Blackburn Wastewater Treatment Plant Upgrade Study
Blackburn Wastewater Treatment Plant Upgrade Study
Blackburn Wastewater Treatment Plant Upgrade Study
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BLACKBURN WASTEWATER<br />
TREATMENT PLANT UPGRADE STUDY<br />
Prepared for:<br />
The City of Prince George<br />
1100 Patricia Boulerard<br />
Prince George, B.C. V2L 3V9<br />
Prepared by:<br />
Reid Crotitber & Partners Ltd.<br />
Consulting Engineering Worldwide<br />
300 - 4170 StiU Creek Drive<br />
Burnnby, BC<br />
V5C 6C6<br />
Phone: (604) 298-6181<br />
Far: (604) 294-8597<br />
November, 1999<br />
Projwt No. 34918-00 (3)
<strong>Blackburn</strong> <strong>Wastewater</strong> <strong>Treatment</strong> <strong>Plant</strong> <strong>Upgrade</strong> <strong>Study</strong><br />
SECTION<br />
Table of Contents<br />
TITLE PAGE NO .<br />
1 STUDY BACKGROUND AND OBJECTIVES ................................................... 1-1<br />
Introduction .................................................................................................... 1-1<br />
Blackbum WWTP .......................................................................................... 1-2<br />
Lansdowne Road WWTP .............................................................................. 1-3<br />
Collection System .......................................................................................... 1-3<br />
<strong>Upgrade</strong> Options ............................................................................................. 1-4<br />
. .<br />
Ammonia Toxmty Issues .................................................. ............................ 1-4<br />
. .<br />
Population and Flow Projechons .................................................................. 1-5<br />
1.7.1 Outline .......................................................................................... 1-5<br />
1.7.2 Design Populations ...................................................................... 1-5<br />
1.7.3 Design <strong>Wastewater</strong> Flows ............................................................ 1-6<br />
............................................................<br />
1.7.4 Design <strong>Wastewater</strong> Loads 1-8<br />
. 1.7.5 Wet Weather Flow Impacts . 1-8<br />
1.7.6 Wet Weather Flows 1-9<br />
......................................................................<br />
Regulatory Background ............................................................................... 1-10<br />
.........................................<br />
1.8.1 Blackbum WWTP Discharge Permit 1-10<br />
1.8.2 Lansdowne Road WWTP Discharge Pennit 1-10<br />
1.8.3 BC Municipal<br />
.<br />
Sewage<br />
.<br />
Regulations ........................................... 1-11<br />
.....................................................................<br />
1.8.4 Ammonia Toxlclty 1-12<br />
2 VI MITGATION MEASURES ..................................................................................... 2-1<br />
2.1 Introduction ................................................................................................. 2-1<br />
2.2 I/I Reduction Plan .......................................................................................... 2-2<br />
2.2.1 Inflow Reduction ......................................................................... 2-2<br />
2.2.2 Infiltration Reduction ................................................................... 2-2<br />
........................................................................<br />
2.3 Rehabilitation Cost Estimates 2-3<br />
3 AUDIT OF EXISTING FACILITIES ......................................................................... 3-1<br />
3.1 Blackbum <strong>Wastewater</strong> <strong>Treatment</strong> <strong>Plant</strong> ....................................................... 3-1<br />
3.1.1 Outline .......................................................................................... 3-1<br />
3.1.2 Preliminary <strong>Treatment</strong> ................................................................. 3-1<br />
3.1.3 Secondary <strong>Treatment</strong> ................................................................... 3-2<br />
3.1.4 Effluent Disposal ......................................................................... 3-2<br />
3.1.5 Sludge <strong>Treatment</strong> ......................................................................... 3-2<br />
.............................................<br />
3.2 Lansdowne Road <strong>Wastewater</strong> <strong>Treatment</strong> <strong>Plant</strong> 3-2
Table of Contents<br />
SECTION TITLE PAGE KO .<br />
3.2.1 Outline .......................................................................................... 3-2<br />
3.2.2 Preliminary <strong>Treatment</strong> ................................................................. 3-3<br />
3.2.3 Primary <strong>Treatment</strong> .................................................................... 3-3<br />
3.2.4 Secondary <strong>Treatment</strong> ................................................................ 3-3<br />
3.2.5 EMuent Disposal ...................................................................... 3-4<br />
3.2.6 Sludge <strong>Treatment</strong> ......................................................................... 3-4<br />
3.3 Operations Staff ............................................................................................. 3-5<br />
3.4 Concjusion .....................................................................................................<br />
3-5<br />
4 WASTEWATER TREATMENT OPTIONS ........................................................... 4-1<br />
Option 1 ......................................................................................................... 4-1<br />
4.1.1 Outline .............. I: .......................................................................... 4-1<br />
4.1.2 Design Information ...................................................................... 4-2<br />
4.1.3 Cost Estimate ............................................................................... 4-3<br />
Option 2 ......................................................................................................... 4-3<br />
4.2.1 Outline .......................................................................................... 4-3<br />
4.2.2 Design Information ...................................................................... 4-4<br />
4.2.3 Cost Estimate ............................................................................... 4-5<br />
Option 3 ......................................................................................................... 4-6<br />
4.3.1 Outline .......................................................................................... 4-6<br />
4.3.2 Design Information ...................................................................... 4-7<br />
4.3.3 Cost Estimate ............................................................................... 4-7<br />
Option 4 ......................................................................................................... 4-8<br />
4.4.1 Outline .......................................................................................... 4-8<br />
4.4.2 Design information ...................................................................... 4-9<br />
4.4.3 Cost Estimate ............................................................................. 4-10<br />
Option 5 ........................................................... ........................................... 4-10<br />
4.5.1 Outline ........................................................................................ 4-10<br />
4.5.2 Design Information .................................................................... 4-12<br />
4.5.3 Cost Estimate ............................................................................. 4-12<br />
Option 6 ....................................................................................................... 4-13<br />
4.6.1 Outline ........................................................................................ 4-13<br />
4.6.2 Design Information .................................................................... 4-14<br />
4.6.3 Cost Estimate ............................................................................. 4-17<br />
Option 7 ....................................................................................................... 4-18<br />
4.7.1 Outline ........................................................................................ 4-18<br />
4.7.2 Design Information .................................................................... 4-19<br />
4.7.3 Cost Estimate ............................................................................. 4-23<br />
Life Cycle Cost Analysis ............................................................................. 4-24<br />
(ii)
Table of Contents<br />
SECTION TITLE PAGE NO .<br />
5 EVALUATION OF OPTIONS ..................................................................................... 5-1<br />
. .<br />
5.1 Decision Cr~ter~a ............................................................................................ 5-1<br />
5.1.1 Introduction .................................................................................. 5-1<br />
. . 5.1.2 Cost Cnter~a ................................................................................. 5-2<br />
. .<br />
5.1.3 Performance Criter~a .................................................................... 5-2<br />
. .<br />
5.1.4 Operational Cntena ...................................................................... 5-3<br />
5.1.5 Environmental and Aesthetic Criteria .......................................... 5-3<br />
5.2 Evaluation Techniques ................................................................................... 54<br />
5.2.1 Introduction ............................................................................... 54<br />
5.2.2 Weighted Analysis of Evaluation Criteria ................................... 5-5<br />
5.2.3 Pair-Wise Comparison ................................................................. 5-5<br />
5.3 Evaluation Results ..............:...........................................................................<br />
5-6<br />
6 RECOMMENDED OPTION ........................................................................................ 6-1<br />
6.1 Introduction .................................................................................................... 6-1<br />
6.2 Reduced Inflow/Infiltration .......................................................................... 6-1<br />
6.3 Existing Downtown Sewerage System .......................................................... 6-2<br />
6.4 Upgrading Plan ............................................................................................... 6-2<br />
6.5 Option 1 Design Information ......................................................................... 6-3<br />
6.6 Project Staging ............................................................................................... 6-4<br />
6.7 Overall Implementation Program ................................................................... 6-5<br />
APPENDIX A ............................ STANTEC CONSULTING LTD . STUDY CONCLUSIONS<br />
APPENDIX B ...................... ESTIMATED CAPITAL AND 25 YEAR LIFE CYCLE COSTS<br />
APPENDIX C ..............................................<br />
DECISION WORKSHOP . OCTOBER 19. 1999<br />
WORKSHOP NOTES<br />
APPENDIX D .............................................. DECISION WORKSHOP - OCTOBER 19, 1999<br />
RANKING/COMPARISON RESULTS<br />
APPENDIX E ...................................... now CALCULATIONS FOR SEWER UPGRADES
SECTION 1<br />
STUDY BACKGROUND AND OBJECTIVES
SECTION 1.0<br />
STUDY BACKGROUND AND OBJECTIVES<br />
1.1 INTRODUCTION<br />
Integral to the continued growth and development of the City of Prince George is a<br />
reliable sewage collection and treatment system that meets current environmental<br />
standards. Over the years, steady development has taken place in the city central areas<br />
and the Nechako area to the north of the city core. Within the <strong>Blackburn</strong> area, which<br />
is located east of the Fraser River in the east sector of the City, development has been<br />
curtailed due to limited water supply to this area. In addition to the water supply<br />
system, irhastructure is in place for sewage collection and treatment. The City of<br />
Prince George is serviced primarily by one main wastewater treatment facility located<br />
on Lansdowne Road. Outlying subdivisions or sewage collection areas such as the<br />
Blackbum area are serviced by small satellite wastewater treatment facilities.<br />
Until recently, there has been a development moratorium in place in the Blackbum<br />
area due to inadequate water supply. The water supply system has now been upgraded<br />
and the moratorium lifted. It is anticipated that the Blackbum area will experience a<br />
healthy population growth rate and the planned population horizon of 5,000 could be<br />
realized in the next 25 years.<br />
With the anticipated growth and development in the Blackbum area, the City now<br />
wishes to consider the most appropriate and economic option for wastewater<br />
collection/treatment, as well as being in compliance with the new Municipal Sewage<br />
Regulations. The issues that drive the evaluation of options are the capacity of the<br />
existing treatment facility to meet effluent quality criteria; and, the high inflow and<br />
infiltration @'I) peak flows into the collection system that impart hydraulic limitations<br />
both at the Mackus Road pumpstation and at the treatment facility. .<br />
Further to the issues related to the existing sewage collection and treatment system and<br />
the anticipated population growth projections for the Blackbum area, the City of<br />
Prince George commissioned Reid Crowther and Partners Ltd. in September 1999, to<br />
prepare a study to evaluate options on how to manage sewage collected within the<br />
<strong>Blackburn</strong> sewerage area. This report presents these f ndings; identifies and evaluates<br />
options using both economic and non-economic criteria; and recommends an<br />
implementation plan.
Section 1.0 -Project Background and Objectives<br />
The overall aim of this study is to develop a long term plan that incorporates the latest<br />
issues regarding the Blackbum collection, pumping and treatment system, and<br />
establishes whether the City should proceed with upgrading the Blackbum wastewater<br />
treatment facility independently or to consolidate Blackbum sewage flows into the<br />
Lansdowne Road WWTP via connecting purnpinglpipeline infrastructure. Under both<br />
scenarios implementation of appropriate VI reduction measures is required.<br />
A brief summary of the existing wastewater treatment facilities and related issues is<br />
presented in the following sections.<br />
1.2 BLACKBURN WWTP<br />
Construction of the Blackbum wasiewater treatment facility commenced early in 1976<br />
and the facility was commissioned in late 1976 to service a population of 2,500. The<br />
existing facility is comprised of a bar screen, and aerated primary and secondary<br />
lagoons.<br />
The effluent discharge requirements are for BOD5 5 45 mgL, TSS 5 60 mg/L plus a<br />
fecal colifom limit. Any upgrade to the plant would be based on the new Municipal<br />
Sewage Regulations. Presently the Department of Fisheries and Oceans are requesting<br />
an ammonia toxicity limit, which to date has not been required by the Ministry of<br />
Environment, Lands and Parks. This situation may change in the future.<br />
The facility is presently at both its hydraulic and organic design capacities.<br />
Winterlspring thaw conditions and heavy rains contribute high inflow/infiltration peak<br />
wet weather flows (PWWF). Effluent quality is also impacted during the spring to<br />
summer transition as the primary and secondary lagoons warm up. Lagoon
Section 1.0 - Proj~t Background and Objectives<br />
temperatures in the winter drop to between 0°C and 5"C, and in the summer they can<br />
exceed 20°C.<br />
The lagoon aeration equipment is also reaching the end of its design life. The facility<br />
upgrade will be for a population of 5,000, which is equivalent to a 25 year design<br />
horizon.<br />
1.3 LANSDOWNE ROAD WWTP<br />
The Lansdowne Road wastewater treatment facility was recently upgraded to a Year<br />
2026 design horizon with a contributing population of 115,000 and average dry<br />
weather flow of 44.5 Mud. The current contributing population is less than 90,000.<br />
As a result there is adequate design capacity at the plant should the decision be made<br />
to transfer raw sewage flows fiorn the Blackbum sewerage area to Lansdowne Road<br />
WWTP. All potential impacts of transporting flows to the Lansdowne Road WWTP<br />
would, however, need to be considered in detail during this study to ensure viability of<br />
such an option.<br />
1.4 COLLECTION SYSTEM<br />
Most of the construction work on the sewage collection system for the <strong>Blackburn</strong><br />
sewerage area was completed in 1976, and consists of 25 kilometers of both gravity<br />
and forcemain sewers. The pipe network is mostly PVC pipe with some of the larger<br />
diameter pipes being concrete. Soil type in the area is mainly clay in nature with the<br />
pipes laid in sand bedding backfilled with native soils.
Section 1.0 -Project Background and Objectives<br />
The main snowfall in the area occurs from November to April. During winter/spring<br />
thaw conditions, the collection system experiences high IeveIs of UI, raising flow<br />
levels above the capacity of the treatment plant. To determine the nature of the Vi<br />
problem, the City completed a study in June, 1999 to assess the condition of the<br />
pipework, manholes and connections. Manholes that are located in lowlying areas<br />
have been found to be the main contributor of inflow. Snowmelt and water that ponds<br />
around these manholes enters through manhole lids and cracks or deficiencies in the<br />
manhole itself. The City's rehabilitation program will consider the raising of manhole<br />
rims, sealing of manhole lids and the grouting of inner walls. Elimination of cross<br />
connections and repair of sub-standard connection construction that contributes to L'l<br />
will also be part of the rehabilitation work.<br />
1.5 UPGRADE OPTIONS<br />
The principal objective of this study is to examine all issues concerned with the<br />
<strong>Blackburn</strong> sewerage area in order to determine if the City should proceed with<br />
upgradelexpansion of the existing wastewater treatment facility and the Mackus Road<br />
pumpstation; or, transfer raw sewage flows to and consolidate treatment at the<br />
Lansdowne Road WWTP.<br />
For this study, sewer upgrade and treatment expansion options have been identified.<br />
Assessment of the study options includes an appraisal of both economic and noneconomic<br />
criteria. Cost analyses includes full life cycle costing of both capital and<br />
operating/maintenance costs over the planning horizon time-kame of 25 years.<br />
Frequently, the least capital wst can have the highest long-term life-cycle cost. Noneconomic<br />
criteria include environmental impacts, ease of operation, system flexibility<br />
and pubiic/stakeholder preferences.<br />
1.6 AMMONIA TOXICITY ISSUES<br />
There are uncertainties as to whether the upgraded <strong>Blackburn</strong> wastewater treatment<br />
facility will have ammonia toxicity limits placed on the effluent, \vhich is discharged<br />
to the Fraser River. This study takes into account this eventuality.<br />
Ammonia toxicity can place a wastewater treatment emuent in noncompliance with<br />
Fisheries Act requirements. The requirements of the Act are interpreted to mean that<br />
emuents discharged into an aquatic environment should be non-toxic, as measured in<br />
a static bioassay. The Act does not provide for effluent dilution or dispersion to<br />
mitigate toxicity.
Section k .O - Project Background and Objectives<br />
Ammonia limits for effluents discharged to aquatic environments, as published by US<br />
EPA are based on toxicity considerations. These limits can be used to judge the likely<br />
impact of wastewater treatment plant effluents. The EPA limits are approximately<br />
based on the toxicity of ammonia to relevant water species, modified by a safety<br />
factor. Recent modifications of these criteria have been adopted to reflect the findings<br />
of recent studies. These studies note that cold water toxicity is not as severe as<br />
previously found and winter limits need not be as restrictive since more sensitive<br />
juve~le fish are not present during winter months. This study assesses these<br />
considerations.<br />
1.7 POPULATION AND FLOW PROJECTIONS<br />
1.7.1 Outline<br />
Fundamental to a long-term strategic upgrade plan is a thorough assessment of future<br />
population growth, and hence, changes in anticipated wastewater flows. Projections<br />
need to be evaluated in light of the City's Ifl rehabilitation program, Municipal<br />
Sewage Regulations, the availability of adequate water supply and development plans<br />
for the area. The estimated existing serviced popuiation is 1,800. However, not all of<br />
the serviced population is connected to the domestic sewage collection system. The<br />
estimated population CO~eCted to the collection system is 1,500. It is anticipated that<br />
the population growth in this area will be vigorous with steady growth estimated at<br />
approximately 4 percent per annum.<br />
1.7.2 Design Population<br />
The City's estimate for the year ending 1998 is a serviced population of 1,800.<br />
Population growth in the <strong>Blackburn</strong> area over the past 25 years has been slow, due in<br />
part to limited water supply. Water supply to the area has been upgraded and there is<br />
now sufficient capacity to service a fuH development population of 5,000.<br />
With adequate water supply for the Blackbum area, the projected population growth<br />
rate is estimated to be approximately 4 percent, which is greater than the projected<br />
growth rate for the entire City which is 1 percent. Assuming a growth rate of 4.2<br />
percent, the population will increase from 1,800 to 5,000 in 25 years.<br />
Population projections for the <strong>Blackburn</strong> sewage collection area are presented in Table<br />
1.1.
Section 1.0 -Project Background and Objectives<br />
Tablel.1- <strong>Blackburn</strong> Sewage Collection Area<br />
Population Projection<br />
Design <strong>Wastewater</strong> Flows<br />
The flow criteria used in 1976 for the design of the Blackbum WWTP are:<br />
Population 2,500<br />
Per capita contribution, Lkapfd 375<br />
ADWF. m3/d 945<br />
PWWF, m3/d 4,350<br />
The design flow criteria us4 in 1993 to plan the Lansdowne Road WWTP upgrade<br />
and expansion are:<br />
Population 1 15,000<br />
Per capita contribution. L/ca~/d
Section 1.0 -Project Background and Objectives<br />
PWWF, m3/d 11 5,000<br />
Flow records for 1998 for the Blackbum WWTP provide the following information:<br />
Population 1,800<br />
Per capita contribution (calculated), Ucapld 250<br />
ADWF, m31d 450<br />
PWWF, m3/d 4,500<br />
The ADWF flow records for lackb bum indicate a very low per capita contribution. It<br />
is likely that of the estimated 1,800 population within the Blackbum sewage collection<br />
area, not all are connected to the collection system. If it is assumed that approximately<br />
75 percent of the Blackbum population, which is 1,350, is connected to the system, the<br />
calculated per capita contribution is 335 Ucapld. For this study, the per capita<br />
contributory flow is assumed to be 350 Llcapld, which is 10 percent lower than the<br />
design value used for the Lansdowne WWTP. Because of the more rural setting of the<br />
<strong>Blackburn</strong> area; the probable lower use of dishwashershome garburators; smaller<br />
residence size; and, the fact that the sewage pipework is only 25 years old, a 10<br />
percent decrease in per capita contributory flow from 385 to 350 can be rationalized.<br />
The following design flow conditions are assumed for 111 development in the<br />
<strong>Blackburn</strong> area:<br />
Population 5,000<br />
rn Per capita contribution, LJcapld 350<br />
ADWF, m3ld 1,750<br />
The contribution of flow from the Blackbum sewage collection area at full<br />
development in comparison to the design flow capacity of the Lansdowne Road<br />
WWTP is calculated at less than 5 percent.
