Book 3 | Case Studies - WSUD
Book 3 | Case Studies - WSUD
Book 3 | Case Studies - WSUD
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Water Sensitive Urban Design<br />
<strong>Book</strong> 3 | <strong>Case</strong> <strong>Studies</strong>
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Water Sensitive Urban Design<br />
<strong>Book</strong> 3 | <strong>Case</strong> <strong>Studies</strong><br />
Table of Contents<br />
1 | Introduction 4<br />
2 | <strong>WSUD</strong> in the Planning Phase: Renwick 5<br />
2.1 <strong>WSUD</strong> Objectives 6<br />
2.2 Constraints to <strong>WSUD</strong> 7<br />
2.3 Opportunities for <strong>WSUD</strong> 8<br />
2.4 Integration of <strong>WSUD</strong> into the development 9<br />
2.4.1 Water quality and flow management 9<br />
2.4.2 Stream rehabilitation 10<br />
2.4.3 Urban and open space design requirements 11<br />
2.5 <strong>WSUD</strong> outcomes 12<br />
2.6 Conclusions 12<br />
3 | <strong>WSUD</strong> in the Implementation Phase: The Ponds 13<br />
3.1 <strong>WSUD</strong> Objectives 14<br />
3.2 Constraints to <strong>WSUD</strong> 14<br />
3.3 Opportunities for <strong>WSUD</strong> 15<br />
3.4 Integration of <strong>WSUD</strong> into the development 15<br />
3.4.1 Water conservation 15<br />
3.4.2 Pollution control 16<br />
3.4.3 Flow management 16<br />
3.4.4 Stream rehabilitation 17<br />
3.4.5 Construction in a saline environment 17<br />
3.5 <strong>WSUD</strong> Outcomes 19<br />
3.6 Conclusions 19<br />
4 | <strong>WSUD</strong> in the Implementation Phase: Prince Henry 20<br />
4.1 <strong>WSUD</strong> Objectives 21<br />
4.2 Constraints to <strong>WSUD</strong> 21<br />
4.3 Opportunities for <strong>WSUD</strong> 22<br />
4.3.1 Water conservation and reuse 22<br />
4.3.2 Water quality treatment 22<br />
4.4 Integration of <strong>WSUD</strong> into the development 24<br />
4.5 <strong>WSUD</strong> Outcomes 26<br />
4.5.1 Water quality treatment 26<br />
4.5.2 Water conservation and reuse 26<br />
5 | Operation and Maintenance of <strong>WSUD</strong> treatment measures: Victoria Park 28<br />
5.1 <strong>WSUD</strong> Objectives 29<br />
5.2 Constraints to <strong>WSUD</strong> 29<br />
5.3 Opportunities for <strong>WSUD</strong> 30<br />
5.3.1 Overcoming site constraints 30<br />
5.4 Integration of <strong>WSUD</strong> into the development 31<br />
5.4.1 Water quality 31<br />
5.4.2 Water quantity 31<br />
5.4.3 Water conservation and reuse 31<br />
5.5 <strong>WSUD</strong> Implementation and Maintenance 32<br />
5.5.1 Establishment 32<br />
5.5.2 Maintenance - bioretention swales 33<br />
5.6 <strong>WSUD</strong> Outcomes 34<br />
5.7 Conclusions 34<br />
<strong>Book</strong> 3 | CASE STUDIES 3
Water Sensitive Urban Design<br />
1 | Introduction<br />
The four case<br />
studies illustrate<br />
how <strong>WSUD</strong> can<br />
be integrated into<br />
different stages of<br />
land development.<br />
4 <strong>Book</strong> 3 | CASE STUDIES<br />
This document (<strong>Book</strong> 3 of 4 in Landcom’s<br />
Water Sensitive Urban Design (<strong>WSUD</strong>)<br />
Strategy box set) presents four case<br />
studies which demonstrate the application<br />
of <strong>WSUD</strong> in a range of Landcom projects.<br />
Projects were selected to represent<br />
conditions that are typical of the extent of<br />
developments undertaken by Landcom,<br />
including greenfield and urban renewal<br />
developments, inner city and fringe areas.<br />
The four case studies illustrate how <strong>WSUD</strong><br />
can be integrated into different stages of<br />
land development – from planning through<br />
to implementation, as well as providing an<br />
understanding of the ongoing operation<br />
and maintenance of <strong>WSUD</strong> elements. The<br />
case studies include:<br />
••<br />
The planning phase – Renwick <strong>WSUD</strong><br />
strategy for a greenfields development<br />
to address stringent water quality<br />
requirements for developments within<br />
the Sydney Catchment Authority (SCA)<br />
area.<br />
••<br />
The implementation phase – The Ponds.<br />
A site-specific <strong>WSUD</strong> strategy is being<br />
implemented in an environment with<br />
a high salinity hazard. The outcomes<br />
of this carefully planned development<br />
include attractive and functional<br />
landscaping features that have<br />
contributed to the high desirability of<br />
the lots and the consequent good sales<br />
records.<br />
••<br />
The implementation phase – Prince<br />
Henry. An urban renewal project that<br />
looks to water management and its<br />
relationship with surrounding landuses,<br />
in this case a golf course. Elements of the<br />
strategy include stormwater treatment,<br />
harvesting and reuse through both the<br />
golf course and the development as<br />
well as greywater reuse.<br />
••<br />
The operation and maintenance<br />
phase – Victoria Park. This case study<br />
documents how working with the natural<br />
site topography and environment can<br />
lead to well built stormwater treatment<br />
devices that will provide years of service,<br />
and with landscape requirements no<br />
different to most urban green spaces.<br />
Each case study identifies <strong>WSUD</strong> targets,<br />
the natural environmental constraints and<br />
opportunities that informed the <strong>WSUD</strong><br />
strategy for each site, how the strategy<br />
targets were met, and the lessons learnt<br />
through the <strong>WSUD</strong> Strategy. The case<br />
studies provide examples of <strong>WSUD</strong><br />
elements with preliminary sizing of<br />
elements presented. They represent a<br />
conceptual design of opportunities and<br />
do not represent detailed designs.
Water Sensitive Urban Design<br />
2 | <strong>WSUD</strong> in the Planning Phase - Renwick<br />
BONG BONG ROAD<br />
GREAT<br />
SOUTHERN RAILWAY<br />
Western Drainage Chanel<br />
SW Minor Watercourse<br />
Main Waterway<br />
INKERMAN ROAD<br />
Billabong<br />
and Floodplain<br />
SW external<br />
catchment 49ha<br />
TC1<br />
BONG BONG ROAD<br />
SE Minor Watercourse<br />
TC2<br />
TC1 external<br />
catchment 55ha<br />
TC2 external<br />
catchment 90ha<br />
Legend<br />
External Catchment Boundary<br />
Renwick Development Boundary<br />
Minor Watercourse<br />
Major Watercourse<br />
Riparian Corridor<br />
Figure 1 - Waterways within Renwick<br />
The Renwick <strong>WSUD</strong> Strategy reflects the<br />
successful integration of social, cultural,<br />
environmental and economic objectives.<br />
This case study demonstrates the<br />
planning stage of the 116 hectares (ha)<br />
Renwick development in Mittagong,<br />
120 kilometres south west of Sydney.<br />
The development will provide up to 600<br />
dwellings, in a range of lot sizes including<br />
cottages, traditional houses and semi<br />
rural / half acre and acre blocks.<br />
The lands that form the Renwick<br />
development property have been<br />
extensively cleared and used for<br />
agricultural purposes. A number of<br />
streams flow through the Renwick site,<br />
illustrated in Figure 1.<br />
<strong>Book</strong> 3 | CASE STUDIES 5
Water Sensitive Urban Design<br />
Table 1 | <strong>WSUD</strong> targets for Renwick to reflect NorBE<br />
Objective<br />
Water Conservation<br />
Performance Measure and Target<br />
(a) Combination of water efficiency and reuse options – 40% reduction<br />
on base case.<br />
(a) 65% reduction in the mean annual load of Total Nitrogen (TN).<br />
Pollution Control<br />
Flow Management<br />
(b) 84% reduction in the mean annual load of Total Phosphorus (TP).<br />
(c) 91% reduction in the mean annual load of Total Suspended Solids<br />
(TSS).<br />
Post-development storm discharges = pre-development storm<br />
discharges for the 1.5 year ARI event<br />
The <strong>WSUD</strong><br />
strategy forms a<br />
core component<br />
of the Renwick<br />
masterplan.<br />
2.1 <strong>WSUD</strong> Objectives<br />
The site is located within Sydney’s<br />
water supply catchment, and any runoff<br />
from the site drains via the Nattai River<br />
into Warragamba Dam and Sydney’s<br />
potable water supply. Under SEPP 58<br />
the development must meet the SCA‘s<br />
Neutral or Beneficial Effect (NorBE) Test.<br />
This requirement translates into <strong>WSUD</strong><br />
objectives which are more stringent than<br />
the conventional Landcom requirements<br />
as outlined in <strong>Book</strong> 1, Table 1.<br />
Demonstration of neutral or beneficial<br />
effect (NORBE) of stormwater quality<br />
is achieved by comparing the pollutant<br />
concentration characteristics of postdevelopment<br />
scenarios against that for<br />
pre-development conditions.<br />
A cumulative probability function relates<br />
the probability at which contaminant<br />
concentrations fall below a reference level.<br />
A modelling approach is used to simulate<br />
existing catchment conditions and derive<br />
the cumulative probabilities for daily<br />
pollutant concentrations under existing<br />
and post-development conditions.<br />
Table 1 lists the resulting reductions in<br />
pollutant loads by attaining Neutral or<br />
Beneficial Effect outcomes as stipulated<br />
by the Sydney Catchment Authority.<br />
These targets are more stringent than<br />
conventional <strong>WSUD</strong> targets and may be<br />
regarded as stretch targets applicable<br />
only to sensitive environments.<br />
The <strong>WSUD</strong> Strategy has been developed<br />
to address:<br />
••<br />
Stormwater treatment to protect<br />
the quality of the water entering the<br />
Warragamba Catchment,<br />
••<br />
Flooding impacts to prevent detrimental<br />
impacts on receiving ecosystems<br />
••<br />
Potable water conservation to address<br />
