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SEWPCC Upgrading/Expansion Preliminary Design Report
SECTION 4 - POPULATION AND FLOW PROJECTIVES
Table of Contents
4.0 POPULATION AND FLOW PROJECTIONS.................................................................4.1 4.1 POPULATION FORECAST ...........................................................................................4.1
4.1.1 Source Data .....................................................................................................4.1 4.1.2 Method of Projection Population ......................................................................4.1 4.1.3 Factors Affecting Population Projection ...........................................................4.2 4.1.4 Population Projection Envelopes .....................................................................4.4 4.1.5 Population Forecast for SEWPCC Service Area..............................................4.7
4.1.5.1 Overview of SEWPCC Service Area.................................................4.7 4.1.5.2 Population Distribution ......................................................................4.8 4.1.5.3 SEWPCC Population Projection .....................................................4.13
4.2 FLOW FORECASTS....................................................................................................4.15 4.2.1 Dry-Weather Flow (DWF) Projection..............................................................4.15
4.2.1.1 Overall Winnipeg Water Use Trends...............................................4.15 4.2.1.2 SEWPCC Historic DWF ..................................................................4.17 4.2.1.3 Residential Water Use Projections .................................................4.19 4.2.1.4 Projecting Per Capita SEWPCC Wastewater Generation...............4.21 4.2.1.5 SEWPCC DWF Projection ..............................................................4.25 4.2.1.6 DWF Diversions ..............................................................................4.25 4.2.1.7 Hourly DWF Peaking ......................................................................4.28
4.2.2 Wet-Weather Flow (WWF) Projections ..........................................................4.29 4.2.2.1 Introduction .....................................................................................4.29 4.2.2.2 Policy Decision................................................................................4.30 4.2.2.3 Frequency Analysis.........................................................................4.30 4.2.2.4 Flow Frequency Distribution in 2031 Based on Historic
Data Analysis ..................................................................................4.32 4.2.2.5 Accounting for Potential Sanitary Sewer Overflows (SSO).............4.33 4.2.2.6 Estimated Hourly Wet-Weather Peak .............................................4.38 4.2.2.7 Sensitivity Analysis of Limiting I/I in New Areas..............................4.38 4.2.2.8 WWF Diversions .............................................................................4.39
4.2.3 Maximum and Minimum Flows.......................................................................4.39
i
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT
4.0 Population and Flow Projections
4.1 POPULATION FORECAST
Wastewater flow projections are the basic parameters for determining SEWPCC expansion requirements. Sizing of system components, such as treatment facilities, requires realistic wastewater-flow projections. Dry- and wet-weather flow projections are required for this purpose.
Population forecasting is the first step in developing flow projections. The population data referenced in this report is based on the population data available at the time the report was prepared. The details of steps used in developing population forecasts are described in Section 2. Section 3 and Section 4 describe dry- and wet-weather flow projections, respectively.
Based on the current design considerations, the year 2031 is the design year for the proposed SEWPCC treatment plant expansions. The longer period up to 2050 is also considered for the purpose of overall system evaluations beyond the year 2031.
4.1.1 Source Data
Table 4.1 indicates the sources of existing data used for the overall City of Winnipeg population projection.
Table 4.1 – Existing Database of Winnipeg Population Between 1921 and 2026
Data Date Source and Method
Historic 1921-1986 COW Environmental Planning Department
Historic 1987-2002 Conference Board of Canada (derived by taking 92.3% of Census Metropolitan Area), September 2004
COW Projection 2003-2026 Extrapolated from the Conference Board of Canada
Note: Census Metropolitan Area (CMA) includes COW and municipalities of Richot, Tache, Springfield, East St. Paul, West St. Paul, Rosser, St. Francois Xavier, Headingley, St. Clements and Brokenhead First Nation.
4.1.2 Method of Projection Population
The overall City of Winnipeg base population projection for the years 2003-2026 was developed by the City of Winnipeg based on estimates of age distribution and net migrations during this
4.1
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
period. The present study considered the same demographics and net migration factors to extrapolate Winnipeg’s population to 2031 and beyond to 2050 as demonstrated in Figure 4.1.
Figure 4.1 - TetrES Extrapolation of City of Winnipeg Population Forecast (2027-2050)
200,000
300,000
400,000
500,000
600,000
700,000
800,000
900,000
1,000,000
1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050
Year
Popu
latio
n
Extrapolated by COW (2003-2026)
Extrapolated by TCI (2027-2050)
Historic Data (1921-2002)
4.1.3 Factors Affecting Population Projection
Net migration is a significant factor affecting Winnipeg’s population growth as shown in Figure 4.2. Net migration is the difference between the number of people moving to Winnipeg each year and the number of people leaving. If net migration is positive, then the number of people migrating to Winnipeg is greater than the number migrating from Winnipeg.
4.2
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
-8,000
-6,000
-4,000
-2,000
0
2,000
4,000
6,000
8,000
1980 1990 2000 2010 2020 2030 2040 2050 2060
Year
Net
Mig
ratio
n
Extrapolated by COW from
Conference Board of Canada
(2003-2026)Historic Data(1987-2002)
Figure 4.2 - Existing Data for Net Migration (Statistics Canada: The Conference Board of Canada; derived by taking 92.3% of CMA)
The Conference Board projection shows overall net migration increasing from approximately 2,200 per year (in 2006) to 4,400 per year by 2026. This is much higher than the historic average and therefore assumes stronger economic growth into the future.
The study team estimated the net migration trend to increase from 4,420 per year in 2027 to 7,700 per year in 2050. This projection was estimated by extrapolating the Conference Board of Canada net migration data between 2006 and 2026 (Figure 4.2). Another population projection scenario considers a stable net migration in which the growth rate remains constant at 4,420 per year from 2027 to 2050 as illustrated in Figure 4.3.