Section 1.0 - Project Background and Objectives<br />
1.7.4 Design <strong>Wastewater</strong> Loads<br />
The design raw sewage BODs and TSS concentration criteria used in 1993 to plan the<br />
Lansdowne Road WWTP upgrade and expansion is:<br />
These values have been adopted for this study to permit evaluation of various options.<br />
The following design raw sewage BODS and TSS annual loadings are assumed at full<br />
development in the <strong>Blackburn</strong> area:<br />
The design raw sewage BOD5 and TSS a~mualoadings for a design population of<br />
115,000 at the Lansdowne Road WWTP is:<br />
The present 1999 raw sewage BODs and TSS annual loadings at the Lansdowne Road<br />
WWTP is estimated at:<br />
s ,.<br />
!:<br />
I<br />
.-:<br />
:-,.<br />
, .<br />
The proportion of BODs and TSS load h m the <strong>Blackburn</strong> sewage collection area, at<br />
full development in comparison to the design load capacity of the Lansdowne Road<br />
WWTP is calculated at less than 5 percent.<br />
1.7.5 Wet Weather Flow Impacts<br />
One factor that governs the need to expand a wastewater treatment plant is the wet<br />
weather flow component. This component of the flow is dependent on the following:<br />
Type of sewer system (separatefwmbined).<br />
Topography of the Seniced area (piping above or below the water table, possibility<br />
that manhole flooding occurs).<br />
. 1-8<br />
Waorrcrs~~~Gsrn 0r.w -.=.a8<br />
&'<br />
tI*l.W
Section 1.0 -Project Background and Objectives<br />
Physical characteristics of the underground piping (old/new/materials).<br />
rn<br />
Connection policies (roof drain connections, etc.).<br />
Review of wet weather flow mitigation policies and plans is essential. Should a<br />
reduction program prove practicable and cost effective, lower peak flows would occur<br />
after changes are implemented and thereby defer expanding plant infrastructure.<br />
1.7.6 Wet Weather Flows<br />
As detailed in the Stantec Consulting Ltd. report completed June, 1999, VI is a serious<br />
problem in the <strong>Blackburn</strong> sewage collection area and corrective action is required.<br />
The original 1976 design information for the Blackbum treatment facility lists the<br />
following criteria:<br />
rn Contributing population 2,500<br />
ADWF, m3/d 945<br />
In the future, as development exceeds 2,500 population, the facility would be doubled<br />
in capacity to accommodate a population of 5,000 with ADWF doubling, but PWWF<br />
remaining constant.<br />
Based on these design parameters, the lagoon facility would provide an eMuent<br />
quality of BOD6 20 mg/L and TSS< 20 mfl. Monitoring data from the City<br />
indicates that the facility up to now has reliably achieved these two targets and is in<br />
compliance with pennit requirements.<br />
It is important to note that the original design appears to have taken into consideration<br />
not only winter operating conditions, but also identified flow variations due to winter<br />
thaw conditions and spring raidthaw conditions. In the first stage of development,<br />
during wintedspring thaw conditions, because of the layout and locations of manholes<br />
and the coliection pipework, PWWF would be high, amounting to nearly 4.5 times<br />
ADWF, primarily because of inflow due to flooding around manholes adjacent to<br />
natural drainage streams. A second component would be due to infiltration due to wet<br />
ground andtor high groundwater conditions in Iow lying areas. In the second stage of<br />
development, UI would be reduced so that PWWF would remain at 4,350 m3/d and the<br />
PWWFlADWF ratio reduced to approximately 2.5.<br />
. .<br />
1<br />
,& 1 .<br />
- 1-9<br />
H .*mIIrnn>.3C*,,mmId Wnxll m<br />
mmm
Section 1.0 -Project Background and Objectives<br />
Rewrded results for 1999 indicate ADWF at 450 m3/d and PWWF at 4,500 rn3/d. The<br />
PWWF/ADWF ratio is 10:1, which is much greater than the design value of 4.6:l.<br />
The excessive I/I flows consume available capacity of the domestic sewage collection<br />
system as well as the Mackus Road pumpstation. Also because a large component of<br />
the flow is snowmelt, these flows measurably reduce sewage temperatures which<br />
impacts the efficiency of any treatment facility. Without an I/l reduction program in<br />
place, excessive III would limit future development in the Blackbum collection area<br />
because of limits on sewer capacity; and, as well jeopardize the operation of the<br />
treatment facility so that effluent quality is in non-compliance with permit<br />
requirements. The Stantec Consulting Ltd. report identified these issues. The report<br />
concluded that the most wst effective plan was to implement a rehabilitation program<br />
for VI reduction and reammendid as a first step that work be undertaken to seal<br />
manholes to reduce inflow.<br />
1.8 REGULATORY BACKGROUND<br />
1.8.1 <strong>Blackburn</strong> WWTP Discharge Permit<br />
The discharge permit for the <strong>Blackburn</strong> WWTP is covered under Pennit PE-3868. An<br />
amended permit was issued by BC MOELP on March 23, 1992, which requires that<br />
the plant eflluent meet the following not to exceed criteria:<br />
Discharge flow, m3/d 1,375<br />
The effluent quality must not exceed the above maximums based on a monthly<br />
composite sample made up of four grab samples taken over a two-hour period at<br />
maximum flow. The amended permit stipulates that although effluent disinfection is<br />
not required at this time, the existing chlorination facility must be maintained for use<br />
in the event that it is required in the future.<br />
1.8.2 Lansdowne Road WWTP Discharge Permit<br />
The discharge permit for the Landsdowne WWTP is covered under Permit PE-0146.<br />
An amended permit was issued by BC MOELP on March 29, 1996, which requires<br />
that the plant effluent meet the following not to exceed criteria:
Section 1.0 - Project Background and Objectives<br />
Discharge flow, m3/d 45,000<br />
The effluent quality must not exceed the above maximums based on a weekly<br />
composite sample made up of four grab samples taken over a two-hour period at<br />
maximum flow. The permit stipulates that although effluent disinfection is not<br />
required at this time, the existing chlorination and dechlorination facilities must be<br />
maintained for use in the event that faecal coliform contamination of water kom the<br />
College Heights well becomes evident in the future.<br />
1.8.3 BC Municipal Sewage Regulations<br />
The BC MOELP has recently published revised Waste Management Act, Municipal<br />
Sewage Regulation, which may have a future impact on updated permits for both<br />
plants. Any plant upgrade after July 15, 1999 will require an application to be made<br />
under these new regulations, which will impact the collection system, treatment and<br />
the effluent discharge requirements, indicated as follows:<br />
No sanitary sewer overflow (SSO) of less than 1 in 5 year return period will be<br />
allowed after January 1, 2004 unless there has been a liquid waste management<br />
plan (LWMP) where the population is > 10,000, or a study where the population is<br />
< 10,000, to quantify and qualify the SSO.<br />
Similarly for Vi, the maximum day flow should not exceed 2 times ADWF unless<br />
there has been a LWMP or study to address the issues.<br />
The aim will be to reduce the SSO's by 10 percent per year.<br />
Where there will be a treatment plant expansion to accommodate an increase in<br />
flow greater than 20 percent of the previous maximum authorized flow, an<br />
environmental impact study will be required.<br />
Any flow above 2 times ADWF will require primary treatment as a minimum, and<br />
primary and secondary emuent should be combined for discharge.<br />
The receiving water would require careful monitoring with a minimum acceptable<br />
40:l dilution ratio. Appropriate discharge locations would need to be identified<br />
that comply with regulations.<br />
The impact of the new Municipal Sewage Regulation on the future upgrading of the<br />
Blackbum wastewater system infrastructure needs to be considered in detail.
Section 1.0 -Project Background and Objectives<br />
1.8.4 Ammonia Toxicity<br />
In solution, ammonia exists in two forms, ionized ammonium (NH43, and unionized<br />
ammonia w3). Fractionation of these two species depends upon the water pH and<br />
temperature. At higher pH and temperature values, a greater fraction of the effluent<br />
ammonia will exist in he unionized form. It is this unionizd form which is toxic to<br />
aquatic life in relatively low concentrations.<br />
Neither <strong>Blackburn</strong> nor Lansdowne Road WWTPs are required to achieve an effluent<br />
ammonia concentration limit in their respective discharge permits. However, the new<br />
Municipal Sewage Regulation stipulate that the maximum allowable emuent ammonia<br />
concentration at the "end of pipe" must be determined from a back calculation from<br />
the edge of the initial dilution zone. The back calculation must consider the ambient<br />
temperature and pH characteristics of the receiving water and known water quality<br />
guidelines.<br />
Furthermore, the new Municipal Sewage Regulation stipulates that a person must not<br />
discharge effluent, unless "...the discharge passes a 96 hour LC50 bioassay test as<br />
defined by the Environment Canada's Biological Test Method, Reference for<br />
Determining Acute Lethality of Effects of Rainbow Trout (Reference Method EPS<br />
l/RM/13)".<br />
The above stipulation does not apply if "...the discharge is diluted such that at the<br />
outside boundary of the initial dilution zone, the dilution ratio exceeds 100:l and the<br />
discharger demonstrates to the satisfaction of the manager that the discharge does not<br />
adversely affect the receiving environment."<br />
Environment Canada's position is based on Section 36(3) of the Fisheries Act (198%<br />
which states: "No person shall deposit or permit the deposit of a deleterious substance<br />
of any type on water Wuented by fish. Environment Canada chooses to define<br />
deleterious substances in large part by means of the whole effluent- test, is. without<br />
dikution by the receiving water.<br />
In the event that existing <strong>Blackburn</strong> WWTP is upgraded or expanded, consideration<br />
will have to be given to designing the new plant to achieve year round or seasonal<br />
nitrification to reduce or remove the possibility of ammonia toxicity.
APPENDIX D<br />
DECISION WORKSHOP - OCTOBER 19,1999<br />
RANKINGICOMPARISON RESULTS
City of Prince George - Decision Workshop October 19. 1999
City Of Prince George - Decision Workshop Oclober 19, lYnu
City of Prince George - Decision Workshop October 19, 1999<br />
I I L I I I I<br />
OVERALL RESULTS'<br />
I-- --<br />
Wei$atlng . .-<br />
Ciiterin WelgM I 3 --<br />
Financial 3.5 7.0 17.5 15.8<br />
Performance - 2.3 12.8 10.5<br />
Operational 2.4 15.9 13.4 4.9<br />
Emriicnmental 1.7 11.2 4.3 5.2
APPENDIX C<br />
DECISION WORKSHOP - OCTOBER 19,1999<br />
WORKSHOP NOTES
MINUTES OF MEETING<br />
PR~ECT NAME:<br />
<strong>Blackburn</strong> <strong>Wastewater</strong> <strong>Treatment</strong> <strong>Plant</strong> <strong>Upgrade</strong> <strong>Study</strong><br />
LOCATION: PAGE: 10f1<br />
DATE OF October 19, 1999 OATE: November 1,1999<br />
MEETING:<br />
PROJECT NO.: 34918-00 -03<br />
CONTRACT NO.:<br />
PRESENT: Andy Ribul (AR)- City of Prince George - Dave Dyer (DD)- City of Prince George<br />
Norm Gobbi (NG)- City of Prince George - Bany Rabinowitz - RC<br />
Frank Blues (FB)- City of Prince George - LesNemeth -RC<br />
Gary Champagne (GC)- City of Prince George - Andy North - RC<br />
Ritch Girard - MOE<br />
- Stuart Lawrence - L&M Engineering<br />
PURPOSE:<br />
DlSTRlBClTlON TO<br />
ALL ABOVE AND:<br />
WRITTEN BY:<br />
Decision Workshop<br />
Stuart Lawrence<br />
DESCRlmlOPl<br />
Service Area Population - DD stated that the current service area population was<br />
closer to 1,500. BR stated that for the study an aggressive population growth rate<br />
has been assured to reach 5,000 population in 25 years = 4.2% growth.<br />
AR stated that rehabilitation work just started for VI control; 14 manholes done to<br />
date.<br />
FB interested in defaults of NPV's of 5 and 10 year yI rehab programs. LN<br />
handed out tables.<br />
FB asked if cost estimates for downtown sewer upgrades included cost estimates.<br />
LN stated that costs included in Options 1 to 5.<br />
Life cycle costs are all in 1999 dollars. O&M costs are those costs unique to each<br />
option.<br />
FB noted that these are slip problems along river banks, especially near correction<br />
facility. Needs preliminary assessment. Could rule out use of routing? May even<br />
be a problem along highway.<br />
Access to manholes along gravity route (road) could be difficult; 4m + turnarounds<br />
required.<br />
Land acquisition costs not included.<br />
Development potential with gravity main along Hwy 16.<br />
Animonic toxicity not a current issue.<br />
Mackus Rd. PS pumps need to be replaced now. What is correct pump size?<br />
These minutes are in the writer's best interpretation of discussions held<br />
during the meeting. Please inform the writer of any noteworthy omissions or<br />
errors.
APPENDIX B<br />
ESTIMATED CAPITAL AND 25 YEAR LIFE CYCLE<br />
COSTS
<strong>Blackburn</strong> WWTP <strong>Treatment</strong> Options<br />
Option 2 1<br />
Decommission <strong>Blackburn</strong> WWTPmransfer Flows to Lamdowoe Road WWTP<br />
I I I I I
<strong>Blackburn</strong> WWTP <strong>Treatment</strong> Options 1<br />
option 3 1<br />
.Modify <strong>Blackburn</strong> WWTP for Storagflransfer Flows to Lansdowne Road WWTP<br />
I I I I<br />
I<br />
I I I I<br />
Notes:<br />
Annual C&M cost for Blackbum sewage lagoons 1999-2007 is 545,000-$56,571<br />
Annual O&M cost for Blackbum storage lagoons 2008-2024 is $20,000<br />
-<br />
Incremenlal08rM cost for uealing Blackbum wastewater at Lansdowne Road WWTP2008-2024<br />
I I I I I I
Nores.<br />
Annual O&M cost for Blackbum sewage lagoons 1999-2007 is $45,000-$56371<br />
Annual O M cost for <strong>Blackburn</strong> sewage lagoons for PWWFueatmenl2008-2024 is $20.000<br />
Annual O M cmt for pumpstation 2008-2024 is $10,000 1<br />
-<br />
Incrementai 0&M cosl for treating Blackbum wastewater at Lansdowne Road WWTP 2008-2024<br />
I I 1 1 I I
[<strong>Blackburn</strong> ---<br />
WWTP <strong>Treatment</strong> Options 1 -- .- I I<br />
Option 5 1 1<br />
blaintain <strong>Blackburn</strong> WWTP for Flows>2*ADWFmraosfer ElowscZ*ADWF to Lansdowne Road WWTP<br />
I I I I I I<br />
Notes:<br />
Annual O&M oasi for <strong>Blackburn</strong> sewage lagoons 1999-2007 is $45.000-$56,571<br />
Annual O M cosl for <strong>Blackburn</strong> sewage lagoons for PWWF treatment 2008-2024 is $20,000<br />
incremental O&M cost lor treating <strong>Blackburn</strong> wastewater at Lansdowne Road WWTP 2008-2024<br />
I I I I I I
Blackbum WWTP <strong>Treatment</strong> Options<br />
Option 6a<br />
<strong>Upgrade</strong> and Expand <strong>Blackburn</strong> WWTP Lagoodo Nitrification<br />
! I I
<strong>Blackburn</strong> WWTP <strong>Treatment</strong> Options 1<br />
Option 7a<br />
Decommission <strong>Blackburn</strong> WWTP ~ @W~CO~S~NC~<br />
New Mechanical Secondary <strong>Plant</strong>/No Nitri6cation<br />
I I I I I I<br />
Notes: 1 1 1 1<br />
Annual O&M cost lor Blackbum sewage lagoons 1999-2007 is %45.OW$56,5?1<br />
Annual O&M cost for new Blackbum mechanical plant 2008 to 2024 is $129,362-$204,442<br />
I I I I I
APPENDIX A<br />
STANTEC CONSULTING LTD.<br />
STUDY CONCLUSIONS
City of Prince George<br />
<strong>Blackburn</strong> Sanitary Sewer<br />
InfltrationlInflow Studv - 1999<br />
Prepad lor:<br />
City of Prince George<br />
Prepared by:<br />
Stantec Comdtiug Ltd.<br />
June, 1999
5.0 CONCLUSIONS<br />
I<br />
'\<br />
-.<br />
5.1 RESULTS OF STUDY<br />
The study Field investigations included the folfowing works:<br />
instaliing flow muen in nine manholes,<br />
installing peak level indicaturs in six manhoIes,<br />
visd investigations incIuding observing and estimating observed inflow to<br />
selected doles.<br />
visual observations depth bf now titcough selected manholes.<br />
Cornpatisons were made between p ro-h theoretical generated flows at the manholes<br />
equipped with flow mtm, as well as a comparison of observed inflow estimates to the<br />
recorded inflow (recorded flow less theoretical gcncrared flows).<br />
Although estimated observed inflows an only esdmates, it appears that estimated<br />
observed inflows amounted to only approximately 75% of the recorded inflow. The.<br />
additional 25% may be h m manholes which were not open4 or may be from leaking<br />
mains or service connections. The 1991 tefevision camen inspectiom indicate that some<br />
infiltrarion to piping. either crackad or bmken pipes or service connections. was<br />
observed at that time.<br />
Two observed conditions w m<br />
possible mediation activities.<br />
of &gnificaot interest in arsessin~infl~wf~ltration and<br />
On March Zth, bH OKSW was observed to have storm water from a backedvp ditch<br />
flowing dictly into the rim On March 26th. City crews ched out the ditch and<br />
diverted stormwater away from this manhole. Flow mettr No. 7, downsaeam.<br />
immediately recorded a drop in fIow of ;rppmxhtely 400 cu.d&y. This ilfusaatcs<br />
tbat signifiwnf inflow an occur from only a few manhoIes if the rims are below the<br />
bund bl or below stonnwarer kvels. either in ditches, creeks oc standing water<br />
-<br />
during evly spring snowmelt.<br />
On Mmh 25. MH EAK43A exhibited inflow from the cover - the rim was below ground<br />
kvel and had standins W r around ir. On April 9, the sunding water had d-cd to<br />
below the rim of the manhok, however, leakage was observed from the bax of the<br />
ma~~hok. A simh situation was observed at MJi NKSjD, where on March 25, there<br />
was inflow from the rim and bricking and on Aprii 7, there was inflow from the base.<br />
Observations at these NO Imtions indicate that, although the worn inflows appear to<br />
occur during the firsr snow-mlt, iflows also continue 3s the thaws.<br />
I9<br />
c,lyotRinuetCorge<br />
Blrlburn Smiury Sever Infilmhdlnllwr Sm&<br />
,7,".l R m m . llln 19V9
As noted previously, comparisons of recorded flows to theoretical generated flows<br />
indicates that inflowlinfiluation appears to k the result of snowmelt or rainfall events.<br />
and does not occur yqr round. This comparison also indicates that, except for<br />
snowrne1tlr;linfall evenu. then is relatively little year-round infiltration to the <strong>Blackburn</strong><br />
system.<br />
This is important in understanding and mitigating inflowfinfiitration as both<br />
identification of problem arcy and monitoring the results of upgradiing works is<br />
effactiveiy limited to king done during thest events. Si rainfall events occur with on<br />
an irregular basis. the mos effective time ta identify problems and to manitor rtsSs of<br />
uppdiig wiil continue to be during the spring snow-melt period. A comparison of the<br />
1997, 1998 and 1999 snow melt events indicates that sp~g<br />
snow-melt and it's effect on<br />
the Blackbum sewer system can also vary widely so care will need to be taken in<br />
interpreting the results of upgrading activities.<br />
5.2 SUMMARY OF RECOMMENDATIONS FOR<br />
UPGRADING<br />
The recommendations of this study include:<br />
a) upgrading manholes. including repairs to manhole stmcnucs, cappinglxaling of<br />
unused connections and Suds and d i g and waterproofing mahhole~ subject to<br />
being overtopped by srorm wm. See Section 4.1 and 4.3 for derails.<br />
a) upgrading piping, as determined by the 1991 television camera work (if not already<br />
done)<br />
b) thorough cleanins of kouf sscdons of the sanitary sewer system prior to tdevision<br />
came~ins@o& to determine if inflow from broken pi& is occurring, and repair<br />
of any infiltratins piping. See Section 4.4 for details.<br />
C) monitoring of specific areas of the system prior to and during spriag mow melt in<br />
order to limit inflow from avoidable dirch~creck backup. See Section 4.2 for details.<br />
d) plumbing insptcrions to determine if basement sump pumps are insnlled and<br />
connected to the smiwry system.<br />
e) smoke testingto identify mof dr;lim or parking area drains c onnd to the sanirvy<br />
system.