water scarcity.<br />
A comprehensive stream rehabilitation<br />
plan has been developed as part of the<br />
<strong>WSUD</strong> strategy. This is to improve the<br />
condition of the degraded and unstable<br />
streams on site, caused by changes to<br />
hydrology and water quality that result<br />
from urban development. The stream<br />
rehabilitation will improve the landscape<br />
and amenity value of the riparian corridor<br />
for the local community.<br />
The <strong>WSUD</strong> strategy forms a core<br />
component of the Renwick masterplan.<br />
The masterplan brings together social,<br />
cultural, environmental and economic<br />
objectives and aims to meet best practice<br />
in these disciplines. The masterplan also<br />
aims to preserve the area’s ‘community<br />
feel’, character and rural setting. The<br />
character of the area stems from the<br />
development of significant gardens and<br />
the landscape in the European tradition in<br />
response to the cool temperate climate of<br />
the Southern Highlands.<br />
6 <strong>Book</strong> 3 | CASE STUDIES
Water Sensitive Urban Design<br />
Renwick site<br />
2.2 Constraints to <strong>WSUD</strong><br />
The poor ecological and geomorphological<br />
condition of the existing streams<br />
and the desire for a public open space<br />
of high value creates both difficult<br />
constraints and excellent opportunities<br />
for <strong>WSUD</strong> and stream rehabilitation.<br />
Constraints for the development are:<br />
••<br />
Renwick is located within a Sydney<br />
drinking water supply catchment and<br />
the development must demonstrate<br />
that it will have a neutral or beneficial<br />
effect on the quality of the runoff from<br />
the site. This requires Renwick to have<br />
a comprehensive stormwater treatment<br />
strategy beyond that typically employed<br />
on Landcom sites.<br />
••<br />
Rainwater tanks reduce the volume of<br />
stormwater that requires treatment.<br />
However, because rainwater tanks<br />
would reduce the volume of stormwater<br />
run-off to the drinking water supply<br />
catchment, tanks will not be used. This<br />
will place a greater demand on the space<br />
required for stormwater treatment and<br />
flow attenuation measures.<br />
••<br />
The site has a badly degraded stream<br />
that flows through the site. The stream<br />
channel is highly unstable, rapidly<br />
eroding and requires considerable<br />
reshaping work. This stream must be<br />
restored as part of the development.<br />
••<br />
Three external catchments upstream<br />
drain to Renwick and flood attenuation<br />
controls must be provided for flows<br />
from these catchments, increasing the<br />
demand for space for flood detention<br />
basins.<br />
••<br />
Most of the land surrounding the<br />
streams is now populated by pasture<br />
grasses, weedy shrubs and trees. These<br />
weeds have been declared noxious<br />
weeds and the site managers have a<br />
legal obligation to suppress or destroy<br />
these plants.<br />
••<br />
Sites of Aboriginal and European<br />
cultural heritage occur alongside the<br />
riparian corridor, impinging on the<br />
space available for riparian restoration<br />
and <strong>WSUD</strong> elements.<br />
••<br />
Activity in Renwick is focussed on the<br />
centre of the site. Consequently, the<br />
bulk of public open space, parkland, and<br />
community facilities are also located<br />
in this area and these require some<br />
stream realignment to accommodate<br />
the desired landform.<br />
<strong>Book</strong> 3 | CASE STUDIES 7
Water Sensitive Urban Design<br />
Renwick site<br />
2.3 Opportunities<br />
for <strong>WSUD</strong><br />
Landscaping will be<br />
used to engage the<br />
community to make<br />
maximum use of<br />
this area.<br />
••<br />
Large areas of open space have been<br />
set aside within Renwick (approximately<br />
25% of the site) to maintain the sense<br />
of open space that characterises<br />
the area. The position of the open<br />
space and riparian corridor along<br />
the centre of the development area<br />
gives an opportunity for the riparian<br />
corridor to define the character of<br />
the public open space, and to create<br />
natural habitat through the heart of an<br />
urban area. Thus <strong>WSUD</strong> and stream<br />
rehabilitation will be incorporated into<br />
the landscaping works that give the<br />
village its defining character.<br />
••<br />
Landscaping will be used to engage<br />
the community to make maximum use<br />
of this area. A stream corridor that is<br />
well used and valued by residents will<br />
be better maintained and protected<br />
through passive surveillance.<br />
••<br />
Urban development at Renwick will<br />
increase runoff to the downstream<br />
waterways. Therefore, stream works to<br />
stabilise the channel will also reshape<br />
the channel to accommodate these<br />
extra flows.<br />
••<br />
The stream rehabilitation work will<br />
stabilise the channel and protect the<br />
urban infrastructure from erosion and<br />
flooding.<br />
••<br />
Modifications associated with the<br />
stream works will be used to create<br />
more diverse in-stream habitats than<br />
occur within the site at present.<br />
8 <strong>Book</strong> 3 | CASE STUDIES
Water Sensitive Urban Design<br />
Analysis showed<br />
that the best<br />
treatment method<br />
was a combined<br />
wetland and<br />
bioretention<br />
system.<br />
2.4 Integration of <strong>WSUD</strong><br />
into the development<br />
2.4.1 Water quality and flow<br />
management<br />
In development of the <strong>WSUD</strong> strategy,<br />
modelling was undertaken using the<br />
Model for Urban Stormwater Improvement<br />
Conceptualisation (MUSIC), to assess<br />
compliance with the Neutral or Beneficial<br />
Effect (NorBE) requirements for water<br />
quality. The pollution concentrations were<br />
translated to the pollution load reduction<br />
targets for total suspended solids,<br />
total phosphorous and total nitrogen.<br />
Analysis showed that the best treatment<br />
method was a combined wetland and<br />
bioretention system. A treatment element<br />
corresponding to approximately 3% of the<br />
contributing impervious urban / road area<br />
was required. These treatment devices<br />
will remove pollutants to the SCA’s<br />
requirements for NorBE, prior to release<br />
to the stream.<br />
The water quality treatment areas will<br />
be located within the riparian buffer<br />
zone, between the development and the<br />
riparian corridor. In some areas of the<br />
development vegetated swales along<br />
low-density roads with wide reserves will<br />
be used to improve water quality. The<br />
raingardens will be planted with native<br />
grasses and ephemeral wetland species<br />
adapted to the intended inundation<br />
regime. The plants used are indigenous to<br />
the Southern Highlands Shale Woodlands<br />
species assemblage, thus ensuring<br />
ecological continuity between the riparian<br />
zone and the stormwater treatment<br />
devices.<br />
To reduce the impact of increased frequent<br />
flows from increased runoff volumes from<br />
urban catchments, discharges from the<br />
urban areas corresponding to the 1.5 year<br />
ARI flow will be attenuated to protect the<br />
downstream waterway from erosion. The<br />
location of detention areas are still to<br />
be determined and will be incorporated<br />
within the floodplain.<br />
A plan showing the location of proposed<br />
treatment measures is presented in<br />
Figure 2.<br />
<strong>Book</strong> 3 | CASE STUDIES 9
Water Sensitive Urban Design<br />
GREAT<br />
SOUTHERN RAILWAY<br />
INKERMAN ROAD<br />
BONG BONG ROAD<br />
BONG BONG ROAD<br />
Legend<br />
<strong>WSUD</strong> Elements<br />
Renwick Development Boundary<br />
Minor Watercourse<br />
Major Watercourse<br />
Riparian Corridor<br />
Figure 2 - <strong>WSUD</strong> treatment elements<br />
The stream<br />
rehabilitation<br />
strategy developed<br />
for Renwick’s<br />
waterways was<br />
designed to<br />
complement the<br />
<strong>WSUD</strong> and urban<br />
requirements of<br />
the site.<br />
2.4.2 Stream rehabilitation<br />
The stream rehabilitation strategy<br />
developed for Renwick’s waterways was<br />
designed to complement the <strong>WSUD</strong><br />
and urban requirements of the site. The<br />
objectives were:<br />
••<br />
Stabilisation of stream bed and<br />
banks to facilitate and promote the<br />
natural development of in-stream<br />
geomorphological processes. The<br />
stream works will create a dynamic<br />
stability where the natural stream<br />
forming processes of erosion and<br />
sediment deposition can take place<br />
within the confines of the channel but<br />
will not change dimensions during<br />
engineering timeframes, or damage<br />
nearby roads and housing infrastructure<br />
••<br />
Retention of valuable stream physical<br />
and hydraulic habitats where they exist,<br />
and creation of habitats where streams<br />
are degraded and habitat is poor or<br />
absent.<br />
••<br />
Revegetation of stream channels and<br />
marginal riparian zones with species<br />
indigenous to the area and appropriate<br />
to the hydraulic habitats created.<br />
••<br />
Making the riparian corridor accessible<br />
to the public through the adjoining<br />
public open space, so that the corridor<br />
can also become a source of community<br />
identity and a focal point for recreation,<br />
and consequently highly valued by the<br />
community.<br />
Such work is more intensive than the work<br />
most commonly done in streams, but the<br />
outcome of diverse, healthy functioning<br />