4.3
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
-8,000
-6,000
-4,000
-2,000
0
2,000
4,000
6,000
8,000
1980 1990 2000 2010 2020 2030 2040 2050 2060
Year
Net
Mig
ratio
n
Historic Data(1987-2002)
Extrapolated by TCI
(2027-2050)
Proposed Design Period (2031) 2050
Extrapolated by COW from
Conference Board of Canada
(2003-2026)
Stable Net Migration
Figure 4.3 - Net Migration Projections4.1.4 Population Projection Envelopes
Population projection envelopes are used to identify the reasonable range for overall population projection. In this study, the population projection envelopes are developed based on the following scenarios (Figure 4.4):
1. Low net migration rate (50% of mid-net migration)
2. Mid-net migration rate (Conference Board projections extended to 2050)
3. High net migration rate (150% of mid-net migration)
4.4
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
-8,000
-6,000
-4,000
-2,000
0
2,000
4,000
6,000
8,000
10,000
12,000
1980 1990 2000 2010 2020 2030 2040 2050 2060
Year
Net
Mig
ratio
n
Proposed Design Period (2031)
High Net Migration Rate
Low Net Migration Rate
Mid Net Migration Rate
2006 2050
Figure 4.4 - Net Migration Range
Figure 4.5 shows the results of overall population forecasts for the City of Winnipeg when different net migration rates are applied.
Based on the assumptions made regarding net migration rates, Winnipeg’s population is expected to increase consistently over time. The average annual rate of growth is about 0.7% per year. The population estimate for 2031 ranges between 754,000 and 807,300 (see Table 4.2), while corresponding percent increase ranges between 16% and 24%, respectively. The stable migration scenario shows that if net migration was to remain constant, the population growth rate would slow. In 2050, the stable migration scenario is just below the lower limit of the projection envelope.
4.5
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
4.6
200,000
300,000
400,000
500,000
600,000
700,000
800,000
900,000
1,000,000
1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050
Year
Popu
latio
n
Mid Net Migration
Low Net Migration Rate
High Net Migration RateStable Net Migration
Historic Data (1921-2002)
Proposed Design Period (2031)
Extrapolated by COW (2003-2026)
Extrapolated by TCI (2027-2050)
2050
This study utilizes the mid-range projection that estimates Winnipeg’s population at 780,700 in 2031.
Figure 4.5 - Population Forecast for the City of Winnipeg
Table 4.2 – Overall Population Forecast (Entire City)
Population
Category 2005* (estimate) 2031
% Growth (2005-2031)
2050 % Growth
(2005-2050)
Stable Net Migration Rate 652,200 769,500 18% 825,600 27%
Low Net Migration Rate 652,200 754,000 16% 832,900 28%
TCI Mid-Range Net Migration Rate 652,200 780,700 20% 876,300 34%
High Net Migration Rate 652,200 807,300 24% 919,700 41%
Note: *projected from 2001 to 2005
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
4.1.5 Population Forecast for SEWPCC Service Area
4.1.5.1 Overview of SEWPCC Service Area
The SEWPCC service area is the second largest service area in Winnipeg; however, it has the greatest potential for growth. There are large areas within the SEWPCC service area for population growth within Winnipeg (Figure 4.6). A coarse estimate of the current developed area in the SEWPCC is about 6,500 ha (excluding parks). The ultimate developed area is about 15,000 ha. Assuming about 5% of the area will remain undeveloped and the population density remains the same, the ultimate population in the service area would be about 400,000.
4.7
Figure 4.6 - Map of Overall WPCC Service Areas
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
4.1.5.2 Population Distribution
To determine the SEWPCC population growth, an understanding of historic and projected distribution of population growth between the three WPCC service areas is required. A number of sources were reviewed to determine the historic distribution of population growth within the City.
Figure 4.7 illustrates the historic population from 1971 to 2001, based on service area (Memorandum from Chris Tait, July 20, 1999; and 2001 census data). The SEWPCC service area has received 63% of the City’s new population growth during this period.
50,000
100,000
150,000
200,000
250,000
300,000
350,000
400,000
450,000
500,000
1960 1970 1980 1990 2000 2010 2020 2030 2040 2050 2060
Year
Popu
latio
n
NEWPCC (21% of Growth)
SEWPCC (63% of Growth)
WEWPCC (16% of Growth)
Figure 4.7 - Historic Population Estimate Based on Service Area (City of Winnipeg 1999)
The single-family dwelling permits by neighbourhood from 2003 and 2004 were reviewed to determine recent trends in population distribution (see Figure 4.8).
4.8
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
Figure 4.8 - Single-Family Dwelling Permits by Neighbourhood (Jan/03 to Jun/04) (City of Winnipeg Residential Land Supply Study Oct/04)
Between 2003 and 2004, the SEWPCC service area had the largest portion of single-family permits (69%), while the NEWPCC and WEWPCC service areas had 27% and 4% permits, respectively. Table 4.3 summarizes the 2003-2004 percent distribution based on each service area.
4.9
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
Table 4.3 – Summary of 2003-2004 Single-Family Permits Based on Service Area
Location SEWPCC NEWPCC WEWPCC
Number of Dwelling Permits 3,320 1,300 175
% Distribution 69% 27% 4%
The City of Winnipeg Planning Department has projected the most likely areas of development across the City for the years 2005 to 2021. Figure 4.9 illustrates the long-term City of Winnipeg planning distribution for residential development.
Figure 4.9 - Forecasted Residential Development (2005-2021) (City of Winnipeg, December 2005)
4.10
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
4.11
In long-term residential development (2005-2021) plan, the distribution of population towards the SEWPCC area will increase over time from 2005 to 2021. Beyond 2021, the study team has projected that about 70% of new population growth will be in the SEWPCC service area. After 2021, the SEWPCC service area will still have considerable land available for development (see Table 4.6).
Methods used to allocate the population distribution to the SEWPCC service area are summarized in Table 4.4. Table 4.5 summarizes the population distributions among service areas for the historic and future planning periods.
Table 4.4 – Allocation of Population Distribution to the SEWPCC Service Area
Distribution Period Method of Allocation
1971 to 1996 Historic trend from COW data
1996 to 2001 Census 2001 data
2001 to 2005 2003 to 2004 housing permits
2005 to 2011 2005 to 2011 estimated projection from COW planning
2012 to 2021 2012 to 2021 estimated projection from COW planning
2022 to 2050 2022 to 2050 estimated projection from TCI
Table 4.5 – Summary of Population Distribution by Service Area
Estimated Projection from Planning
Location Historic1
(1971-1996)
Dwelling Permits2
(2003-2004) 2005-20113 2012-20213
2022-2050
(TCI this study)4
SEWPCC 63% 69% 42% 57% 70%
NEWPCC 21% 27% 44% 19% 10%
WEWPCC 16% 4% 14% 24% 20%
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
4.12
1. Revised estimated based on current Information, based on the COW Water and Wastewater Dept., memo from Chris Tait, July 20, 1999.