CITY OF PRINCE GEORGE<br />
Forcemain from the existing<br />
<strong>Blackburn</strong> WWTP site to the<br />
high point on Graves Road.<br />
1,720m of 200 rnm dia. forcemain<br />
from the intersection of Mackus<br />
Road and North <strong>Blackburn</strong> Road<br />
to a high point on Highway 16.<br />
3,100rn of 200 mm dia. gravity<br />
sewer main from the end of the<br />
forcemain to the Regional<br />
Correctional Centre tie-in.<br />
100m of 200 rnm dia. sanitary<br />
sewer syphon from the Yellowhead<br />
Bridge to the intersection of 3rd<br />
Ave. and Taylor Drive.<br />
1 Wm of 300 mm dia. gravity sewer<br />
along Taylor Drive to the intersection<br />
with 15th Ave.<br />
180m of 300 rnm dia. gravity sewer<br />
along 15th Ave. from Taylor Drive<br />
to Birch St. Connect to existing<br />
525 mm dia. sewer main.<br />
------ Exist. Sanitary Collection Mains<br />
Prince George<br />
Airport<br />
J<br />
[J I<br />
,yJ<br />
LC'<br />
Blackbum Sanitary Collection Area<br />
I<br />
! City of Prince George<br />
<strong>Blackburn</strong> <strong>Wastewater</strong> <strong>Treatment</strong> <strong>Plant</strong><br />
<strong>Treatment</strong> Options <strong>Study</strong><br />
ENGINEERING LIMITED<br />
RECOMMENDED OPTION - FLOW TRANSFER<br />
Figure 6.1<br />
-
Section 6.0 -Recommended Option<br />
6.3 EXISTING DOWNTOWN SEWERAGE SYSTEM<br />
Flows transferred from the Blackbum catchment will connect into the existing<br />
sanitary sewer mains at the Regional Correctional Centre that ultimately<br />
discharge into the 600rnrn diameter City trunk sanitary sewermain on Taylor<br />
Drive.<br />
The estimated future peak pump flow rate h m the Mackus Road sewage lift<br />
station is 50 Us (4350 m3/d), based on the ultimate 5,000 population. With<br />
successll implementation of III reduction measures this flow rate could be<br />
reduced to 40 Us. The following upgrades are based on the more conservative<br />
50 L/s and should be reviewed at a detailed design stage. The section of<br />
existing 200mm diameter sewer main from the discharge point of the 200mm<br />
diameter syphon, at MH ~ ~ 2to 3 the a intersection of the 525mm diameter<br />
main at Birch Street, will need to be upgraded to a 300mrn diameter pipe at a<br />
minimum grade of 0.3% to handle the future pumped peak flows of<br />
approximately 0.05 m3/s.<br />
The section of gravity sewer main which requires upgrade totals 430 meters in<br />
length.<br />
The wst for this upgrading work (which requires significant road restoration)<br />
at a unit cost of $250 per lineal metre is 430 x 5250 is approximately $107,500.<br />
This cost includes all associated appurtenances, manholes and restoration<br />
costs. Pipe bursting could be considered during the predesign stage as an<br />
alternative to reduce restoration costs.<br />
Flow capacity of existing mains on the Yellowhead Bridge and within the<br />
subdivision on the west side of the Fraser River are listed in Appendix E.<br />
6.4 UPGRADING PLAN<br />
The City's accelerated 3-4 year implementation plan is to decommission the<br />
existing Blackbum WWTP by 2003, and all flows transferred for treatment at<br />
the Lansdowne Road WWTP via a new forcemain and trunk gravity sewer<br />
from the Mackus Road pumpstation. An accelerated III reduction program is<br />
to be initiated and completed to reduce the volume of wastewater being<br />
transferred during wet weather and snowmelt conditions. The existing Mackus<br />
Road pumpstation is to be upgraded and a new, small pumpstation constructed<br />
at the <strong>Blackburn</strong> WWTP site to transfer flows generated in the area adjacent to<br />
the plant to the Mackus Road pumpstation.
Section 6.0 -Recommended Option<br />
Key activities or capital works associated with the upgrading plan are as<br />
follows:<br />
Implement and complete VI reduction program.<br />
Decommission lagmns and rehabilitate site for other use.<br />
<strong>Upgrade</strong> Mackus Road pumpstation to handle projected increasd flows.<br />
Construct trunk gravity sewer and forcemain to transfer all flows from<br />
<strong>Blackburn</strong> sewerage area to Lansdowne Road WWTP.<br />
<strong>Upgrade</strong> downtown sewage collection pipework to handle increased flows<br />
from Slackburn sewerage a&.<br />
Construct sewage purnpstation at Blackbum W P site and construct<br />
connecting forcemain discharging to Mackus Road pumpstation.<br />
6.5 OPTION 1 DESIGN INFORMATION<br />
Population<br />
ADWF, m3/d<br />
PWWF, m3/d<br />
Pipework<br />
Forcemain from intersection of Mackus Road and North<br />
Blackbum Road to a high point on Hwy. 16.<br />
Diameter, mm 200<br />
Length, m 1,720<br />
Gravity sewer main from the end of 200 forcemain to the<br />
Regional Correctional Centre tie-in<br />
Diameter, rnrn 300<br />
Length, m 3,100<br />
Forcemain from the existing <strong>Blackburn</strong> WWTP site to the high<br />
point on Graves Road<br />
Diameter, mm 150<br />
Length, m 1,330<br />
Sanitary sewer syphon connecting to downtown sewage<br />
collection system<br />
Diameter, mm<br />
Length, m
Section 6.0 -Recommended Option<br />
Gravity sewer upgrade, along Taylor Drive, 15" Ave, Ash Street<br />
to Birch Street; connect to 525 diameter sewer.<br />
Diameter, mm<br />
Length, m<br />
Pumpstation<br />
<strong>Upgrade</strong> Mackus Road PS for PWWF capacity of 50 Us; 1<br />
duty/l standby pumps, plus back-up power.<br />
Suppiy and install PS at existing <strong>Blackburn</strong> WWTP site to<br />
service residence along Foreman and Graves Roads; capable of<br />
pumping 5 US; 1 duty11 standby pumps.<br />
Miscellaneous<br />
R&oreflandscape existing Blackbum WWTP site.<br />
6.6 PROJECT STAGING<br />
Stage 1 (2000-2001)<br />
Complete inflow rehabilitation work to reduce flows by 2,170 m3/d.<br />
Complete accelerated 3 year infiltration rehabilitation work to reduce<br />
flows by an additional 1,070 m3/d, using the following techniques:<br />
> Video inspectionkmoke testing of pipelines.<br />
3 Repair MH's.<br />
> Repair leaking pipework.<br />
> Repair private connections.<br />
9 Repair municipal connections.<br />
Stage 2 Predaign Option I (2001)<br />
New forcemain and gravity trunk sewer from Mackus Road PS to<br />
Regional Correctional Centre tie-in.<br />
Downtown sewer work<br />
Mackus Road PS upgrades<br />
New forcemain from Blackbum JWTF site to connect to Mackus Road<br />
PS<br />
Foreman Road PS<br />
<strong>Blackburn</strong> WWTP restorationilandscaping<br />
Stage 3 (2002)<br />
Complete 111 reduction program so that PWWF/ADWF=2.0<br />
6-4<br />
34 ' P%O>ECT~'ZW~~~I~~."JJI~~~~<br />
R-',m> h
Section 6.0 -Recommended Option<br />
Complete detailed design Option 1<br />
Stage 4 (2003)<br />
Complete construction of Option 1<br />
6.7 OVERALL IMPLEMENTATION PROGRAM<br />
An implementation program and capital expenditure plan have been developed<br />
to meet the City's wastewater coHection and treatment needs until 2024. The<br />
plan has been designed to defer capital costs where feasible. A summary of the<br />
overall implementation program and associated capital expenditures is<br />
presented in Table 6.1.<br />
Table 6.1 OveraI1 ~rn~lementation Program<br />
2001 IInfltration mitigation & predesign Option 1<br />
2002 lComplete infiltration mitigation & detailed design Option 1<br />
1 2003 (Complete construction of Option 1
SECTION 6<br />
RECOMMENDED OPTION
SECTION 6.0<br />
RECOMMENDED OPTION<br />
6.1 INTRODUCTION<br />
Both economic and non-economic criteria were used to evaluate each of the<br />
seven upgrarllng options presented in this report. Combining the results of the<br />
Decision Workshop in the evaluation, the recommended upgrading plan for the<br />
<strong>Blackburn</strong> sewerage area is Option 1. Option 1 involves completion of the III<br />
mitigation measures, decommissioning the Blackbum WWTP and pumping all<br />
sewage currently treated at the plant to the Lansdowne Road WWTP. A plan<br />
of the recommended option is presented in Figure 6.1.<br />
This section outlines the basic requirements for the recommended upgrading<br />
plan. For this option, sewerage upgrades are discussed with the aim of<br />
presenting an implementation plan that satisfies the necessary environmental<br />
requirements while at the same time minimizing capital expenditures by<br />
adopting a staged upgrade approach. There are significant capital investments<br />
required to complete yI reduction and transfer <strong>Blackburn</strong> flows to the<br />
Lansdowne Road WWTP. However, by adopting a "just-in-time"<br />
implementation plan, the City should be able to defer required expenditures<br />
until they are absolutely necessary. This approach will also allow the City to<br />
consider the impact of population growth projections for the <strong>Blackburn</strong> area.<br />
6.2 REDUCED INFLOWflNFILTRATION<br />
As detailed in Section 2, there are two possible approaches to completing the<br />
VI rehabilitation program. One is a five year program and the other is a 10<br />
year program. However, the City plans to adopt an accelerated 3 to 4 year<br />
program with the goal of meeting BC Municipal Sewage Regulations for<br />
ADWF and PWWF flow requirements by 2004 and at the same time ensuring<br />
compliance with the discharge permit for the Blackbum WWTP.<br />
Recommended MH repair's will be completed by the end of 2000; as well as<br />
video inspection and smoke testing of pipelines plus complete readily<br />
repairable VI and complete 'off-street' mode to eliminate VI from roof,<br />
perimeter foundation and yard connections.
SECTION 5<br />
EVALUATION OF OPTIONS
SECTION 5.0<br />
EVALUATION OF OPTIONS<br />
5.1. DECISION CRITERIA<br />
5.1.1 Introduction<br />
The purpose of this section is to establish the framework for a Decision<br />
Workshop as part of the Blackbum WWTP treatment options study. Under<br />
consideration are potential options for treating wastewater either at an<br />
upgraded Blackbum WWTP or by transferring the flows to the larger<br />
Lansdowne Road WWTP.<br />
This section presents a process that can assist the decision makers in evaluating<br />
the recommendations for new projects and programs to meet the hture<br />
wastewater treatment requirements of the Blackbum sewage collection area.<br />
The planning framework and model used to evaluate the options and arrive at a<br />
series of conclusions is presented. It must be noted that this process utilizes a<br />
series of tools which, when combined with other criteria, will assist the overall<br />
decision making process.<br />
The following key elements of the project were addressed during the Decision<br />
Workshop held with City staffon October 19, 1999:<br />
A total of 7 potential upgrade options and two sub-options presented for<br />
evaluation using both economic and non-economic criteria.<br />
A decision is required about whether to maintain two separate wastewater<br />
treatment piants or provide one consolidated plant at the Lansdowne Road<br />
WWTP site.<br />
If a consolidated plant at Lansdowne Road is selected as the preferred<br />
option, a decision is required as to the preferred transfer pipeline route and<br />
configuration between the Blackbum sewage collection area and the<br />
Lansdowne Road WWTP.<br />
The issue of ammonia toxicity on the receiving water from a <strong>Blackburn</strong><br />
WWTP discharge needs to be addressed within the workshop process.<br />
In each of the above four elements, the selection of the most appropriate option<br />
is not simply an economic issue. Various economic and non-economic factors<br />
must be taken into consideration. One of the most important elements that<br />
feeds into the decision process is the establishment of the planning criteria
Section 5.0 -Evaluation of Ootions<br />
used by stakeholders to compare options. The planning criteria reflect what is<br />
important to stakeholders when making decisions about wastewater system<br />
upgrade options. Evaluation criteria that were developed through Reid<br />
Crowfher's experience on similar projects elsewhere are presented below. The<br />
list of factors or criteria that form the basis for the comparative evaluation of<br />
the options have been categorized into the following four criteria:<br />
Cost criteria<br />
Technical criteria<br />
Operational criteria<br />
Environmental and aesthetic criteria<br />
Within each category there are many evaluation criteria, however to ensure<br />
that the process is neither too complex nor time consuming, a specific selection<br />
of evaluation criteria have been chosen.<br />
5.1.2 Cost Criteria<br />
Cost criteria relate to short-term and long-term expenditures. Capital costs and<br />
operating and maintenance (O&M) costs are the two major components used in<br />
cost comparisons. Together, these components define the life-cycle cost.<br />
Capital Cost<br />
This cost is a measure of the immediate cost that may be subject to<br />
fmancing. The least risk is attached to this cost; i.e. it will occur regardless<br />
of long-term variations in plant loads, fmancing, etc.<br />
Life-Cycle Cost<br />
Tnis cost is a measure of the total project cost over its design life. It<br />
includes the capital cost, but also incorporates O&M expenditures and the<br />
ultimate salvage value. Life-cycle costs are expressed in "present value"<br />
dollars.<br />
5.1.3 Performance Criteria<br />
Generally, criteria falling within this category are related to the ability of the<br />
facility to meet its objectives consistently. These criteria will be reflected in<br />
the costs; i.e. where a facility is judged less capable of meeting the<br />
performance standards, a greater safety factor will be included in the design.<br />
However, with any facility, there remains some risk that it will not perform up<br />
to expectations. It is this risk that is reflected in the perfomance criteria. The<br />
following are the performance criteria suggested for evaluating alternatives:
Section 5.0 -Evaluation of Options<br />
Reliability and Robustness<br />
The proven ability of the system upgrade to satisfy design objectives or<br />
reguiatory requirements and the ability of the system to operate<br />
successfully under adverse conditions and fluctuating influent<br />
characteristics.<br />
FlexibilitylComplexityISophistication<br />
The ability of the system to be modified or operated in another mode to<br />
meet short-term or long-term requirements and the amount and frequency<br />
of control or operator input that will be required to have the facility/system<br />
be successful in its intended application.<br />
Ease of Construction and Land Requirements<br />
The potential impact on existing operations and/or current land ownership<br />
when new facilities/systemsare built.<br />
5.1.4 Operational Criteria<br />
Operational criteria include those that affect the effort of and acceptance by the<br />
plant's operating and maintenance staff. A system that is difficult to<br />
comprehend or that requires a significant ongoing labour commitment is less<br />
likely to be operated with due diligence. When this occurs, notwithstanding<br />
design intent, a system will not perform to its capabilities. Operational criteria<br />
used in alternative evaluation include the following:<br />
Ease of Operation and Maintenance<br />
The "friendliness" of the system to operator control and the ease with<br />
which equipmentkystems may be removed from service, maintained, and<br />
returned to service. In addition, this criterion should reflect the frequency<br />
and duration of maintenance efforts.<br />
Safety<br />
Although wastewater systems design incorporates the necessxy safety<br />
measures, some facilities are more inherently safe than others. This<br />
criterion is intended to reflect that characteristic.<br />
Stamng<br />
Tne number of operations and maintenance personnel required to operate<br />
the facility.<br />
5.1.5 Environmental and Aesthetic Criteria<br />
Environmental and aesthetic criteria relate to off-site impacts of the<br />
facilityfsystern. Those relating to receiving water quality are extremely<br />
important to the success of this project.
Section 5.0- Evaluation of Options<br />
Effect on Surrounding Area<br />
The potential for degradation of the surrounding area (e.g. the receiving<br />
water quality, or transfer pipeline routes) under normal and upset operating<br />
conditions.<br />
Odonr PotentiallAir Emission<br />
The potential for malodorous gas release from a system under normal and<br />
upset conditions.<br />
VisuaVNoiselTraffic<br />
A measure of the visual obtrusiveness of the system or facility, the<br />
magnitude of noise generation and the amount of buck traffic associated<br />
with the system.<br />
The cost criteria for the various options have been developed within this<br />
document. In cases where there is no significant difference in the life cycle<br />
costs of two options, the decision regarding the preferred option must be based<br />
on the non-economic criteria listed above. During the Decision Workshop, the<br />
key project elements were evaluated using both the economic and noneconomic<br />
criteria by the technical and administrative personnel from the City,<br />
a representative from MOE and key project team members from the Reid<br />
Crowther team.<br />
5.2 EVALUATION TECHNIQUES<br />
5.2.1 Introduction<br />
There are a variety of techniques that can be used to assist decision-makers<br />
with selacting options. The most usefd technique nil1 depend on the nature<br />
and magnitude of the trade-offs identified and the stakeholders involved.<br />
There are a variety of recognized technical methods available, which vaty<br />
considerably in complexity and include:<br />
Holistic assessment<br />
Options are ranked based on structural information, but no formal decision<br />
model. Trade-offs are implicit using this technique which could be<br />
considered to be too judgmental for this project.<br />
Pair-wise comparison<br />
Each of the criteria b m every option is paired with all other options and<br />
individually evaluated or scored based on which perfoms best.