streams will add substantial value to the<br />
community that will be created in the<br />
urban development surrounding this<br />
riparian corridor.<br />
10 <strong>Book</strong> 3 | CASE STUDIES
Water Sensitive Urban Design<br />
Renwick will reflect the distinct nature of the Southern Highlands<br />
Stream rehabilitation will complement <strong>WSUD</strong><br />
objectives at Renwick<br />
The riparian<br />
corridors have<br />
been designed<br />
to accommodate<br />
or facilitate these<br />
activities without<br />
compromising the<br />
function and form<br />
of the stream.<br />
2.4.3 Urban and open space design<br />
requirements<br />
The riparian corridor will become an<br />
important component of public open<br />
space for the community and will be<br />
subject to a diversity of uses, such as:<br />
••<br />
The aboriginal heritage conservation<br />
areas<br />
••<br />
The Village Green adjacent to the<br />
riparian corridor will provide a focal<br />
point for community activity and<br />
recreation. A meander in the stream<br />
will be realigned to complement the<br />
Village Green parkland.<br />
••<br />
Informal access to the stream and in<br />
formal stream crossings (sandstone<br />
boulder riffle zones) will be built within<br />
the core riparian zone. Three public<br />
roads and several pedestrian paths will<br />
cross the stream.<br />
••<br />
Appropriate passive recreation<br />
activities such as pedestrian and cycle<br />
paths, and areas for play, relaxation and<br />
gathering will be located alongside and<br />
within riparian corridor buffer zone.<br />
The riparian corridors have been<br />
designed to accommodate or facilitate<br />
these activities without compromising<br />
the function and form of the stream. It is<br />
envisaged that by providing good public<br />
access to the riparian zone the community<br />
will gain an appreciation of the natural<br />
values of the streams and riparian<br />
corridors and a sense of ownership of<br />
these important natural resources.<br />
<strong>Book</strong> 3 | CASE STUDIES 11
Water Sensitive Urban Design<br />
Integration of water into a semi rural landscape | Bridgewater, South Camden<br />
The key to<br />
the successful<br />
integration of the<br />
various aspects of<br />
the site was the<br />
incorporation of<br />
<strong>WSUD</strong> early in the<br />
planning process.<br />
2.5 <strong>WSUD</strong> outcomes<br />
The outcomes of the <strong>WSUD</strong> strategy,<br />
supported by the riparian rehabilitation<br />
works are:<br />
••<br />
Meet SCA requirements for NorBE.<br />
••<br />
Low maintenance requirements. A<br />
well vegetated stream whose natural<br />
habitat evolves and matures requiring<br />
only minimal maintenance and remains<br />
resistant to weed infestation.<br />
••<br />
Preservation of the heritage values of<br />
the site.<br />
••<br />
A naturally functioning stream system<br />
where stream forming processes of<br />
erosion and sediment deposition<br />
can take place within the confines<br />
of the channel that will not change<br />
dimensions during engineering<br />
timeframes, or damage nearby roads<br />
and housing infrastructure.<br />
••<br />
An ecologically diverse and healthy<br />
stream containing a diversity of<br />
physical, hydraulic and biological<br />
habitats, and supporting a diversity<br />
of vegetation representative of the<br />
Southern Highlands Shale Woodland<br />
plant community.<br />
••<br />
Integration with urban design and<br />
engaging the community in a public<br />
space that fosters activity, appreciation<br />
and learning about natural systems,<br />
social interaction and recreation.<br />
2.6 Conclusions<br />
The <strong>WSUD</strong> strategy developed for<br />
Renwick illustrates how <strong>WSUD</strong> can be<br />
integrated into the masterplan and<br />
complements a range of site needs.<br />
The key to the successful integration<br />
of the various aspects of the site was<br />
the incorporation of <strong>WSUD</strong> early in the<br />
planning process. The master planning<br />
process identified many of the constraints<br />
and opportunities that the site presented.<br />
In Renwick Village, the public open<br />
space that surrounded the waterway<br />
was required to serve multiple functions,<br />
many of which were complementary.<br />
Careful planning allowed many facilities<br />
to be co-located and designed in such a<br />
way so as to complement each other. In<br />
this way the raingardens for water quality<br />
treatment could act as a buffer for the<br />
riparian corridor, while enhancing the<br />
experience of people using cycle ways or<br />
foot paths and recreation areas. Similarly,<br />
the restored waterway will provide a<br />
connection with nature in the public open<br />
space, while also providing ecological<br />
habitat and attenuating flows from the<br />
urban development. <strong>WSUD</strong> is most<br />
efficient if site-specific strategies can<br />
be developed that respond to the local<br />
environment. Such synergistic outcomes<br />
can only result by identifying the <strong>WSUD</strong><br />
requirements early in the master planning<br />
process.<br />
12 <strong>Book</strong> 3 | CASE STUDIES
Water Sensitive Urban Design<br />
3 | <strong>WSUD</strong> in the Implementation Phase - The Ponds<br />
Figure 3 - Aerial photograph of The Ponds in the<br />
Blacktown LGA, Sydney. The approximate<br />
development site boundary is indicated<br />
by the dotted line. Note the extensive<br />
erosion associated with the creek<br />
channel.<br />
The Ponds<br />
illustrates how<br />
Landcom has<br />
applied <strong>WSUD</strong> to a<br />
large development<br />
currently under<br />
construction in an<br />
environment with a<br />
high salinity hazard.<br />
The Ponds case study relates to the<br />
implementation phase of <strong>WSUD</strong>. The<br />
Ponds illustrates how Landcom has<br />
applied <strong>WSUD</strong> to a large development<br />
currently under construction in an<br />
environment with a high salinity hazard.<br />
The carefully planned development<br />
has overcome many constraints to<br />
construction and created attractive and<br />
functional landscaping that has led to<br />
positive environmental and economic<br />
outcomes.<br />
The Ponds is in Sydney’s North-West,<br />
between Quakers Hill and Rouse Hill in<br />
the Blacktown LGA. Second Ponds Creek<br />
is the main watercourse of the site and the<br />
development extends along both sides of<br />
the creek. The site consists of 320 ha of<br />
land, on which 3,200 lots will be built over<br />
10 years. A large portion (80 ha) of the site<br />
will be set aside for parklands and public<br />
open space. Most of the public open<br />
space occurs along the stream corridor.<br />
The area was cleared for grazing in the<br />
mid-1800s, and aerial photos show that<br />
by 1947 approximately 5 ha of the stream<br />
was affected by salt. Groundwater near<br />
the creek is highly saline and groundwater<br />
levels probably rose in the early 1900s in<br />
response to the clearing of the catchment.<br />
Extensive erosion had occurred along the<br />
creek, probably caused by saline scalds<br />
and exacerbated by disturbance from<br />
grazing livestock (Figure 3).<br />
<strong>Book</strong> 3 | CASE STUDIES 13
Water Sensitive Urban Design<br />
3.1 <strong>WSUD</strong> Objectives<br />
Stormwater management at The Ponds<br />
is directed at two principal management<br />
objectives:<br />
••<br />
The treatment of stormwater runoff<br />
to ensure the loads of stormwater<br />
pollutants discharged to Second Ponds<br />
Creek and downstream receiving<br />
waters do not adversely impact on the<br />
ecological health of these waterways.<br />
••<br />
Protecting the ecosystem health and<br />
channel form stability of Second Ponds<br />
Creek<br />
The Landcom <strong>WSUD</strong> targets were<br />
adopted for the site as summarised in<br />
Table 2.<br />
Table 2 | <strong>WSUD</strong> targets for The Ponds<br />
Objective<br />
Water Conservation<br />
Performance Measure and Target<br />
(a) Combination of water efficiency and reuse options – 40% reduction<br />
on base case.<br />
(a) 45% reduction in the mean annual load of Total Nitrogen (TN).<br />
Pollution Control<br />
Flow Management<br />
(b) 45% reduction in the mean annual load of Total Phosphorus (TP).<br />
(c) 80% reduction in the mean annual load of Total Suspended Solids<br />
(TSS).<br />
Post-development storm discharges = pre-development storm<br />
discharges for the 1.5 year ARI event<br />
3.2 Constraints to <strong>WSUD</strong><br />
Groundwater near the creek is saline and<br />
lies as little as 1m below the soil surface<br />
in low-lying areas. The saline soils and<br />
groundwater can cause environmental<br />
problems and damage to urban<br />
infrastructure in the following ways:<br />
••<br />
The water quality of streams can be<br />
detrimentally affected if salts from<br />
saline groundwater and soils leach into<br />
the waterway.<br />
••<br />
If saline soils are exposed they become<br />
highly erosive and dispersible and<br />
support very little vegetation.<br />
••<br />
A rising groundwater table may kill<br />
plants if the water table reaches the<br />
root zone, leaving the surface soil<br />
unprotected and susceptible to further<br />
erosion.<br />
••<br />
Salts that come into contact with urban<br />
infrastructure may cause the breakdown<br />
of cement and bricks, and promote<br />
the rusting of steel. Consequently all<br />
earthworks near the creek must not<br />
disturb the saline subsoil and must<br />
treat any exposed subsoil, and must not<br />
cause an increase in the height of the<br />