2. Planning, Property, and Development Planning and Land Use Division, COW Residential Land Supply Study, October 2004.
3. COW Forecasted Residential Land Development Study (Draft), December 2005.
4. TetrES Consultants Inc. (this study).
High and low estimates of new population growth distributed to the SEWPCC service area were identified in order to provide an indication of the range of population that the SEWPCC may need to serve. A variance of +/-5% was assigned for the development period from 2005 to 2011, while a wider variance of +/-10% was assigned for the period from 2012 to 2050. Table 4.6 summarizes the low, mid and high population distribution percentages used in this study.
Table 4.6 – Potential Population Distribution Range for the SEWPCC Service Area
Development Period
Low Population Distribution to
SEWPCC
Mid Population Distribution to
SEWPCC
High Population Distribution to
SEWPCC
2005-2011 37% 42% 47%
2012-2021 47% 57% 67%
2022-2050 60% 70% 80%
The five combinations of migration rates and distribution percentages used in this study to develop SEWPCC population projections are as follows:
1) Low net migration rate and low population distribution.
2) Mid net migration rate and low population distribution.
3) Mid net migration rate and mid population distribution.
4) Mid net migration rate and high population distribution.
5) High net migration rate and high population distribution.
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
Note that Scenarios 2, 3 and 4 use the mid net migration rate which was chosen for future design purposes. Scenarios 1 and 5 are considered in order to identify potential upper and lower bounds on the estimated population in the SEWPCC service area.
4.1.5.3 SEWPCC Population Projection
Figure 4.10 illustrates a comparison of current population projections for the SEWPCC service area and previous COW projections from 2003. The current City population projection is slightly higher, while the SEWPCC population projection is similar.
50,000
150,000
250,000
350,000
450,000
550,000
650,000
750,000
850,000
950,000
1960 1970 1980 1990 2000 2010 2020 2030 2040 2050 2060
Year
Popu
latio
n
High population distribution to SEWPCC
Mid population distribution to SEWPCC
Low population distribution to SEWPCC
Historic Data
Old COW Projection (2003)
Old Total COW Population Projection (2003)
New COW Total Population Projection (2004)
TCI
Figure 4.10 – Comparison of Population Forecasts for SEWPCC Service Area with Previous Projection
Figure 4.11 shows the population forecasts for the SEWPCC service area based on the five combinations of net migration and population distribution listed above.
4.13
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
4.14
Figure 4.11 - Population Forecasts for SEWPCC Service Area
50,000
100,000
150,000
200,000
250,000
300,000
350,000
400,000
450,000
500,000
1960 1970 1980 1990 2000 2010 2020 2030 2040 2050 2060
Year
Popu
latio
n
Mid net migration rate and low population distribution
Mid net migration rate and low population distribution
Mid net migration rate and mid population distribution
Proposed Design Period (2031)
Historic Data
High net migration rate and high population
distribution
Low net migration rate and low population distribution
In 2031, the population growth for SEWPCC service area ranges between 28% and 56% (see Table 4.7). The scenario with low migration rate and low population growth results in the lowest population increase of 229,800 by 2031, while the high migration rate and high population growth scenario produces the highest population increases at 281,000.
The scenarios using a mid migration rate combined with low and high population growth result in the SEWPCC service area population projects of approximately 241,900 and 264,600 respectively by 2031.
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
4.15
Table 4.7 – Summary of Population Forecast for SEWPCC Service Area
Population Distribution for SEWPCC Option
2005* 2031 % Growth
(2005-2031)
2050 % Growth
(2005-2050)
Low migration rate with low population distribution to SEWPCC
179,400 229,800 28% 278,100 55%
Low population growth 179,400 241,900 35% 301,900 68%
Mid-net migration and population distribution to SEWPCC
179,400 253,300 41% 323,300 80%
High population growth 179,400 264,600 47% 344,700 92%
High migration rate with high population distribution to SEWPCC
179,400 281,000 56% 376,700 109%
*projected from 2001 to 2005
In the July 6, 2006 Workshop, the City expressed concerns that if the population growth was not as high as projected by the middle projection, the SEWPCC would be “overbuilt.” Selecting a lower projection provides more flexibility and allow for further expansion at a later date.
In response to the City of Winnipeg direction provided at the July 6, 2006 workshop, the lowest migration rate with low population distribution option has been selected for developing dry- and wet-weather flow projections. The design population is selected at 229,800 in the year 2031.
4.2 FLOW FORECASTS
4.2.1 Dry-Weather Flow (DWF) Projection
4.2.1.1 Overall Winnipeg Water Use Trends
The historic citywide pumping records were reviewed to estimate per capita water use. Figure 4.12 illustrates citywide average daily water use (million litres per day – ML/d) in January from 1955 to 2004.
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
The daily per capita water use (litres per capital per day – lcd) was calculated for each year and is shown in Figure 4.13. Dry-weather wastewater generation within the City of Winnipeg is driven by water use, therefore, wastewater generation in winter should show the same general trend as water use.
0
50
100
150
200
250
300
1950 1960 1970 1980 1990 2000 2010
Year
Wat
er U
se (M
LD)
Figure 4.12 - Winnipeg Average Daily Water Use in January (1955-2004)
050
100150
200250300
350400
450500
1950 1960 1970 1980 1990 2000 2010
Year
Per C
apita
Wat
er U
Se (l
cd)
4.16
Figure 4.13 - Winnipeg Water Use per Capita in January (1955-2004)
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
The historic Winnipeg water use (Figure 4.12) has significantly increased over the decades from a low of 129 ML/d in 1955 to a peak of 275 ML/d in 1990, and had gradually dropped to about 211 ML/d by the end of 2004. Per capita water demand (Figure 4.13) has also shown a significant downward trend in the past 15 years despite increasing population.
4.2.1.2 SEWPCC Historic DWF
Figure 4.14 illustrates SEWPCC DWF from 1983 to 2005. This figure shows that there has been no growth in DWF over the past 15 years. However, the population within this service area has grown over the past 15 years, and therefore, the per capita wastewater generation has decreased substantially, as shown in Figure 4.15.