Section 5.0 -Evaluation of Options<br />
Rating and weighting<br />
The criteria are first technically rated and these scores are modified by<br />
assigning a weighting determined from the stakeholders preferences to the<br />
options , to produce a matrix of results.<br />
Multi-attribute trade-off analysis<br />
The most complex technique, best suited to a large number of options and<br />
criteria, but not considered appropriate for this process.<br />
Based on the options requiring evaluation, the planning team has therefore<br />
defmed the following two approaches for assisting in option selection:<br />
5.2.2 Weighted Analysis of Evaluation Criteria<br />
In this technique the ratings are numerical values to be developed on specific<br />
quantitative and qualitative results at the workshop. In the first step,<br />
participants are asked to weight the relative importance of the four criteria, i.e.<br />
cost criteria, technical criteria, operational criteria, and environmentaVaesthetic<br />
criteria, using a total of 10 points, see Form 5.1. In the second step,<br />
participants are asked to weight each of the criteria using a 10-point scale, see<br />
Form 5.2. These two initial steps help to identify the overall level of<br />
importance that participants place on individual criteria. Each option can then<br />
be ranked for each criterion on a score of 1 to 5 (poor to excellent) and then the<br />
weights are applied to the results of the ranking exercise, see Form 5.3.<br />
5.2.3 Pair - Wise Comparison<br />
A oneon-one decision matrix comparison process is utilized to establish the<br />
individual criteria rankings of each of the options, see Form 5.4. Within each<br />
criteria matrix, each option is paired with every other option and evaluated<br />
against each of the criteria. The option that performs best is assigned a value<br />
based on a 'pass - fail' as follows:<br />
if the option is better, a score of 1 is assigned;<br />
if the option is worse, a score of 0 is assigned; and<br />
if the option is no better or no worse, a score of 0.5 is assigned.<br />
By summing up the values for each option, this approach provides an<br />
indication of which option is technically superior. The drawback of this<br />
approach is that it does not take into account the magnitude or extent of the<br />
performance of one option versus another. It also does not take into account
Section 5.0 -Evaluation of Options<br />
part, be addressed by adding the weighting factors to the results and by using<br />
the following approach in parallel.<br />
5.3 EVALUATION RESULTS<br />
Attached as Appendix C and D are the results of the October 19, 1999<br />
Decision Workshop. Attending this workshop were the following individuals:<br />
City of Prince George<br />
Gary Champagne<br />
Andy Zbul<br />
DaveDyer<br />
Frank Blues<br />
Norm Gobbi<br />
MOELP<br />
Ritch Girard<br />
L&M Engineering<br />
Reid Crowther<br />
Bany Rabinowitz<br />
LesNemeth<br />
Andy North<br />
Form 5.1 was completed by each member of the Decision Workshop. A<br />
weighting number for cost, technical, operational and mvironmentaVaesthetic<br />
factors was developed based on the averaged group scores. Cost was weighted<br />
highest followed by operational and technical criteria, with environmental and<br />
aesthetic criteria weighted lowest. Form 5.2 was similarly developed from<br />
individual scores to weight the individual evaluation criteria.<br />
Form 5.3 lists the ranking of each of the options 1 to 7 based on the weighting<br />
numbers developed in Form 5.2. The ranking results for the options indicates<br />
that Option 1 (score 268) and Option 2 (score 286) are the most favoured<br />
options, options 3 to 6 score similarly (in the range 227 to 238), and the least<br />
favoured option is Option 7 (score 175).
Section 5.0 -Evaluation of Options<br />
Subsequent to the ranking results developed in Form 5.3, the participants<br />
completed Form 5.4, by using the pair-wise comparison technique, with the<br />
scores modified by incorporating the weighting results &om Form 5.1. The<br />
overall results were similar to the r;lting/weighting exercise as these results<br />
indicated that the preferred options are Option 1 (score 46.9) and Option 2<br />
(score 44.2), and the least preferred option is Option 7 (score 10.8).<br />
The similarity in the results provides a level of confidence that the decision<br />
techniques are robust. As Options 1 and 2 scored the highest in both<br />
techniques, discussion at the workshop then concentrated on identifying the<br />
preferred option for recommendation. As identified in the earlier sections both<br />
options achieve similar objectives primarily through alternative flow transfer<br />
routes. Consensus at the workshop was that the certainty of the route from<br />
Option 1 was greater than that for Option 2, and the construction of the Option<br />
1 alignment was likely to have more potential to encourage further<br />
development.<br />
The recommendation of the Decision Workshop members based on the ranking<br />
and comparison results is therefore to pursue Option 1.
Section 5.0 -Evaluation of Options<br />
FORM 5.1<br />
Relative Weightings of the Decision Criteria<br />
Groupings to be Used in the Evaluation<br />
Cost Criteria<br />
Technical Criteria<br />
Operational Criteria<br />
Environmental and Aesthetic Criteria<br />
Total 10
Section 5.0 - Evahation of Options<br />
FORM 5.2<br />
Specific Weighting of the Decision Criteria<br />
to be Used in the Evaluation<br />
Cost Criteria (Max = 10)<br />
Ca~ital Cost<br />
Life-Cycle Cost<br />
Technical Criteria I (Max. = 10)<br />
ReliabilityRobustness<br />
Flexibility I complexity /<br />
Sophistication<br />
Ease of Construction j~and<br />
Requirements<br />
I<br />
I<br />
Operational Criteria (Max. = 10)<br />
Ease of Operation and<br />
Maintenance<br />
Safety<br />
Staffing<br />
Environmental and Aesthetic Criteria I (Max. = 10)<br />
Effect on Surrounding Area I I<br />
Visual / Noise I Traffic
Section 5.0 -Evaluation of Options<br />
FORM 5.3<br />
Non-Economic Comparison between Options<br />
I Cost Criteria 1 (Max.=5) 1 (Max. =5) 1<br />
I Capital cost I I I<br />
Life-Cycle Cost<br />
Technical Criteria<br />
(Max- = 5) (Max. = 5)<br />
I<br />
Flexibility I Complexity /<br />
Souhistication<br />
Ease of Construction I Land<br />
Requirements<br />
I Operational Criteria I (Max. = 5) [ (Max. = 5) 1<br />
I<br />
Ease of Operation and<br />
Maintenance<br />
I safety I I I<br />
I Staffing I I I<br />
Environmental and Aesthetic Criteria<br />
Effect on Surrounding Area<br />
Odours/Emissions<br />
Visual / Noise / Trafic<br />
fi<br />
Totals I<br />
(Max. = 5) (Max. = 5)
Section 3.0 - Evaluation of Options<br />
FORM 5.4<br />
Example Pair-Wise Comparison Matrix<br />
I Total<br />
I
SECTION 4<br />
WASTEWATER TREATMENT OPTIONS
SECTION 4.0<br />
BLACKBURN TREATMENT OPTIONS<br />
The following seven options have been identified for upgrading the <strong>Blackburn</strong><br />
sewage collection area and WWTP:<br />
4.1 OPTION 1 - DECOMMISSION EXISTING BLACKBURN WWTP AND<br />
ROUTE ALL FLOW TO LANSDOWNE ROAD WWTP MA<br />
FORCEMAINlGRAVITY SEWER CONNECTION<br />
4.1.1 Outline<br />
In this option the existing sewage lagoons would be decommissioned and all<br />
flows transferred for treatment at the Lansdowne Road WWTP via a new<br />
forcemain and trunk gravity sewer from the Mackus Road pumpstation. A<br />
schematic representation of this option is presented in Figure 4.1. An I/l<br />
reduction program is to be initiated and completed to reduce the volume of<br />
wastewater being transferred during wet weather and snowrnelt conditions.<br />
The existing Mackus Road pumpstation would be upgraded and a new , small<br />
purnpstation would be constructed at the Blackbum WWTP site. It is believed<br />
that he hdowne Road WWTP has sufficient capacity to handle the<br />
projected future hydraulic and BODOSS Ioadings from the Blackbum sewage<br />
collection area.<br />
Key activities or capital works associated with this option are as follows:<br />
Implement and complete I/I reduction program.<br />
Decommission lagoons and rehabilitate site for other use.<br />
<strong>Upgrade</strong> Mackus Road pumpstation to handle projected increased flows.<br />
Construct trunk gravity sewer and/or forcemain to transfer all flows from<br />
Blackbum sewerage area to Lansdowne Road WWTP.<br />
<strong>Upgrade</strong> downtown sewage collection pipework to handle increased flows<br />
from Blackbum sewerage area.<br />
Construct sewage purnpstation at <strong>Blackburn</strong> WWTP site and construct<br />
connecting forcemain discharging to Mackus Road pumpstation.
Initiate 1 reduction program and<br />
complete over 5/10 years;<br />
assess PWWF based on results.<br />
0 Decommission existing <strong>Blackburn</strong><br />
WWTP and restorellandscape site.<br />
a Route all flow to Lansdowne Road<br />
WWTP.<br />
Pipeline route (m n B) from Mackus<br />
Road PS to Correctional<br />
.<br />
Centre tie-in.<br />
Pipeline route ( m .)from new PS at<br />
decommissioned <strong>Blackburn</strong> WWTP<br />
site to Mackus Road PS.<br />
a Assess conditionlcapacity of existing<br />
Mackus Road PS.<br />
e Assess conditionlcapacity of existing<br />
sewage conveyance system through<br />
downtown area.<br />
Assess impact of added sewage flow<br />
on Lansdowne Road WWTP<br />
capacityloperation.<br />
LEGEND:<br />
. - - - - - - Exist. Sanitary Collection Mains<br />
Bbckburn Sanitary Collection Area<br />
City of Prince George<br />
<strong>Wastewater</strong> <strong>Treatment</strong> <strong>Plant</strong><br />
<strong>Treatment</strong> Options <strong>Study</strong><br />
OPTION 1<br />
Figure 4.1
Section 4.0 - Blackbum <strong>Treatment</strong> Options<br />
Key technical issues associated with this option are as follows:<br />
Extent to which the VI reduction program is able to reduce peak wet<br />
weather flows must be evaluated.<br />
City need operate only one wastewater treatment and disposal facility.<br />
Major capital works needed to transfer flows to Lansdowne Road WWTP.<br />
Condition and capacity of the existing Mackus Road pumpstation must be<br />
evaluated.<br />
Details for pipeline routes for transferring Blackbum sewage flows to<br />
Lansdowne Road WWTP must be evaluated.<br />
Impact of added flow on capacityloperation of Lansdowne Road WWTP<br />
needs to be evaluated.<br />
Ammonia toxicity issue addressed at Lansdoume Road WWTP.<br />
4.1.2 Design Information<br />
Population<br />
ADWF, m3/d<br />
PWWF, m31d<br />
Pipework<br />
Forcernain from intersection of Mackus Road and North<br />
<strong>Blackburn</strong> Road to a high point on Hwy. 16.<br />
Diameter, mm<br />
Length, m<br />
Gravity sewer main from the end of 200 diameter forcemain to<br />
the Regional Correctional Centre tie-in<br />
Diameter, rnrn<br />
Length, m<br />
Forcemain from the existing Blackbum WWTP site to the high<br />
point on Graves Road<br />
Diameter, mrn<br />
Length, m<br />
Sanitary sewer syphon from Yellowhead Bridge connecting to<br />
downtown sewage collection system<br />
Diameter, mm<br />
Length, m<br />
Gravity sewer to intersection of isth Ave. and Taylor Drive;<br />
construct new manhole
Section 4.0 - Blackbum <strong>Treatment</strong> Ovtions<br />
Diameter, mrn 300<br />
Length, m 100<br />
Gravity sewer along l5Ih ~ ve. from Taylor Drive to Birch Street;<br />
connect to 525 diameter sewer<br />
Diameter, mm 300<br />
Length, m 180<br />
Pumpstation<br />
<strong>Upgrade</strong> Mackus Road PS for PWWF capacity<br />
Supply and install PS at existing Blackbum WWTP site to<br />
senice residence along Graves and Foreman Roads; capable of<br />
pumping 10 percent of PWWF.<br />
Miscellaneous<br />
Restordlandscape existing Blackbum WWTP site.<br />
4.1.3 Cost Estimate<br />
Pipework<br />
1 5 0 forcemain, S 1 00/m<br />
200 forcernain, $1 8O/m<br />
200 syphon, $200/m<br />
300 gravity sewer<br />
<strong>Blackburn</strong>, $1 60/m<br />
Downtown, $250/m<br />
Pumpstation<br />
Mach Road PS, LS<br />
Foreman Road PS, LS<br />
Miscellaneous<br />
Blackbum WWTP site restoration/lmdscaping, LS<br />
Subtotal<br />
Contingencies (15 percent)<br />
EngineeringIAdministration (20 percent)<br />
GST (3 percent)<br />
TOTAL<br />
4.2 OPTION 2 - DECOMMISSION EXISTING BLACKBURN WVTP AND<br />
ROUTE ALL FLOW TO LANSDOWNE ROAD WWTP VIA GRAVITY<br />
SEWER CONNECTION<br />
4.2.1 Outline<br />
In this option the existing sewage lagoons would be decommissioned and all<br />
flow transferred for treatment at the Lansdowne Road WWTP via a new trunk<br />
gravity sewer. A schematic representation of this option is presented in Figure
Section 4.0 - Blackbum <strong>Treatment</strong> Options<br />
4.2. An UI reduction program is to be initiated and completed to reduce the<br />
volume of wastewater being transfmed during wet weather and snowmelt<br />
conditions. The existing Mackus Road pumpstation would be upgraded. It is<br />
believed that the Lansdowne Road WWTP has sufficient capacity to handle the<br />
projected future hydraulic and BOD5tTSS loadings from the Blackbum sewage<br />
collection area.<br />
Key activities or capital works associated with this option are as follows:<br />
Implement and complete VI reduction program.<br />
Decommission lagoons and rehabilitate site for other use.<br />
<strong>Upgrade</strong> Mackus Road pu&pstation to handle projected increased flows.<br />
Construct trunk gravity sewer to transfer all flows from <strong>Blackburn</strong><br />
sewerage area to Lansdowne Road WWTP.<br />
<strong>Upgrade</strong> downtown sewage collection pipework to handle increased flows<br />
from <strong>Blackburn</strong> sewerage area.<br />
Key technical issues associated with this option are as follows:<br />
Extent to which the If1 reduction program is able to reduce peak wet<br />
weather flows must be evaluated.<br />
City need operate only one wastewater treatment and disposal facility.<br />
Major capital works needed to transfer flows to Lansdowne Road WWTP.<br />
Condition and capacity of the existing Mackus Road pumpstation must be<br />
evaluated.<br />
Details for pipeline routes for transferring <strong>Blackburn</strong> sewage flows to<br />
Lansdowne Road WWTP must be evaluated.<br />
Ammonia toxicity issue addressed at Lansdowne Road WWTP.<br />
4.2.2 Design Information<br />
Population<br />
ADWF, m3/d<br />
PWWF, m3/d
Initiate I11 reduction program and<br />
complete over 5110 year period;<br />
assess PWWF based on results.<br />
Decommission existing Blackbum<br />
WWTP and restorellandscape site.<br />
Route all flow to Lansdowne Road<br />
WWTP.<br />
Pipeline route (a m rn a) from Blackbum<br />
WWTP site to Correctional Centre tie41<br />
Assess conditionlcapacity of existing<br />
Mackus Road PS.<br />
Assess conditionlcapaciiy of existing<br />
sewage conveyance system through<br />
downtown area.<br />
Assess impact of added sewage flow<br />
on Lansdowne Road WWTP<br />
capacityloperation.<br />
LEGEND:<br />
Exist. Sanitary Collection Mains<br />
Blackbum Sanitary Collection Area<br />
City of Prince George<br />
<strong>Blackburn</strong> <strong>Wastewater</strong> <strong>Treatment</strong> <strong>Plant</strong><br />
<strong>Treatment</strong> Options <strong>Study</strong><br />
OPTION 2<br />
Figure 4.2
Section 4.0 - <strong>Blackburn</strong> <strong>Treatment</strong> Options<br />
Pipework<br />
Gravity sewermain from the existing Blackbum WWTP site to<br />
the Regional Correctional Centre tie-in<br />
Diameter, mm<br />
Length, m<br />
Sanitary sewer syphon from Yellowhead Bridge connecting to<br />
downtown sewage collection system<br />
Diameter, mm<br />
Length, m<br />
Gravity sewer to intersection of l5Ih Ave. and Taylor Drive;<br />
construct new manhole<br />
Diameter, mm<br />
Length, m<br />
Gravity sewer along 15" Ave. from Taylor Drive to Birch St.;<br />
connect to 525 diameter sewer<br />
Diameter, mm<br />
Length, m<br />
Pumpstation<br />
<strong>Upgrade</strong> Mackus Road PS for PWWF capacity<br />
Miellaneous<br />
Restoreflandscape existing <strong>Blackburn</strong> WWTP site.<br />
4.23 Cost Estimate<br />
Pipework<br />
200 syphon, $200/m<br />
300 gravity sewer<br />
<strong>Blackburn</strong>, $160/m<br />
Downtown, $250/m<br />
Pumpstation<br />
Mackus Road PS, LS<br />
Miscellaneous<br />
Btackburn M P site restoratiodandscaping, LS<br />
Subtotal<br />
Contingencies (15 percent)<br />
EngineerindAdministration (20 percent)<br />
GST (3 percent)<br />
TOTAL
Section 4.0 - Blackbum <strong>Treatment</strong> Options<br />
4.3 OPTION 3 - USE EXISTING BLACKBURN WWTP FOR<br />
EOUALIZATIONlSTORAGE AND TRANSFER ALL FLOWS TO<br />
4.3.1 Outline<br />
In this option the existing sewage lagoons would be converted to flow<br />
equalization/storage basins, and all flows transferred for treatment at the<br />
Lansdowne Road WWTP. A schematic representation of this option is<br />
presented in Figure 4.3. The principal beneiit of this option is that the peak<br />
flows being transferred from the Blackbum sewage collection area to the<br />
Lansdowne Road WWTP would be attenuated somewhat. An I/I reduction<br />
program is to be initiated and completed to reduce the volume of wastewater<br />
being transferred during wet ieather and snowmelt conditions. Tne existing<br />
Mackus Road pumpstation would be upgraded. It is believed that the<br />
Lansdowne Road WWTP has sufficient capacity to handle the projected future<br />
hydraulic and BODDSS loadings from the <strong>Blackburn</strong> sewage collection area.<br />
Key activities or capital works associated with this option are as follows:<br />
Implement VI reduction program.<br />
Modify lagoons for use as flow equalizationk.torage basins.<br />
<strong>Upgrade</strong> Mackus Road pumpstation to handle projected increased flows.<br />
Construct trunk gravity sewer to transfer all flows fiorn Blackbum<br />
sewerage area to Lansdowne Road WWTP.<br />
<strong>Upgrade</strong> downtown sewage collection system to handle increased flows<br />
from Blackbum sewerage area.<br />
Key technical issues associated with this option are as follows:<br />
Extent to which the LfI reduction program is able to reduce peak wet<br />
weather flows must be evaluated.<br />
City must maintain operation of storage basins; O&M costs of<br />
equalizationktorage basins are only slightly lower than O&M costs for the<br />
existing treatment lagoons.<br />
Major capital works needed to transfer flows to Lansdowne WWTP and<br />
modify lagoons.