groundwater table.<br />
To avoid impacting or exacerbating the<br />
effects of salinity, the stormwater treatment<br />
measures used must be those that do not<br />
rely on infiltration of stormwater into the<br />
ground, where percolating stormwater<br />
may mobilise salts or raise the water table.<br />
It was not appropriate to use stormwater<br />
treatment wetlands in many locations.<br />
Too little water was available to sustain<br />
stormwater wetlands because of the high<br />
rates of evaporation in the region and the<br />
small size of the urban catchments.<br />
14 <strong>Book</strong> 3 | CASE STUDIES
The Ponds Boulevard<br />
Water Sensitive Urban Design<br />
Masterplan<br />
To Hambledon Road<br />
Ridgeline Drive<br />
To Hambledon Road<br />
Schofields Road<br />
Seconds Ponds Creek<br />
The Ponds Boulevard<br />
John Palmer<br />
Primary School<br />
YOU ARE<br />
HERE<br />
Riverbank Drive<br />
Proposed<br />
Primary School<br />
Proposed<br />
Council Park<br />
Fyfe Road<br />
Stanhope Parkway<br />
Conrad Road<br />
Belbourne Road<br />
Fyfe Road<br />
Keirle Road<br />
To Windsor Road<br />
To Sunnyholt Road<br />
Please note that the above masterplan is an artist’s impression and is to be used as a guide only. Whilst every care is taken to ensure that this plan is<br />
correct, it is indicative only and subject to change without notice. Purchasers must rely on their own enquires and the Contract for Sale.<br />
LAN0282_MasterPlan_brochure_V2.indd 3-4<br />
Figure 4 - Masterplan of The Ponds development showing the<br />
proximity of development to Second Ponds Creek<br />
28/10/08 12:24:28 PM<br />
3.3 Opportunities for <strong>WSUD</strong><br />
Large areas within the developments<br />
have been devoted to public open space,<br />
providing adequate area for stormwater<br />
treatment measures as shown in the<br />
masterplan and urban layout (Figure 4).<br />
Due to the elongated nature of the site<br />
along the creek, many urban catchments<br />
were small, and the corresponding<br />
area required for stormwater treatment<br />
devices was small. Stormwater treatment<br />
measures could be located along the edge<br />
of the watercourse making the connection<br />
to the stream relatively simple.<br />
Second Ponds Creek is highly degraded<br />
and required substantial reshaping and<br />
rehabilitation works, making it easier to<br />
incorporate the connection between<br />
stormwater treatment devices and the<br />
stream.<br />
3.4 Integration of <strong>WSUD</strong><br />
into the development<br />
<strong>WSUD</strong> elements have been designed to<br />
meet the current best practice objectives<br />
in pollutant load reduction and flow<br />
targets set by Landcom (Table 2).<br />
3.4.1 Water conservation<br />
The water conservation targets have been<br />
met by the supply of reclaimed wastewater<br />
from the Rouse Hill Recycled Water Plant.<br />
The reclaimed water is used for toilets and<br />
irrigation and equates to a BASIX score of<br />
approximately 50 for houses within The<br />
Ponds.<br />
<strong>Book</strong> 3 | CASE STUDIES 15
Water Sensitive Urban Design<br />
Figure 5 - A street tree<br />
bioretention system<br />
Figure 6 - A vegetated swale designed to convey runoff to Second Ponds Creek. Road runoff<br />
from all small flows is directed towards the filter media, where pollutants are removed.<br />
3.4.2 Pollution control<br />
Stormwater pollution control is achieved<br />
by using a combination of bioretention<br />
systems (Figure 5) and vegetated swales<br />
(Figure 6). Swales convey runoff and are<br />
effective in removing particulate pollutants<br />
from stormwater, while bioretention<br />
systems are effective for removing<br />
dissolved pollutants. Bioretention systems<br />
have been configured as small systems to<br />
support street trees and treat road runoff,<br />
and as large basins that treat runoff from<br />
many lots (Figure 7). The bioretention<br />
basins have been located in the public<br />
open space alongside Second Ponds<br />
Creek.<br />
Stormwater treatment wetlands were<br />
unsuitable for this site. It is difficult to<br />
maintain a permanent wetland water<br />
body in many locations at The Ponds due<br />
to the small catchment sizes and high<br />
evaporation rates. Bioretention systems<br />
were also preferred to wetlands as water<br />
treatment devices because the presence<br />
of water in bioretention systems is<br />
ephemeral – the ephemerality decreases<br />
the risk that stormwater will infiltrate into<br />
the ground and mobilise the salts in the<br />
subsoil layers. The hydraulic conductivity<br />
of the sandy loam bioretention filter media<br />
is significantly higher than the surrounding<br />
soils. Therefore the flow path of infiltrated<br />
stormwater in the bioretention system<br />
is well defined and exfiltration to the<br />
surrounding soils minimised. To avoid any<br />
impacts of infiltrating water on the water<br />
table of Second Ponds Creek, the bases<br />
of the bioretention systems will be lined<br />
to eliminate any likelihood of groundwater<br />
recharge by stormwater infiltration.<br />
3.4.3 Flow management<br />
To stabilise and protect the channel form<br />
of Second Ponds Creek, flood retarding<br />
basins were constructed to attenuate<br />
frequent small flood events to the intensity<br />
of pre-development floods. To make the<br />
most efficiently use of the flood detention<br />
areas, bioretention systems have been<br />
incorporated into the floor of these basins<br />
thus combining both flow and pollution<br />
control in the same device (Figure 7).<br />
16 <strong>Book</strong> 3 | CASE STUDIES
Water Sensitive Urban Design<br />
Figure 7 - A flood retarding basin that incorporates a<br />
bioretention system on the floor of the basin<br />
Figure 8 - Revegetation of Seconds Ponds Creek has been very<br />
successful. Good growth and plant survival has created a<br />
stable channel form.<br />
3.4.4 Stream rehabilitation<br />
Second Ponds Creek was extensively<br />
rehabilitated prior to the development<br />
of the urban areas (Figure 8). The<br />
stream rehabilitation works were<br />
directed at elimination of exposure of<br />
the B-horizon soil layer and rehabilitation<br />
of the geomorphic form of the existing<br />
watercourse. Natural stream templates<br />
in the area were used as a guide to how<br />
vegetation can stabilise and mitigate bank<br />
erosion. The landscape strategy for the<br />
rehabilitation of Second Ponds Creek was<br />
guided by these features. Key features<br />
of the proposed waterway rehabilitation<br />
works include:<br />
••<br />
The construction of regular rock bars to<br />
stabilise the bed profile of the creek.<br />
••<br />
The provision of a low flow channel with<br />
sufficient capacity to convey flows up<br />
to the 3-month Average Recurrence<br />
Interval (ARI) event.<br />
••<br />
The provision of a vegetated<br />
watercourse (mid-flow channel) with<br />
sufficient capacity to convey flows up to<br />
the 2 year ARI event.<br />
••<br />
The formation of flatter bank slopes<br />
with adequate coverage of A-Horizon<br />
soil layer.<br />
••<br />
The planting of the mid-flow channel<br />
with appropriate vegetation with<br />
sufficient density to enable adequate<br />
bank erosion protection in addition<br />
to its habitat and other riparian zone<br />
function attributes.<br />
3.4.5 Construction in a saline<br />
environment<br />
<strong>WSUD</strong> at The Ponds required a very<br />
site-specific solution. One of the keys<br />
to successful <strong>WSUD</strong> in a salinity hazard<br />
area was involving the geo-technical<br />
specialists in the planning stages. A<br />
thorough site investigation identified the<br />
site hazards and formed the basis of the<br />
salinity management plan for the site. The<br />
salinity management plan was updated<br />
as required as new information became<br />
available and as the project progressed.<br />
Geotechnical specialists supervised the<br />
earthworks to ensure that the salinity<br />
hazard was managed at all times. This<br />
well informed approach ensured that<br />
contractors could cost work realistically<br />
and the earthworks were successful and<br />
stable. The result was good plant growth<br />
throughout the riparian corridor and a<br />
durable, well-functioning riparian zone.<br />
<strong>Book</strong> 3 | CASE STUDIES 17
Water Sensitive Urban Design<br />
Figure 9 - A flood retarding basin that incorporates a bioretention system on the floor of the basin. The<br />
basin will be properly vegetated when earthworks in the catchment are completed<br />
To ensure that bioretention systems<br />
function properly it is important to<br />
exclude the effects of salinity in order to<br />
promote good plant growth, and good<br />
plant growth is important to providing<br />
good water quality treatment.<br />
Some ornamental ponds have been built<br />
throughout the development to improve<br />
the amenity of the public open spaces.<br />
Since it was important to avoid exposure<br />
of sodic subsoils, and to prevent<br />
stormwater from interacting with the<br />
subsoils or saline groundwater, the basins<br />
for the ornamental ponds were lined with<br />
suitable non-sodic soils taken from other<br />
areas of the site. The soil liner used was<br />
suitably impermeable so that water from<br />
these ponds did not infiltrate into the<br />
subsurface soils below. The soil layer also<br />
acted to cap any sodic subsoils that may<br />
have been exposed during earthworks<br />
so that these areas could be stabilised<br />
and vegetated and thus protected from<br />
weathering and erosion.<br />