0
10
20
30
40
50
60
1980 1985 1990 1995 2000 2005 2010
Year
Pum
ping
Vol
ume
(MLD
)
Figure 4.14 - Average Daily SEWPCC Pumping Records in December and January (1983-2005)
4.17
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
Figure 4.15 - SEWPCC Average Daily Wastewater Generation per
Capita in January and December (1983-2005)
200
220
240
260
280
300
320
340
360
1980 1985 1990 1995 2000 2005 2010
Year
Was
tew
ater
Gen
erat
ion
(lcd)
The citywide trend for per capita water use and the SEWPCC per capita wastewater generation rates are very similar, both showing significant decreases over the past 15 years.
Wastewater generation by residential, commercial, and industrial sectors was estimated using the City of Winnipeg Water Conservation Database for the SEWPCC service area (see Table 4.8). To obtain the per capita demand for each water use sector requires verification and summation of individual customer account readings. The method requires obtaining actual utility-read or self-read meter readings and excluding estimates developed by the utility for billing purposes. Since many occupants are not read every quarter, it may take a couple of years before an accurate sector estimate can be obtained. Total wastewater flows are measured daily at each WPCC; therefore, this analysis performed (last column in Table 4.8) is more up to date. This analysis shown in the table was performed in 2006 based on the information provided by the City in early 2006. The water consumption sector estimates and the infiltration estimate (wastewater flow minus water consumption) can only be estimated to the year 2003 at this time.
4.18
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
Table 4.8 – Water Use Record for SEWPCC Service Area (Winnipeg Water Account COW Water Conservation Database, 1993-2003)
Year Residential (lcd)
Commercial (lcd)
Industrial and other
(lcd)
Total Water Consumption
(lcd)
Infiltration (lcd)
Total SEWPCC
Wastewater Base Flow
(lcd)
1993 218 43 16 277 55 3321994 217 43 14 274 80 3551995 218 48 17 283 56 3391996 217 41 17 275 56 3321997 213 41 19 273 57 3311998 211 42 17 270 46 3181999 211 50 15 276 39 3172000 209 47 15 271 44 3172001 208 46 16 270 52 3252002 209 45 16 270 25 2972003 206 43 14 263 25 2902004 2992005 302
*Mid-winter per capita wastewater generation for the SEWPCC used an estimate of the population that does no
he residential water consumption has decreased over time from a high of 218 lcd in 1993 to as
n rate is
Residential water usage is a driving factor for SEWPCC wastewater generation. In order to del
play a r
ts
t include Windsor Park
Tlow as 208 lcd in 2003. The commercial and industrial water consumptions vary from year to year with slight declining trend since 1999. The winter infiltration rate was estimated by subtracting per capita water use from SEWPCC per capita pumping rates. This infiltratiovariable from year to year.
4.2.1.3 Residential Water Use Projections
project residential wastewater use in the future, this study used the residential water use modeveloped by TetrES and the City of Winnipeg Water and Waste Department in 1998. Technology change that impacts water-using appliances such as toilets, is expected to major role in reducing water consumption across the City and in the SEWPCC service area. Foexample, changing technology could reduce per capita toilet water use from 73 lcd in 1992 to 30 lcd in 2046 (see Figure 4.16). Figure 4.17 illustrates the projected transition of toilets used in residences across the SEWPCC area. The effect of new construction using more efficient toileand a renovation rate of 6% per year has been assumed to develop this projection.
4.19
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
Toilets (73 )Washers (41 )
Dishwasher (7 )Cooking/Drinking (2 )
Cleaning (2 )
Toilet Leaks (14 )
Showers (46 )
Faucets (20 )
Bath (23 )
1992 (228 LCD)
Toilets (59 )Washers (41 )
Dishwasher (7 )Cooking/Drinking (2 )
Cleaning (2 )
ToiletLeaks (14 )
Showers (49 )
Faucets (20 )
Bath (23 )
2004 (217 LCD)
Toilet Leaks (14 )
Toilets (41 )
Washers (37 )
Dishwasher (7 )Cooking/Drinking (2 )
Cleaning (2 )
Showers (48 )
Faucets (20 )
Bath (23 )
2019 (196 LCD)
ToiletLeaks (14 )
Toilets (30 )
Washers (33 )
Dishwasher (7 )Cooking/Drinking (2 )
Cleaning (2 )
Faucets (20 )
Bath (23 )
2046 (174 LCD)
Showers (42 )
Residential Indoor Water Use
Figure 4.16 Effects of Technology Change (TetrES 1998)
4.20
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
Toilets account for a large portion of indoor water consumption, therefore, replacing the existing toilets using 22 litres/flush or 13 litres/flush with those using 6 litres/flush is expected to reduce future per-capita wastewater generation in the SEWPCC area.
4.2.1.4 Projecting Per Capita SEWPCC Wastewater Generation
Commercial water usage was estimated approximately at 45 lcd, which is lower than the citywide water usage of 75 lcd in 1998. The trend of 45 lcd is expected to remain constant in the future. The industrial water usage was estimated at only 15 lcd, which is much lower than the citywide average industrial water usage of 50 lcd in 1998. This trend is also expected to remain constant in the future. In this projection, it is assumed that mid-winter infiltration will remain at 48 lcd into the future.
he effects of technology change are taken into consideration for the residential water projection. The key components of residential water usage are toilets, showers, bath, faucets, washers, dishwas jected per capita
r use.
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
1992 1997 2002 2007 2012 2017 2022 2027 2032 2037 2042 2047
Year
Perc
ent o
f Typ
e
22 Litres/Flush13 Litres/Flush6 Litres/Flush
Figure 4.17 - Transition in Toilets Used
T
her, cooking/drinking and cleaning. Figure 4.18 shows the prousage for various components of residential wate
4.21
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
4.22
Overall residential per capita water use trend (0% renovation rate) for the SEWPCC service area is expected to be relatively constant with a slightly decreasing trend by the end of 2050 (Figure 4.18) from 222 lcd in 1993 to 208 lcd in 2050. After 2050, it is assumed that there will be no growth in per capita demand. Figure 4.19 illustrates a comparison of different renovation rates for residential per capita water demand projection.
