to impact on the condition of the Cam Washes. 

• The conclusions reached in this section will need to be verified at the 

project-level when a detailed solution is devised and the associated 

planning applications are made. 

Opportunity 

• Bottisham WwTW could contribute through enhanced water supply to the Vision 

area, aiding the conversion of farmland to fen habitat, although only where they will 

not also contribute to adverse water quality. This could render the process 

prohibitively expensive. 

• The ‘land east of Bell Road’ development area has potential for the enhancement of 

ecological value in this south-west area of the village through new SuDS 

opportunities linked to the new development which could provide habitat for 

Cambridgeshire BAP species and habitats such as grazing marsh, great crested 

newts or water voles. 


(Ha) 

Land East of Bell Road, Bottisham 



area (Ha) 

1.637 1.31 596 - 811 


date to 

Land east of Bell Road, 

Bottisham (Figure 3-6) 


sufficient capacity and there are no pumping stations likely to be 

limited by capacity; however, extensive new sewers are likely to be 

required to connect the site to the existing system 


Volume (m 3 ) (1 in 100 + 

30% CC) 

connect 

2011 

Pre-dev 

enquiry 

required?




2010 – 2014 34 170 

2015 - 2019 34 170 

2020 - 2024 34 170 

2025 - 2031 34 170 

Total 136 680 


Sept 2011 


Resources 


Supply 

6.5 Burwell Potential Development areas 


dwellin 

gs 

Already built 


2001-10) 




Total 

Housing to be 

Assessed (=Total – 

Already built) 

Employment 

Proposed jobs 



assessed 

256 

31 

115 

76 

478 

222 

jobs 

680 

680 






Assessment 



• This WRZ has a predicted surplus after growth for average and 

dry/peak demands hence sufficient supply for all growth 

128 




Assessment 

Flood Risk, • Proposed development falls in Flood zone 1 



Management 

Wastewater 

Treatment and 

water quality 

Ecology and 

Biodiversity 

• The soils around Burwell are believed to be chalk, which is likely to be 

suitable for the use of infiltration SuDS. 

• The proposed development site at Burwell is just under 7 hectares; 

assuming the proposed development will have 80% impermeable 

surfacing this would give 5.49 hectares of hardstanding from which 

surface water run-off would need to be sustainably disposed. It is 

therefore possible that infiltration devices alone may not be sufficient 

for this site (depending on infiltration rates) and therefore a 

combination of infiltration techniques and attenuation measures may 

be required. Source control techniques such as green roofs should 

also be incorporated into site design. 

• However, there are no main watercourses in the vicinity of the 

proposed development site and the smaller ditches may not have 

sufficient capacity to provide an outflow point from an attenuation 

pond. In addition to the infiltration assessment required for the detailed 

site design of the proposed development, an assessment of the 

channel capacity of the ditches adjacent to the land north of 

Newmarket Road site should be carried out. 

• An increase in flow consent would be required to accommodate any 

growth 

• Burwell Lode would be unable to maintain ‘no deterioration’ from WFD 

targets for Phosphate downstream within the limits of conventionally 

applied treatment; therefore a solution is required in the long term 

• Some initial phasing may be possible at an agreed restricted rate with 

AWS depending on available flow headroom (See 6.5.3 below) - but 

this headroom is likely to be utilised initially by the 31 committed 

dwellings that have planning permission but have not yet been built. 

Constraints 

• As determined by the Stage 3 Review of Consents (RoC) process for 

Wicken Fen it was considered that the increase in flow from Burwell 

WwTW would not have a direct impact pathway for effect on the 

Wicken Fen Ramsar site and does not represent an ecological 

constraint to growth. 

• It has been identified that water quality is not the major factor for the 

ecological condition of the Cam Washes SSSI and that Burwell WwTW 

and Bottisham WwTW are likely to make a relatively small contribution 

to phosphorus loads in the downstream River Cam, it is reasonable to 

conclude that the the impact of growth at Burwell and Bottisham is 

unlikely to impact on the condition of the Cam Washes. 

Opportunity 

• Burwell WwTW could contribute through enhanced water supply to the Vision area, 

aiding the conversion of farmland to fen habitat, although only where they will not 

also contribute to adverse water quality. This could render the process prohibitively 

expensive 

• Burwell is immediately to the east of a major green hub identified within the 

Cambridgeshire Green Infrastructure Strategy, namely the Wicken Fen Vision 

(discussed in more detail above). However, the key development area in Burwell is 

on the opposite side of the town and as such there are few, if any, opportunities for 

SuDS features to contribute to the Wicken Fen Vision. However, there is potential 

for the enhancement of ecological value in this eastern area of the village through 

new SuDS opportunities linked to the new development which could provide habitat


Assessment 



Sept 2011 

for Cambridgeshire BAP species and habitats such as grazing marsh, great crested 

newts or water voles. 


(Ha) 


area (Ha) 


Volume (m 3 ) (1 in 100 + 

30% CC) 

Land North of Newmarket Road, Burwell 6.862 5.49 2,499 – 3,403 



date to 

Land North of Newmarket 

Road, Burwell 




2010 – 2014 56 170 

2015 - 2019 56 170 

2020 - 2024 55 170 

2025 - 2031 55 170 

Total 222 680 


sufficient capacity and there are no pumping stations likely to be 

limited by capacity. 


Resources 


Supply 

connect 


2011 


Pre-dev 

enquiry 

required? 

129 




Sept 2011 

130 



7 Water Cycle Strategy Recommendations and Policy 

7.1 Policy Recommendations Overview 

The Detailed WCS has set out a series of policy recommendations which are summarised for 

each topic in this section. It is recommended that these policies are considered for inclusion in 

the LDF: 

7.1.1 Wastewater 

WW1 – development phasing Burwell 

Development in Burwell will need to be restricted to a minimal annual completion rate to be 

agreed with AWS and EA until a new solution is in place post 2015. 

WW2 – development phasing Bottisham 

Development in Bottisham will need to be restricted to a minimal annual completion rate to be 

agreed with AWS and EA until a new solution is in place post 2015. 

WW3 – WwTW expansion 

Expansion of the following WwTW sites should be supported: Witchford, Littleport and Soham. 

WW3 – development and sewerage network 

Development at sites indicated by the Detailed WCS to have potentially limited sewer network 

capacity should be subject to a pre-development enquiry with Anglian Water to determine 

upgrades needed to prior to planning permission being granted. 

7.1.2 Water Supply 

WS1 – Water Efficiency in new homes 

Ensure all housing is water efficient, new housing development must go beyond Building 

Regulations and as a minimum reach Code for Sustainable Homes Level 1/2 . 

WS2 – Water Efficiency Retrofitting 

Carry out a programme of retrofitting and water audits of existing dwellings and non-domestic 

buildings. Aim to move towards delivery of 10% of the existing housing stock with easy fit 

water savings devices 

WS3 – Water Efficiency Promotion 

Establish a programme of water efficiency promotion and consumer education, with the aim of 

behavioural change with regards to water use. 

7.1.3 Surface Water Management and Flood Risk 

SWM1 – sewer separation 

Developers should ensure foul and surface water from new development and redevelopment 

are kept separate where possible. Where sites which are currently connected to combined 

sewers are redeveloped, the opportunity to disconnect surface water and highway drainage 

from combined sewers must be taken.

7.1.4 Ecology 

SWM2 – above ground drainage 


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131 



Developers should aspire to achieve 100% above ground drainage for all future developments, 

where feasible. Where this is not feasible due to for example housing densities, land take, 

ground conditions, topography, or other circumstances, the development proposals should 

maximise opportunities to use SuDS measures which require no additional land take, i.e. green 

roofs, permeable surfaces and water butts. 

SWM3 – SuDS and Green Infrastructure 

Developers should ensure linkage of SuDS to green infrastructure to provide environmental 

enhancement and amenity, social and recreational value. SuDS design should maximise 

opportunities to create amenity, enhance biodiversity, and contribute to a network of green (and 

blue) open space. 

SWM4 – SuDS and Water Efficiency 

Developers should ensure linkage of SuDS to water efficiency measures, including rainwater 

harvesting. 

SWM5 – Linkages to SWMP and SFRA 

Developers should ensure SuDS design supports the findings and recommendations of the 

Cambridgeshire wide Surface Water Management Plan (SWMP) and East Cambridgeshire 

SFRA. 

SWM6 – Water Quality Improvements 

Developers should ensure, where possible, that discharges of surface water are designed to 

deliver water quality improvements in the receiving watercourse or aquifer where possible to 

help meet the objectives of the Water Framework Directive. 

There is no indication that additional discharges beyond the current volumetric consent at 

Burwell WwTW will result in adverse effects on Wicken Fen SSSI/SAC/Ramsar site (including 

Wicken Lode) provided that ‘no deterioration’ of the water quality of the Burwell Lode can be 

achieved. However, the hydraulic situation around Wicken Fen is highly complex and due to 

the limitations of the modelling/data available for this WCS it has not been possible to 

definitively confirm this conclusion with total certainty. As such, it is recommended that: 

ECO1 – Phasing at Burwell WwTW 

The Council includes a policy within its Core Strategy that ensures that phasing of housing to 

be connected to Burwell WwTW is timed such that it does not result in exceedence of the 

volumetric capacity before the WwTW is able to achieve the tightened P limit on its effluent 

discharge and that detailed assessment has confirmed that it is compatible with the 

requirements of both the WFD and the Conservation (Habitats and Species) Regulations 2010. 

ECO2 – Biodiversity enhancement 

It is recommended that the Council include a policy in its Core Strategy which commits to 

seeking and securing (through planning permissions etc) enhancements to aquatic biodiversity 

in East Cambridgeshire through the use of SuDS and other means as outlined in this WCS 

(subject to appropriate project-level studies to confirm feasibility including environmental risk 

and discussion with relevant authorities) in line with the Cambridgeshire Green Infrastructure 

Strategy.

7.2 Climate Change and the Water Cycle – Adaptation 

7.2.1 Planning and Climate Change 


Sept 2011 

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The Planning and Climate Change supplement to Planning Policy Statement 1 (PPS1) sets out 

how planning, in providing for the new homes, jobs and the infrastructure needed by 

communities, should help shape places with lower carbon emissions and resilience to climate 

change. This should take into account: the contribution to be made from existing and new 

opportunities for open space and Green Infrastructure to urban cooling, SuDS, conserving and 

enhancing biodiversity; known physical and environmental constraints on the development of 

land such as sea level rises, flood risk and stability, and take a precautionary approach to 

increases in risk that could arise as a result of likely changes to the climate. The PPS1 

supplement allows local planning authorities to implement higher sustainability standards than 

required in the Building Regulations, provided that: 

• there is a robust evidence base through WCS, CAMS, water stress classification, 

environmental assessment, or the Habitats Directive and Appropriate Assessment; 

• the standards used are nationally recognised, including Code for Sustainable Homes and 

BREEAM; 

• the standards can be viably achieved, and; 

• the policies are appropriately focussed and embedded within the Core Strategy and 

Development Plan Documents (DPDs) 117 

In line with the PPS1 supplement on climate change the requirement to meet CSH 5/6 in 

domestic dwellings and high levels of water efficiency in non-domestic buildings should be 

established in Development Plan Documents (DPDs). Additionally, the findings of the WCS, 

and evidence relating to climate change impacts within the East Cambridgeshire District, 

should be incorporated into any future Climate Change Strategy developed for the District. 

The Outline WCS identified that most of the water-cycle related evidence and future 

management plans currently in use are based on UKCIP02 predictions. A comparison between 

the UKCIP02 and UKCP09 projections indicated that the projections were broadly similar, and 

in most cases the UKCP09 projections present less extreme predictions for temperature, 

precipitation and sea level rise. As such, policy, planning and guidance documents produced 

using the UKCIP02 projections are based on projections that appear to be providing a worse 

case scenario. However, moving forward, it will be important to ensure that when available, 

new evidence / guidance / management plans are considered in all planning activities. Table 

7-1 provides a summary of the key documents that should be considered by East 

Cambridgeshire. 