Bioretention systems are susceptible<br />
to clogging and require protection<br />
from sediment. Since high sediment<br />
loads are generated from developing<br />
catchments, the construction of the<br />
bioretention systems will not be fully<br />
completed until the construction work<br />
of the roads, infrastructure and housing<br />
lots has been finished. All of the<br />
earthworks for the bioretention systems<br />
have been completed, the media is in<br />
place and grasses have grown across the<br />
filter media surface. The batters will be<br />
planted to enhance the visual amenity<br />
of the bioretention systems. Once the<br />
earthworks in each of the bioretention<br />
system catchments have been<br />
completed, the sediment that has built up<br />
on the bioretention media surface will be<br />
removed and the media will be properly<br />
vegetated (Figure 9).<br />
18 <strong>Book</strong> 3 | CASE STUDIES
Water Sensitive Urban Design<br />
Proposed water quality treatment within the public domain | The Ponds<br />
The parks and<br />
green spaces<br />
throughout the site<br />
were constructed<br />
and established<br />
early to make the<br />
development<br />
attractive to buyers.<br />
3.5 <strong>WSUD</strong> Outcomes<br />
The focus on the waterway at the centre of<br />
the community has provided the impetus<br />
for extensive rehabilitation of Second<br />
Ponds Creek, and <strong>WSUD</strong> was incorporated<br />
to protect the ecosystem health of the<br />
creek. The parks and green spaces<br />
throughout the site were constructed and<br />
established early to make the development<br />
more attractive. The riparian corridor was<br />
densely vegetated to quickly stabilise<br />
the channel form and create a visible<br />
vegetated corridor throughout the site.<br />
The revegetation of the stream has been<br />
very successful and most of the planting<br />
has survived and grown well. As a result,<br />
not only was the channel form protected<br />
but the landscaping for the site was visible<br />
to buyers when the lots were released for<br />
sale. Having well-developed landscape<br />
features has contributed to the higher<br />
desirability of the lots for sale, which was<br />
reflected in good sales records for The<br />
Ponds.<br />
3.6 Conclusions<br />
The development at The Ponds is an<br />
example of <strong>WSUD</strong> being successfully and<br />
consistently applied over a large area.<br />
This was made effective by adapting the<br />
<strong>WSUD</strong> strategy to the site constraints<br />
and accommodating the salinity hazard,<br />
the topography, and accounting for high<br />
evaporation rates and relatively small<br />
catchment sizes. The success of this<br />
strategy was facilitated by the integration<br />
of stormwater treatment systems within<br />
the public open space. The location<br />
of stormwater treatment systems was<br />
complementary with the landscape<br />
theme that highlighted the presence<br />
of the stream through the centre of the<br />
development. The bioretention systems<br />
and swales will sustain and protect the<br />
ecological health of Second Ponds Creek,<br />
thereby adding to the value of the stream<br />
and the associated green spaces that<br />
attract residents to the area.<br />
<strong>Book</strong> 3 | CASE STUDIES 19
Water Sensitive Urban Design<br />
4 | <strong>WSUD</strong> in the Implementation Phase - Prince Henry<br />
Bioswale integrated into public space | Prince Henry<br />
Prince Henry is a<br />
medium density<br />
development with<br />
approximately<br />
900 dwellings to<br />
be provided on<br />
the 34 hectare<br />
developable area.<br />
The Prince Henry development at Little<br />
Bay is a residential development in the<br />
eastern suburbs of Sydney. The total site<br />
area is approximately 84 hectares of which<br />
34 hectares is being redeveloped into a<br />
mix of residential and community uses.<br />
The remainder of the site is occupied<br />
by the Coast Golf Course and Eastern<br />
Suburbs Banksia Scrub conservation area.<br />
Prince Henry is a medium density<br />
development with approximately 900<br />
dwellings to be provided on the 34 hectare<br />
developable area. The dwellings include:<br />
••<br />
Apartment buildings, from 2 to 6 stories<br />
high, which provide 641 dwellings<br />
••<br />
120 single dwellings including detached<br />
dwellings, courtyard houses and<br />
terraces.<br />
••<br />
114 apartments for over 55’s<br />
••<br />
A 119-person aged care facility<br />
There are also a number of community<br />
buildings, including a community centre,<br />
chapel and small scale commercial and<br />
retail space.<br />
The site is of Aboriginal and European<br />
heritage significance. The development<br />
was formerly the site of the first public<br />
hospital administered by the government<br />
and contains significant heritage items,<br />
including 19 buildings which are listed on<br />
the NSW State Heritage Register. The site<br />
also comprises remnant bushland of state<br />
and national significance, a geological<br />
site, wetlands, ponds, a creek and Little<br />
Bay beach.<br />
Importantly for the <strong>WSUD</strong> strategy, the site<br />
has an existing golf course downstream<br />
of the development. The golf course<br />
currently uses one main storage pond and<br />
another secondary pond to irrigate the<br />
golf course when there is sufficient water<br />
available. The golf course is currently<br />
undergoing an expansion of its irrigation<br />
system whereby its irrigation demand will<br />
double.<br />
20 <strong>Book</strong> 3 | CASE STUDIES
Water Sensitive Urban Design<br />
4.1 <strong>WSUD</strong> Objectives<br />
The <strong>WSUD</strong> objectives for the site<br />
were developed during the<br />
Masterplanning process in 2003 and<br />
are outlined in Table 3.<br />
These targets were complemented by the<br />
following objectives:<br />
••<br />
Promotion of stormwater reuse to<br />
reduce the demand on potable water<br />
supply<br />
••<br />
Ensure that no existing stormwater<br />
reuse is disadvantaged because of the<br />
development<br />
••<br />
Restoration of the riparian zones and<br />
creek lines of two waterways on site,<br />
identified as the Central and Southern<br />
Watercourses.<br />
••<br />
Use less water for landscaping through<br />
careful design and selection of plants<br />
and irrigation methods suitable to the<br />
soil type and location<br />
Table 3 | Landcom’s <strong>WSUD</strong> Targets for Prince Henry<br />
Objective<br />
Water Conservation<br />
Performance Measure and Target<br />
(a) Combination of water efficiency and reuse options – 40% reduction<br />
on base case.<br />
(a) 45% reduction in the mean annual load of Total Nitrogen (TN).<br />
Pollution Control<br />
(b) 45% reduction in the mean annual load of Total Phosphorus (TP).<br />
(c) 80% reduction in the mean annual load of Total Suspended Solids<br />
(TSS).<br />
Heritage, flora<br />
and fauna, and<br />
the surrounding<br />
land uses were the<br />
most important<br />
constraints on the<br />
development.<br />
4.2 Constraints to <strong>WSUD</strong><br />
There are a number of significant<br />
constraints for the re-development of<br />
Prince Henry Hospital in general and<br />
a number of minor constraints on the<br />
<strong>WSUD</strong> strategy. Heritage, flora and<br />
fauna, and the surrounding land uses<br />
were the most important constraints on<br />
the development. The heritage status of<br />
the channel in the Southern Watercourse<br />
in particular dictates that the Southern<br />
Watercourse could not be restored to a<br />
natural waterway as in the original <strong>WSUD</strong><br />
strategy. The heritage road infrastructure<br />
has had important implications for the<br />
location and the design of the storage<br />
ponds.<br />
The site also has important bushland,<br />
archaeological remains and an important<br />
geological site. The bushland includes<br />
a significant stand of Eastern Suburbs<br />
Banksia Scrub, an endangered ecological<br />
community. The archaeological remains<br />
on the site include both Aboriginal<br />
and European uses. These constraints<br />
have had important implications for the<br />
location and design of the stormwater<br />
quality treatment devices.<br />
The existing and surrounding land<br />
use is also a significant constraint on<br />
the development. A buffer is required<br />
between the golf course and the<br />
residential development for safety<br />
reasons. The existing waterways and their<br />
riparian zones are currently situated on the<br />
golf course and have therefore provided<br />
significant constraints on the waterway<br />
restoration and riparian zones.<br />
The site’s significant heritage value<br />
creates a unique opportunity to blend<br />
<strong>WSUD</strong> elements within a heritage garden<br />
context. The material selection and<br />
design, species selection and landscaping<br />
design can conform to the heritage<br />
requirements.<br />
<strong>Book</strong> 3 | CASE STUDIES 21
Water Sensitive Urban Design<br />
Wetland | Prince Henry<br />
4.3 Opportunities for <strong>WSUD</strong><br />
A better outcome<br />
for the catchment<br />
could be achieved<br />
by maximising<br />
the harvesting<br />
of stormwater<br />
runoff from the<br />
development into<br />
the existing golf<br />
course storage.<br />
The <strong>WSUD</strong> strategy for the site has three<br />
major components, namely:<br />
••<br />
Water quality treatment<br />
••<br />
Water conservation and reuse strategy<br />
••<br />
Riparian restoration<br />
The key focus in the <strong>WSUD</strong> strategy for the<br />