Figure 4.18 - Long-Term Residential per Capita Water Demanrate)
d (0% renovation
100
120
140
160
180
200
220
240
1980 1990 2000 2010 2020 2030 2040 2050 2060
Year
Per C
apita
Dem
and
(lcd)
Data0% renovation rate
213 lcd
2031
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
is evident that home renovation plays a key role in residential water usage in which higher rate
of h emand r different renovation rates is illustrated in Table 4.9.
4.23
Itome renovation decreases residential per capita water demand. The estimate water d
fo
Table 4.9 – Effect of Home Renovation on Residential per Capita Demand
Option Estimated SEWPCC Projections lcd in 2031
0% renovation rate 213
2% renovation rate 190
4% renovation rate 176
6% renovation rate 169
100
120
140
160
180
200
220
240
1980 1990 2000 2010 2020 2030 2040 2050 2060
Year
Per C
apita
Dem
and
(lcd)
Data0% renovation rate2% renovation rate4% renovation rate6% renovation rate
213 lcd
176 lcd
169 lcd
190 lcd
2031
Figure 4.19 - Effect of Renovation Activities on Residential per Capita Water Demand Projection
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
In 2031, the estimate of residential per capital demand based on different renovation rates nges between 169 lcd and 213 lcd, respectively. The scenario with 0% renovation rate results
in the highest per capital water demand of 213 lcd, while the 6%/year renovation rate scenario roduces the lowest per capital water demand of 169 lcd. While 6%/year renovation rate
provides the “best fit” to the short term data presented (see Figure 4.20), the participants in the uly 6, 2006 Workshop considered it prudent to use a lower renovation rate of 2%/year. In
the City of Winnipeg direction provided at the July 6, 2006 workshop, the 2% novation rate option (190 lcd) has been selected for estimating residential per capital demand
rojection.
EWPCC per capita wastewater generation, including residential, commercial, and industrial ources and base infiltration is shown in Figure 4.20. This figure illustrates that wastewater eneration is expected to decrease from 323 lcd in 2006 to 298 lcd in 2031.
ra
p
Jresponse to rep
Ssg
4.24
150
Figure 4.20 - Total SEWPCC per Capita Projection
170
190
210
230
270
290
310
330
350
370
1980 1990 2000 201 2060
SEW
PCC
(lcd
)
250
0 2020 2030 2040 2050
Year
January Pumpage (lcd)Model
298 lcd
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
4.2.1.5 SEWPCC DWF Projection
Using the population projections and the per capita DWF projection, DWF estimates for the 2031 design year and up to 2050 were developed as shown in Figure 4.21.
4.25
WF is projected to increase over time from the present value of 50.4 ML/d (including Windsor Park in 2005) to 68.4 ML/d in 2031 using a population of 229,800 and a per capita, wastewater
sage of 298 lcd. This trend continues, producing a DWF or 79.3 ML/d in 2050.
.2.1.6 DWF Diversions
s noted in Table 4.9, the SEWPCC service area DWF projection is based on the assumption that the Windsor Park District will be e future.
his study also loo e NEWPCC either in the winter time, or continuously, and in addition, what the impact would be if the combined ewer districts (that is Cockburn, Baltimore, Mager and Metcalf) are also diverted. Figure 4.22
s the location and relative size of these Districts in the SEWPCC service area.
Total SEWPCC Wastewater Projection
90
30
40
50
60
1980 1990 2000 2010 2020 2030 2040 2050 2060Year
Was
tew
ater
(MLD
) 70
80ModelJanuary Pumpage (MLD)
68.4 MLD
2031
Figure 4.22 - Location and Size of Combined Sewer Districts Figure 4.21 - SEWPCC DWF Projection to 2050 (including Windsor Park)
D
u
4
Ain the SEWPCC service area continuously in th
ked at scenarios in which Windsor Park is diverted to thT
sillustrate
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
4.26
ulation is mption in this district was also analyzed and scaled up 18.5% to 8 lcd) in the winter. Based on this analysis, the estimated DWF
four
Average Annual Overflows = 7Range: 2 to 17
N COMBINED SEWERDISTRICTS
ALEXANDERARMSTRONGASHASSINIBOINEAUBREYBALTIMOREBANNATYNEBOYLECLIFTONCOCKBURN/CALROSSIECOLONYCORNISHDESPINSDONCASTERDOUGLAS PARKDUMOULINFERRY ROADHARTHAWTHORNEJEFFERSON EASTJEFFERSON WESTJESSIELAVERENDRYELINDENMAGERMARIONMETCALFEMISSIONMOORGATEMUNROENEWTONPARKSIDEPOLSONRIVERRIVERBENDROLANDSELKIRKSTRATHMILLANST. JOHN'SSYNDICATETUXEDOTYLEHURSTWOODHAVEN
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10111213141516171819
20a20b21222324252627282930313233343536373839404142
1
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89
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1112
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17
18
19
20a
20b
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
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71
72
CSO_dists; ms\01\0575
72
72 Windsor Park
404.5 ha274.9 ha
354.8 ha
804.6 ha
41.3 ha
Combined SewerBoundary
To put in perspective the size of these areas, Windsor Park is 404 ha and has a population of roughly 12,300 people. Analysis of 1996 and 2001 census data indicates this pop
Figure 4.22 – Location and Size of Combined Sewer Districts
relatively stable. Water consuaccount for base infiltration (4from Windsor Park is about 3.1 ML/d. It is assumed that this will remain constant into the futureto the year 2031.
A similar analysis was done on the four combined sewer districts, which together have a population of 38,430 and an area of 1,475 ha. Water consumption records in these areas were analyzed and scaled up to reflect the 18.5% average infiltration rate across the SEWPCC service area in winter. The analysis produced an estimated DWF of 10.8 ML/d from these
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
districts. The estimated DWF from each Combined Sewer District is:
Mager 6.2 ML/d
Cockburn 2.3 ML/d
• Baltimore 2.0 ML/d
Metcalf 0.3 ML/d
The effects of some potential DWF diversions on the projection to the year 2050 are shown in igure 4.23. Different combinations of diversions from the combined sewer districts and Windsor
rovide different projections.