Table 7-1: Water Related Planning Documents and climate change 

Document Produced By Date for Review 

AWS Water Resource 

Management Plan 

Anglian River Basin District River 

Basin Management Plan 

AWS Strategic Direction 

Statement 

AWS 2015 (though plan is reviewed annually) 

Environment Agency December 2015 

AWS 2015 (for period 2015 – 2040) 

117 edited from the Water Efficient Building website, more information is available at http://www.water-efficient- 

buildings.org.uk/?page_id=191

PPS25 Department for 

Communities and Local 

Government 

Nene and Great Ouse 

Catchment Abstraction 

Management Strategies 

UKCP09 Projections and 

Impacts 

7.3 Developer Guidance 


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133 



Unknown – likely to be dependent on future 

Government stance regarding top-down 

policy 

Environment Agency Yearly updates provided. Date of next full 

review unknown. 

UKCIP On-going – check website for further 

research and case studies for mitigation / 

adaptation (http://www.ukcip.org.uk/) 

Specific developer guidance has been provided throughout the various sections of this study 

report, in relation to each water cycle topic. In order to consolidate this advice, a developer 

checklist has been developed to assist developers in ensuring their development proposals 

meet with the requirements of the overall strategy developed for East Cambridgeshire. This 

checklist is included in Appendix 6. 

7.4 Further Recommendations 

7.4.1 Stakeholder Liaison 

It is recommended that key partners in the WCS maintain regular consultation with each other 

as development proposals progress. AWS and the MLC have engaged in a regular rolling 

consultation forum to discuss current and emerging issues, and it is recommended that ECDC, 

Cambridgeshire County Council and the EA consider a similar approach. MLC also attend a 

weekly ‘surgery’ at Fenland DC to alleviate previous problems and it is recommended that this 

approach continues to include issues raised in this WCS. 

It is a specific recommendation of this WCS that ECDC hold regular monthly workshops with 

both AWS and the Environment Agency to resolve capacity issues at both Burwell and 

Bottisham WwTW. 

7.4.2 Ecological Studies 

A detailed flow modelling study is required to investigate the flows in the lodes around Wicken 

Fen and particularly the potential for Burwell Lode to become hydrologically connected to the 

Fen and WIcken Lode under a range of future flow scenarios as a result of both an increase in 

the discharge volume from Burwell WwTW and the recent implementation of a project to pump 

water from Monks Lode during the winter which may affect the ability of Wicken Lode to 

continue to prevent backflow from Burwell Lode/Reach Lode. This study should also confirm 

that in such circumstances a consent limit of 0.25 mg/l of P will still be sufficient to prevent any 

deterioration of P loading in the Fen (including Wicken Lode). 

A specific further study is also required before the volumetric consents for Witcham WwTW and 

Littleport WwTW are exceeded to confirm that achieving ‘no deterioration’ within the receiving 

watercourses will be adequate to avoid significant deterioration of P loadings in the Ouse 

Washes (i.e. not compromise the achievement of a 0.33 mg/l P loading as per the target set by 

the EA RoC or the 0.1 mg/l P loading normally used under JNCC Common Standards 

Monitoring guidance, if considered more appropriate). 

Natural England have also requested the following additional studies: 

• Detailed studies to evaluate the impacts of increased discharges on wider biodiversity;


Sept 2011 

134 



• Water quality effects associated with discharges from Burwell and Bottisham WwTW on the 

Cam Washes SSSI; 

• Potential cumulative impacts (flood risk) of increased discharge from Burwell WwTW on 

Wicken Fen; 

• Potential cumulative flood risk impacts of Witcham, Witchford, Little Downham and Littleport 

WwTWs on the Ouse Washes. 

The conclusions of the ecological assessments contained within this WCS will need to be reexamined 

in more detail as part of any applications to increase the discharge consents for 

relevant WwTWs or planning applications associated with WwTW extensions to confirm their 

validity. 

7.4.3 WCS Periodic Review 

The WCS should remain a living document, and be reviewed on an annual basis as 

development progresses and changes are made to the various studies and plans that support 

it; these include: 

• five yearly reviews of AWS’ WRMP (next full review in 2015, although interim reviews are 

undertaken annually); 

• second round of RBMP updates; 

• Price review 14 (AWS’ business plan for AMP6 – 2015 to 2019); and 

• Climate change impact assessment milestones (see Table 7-1) 

It is also important to consider the change to Planning Policy Statements that will occur as a 

result of consolidation of national planning policy into a single National Planning Policy 

Framework and how this may affect the overall water cycle strategy.

Appendices 


Sept 2011 

135 




Sept 2011 

136 



Appendix 1: Legislative Drivers shaping the Stage 2 WCS 

Directive/Legislation/Guidance Description 

Birds Directive 2009/147/EC Provides for the designation of Special Protection Areas. 

Code for Sustainable Homes The Code for Sustainable Homes has been introduced to drive a stepchange 

in sustainable home building practice, providing a standard for 

key elements of design and construction which affect the sustainability 

of a new home. It will become the single national standard for 

sustainable homes, used by home designers and builders as a guide to 

development and by home-buyers to assist their choice of home. 

It will form the basis for future developments of the Building 

Regulations in relation to carbon emissions from, and energy use in 

homes, therefore offering greater regulatory certainty to developers. 

The Code sets out a minimum water demand per person as a 

requirement for different code levels. CLG is currently in consultation 

on proposals to make certain code levels mandatory for all new homes. 

At present, only affordable homes must reach a certain code. 

Eel Regulations 2009 Provides protection to the European eel during certain periods to 

prevent fishing and other detrimental impacts. 

Environment Act 1995 Sets out the role and responsibility of the Environment Agency. 

Environmental Protection Act 

1990 

Flood & Water Management Act 

2010 

Integrated Pollution Control (IPC) system for emissions to air, land and 

water. 

The Flood and Water Management Act 2010 is the outcome of a 

thorough review of the responsibilities of regulators, local authorities, 

water companies and other stakeholders in the management of flood 

risk and the water industry in the UK. The Pitt Review of the 2007 flood 

was a major driver in the forming of the legislation. Its key features 

relevant to this WCS are: 

• To give the Environment Agency an overview of all flood and 

coastal erosion risk management and unitary and county 

councils the lead in managing the risk of all local floods. 

• To encourage the uptake of sustainable drainage systems by 

removing the automatic right to connect to sewers and providing 

for unitary and county councils to adopt SuDS for new 

developments and redevelopments. 

• To widen the list of uses of water that water companies can 

control during periods of water shortage, and enable 

Government to add to and remove uses from the list. 

• To enable water and sewerage companies to operate 

concessionary schemes for community groups on surface water 

drainage charges. 

• To make it easier for water and sewerage companies to develop 

and implement social tariffs where companies consider there is 

a good cause to do so, and in light of guidance that will be 

issued by the SoS following a full public consultation. 

Future Water, February 2008 Sets the Government’s vision for water in England to 2030. The 

strategy sets out an integrated approach to the sustainable 

management of all aspects of the water cycle, from rainfall and 

drainage, through to treatment and discharge, focusing on practical 

ways to achieve the vision to ensure sustainable use of water. The aim 

is to ensure sustainable delivery of water supplies, and help improve 

the water environment for future generations. 

Groundwater Directive 

80/68/EEC 

To protect groundwater against pollution by ‘List 1 and 2’ Dangerous 

Substances.


Habitats Directive 92/44/EEC and 

Conservation of Habitats & 

Species Regulations 2010 


Sept 2011 

137 



To conserve the natural habitats and to conserve wild fauna and flora 

with the main aim to promote the maintenance of biodiversity taking 

account of social, economic, cultural and regional requirements. In 

relation to abstractions and discharges, can require changes to these 

through the Review of Consents (RoC) process if they are impacting on 

designated European Sites. Also the legislation that provides for the 

designation of Special Areas of Conservation, provides special 

protection to certain non-avian species and sets out the requirement for 

Appropriate Assessment of projects and plans likely to have a 

significant effect on an internationally designated wildlife site. 

Land Drainage Act 1991 Sets out the statutory roles and responsibilities of key organisations 

such as Internal Drainage Boards, local authorities, the Environment 

Agency and Riparian owners with jurisdiction over watercourses and 

land drainage infrastructure. 

Making Space for Water, 2004 Outlines the Government’s strategy for the next 20 years to implement 

a more holistic approach to managing flood and coastal erosion risks in 

England. The policy aims to reduce the threat of flooding to people and 

property, and to deliver the greatest environmental, social and 

economic benefit. 

Planning Policy Statements Planning policy in the UK is set by Planning Policy Statements (PPSs). 

These explain statutory guidelines and advise local authorities and 

others on planning policy and operation of the planning system. 

PPSs also explain the relationship between planning policies and other 

policies which have an important bearing on issues of development and 

land use. These must be taken into account in preparing development 

plans. 

Pollution Prevention and Control 

Act (PPCA) 1999 

A WCS helps to balance the requirements of various planning policy 

documents, and ensure that land-use planning and water cycle 

infrastructure provision is sustainable. 

The most relevant PPSs to WCS are: 

PPS1 – Delivering Sustainable Development; 

PPS3 – Housing; 

PPS4 – Planning for Sustainable Economic Growth 

PPS9 – Biodiversity and Geological Conservation 

PPS12 – Local Development Frameworks; 

PPS23 – Planning and Pollution control; and 

PPS25 – Development and Flood Risk 

Implements the IPPC Directive. Replaces IPC with a Pollution 

Prevention and Control (PPC) system, which is similar but applies to a 

wider range of installations. 

Ramsar Convention Provides for the designation of wetlands of international importance 

Urban Waste Water Treatment 

Directive (UWWTD) 91/271/EEC 

This Directive concerns the collection, treatment and discharge of 

urban waste water and the treatment and discharge of waste water 

from certain industrial sectors. Its aim is to protect the environment 

from any adverse effects caused by the discharge of such waters. 

Water Act 2003 Implements changes to the water abstraction management system and 

to regulatory arrangements to make water use more sustainable. 

Water Framework Directive 

(WFD) 2000/60/EC 

The WFD was passed into UK law in 2003. The overall requirement of 

the directive is that all river basins must achieve ‘good ecological 

status’ by 2015, or by 2027 if there are grounds for derogation. The 

WFD, for the first time, combines water quantity and water quality


Natural Environment & Rural 

Communities Act 2006 


Sept 2011 

138 



issues together. An integrated approach to the management of all 

freshwater bodies, groundwaters, estuaries and coastal waters at the 

river basin level has been adopted. It effectively supersedes all water 

related legislation which drives the existing licensing and consenting 

framework in the UK. 

The Environment Agency is the body responsible for the 

implementation of the WFD in the UK. The Environment Agency have 

been supported by UKTAG 118 , an advisory body which has proposed 

water quality, ecology, water abstraction and river flow standards to be 

adopted in order to ensure that water bodies in the UK (including 

groundwater) meet the required status 119 . These have recently been 

finalised and issued within the River Basin Management Plans (RBMP). 

Covering Duties of public bodies – recognises that biodiversity is core 

to sustainable communities and that Public bodies have a statutory 

duty that states that “every public authority must, in exercising its 

functions, have regard, so far as is consistent with the proper exercise 

of those functions, to the purpose of conserving biodiversity 

Water Resources Act 1991 Protection of the quantity and quality of water resources and aquatic 

habitats. Parts have been amended by the Water Act 2003. 

Wildlife & Countryside Act 1981 

(as amended) 

Legislation that provides for the protection and designation of SSSIs 

and specific protection for certain species of animal and plant among 

other provisions. 

118 The UKTAG (UK Technical Advisory Group) is a working group of experts drawn from environment and conservation agencies. It 

was formed to provide technical advice to the UK’s government administrations and its own member agencies. The UKTAG also 

includes representatives from the Republic of Ireland. 

119 UK Environmental Standards and Conditions (Phase I) Final Report, April 2008, UK Technical Advisory Group on the Water 

Framework Directive.


Sept 2011 

139 



Appendix 2: Detailed WwTW capacity assessment results 

Volumetric Capacity Assessment Results 

Table A2-1 shows the results of volumetric capacity assessment for each WwTW in the study area. WwTW 

assessed as Amber in the RAG assessment have been taken forward for consent modelling. 