site was to ensure that for optimal <strong>WSUD</strong><br />
outcomes a whole of catchment approach<br />
was undertaken.<br />
4.3.1 Water conservation and reuse<br />
The second component of the <strong>WSUD</strong><br />
strategy was a water conservation and<br />
reuse strategy. The reuse strategy was<br />
developed around stormwater harvesting<br />
and reuse.<br />
The original strategy recommended that<br />
the most optimal water conservation<br />
outcomes for the catchment as a whole.<br />
The additional demand of the open<br />
space watering in the development was<br />
small (21 megalitres(ML)/yr) compared<br />
to the demand of the golf course (125<br />
ML/yr). Water balance modelling for the<br />
development and the golf course showed<br />
that large scale harvesting of rainwater<br />
or stormwater within the development<br />
would reduce the effectiveness of<br />
existing stormwater reuse at the golf<br />
course. Only minor decreases in potable<br />
water consumption would occur overall,<br />
as the savings in potable water for the<br />
development would be offset by the<br />
increased potable water usage by the<br />
golf course. Thus rainwater tanks for<br />
the development were not an optimal<br />
investment in infrastructure.<br />
A better outcome for the catchment<br />
could be achieved by maximising the<br />
harvesting of stormwater runoff from the<br />
development into the existing golf course<br />
storages, where it would improve the<br />
effectiveness of the existing reuse system.<br />
This would mean avoiding rainwater tanks<br />
within the development, and utilising the<br />
existing storages and infrastructure that<br />
had been developed by the golf course<br />
4.3.2 Water quality treatment<br />
To meet the objective of best practice<br />
stormwater treatment a water quality<br />
treatment strategy was developed for the<br />
site. The water quality treatment strategy<br />
included a treatment train to ensure that<br />
any stormwater discharging from the<br />
development site met the best practice<br />
objectives.<br />
22 <strong>Book</strong> 3 | CASE STUDIES
Water Sensitive Urban Design<br />
Bioswale | Prince Henry<br />
The stormwater treatment train was<br />
developed to meet the suspended<br />
solids, phosphorus and nitrogen load<br />
reduction targets, as well as reductions<br />
in heavy metals, hydrocarbons and gross<br />
pollutants. The treatment train included:<br />
••<br />
Sediment Control Pits on individual<br />
properties. The development is located<br />
on sandy soils which are susceptible<br />
to high shock loads of wind blown<br />
sediment and erosion by surface water<br />
runoff. The sediment control pits are<br />
effectively small sediment basins and<br />
are an important first barrier in reducing<br />
the loads of coarse sediment from the<br />
private lots.<br />
••<br />
Gross Pollutant Traps installed at the<br />
inlet to the bioretention systems to<br />
prevent the deposition of litter into<br />
these systems.<br />
••<br />
Buffer strips which separate the<br />
impervious surfaces and the drainage<br />
system. The buffer strips filter sediments<br />
and coarse pollutants entrained in the<br />
runoff. Buffer strips are also useful in<br />
providing a detention role to reduce<br />
peak flows of small stormwater events.<br />
••<br />
Bioretention Systems incorporated into<br />
the public open space areas, including<br />
parks and the buffer zone between<br />
the golf course and the development.<br />
Stormwater is treated via infiltration<br />
though soil media in the base of these<br />
bioretention systems and conveyed<br />
downstream via perforated pipes.<br />
High flows are retarded within each of<br />
these systems as a result of the surface<br />
storages provided in these systems.<br />
••<br />
Heavily vegetated swale system to<br />
convey the water from the development<br />
to the golf course. This swale system<br />
would also involve restoration of the<br />
waterways and the original concept<br />
included replacement of the current<br />
open brick channel in the Southern<br />
Watercourse with a naturalised<br />
waterway to improve the waterway’s<br />
ecological and aesthetic value.<br />
<strong>Book</strong> 3 | CASE STUDIES 23
Water Sensitive Urban Design<br />
Figure 10 - Swale bioretention system<br />
Figure 11 - Bioretention basin including detention storage<br />
4.4 Integration of <strong>WSUD</strong><br />
into the development<br />
During the Development Application<br />
(DA) and Construction phases of the<br />
development various modifications to the<br />
<strong>WSUD</strong> strategy were made. The changes<br />
to the strategy occurred to meet the needs<br />
and requirements of Landcom, Council, the<br />
project design team, State Government<br />
Departments, and the golf course.<br />
A number of relatively minor modifications<br />
were made to the designs of the stormwater<br />
quality strategy. These changes included:<br />
••<br />
Provision of additional bioretention<br />
systems due to the changes in the<br />
development land uses and provision<br />
of additional single dwellings.<br />
••<br />
Modifications to the bioretention<br />
system in the northwest of the site<br />
to provide for stormwater storage<br />
detention. This meant that the<br />
bioretention system was much deeper<br />
than originally intended and changes<br />
to the batter slopes and shape of the<br />
bioretention were required.<br />
••<br />
Minor modifications of the bioretention<br />
shape and format to conform with the<br />
competing needs of the buffer zone<br />
between the development and the golf<br />
course.<br />
Some images of completed bioretention<br />
systems are shown in Figures 10 and 11.<br />
The full intent of the stormwater quality<br />
strategy has been incorporated into the<br />
development during its implementation,<br />
despite the minor modifications.<br />
This is not the case with the stormwater<br />
harvesting and reuse strategy. The original<br />
strategy has been modified substantially<br />
and in the process the full intent of the<br />
strategy has not been met. Council<br />
were unable to waive their mandatory<br />
rainwater tank policy for single dwellings,<br />
but exempted apartment dwellings from<br />
mandatory rainwater harvesting.<br />
Furthermore the original strategy outlined<br />
sharing of the increased stormwater<br />
resource between the development<br />
and the golf course as the optimal<br />
water conservation outcome. However<br />
in negotiations between Council and<br />
Landcom it was agreed that the public<br />
open space at the development required<br />
its own separate high reliability storage<br />
pond. This would be built on the golf<br />
course and integrated into the golf course<br />
design as an added playing feature of<br />
the course. The Prince Henry dedicated<br />
24 <strong>Book</strong> 3 | CASE STUDIES
Water Sensitive Urban Design<br />
Golf course stormwater storage | Prince Henry<br />
storage pond would be upstream of<br />
the main storage pond of the Coast<br />
Golf Course. This meant that the golf<br />
course would have reduced stormwater<br />
flows to its storage ponds. While the<br />
additional storage increased the amount<br />
of stormwater that could be harvested,<br />
the harvested stormwater would not be<br />
used optimally between the two users<br />
as water would not be shared between<br />
the two users. Finally as compensation<br />
to the golf course Landcom agreed to<br />
construct an additional storage pond for<br />
the golf course. This storage pond had<br />
minimal catchment and was constructed<br />
based on observational evidence from<br />
the golf course maintenance staff that it<br />
was at the interception point for shallow<br />
groundwater flows. The success of this<br />
storage pond will depend predominantly<br />
on its use as an offline storage to pump<br />
water from the main storage pond after<br />
rainfall events.<br />
The Central Watercourse restoration<br />
has been completed in keeping with the<br />
original intent of the <strong>WSUD</strong> strategy.<br />
Rock weirs were used in the channel and<br />
riparian plantings were established on the<br />
banks.<br />
The Southern Watercourse restoration<br />
has been significantly modified from<br />
the original design intent. The bricklined<br />
drainage channel is considered to<br />
have significant heritage value due to<br />
its visibility, condition and age. Thus the<br />
waterway could not be naturalised.<br />
<strong>Book</strong> 3 | CASE STUDIES 25
Water Sensitive Urban Design<br />
4.5 <strong>WSUD</strong> Outcomes<br />
<strong>WSUD</strong> was also<br />
incorporated into<br />
the design of open<br />
spaces.<br />
4.5.1 Water quality treatment<br />
Water quality treatment including gross<br />
pollutant traps, bioretention systems and<br />
buffer strips was modelled in MUSIC. The<br />
modelling showed that the <strong>WSUD</strong> strategy<br />
will meet the pollutant load reduction<br />
targets of 80% of total suspended solids,<br />
45% of total phosphorus and 45% of<br />
total nitrogen for the three watercourses<br />
draining to the east towards the golf<br />
course and Little Bay. A small area which<br />
drains to the west will have treatment that<br />
meets phosphorus and nitrogen targets<br />
but suspended solids reduction will only<br />
be around 65%.<br />
4.5.2 Water conservation and reuse<br />
The dwellings within the development will<br />
achieve a minimum of 40% reduction in<br />
mains water use compared to a benchmark<br />
dwelling in the same area. The reduction<br />
for apartment buildings with more than<br />