•
•
•
FPark could p
0
10
20
30
40
50
60
70
80
90
1980 1990 2000 2010 2020 2030 2040 2050 2060
4.27
Figure 4.23 - Effects of DWF Diversions on Projections to 2050
Year
Pum
ping
(MLD
)
Historic
DWF Projection
With Out CS Districts
Without Windsor Park District
68.4 MLD
57.6 MLD
65.3 MLD
2031
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
Table 4.10 – Effect of Diversions on SEWPCC DWF Projection to 2031 and 2050
Case
ions)
Without Windsor Park
District
Without Combined
Sewer Districts
Without Windsor Park & Combined
Sewer Districts
Option (No Divers
Base
Estimated SEWPCC Projection ML/d in 2031
68.4 65.3 57.6 54.5
Estimated SEWPCC Projection ML/d in 2050
79.3 76.2 68.5 65.4
Table 4.10 shows the effect of diverting of Windsor Park and the combined sewer districts on SEWPCC DWF for the years 2031 and 2050.
The range of options considered for the 2031 design year are:
• The base case year round flow to SEWPCC from Windsor Park and the combined sewer
districts giving a design DWF of 68.4 ML/d.
• Without Windsor Park the DWF would be 65.3 ML/d.
• Without the combined sewer districts the DWF would be 57.6 ML/d.
• Without Windsor Park and the combined sewer districts the DWF would be 54.5 ML/d.
These options give considerable flexibility to the City when considering how to divert wastewater. The merits of diverting wastewater depend upon other factors such as treatment processes at the SEWPCC and the NEWPCC, as well as sewer system capacity throughout both districts and the ability to convey to each of the plants without causing hydraulic problems in the system or unnecessary overflows.
4.2.1.7 Hourl
Using the six-minute pumping records (2005-2006) from SEWPCC an analysis was done on the diurnal variation of dry weather flow during a mid-winter period (February 2005). Figure 4.24 illustrates the SEWPCC flow pattern in the chosen period. This figure shows diurnal flow with two peaks during week days and one peak during weekends. An analysis of this pattern indicates that the hourly peaking factor is in the range of 1.5 to 1.6 for the SEWPCC service area. The lowest diurnal flow is about 40% of the DWF.
y DWF Peaking
4.28
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
4.29
4.2.2.1 Introduction
t the SEWPCC during two distinct periods of the year:
s entering the system can drive the temperature down, stressing the biological treatment.
e what the peak flow in the system will be in the future. Since DWF projections in this study are based on a projection that considers water
ll be shrinking in the future. The factors that affect WWF are independent of the factors that affect DWF, therefore estimating WWF as a multiple of DWF is
tions. d
120
0
20
60
80
100
Sunda
y
Monda
y
Tuesd
ay
Wed
nesd
ay
Thursd
aFrid
ay
Saturda
Flow
at S
EWPC
C (M
L/d)
40
y y
Figure 4.24 - Weekly Flow Pattern (February 2005)
4.2.2 Wet-Weather Flow (WWF) Projections
WWF projections are required to determine WWF peaks a
• During the spring melt, flows can stress the system hydraulically and, as well, cold inflow
• Year-round or summer peaks can stress the system hydraulically.
In the past, WWF has been described by using a peaking factor. This peaking factor is multiplied by the projected DWF to indicat
conservation, per capita DWF wi
inappropriate and could under estimate peak flow design requirements.
In this study the WWF and DWF analyses have been separated and each is projected independently. For WWF, the analysis also considered variability of possible future condiAt any given year in the future, there is a probability that a certain design flow will be exceede
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
due to WWF. The design of the plant can be based on selecting an appropriate design equency and duration of event.
.2.2.2 Policy Decision
arious design flows need to be selected for components at the SEWPCC. The design flows hould be based on realistic assumptions of return period and duration of flow to be handled.
o design pumping at the treatment plant, it is expected that the collection system will bring 1:5-ear one-day events to the SEWPCC which will need to be handled. A 1:5-year frequency event realistic since the this is the frequency of the sewer designs to prevent basement flooding. It expected that when flows are higher than a 1:5-year maximum day, overflows will occur in the ystem and therefore will not be transported to the SEWPCC. This decision was agreed upon ith the City at the July 6, 2006 workshop.
.2.2.3 Frequency Analysis
he methods used to analyze dry-weather flow to determine the frequency in the future were as llows:
WWF at the SEWPCC for each day was estimated by subtracting the D F estimate for m the total daily flow. Once the daily WWF for
each year was estimated, the per capita WWF was estimated by dividing by the historic ar. This analysis was done on pumping records from 1983 to 2005.
e verage and a 7-day moving average were considered in addition to the
• g averages.
• each of year-
fr
4
Vs
Tyisissw
4
Tfo
W•each year (based on winter pumping rates) fro
population for that ye
• The next step was to calculate the moving average WWF for several averaging periods; th30-day moving adaily (i.e., 1-day average) WWFs.
For each year, the maximum WWF was identified for each of the 1-, 7- and 30-day movin
A simple frequency analysis performed by calculating the estimated return period for the maximum annual WWFs. This frequency analysis was done for both spring and round periods. Spring was defined as WWFs between March 1 and April 30.
The frequency plots for SEWPCC WWF (in lcd) for both spring and year-round periods are shown in Figure 4.25 and Figure 4.26.
4.30
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
0
4.31
1,200
Maximum Day 1,000Max. 7-Day Moving Avg.
Max. 30-Day Moving Avg.
200
400
600
WW
F (lc
d)
800
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%Probability of Not Being Exceeded
Figure 4.25 - Spring WWF Frequency
0
200
400
600
800
WW
F (lc
d) 1,000
1,200
1,600
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%Probability of Not Being Exceeded
1,400 Maximum DayMax. 7-Day Moving Avg.Max. 30-Day Moving Avg.
Figure 4.26 – Year-Round WWF Frequency
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
4.2.2.4 Flow Frequency Distribution in 2031 Based on Historic Data Analysis
ased on historic data, WWF probability distributions for the 2031 design year were developed. igure 4.27 shows the expected distribution for spring peak flows and Figure 4.28 shows the ear-round peak flow distribution.
