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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


-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


-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


-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


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)


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


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


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


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


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


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%


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.


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


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


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.


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.


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)


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


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


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


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 )


Cleaning (2 )

ToiletLeaks (14 )

Showers (49 )

Faucets (20 )

Bath (23 )

2004 (217 LCD)

Toilet Leaks (14 )

Toilets (41 )

Washers (37 )


Cleaning (2 )

Showers (48 )

Faucets (20 )

Bath (23 )

2019 (196 LCD)

ToiletLeaks (14 )

Toilets (30 )

Washers (33 )


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


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


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


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




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


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


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


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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CSO_dists; ms\01\0575

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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


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


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


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


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


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


1,400 Maximum DayMax. 7-Day Moving Avg.Max. 30-Day Moving Avg.

Figure 4.26 – Year-Round WWF Frequency


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


SEW

PCC

Flo

w (M

LD)

Maximum Day dataMax. 7-Day dataMax. 30-Day data


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


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


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


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


0

100

200

300

400

500

600

700


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


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


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


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).

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