Table A2-1 Initial Assessment of Developments up to 2031 

Relevant 

WwTW 

Current 

BOD 

95%ile 

consent 

(mg/l) 

Current 

Ammonia 

95%ile 

consent 

(mg/l) 

Current 

P 

consent 

mean 

(mg/l) 

Current 

Consented 

DWF (m 3 ) 

Current 

actual 

DWF (m 3 ) 

Original of 

actual 

DWF data 

2031 DWF 

(m 3 ) 

Isleham 45A 8 - 423 231 measured 268 

Soham 17A 8 2 120 As 

2,894 2,894 consented 

121 

3,699 2011 

Newmarket 122 12A 4 2 120 6100 4,122 

Burwell 14A 9 1 124 1,373 1,373 

Bottisham 20A 5 - 1,046 1,046 

calculated 

123 

As 

consented 1 

21 

As 

consented 1 

21 

4,143 

RAG 

1,472 2011 

1,101 2011 

Stretham 20A 20 - 500 206 measured 

As 

228 

Haddenham 20A 5 - 749 749 consented 1 

21 

793 2011 

Wilburton 20A - - 225 189 measured 204 

Ely Ouse 25A 15 2 120 4350 2,315 measured 3732 

Ely New 25A 10 - 1604 1,148 measured 

As 

1297 

Witchford 20A 12 - 730 730 consented 1 

21 

748 2011 

Littleport 15A 5 - 2,314 2,314 

As 

consented 1 

21 

2,821 2011 

Little 

Downham 

15A 10 - 431 402 

measured 

441 

Dependent 

on phasing 

Mepal 40A 25 - 180 165 measured 

As 

165 

Witcham 12A 6 - 1,328 1,328 consented 1 

21 

1,416 2011 

120 These WwTWs have a PE greater than 10,000 and discharge to ‘Sensitive Areas (Eutrophic)’ as designated under the UWWTD, it 

is therefore required that either: a) the effluent achieves 2 mg/l of P as an annual average; or b) 80% of influent P is removed by the 

treatment process. Although the WwTWs do not have a formal P consent value, it has been assumed for calculation purposes that a 

2mg/l consent standard applies. 

121 AWS requested that all WwTW that have had a new recent consent volume applied, should be treated as having no capacity. 

122 Newmarket WwTW is included in this assessment has wastewater draining from development in the ‘fringes’ of the town will drain 

to the WwTWs. Reference to the Forest Heath WCS shows an addition 1,919 properties connecting from Forest Heath DC and 

analysis here has shown there is capacity to accept growth from both authority areas 

123 Calculated has been used where measured flow wasn’t available or measured flow was different to calculated by greater than 

100% - this is to reflect that some measured flow provided by AWS was considered by AWS to be unreliable until a longer record of 

flow data is available. 

124 There is an AMP5 P-removal scheme due for completion before 2015 at Burwell WwTW; hence the current consent has been 

assumed to be 1mg/l for the purposes of future assessment.

Key 

Additional development can be accommodated within 

existing consent 

Flow consent will be breached new consent standards 

will be required 

Consents to meet no deterioration 


Sept 2011 

140 



Note that process improvements may be required at 

these “green” sites. 

Date indicates when the flow consent is likely to be 

breached 

No deterioration analysis has been carried out to provide an estimate of the quality consent required to 

prevent a deterioration of the WwTW discharge; the results are provided in table A2-2 below. Where no 

upstream flow/quality data or downstream targets have been provided, load standstill calculations have 

been used as a guide for the consents required up to 2031.

Table A2-2 No deterioration assessment 

Key 


Sept 2011 

Downstream target 2031 - consents required (see key) 

WwTW BOD Amm P 

Soham 

Burwell 

Bottisham 

Haddenham 

Witchford 

Littleport 

Little 

Downham 

Witcham 

High 

Target: 

4 mg/l 

High 

Target: 

4 mg/l 

High 

Target: 

4 mg/l 

Poor 

Target: 

2.5 mg/l 

Moderate 

Target: 

1.1 mg/l 

High 

Target: 

0.3 mg/l 

N/A – load standstill used 





Green Value – no change to current 

consent required 

Moderate 

Target: 

0.25 mg/l 

Good 

target: 

0.12 mg/l 

Poor 

Target: 

1.0 mg/l 

BOD 

95%ile 

(mg/l) 

12 

Amm 

95%ile 

(mg/l) 

>current 

consent 

141 

P mean 

(mg/l) 

9 4 0.25 

5 0.5 1 

19 4 1.9 

18 11 

1 

No 

change 

required 

12 4 1.7 

14 9 

No 

change 

required 

11 18 1.9 

Amber Value – consent tightening required, 

but within limits of conventionally applied 


Comments 

Targets provided by the Environment Agency 





Load standstill calculations used – Where no P 

consent is in place, a 2mg/l assumption has been 

applied to the current discharge 













Red Value – not achievable within limits of 

conventionally applied treatment processes

Consents to achieve ‘Good Status’ 


Sept 2011 

142 



Further analysis has been undertaken to establish likely consents required to meet WFD Good Status and this is reported in Table A2-3. These calculations are 

based on the assumption that the river upstream of the works is currently meeting WFD Good Status and has therefore only been carried out for works and 

consent parameters where the current downstream water quality is currently at less than good status 125 . 

Table A2-3 WFD good ecological status analysis 

Soham 

Burwell 

WwTW BOD Amm P 

Bottisham 

N/A ** 

N/A ** 

Downstream target Current consents required (without growth) 2031 - consents required (with growth) 

Good 

Target: 

0.6 mg/l 

Good 

Target: 

0.6 mg/l 

N/A ** N/A ** 

Good 

Target: 

0.12 mg/l 

BOD 95%ile 

(mg/l) 

Amm 95%ile 

(mg/l) 

P mean 

(mg/l) 

BOD 95%ile 

(mg/l) 

Amm 95%ile 

(mg/l) 

P mean (mg/l) 

2 0.37 1 0.32 

N/A * 1 1 

Good 

Target: 

0.12 mg/l 

* The water course in question is already at Good status. 

** The watercourse in question is already at High status 

0.14 0.13 

125 This analysis is only possible where flow data has been provided for the RQP (monte-carlo model) and therefore has not been undertaken for the WwTW where only load calculations were undertaken.

MASS BALANCE CALCULATION: MONTE CARLO METHOD 

Version 2.5 

Calculations done on 22/06/2011 at 11.24 

Name of discharge Soham future consent to meet good 

Name of river Soham Lode 

Name of determinand Phosphate 

UPSTREAM RIVER DATA 

INPUT DATA 

Mean flow 33264.0 

95% exceedence flow 11232.0 

Mean quality 0.09 

Standard deviation of quality 0.09 

90-percentile 0.17 

DISCHARGE DATA 


Standard deviation of flow 1156.0 



... or 95-percentile 2.00 

DOWNSTREAM RIVER QUALITY TARGET 

Quality target (Mean standard) 0.12 

RESULTS 

RIVER DOWNSTREAM OF DISCHARGE 



90-percentile quality 0.22 



Quality target (Mean) 0.12 

DISCHARGE QUALITY NEEDED 





99.5-percentile quality 1.68


Version 2.5 


Name of discharge Soham WwTW - current flows at LCT 




INPUT DATA 












RESULTS 







DISCHARGE QUALITY 







Version 2.5 


Name of discharge Soham WwTW - No deterioration 


Name of determinand Ammonia 


INPUT DATA 













Quality target 2.50 

Percentile 90.00 

RESULTS 







Quality target (90-percentile) 2.50 








Version 2.5 


Name of discharge Soham future consent to meet good 




INPUT DATA 















RESULTS 















Version 2.5 


Name of discharge Soham current consent to meet good 




INPUT DATA 















RESULTS 















Version 2.5 




Name of determinand BOD 


INPUT DATA 















RESULTS 















Version 2.5 


Name of discharge Soham - current consent to meet good status 




INPUT DATA 















RESULTS 















Version 2.5 


Name of discharge Burwell WwTW - No deterioration 

Name of river Burwell Lode 



INPUT DATA 














RESULTS 















Version 2.5 


Name of discharge Burwell No deterioration 




INPUT DATA 















RESULTS 















Version 2.5 


Name of discharge Burwell current consent to meet good 




INPUT DATA 















RESULTS 















Version 2.5 


Name of discharge Burwell No deterioration 




INPUT DATA 















RESULTS 















Version 2.5 


Name of discharge Bottisham No deterioration 

Name of river Swafham Bulbeck Lode 



INPUT DATA 














RESULTS 















Version 2.5 


Name of discharge Bottisham current consent to meet good 

Name of river Swaffham Bulbeck Lode 



INPUT DATA 














RESULTS 















Version 2.5 


Name of discharge Bottisham WwTW - current flows at LCT 

Name of river Swaffham Bulbeck Lode 



INPUT DATA 












RESULTS 







DISCHARGE QUALITY 







Version 2.5 






INPUT DATA 















RESULTS 















Version 2.5 






INPUT DATA 















RESULTS 















Version 2.5 






INPUT DATA 














RESULTS 















Sept 2011 

160 



Load Standstill outputs to support consent calculations

WITCHAM STW 

Scenario 1 

Current Quality Consents Current Load (kg/d) Increase in Load (kg/d) 

Year Flow (m3/d)Flow (Ml/d) BOD Amm P BOD Amm P BOD Amm P 

Current (2010) 1,328 1.660 12 6 2 19.9 10.0 3.3 0.0 0.0 0.0 

Future (2026) 1,416 1.770 12 6 2 21.2 10.6 3.5 1.3 0.7 0.2 

Future Quality Consents Future Load (kg/d) 

Year Flow (m3/d)Flow (Ml/d) BOD Amm P BOD Amm P 

Future (2026) 1,416 1.770 11.3 5.6 1.9 19.9 10.0 3.3

LITTLEPORT STW 

Current Quality Consents Current Load (kg/d) 

Increase in Load (kg/d) 

Year Flow (m3/d) Flow (Ml/d) BOD Amm P BOD Amm P BOD Amm P 

Current (2010) 2,314 2.893 15 5 2 43.4 14.5 5.8 0.0 0.0 0.0 

Future (2026) 2,768 3.460 15 5 2 51.9 17.3 6.9 8.5 2.8 1.1 

Future Quality Consents 

Future Load (kg/d) 

Year Flow (m3/d) Flow (Ml/d) BOD Amm P BOD Amm P 

Future (2026) 2,768 3.460 12.5 4.2 1.7 43.4 14.5 5.8

LITTLE DOWNHAM STW 

Current Quality Consents Current Load (kg/d) Increase in Load (kg/d) 

Year Flow (m3/d)Flow (Ml/d) BOD Amm P BOD Amm P BOD Amm P 

Current (2010) 431 0.539 15 10 2 8.1 5.4 1.1 0.0 0.0 0.0 

Future (2026) 441 0.551 15 10 2 8.3 5.5 1.1 0.2 0.1 0.0 

Future Quality Consents Future Load (kg/d) 

Year Flow (m3/d)Flow (Ml/d) BOD Amm P BOD Amm P 

Future (2026) 441 0.551 14.7 9.8 2.0 8.1 5.4 1.1

HADDENHAM STW 




Current (2010) 749 0.936 20 5 2 18.7 4.7 1.9 0.0 0.0 0.0 

Future (2026) 790 0.988 20 5 2 19.8 4.9 2.0 1.0 0.3 0.1 




Future (2026) 790 0.988 19.0 4.7 1.9 18.7 4.7 1.9

WITCHFORD STW 




Current (2010) 730 0.913 20 12 2 18.3 11.0 1.8 0.0 0.0 0.0 

Future (2026) 748 0.935 20 12 2 18.7 11.2 1.9 0.5 0.3 0.0 




Future (2026) 748 0.935 19.5 11.7 2.0 18.3 11.0 1.8


Sept 2011 

167 



Appendix 3: Water Resources Supply and Demand deficit 

- Outline position

Appendix 4: Alternative WwTW options 

Introduction 


Sept 2011 

169 



In order to allow growth in locations where the environmental capacity of the receiving 

watercourse would not permit increased discharge from the existing WwTW (e.g. Doddington 

or Bottisham), developers could consider the provision of a new wastewater treatment facility 

for an individual development, which could discharge to an alternative watercourse from the 

existing WwTW. 

This appendix gives a summary of the treatment options available and should by developers 

and planners as a guide for systems that may be appropriate to allow growth to proceed. 

Please note, the following are indicative of the treatment options available and the 

requirements of each type of system; further investigation would be required to establish the 

suitability of a particular system for an individual site. 

Sewage treatment options can be classified as follows: 

• preliminary treatment, which removes the gross solid pollution through simple processes 

such as screening (usually by bar screens) and grit removal. (through constant velocity 

channels); 

• primary treatment, which reduces the polluting load by significant amounts through 

processes such as sedimentation or settlement of solid material; 

• secondary treatment, which removes common pollutants, usually by a biological process; 

and 

• tertiary treatment, which is used for a ‘final’ polish of the effluent or to remove specific 

pollutants e.g. phosphate stripping using iron dosing or UV treatment to reduce bacterial 

loadings. 