Initiate llt reduction program and<br />
complete over 511 0 year period;<br />
assess PWWF based on results.<br />
Modify existing Blackbum WWTP<br />
to operate as storage basins.<br />
Route all flow to Lansdowne Road<br />
WWTP.<br />
Pipeline route (m m m) from <strong>Blackburn</strong><br />
storage basins to Correctional<br />
Centre tie-in.<br />
Assess conditionlcapacity of existing<br />
Mackus Road PS.<br />
Assess conditionlcapacity of existing<br />
sewage conveyance system through<br />
downtown area.<br />
Assess impact of added sewage<br />
flow on Lansdowne Road WWTP<br />
capacityloperation.<br />
I.<br />
I/<br />
I.<br />
li<br />
i I<br />
!<br />
LEGEND:<br />
! ------ Exist. Sanitary Collection Mains<br />
Blackbum Sanitary Collection Area<br />
City of Prince George<br />
<strong>Blackburn</strong> <strong>Wastewater</strong> <strong>Treatment</strong> <strong>Plant</strong><br />
<strong>Treatment</strong> Options <strong>Study</strong><br />
OPTION 3<br />
Figure 4.3
Section 4.0 - Blackbum <strong>Treatment</strong> Options<br />
Condition and capacity of the existing Mackus Road pumpstation must be<br />
evaluated.<br />
Details for pipeline routes for transferring Blackbum sewage flows to<br />
Lansdowne Road WWTP must be evaluated.<br />
Ammonia toxicity issue addressed at Lansdowne Road WWTP.<br />
4.3.2 Design Information<br />
Population<br />
ADWF, m3/d<br />
PWWF, m3/d<br />
Pipework<br />
Gravity sewermain from the existing Blackbum WWTP site to<br />
the Regional Correctional Centre tie-in<br />
Diameter, mm<br />
Length, m<br />
Sanitary sewer syphon from Yellowhead Bridge connecting to<br />
downtown sewage collection system<br />
Diameter, rnrn<br />
Length, m<br />
Gravity sewer to intersection of 15' Ave. and Taylor Drive;<br />
construct new manhole<br />
Diameter, mm<br />
Length, m<br />
Gravity sewer along 1 5 Ave. ~ from Taylor Drive to Birch St.;<br />
connect to 525 diameter sewer<br />
Diameter, rnm<br />
Length, m<br />
Pumpstation<br />
<strong>Upgrade</strong> Mackus Road PS for PWWF capacity<br />
MisceIlaneous<br />
Modifications to Blackbum WWTP to operate as storage basin<br />
4.3.3 Cost Estimate<br />
Pipework<br />
200 syphon, $200/m<br />
300 gravity sewer<br />
Blackbum, $160/m<br />
Downtown, $250/m<br />
Pumpstation<br />
Mackus Road PS, LS
Section 4.0 - <strong>Blackburn</strong> <strong>Treatment</strong> Options<br />
Miscellaneous<br />
Blackbum WWTP modifications to allow lagoons<br />
to operate as storage basins, LS 100,000<br />
Subtotat 1,165,000<br />
Contingencies (1 5 percent)<br />
EngineeringlAdminisWion (20 percent)<br />
GST (3 percent)<br />
TOTAL<br />
4.4 OPTION 4 - TRANSFER ALL FLOW < 2*ADWF TO LANSDOWNE<br />
ROAD WWTP AND USE THE EXISTING BLACKBURN WWTP TO<br />
TREAT FLOWS > 2*ADWF<br />
4.4.1 Outline<br />
In this option all flows up to 2*ADWF would be transferred &om the<br />
<strong>Blackburn</strong> sewage collection area for treatment at the Lansdowne Road<br />
WWTP. The existing sewage lagoons would be used only to treat wet weather<br />
flows > 2*AI)WF. A schematic representation of this option is presented in<br />
Figure 4.4. An It1 reduction program is to be i~tiated and completed to reduce<br />
the volume of wastewater being treated in the lagoons during wet weather and<br />
snowmelt conditions. The existing Mackus Road pumpstation would be<br />
upgraded and a new purnpstation constmcted to handle excess flow<br />
>2*ADWF. It is believed that the Lansdowne Road WWTP has sufficient<br />
capacity to handle the projected future 2*ADWF hydraulic and BODjtTSS<br />
loadings fkom the Blackbum sewage collection area. All wet weather flow ><br />
2*ADWF will be pumped to the existing Blackbum WWTP for treatment.<br />
Key activities or capitat works associated with this option are as follows:<br />
Implement VI reduction program.<br />
<strong>Upgrade</strong> Mackus Road purnpstation to handle project4 increased flows.<br />
All dry weather flows < 2'ADWF are to be pumped to Lansdowne Road<br />
WWTP; all wet weather flows > 2*ADWF are to be pumped to <strong>Blackburn</strong><br />
WWTP.<br />
Construct trunk gravity sewer and/or forcemain to transfer all flows<br />
Initiate Ill reduction program and<br />
complete over 5110 year period;<br />
assess PWWF based on results.<br />
0 Maintain existing <strong>Blackburn</strong> WWTP<br />
for flows > 2(ADWF).<br />
Route Rows s 2(ADWF) to Lansdowne<br />
Road WIKTP.<br />
Pipeline route (<br />
m) from<br />
Mackus Road PS to Correctional<br />
Centre tiein.<br />
Route flow > 2(ADWF) to <strong>Blackburn</strong><br />
WWTP using existing pipeline;<br />
provide primary treatment and<br />
discharge to Fraser River.<br />
Road<br />
Assess conditionlcapacity of existing<br />
Mackus Road PS; provide PS to pump<br />
flows > 2(ADWF) to <strong>Blackburn</strong> WWTP.<br />
Assess conditionlcapacity of existing<br />
sewage conveyance system through<br />
downtown area.<br />
Assess impact of added 2(ADWF)<br />
sewage flow on Lansdowne Road<br />
WWTP capacityloperation.<br />
I<br />
LEGEND:<br />
. - - - - - - Exist. Sanitary Collection Mains<br />
Blackbum Sanitary Collection Area<br />
City of Prince George<br />
Black ;bum <strong>Wastewater</strong> <strong>Treatment</strong> <strong>Plant</strong><br />
<strong>Treatment</strong> Options <strong>Study</strong><br />
OPTION 4<br />
Figure 4.4
Section 4.0 - Blackbm <strong>Treatment</strong> Options<br />
Key technical issues associated with this option are as follows:<br />
Extent to which the I/I reduction program is able to reduce peak wet<br />
weather flows must be evaluated.<br />
City must maintain operation of Blackbum WWTP; O&M costs associated<br />
with lagoon operation will not be significantly lower that for current<br />
operation.<br />
Expansion of the existing lagoons will not be required.<br />
Ammonia toxicity of lagoon emuent needs to be addressed.<br />
Major capital works required to transfer and proportion flows to<br />
Lansdowne Road WWTP and to <strong>Blackburn</strong> WWTP.<br />
Condition and capacity of the existing Mackus Road pumpstation must be<br />
evaluated.<br />
Details for pipeline routes for transferring Blackbum sewage flows to<br />
Lansdowne Road WWTP must be evaluated, as well as, pumping of wet<br />
weather flows to <strong>Blackburn</strong> WWTP.<br />
Ammonia toxicity issue partialIy addressed at Lansdowne Road WWTP for<br />
2*ADWF<br />
4.4.2 Design Information<br />
Population<br />
ADWF, m3/d<br />
PWWF, m3/d<br />
Pipework<br />
Forcemain fiom intersection of Mackus Road and North<br />
Blackbum Road to a high point on Hwy. 16<br />
Diameter, mm 200<br />
Length, m 1,720<br />
Gravity sewermain fiom the end of 200 diameter forcemain to<br />
the Regional Correctional Centre tie-in<br />
Diameter, mm 300<br />
Length, m 3,100<br />
Sanitary sewer syphon from Yellowhead Bridge connecting to<br />
downtown sewage collection system<br />
Diameter, mrn 200<br />
Length, m 100
Section 4.0 - <strong>Blackburn</strong> <strong>Treatment</strong> Options<br />
Gravity sewer to intersection of 15" Ave. and Taylor Drive;<br />
construct new manhole<br />
Diameter, mrn 300<br />
Length, m 100<br />
Gravity sewer along 15' Ave. from Taylor Drive to Birch St.;<br />
connect to 525 diameter sewer<br />
Diameter, mm 300<br />
Length, m 180<br />
Pumpstation<br />
<strong>Upgrade</strong> Mackus Road PS for 2*AD WF capacity<br />
w<br />
Supply and install PS and construct overflow wet well to handle<br />
flows > 2 * m<br />
Miscellaneons<br />
Modifications to existing BIackbwn WWTP to provide primary<br />
treatment for flows > 2*ADWF<br />
4.4.3 Cost Estimate<br />
Pipework<br />
200 forcemain, $180/m<br />
w 200 syphon, $200/m<br />
300 gravity sewer<br />
<strong>Blackburn</strong>, $l6O/m<br />
Downtown, $250/m<br />
Pumpstation<br />
Mackus Road PS, LS<br />
Mackus Road Overflow PS, LS<br />
Miscellaneous<br />
Blackbum WWTP modifications, LS<br />
Subtotal<br />
Contingencies (1 5 percent)<br />
Engineering/Adminishtion (20 percent)<br />
GST (3 percent)<br />
TOTAL<br />
4.5 OPTION 5 - TRANSFER ALL FLOW < 2*ADWF TO LANSDOWNE<br />
ROAD W TP AND USE THE EXISTING BLACKBURN WWTP TO<br />
TREAT FLOWS > 2*ADWF<br />
4.5.1 Outline<br />
In this option all flows up to 2*ADWF would be transferred from the<br />
<strong>Blackburn</strong> sewage collection area for treatment at the Lansdowne Road<br />
WWTP. The existing sewage lagoons would be used only to treat wet weather
Section 4.0 - Blackbum <strong>Treatment</strong> Options<br />
flows > 2*ADWF. A schematic representation of this option is presented in<br />
Figure 4.5. An VI reduction program is to be initiated and completed to reduce<br />
the volume of wastewater being treated in the lagoons during wet weather and<br />
snowmelt conditions. The existing Mackus Road purnpstation would be<br />
upgraded and modifications constructed at the <strong>Blackburn</strong> WWTP to handle<br />
excess flow >2*ADWF. It is believed that the Lansdowne Road WWTP has<br />
sufficient capacity to handle the projected future 2*ADWF hydraulic and<br />
BODOS loadings hm the Blackbum sewage collection area. All wet<br />
weather flow > 2*ADWF will be diverted to the existing Blackbum WWTP<br />
for treatment.<br />
Key activities or capital works associated with this option are as follows:<br />
Implement VI reduction prbgram.<br />
<strong>Upgrade</strong> Mackus Road purnpstation to handle projected increased flows.<br />
Construct trunk gravity sewer to transfer dry weather flow from Blackbum<br />
sewerage area to Lansdowne Road WWTP.<br />
<strong>Upgrade</strong> downtown sewage collection system to handle 2*AD\VF h m<br />
Blackbum sewerage area.<br />
Key technical issues associated with this option are as follows:<br />
Extent to which the I/l reduction program is able to reduce peak wet<br />
weather flows must be evaluated.<br />
City must maintain Blackbum WWTP; O&M costs associated with lagoon<br />
operation will not be significantly lower than for current operation.<br />
0 Expansion of the existing lagoons will not be required.<br />
Ammonia toxicity of lagoon effluent needs to be addressed.<br />
Major capital works needed to transfer flows to Lansdowne Road WWTF'.<br />
0 Condition and capacity of the existing Mackus Road pumpstation must be<br />
evaluated.<br />
Details for pipeline routes for transferring Blackbum sewage flows to<br />
Lansdowne Road WWTP must be evaluated, as well as modifications<br />
required to divert wet weather flows to Blackbum WWTP.<br />
Ammonia toxicity issue partially addressed at Lansdowne Road WWTP.
Initiate Ill reduction program and<br />
complete over 5110 year period;<br />
assess PWWF based on results.<br />
0 Maintain existing <strong>Blackburn</strong> WWTP<br />
for flows > 2(ADWF).<br />
Route all flow to <strong>Blackburn</strong> WWTP<br />
using existing pipeline.<br />
Route flows s 2(ADWF) to Lansdown<br />
Road WWTP for treatment.<br />
Pipeline route (= =) from Blackbun<br />
WWTP to Correctional Centre tie-in.<br />
8 Provide primary treatment for flows<br />
> 2(ADWF) at Blackbum WWTP and<br />
discharge to Fraser River.<br />
Assess conditionlcapacity of existin:<br />
Mackus Road PS.<br />
Assess conditionkapacity of existins<br />
sanitary conveyance system through<br />
downtown area.<br />
Assess impact of added 2(ADWF)<br />
sewage flow on Lansdowne Road<br />
WWTP capacityloperation.<br />
LEGEND:<br />
. - - - - - - Exist. Sanlary Collection Mains<br />
Blackbum Sanitary Collectjon Area
Section 4.0 - Blackbum <strong>Treatment</strong> Options<br />
4.5.2 Design Information<br />
Population<br />
ADWF, m3/d<br />
PWWF, m3/d<br />
Pipework<br />
Gravity sewermain from the existing Blackbum WWTP site to<br />
the Regional Correctional Centre tie-in<br />
Diameter, mm<br />
Length, m<br />
Sanitary sewer syphon connecting to downtown sewage<br />
collection system<br />
Diameter, mm<br />
Length, m<br />
Gravity sewer to intersection of l5Ih Ave. and Taylor Drive;<br />
construct new manhole<br />
Diameter, mm<br />
Length, m<br />
Gravity sewer along 15'~ Ave. hm Taylor Drive to Birch St.;<br />
connect to 525 diameter sewer<br />
Diameter, mm<br />
Length m<br />
Pumpstation<br />
<strong>Upgrade</strong> Mackus Road PS for 2*ADWF capacity<br />
Miscellaneous<br />
4.5.3 Cost Estimate<br />
Modifications to existing Blackbum WWTP to provide primary<br />
tre-ent for flows > 2*ADWF<br />
Pipework<br />
200 syphon, $200/m<br />
300 gravity sewer<br />
Blackbm, $160/m<br />
Downtown, $250/m<br />
Pumpstation<br />
Mackus Road PS, LS<br />
Miscellaneous<br />
Btackburn WWTP modifications, LS<br />
Subtotal<br />
Contingencies (15 percent)<br />
Engineering/ Administration (20 percent)<br />
GST (3 percent)<br />
TOTAL
Section 4.0 - Blackbum <strong>Treatment</strong> Options<br />
4.6 OPTION 6 - UPGRADE AND EXPAND BLACKBURN WWTP TO<br />
TREAT PROJECTED FLOWS AND LOADS<br />
4.6.1 Outline<br />
In this option the existing sewage lagoons would be upgraded and expanded to<br />
handle projected flows and loads from the <strong>Blackburn</strong> sewage collection area,<br />
for an ultimate population of 5,000 persons, and to meet required effluent<br />
standards. The existing treatment system consists of two aerated lagoons,<br />
sized to accommodate a contributing population of 2,500. Expanding the<br />
lagoon system to handle the ultimate population of 5,000 would involve<br />
doubling its present size. The expanded lagoon system will address<br />
conventional treatment requirements for BODs and TSS removal. However,<br />
the lagoon system must also ahress removal of ammonia toxicity. Because of<br />
the winter and early spring weather conditions experienced in the Prince<br />
George area, it is practically impossible to achieve ammonia removal by<br />
nitrification in an aerated lagoon system. The issue of ammonia toxicity<br />
removal would have to be addressed by considering the addition of a tertiary<br />
rotating biological contactor (RBC) process to provide nitrification of the<br />
lagoon emuent. A schematic representation of this option is presented in<br />
Figure 4.6. An VI reduction program is to be implemented to reduce the<br />
volume of wastewater being treated in the lagoons during wet weather and<br />
snowmelt conditions. The existing Mackus Road pumpstation would be<br />
upgraded.<br />
Key activities or capital works associated with this option are as follows:<br />
Implement I/I reduction program.<br />
Rehabilitate existing lagoons.<br />
Double lagoon capacity.<br />
<strong>Upgrade</strong> Mackus Road pumpstation to handle projected increased flows.<br />
Address ammonia toxicity issue by considering the use of a tertiary<br />
nitrifying RBC.<br />
Key technical issues associated with this option are as follows:<br />
Extent to which the VI reduction program will reduce peak wet weather<br />
flows must be evaluated.
CITY OF PRINCE GEORGE<br />
Scale= $:I00<br />
f<br />
Existing Chlorine<br />
Contact Tank<br />
Initiate Ill reduction program and<br />
complete over 5/10 year period;<br />
assess PWWF based on results.<br />
0 <strong>Upgrade</strong> and expand Blackbum<br />
WWTP lagoon facility; provide<br />
treatment capability for ammonia<br />
reduction to address toxicity concerns.<br />
No routing of flow to Lansdowne Road<br />
WWT P.<br />
Assess conditionlcapacity of existing<br />
Mackus Road PS.<br />
Existing<br />
Operations<br />
Building<br />
lsM<br />
ENGINEERING LIMITED<br />
City of Prince George<br />
<strong>Blackburn</strong> <strong>Wastewater</strong> <strong>Treatment</strong> Planl<br />
<strong>Treatment</strong> Options <strong>Study</strong><br />
OPTION 6<br />
Figure 4. t
Section 4.0 - Blackbum <strong>Treatment</strong> Options<br />
* The City must maintain the Blackbum WWTP; O&M costs associated with<br />
expanded lagoon operation will be higher than for current operation.<br />
Additional land area must be identified if further expansion is<br />
contemplated.<br />
Ammonia toxicity of the lagoon effluent needs to be addressed.<br />
Incorporation of a tertiary nitrification stage will significantly increase the<br />
capital and O&M costs of the facility.<br />
The issue of whether nitrification can reliably be achieved in an add-on<br />
RBC process at temperatures below P C needs further investigation.<br />
No transfer of flows and loads, or ammonia toxicity issue to Lansdowne<br />
Road WWTP.<br />
Existing excess capacity at the Lansdowne Road WWTP would not be<br />
utilized.<br />
Condition and capacity of the existing Mackus Road pumpstation must be<br />
evaluated.<br />
4.6.2 Design Information<br />
Population<br />
ADWF, m3/d<br />
P W , m3/d<br />
Stage 1 (existing)<br />
Lagoon l (primary)<br />
Number<br />
Volume, m3<br />
FRT (@ ADWF = 900 m3/d), d<br />
Lagoon 2 (secondary)<br />
Number<br />
Volume, m3<br />
HRT (@ ADWF = 900 m3/d), d<br />
Aeration Blowers<br />
Number<br />
Power, hp<br />
Stage 2 (expanded)<br />
Lagoon 1MlB (primary)<br />
Number<br />
Volume, in3
Section 4.0 - Blackbum <strong>Treatment</strong> Options<br />
HRT (@ ADWF = 1,750 m3/d), d<br />
Lagoon 2N2B (secondary)<br />
Number<br />
Volume, rn3<br />
HRT (@ ADWF = 1,750 m3/d), d<br />
0 Aeration Blowers<br />
Number<br />
Power, hp<br />
Headworks<br />
According to original design data presented on AESL as-built drawing 4102-<br />
01-S-102, the influent works (channels and screens) are adequately sized to<br />
accommodate Stage 2 flows. No major modifications are required in this area.<br />
Aerated Lagoons<br />
The aerated lagoon system will need to be twinned to accommodate the design<br />
ADWF of 1,750 m3/d. Construction work involves the following:<br />
Excavation of two lagoons to the east of the existing two. The dimensions<br />
will be identical to the existing lagoons. The total volume to be excavated<br />
is approximately 23,000 m3. It is assumed some of the excavated material<br />
can be used to extend the berm and no material needs to be imported to<br />
complete construction.<br />
Replacement of both existing 60 hp aeration blowers. Depending on the<br />
mode of operation, the plant presently requires either 1 or both blowers<br />
running; series operation requires 60 hp, and parallel requires 120 hp. Stage<br />
2 requires 150 hp for series and 225 hp for parallel. There is presently<br />
room for three blowers in the existing building. Assuming present<br />
operating practice of no standby capacity during parallel operation is<br />
maintained, three 75 hp (nominal) aeration blowers will be required.<br />
Duplication of the air distribution system (34 "aeration guns" in each<br />
lagoon for a total of 68 new units). If is assumed the air distribution<br />
pipework will be mirrored.<br />
Additional emuent and drain piping will be required to connect the new<br />
lagoons to the chlorine contact chamber. The chlorine contact chamber is<br />
adequate for Stage 2 flows. It is assumed the new emuent pipework will be<br />
of similar configuration to the existing, with approximately 350 m of 300<br />
mm pipe, 2 manholes, and 3 concrete chambers.