BFy
SEWPCC 2031 Spring
0
100
200
300
400
500
600
0% 10%
4.32
Figure 4.27 - Expected Distribution for Spring Peak Flows
Figure 4.2 ak Flows 8 - Expected Distribution for Year-Round Pe
20% 30% 40% 50% 60% 70% 80% 90% 100%Frequency Not Exceeded
SEW
PCC
Flo
w (M
LD)
Maximum Day dataMax. 7-Day dataMax. 30-Day data
0
100
200
300
400
500
600
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%Probability of Not Being Exceeded
SEW
PCC
Flo
w (M
LD)
Maximum Day dataMax. 7-Day dataMax. 30-Day data
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
4.2.2.5 Accounting for Potential Sanitary Sewer Overflows (SSO)
Planning-level analysis was performed to understand whether major SSOs may be occurring during high WWFs and whether this would impact the frequency analysis of WWFs developedpreviously. An analysis of past reco
rds and pumping capacities throughout the SEWPCC
collection system was performed in order to estimate potential historic SSOs. This information as then used to determine what WWF could be in the future if these SSOs were captured and rought to the SEWPCC.
ome key assumptions were made to do this analysis:
The first assumption was that I/I occurs uniformly across the South End collection area (Note: An I/I study occurring at this time is monitoring I/I throughout the system and will be able to develop actual numbers on I/I and will allow this assumption to be refined).
It is assumed that in the future the rate of inflow from the combined sewer overflows (CSO) districts will be maintained at the current 41.5 ML/d. The assumption is that CSO control will involve a strategy that will store the combined sewage and dewater it at a rate of 41.5 ML/d. If the pumping at the Mager district is increased from 41.5 ML/d, the peaks at the SEWPCC would increase by the same amount.
o develop the SSO analysis, the capacity of the pump stations throughout the area that ontribute flow to the SEWPCC were obtained and the tributary area for each of these pump tations was estimated. The tributary area was estimated by reviewing air photos to estimate e percent of ac mping stations
nd their associated tributary areas estimated were:
The CSO districts (Mager, Baltimore, Cockburn/Calrossie). The maximum pumping limit at Mager is 41.5 ML/d.
D’Arcy pumping station includes the separated area west of the river and south of the Crane/Willow districts. Pumping capacity for this area is assumed to be 90 ML/d.
The Crane and Willow areas are sanitary sewer areas without sump pumps. Crane, which accepts Willow District flows, has a pumping capacity of 20.6 ML/d.
A Windsor Park separate sewer also does not have any major sump pump area. The pumping capacity to the interceptor for Windsor Park is assumed to be 10 ML/d.
The rest of the area that has been designated as South St. Vital/South St. Boniface includes some sump pump areas such as Pulberry; however, it is assumed that there is no pumping limitations in this area. Figure 4.29 shows the 2005 major pump areas in the SEWPCC catchment area.
wb
S
•
•
Tcsth tual developed area in each of the subcatchment areas. The pua
•
•
•
•
•
4.33
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
ill be the first areas to have pumping limitations. As expected, combined sewer overflows will occur first, before any sanitary sewer
SEWPCC is 160 ML/d. The next major limitation in the area was at the D’Arcy pumping station, which, assuming I/I is distributed evenly across the area, would become limiting at 90 ML/d. At
C exc istricts
SE with the expected lines
t st ma urly flow
a jThiSSO of as much as 105 ML/d could be occurring. Most of this (80 ML/d) is expecte D’Arcy. With no limitations in the system the flow at the SEWPCC could be as high as
The analysis has determined that the CSO districts w
Figure 4.29 - 2005 Pumped Areas in the SEWPCC Catchment
overflows. Windsor Park becomes limiting at 10 ML/d when the expected pumping rate at the
this time, the flow to the SEWPCC will be 245 ML/d. Therefore, when flows at the SEWPCeed 245 ML/d, we would expect that D’Arcy will be overflowing. The Crane/Willow D
become limiting at 21.6 ML/d when the SEWPCC pumping rate is at 250 ML/d. No other system is expected to become limiting before the SEWPCC pumping rate of 364 ML/d (the capacity of
WPCC) is met. Figure 4.30 illustrates the flow arriving at the SEWPCCflow that could be arriving at the SEWPCC without SSOs. The difference between the twois he amount of SSOs occurring, either at D’Arcy or at Windsor Park. It is likely that the va
jority of the SSO volume occurs at D’Arcy (50-80%). Using this relationship, the horecord at the SEWPCC for a July 2005 event (the week of June 26 to July 2, 2005) was
d usted. Figure 4.31 illustrates the adjustment occurring during the major storm in July of 2005. s adjustment indicates that during peak flows at SEWPCC when 350 ML/d is occurring, an
d to occur at
4.34
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
455 ML/d. This analysis was also done for the spring of 2006 and for events occurring in the spring of 2005, the summer of 2004, the summer of 2002 and the summer of 2000. The
stimated amount of SSOs occurring during these events for the maximum hour and for the maximum day was calculated. The flows for the largest events occurring in each year were
djusted upward. Table 4.11 shows the adjustments in maximum hourly and maximum daily ows for major events occurring over the past ten years.
able 4.11 – Adjustments to Peak Flows to Account for SSOs
d in
e
afl
T
4.35
This analysis was used to adjust each of the flows in the frequency analysis done presentethe previous section. Figures 4.32 and 4.33 illustrate the adjusted frequency analysis for both year-round and spring events. Only the maximum daily flows are large enough to be impactedby this analysis. The longer duration (7-day, 30-day) frequency analysis is not expected to be different when accounting for SSOs.