The degree to which the effluent is treated, and thereby the quality of the final effluent, is 

dependent on the requirements of the receiving watercourse. This will be established by the 

Environment Agency during the issue of a consent to discharge, which is required for all 

discharges of treated sewage effluent to controlled waters (rivers, streams, groundwater or the 

sea). An application for a consent can take up to four months (or longer if complex) and this 

must be factored in to the planning application and site design. It is prudent to obtain a consent 

to discharge, or an indication from the Environment Agency that a consent would be issued, 

before planning a development that is reliant on on-site wastewater treatment. 

For the purposes of providing outline options for on-site wastewater treatment, it is assumed that 

secondary treatment would be sufficient. Tertiary treatment may be required, depending on 

individual sites’ requirements; see below for tertiary treatment options. 

Treatment options summary 

Primary treatment 

Pre-treatment and primary treatment of the raw effluent typically includes the following stages: 

• screening, in which the influent sewage water is screened to remove all large objects like 

cans, rags, sticks, plastic packets etc. carried in the sewage stream;


Sept 2011 

170 



• grit removal, in which the velocity of the incoming wastewater is adjusted to allow the 

settlement of sand, grit, stones, and broken glass that could damage pumps or other 

equipment; and 

• primary sedimentation, in which sewage flows through primary clarifiers or primary 

sedimentation tanks that are used to settle sludge while grease and oils rise to the surface 

and are skimmed off. 

Secondary treatment 

Secondary treatment degrades the biological content of the sewage (human waste, food waste, 

soaps, detergent etc). Most conventional wastewater treatment processes are aerobic, which 

means that the bacteria that break down pollutants within the effluent require oxygen to 

function. This therefore requires oxygen to be supplied to the treatment process, with a 

resulting high energy requirement. In addition, aerobic processes produce sludge as a byproduct, 

which is made of waste bacteria. Both of these factors make aerobic treatment more 

complicated to control, and therefore more costly than the alternative anaerobic option. 

The bacteria in ‘anaerobic’ processes do not use oxygen, which reduces the energy 

requirements and sludge production compared to aerobic processes, thereby making the 

processes cheaper and simpler. However, the main disadvantages of anaerobic processes are 

that they are much slower than aerobic processes and are only good at removing the organic 

waste; other pollutants such as nutrients are not as effectively treated. Anaerobic processes 

generally like ‘steady’ effluents and do not cope well with shock loads and changes in flow or 

composition of the effluent. .However, for treatment of domestic waste this should not be a 

problem; only if anaerobic treatment processes are proposed for employment could this be an 

issue. 

The following table below gives a summary of the common options for secondary sewage 

treatment.

Common options for secondary sewage treatment 

Treatment process Description Key features 

Activated sludge 

Rotating biological 

Percolating filters 

Submerged aerated 

filter 

Waste Stabilisation 

Pond 

Upflow anaerobic 

sludge blanket 

Oxygen is mechanically 

supplied to bacteria which 

feed on organic large 

material and provide 

treatment. 

Series of thin vertical 

contractor (or biodisc) 

plates which provide 

surface area for bacteria to 

grow 

Effluent passed through a 

loose bed of stones, or 

other filter media, and the 

bacteria on the surface of 

the media treats the 

effluent 

Units consist of specially 

designed structured media, 

suspended over a fine 

bubble membrane diffuser 

in a plastic or metal tank. 

Large surface area ponds 

(approx 8m2 per person 

required in UK) 

Anaerobic process using 

blanket to absorb pollution 


Sept 2011 

Sophisticated process with many mechanical and 

electrical parts, which also needs careful operator 

control. Produces quantities of sludge for disposal, 

but provides high degree of treatment (when 

working well). 

Plates are exposed to air and then the sewage by 

rotating with about 30 per cent immersion in 

sewage. Treatment is by conventional aerobic 

process. Used in small-scale applications in 

Europe. 

An aerobic process in which bacteria take oxygen 

from the atmosphere – it therefore requires no 

external mechanical aeration. Has moving parts 

which require maintenance. 

The structured media, with a high surface area to 

volume ratio, supports a biologically active film of 

micro-organisms, which treat the wastewater by 

using oxygen provided by diffused air from the 

membrane diffuser. 

Treatment is by the action of sunlight and algae, 

which provide the oxygen for bacterial treatment. 

Systems are very common in France and 

Germany. Yorkshire Water operates a system in 

Scrayinham, which won numerous awards, 

including the 2006 RSPB/CIWEM Living Wetland 

award. 

This process produces little sludge and has no 

oxygen or power requirements. 

171 

Treatment standard typically 

achieved 

Can achieve 15BOD:25SS 

without tertiary filters 

Other comments 



Used for larger sites, 1,000 PE and 

above 

Generally 

20BOD:30SS:10AmmN 

See section 1.2.2 for manufacturers’ 

achievable, but anything tighter 

contact details. 

e.g. 15BOD needs tertiary solids 

removal (sand filters/reed beds) 

Generally 

20BOD:30SS:10AmmN 

achievable, but anything tighter 



The footprint for percolating filters is 

higher than a package type aerated filter 

unit. 

Generally 

20BOD:30SS:10AmmN Proprietary systems are expensive to 

achievable, but anything tighter buy, but reliable and easy to operate 



Highly cost-effective compared 

to other systems, although a 

significant land area may be 

required, depending on the 

population. 

Produces a poorer quality 

effluent than other processes.

Sequencing Batch 

Reactor 


Sept 2011 

load This is more common in hot climates where it 

functions well. 

Effluent is treated in 

batches using anaerobic 

digesters or mechanical 

treatment and may 

therefore incorporate the 

unit described above. 

The installation consists of at least two identically 

equipped tanks with a common inlet, which can be Generally 

switched between them. The tanks have a “flow 20BOD:30SS:10AmmN 

through” system, with raw wastewater coming in at achievable, but anything tighter 

one end and treated water flowing out the other. e.g. 15BOD needs tertiary solids 

While one tank is in settle/decant mode the other is removal (sand filters/reed beds) 

aerating and filling. 

172 



Source: Wastewater treatment options, Jeremy Parr, Michael Smith and Rod Shaw, Water and Environmental Health at London and Loughborough.

Proprietary systems 


Sept 2011 

173 



The following is a selection of proprietary system manufacturers which may be able to provide 

a suitable system for use at one of the development sites. Please note, the following is not an 

exhaustive list and inclusion within the following list does not represent an endorsement or 

guarantee of the manufacturer. 

Klargester 

Klargester produce package plants that will treat wastewater from 1 to 300 people. The 

‘Envirosafe’ range will treat up to 60 m3/day, to high treatment standards (including nutrient 

removal). The ‘Biodisc’ and ‘Biotec’ range will treat up to 18 people, with effluent standards of 

better than 15mg/l BOD, 25mg/l SS and 15mg/l ammonia. 

http://www.klargester.com/index.html 

Conder 

Conder plants can treat wastewater from domestic populations of between 6 and 600 people. 

The largest plants (up to 600 PE) are from the Techflo SAF 60 – 600PE Modular Sewage 

Treatment Range. In standard configuration the plants offer treatment to a 20mg/lBOD: 30mg/l 

SS effluent quality standard, with options for 20, 10 or 5mg/l NH3 effluent quality .The modular 

system includes flow balancing, primary settlement/sludge storage, SAF Biozone (BOD 

removal and nitrification) and humus settlement as discrete stages. 

http://www.conderproducts.com/index.htm 

Balmoral 

Balmoral produces a range of wastewater treatment solutions, including septic tanks, 

continuous aeration plants and sequential batch reactors, as well as providing installation and 

maintenance services. Balmoral products can treat wastewater from domestic populations of 

between 6 and approximately 100 people. 

http://www.drainstore.com/balmoral-sewage-treatment-plants-brochure-c206.html 

Clearwater 

Clearwater Technology Ltd can provide pre-treatment plants, water treatment chemicals, 

effluent water treatment and water hygiene applications. It manages treatment programmes for 

water treatment systems to ensure compliance with current regulatory and legislative 

requirements. Clearwater does not produce proprietary systems, but can advise on the 

suitability and installation of other manufacturers’ systems. 

http://www.clearwater.eu.com/ 

SPE 

SPE are specialists in sewage pumps, sewage treatment plants, pumping stations, dirty water 

pumps and all types of waste water and off-mains drainage systems. SPE does not produce 

proprietary systems, but can advise on the suitability and installation of other manufacturers’ 

systems.

Tertiary treatment 


Sept 2011 

174 



Depending on the sensitivity of the receiving watercourse, the effluent quality produced by 

secondary treatment (typically around 15 mg/l BOD and 30 mg/l SS) may not be sufficient to 

protect the environment and tertiary treatment may be required. The purpose of tertiary 

treatment is to provide a final treatment stage to raise the effluent quality before it is discharged 

to the receiving environment. 

The table below gives a summary of the common options for tertiary sewage treatment. 

Common options for tertiary sewage treatment 

Treatment process Description Key features 

Filtration (sand filters 

or granular activated 

carbon) 

Nitrogen removal 

Phosphate removal 

UV Disinfection 

Reed beds and 

lagoons 

Filtration of the effluent through sand or 

granular activated carbon (similar to 

charcoal) 

The removal of nitrogen is effected 

through the biological oxidation of 

nitrogen from ammonia to nitrate 

(nitrification), followed by denitrification, 

the reduction of nitrate to nitrogen gas. 

Nitrogen gas is released to the 

atmosphere and thus removed from the 

water. 

Phosphorus removal can also be 

achieved by chemical precipitation, 

usually with iron or aluminium salts 

UV radiation causes damage to the 

genetic structure of microorganisms, 

making them incapable of reproduction. 

Sand filtration removes much of the 

residual suspended matter. Filtration 

over activated carbon, also called 

carbon adsorption, removes residual 

toxins 

Sand filters, lagooning and reed beds 

can all be used to reduce nitrogen, but 

the activated sludge process (if 

designed well) can do the job the most 

easily. 

The process results in excessive sludge 

production in the form of a phosphaterich 

sludge, which may be disposed of 

by land fill or to land as fertilizer 

To be effective, the process needs a 

high clarity of effluent to ensure no 

shielding from the UV radiation. UV also 

has high energy requirements and 

therefore carbon footprint 

Effluent flowing through or over the reed 

bed/lagoon (usually by gravity) is subject 

to further microbial treatment 

The process is very similar to aerobic 

conventional sewage treatment, as the 

same organisms are used, except that 

conventional treatment systems require 

artificial aeration.


Sept 2011 

175 



Appendix 5: FEH worksheets for flood flow estimates at 

Burwell, Bottisham and Soham WwTWs

East Cambridgeshire WCS 

Flood Estimation by FEH 

BURWELL LODE 

Job Number D129319 Date 22 nd June 2011 Page 1 of 12 

Originator Checked Rev Suffix Orig 

GH RS 2 Date Check 

SUMMARY .............................................................................................................................................2 

RATIONALE ...........................................................................................................................................3 

SUBJECT CATCHMENT .......................................................................................................................4 

STATISTICAL.........................................................................................................................................5 

QMED DATA TRANSFER.....................................................................................................................8 

FLOOD FREQUENCY............................................................................................................................9 

REVITALISED FSR/FEH RAINFALL RUNOFF METHOD ..............................................................10 

REFERENCES.......................................................................................................................................11 

APPENDIX A ........................................................................................ Error! Bookmark not defined. 

Page 1 of 12



BURWELL LODE 

SUMMARY 

Flood Estimation Handbook Calculations for: 

Burwell Lode, at the WwTW discharge point (TL59140 68780) 

Method Chosen for derivation of Peak Flows 

Peak flows were generated using the FEH statistical method. After a review of the results the 

value derived from the FEH statistical method user defined GEV method was chosen. 

User Defined GEV 

Q2 (QMED) 0.042 

Q5 0.059 

Q10 0.070 

Q20 0.084 

Q50 0.096 

Q100 0.107 

Q200 0.120 

Q500 0.138 

Q1000 0.153 

Page 2 of 12



BURWELL LODE 

RATIONALE 

Flood estimates are being undertaken for the contributing catchment for Burwell Lode, with 

the downstream boundary Burwell WwTW discharge point. This hydraulic modelling study 

will therefore be used to assess the catchment and estimate the peak flood flow for a range 

of return periods. Flow estimates have been carried out for what shall been known from this 

point forward as Burwell Lode WwTW. This document presents the hydrology used to 

estimate the flows for the Burwell Lode WwTW catchment. 