Section 4.0 - Blackbum <strong>Treatment</strong> Options<br />
Nitrifying RBCs<br />
The above aerated lagoon system will be unable to produce a nitrified effluent.<br />
Therefore, if ammonia removal is required, a mechanical process such as a<br />
rotating biological contactor (RBC) must be added to treat the lagoon effluent<br />
to reduce the levels of ammonia. The process would be smaller than one<br />
needed to treat raw wastewater, as the organic loads in the lagoon emuent are<br />
significantly reduced.<br />
An RBC consists of a series of discs on which a fixed film of biological<br />
material is grown and maintained. The discs are mounted on a driveshaft,<br />
which rotates the discs through the wastewater. Oxygen is transferred to the<br />
biomass from the atmosphere during the time that the disc is out of the<br />
wastewater.<br />
An RBC can be hydraulically loaded at 0.03 - 0.08 m3/m2/d for combined BOD<br />
removal and nitrification. For separate nitrification, the hydraulic loading can<br />
be increased slightly to 0.04 - 0.10 m3/m2/d. To treat the anticipated ADWF of<br />
1,750 m3/d, approximately 16,700 m2 of media is required.<br />
At wastewater temperatures below 12S°C, the size of the RBC must be<br />
adjusted to achieve the same levels of performance. If the wastewater<br />
temperature is as low as 4OC (lagoon effluent could conceivably be lower in<br />
this climate), the area of the media must be increased by a factor of at least 2.5.<br />
Therefore a total area required to achieve nitrification at 4OC is in the order of<br />
42,000 m2. As the wastewater spends upwards of 20 days in a relatively<br />
shallow lagoon, the temperature of the effluent entering the RBC during the<br />
coldest periods is likely to approach 0°C. The surface area correction curves<br />
for media, below 4OC are quite steep, and it appears impractical to size an R3C<br />
in this temperature range.<br />
Nitrifying RBC<br />
Hydraulic loading rate, m3/m2/d<br />
Temperature correction factor<br />
Surface area, m2<br />
Without temperature correction<br />
With temperature correction<br />
Number<br />
Disc diameter, m
Section 4.0 - Blackbum <strong>Treatment</strong> Options<br />
4.6.3 Cost Estimate<br />
Lagoon System Without RBCYs<br />
Sitework<br />
Excavationberm construction, LS<br />
Manholes/chambers/pipes, LS<br />
Equipment<br />
Headworks, lagoons, chambers, LS<br />
Mechanical<br />
Headworks, lagoons, chambers, LS<br />
ElectricallInstrumeotation<br />
Headworks, lagoons, chambers, LS<br />
MisceUaneous<br />
Pumpstation<br />
Mackus Road PS, LS<br />
Subtotal<br />
Contingencies (15 percent)<br />
Engineering/Administration (20 percent)<br />
GST (3 percent)<br />
Total (without RBC)<br />
Lagoon System with RBC's for Nitrification<br />
The following listing of costs is the extra capital cost requird to include a<br />
nitrifiying R8C process at lagoon effluent temperature of 4OC.<br />
Structural<br />
TanklFRP covers, LS<br />
Equipment<br />
RBC's<br />
Mechanical<br />
Interconnecting pipework, etc.<br />
ElectricallInstrumeotation<br />
RBC motors and controls<br />
Miscellaneous<br />
Subtotal @BC)<br />
Subtotal (Lagoons)<br />
Contingencies (15 percent)<br />
Engineering/Administration (20 percent)<br />
GST (3 percent)<br />
Total (with RBC)
Section 4.0 - Blackbum <strong>Treatment</strong> Options<br />
When compared to the use of lagoons only, the inclusion of nitrifying RBCs<br />
into the process train increases the capital cost of this option by approximately<br />
$1 .O M, or 75 percent.<br />
4.7 OPTION 7 - DECOMMISSION EXISTING BLACKBURN WWTP AND<br />
REPLACE WITH A NEW SECONDARY TREATMENT PLANT<br />
4.7.1 Outline<br />
In this option the existing sewage lagoons would be decommissioned and<br />
replaced with a new secondary wastewater treatment plant with an ultimate<br />
design population of 5,000 persons. It is expected that conventional secondary<br />
treatment technology (either extended aeration, RSCs or SBRs) would be<br />
required. For the purpose -of this analysis, it has been assumed that a<br />
conventional activated sludge process will be used to achieve BODS and TSS<br />
removal. The issue of ammonia toxicity would be addressed by incorporating<br />
year-round nitrification into the process design using an extended aeration<br />
oxidation ditch process. A schematic representation of this option is presented<br />
in Figure 4.7. An yI reduction program is to be implemented to reduce the<br />
volume of wastewater being treated during wet weather and snowmelt<br />
conditions. The existing Mach Road pumpstation would be upgraded.<br />
Key activities or capital works associated with this option are as follows:<br />
Implement VI reduction program.<br />
Decommission Blackbum sewage lagoons and replace with new<br />
mechanical wastewater treatment plant.<br />
<strong>Upgrade</strong> Mackus Road pumpstation to handle projected flows.<br />
Address ammonia toxicity issue by incorporating nitrification into the<br />
process design.<br />
Key technical issues associated with this option are as follows:<br />
Extent to which the I/I reduction program will reduce peak wet weather<br />
flows must be evaluated.<br />
City must maintain the Blackbum WWTP; capital and O&M costs<br />
associated with a new mechanical plant at Blackbum will be significantly<br />
greater than for current lagoon operation.
:ITY Of PRINCE GEORGE<br />
Existing Chlorine<br />
Contact Tank<br />
Initiate UI reduction program and<br />
complete over 5110 year period;<br />
assess PWWF based on results.<br />
0 Decommission exisitng <strong>Blackburn</strong><br />
WWTP and restorellandscape site as<br />
required.<br />
Sludge Storage<br />
I<br />
7 (<br />
T,<br />
Secondary Clarifiers<br />
a Replace lagoon system with new<br />
secondary treatment plant; evaluate<br />
SBR, RBC and extended aeration<br />
process; provide treatment<br />
capability for ammonia reduction to<br />
address toxicity concerns.<br />
No routing of flow to Lansdowne<br />
Road WWTP.<br />
Asses conditionlcapacity of existing<br />
Mackus Road PS.<br />
Anoxic delector<br />
I<br />
,-- Concrete<br />
Ditch<br />
Existing Lagoons<br />
- Existing Operations Building<br />
(clw New Screens, Blowem)<br />
City of Prince George<br />
<strong>Blackburn</strong> <strong>Wastewater</strong> <strong>Treatment</strong> Plan!<br />
<strong>Treatment</strong> Options <strong>Study</strong><br />
ENGINEERING LIMITED<br />
OPTION 7<br />
Figure 4. i
Section 4.0 - <strong>Blackburn</strong> <strong>Treatment</strong> Ootions<br />
Proposed mechanical treatment plant will be more reliable in achieving<br />
nitrification than lagoodRJ3C combination.<br />
The incorporation of nitrification into the process design will significantly<br />
increase capital cost and marginally increase O&M costs.<br />
No transfer of flows and loads, or ammonia toxicity issue to Lansdowne<br />
Road WWTF'.<br />
Existing excess capacity at the Lansdowne Road WWTP would not be<br />
utilized.<br />
Condition and capacity of the existing Mackus Road pumpstation must be<br />
evaluated.<br />
4.7.2 Design Information<br />
Population<br />
ADWF, m3/d<br />
PWWF, m3/d<br />
Preliminary <strong>Treatment</strong><br />
Preliminary treatment removes coarse soli ds from the incoming wz tewater,<br />
which has a deleterious effect on downstream processes (pump clogging,<br />
abrasion, etc). At the very minimum, fme screening is required in front of a<br />
secondary process to remove bulky solids, and other inorganic materials. Grit<br />
removal is sometimes included, but the proposed secondary process (oxidation<br />
ditch) does not absohtely require it.<br />
The existing screening room has three channels: two 600 mm channels (one<br />
equipped with a 75 mm trash rack, one bypass) and a central 450 mm channel<br />
with a cornminutor. A mechanically cleaned screen can be installed into one<br />
of the 600 mm channels.<br />
Number<br />
Opening size, mm<br />
ADWF, Us<br />
Velocity through screen @ ADWF, mfs<br />
Depth of flow, rnm<br />
Width of channel (min), mm
Section 4.0 - Blackbum <strong>Treatment</strong> Options<br />
Secondary <strong>Treatment</strong><br />
Secondary activated sludge processes involve aeration basin(s) and clarifiers.<br />
<strong>Wastewater</strong> enters the basins where it is aerated and mixed with a population<br />
of preconditioned microorganisms. Soluble organic material is removed from<br />
the wastewater by biological oxidation, and the insoluble material is removed<br />
by physical entrapment and adsorption within the floc. This mixture of<br />
microorganisms and organic matter is called mixed liquor suspended solids, or<br />
activated sludge. AAer leaving the aeration basin, the mixed fiquor is<br />
separated into a clear supernatant fraction (secondary effluent) and settled<br />
solids (return activated sludge). The return activated sludge is pumped back to<br />
the aeration basin and mixed with the raw influent to maintain the microbial<br />
population. The solids retentmn time (SRT) or sludge age, is controlled by<br />
daily wasting a fraction of either the mixed liquor or the return activated<br />
sludge. This serves to offset excessive microbial growth in the aeration basin.<br />
Conventional activated sludge processes are designed solely for BOD and TSS<br />
reduction; an hydraulic retention time of only 7 h, and a sludge age of 4 to 7 d<br />
are required for this. If ammonia toxicity in the effluent is an issue, the<br />
retention times must be increased to foster nitrification, which is the<br />
conversion of ammonia to nitrites and nitrates. Organisms, which perform this<br />
reaction generally, grow at a slower rate. This modification is called extended<br />
aeration, and involves doubling the hydraulic and solids retention times. A<br />
small non-aerated compartment known as an anoxic selector is usually<br />
included at the inlet to the aeration tank. This environment favours the growth<br />
of flac-forming organisms over filamentous organisms, which enhance the<br />
settleability of the mixed liquor, which in turn improves the quality of the<br />
secondary effluent. In addition, it reduces some of the nitrates produced in the<br />
nitrification reaction. Nitrates are converted to dissolved nitrogen, which<br />
evolves as nitrogen gas to the atmosphere.<br />
In the event that primary treatment is not included, the secondary treatment<br />
parameters described above would require further increase by a factor of<br />
approximately 1.5 to 2.0. A process flow diagram of the activated sludge<br />
process as it may be applied at this site is described below. Screened<br />
wastewater is combined with return activated sludge and enters an anoxic cell,<br />
which in turn discharges to an oxidation ditch equipped with fine bubble<br />
diffusers and mixers to drive the flow around the circuit. Due to the absence of<br />
primary clarifiers, the oxidation ditch will be sized for a hydraulic retention<br />
time of 24 h to ensure nitrification. The mixed liquor then flows to two<br />
secondary clarifiers, each sized for 50 percent of the total flow. Emuent from
Section 4.0 - <strong>Blackburn</strong> <strong>Treatment</strong> Options<br />
the clarifier discharges directly to the river. The settled sludge is pumped back<br />
to the aeration basins at a rate approximately equal to the influent ADWF.<br />
Excess sludge is wasted from the return activated sludge and diverted to a vault<br />
where it is allowed to settle further. The supernatant from this vault is decanted<br />
back to the plant headworks. Thickened sludge is transported off-site for<br />
disposal.<br />
Non-nitrifying bioreactor<br />
HRT, h<br />
SRT, d<br />
Anoxic cells<br />
Volume (anoxic cell), m3<br />
Power (anoxic cell mixer)!hp<br />
Aerobic cells<br />
Volume (aerobic cell), m3<br />
Plan dimensions, m<br />
SWD,m<br />
MLSS, mglL 2,200<br />
Type of aeration<br />
Blowers<br />
Power (aeration blowers), hp<br />
fine bubble dif!%sers<br />
2<br />
40<br />
Mixers (aerobic cell)<br />
Power (aerobic cell mixers), hp<br />
Waste activated sludge storage<br />
Waste RAS (@ 8,000 ma), m3fd<br />
WAS storage capacity, d<br />
Volume (WAS tank), m3<br />
Plan dimensions, m<br />
SWD,m<br />
WAS tank aerator<br />
Power (tank aerator), hp<br />
Secondary Clarifiers<br />
Secondary clarification is required to remove the bulk of solids !?om the mixed<br />
liquor before final discharge, and to return the separated biological solids to the<br />
bioreactor. The secondary clarifiers will be sid to process 50 percent of<br />
ADWF each at a relatively low overflow rate, thereby allowing one to be taken
Section 4.0 - Blackbum <strong>Treatment</strong> Options<br />
out of senice for maintenance and emergencies while allowing the other to<br />
perform adequately. Only one clarifier would be provided at first; the second<br />
would be installed when flows and populations warrant.<br />
Secondary Clarifier<br />
Clarifiers<br />
Overflow rate, m3/m2/d<br />
Surface area, m2<br />
Diameter, rn<br />
SWD,m<br />
2 (1 now; 1 future)<br />
10<br />
85<br />
10<br />
4.0<br />
RAS Pumps<br />
b p s<br />
Capacity, Lls<br />
TDH,m<br />
Power, hp<br />
Nitrifying Activated Sludge Process<br />
The above activated sludge process will not be able to produce a nitrified<br />
effluent. If nitrification is required, the HRT of &he bioreactor will have to be<br />
increased to approximately 24 h by increasing the volume from 500 m' to<br />
1,700 m3. The ancillary processes included with this option with nitrification<br />
are essentially identical to those described above, i.e. the headworks,<br />
secondary clarifiers, etc. will be the same size. The mechanical components<br />
(mixers, pumps, etc) should be of similar size and quantity. The aeration<br />
system, however, will be larger to meet the oxygen requirements for<br />
nitrification. The blowers will be more powerful and the size of the aeration<br />
diffuser grids will be increased proportionally.<br />
The major cost increase will be in construction costs rather than mechanical<br />
furnishings. The amount of excavation, concrete, and other structural elements<br />
required for the bioreactor will be increased by a factor of at least two.<br />
Nitrifying Bioreactor<br />
HRT,h<br />
SRT,d<br />
Anoxic cells<br />
Volume (anoxic selector cell) m3<br />
Power (anoxic cell mixer), hp<br />
Aerobic cells
Section 4.0 - Blackbum <strong>Treatment</strong> Options<br />
Volume (aerobic cells), m3<br />
Plan dimensions, rn<br />
SWD,m<br />
Type of aeration<br />
Blowem<br />
Power (aeration blower), hp<br />
fine bubble diffusers<br />
2<br />
60<br />
Mixers<br />
Power (mixers), hp<br />
4.7.3 Cost Estimate<br />
Conventional activated sludge plant<br />
Sitework<br />
Excavation, preparation, backfill, etc. LS<br />
Structural<br />
HeadworMlower bldgJsludge vault, LS<br />
Bioreactor, LS<br />
Clarifiers,LS<br />
Equipment<br />
Headworkshlower bldg./sludge vault, LS<br />
Bioreactor, LS<br />
Clarifiers,LS<br />
Mechanical<br />
Headworkshlower bldg./sludge vault, LS<br />
Bioreactor, LS<br />
Clarifiers, LS<br />
ElectricaVInstmmentation<br />
Headworks/blower bldg./sludge vault, LS<br />
Bioreactor, LS<br />
Clarifiers, LS<br />
Miscellaneous, LS<br />
Pumpstation<br />
Makus Road PS, LS<br />
Subtotal<br />
Contingencies (15 percent)<br />
EngineeringtAdministration (20 percent)<br />
GST (3 percent)<br />
Total
Section 4.0 - Blackbum <strong>Treatment</strong> Options<br />
Extended Aeration <strong>Plant</strong><br />
Sitework<br />
Excavation, preparation, backfill, etc., LS<br />
Structural<br />
Headworks/blower bldg./sludge vault, LS<br />
Bioreactor, LS<br />
Clarifiers, LS<br />
Equipment<br />
Headworkshlower bldg.lsludge vault, LS<br />
Bioreactor, LS<br />
Clarifiers, LS<br />
Mechanical<br />
Headworkslblower bldg.ls1udge vault, LS<br />
Bioreactor, LS<br />
Clarifiers,LS<br />
ElectricallInstrumentation<br />
Headworkdblower bldg./sludge vault, LS<br />
Bioreactor, LS<br />
Clarifiers, LS<br />
MisceUaneous, LS<br />
Pumpstation<br />
Makus Road PS, LS<br />
Subtotal<br />
Contingencies (15 percent)<br />
EngineeringtAdministration (20 percent)<br />
GST (3 percent)<br />
Total<br />
When compared to the conventional activated sludge option, the incorporation<br />
of nitrification into the process design increases the capital cost of this option<br />
by over $0.5 M, or approximately 35 percent.<br />
4.8 LIFE CYCLE COST ANALYSIS<br />
Seven basic options were identified in the previous sections as being<br />
appropriate for evaluation. Two of the options, Options 6 and 7, are based on<br />
maintaining full secondary treatment at the Blackbum WWTP site. These two<br />
options have been further subdivided into Options 6a and 6b, and 7a and 7b,<br />
respectively, to address the issue of ammonia toxicity removal. Conceptual<br />
level costing has been developed for each of the options as well as detailed
Section 4.0 - Blackbum <strong>Treatment</strong> Options<br />
descriptions to assist with the decision making process. These seven basic<br />
wastewater treatment andor transfer options and the two sub-options will be<br />
evaluated against both economic and non-economic criteria.<br />
The non-economic analysis is described in Section 5.0, and was completed at<br />
the Decision Workshop held with City staff on October 19, 1999.<br />
The economic analysis is based on preliminary capital cost estimates and<br />
ongoing operating and maintenance (O&M) cost estimates for the above nine<br />
options. Estimates were also made of the approximate timing of the required<br />
capital expenditures. These values were used to generate 25-year life cycle<br />
wst estimates for the nine options using a net present value (NPV) analysis at<br />
a discount rate of 6 percent. :<br />
In all nine options, it was assumed that the major capital expenditure would<br />
occur in 200612007, so that the upgrades would be fully operational when the<br />
existing sewage lagoons at the Blackbum WWTP are at capacity. The existing<br />
lagoons will be operated until that time. Implicit in this assumption is that the<br />
L'I mitigation measures will be successhlly completed in the next five years.<br />
In all options involving the transfer of wastewater from the <strong>Blackburn</strong><br />
colIection area to the Lansdowne Road W P , which are Options 1 to 5, a<br />
small incremental O&M cost allowance was made for treating the additional<br />
wastewater at the Lansdowne Road WWTP. However, no allowance was<br />
made for the fact that this transfer may require & earlier upgrade at<br />
Landsdowe Road WWTP as the <strong>Blackburn</strong> sewage flows are less that 4<br />
percent of the existing capacity at Lansdowne Road WWTP, and the effect of<br />
such a small incremental increase is outside the accuracy of this analysis.<br />
The estimated capital and 25-year life cycle costs for the nine wastewater<br />
treatment options are presentd in Appendix B, and are summarized in Table<br />
4.1 below.<br />
TabIe 4.1: 25-year Life Cycle Costs
Section 4.0 - <strong>Blackburn</strong> <strong>Treatment</strong> Options<br />
Option<br />
7a<br />
7b<br />
Capital Cost<br />
1999<br />
1,785,000<br />
2,315,000<br />
NT'V<br />
Capital Cost<br />
1,155,000<br />
1,495,000<br />
NPV<br />
O&M Costs<br />
1,840,0000<br />
1,840,0000<br />
XPV<br />
Total<br />
2,995,000<br />
3,335,000<br />
The above life cycle cost summary shows that the NeV of Options 1,2, 3,4, 5,<br />
and 6a are all within approximately 20 percent of each other, with Option 2<br />
(decommission Blackbum WWTP and transfer all flows by gravity sewer to<br />
the Lansdowne Road WWTP) having the lowest overall cost. All options<br />
involving the installation of a mechanical secondary treatment plant at the<br />
<strong>Blackburn</strong> site (Options 6b, 7a and 7b) have a significantly higher cost than the<br />
flow transfer options.