30 apartments will achieve a minimum of<br />
60% reduction in mains water use. These<br />
reductions will be achieved through the<br />
use of demand management measures<br />
and water reuse.<br />
The demand management measures for<br />
all dwellings include:<br />
••<br />
Water efficient 3-star fittings for<br />
showers and taps, and 6/3L dual flush<br />
toilets.<br />
••<br />
Eco-packages for new residents where<br />
information and discounts will be<br />
offered on the purchase of efficient<br />
appliances such as washing machines<br />
and dishwashers.<br />
••<br />
Water efficient and drought tolerant<br />
species for 50% of the soft landscape<br />
areas<br />
In addition, all single dwellings will have<br />
rainwater tanks - 2kL rainwater tanks for<br />
smaller dwellings and 3kL tanks for larger<br />
dwellings – the stored rainwater used<br />
for toilet flushing and private landscape<br />
irrigation.<br />
As rainwater harvesting was not part<br />
of the <strong>WSUD</strong> strategy for multi-unit<br />
buildings, multi-unit buildings with more<br />
than 30 apartments (i.e. 10 buildings<br />
with 472 apartments in total) incorporate<br />
greywater treatment within the building.<br />
The greywater will be used for toilet<br />
flushing, private landscape irrigation and<br />
car wash bays.<br />
<strong>WSUD</strong> was also incorporated into the<br />
design of open spaces. There are three<br />
major parks within the development, all<br />
of which will receive 95% of their water<br />
demands from harvested stormwater. The<br />
open space will also incorporate the best<br />
designs in irrigation technology including<br />
automatic irrigation systems, with in built<br />
rain and wind gauges to control irrigation<br />
timing. The open space will also have<br />
drip irrigation in the garden beds and<br />
for the trees. Turf within the parks will be<br />
irrigated by pop up sprinklers. The parks<br />
also reduce their demand by having areas<br />
of native plantings within the landscaped<br />
areas. The ability to use drought tolerant<br />
species has been limited by the need for<br />
the landscape to reflect the European<br />
heritage of the buildings with high water<br />
use plantings, including large areas of turf<br />
around heritage buildings and the central<br />
park.<br />
26 <strong>Book</strong> 3 | CASE STUDIES
Water Sensitive Urban Design<br />
Prince Henry Hospital <strong>WSUD</strong> Opportunities<br />
Integration of <strong>WSUD</strong> measures into<br />
public open space<br />
Proposed bioretention systems can<br />
be incorporated in public open space<br />
in the proposed development, which<br />
includes three major parks<br />
Council rainwater tank policy<br />
The local Council’s rainwater tank<br />
policy requires all new dwellings to<br />
include rainwater tanks. This will be<br />
applied to proposed single dwellings<br />
Neighbouring golf course<br />
The neighbouring golf course uses<br />
significant amounts of water for<br />
irrigation. Stormwater storage for the<br />
site will still be located on the golf<br />
course, where it will be a feature<br />
Chifley<br />
Little Bay<br />
Anzac Pde<br />
Little Bay<br />
Total Developable Area<br />
34.43 HA<br />
The Coast<br />
Golf Course<br />
St Michaels<br />
Golf Course<br />
Irrigation strategy<br />
Three parks which require irrigation will<br />
utilise treated stormwater. Wind and<br />
rain gauges will be used to control an<br />
automated irrigation system so that the<br />
use of water is optimised. Low-water use<br />
species will be used where appropriate<br />
Sandy soils<br />
The coastal location<br />
means that sediment<br />
loads tend to be high.<br />
Sediment control pits<br />
on individual properties<br />
will address this issue<br />
Water efficiency in<br />
dwellings<br />
Residents will be<br />
encouraged to use<br />
efficient appliances and<br />
efficient fittings will be<br />
installed<br />
Waterway<br />
rehabilitation<br />
Existing modified<br />
channels on the site<br />
will be restored as far<br />
as possible to achieve<br />
higher ecosystem<br />
values<br />
Source - Google Earth<br />
<strong>Book</strong> 3 | CASE STUDIES 27
Water Sensitive Urban Design<br />
5 | Operation and Maintenance of <strong>WSUD</strong><br />
treatment measures - Victoria Park<br />
Figure 12 - Aerial photograph of Victoria Park site in Zetland, Sydney.<br />
The site boundary is indicated by the dotted line. Image: Waltcorp<br />
The site was<br />
formerly known as<br />
Waterloo swamp,<br />
which by 1908 had<br />
been drained and<br />
converted into a<br />
race track.<br />
This case study reports on the operation<br />
and maintenance of the <strong>WSUD</strong> treatment<br />
measures at Victoria Park that have been in<br />
place for over eight years. It highlights the<br />
innovative approach taken to overcome<br />
many of the site constraints, and the<br />
longevity of the treatment devices.<br />
Victoria Park represents one of the earliest<br />
and most durable applications of <strong>WSUD</strong><br />
in Sydney. The Victoria Park development<br />
is in Zetland, 4 km southeast of the Sydney<br />
CBD (Figure 12). The total site area is 25.2<br />
ha. Approximately 1800 dwellings will be<br />
built consisting of 92% apartments and 8%<br />
terrace housing for a population of 3000<br />
residents. Public open space occupies<br />
15% or 3.7 ha of the site, commercial, retail<br />
and community uses occupy 4.3 ha.<br />
The site was formerly known as Waterloo<br />
swamp, which by 1908 had been drained<br />
and converted into a race track. After<br />
World War II the racetrack became an<br />
industrial site and was used for a car<br />
manufacturing plant for the British motor<br />
Co. From 1974 to 1997 it was then used as<br />
a naval supply centre.<br />
28 <strong>Book</strong> 3 | CASE STUDIES
Water Sensitive Urban Design<br />
Victoria Park<br />
5.1 <strong>WSUD</strong> Objectives<br />
To reduce dependency on potable water<br />
supplies, opportunities were identified for<br />
water conservation and re-use. The <strong>WSUD</strong><br />
strategy for the site also aimed to protect<br />
the downstream ecosystems by:<br />
••<br />
Removing pollutants from urban runoff<br />
and,<br />
••<br />
Controlling the flow of water running<br />
off the site.<br />
As the site was planned prior to the<br />
establishment of Landcom’s <strong>WSUD</strong><br />
strategy, specific targets were not<br />
established for the site.<br />
5.2 Constraints to <strong>WSUD</strong><br />
This low-lying inner-city site had many<br />
constraints to development:<br />
••<br />
The redevelopment of this former<br />
industrial site required extensive land<br />
remediation.<br />
••<br />
The developable area was tightly<br />
constrained by existing property<br />
boundaries and infrastructure.<br />
••<br />
The groundwater aquifer is also quite<br />
shallow sitting only 1 – 2.8 m below the<br />
ground surface. The aquifer itself is<br />
complex, made up of permeable strata<br />
separated by impermeable layers of<br />
peat.<br />
••<br />
The large areas of site set aside for<br />
public open space required a reliable<br />
source of irrigation water to be<br />
maintained as green spaces.<br />
••<br />
Flood control is difficult in flat sites<br />
because pipes on flat grades need to<br />
be larger to accommodate the same<br />
volume as smaller pipes on steeper<br />
grades. Victoria Park site already<br />
receives runoff from Kensington<br />
upstream and to accommodate extra<br />
urban runoff from the Victoria Park site<br />
in stormwater drainage would need to<br />
be upgraded.<br />
••<br />
The Victoria Park site was also<br />
required to detain large flows from the<br />
surrounding catchments making some<br />
of the site flood prone.<br />
<strong>Book</strong> 3 | CASE STUDIES 29
Water Sensitive Urban Design<br />
Figure 13 - Bioretention swales have been buillt in the road<br />
median strip to remove pollutants from urban<br />
runoff<br />
5.3 Opportunities<br />
for <strong>WSUD</strong><br />
Figure 14 - Water is directed to the bioretention<br />
swale from an inverted road camber and<br />
through kerb cuts<br />
Space for water<br />
conveyance swales<br />
was made available<br />
along the forefront<br />
of the residential<br />
towers on the site.<br />
Although development of the site is<br />
constrained in many aspects, the location<br />
of Victoria Park in a low landscape position<br />
surrounded by high density development<br />
also offers many opportunities:<br />
••<br />
Flood prone areas are unsuitable for<br />
buildings, but the available space was<br />
used for the multiple purposes of water<br />
conveyance, water treatment, and flood<br />
detention.<br />
••<br />
Flood prone areas also suitable for use<br />
as public open space, as well watered,<br />
flat open spaces provide ideal locations<br />
for urban parks.<br />
••<br />
Harvesting water is easier for sites<br />
located in low-lying areas of catchments<br />
and was desirable that this potential be<br />
realised. Water harvesting can be used<br />
to meet the irrigation requirements of<br />
the surrounding public open space.<br />
••<br />
Although the shallow aquifer constrains<br />
building through areas of the site, this<br />
aquifer provides both a source of water<br />
for the site as bore water, and as a<br />
storage facility that can be harnessed<br />
through groundwater aquifer storage<br />
and recovery.<br />
5.3.1 Overcoming site constraints<br />
The constraints imposed by the undersized<br />
stormwater infrastructure were overcome<br />
by conveying water along the ground<br />
surface. Space for water conveyance<br />