Flow estimations made for the entire catchment are based on station records updated as 

part of the HiFlows-UK project. 

Hi-Flows UK provides flood peak data and station information, at around 1,000 river flow 

gauging stations throughout the UK, for use with the statistical flood estimation methods set 

out in the Flood Estimation Handbook. The data are provided as both annual maxima and 

peaks-over-threshold. 

The Hi-Flows data originates from the hydrometric data archives held by the Environment 

Agency for England and Wales, the Scottish Environment Protection Agency for Scotland and 

the Rivers Agency for Northern Ireland. Additional data and background information have 

also been supplied by the National River Flow Archive, held at CEH Wallingford, and the 

University of Dundee. 

Data is presented on approximately 960 gauging stations, including photographs, indication 

of the stations suitability for estimation of QMED, and its use in pooling groups. 

Further information can be found at http://www.environment-agency.gov.uk/hiflows. 

Page 3 of 12



BURWELL LODE 

SUBJECT CATCHMENT 

Location 

Name of Site: Burwell Lode WwTW 

Name of watercourse: Burwell Lode 

Geology of catchment: Predominately chalk 

Catchment Descriptors 

AREA 1.9 

ALTBAR 8 

ASPBAR 236 

ASPVAR 0.25 

BFIHOST 0.825 

DPLBAR 1.49 

DPSBAR 11.9 

FARL 1.000 

FPEXT 0.8801 

LDP 3.05 

PROPWET 0.26 

RMED-1H 28.4 

RMED-1D 10.7 

RMED-2D 36.7 

SAAR 542 

SAAR4170 544 

SPRHOST 17.35 

URBCONC2000 -1.000 

URBEXT2000 0.000 

URBLOC2000 -1.000 

Catchment Adjustments 

If the answer to any of the following questions is yes then the catchment is potentially a 

problem catchment and extra care or additional field validation maybe necessary. There may 

also be adjustments to be made to the catchment descriptors. 

Is the catchment small? Area



BURWELL LODE 

STATISTICAL 

Initial Pooling Group 

Only data that is suitable for pooling from the Hi-Flows data set has been used to generate 

the pooling group. 

Details of the Initial Pooling Group are: 


Station 

Years of 

Distance 

data 

QMED AM L-CV L-SKEW Discordancy 

27073 (Brompton Beck @ Snainton Ings) 7.485 28 0.739 0.21 0.017 0.365 

29009 (Ancholme @ Toft Newton) 8.456 34 1.919 0.39 0.367 2.853 

33045 (Wittle @ Quidenham) 8.707 40 1.081 0.345 0.178 0.6 

32029 (Flore @ Experimental Catchment) 9.119 5 2.538 0.374 0.054 1.114 

76011 (Coal Burn @ Coalburn) 9.119 31 1.805 0.188 0.368 1.96 

33029 (Stringside @ Whitebridge) 9.137 43 2.661 0.241 -0.116 0.772 

20002 (West Peffer Burn @ Luffness) 9.18 41 3.299 0.292 0.015 0.464 

36009 (Brett @ Cockfield) 9.318 38 3.661 0.263 -0.103 0.675 

34005 (Tud @ Costessey Park) 9.549 47 2.971 0.317 0.261 0.721 

33054 (Babingley @ Castle Rising) 9.665 32 1.129 0.222 0.071 0.15 

203046 (Rathmore Burn @ Rathmore Bridge) 9.747 26 10.996 0.126 0.115 2.165 

45817 (Rhb Trib to Haddeo @ Upton (trib)) 9.769 15 1.317 0.304 0.313 1.118 

33032 (Heacham @ Heacham) 9.777 40 0.461 0.319 0.091 0.936 

72014 (Conder @ Galgate) 9.815 41 16.957 0.189 0.054 0.986 

33063 (Little Ouse @ Knettishall) 9.894 28 3.659 0.257 -0.105 0.884 

26003 (Foston Beck @ Foston Mill) 9.917 48 1.739 0.251 -0.016 0.237 

Total 537 

Weighted means 0.267 0.095 

Target Return Period = 100 

Years of Record = 537 

H2 = 6.3562 

An H2 value of 6.3562 indicates that the pooling group is heterogeneous and that a review of 

the pooling group is essential. 

Stations were reviewed using the graphs available within FEH-WINFAP. This was undertaken 

to ensure that the dataset used in extracting growth curves and growth factors is the most 

suitable based on availability and hydrological similarity to the subject site. 

Page 5 of 12



BURWELL LODE 

Pooling Group Revision/Justification 

A review of the Initial Pooling Group revealed that it was heterogeneous, and that a review 

was essential. 

Station Reason Status 

32029 Short record Removed from pooling group 

29009 Discordant Reviewed but not removed from pooling group 

Station 32029, was removed from the pooling group as it had a short record, 5 years. 

After removing station 32029, station 29009 was shown to be discordant, with a high value 

indicating a ‘more different’ dataset. However, a review of the AMAX series indicated that 

the peak flood event was on 26 th June 2007, when there was exceptional flooding across the 

UK. Therefore the station has not been removed from the pooling group. 

1st Revision Pooling Group 

Station 

Years of 

Distance 

data 










33054 (Babingley @ Castle Rising) 9.665 32 1.129 0.222 0.071 0.121 




72014 (Conder @ Galgate) 9.815 41 16.957 0.189 0.054 0.981 


26003 (Foston Beck @ Foston Mill) 9.917 48 1.739 0.251 -0.016 0.218 

Total 532 

Weighted means 532 0.261 0.096 

Total Record Length = 532 

H2 = 6.3066 


the pooling group is essential. It is our opinion that we have tested the group to rigorous 

criteria, removing stations where necessary. Due to the small, permeable and flat 

catchment, the similarity distance measure (‘distance’ in the above table) indicates that 

even at the initial pooling group stage, there are no hydrologically similar stations. 

Therefore this is considered to be the best pooling group available for the study site, using 

this approach. 

Page 6 of 12



BURWELL LODE 

A printout of ‘all diagnostic plots’ for the select distributions is included in Appendix A. 

Selected Distributions of Final Pooling Group 

G-o-F: goodness-of-fit ≡ z value 

Generalised Logistic – 2.3076 

Generalised Extreme Value (GEV) – -0.8503 

Pearson Type 3 (PE3) – -0.5083 

Generalised Pareto – -7.0846 

The Generalised Extreme Value and Pearson Type 3 produce an acceptable fit, to derive the 

growth curve. However, only the GEV will be used to derive the growth curve as this is 

deemed to be the most useful distribution after the Generalised Logistic for providing the 

best overall fit to UK data. 

QMEDcds = 0.056 m 3 /s (calculated by WINFAP when deriving the flood frequency curve, 

without urban adjustment). 

Page 7 of 12



BURWELL LODE 

QMED DATA TRANSFER 

This method involves transposing flood peak information from a nearby ‘donor’ catchment. 

A donor site is available for the Burwell Lode WwTW catchment and therefore QMED will be 

adjusted using this catchment. The donor site is at Swaffham Lode @ Swaffham Bulbeck 

(33052). 

CENTROID DISTANCE 8.09 

AREA 33.250 

BFIHOST 0.841 

FARL 0.998 

FPEXT 0.2017 

SAAR 567 

SPRHOST 13.70 

URBEXT2000 0.012 

RECORD LENGTH 39 

QMED AM 0.340 

QMEDcds 0.677 

Additional sites have been reviewed but due to the close proximity of the donor and subject 

catchments and the other similar catchment descriptors it has been deemed sufficient to 

Swaffham Lode @ Swaffham Bulbeck. 

Page 8 of 12



BURWELL LODE 

FLOOD FREQUENCY 

Urban adjustment applied to growth curve? YES/NO 

Permeable Catchment applied to growth curve? YES/NO 

Donor Catchment applied to growth curve? YES/NO 

These flow rates are based on the growth curve fittings from the final pooling group using a 

GEV distribution. 

Return Period 

Growth Curve Fitting 

User Defined 

Flow (m³/s) 

Q2 (QMED) 1.000 0.042 

Q5 1.398 0.059 

Q10 1.656 0.070 

Q25 1.997 0.084 

Q50 2.265 0.096 

Q100 2.549 0.107 

Q200 2.849 0.120 

Q500 3.277 0.138 

Q1000 3.626 0.153 

Page 9 of 12



BURWELL LODE 

REVITALISED FSR/FEH RAINFALL RUNOFF METHOD 

The ReFH model has not been undertaken as it has been found to perform poorly on 

permeable catchments as the typically subdued runoff response to rainfall input from this 

type of catchment results in unrealistically values. Therefore, a statistical approach, rather 

than the rainfall-runoff method, is preferred when the catchment is permeable. 

Page 10 of 12



BURWELL LODE 

REFERENCES 

Bayliss, A C; Black, K B; Fava-Verde, A and Kjeldsen, T R (2007), URBEXT2000 – a new FEH 

catchment descriptor. Calculation, dissemination and application, Defra/Environment 

Agency R&D Technical Report FD1919/TR. Defra. 

http://sciencesearch.defra.gov.uk/Document.aspx?Document=FD1919_5228_TRP.pdf. 

Institute of Hydrology (1999) ‘Flood Estimations Handbook’ Institute of Hydrology: Oxford, 

UK. 

Kjeldsen, T.R. 2009. Modelling the Impact of urbanisation on flood frequency relationships in 

the UK, Hydrology Research 41(5), p391-405. 

Kjeldsen, T. R., Stewart, E. J. et al (2005) ‘Revitalisation of the FSR/FEH rainfall-runoff 

method: R&D Technical Report FD1913/TR’ DEFRA/Environment Agency. 

Kjeldsen, T R, Jones, D A and Bayliss, A C (2008). Improving the FEH statistical procedures for 

flood frequency estimation, Science Report SC050050/SR. Environment Agency. Available 

from: http://publications.environment-agency.gov.uk/pdf/SCHO0608BOFF-e-e.pdf. 

Page 11 of 12



SOHAM LODE 




TABLE OF CONTENTS 

TABLE OF CONTENTS .........................................................................................................................1 

SUMMARY .............................................................................................................................................2 

RATIONALE ...........................................................................................................................................3 


STATISTICAL.........................................................................................................................................5 

DATA TRANSFER..................................................................................................................................7 


REVITALISED FSR/FEH RAINFALL RUNOFF METHOD ................................................................9 

REFERENCES.......................................................................................................................................10 


Page 1 of 11



SOHAM LODE 

SUMMARY 


Soham Lode, at the WwTW discharge point (TL 57790 74420) 



value derived from the FEH statistical method user defined GL method was chosen. 

User Defined GL 

Q2 (QMED) 2.559 

Q5 3.494 

Q10 4.061 

Q20 4.769 

Q50 5.298 

Q100 5.833 

Q200 6.377 

Q500 7.113 

Q1000 7.684 

Page 2 of 11



SOHAM LODE 

RATIONALE 

Flood estimates are being undertaken for the contributing catchment for Soham Lode, with 

the downstream boundary Soham WwTW discharge point. This hydraulic modelling study 

will therefore be used to assess the catchment and estimate the peak flood flow for a range 

of return periods. Flow estimates have been carried out for what shall been known from this 

point forward as Soham Lode WwTW. This document presents the hydrology used to 

estimate the flows for the Soham Lode WwTW catchment. 