SECTION 4<br />
WASTEWATER TREATMENT OPTIONS
SECTION 4.0<br />
BLACKBURN TREATMENT OPTIONS<br />
The following seven options have been identified for upgrading the <strong>Blackburn</strong><br />
sewage collection area and WWTP:<br />
4.1 OPTION 1 - DECOMMISSION EXISTING BLACKBURN WWTP AND<br />
ROUTE ALL FLOW TO LANSDOWNE ROAD WWTP MA<br />
FORCEMAINlGRAVITY SEWER CONNECTION<br />
4.1.1 Outline<br />
In this option the existing sewage lagoons would be decommissioned and all<br />
flows transferred for treatment at the Lansdowne Road WWTP via a new<br />
forcemain and trunk gravity sewer from the Mackus Road pumpstation. A<br />
schematic representation of this option is presented in Figure 4.1. An VI<br />
reduction program is to be initiated and completed to reduce the volume of<br />
wasfewater being transferred during wet weather and snowmelt conditions.<br />
The existing Mackus Road pumpstation would be upgraded and a new, small<br />
pumpstation would be constructed at the Blackbum WWTP site. It is believed<br />
that the Lansdowne Road WWTP has sufficient capacity to handIe the<br />
projected future hydraulic and BODflSS loadings from the Blackbum sewage<br />
collection area.<br />
Key activities or capital works associated with this option are as follows:<br />
Implement and complete I/I reduction program.<br />
Decommission lagoons and rehabilitate site for other use.<br />
<strong>Upgrade</strong> Mackus Road pumpstation to handle projected increased flows.<br />
Construct t ~nk gravity sewer and/or forcemain to transfer all flows from<br />
Blackbum sewerage area to Lansdowne Road WWTP.<br />
<strong>Upgrade</strong> downtown sewage collection pipework to handle increased flows<br />
from Blackbum sewerage area<br />
Construct sewage pumpstation at Blackbum WWTP site and construct<br />
connecting forcemain discharging to Mackus Road pumpstation.
1<br />
Initiate In reduction program and<br />
complete over 5/10 years;<br />
assess PWWF based on results.<br />
0 Decommission existing <strong>Blackburn</strong><br />
WWTP and restorellandscape site.<br />
a Route all flow to Lansdowne Road<br />
Pipeline route (8 8 rn 8) from Mackus<br />
Road PS to Correctional Centre tie-in.<br />
Pipeline route (8 8 rn .)from new PS at<br />
decommissioned <strong>Blackburn</strong> WWTP<br />
site to Mackus Road PS.<br />
a Assess conditionlcapacity of existing<br />
Mackus Road PS.<br />
downtown area.<br />
Assess impact of added sewage flow<br />
on Lansdowne Road WWTP<br />
capacityloperation.<br />
Exist. Sanitary Collection Mains<br />
Blackbum Sanitary Collection Area<br />
City of Prince George<br />
ckburn <strong>Wastewater</strong> <strong>Treatment</strong> <strong>Plant</strong><br />
<strong>Treatment</strong> Options <strong>Study</strong><br />
I
Section 4.0 - <strong>Blackburn</strong> <strong>Treatment</strong> Options<br />
Key technical issues associated with this option are as folIows:<br />
Extent to which the I/i reduction program is able to reduce peak wet<br />
weather flows must be evaluated.<br />
City need operate only one wastewater treatment and disposal facility.<br />
Major capital works needed to transfer flows to Lansdowne Road WWTP.<br />
Condition and capacity of the existing Mackus Road pumpstation must be<br />
evaiuated.<br />
Details for pipeline routes for transferring Blackbum sewage flows to<br />
Lansdowne Road WWTP must be evaluated.<br />
Impact of added flow on capacity/operation of Lansdowne Road WWTP<br />
needs to be evaluated.<br />
Ammonia toxicity issue addressed at Lansdowne Road WWTP.<br />
4.1.2 Design Information<br />
Population<br />
ADWF, m3/d<br />
PWWF, m3/d<br />
Pipework<br />
Forcemain from intersection of Mackus Road and North<br />
<strong>Blackburn</strong> Road to a high point on Hwy. 16.<br />
Diameter, mm<br />
Length, m<br />
Gravity sewer main from the end of 200 diameter forcemain to<br />
the Regional Correctional Centre tie-in<br />
Diameter, mm<br />
Length, m<br />
Forcemain from the existing <strong>Blackburn</strong> WWTP site to the high<br />
point on Graves Road<br />
Diameter, mrn<br />
Length, m<br />
Sanitary sewer syphon from Yellowhead Bridge connecting to<br />
downtown sewage collection system<br />
Diameter, mm<br />
Length, m<br />
Gravity sewer to intersection of l5Ih Ave. and Taylor Drive;<br />
construct new manhole
Section 4.0 - Blackbum <strong>Treatment</strong> O~tions<br />
Diameter, mm 300<br />
Length, m 100<br />
Gravity sewer along 15' Ave. from Taylor Drive to Birch Street;<br />
connect to 525 diameter sewer<br />
Diameter, mrn 300<br />
Length, m 180<br />
Pumpstation<br />
<strong>Upgrade</strong> Mackus Road PS for PWWF capacity<br />
Supply and install PS at existing Blackbum WWTP site to<br />
service residence along Graves and Foreman Roads; capable of<br />
pumping 10 percent of PWWF.<br />
Miscellaneons<br />
Restorellandscape existing Blackbum WWTP site.<br />
4.1.3 Cost Estimate<br />
Pipework<br />
150 forcemain, $100/m<br />
200 forcemain, $1 8Olm<br />
200 syphon, $200/m<br />
300 gravity sewer<br />
<strong>Blackburn</strong>, $160/m<br />
Downtown, S250lm<br />
Pumpstation<br />
Mackus Road PS, LS<br />
Foreman Road PS, LS<br />
Miscellaneous<br />
<strong>Blackburn</strong> WWTP site restorationflandscaping, LS<br />
Subtotal<br />
Contingencies (1 5 percent)<br />
Engineering/Administration (20 percent)<br />
GST (3 percent)<br />
TOTAL<br />
4.2 OPTION 2 - DECOMMISSION EXISTING BLACKBURN WWTP AND<br />
ROUTE ALL FLOW TO LANSDOWNE ROAD \ m P VIA GRAVITY<br />
SEWER CONNECTION<br />
4.2.1 Outline<br />
In this option the existing sewage lagoons would be decommissioned and all<br />
flows transferred for treatment at the Lansdowne Road WWTP via a new trunk<br />
gravity sewer. A schematic representation of this option is presented in Figure
Section 4.0 - Blackbum <strong>Treatment</strong> Options<br />
4.2. An H reduction program is to be initiated and completed to reduce the<br />
volume of wastewater being transferred during wet weather and snowmelt<br />
conditions. The existing Mackus Road pumpstation would be upgraded. It is<br />
believed that the Lansdowne Road WWTP has sufficient capacity to handle the<br />
projected future hydraulic and BOD5/TSS loadings from the Blackbum sewage<br />
collection area.<br />
Key activities or capital works assmiated with this option are as follows:<br />
Implement and complete VI reduction program.<br />
Decommission lagoons and rehabilitate site for other use.<br />
<strong>Upgrade</strong> Mackus Road pdpstation to handle projected increased flows.<br />
Construct trunk gravity sewer to transfer all flours hrn Blackbum<br />
sewerage area to Lansdowne Road WWTP.<br />
<strong>Upgrade</strong> downtown sewage collection pipework to handle increased flows<br />
from Blackbum sewerage area.<br />
Key technical issues associated with this option are as follows:<br />
Extent to which the VI reduction program is able to reduce peak wet<br />
weather flows must be evaluated.<br />
City need operate only one wastewater treatment and disposal facility.<br />
Major capital works needed to transfer flows to Lansdowne Road WWTP.<br />
Condition and capacity of the existing Mackus Road pumpstation must be<br />
evaluated.<br />
Details for pipeline routes for transferring Blackbum sewage flows to<br />
Lansdowne Road WWTP must be evaluated.<br />
Ammonia toxicity issue addressed at Lansdowne Road WWTP.<br />
4.2.2 Design Information<br />
Population<br />
ADWF, m3/d<br />
PWWE, m3/d
'IN - OF PRINCE GEORGE<br />
I<br />
Initiate Ill reduction program and<br />
complete over 5/10 year period;<br />
assess PWWF based on results.<br />
Decommission existing <strong>Blackburn</strong><br />
WWTP and restorellandscape site.<br />
a Route all flow to Lansdowne Road<br />
WWT P.<br />
Pipeline route (m m m) from Blackbum<br />
WWTP site to Correctional Centre tie-in.<br />
Assess conditionlcapacity of existing<br />
Mackus Road PS.<br />
a Assess conditionlcapacity of existing<br />
sewage conveyance system through<br />
downtown area.<br />
. . . . . - -<br />
~rin ~...<br />
, - ..c4 a Assess impact of added sewage flow<br />
citydf" .<br />
cg~- ~ed@e<br />
: / Road<br />
L ---- - . .<br />
on Lansdowne Road WWTP<br />
capacityloperation.<br />
.- ~<br />
..-. - --~<br />
LEGEND:<br />
------ Exist. Sanitary Collection Mains<br />
<strong>Blackburn</strong> Sanitary Collection Area<br />
City of Prince George<br />
ckburn <strong>Wastewater</strong> <strong>Treatment</strong> <strong>Plant</strong><br />
<strong>Treatment</strong> Options <strong>Study</strong><br />
OPTION 2<br />
ENGINEERING LIMITE; Figure 4.2<br />
I
Section 4.0 - Blackbum <strong>Treatment</strong> Options<br />
Pipework<br />
Gravity sewermain fiom the existing <strong>Blackburn</strong> WWTP site to<br />
the Regional Correctional Centre tie-in<br />
Diameter, mm<br />
Length, m<br />
Sanitary sewer syphon from Yellowhead Bridge connecting to<br />
downtown sewage collection system<br />
Diameter, mm<br />
m<br />
Gravity sewer to intersection of 1 5 Ave. ~ ~ and Taylor Drive;<br />
construct new manhole<br />
Diameter, mm<br />
Length, m<br />
Gravity sewer along 15Ih Ave. from Taylor Drive to Birch St.;<br />
connect to 525 diameter s&er<br />
Diameter, mm<br />
ten&, m<br />
Pumpstation<br />
<strong>Upgrade</strong> Mackus Road PS for P WWF capacity<br />
Miscellaneous<br />
Restore/landscape existing Blackbum WWTP site.<br />
4.2.3 Cost Estimate<br />
Pipework<br />
200 syphon, $200/m<br />
300 gravity sewer<br />
Blackbum, $160/m<br />
Downtown, $250/m<br />
Pumpstation<br />
Mach Road PS, LS<br />
Miscellaneous<br />
<strong>Blackburn</strong> WWTP site restorationtlandscaping, LS<br />
Subtotal<br />
Contingencies (1 5 percent)<br />
Engineering/Adrninistration (20 percent)<br />
GST (3 percent)<br />
TOTAL
Section 4.0 - Blackbm <strong>Treatment</strong> Options<br />
4.3 OPTION 3 - USE EXISTING BLACKBURN WWTP FOR<br />
EQUALIZATIONlSTORAGE AND TRANSFER ALL FLOWS TO<br />
LANSDOWNE ROAD WWTP<br />
4.3.1 Outline<br />
In this option the existing sewage lagoons would be converted to flow<br />
equalizationktorage basins, and all flows transferred for treatment at the<br />
Lansdowne Road WWTP. A schematic representation of this option is<br />
presented in Figure 4.3. The principal benefit of this option is that the peak<br />
flows being transferred from the <strong>Blackburn</strong> sewage wllection area to the<br />
Lansdowne Road WWTP would be attenuated somewhat. An VI reduction<br />
program is to be initiated and completed to reduce the volume of wastewater<br />
being transferred during wet weather and snowmelt conditions. The existing<br />
Mackus Road pumpstation would be upgraded. It is believed that the<br />
Lansdowne Road WWTP has sufficient capacity to handle the projected future<br />
hydraulic and BODflSS loadings from the <strong>Blackburn</strong> sewage wllection area.<br />
Key activities or capital works associated with this option are as follows:<br />
Implement L'l reduction program.<br />
0 Modify lagoons for use as flow equalizatiodstorage basins.<br />
0 <strong>Upgrade</strong> Mackus Road pumpstation to handle projected increased flows.<br />
Construct trunk gravity sewer to transfer all flows ihm <strong>Blackburn</strong><br />
sewerage area to Lansdowne Road WWTP.<br />
<strong>Upgrade</strong> downtown sewage collection system to handle increased flows<br />
from <strong>Blackburn</strong> sewerage area.<br />
Key technical issues assmiated with this option are as follows:<br />
Extent to which the I/I reduction program is able to reduce peak wet<br />
weather flows must be evaluated.<br />
City must maintain operation of storage basins; O&M costs of<br />
equalizatiodstorage basins are only slightly lower than O&M costs for the<br />
existing treatment lagoons.<br />
Major capital works needed to transfer flows to Lansdowne WWTP and<br />
modify lagoons.
Initiate Ill reduction program and<br />
complete over 5/10 year period;<br />
assess PWWF based on results.<br />
0 Modify existing <strong>Blackburn</strong> WWTP<br />
to operate as storage basins.<br />
a Route all flow to Lansdowne Road<br />
WWT P.<br />
Pipeline route (m m) from Blackbum<br />
storage basins to Correctional<br />
Centre tiein.<br />
Assess conditionlcapacity of existing<br />
Mackus Road PS.<br />
@ Assess conditionlcapacity of existing<br />
sewage conveyance system through<br />
downtown area.<br />
a Assess impact of added sewage<br />
flow on Lansdowne Road WWTP<br />
/Ti<br />
LEGEND:<br />
------ Exist. Sanitary Collection Mains<br />
Blackbum Sanitary Collection Area<br />
City of Prince George<br />
ckburn <strong>Wastewater</strong> <strong>Treatment</strong> <strong>Plant</strong><br />
<strong>Treatment</strong> Options <strong>Study</strong><br />
I<br />
OPTION 3<br />
Figure 4.3
Section 4.0 - Blackbum <strong>Treatment</strong> Options<br />
Condition and capacity of the existing Mackus Road pumpstation must be<br />
evaluated.<br />
Details for pipeline routes for transfening Blackbum sewage flows to<br />
Lansdowne Road WWTP must be evaluated.<br />
Ammonia toxicity issue addressed at Lansdowne Road WWTP.<br />
43.2 Design Information<br />
Population<br />
ADWF, m3/d<br />
PWWF, m3/d<br />
Pipework<br />
Gravity sewermain hm<br />
the existing Blackbum WWTP site to<br />
the Regional Correctional Centre tie-in<br />
Diameter, mm<br />
Length, m<br />
Sanitary sewer syphon hm Yellowhead Bridge connecting to<br />
downtown sewage collection system<br />
Diameter, mm<br />
Length, m<br />
Gravity sewer to intersection of 15" Ave. and Taylor Drive;<br />
construct new manhole<br />
Diameter, mm<br />
Length, m<br />
Gravity sewer along lSfh ~ ve. from Taylor Drive to Birch St.;<br />
connect to 525 diameter sewer<br />
Diameter, mm<br />
Length, m<br />
Pompstation<br />
<strong>Upgrade</strong>MackusRoadPSforPWWFcapacity<br />
Miscellaneous<br />
Modifications to Blackbum WWTP to operate as storage basin<br />
43.3 Cost Estimate<br />
Pipework<br />
200 syphon, S2OOJm<br />
300 gravity sewer<br />
Blackbum, $160/m<br />
Downtown, S250/m<br />
Pumpstation<br />
Mackus Road PS, LS
Section 4.0 - <strong>Blackburn</strong> <strong>Treatment</strong> Options<br />
Miscellaneous<br />
<strong>Blackburn</strong> WWTP modifications to allow lagoons<br />
to operate as storage basins, LS 100,000<br />
Subtotal 1,165,000<br />
Contingencies (15 percent) 175,000<br />
EngineerindAdministration (20 percent) 235,000<br />
GST (3 percent) 35,000<br />
TOTAL 1,610,000<br />
4.4 OPTION 4 - TRANSFER ALL FLOW < 2*ADWF TO LANSDOWNE<br />
ROAD WWTP AND USE THE EXISTING BLACKBURN WWTP TO<br />
TREAT FLOWS > 2*ADWF<br />
4.4.1 Outline<br />
In this option all flows up to 2*ADW would be transferred &om the<br />
Blackbum sewage collection area for treatment at the Lansdowne Road<br />
WWTP. The existing sewage lagoons would be used only to treat wet weather<br />
flows > 2*ADWF. A schematic representation of this option is presented in<br />
Figure 4.4. An yI reduction program is to be initiated and completed to reduce<br />
the volume of wastewater being treated in the lagoons during wet weather and<br />
snowmelt conditions. The existing Mackus Road pumpstation would be<br />
upgraded and a new pumpstation constructed to handle excess flow<br />
>2*ADWF. It is believed that the Lansdowne Road WWTP has sufficient<br />
capacity to handle the projected future 2*ADWF hydraulic and BODnSS<br />
loadings f7om the <strong>Blackburn</strong> sewage collection area. All wet weather flow ><br />
2*ADWF will be pumped to the existing Blackbum WWTP for treatment.<br />
Key activities or capital works associated with this option are as follows:<br />
Implement III reduction program.<br />
<strong>Upgrade</strong> Mackus Road pumpstation to handle projected increased flows.<br />
Ail dry weather flows < 2*ADWF are to be pumped to Lansdowne Road<br />
WWTP; all wet weather flows > 2*ADWF are to be pumped to <strong>Blackburn</strong><br />
WWTP.<br />
Construct trunk gravity sewer and/or forcemain to transfer all flows<br />
SECTION 3<br />
AUDIT OF EXISTING FACILITIES
SECTION 3.0<br />
AUDIT OF EXISTING FACILITIES<br />
3.1 BLACKBURN WASTEWATER TREATMENT PLANT<br />
The <strong>Blackburn</strong> WWTP is adjacent to Foreman Road and treats wastewater<br />
from the Prince George Airport, Airport Hill, Aitcheson and Blackbum areas.<br />
The plant was constructed in 1976 for a design population of 2,500, and<br />
consists of an inlet works, two aerated lagoons with coarse bubble aeration,<br />
and a chlorination facility. h e plant is presently close to both its design<br />
hydraulic and organic loading capacity. Its hydraulic capacity is often<br />
exceeded during wet weather and winterkpring thaw conditions, which<br />
contribute high levels of III to the wastewater flows. Emuent quality is also<br />
impacted during the spring to summer transition as the lagoons warm up.<br />
Lagoon temperatures in the winter are in the order of 0°C to 5"C, and in the<br />
summer they can exceed 20°C.<br />
At the time of the site visit in September 1999, the lagoon system was<br />
producing an emuent quality of BOD5 < 15 mgiL and TSS < 5 mgL. On<br />
average, the lagoon emuent BODj/TSS concentrations are approximately<br />
20120 mgL, with occasional pmit exceedences during high flows in the<br />
spring. During high flow periods, the plant also regularly exceeds the<br />
maximum allowable daily flow stipulated in the discharge permit.<br />
There are also a number of reported operating problems with the plant. These<br />
include the "freezing" of inlet control valves to the lagoons due to corrosion,<br />
and odour generation during the late spring and early summer. The nearest<br />
houses are approximately 100 m away korn the lagoons. Occasional odour<br />
complaints are received, particularly during the spring breakup when the<br />
lagoon temperature increases, anaerobic biological activity increases and rising<br />
sludge is observed. The operators address the problem by pumping sludge<br />
from the primary lagoon to the secondary lagoon over a 6 week period during<br />
this time.<br />
3.1.2 Preliminary <strong>Treatment</strong><br />
The existing screening room has three influent channels: two 600 mm wide<br />
channels (one equipped with a 75 mm trash rack, one bypass) and a central 450
Section 3.0 -Audit of Existing Facilities<br />
mm wide channel equipped with a cornminutor. The wmminutor is operated<br />
once per day manually, and three times per day automatically. For each of<br />
these cycles, the comminutor is run for approximately 5 minutes.<br />
3.1.3 Secondary <strong>Treatment</strong><br />
The screenedtmacerated wastewater flows by gravity to a series of two unlined<br />
aerated lagoons. The primary lagoon (Lagoon 1) has a volume of<br />
approximately 4,500 m3. The secondary lagoon (Lagoon 2) has a volume of<br />
approximately 14,000 m3. The design mTs of the two lagoons are<br />
approximately 5 days and 15 days, respectively. Both lagoons are equipped<br />
with vertical tube coarse bubble aeration diffusers. The aerators are located in<br />
the centre of Lagoon 1, and in the upstream half of Lagoon 2. The downstream<br />
half of Lagoon 2 serves as a sludge settling zone. Air to the lagoons is<br />
supplied by two 60 hp multistage centrifugal blowers. There is some evidence<br />
of rising sludge and excessive surface foarn/scum in Lagoon 1, and abundant<br />
surface algae growth on the downstream half of Lagoon 2.<br />
3.1.4 Effluent Disposal<br />
The plant is equipped with a chlorine contact tank and chlorination equipment.<br />