swales was made available along the<br />
forefront of the residential towers on the<br />
site. Tall buildings require a wider set back<br />
from the road to create the symmetry of<br />
space that makes aesthetic urban and<br />
landscape design. Bioretention swales<br />
were built on these open spaces and used<br />
to convey stormwater run-off.<br />
30 <strong>Book</strong> 3 | CASE STUDIES
Water Sensitive Urban Design<br />
Figure 15 - Joynton Park: Treated urban runoff from the<br />
bioretention swales is reused in the water stairs<br />
Figure 16 - Public open spaces also function<br />
as flood detention basins<br />
The groundwater<br />
aquifer is<br />
replenished with<br />
stormwater run-off<br />
from the detention<br />
basins.<br />
5.4 Integration of <strong>WSUD</strong><br />
into the development<br />
5.4.1 Water quality<br />
Bioretention swales were built into the<br />
central median strips of the east-west<br />
roads (Figure 13). The camber of the<br />
road was graded towards the central<br />
median strip rather than towards the road<br />
image, to direct water to the bioretention<br />
swale (Figure 14). Pollutants in road<br />
runoff removed as water flows through<br />
bioretention swales and the filter media.<br />
Perforated pipes collect treated water<br />
and discharge it to a water storage tank.<br />
This water is used in two substantial water<br />
features in Joynton Park - the water stairs<br />
(Figure 15).<br />
5.4.3 Water conservation and reuse<br />
Irrigation of the public open spaces is<br />
sourced from the groundwater aquifer<br />
(Figure 17). The groundwater aquifer is in<br />
turn replenished with stormwater run-off<br />
from the detention basins. The vegetation<br />
used in the constructed wetlands and<br />
bioretention swales have been selected<br />
for drought and flood tolerance and<br />
require no irrigation.<br />
5.4.2 Water quantity<br />
To slow the rate of runoff from the site,<br />
and to encourage water infiltration to<br />
replenish the groundwater aquifer - the<br />
public open spaces within the site also<br />
function as stormwater detention basins<br />
(Figure 16). Overland flow is resulting<br />
from major storm events in excess of the<br />
one in 20 year annual recurrence interval<br />
(ARI) are conveyed by the road surfaces.<br />
To facilitate this, the roads throughout the<br />
site were carefully graded to direct runoff<br />
appropriately and to avoid ponding.<br />
Figure 17 - All water for irrigation is sourced from<br />
the groundwater aquifer below the<br />
surface<br />
<strong>Book</strong> 3 | CASE STUDIES 31
Water Sensitive Urban Design<br />
Figure 18 - Tufted species maintain their biomass through vigorous vegetative growth<br />
5.5 <strong>WSUD</strong> Implementation<br />
and Maintenance<br />
The bioretention<br />
swales have<br />
functioned as<br />
designed through<br />
all rainfall events for<br />
several years.<br />
5.5.1 Establishment<br />
The establishment vegetation in the<br />
bioretention swales was very successful.<br />
The following vegetation was planted:<br />
••<br />
Eucalyptus citriodora (Lemon-scented<br />
Gum Tree),<br />
••<br />
Isolepis nodosa (Nobby Club-rush, a<br />
tufted species of sedge)<br />
••<br />
Lomandra longifolia (Matrush, a tufted<br />
species of sedge)<br />
••<br />
Poa spp. (Tussock Grass)<br />
There was very little mortality during the<br />
establishment phase for all grasses and<br />
sedges. There was no mortality of the<br />
trees. Plants were irrigated throughout<br />
their establishment. The death of some<br />
grasses was associated with the failure of<br />
the irrigation system that coincided with<br />
a six-week hot, dry spell. After six years<br />
the vegetation is now considered to be<br />
self-sufficient for water requirements.<br />
The biomass of the tufted species is<br />
maintained through vegetative regrowth<br />
(Figure 18). The trees of the bioretention<br />
swales have grown as tall or taller than the<br />
nearby street trees of the same species,<br />
and appear to be an equally good health<br />
(Figure 19). Water stress on the plant<br />
is partially relieved by maintaining an<br />
adequate surface mulch of bark chips to<br />
retain soil moisture (visible in Figure 14).<br />
The bioretention swales have functioned<br />
as designed through all rainfall events for<br />
several years. The media has retained<br />
its permeability and continues to allow<br />
water to drain through the bioretention<br />
swales appropriately. There have been no<br />
instances of water remaining ponded for<br />
longer than the design period (less than<br />
24 hours). The swale plants have survived<br />
all the wet periods, usually responding to<br />
the wet conditions with a flush of growth.<br />
The woodchip mulch of the swales has<br />
also been stable; there were no instances<br />
of the mulch migrating from the swales to<br />
the street during periods of high rainfall<br />
(Figure 20).<br />
The experience at Victoria Park has<br />
demonstrated that <strong>WSUD</strong> elements can<br />
be built with few ongoing maintenance<br />
requirements, and can be maintained at<br />
a cost that is comparable to many public<br />
landscapes.<br />
32 <strong>Book</strong> 3 | CASE STUDIES
Water Sensitive Urban Design<br />
Figure 19 - The trees of the bioretention<br />
swales (left) have grown as tall<br />
as the street trees (right) and<br />
are in good health<br />
Figure 20 - The woodchip mulch is stable<br />
even during ponding from<br />
urban runoff<br />
The cost of<br />
maintaining the<br />
<strong>WSUD</strong> features<br />
is comparable<br />
to landscaping<br />
costs for standard<br />
landscape features<br />
such as swales and<br />
street trees.<br />
5.2.2 Maintenance<br />
bioretention swales<br />
Maintenance of the trees in the<br />
bioretention swales involves the practices<br />
normal for street trees; branches are<br />
trimmed and leaves and bark must be<br />
swept. Leaves and bark generated by the<br />
swale trees is put back into the swale to<br />
act as mulch. The grasses and sedges<br />
are periodically trimmed. These plants<br />
die back during dry periods and the dead<br />
material is removed to reduce the risk that<br />
may pose as a fire hazard.<br />
The maintenance of the vegetated<br />
<strong>WSUD</strong> features has been integrated into<br />
the landscape maintenance program<br />
for all of the public open spaces of the<br />
Victoria Park site. The cost of maintaining<br />
the <strong>WSUD</strong> features is comparable to<br />
landscaping costs for standard landscape<br />
features such as swales and street trees.<br />
The maintenance does not require any<br />
specialised equipment.<br />
Initially, the contractors were concerned<br />
about maintaining swales in the<br />
high-density urban environment. Their<br />
concerns centred on the accumulation of<br />
litter and the possibility of needle stick<br />
injuries from unseen debris hidden in<br />
the tussocks of the grasses and sedges.<br />
Fortunately these concerns have not been<br />
realised. Very little litter has accumulated<br />
in the swales and no needles have<br />
been found yet. The low maintenance<br />
requirements of the swales is attributed<br />
to:<br />
••<br />
The use of hardy plant species<br />
appropriate to the growth environment,<br />
resulting in good vegetation growth<br />
(Figure 18)<br />
••<br />
The high value that the residents place<br />
on the bioretention swales, resulting in<br />
lower litter loads and few instances of<br />
plants disturbances and trampling<br />
<strong>Book</strong> 3 | CASE STUDIES 33
Water Sensitive Urban Design<br />
Figure 21 - The water stairs reuse harvested stormwater<br />
The Victoria Park<br />
development<br />
dispels fears<br />
that bioretention<br />
systems may<br />
create onerous<br />
maintenance<br />
obligations for the<br />
land manager.<br />
5.6 <strong>WSUD</strong> Outcomes<br />
Only small volumes of water have been<br />
available for reuse. The stormwater from<br />
the swales is captured and stored for reuse<br />
in the water stairs - two prominent features<br />
of Joynton Park (Figure 21). However, a<br />
high proportion of runoff is held within the<br />
filter media and evaporated or transpired<br />
by the vegetation. Consequently, treated<br />
stormwater only becomes available for<br />
reuse after sustained rain or large rainfall<br />
events.<br />
5.7 Conclusions<br />
<strong>WSUD</strong> is best created by forming site<br />
specific solutions that respond to the<br />
local environment. <strong>WSUD</strong> at Victoria<br />
Park was achieved by working around<br />
the site constraints and making the<br />
most of the opportunities that the site<br />
presented. The development illustrates<br />
that by working with the site topography<br />
and environment, well built bioretention<br />
swales can filter urban runoff and help<br />
protect downstream aquatic ecosystems<br />
in addition to creating green spaces of<br />
long-lasting amenity. The success of<br />
these swales was due to the selection<br />
of appropriate hardy plants and the<br />
creation of landscape elements highly<br />
valued by the residents. The Victoria<br />
Park development dispels fears that<br />
bioretention systems may create onerous<br />
maintenance obligations for the land<br />
manager.<br />
34 <strong>Book</strong> 3 | CASE STUDIES
Water Sensitive Urban Design<br />
<strong>Book</strong> 3 | CASE STUDIES 35
Level 2, 330 Church Street<br />
Parramatta NSW 2150<br />
PO Box 237 Parramatta NSW 2124<br />
DX 28448 Parramatta<br />
Telephone 61 2 9841 8600<br />
Facsimile 61 2 9841 8688<br />
Printed May 2009 on recycled paper.