Page 3 of 11



SOHAM LODE 


Location 

Name of Site: Soham Lode WwTW 

Name of watercourse: Soham Lode 



AREA 71.31 

ALTBAR 54 

ASPBAR 322 

ASPVAR 0.37 

BFIHOST 0.735 

DPLBAR 18.03 

DPSBAR 23.5 

FARL 0.999 

FPEXT 0.2502 

LDP 29.45 

PROPWET 0.26 

RMED-1H 10.9 

RMED-1D 30.4 

RMED-2D 37.4 

SAAR 571 

SAAR4170 580 

SPRHOST 20.59 

URBCONC2000 0.767 

URBEXT2000 0.051 

URBLOC2000 0.825 








SOHAM LODE 

STATISTICAL 






Station 

Years of 

Distance 

data 





33057 (Ouzel @ Leighton Buzzard) 1.304 27 7.572 0.166 -0.115 1.049 


33011 (Little Ouse @ County Bridge Euston) 1.441 47 3.829 0.319 0.037 0.632 

37003 (Ter @ Crabbs Bridge) 1.513 44 4.68 0.251 -0.022 0.056 


43017 (West Avon @ Upavon) 1.573 38 5.594 0.242 0.096 0.718 


54020 (Perry @ Yeaton) 1.617 45 10.653 0.149 -0.029 1.632 

68020 (Gowy @ Bridge Trafford) 1.617 29 15.362 0.145 -0.16 1.1 

37014 (Roding @ High Ongar) 1.647 45 10.6 0.254 -0.157 1.32 

Total 507 




H2 = 5.7164 








29009 Discordant Reviewed, but to remain in pooling group 

Station 29009, is shown to be discordant, with a high value indicating a ‘more different’ 

dataset. However, a review of the AMAX series indicated that the peak flood event was on 

26 th June 2007, when there was exceptional flooding across the UK. Therefore the station 

has not been removed from the pooling group. 

Page 5 of 11



SOHAM LODE 

It is our opinion that we have tested the group to rigorous criteria. This is therefore 

considered to be the best pooling group available for the study site. 



G-o-F: goodness-of-fit = z value 

Generalised Logistic – 1.0325 




The Generalised Logistic produces an acceptable fit, to derive the growth curve. 

QMED 

Unadjusted QMEDcds = 2.227 m 3 /s (calculated by WINFAP when deriving the flood 

frequency curve, without urban adjustment). 

The urban adjustment factor (UAF) is 1.149, calculated using methods in Kjeldsen (2009). 

Adjusted QMEDcds = 2.559 m 3 /s (calculated by WINFAP when deriving the flood frequency 

curve, with urban adjustment). 

Page 6 of 11



SOHAM LODE 

DATA TRANSFER 

As the catchment is considered to be urbanised (URBEXT2000>0.03), then the use of Data 

Transfer methods is not recommended (WIN-FAP User Guide). 

Page 7 of 11



SOHAM LODE 






General Logistic distribution. 

Return Period Growth Curve Fitting Flow (m³/s) 

Q2 (QMED) 1.000 2.559 

Q5 1.365 3.494 

Q10 1.587 4.061 

Q25 1.863 4.769 

Q50 2.070 5.298 

Q100 2.279 5.833 

Q200 2.492 6.377 

Q500 2.779 7.113 

Q1000 3.003 7.684 

Page 8 of 11



SOHAM LODE 


The ReFH model has not been undertaken as it has been found to not represent urbanised 

catchments very well, and the runoff response to rainfall input from this type of catchment 

results in unrealistically values. The catchment is also bordering on being permeable (low 

SPRHOST and high BRIHOST). Therefore, a statistical approach, rather than the rainfallrunoff 

method, is preferred when the catchment is urbanised. There are also no appropriate 

donor stations for adjustment of parameters within ReFH. 

Page 9 of 11



SOHAM LODE 

REFERENCES 






UK. 








Page 10 of 11



SWAFFHAM BULBECK LODE 




TABLE OF CONTENTS 

TABLE OF CONTENTS .........................................................................................................................1 

SUMMARY .............................................................................................................................................2 

RATIONALE ...........................................................................................................................................3 


STATISTICAL.........................................................................................................................................5 

DATA TRANSFER..................................................................................................................................8 


REVITALISED FSR/FEH RAINFALL RUNOFF METHOD ..............................................................10 

REFERENCES.......................................................................................................................................11 


Page 1 of 12




SUMMARY 


Swaffham Bulbeck Lode, at the Bottisham WwTW discharge point (TL54400 61400) 



value derived from the FEH statistical method user defined GL method was chosen. 

User Defined GL 

Q2 (QMED) 0.026 

Q5 0.036 

Q10 0.044 

Q20 0.056 

Q50 0.067 

Q100 0.080 

Q200 0.095 

Q500 0.119 

Q1000 0.141 

Page 2 of 12




RATIONALE 

Flood estimates are being undertaken for the contributing catchment for Swaffham Bulbeck 

Lode, with the downstream boundary Bottisham WwTW discharge point. This hydraulic 

modelling study will therefore be used to assess the catchment and estimate the peak flood 

flow for a range of return periods. Flow estimates have been carried out for what shall been 

known from this point forward as Swaffham Bulbeck Lode WwTW. This document presents 

the hydrology used to estimate the flows for the Swaffham Bulbeck Lode WwTW catchment. 















Page 3 of 12





Location 

Name of Site: Swaffham Bulbeck Lode WwTW 

Name of watercourse: Swaffham Bulbeck Lode 



AREA 0.51 

ALTBAR 10 

ASPBAR 22 

ASPVAR 0.31 

BFIHOST 0.867 

DPLBAR 0.58 

DPSBAR 6.5 

FARL 1.000 

FPEXT 0.6029 

LDP 1.04 

PROPWET 0.26 

RMED-1H 28.5 

RMED-1D 10.7 

RMED-2D 34.7 

SAAR 542 

SAAR4170 558 

SPRHOST 13.67 

URBCONC2000 0.762 

URBEXT2000 0.1422 

URBLOC2000 1.235 









STATISTICAL 






Station 

Years of 

Distance 

data 





32029 (Flore @ Experimental Catchment) 6.979 5 2.538 0.374 0.054 1.504 




44009 (Wey @ Broadwey) 7.669 31 1.679 0.345 0.259 0.504 

45816 (Haddeo @ Upton) 7.695 14 3.427 0.318 0.449 0.891 

27051 (Crimple @ Burn Bridge) 7.695 36 4.61 0.219 0.122 0.395 

54091 (Severn @ Hafren Flume) 7.703 33 5.91 0.188 0.283 2.742 


54092 (Severn @ Hore Flume) 7.775 33 6.32 0.116 -0.075 2.007 

28033 (Dove @ Hollinsclough) 7.877 29 4.608 0.262 0.406 0.58 

25003 (Trout Beck @ Moor House) 8.008 35 15.09 0.173 0.346 0.832 

44006 (Sydling Water @ Sydling st Nicholas) 8.013 34 0.861 0.231 0.087 0.167 

26802 (Gypsey Race @ Kirby Grindalythe) 8.027 9 0.142 0.236 0.134 0.267 


25019 (Leven @ Easby) 8.1 30 5.538 0.361 0.411 0.901 

91802 (Allt Leachdach @ Intake) 8.151 34 6.35 0.153 0.257 1.07 

25011 (Langdon Beck @ Langdon) 8.213 22 15.362 0.254 0.405 1.812 

206006 (Annalong @ Recorder 1895) 8.243 48 15.33 0.189 0.052 1 

Total 646 



Years of Record = 646 

H2 = 5.1016 






Page 5 of 12





A review of the Initial Pooling Group revealed that it was heterogeneous, and that a review 

was essential. 


32029 Short Record Removed 

26802 Short Record Removed 

54091 SAAR = 2514 Removed 


PROPWET = 0.83 

44006 FARL = 0.944 Removed 


The above stations were removed from the Initial Pooling Group to create the 1 st Revision 

Pooling Group. 

1st Revision Pooling Group 

Station 

Years of 

Distance 

data 








44009 (Wey @ Broadwey) 7.669 31 1.679 0.345 0.259 0.42 

45816 (Haddeo @ Upton) 7.695 14 3.427 0.318 0.449 0.889 

27051 (Crimple @ Burn Bridge) 7.695 36 4.61 0.219 0.122 0.631 


28033 (Dove @ Hollinsclough) 7.877 29 4.608 0.262 0.406 0.421 

25003 (Trout Beck @ Moor House) 8.008 35 15.09 0.173 0.346 0.994 


25019 (Leven @ Easby) 8.1 30 5.538 0.361 0.411 0.754 

25011 (Langdon Beck @ Langdon) 8.213 22 15.362 0.254 0.405 1.938 

206006 (Annalong @ Recorder 1895) 8.243 48 15.33 0.189 0.052 1.354 

Total 498 



H2 = 4.5555 


the pooling group is essential. It is our opinion that we have tested the group to rigorous 

criteria, removing stations where necessary. Due to the small, permeable and flat 

catchment, the similarity distance measure (‘distance’ in the above table) indicates that 

even at the initial pooling group stage, there are no hydrologically similar stations. 

Page 6 of 12




Therefore this is considered to be the best pooling group available for the study site, using 

this approach. 



G-o-F: goodness-of-fit ≡ z value 

Generalised Logistic – -1.2380 




The Generalised Logistic produces an acceptable fit, to derive the growth curve. 

QMED 

Unadjusted QMEDcds = 0.015 m 3 /s (calculated by WINFAP when deriving the flood 

frequency curve, without urban adjustment). 

The urban adjustment factor (UAF) is 1.149, calculated using methods in Kjeldsen (2009). 

Adjusted QMEDcds = 0.026m 3 /s (calculated by WINFAP when deriving the flood frequency 

curve, with urban adjustment). 

Station 33052 Swaffham Lode @ Swaffham Bulbeck is located further downstream of the 

study catchment. This has a much larger catchment (33.25km 2 ) and recorded AMED AM 

0.340 and QMEDcds 0.677. Therefore this station has not been used as a donor. 

Page 7 of 12




DATA TRANSFER 

As the catchment is considered to be urbanised (URBEXT2000>0.03), then the use of Data 

Transfer methods is not recommended (WIN-FAP User Guide). 

Page 8 of 12









General Logistic distribution. 

Return Period 

Growth Curve Fitting 

User Defined 

Flow (m³/s) 

Q2 (QMED) 1.000 0.026 

Q5 1.402 0.036 

Q10 1.709 0.044 

Q25 2.173 0.056 

Q50 2.589 0.067 

Q100 3.077 0.080 

Q200 3.653 0.095 

Q500 4.581 0.119 

Q1000 5.436 0.141 

Page 9 of 12





The ReFH model has not been undertaken as it has been found to not represent urbanised 

catchments very well, and the runoff response to rainfall input from this type of catchment 

results in unrealistically values. The catchment is also bordering on being permeable (low 

SPRHOST and high BRIHOST). Therefore, a statistical approach, rather than the rainfallrunoff 

method, is preferred when the catchment is urbanised. 

Page 10 of 12




REFERENCES 






UK. 








Page 11 of 12


Sept 2011 

211 



Appendix 6: Recommended Developer Checklist for 

compliance with the Water Cycle Strategy

Key 

Appendix A: Developer Checklist 

Water Cycle Strategy Recommended Policy 

Environment Agency, Internal Drainage Board and Natural 

England Policy and Recommendations 

Local Policy 

National Policy or Legislation 

Flood Risk Assessment Requirement Checklist Policy or Legislation 

1 Is the Development within Flood Zones 2 or 3 as defined by the flood zone 

mapping in the SFRA, or where SFRA coverage is not available, the 

published Environment Agency flood risk maps? 

2 Development is within Flood Zone 1: 

Site larger than 1 Ha? 

Site smaller than 1 Ha? 

3 

4 

Is the development residential with 10 or more dwellings or is the site 

between 0.5Ha and 1Ha? 

Is the development non-residential where new floor space is 1,000m 2 or the 

site is 1 Ha or more 

5 The development either constitutes major development or is considered to 

be in a high risk flood zone and requires a Flood Risk Assessment (in 

accordance with PPS25 and the relevant SFRA) and the Environment 

Agency are required to be consulted. 

6 The development constitutes major development and is likely to require a 

Flood Risk Assessment (in accordance with PPS25 and the relevant 

SFRA) but the Environment Agency may not be required to be consulted. 

Y - go to 5 

N - go to 2 

Y - go to 5 

Y - go to 3 

Y - go to 6 

N - go to 4 

Y - go to 6 

N - go to 7 

Go to 8 

Go to 8 

7 An FRA is unlikely to be required for this development, although a check 

should be made against the SFRA and with the LPA and IDB to ensure that 

Y – go to 8 

there is no requirement for a FRA on the grounds of critical drainage 

N – go to 9 

issues. Does the SFRA or does the LPA or IDB consider a Flood Risk 

Assessment (FRA) is required? 

8 

Has an FRA been produced in accordance with PPS25, the IDB standing 

advice and the relevant SFRA? 

Y/N or N/A 

PPS25, Flood & water 

Management Act 

Surface Water Runoff Policy or Legislation 

9 A) What was the previous use of the site? 

B) What was the extent of impermeable areas both before and after 

development? 