Events PeakSSO
EstimateAdjusted SEWPCC¹ Peak SSO Estimate
Adjusted SEWPCC¹
Peak Factor Max Hour/ Max Day Comment
1993 259 70 329From 2000 TetrES Analysis
1997 Spring 171 171 342 Assume 50% Shed2000 332 85 417 262 24 286 1.46 Records2002 244 5 249 Estimate
2004 Spring 347 103 450 240 17 257 1.75 Records2004 Summer 346 102 448 250 10 260 1.72 Records
2005 350 106 456 272 59 331 1.38 Records
Spring 2006 348 104 452 253 14 267 1.69Records -Not used in Freq Analysis
1.60 Average1) To consider full capture of SSOs
Hour Peak (ML/d) Day (ML/d)
Note: these could change with better I/I information expected from SE I/I study
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
4.36
Figure 4.30 - Flow Arriving at SEWPCC and Expected Flow Without SSOs
0
100
200
300
Existing Systemno SSO
400
Pote
ntia
l Tot
al F
low
(ML/
d)
500
600
700
0 50 100 150 200 250 350 400Arriving @ SEWPCC
(ML/d)
300
2005 Summer Total Flow
050
100150200250300350400450
SEW
PCC
(ML/
d)
500
Sunday
Monday
Tuesday
Wednes
day
Thursday
Friday
Saturd
ay
Flow
at
SSOSummer WWFDWF
Figure 4.31 - Adjustment During 2005 Summer Storm
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
0
100
200
300
400
500
600
700
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%Probability of Not Being Exceeded
SEW
PCC
Flo
w (M
LD)
Maximum Day SSO Occurring SSO adjusted data
Maximum Day data
Max. 7-Day data
Max. 30-Day data
4.37
Figure 4.32 - Frequency Analysis Accounting for Potential SSOs – Annual in 2031
0
100
200
300
400
500
600
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%Frequency Not Exceeded
SEW
PCC
Flo
w (M
LD)
Maximum Day SSO Occurring adjusted dataMaximum Day dataMax. 7-Day dataMax. 30-Day data
Figure 4.33 - Frequency Analysis Accounting for Potential SSOs – Spring in 2031
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
4.2.2.6 Estimated Hourly Wet-Weather Peak
The hourly and daily flow records for the past five years were analyzed to determine a peaking factor to estimate hourly flow based on the daily maximum flow. On average, the wet-weather hourly peaking factor was 1.6 times the maximum flow each year. To estimate the frequency of maximum hourly events for each year, multiply the maximum day event times 1.6.
4.2.2.7 Sensitivity Analysis of Limiting I/I in New Areas
The areas which are being developed after 2006 are expected to have less I/I than the average across the existing SEWPCC service area. Sensitivity analysis was done to determine how less I/I in these areas would reduce the peak flows to the plant during wet-weather conditions. The peak flows for the 1:5 maximum day event in 2031 were modified for various limited I/I scenarios are presented in Table 4.12. For a 1:5 maximum day event in 2031, assuming the I/I in the new areas is limited to 25% of the I/I currently across the SEWPCC service area, would be 300 ML/d. The first spring under the same conditions, the peak flow would be 237 ML/d. Maximum hour event entering the SEWPCC sewer system would be expected to be 480 ML/d (1.6 x maximum day).
T imum ay Events in 2031
able 4.12 - Effects of Limiting I/I in New Areas for 1:5-Year Maximum Hour and MaxD
WWF Year
WWF Spring
100% 553 345 25595% 548 342 25390% 543 339 25185% 538 336 24980% 533 333 24775% 528 330 24570% 523 327 24365% 519 324 24160% 514 321 23955% 509 318 23750% 504 315 23545% 499 312 23340% 494 309 23135% 489 306 22930% 485 303 22625% 480 300 22420% 475 297 22215% 470 294 22010% 465 291 2185% 460 288 2160% 455 285 214
New Areas Per Cent of Current
WWF
Maximum DayMax Hour (1.6 X Day)
4.38
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
4.2.2.8 WWF Diversions
If the combined sewer districts and/or Windsor Park are diverted during the summer months then peak flows could be reduced. All of the combined sewer districts in the SEWPCC pass through the Mager District Pumping Station. The City estimated the capacity of this station at 41.5 ML/d. Wet-weather peak events could be reduced by diverting combined sewage to the
mmer and spring thaws for maximum hour, maximum day, seven-day, The historic flow data (1983-2005) was reviewed
develop SEWPCC maximum winter and minimum flow factors. The minimum month, week nd day flows for winter, spring and summer were determined from the distribution of annual istoric values for these averaging period on a litres/capita/day basis for each season. The
seasonal values with a 20% (1 in 5 year) probability of not being exceeded were identified along with the median of annual DWF. The multiplication factors are the ratio of the seasonal flow and the median DWF. The maximum winter and minimum design flows are calculated by multiplying the 2031 DWF by the various factors.
The spring and summer flows were determined based on assumption for I/I for the future. Table 4.13 summarizes the maximum and minimum flow factors.
NEWPCC.
For Windsor Park, the total pumping rate to the SEWPCC is assumed to be 10 ML/d. The impact of diverting these districts on peak SEWPCC flows can be determined by subtracting these maximum pumping rates from the estimated design peak flows. The maximum day peak flow is estimated at 309 ML/d for the SEWPCC area. Diverting the combined sewer districts may decrease this to about 270 ML/d. An additional diversion of the Windsor Park district may reduce this to 260 ML/d.
The benefit of WWF diversions are complex and must be considered in the context of other studies such as the NEWPCC Master Plan and CSO Control studies.
4.2.3 Maximum and Minimum Flows
A summary of peak suand 30-day averages are shown in Table 4.13. toah
4.39
SEWPCC UPGRADING/EXPANSION PRELIMINARY DESIGN REPORT Population and Flow Projections March 31, 2008
4.40
Table 4.13 - Estimated Maximum and Minimum Flows in 2031
Flow (ML/d)Winter Spring Summer Winter Spring Summer
Average Day 1.3 1.3 68.4 88.9 88.9Month¹ 1.02 69.8 111 132Week¹ 1.08 73.9 143 178Day¹ 1.16 79.3 224 300Max
Factors
Hour¹ 1.6 127.0 358.4 480Month² 0.91 1.01 1.00 62.2 69.1 68.4
d summer are based of assumption for I/I for the future. This is discussed in tors analysis was not used to develop this flows
Week² 0.88 0.88 0.93 60.2 60.2 63.6Day² 0.81 0.73 0.81 55.4 49.9 55.4Hour² 0.40 0.40 0.40 22.2 20.0 22.2
Notes68.4 ML/d is the adjusted DWF for 2031Max/Min hourly flows are determined relative to the corresponding Max/Min daily flow
Min
1) Maximum flows in Spring anan earlier sub-section. Peak fac2) Minimum month, week, day factors based on SEWPCC historic data (on L/c/d basis) and:factors = (minimum flow with a 20% (i.e., 1 in 5 year) probability of not being exceeded) / (median ADWF).