However, the City has had an exemption from eMuent chlorination at the plant<br />
since 1983. The outlet of the chlorine contact tank is equipped with a V-notch<br />
weir and Miltronics ultrasonic level sensor, which serve as the principal flow<br />
measuring device. Effluent from the plant flows through a 300 mm diameter<br />
outfall pipe to the Fraser River, where it is discharged just below the river low<br />
water mark.<br />
3.1.5 Sludge <strong>Treatment</strong><br />
The plant is not equipped with sludge removal or handling equipment.<br />
Temporary pumps and piping are used to transfer sludge from -Lagoon 1 to<br />
Lagoon 2 during the spring break-up. Buildup of sludge has not been a<br />
problem during 25 years of operation and consequently removal of sludge from<br />
Lagoon 1 or 2 has not been required.<br />
3.2 LANSDOWNE ROAD WASTEWATER TREATMENT PLANT<br />
3.2.1 Outline<br />
The Lansdowne Road WWTP is the City's main wastewater treatment facility<br />
and treats wastewater from all sewered areas within the City with the exception
Section 3.0 -Audit of exist in^ Facilities<br />
of two industrial subdivisions, Western Acres subdivision and the <strong>Blackburn</strong><br />
area The plant was originally constructed as a high rate activated sludge<br />
process. In 1996, the plant was upgraded to a trickling filter/solids contact<br />
(TFISC) process by the addition of trickling filters and new secondary<br />
clarifiers. The most recent upgrade of the plant was designed for population of<br />
115,000 and an average dry weather flow (ADWF) of 44.5 MLld.<br />
Waste primary and secondary sludge from the plant is stabilized by mesophiIic<br />
anaerobic digestion. The digested sludge is dewatered and stored on the plant<br />
site before being trucked off-site for application to agricultural and forested<br />
land.<br />
At the time of the plant visit in September 1999, the plant was treating about<br />
30 ML/d, which is approximately 67 percent of its design capacity. There are<br />
no reported serious operating or odour problems at the plant.<br />
3.2.2 Preliminary <strong>Treatment</strong><br />
<strong>Wastewater</strong> entering the plant is screened on two 1,500 mm wide Envirex<br />
mechanically raked bar screens. The screens have a bar spacing of 19 mm.<br />
Screenings are removed on a belt conveyor to a pneumatic ejector. Each<br />
screen is followed by a 900 mm parshall flume, and Fisher and Porter<br />
ultrasonic level sensor, which serve as the principal flow measuring devices.<br />
The screened wastewater enters two aerated grit removal chambers (only one<br />
unit is normally in service at a time). The grit and scum is dewatered and<br />
trucked off site for disposal at the Regional sanitary landfill.<br />
3.2.3 Primav <strong>Treatment</strong><br />
The screened degriaed wastewater enters two covered rectangular primary<br />
sedimentation tanks. The tanks are equipped with plastic chain and flight, and<br />
cross collector mechanisms. As well, the tanks are equiped with scum removal<br />
devices. Effluent from the sedimentation tanks is collected through a system<br />
of submerged launders and flows into a wet well.<br />
3.2.4 Secondary <strong>Treatment</strong><br />
Secondary treatment consists of biofilters (trickling filters), a solids contact<br />
tank and two circular secondary clarifiers. Primary eMuent from the wet well<br />
is pumped to a series of headers for distribution over the top of the biofilters by<br />
three (2 duty; 1 standby) 60 hp Flygt pumps located in the main pumpstation.<br />
The biofilter pumps for the pumping of primary effluent to the biofilters are
Section 3.0 -Audit of Existing Facilities<br />
equipped with VFD's, and are controlled to maintain a given water level in the<br />
primary effluent channel. The biofilters are equipped with medium density<br />
Brentwmd crossflow media 6 m deep. Odours emanating from the biofilter<br />
are controlled using a cocurrent ventilation system. Aithough the biofilters are<br />
covered, some algae problems have been experienced. However, there does<br />
not appear to be fly or snail problems typically associated with trickling filters.<br />
Effluent kom the biofilters is pumped to the solids contact tank by three (2<br />
duty; 1 standby) 60 hp Flygt pumps located in the main pumpstation. The<br />
biofilter underflow pumps are equipped with VFD's. The solids contact tank is<br />
equipped with Wyss rubber sheath diffusers manufactured by Parkson.<br />
Aeration air is supplied by two (1 duty; 1 standby) 50 hp Aerzen positive<br />
displacement blowers. Mixed liquor in the solids contact tank appears to have<br />
good sludge settling properties, with SVI's generally between 65 and 75 mL/g.<br />
Mixed liquor from the solids contact tank flow by gravity to two 29 m<br />
diameter secondary clarifiers. The clarifiers are equipped with double sided<br />
inboard emuent launders and "Tow-Bro" rapid sludge removal mechanisms<br />
manufactured by Envirex. Return biological solids (RBS) are pumped from<br />
the secondary clarifiers to the solids contact tank by thee (2 duty; 1 standby)<br />
30 hp Flygt pumps located in the main pumpstation.<br />
3.2.5 Emnent Disposal<br />
The plant is equipped for effluent disinfection and dechlorination using<br />
gaseous chlorine and sulphur dioxide. However, these facilities are not<br />
currently in use as the City has an exemption h m effluent chlorination.<br />
Effluent from the plant discharges to the Fraser River through a 900m diameter<br />
outfall pipe.<br />
3.2.6 Sludge <strong>Treatment</strong><br />
Approximately 2.5 L/s of waste secondary sludge is continuously bled off the<br />
RBS line and returned to the inlet of the primary sedimentation tanks for cothickening<br />
with the primary sludge. The waste primary and secondary sludge<br />
mixture is pumped to two mesophilic anaerobic digesters for stabilization. The<br />
two digesters are operated in series, one as a primary and the other as a<br />
secondary digester. Both digesters are equipped with floating covers. Digester<br />
heating is provided by 2 (1 duty; 1 standby) low pressure boilers. Digester gas<br />
is also used to power a 250 hp cogeneration unit manufactured by Caterpillar.<br />
The primary digester is reseeded every 2 weeks using sludge from the
Section 3.0 -Audit of Existing Facilities<br />
secondary digester. Sodium percarbonate is added to the digesters for<br />
hydrogen sulphide and odour control.<br />
The digested sludge is dewatered on belt filter presses manufactured by<br />
Envirex. Each press has a 2 rn wide gravity section, and a 1 m wide pressure<br />
section. The presses are operated for 7 h/4 4 to 5 &week. Percol757 polymer<br />
and a potato starch based product (Raifix) are used as coagulants. The presses<br />
produce a sludge cake with a dry weight solids content of approximately 22<br />
percent.<br />
3.3 Operations Staff<br />
The <strong>Blackburn</strong> and Lansdowne Road WWTPs are operated by a full time sta!T<br />
of eight persons consisting of one Class IV chief operator, a laboratory<br />
technician, 2 Class I1 operators, and 4 Class I operators. The operating staff<br />
are all based at the Lansdowne Road facility, where most of their duties are<br />
carried out. One operator spends 1 hld, 7 dweek to do a daily inspection at the<br />
<strong>Blackburn</strong> WWTP, and 4 hours once monthly to do the effluent composite<br />
sampling and preventive maintenance. Other City tradespeople (millwright,<br />
electrician, instrument technician) are called to the plants on an "as required"<br />
basis.<br />
3.4 Conclusion<br />
The existing Lansdowne Road WWTP was designed for an ADWF of 44.5<br />
Mud and a PWWF of 115 Mud. The plant is currently treating<br />
approximately 30 MU& or 67 percent of its design flow and load, and does not<br />
appear to have any unit processes in either the liquid or sludge treatment<br />
streams that are close to capacity and may serve as a "bottleneck" if flows to<br />
the plant were increased by a modest amount. The current dry weather flows<br />
and loads h m the Blackbum catchment represent less than 2 percent of the<br />
design capacity of the Lansdowne Road WWTP. The current wet weather<br />
flows (i.e. prior to implementation of the VI mitigation measures) represent<br />
less than 5 percent of the hydraulic capacity of the Lansdowne Road WWTP.<br />
Even with the expected increase in flows and loads from Blackbum sewage<br />
collection area as a result of increasing the serviced population to 5,000, these<br />
flows and loads represent less than 4 percent of the design capacity of the<br />
Lansdowne Road WWTP.
SECTION 2<br />
I/I MITIGATION MEASURES
SECTION 2.0<br />
III MITIGATION MEASURES<br />
2.1 INTRODUCTION<br />
Snowmelt and rainfall that enters a sanitary sewer during wet weather periods can be<br />
categorized as either inflow or infiltration. Inflows are due to direct connections of<br />
rainfall and/or snowmelt and contribute to rapid flow increases, whereas infiltration is<br />
due to indirect sources and produces delayed flows and extended flow increases.<br />
Therefore, inflows are critical for short high intensity as well as for long duration<br />
storms; infiltration would be critical for Iong duration events. Since prolonged wet<br />
weather, due to winter thaws and spring raidthaw conditions, is quite normal in the<br />
BIackbum area, both inflow and infiltration (III) contribute significantly to the<br />
overloading of sanitary sewers.<br />
Excessive H places significant peak flow demands on the sanitary sewer system.<br />
Retrofit measures such as upgrading capacity of pipes, pumpstations, and treatment<br />
facilities can substantially increase the cost of providing sewer service. On the other<br />
hand, realizing the significance of yI and impIementing a program of L'l reduction can<br />
extend the life of facilities by deferring the need to upgrade hydraulic capacity.<br />
Controlling excessive amounts of VI is the single largest demand-side management<br />
issue for any wastewater collection system. Therefore, a planned yI investigation and<br />
analysis methodology can be adopted to: detect and identify these It1 sources on a site<br />
specific basis; quantify their comparative impacts; find appropriate mitigative<br />
measures on a prioritized basis; and implement policies that promotes the reduction of<br />
excessive UI.<br />
A Mica1 I/I mitigation work plan methodology recognizes that:<br />
Within the sewer network, major VI sources can be 'leaky' manholes, poor pipe<br />
joints, poor senice connections, and failed pipes.<br />
High ground water table during wet weather periods can create high hydraulic<br />
heads, which result in continuous UI through the defective components of the<br />
sewer network.<br />
A significant portion of UI is often generated within private property.<br />
Since a major source of the UI can be generated on individual lots, the potential<br />
costbenefits of implementing I/l reduction measures on private property should be<br />
part of the solution.
Section 2.0 - III Mitigation Measures<br />
The I/I control program should incorporate ongoing performance monitoring by<br />
collecting additional performance data to monitor the cost effectiveness of the<br />
various rehabilitation techniques.<br />
It is important to control both the "on-lot" UI and "on-street" I/I by developing a<br />
public information/participation component into the IT management strategy. Control<br />
of "on lot" V1 has significant merit as it is a 'source control' at the top end which<br />
eliminates entry into the sewer network. However, it can be hught with the often<br />
challenging need to get the homeowner's buy-in. This would need a review of the<br />
service connection and lot grading practiceshy-laws applicable to existing lots as well<br />
as future developments.<br />
The City commissioned Stantec Consulting Ltd. to complete a study on Vl in the<br />
<strong>Blackburn</strong> sewage collection area Ad present conclusions and recommendations. The<br />
final report was submitted June, 1999. Attached as Appendix A are the conclusions of<br />
this report. In short, the Stantec Consulting report recommended that the most cost<br />
effective approach to the VI problem was to implement a rehabilitation program for<br />
manholes and the collection pipework.<br />
Based on the Stantec Consulting report recommendations, the City plans to implement<br />
during the operating year of 1999 a manhole rehabilitation program and attempt to<br />
reduce by the end of 2000, PWWF by nearly 50 percent. Over the following 5 to 10<br />
years, the VI reduction program would be ongoing.<br />
2.2 IA REDUCTION PLAN<br />
2.2.1 Inflow Reduction<br />
The manhole rehabilitation work, set out by Stantec Consulting Ltd., has been<br />
predicted to reduce the volume of inflow by 2,170 m3/d. Tnis brings the peak wet<br />
weather flow (PWWF) down from 4,500 m3/d to 2,330 m3/d. However, this still<br />
exceeds the limits of the discharge permit. Tberefore, Wher reduction of Ill is<br />
required to meet design and permit requirements.<br />
2.2.2 Infiltration Reduction<br />
Population<br />
Currently, the population for the Blackbum sewerage area is estimated to be 1,800. A<br />
population growth rate of approximately 4.2 percent is assumed for the area and based<br />
on this growth rate the population in 25 years will be 5,000. See Table 2.1.
Section 2.0 - UI Mitigation Measures<br />
Sanitary Design Flow<br />
Using a sanitary design flow value of 350 L/cap/d and contributing population of<br />
1,800, the current average dry weather flow (ADWF) can be calculated as 630 m3/d.<br />
The design allowable PWWF can then be determined at 2 x ADWF as 1,260 m3/d.<br />
Using this calculation, the discharge permit limit of 1,375 m3/d at the Blackbum<br />
WWTP would be exceeded in the year 2002 assuming apopulation of 2,035.<br />
Projected PWWF<br />
Projected PWWFs are calculated on the basis of the PWWF volume recorded during<br />
the March 25,1999 period. As discussed above, the manhole rehabilitation program is<br />
predicted to reduce the inflow portion of M, decreasing the PWWF kom 4,500 m3/d to<br />
2,330 m3/d. In order to reduce this flow to the PWWF permit allowable requirements,<br />
infiltration will have to be reduced. The infiltration portion of UI is calculated as:<br />
Infiltration (1999), m3/d = P W -Inflow - Design PWWF (1999)<br />
- 4,500-2,170- 1,260<br />
- 1,070<br />
The reduction of infiltration could be accomplished by rehabilitating pipes, pipe joints,<br />
manholes, and service connections over a 5 or 10 year implementation period.<br />
5 Year Rehabilitation Plan<br />
The 5-year plan investigates the reduction of 1,070 m3/d over a 5 year period. This<br />
equates to a reduction of approximately 215 m31dly assuming a PWWF (2004) of<br />
1,545 m3/d. Table 2.1 lists PWWF reductions over a 5 year period.<br />
10 Yar Rehabilitation Plan<br />
Much like the 5 year plan, the 10 year plan investigates the reduction of 1,070 m3/d<br />
over a 10 year period. This equates to a reduction of approximately 105 m3/ay,<br />
assuming a PWWF (2009) of 1,895m3/d. Table 2.1 lists PWWF reductions over a 10<br />
year period.<br />
Figure 2.1 compares the projected PWWF to the design P IW over a 25 year period.<br />
2.3 REHABILITATION COST ESTIMATES<br />
As described previously, the volume of inflow is estimated as 2,170 m3/d and the<br />
volume of infiltration as 1,070 m3/d. The ratio of inflow to total VI is 67 percent; and<br />
for infiliration 33 percent.
Section 2.0 - UI Mitigation Measures<br />
Infiltration can enter a sewer system through deficiencies or cracks in 3 categories of<br />
the sewer line: connections, in-street pipes including joints, and manholes. Infiltration<br />
that can be expected to result from each of the 3 categories is calculated on a mmdiameter-m<br />
basis. Other assumptions involved in the proportioning of infiltration<br />
amongst pipes, manholes, and connections is the lower construction standards of<br />
connection installment (45 percent), and the 7 mt10 m split of municipaVprivate<br />
connection length.<br />
Table 2.2a calculates that of the 33 percent of III that is infiltration, approximately 21<br />
percent is from pipes, 3 percent from manholes, 4 percent from municipal connections,<br />
and 5 percent from private connections.<br />
Table 2.2b and Table 2.2~ calculate the percent infiltration reduction required from<br />
pipes including joints, manholes, and connections in order to reach the required yearly<br />
reduction as previously described in Table 2.1. The amount of physicaf rehabilitation<br />
is based on the assumption that grouting a section of pipe will only reduce its<br />
contribution to infiltration by a maximum of 75 percent. Therefore, the percent of<br />
rehabilitation must be higher in order to achieve the required percent of infiltration<br />
reduction. For example, during the first year (2000) of the 5 year plan, about 6 percent<br />
of the infiltration in pipes must be reduced. This means that approximately 8 percent<br />
ofpipes must be grouted to achieve the required reductions in infiltration.<br />
Table 2.3a and Table 2.3b estimates the cost of rehabilitation based on the grouting of<br />
each sewer element. The cost of grouting is assumed as follows:<br />
Pipes, $/m<br />
Manholes, $/unit<br />
Connections, $/m<br />
The total cost for the 5 year and 10 year rehabilitation plans are $1,580,000 and<br />
$1,120,000 respectively. The Net Present Value (NPV) is calculatd in Table 2.4.<br />
Based on an annual discount rate of 6 percent, the NPV for the 5 and 10 year plans are<br />
$1,319,000 and 5815,000 respectively.<br />
The 10 year plan requires less work to be done as it is based on the percentage of flow<br />
reduction each year to the previous year. Therefore, the overall capital cost is<br />
$460,000 less than the 5 year plan. However, it should be noted, that by committing<br />
to a 10 year plan, the City of Prince George is not meeting the 2 x ADWF criteria for<br />
the Blackbum sewerage area for an additional 5 years. This makes the 5 year plan a<br />
flow based benefit plan, and the 10 year plan a cost based benefit plan.
APPENDIX E<br />
FLOW CALCULATIONS FOR SEWER UPGRADES
.<br />
Date: 23 December 1999<br />
File: 1174-01-01<br />
Reid Crowther & Partners Ltd.<br />
Consulting Engineers<br />
300, 41 70 Still Creek Drive<br />
Burnaby, British Columbia<br />
V5C 6C6<br />
Attention:<br />
Mr. Andv North. P.Ena.<br />
Dear Andy,<br />
AS recently requested by Les Nemeth. P.Eng.. please find attached our flow calculatio'n - ,<br />
,<br />
...<br />
spreadsheet showing the capacity of the existing sanitary sewer mains from the ~e~ional , ' -<br />
. .<br />
Correctional Centre to tlie discharge into the 600mm diameter City trunk sanitary . .<br />
. .<br />
. . . .<br />
sewermain on Taylor Drive. -<br />
. .<br />
. ........<br />
. .<br />
. . .. -<br />
,-<br />
..<br />
The estimated future peak PU~P~IOW<br />
rate.from the Mackus Road sewage lift station is -<br />
.....<br />
..- .<br />
50 Lls (0.05 mals). The section :of existing 200mm diameter sewer main from the I' ~ .,<br />
. ~<br />
discharge point of the 200mm diameter syphon, at MH KL23a to the intersection'of the ......<br />
525 mm diameter main at Birch Street, will need to be upgradbd,to a 300mm diameter . . ,<br />
pipe at a-minimum. grade of 0.3% to handle the futire pumped peak flows'of ':