10 If development is on a Greenfield site, have you provided evidence that 

post development run-off will not be increased above the Greenfield runoff 

rates and volumes using SuDS attenuation features where feasible (see 

also 18 onwards). 

If development is on a brownfield site, have you provided evidence that the 

post development run-off rate has not been increased, and as far as 

practical, will be decreased below existing site runoff rates using SuDS 

attenuation features where feasible (see also 17 onwards). 

% before % after 

Y/N or N/A 

Y/N or N/A 

Environment Agency 

Requirement for FRA. 

PPS25

11 

12 

12 

Is the discharged water only surface water (e.g. not foul or from highways)? 

If no, has a discharge consent been applied for? 

A) Does your site increase run-off to other sites? 

B) Which method to calculate run-off have you used? 

Have you confirmed that any surface water storage measures are designed 

for varying rainfall events, up to and including, a 1 in 100 year + climate 

change event (see PPS25 Annex B, table B.2)? 

13 For rainfall events greater than the 1 in 100 year + climate change, have 

you considered the layout of the development to ensure that there are 

suitable routes for conveyance of surface flows that exceed the drainage 

design? 

14 

15 

Have you provided layout plans, cross section details and long section 

drawings of attenuation measures, where applicable? 

If you are proposing to work within 8 m of a watercourse have you applied, 

and received Flood Defence Consent from the Environment Agency or the 

relevant IDB? 

16 The number of outfalls from the site should be minimised. Any new or 

replacement outfall designs should adhere to standard guidance form 

SD13, available from the local area Environment Agency office. Has the 

guidance been followed? 

17 

18 

19 

20 

21 

22 

Y/N 

Y/N 

Y/N 

Water Resources Act 

1991 

PPS 25 

Y/N PPS25 

Y/N 

Y/N 

Y/N or N/A 

Y/N 

PPS25 Guidance Notes 


1991 

Land Drainage Act 1991 

Guidance Driven by the 


1991 

Sustainable Drainage Systems (SuDS) Policy or Legislation 

A) Has the SuDS hierarchy been considered during the design of the 

attenuation and site drainage? Provide evidence for reasons why SuDS 

near the top of the hierarchy have been disregarded. 

B) Have you provided detail of any SuDS proposed with supporting 

information, for example, calculations for sizing of features, ground 

investigation results and soakage tests? See CIRIA guidance for more 

information. 

http://www.ciria.org.uk/suds/697.htm 

D) Have you checked that any proposed SUDS meet with the minimum 

requirements of the SuDS Approving Body (SAB) 

A) Are Infiltration SuDS to be promoted as part of the development? If 

Yes, the base of the system should be set at least 1m above the 

groundwater level and the depth of the unsaturated soil zones between the 

base of the SuDS and the groundwater should be maximised. 

B) If Yes – has Infiltration testing been undertaken to confirm the effective 

drainage rate of the SuDS? 

A) Are there proposals to discharge clean roof water direct to ground 

(aquifer strata)? 

B) If Yes, have all water down-pipes been sealed against pollutants 

entering the system form surface runoff or other forms of discharge? 

A) Is the proposed development within areas of less permeable peat, till or 

Y/N 

clay identified in East Cambridgeshire? 

B) If yes, have alternative source control methods been considered such as 

Y/N 

permeable paving, reservoirs, green roofs or water recycling? 

A) Does proposed surface water drainage require use of smaller 

drains/channels to connect to a main river? 

B) If yes, has the relevant IDB been consulted? 

Have you shown that drainage will be 100% above ground, or where not 

possible (due to housing densities, land take etc) provided evidence as to 

why it is not possibke 

Y/N 

Y/N 

Y/N 

Y/N 

Y/N 

Y/N 

Y/N 

Y/N 

PPS25 Guidance & Flood 

& water Management Act 

Detailed WCS policy 

suggestion

23 Is the development area above a Source Protection Zone (SPZ)? 

25 

26 

27 

28 

29 

30 

31 

32 

33 

34 

35 

A) Is the development area above an inner zone (SPZ1)? 

B) If yes, discharge of Infiltration of runoff from car parks, roads and public 

amenity areas is likely to be restricted – has there been discussion with the 

Environment Agency as to suitability of proposed infiltration SuDS? 

A) For infill development, has the previous use of the land been 

considered? 

B) Is there the possibility of contamination? 

C) If yes, infiltration SuDS may not be appropriate and remediation 

required to be undertaken. A groundwater Risk Assessment is likely to be 

required (Under PPS23) Has this been undertaken before the drainage 

design is considered in detail? 

Have oil separators been designed into the highway and car parking 

drainage? 

PPG23: http://publications.environmentagency.gov.uk/pdf/PMHO0406BIYL-e-e.pdf 

Have you considered whether any of the SuDS proposed can be linked to 

Green Infrastructure plans as set out in the Detailed Water Cycle Study for 

East Cambridgeshire? 

If Y go to 23 

If N go to 24 

Y/N 

Y/N 

Y/N 

Y/N 

Y/N 

Groundwater Regulations 

1998 

PPS23 

Y/N PPG23 

Y/N 


suggestion 

Water Consumption Policy or Legislation 

Have you provided the expected level of water consumption to meet the 

minimum of Code for Sustainable Homes Level 1/2 as recommended by 

the Detailed Water Cycle Study 

http://www.planningportal.gov.uk/england/professionals/buildingregs/sustai 

nablehomes/ 

Is the proposed development likely to achieve a water consumption of less 

than or equal to 125 l/h/d as consistent with the Communities and Local 

Government Building Regulations Part G (2009)? 

Y/N 

http://www.communities.gov.uk/publications/planningandbuilding/partg2009 

divisionalletter and 

http://www.planningportal.gov.uk/uploads/br/BR_PDF_draftADG_2009.pdf 

Have you Provided details of water efficiency methods to be installed in 

houses? 

A) Have you confirmed whether the development will utilise rainwater 

harvesting and/or required tank sizes (see http://www.environmentagency.gov.uk/homeandleisure/drought/38559.aspx 

and 

http://publications.environment-agency.gov.uk/pdf/GEHO0108BNPN-E- 

E.pdf) 

B) Have you considered linkage of SuDS to rainwater harvesting or other 

water efficiency measures? 

Have you confirmed whether grey water recycling is to be utilised and 

provided details? 

Have you provided details of any proposed measures to increase public 

awareness and community participation in water efficiency? 

Y/N 

Y/N 

Y/N 

Y/N 

Y/N 

Y/N 


suggestion 

Pollution Prevention Policy or Legislation 

Have you provided details of construction phase works method statement, 

outlining pollution control and waste management measures? See PPG2, 

PPG5, PPG6, PPG21(http://www.environmentagency.gov.uk/business/topics/pollution/39083.aspx) 

and DTI Site Waste 

Management Plan, ( 

http://www.constructingexcellence.org.uk/resources/publications/view.jsp?i 

d=2568) 

Y/N 

PPG2, PPG5, PPG6, 

PPG21

37 

38 

40 

41 

42 

A) Have you provided details of pollution prevention measures for the life of 

the development, such as oil and silt interceptors? 

B) Have you considered whether permeable pavement areas are protected 

from siltation? 

C) Have you provided details of maintenance – as with the SuDS? 

Y/N 

Y/N 

Y/N 


suggestion 

Sewerage Policy or Legislation 

Where development is in a site indicated to have potential foul sewerage 

cpacity concerns (see detailed WCS) have you provided evidence to 

confirm that sewerage capacity is available via a pre-development enquiry 

with Anglian Water 

Y/N 


suggestion 

Conservation / Enhancement of Ecological Interest Policy or Legislation 

Have you considered that SuDS should link to green Infrastructure to 

maximise environmental enhancement and amenity? And in addition that 

any green infrastructure, such as the surface water system, links to the 

neighbouring green infrastructure (River Corridors) to assist the creation 

and maintenance of green corridors identified in the Cambridgeshire GI 

strategy? 

A) Have you shown the impacts your development may have on the water 

environment? 

B) Is there the potential for beneficial impacts? Have you considered, 

where possible the design of SuDS to deliver water quality improvements 

in the receiving watercourse or aquifer? 

Have you confirmed all ponds within 500m of the site boundary have been 

surveyed for presence of great-crested newt populations? 

Y/N 

Y/N 

Y/N 

Cambridgeshire GI 

strategy 

Cambridgeshire BAP & 


suggestion 

Town and Country 

Planning Regulations 

1999 

Y/N Habitats Directive 

Further information can be found in the Environment Agency’s guide for developers: 

http://www.environment-agency.gov.uk/business/sectors/32695.aspx

Appendix 7: Ecological background for statutory 

designated sites 

Cam Washes SSSI 


Sept 2011 

216 



The Cam Washes are a series of low lying pastures which are subject to seasonal flooding. 

This seasonal flooding, coupled with a range of grassland structure from damp short grassland 

to wet tussocky fields, with associated pools, ditches and river margins, together with relative 

freedom from disturbance makes this an important site for numbers and diversity of wintering 

and breeding wildfowl and waders. Many of these wetland species are now becoming 

increasingly scarce as breeding birds in lowland England due to loss of suitable habitat. 

Associated areas of scrub and scattered trees further enhance the value of the area for other 

birds, in particular, warblers. Although some of the grassland has been agriculturally improved 

much of the area retains a useful floristic diversity and one small relatively dry field is included 

largely on floristic grounds. 

The area is especially important for breeding waders and holds a notably high breeding density 

of snipe Gallinago gallinago. Other breeding species include redshank Tringa totanus, gadwall 

Anas strepera, teal Anas crecca and shoveler Anas clypeata. Good numbers of these species 

also winter on this site. 

Sedge warbler Acrocephalus schoenobaenus is a regular breeder on this site; reed A. 

scirpaceus and grasshopper Locustella naevia warblers have also been recorded. The value of 

the area to wintering wildfowl is enhanced by the availability of the nearby Wicken Fen Mere 

which provides loafing and roosting areas for a large population of wigeon Anas penelope in 

particular. These and other wintering wildfowl and waders use the Cam Washes as a feeding 

ground. As such the site is particularly important at times of flood when birds are unable to feed 

on the internationally important Ouse Washes due to deep flooding. 

The agriculturally unimproved pasture holds plant communities of the neutral grassland type 

typical of hay meadows. This is characterised by the presence of grasses such as sweet 

vernal-grass Anthoxanthum odoratum, crested dog’s-tail Cynosurus cristatus, meadow fescue 

Festuca pratensis, red fescue F. rubra, downy oat-grass Helictotrichon pubescens, Yorkshire 

fog Holcus lanatus, perennial rye-grass Lolium perenne and rough meadow-grass Poa trivialis 

together with herbs such as common knapweed Centaurea nigra, ribwort plantain Plantago 

lanceolata, cowslip Primula veris and red clover Trifolium pratense. Wetter areas hold slender 

tufted-sedge Carex acuta and greater pond-sedge C. riparia and associated dykes support 

water violet Hottonia palustris. The major value of the semi-improved wet and damp grassland 

area lies in their provision of feeding and breeding areas for the bird populations. They still, 

however, support some components of unimproved grassland, particularly on the wetter areas. 

Marsh marigold Caltha palustris, lady’s smock Cardamine pratensis and great burnet 

Sanguisorba officinalis are present on some fields. Taller grass washlands hold reed sweetgrass 

Glyceria maxima, reed canary-grass Phalaris arundinacea and common reed Phragmites 

australis together with a number of sedges (Carex riparia, C. acutiformis, C. acuta). 

The variety of habitat and the wet condition of much of this area indicates that its value to other 

fauna, in addition to birds, is likely to be similarly high, but this remains to be fully studied. 

The SSSI consists of three Management Units of which one (Unit 2) was determined to be 

‘unfavourable declining’ condition in the most recent condition assessment (2008 for that Unit). 

This was based on BTO Research Report no. 431 Survey and Assessment of the Birds of


Sept 2011 

217 



Berry Fen and Cam Washes SSSIs, Cambridgeshire and the Management Unit failed to meet 

the threshold for a ‘lowland damp grassland’ bird assemblage. 

Up to 200 Eurasian Wigeon (Anas penelope) were present in the 2008-2009 winter along with 

smaller numbers of other dabbling ducks and two Whooper Swans (Cygnus cygnus) and 

passage waders included up to 40 Avocet (Recurvirostra avosetta) in May 2009. 

The SSSI, consisting of a series of low-lying washland pastures, is nationally important for its 

numbers and diversity of breeding wildfowl and wading birds including snipe, redshank and 

teal. The Cam Washes are the third largest area of washland remaining in Cambridgeshire. 

Ouse Washes SAC 

The Ouse Washes are located in eastern England on one of the major tributary rivers of The 

Wash. It is an extensive area of seasonally flooding wet grassland ('washland') lying between 

the Old and New Bedford Rivers (which are hydraulically connected to the River Great Ouse) 

and acts as a floodwater storage system during winter months. The cycle of winter storage of 

floodwaters from the river and traditional summer grazing by cattle, as well as hay production, 

have given rise to a mosaic of rough grassland and wet pasture, with a diverse and rich ditch 

fauna and flora. The Ouse Washes were designated as an SAC for their population of spined 

loach. This fish is thought to be largely confined to oxygen rich waters where the substratum 

consists of fine, organic rich sediment. 

The Conservation Objective for the spined loach population of the site is to maintain the 

population at Favourable Condition. Specifically, there should be no reduction in densities from 

existing levels (and in any case no less than 0.1 m -2’ ), no change in extent of Spined Loach 

habitat (311 ha). Targets for defining favourable conservation status include: 

• At least three year-classes should be present at significant densities. At least 50% of 

the population should consist of 0+ fish 

• Maintain the characteristic physical form of the river channel 

• Maintain natural substrate character. 

• Maintain vegetation management to no more than 50% of the channel width (for 

submerged plants) and 50% of the bank length (for marginal fringing plants) 

• No artificial barriers significantly impairing essential fish movement 

• No stocking/transfers of fish species at excessively high densities 

• Biological water quality equivalent to Class ‘b’ in the Biological module of the General 

Quality Assessment scheme 

• Dissolved oxygen/ammonia/BOD equivalent quality to Chemical GQA Class ‘C’ 

• Soluble reactive phosphorus of 0.1 mg L-1 annual mean 

• Flow regime should be characteristic of the river. As a guideline, at least 90% of the 

naturalised daily mean flow should remain in the river throughout the year.

Ouse Washes SPA 


Sept 2011 

218 



The washlands support both breeding and wintering waterbirds. In summer, there are important 

breeding numbers of several wader species, as well as spotted crake Porzana porzana. In 

winter, the site holds very large numbers of swans, ducks and waders. During severe winter 

weather elsewhere, the Ouse Washes can attract waterbirds from other areas due to its 

relatively mild climate (compared with continental Europe) and abundant food resources. In 

winter, some wildfowl, especially swans, feed on agricultural land surrounding the SPA. The 

site was designated as an SPA for regularly supporting 64,392 waterfowl, including populations 

of European importance of the following migratory species: 

• Ruff 

• Spotted Crake 

• Bewick's Swan 

• Hen Harrier 

• Whooper Swan 

• Black-tailed Godwit 

• Gadwall 

• Shoveler 

• Pintail 

• Pochard 

• Wigeon 

The detailed targets for determining favourable condition are too extensive to be reproduced 

here but the overall conservation objective for the SPA bird populations is to maintain the 

designated species in favourable condition, which is defined in part in relation to their 

population attributes and in part to habitat attributes (such as maintaining the extent and 

structure of the lowland neutral grassland habitat on site). On this site favourable condition 

requires the maintenance of the population of each designated species or assemblage. 

Ouse Washes Ramsar site 

The Ouse Washes is designated as a Ramsar site for the following reasons: 

The site is one of the most extensive areas of seasonally-flooding washland of its type in 

Britain. 

The site supports several nationally scarce plants, including small water pepper Polygonum 

minus, whorled water-milfoil Myriophyllum verticillatum, greater water parsnip Sium latifolium, 

river waterdropwort Oenanthe fluviatilis, fringed water-lily Nymphoides peltata, long-stalked 

pondweed Potamogeton praelongus, hair-like pondweed Potamogeton trichoides, grass-wrack 

pondweed Potamogeton compressus, tasteless water-pepper Polygonum mite and marsh dock 

Rumex palustris. 

Invertebrate records indicate that the site holds relict fenland fauna, including the British Red 

Data Book species large darter dragonfly Libellula fulva and the rifle beetle Oulimnius major.


Sept 2011 

219 



The site also supports a diverse assemblage of nationally rare breeding waterfowl associated 

with seasonally-flooding wet grassland. 

The site supports a wintering waterbird assemblage of international importance 

Species occurring at levels of international importance are: 

• Tundra swan 

• Whooper swan 

• Eurasian wigeon 

• Gadwall 

• Eurasian teal 

• Northern pintail 

• Northern shoveler 

• Mute swan 

• Common pochard 

• Black-tailed godwit 


here but the overall conservation objectives for the Ramsar site are to maintain the designated 

habitats and species in favourable condition, which is defined in part in relation to their 


structure of the lowland neutral grassland and open water habitat on site). On this site 

favourable condition requires the maintenance of the population of each designated species or 

assemblage. 

Ouse Washes SSSI 

The site is one of the country’s few remaining areas of extensive washland habitat. It is of 

particular note for the large numbers of wildfowl and waders which it supports, for the large 

area of unimproved neutral grassland communities which it holds and for the richness of the 

aquatic fauna and flora within the associated watercourse. The capacity of the site to hold 

wintering and breeding waterfowl and waders is of international significance. Of particular note 

in the winter are the large numbers of teal Anas crecca, pintail Anas acuta, wigeon Anas 

penelope, shoveler Anas clypeata, pochard Aythya ferina and Bewick’s swan Cygnus bewickii. 

The grassland communities of the area are characterised by such grasses as reed and floating 

sweet-grass Glyceria maxima and G.fluitans, reed canary-grass Phalaris arundinacea, marsh 

foxtail Alopecurus geniculatus together with a variety of sedges and rushes. Typical herbs 

include amphibious bistort Polygonum amphibium, water-pepper Polygonium hydropiper and 

tubular water-dropwort Oenanthe fistulosa. 

The associated dykes and rivers hold a great variety of aquatic plants, the pondweeds 

Potamogeton spp. are particularly well represented. Other aquatic species include the fringed 

water-lily Nymphoides peltata, greater water-parsnip Sium latifolium and the four species of 

duckweeds Lemna spp. 

The limnological interest of the Ouse Washes is further diversified by the Old Bedford River 

and River Delph, both good examples of base-rich, sluggish, lowland rivers. The flora includes 

the fan-leaved water-crow foot Ranunculus circinatus, yellow water-lily Nuphar lutea,


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arrowhead Sagittaria sagittifolia, long-stalked pondweed Potamogeton praelongus, perfoliate 

pondweed Potamogeton perfoliatus, and river water-dropwort Oenanthe fluviatilis. The 

associated aquatic and semi-aquatic fauna is similarly diverse. 

In the most recent condition assessments, 17.32% of the site (by area) was judged to be in 

either favourable or ‘unfavourable recovering’ condition, while 82.67% was judged to be 

‘unfavourable no change’. The reasons for unfavourable condition are primarily given as 

‘inappropriate water levels’ although diffuse agricultural pollution was also identified as a 

contributory factor. 

More than 40% of the UK's aquatic plant species (over 260) are found here including Mousetail, 

Flowering Rush, Water Starwort, Whorled Water Milfoil, Water Dropwort, Marsh Woundwort, 

Great Willow herb, Fringed Water-lily and Water Parsnip. In addition to the Washes, the rivers 

themselves are important habitats, as are the ditches between them. 

Large areas of the SSSI, however, are affected by a combination of prolonged summer flooding 

and a combination of diffuse and point source pollution, resulting in 86% of the SSSI being 

classified as in unfavourable condition (982 hectares of which is on the RSPB’s reserve). In 

particular, inputs of nutrients have gradually eroded the quality of aquatic plant communities in 

the rivers and ditches, which were once some of the most diverse in Britain56. The high 

nutrient loadings have considerably increased mat forming duckweed communities in the 

ditches. The nutrient inputs are also affecting the quality of the wet grassland habitats which 

are a key feature of the Washes, a Biodiversity Action Plan (BAP) priority habitat, and support 

important numbers of breeding wading birds such as snipe, lapwing and redshank. 

Reference: Cathcart, R. 2002. Effects of nutrient loading on the ditch flora of the Ouse Washes: 

current impacts and potential mitigation. RSPB 


here but the overall conservation objectives for the SSSI are to maintain the designated 



structure of the lowland neutral grassland and open water habitat on site). On this site 

favourable condition requires the maintenance of the population of each designated species or 

assemblage. 

Wicken Fen SSSI 

Wicken Fen is designated a SSSI because of its Molinia meadows, which are a species rich fen 

community, and Calcareous fens with Cladium mariscus or sedge beds. The SSSI also 

supports populations of Great Crested Newt, and Spined Loach, which are protected species. 

This small remnant of the East Anglian peat fens is one of the best surviving examples and is 

unique in a Cambridgeshire context. The site supports a range of characteristic fenland 

communities and is notable for its diverse fauna and flora, in particular the invertebrate fauna 

and the relic fen flora. 

To the north of the Wicken Lode is the original peat fen. Here the site supports fen communities 

of carr and sedge. The carr scrub is largely of alder buckthorn Frangula alnus, buckthorn 

Rhamnus catharticus and sallow over a sparse vegetation of fen plants including the marsh 

fern Thelypteris palustris. The more open areas of sedge fen are typically of tall grasses, great 

fen or saw sedge Cladium mariscus, purple moor-grass Molinia caerulea, sedges Carex spp. 

and rushes Juncus spp. A large number of herbs are associated with this community such as 

milk parsley Peucedanum palustre, meadow rue Thalictrum flavum and yellow loosestrife


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Lysimachia vulgaris. To the south of the Wicken Lode, the area is of rough pasture land, 

reedbed and pools which are attractive to breeding wetland birds and to wintering wildfowl, the 

area being subjected to winter flooding. 

The dykes, abandoned claypits and other watercourses carry a great wealth of aquatic plants. 

Many, such as greater spearwort Ranunculus flammula and lesser water plaintain Baldellia 

ranunculoides are now uncommon elsewhere. 

In the most recent condition assessment, Wicken Fen SSSI was identified as being in 100% 

either favourable or ‘unfavourable recovering’ condition. 





structure of the fen, marsh and swamp, standing open water and canals and broadleaved, 

mixed & yew woodland habitat on site). On this site favourable condition requires the 

maintenance of the population of each designated species or assemblage. 

Wicken Fen Ramsar site (Wicken Fen is also part of Fenland SAC) 

Wicken Fen is designated a Ramsar site for meeting 2 of the Ramsar criteria: 

• Ramsar criterion 1 - One of the most outstanding remnants of the East Anglian peat fens. 

The area is one of the few which has not been drained. Traditional management has created 

a mosaic of habitats from open water to sedge and litter fields. 

• Ramsar criterion 2 - The site supports one species of British Red Data Book plant, fen violet 

Viola persicifolia, which survives at only two other sites in Britain. It also contains eight other 

nationally scarce plants (Carex appropinquata, Lathyrus palustris, Myriophyllum verticillatum, 

Oenanthe fluviatilis, Peucedanum palustre, Potamogeton coloratus, Potamogeton friesii, 

Potamogeton praelongus) and 121 British Red Data Book invertebrates. 

The National Trust commissioned the consultancy Ecology, Land and People, to carry out 

detailed research into the hydrology of the Sedge and Verrall’s Fen. 

The vegetation survey showed a number of NVC communties. Historical research showed that 

S2 Cladium mariscus swamp, and probably also M9 Carex rostrata-Calligeron mire, existed at 

Wicken, but neither are present now which probably reflects decline in water levels. 

Monthly water quality and sediment samples were collected and showed that the isolated 

internal dykes had the lowest nutrient levels. The boundary dykes and Wicken Lode were in 

good condition and were not degraded by eutrophic water. 

The water table recharges by rainfall input through the winter. There is no water input from 

Wicken Lode. This hydrological regime is in marked contrast to the 1930s, when the recharge 

was due to both rainfall and flooding by calcareous waters from Wicken Lode. 





structure of the fen, marsh and swamp, standing open water and canals and broadleaved, 

mixed & yew woodland habitat on site). On this site favourable condition requires the 

maintenance of the population of each designated species or assemblage.

East Cambridgeshire District Council Water Cycle Study Detailed ...

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