CHAPTER VI EXISTING AND FUTURE POPULATION PROJECTIONS

Transcription

1 COMPREHENSIVE SEWER PLAN CHAPTER VI EXISTING AND FUTURE POPULATION PROJECTIONS 6.1 POPULATION General Current and future population projections for areas that include the Alderwood Service Area have been independently developed by both the Puget Sound Regional Council (PSRC) and Snohomish County. These population projections are used for planning efforts that impact regional growth. The Snohomish County population projections are based on a parcel by parcel forecast of current and future zoning densities, whereas the PSRC population projections are based on U.S. Census data as broken down by Forecast Analysis Zone (FAZ). Both the County and the PSRC population projections were evaluated to determine the sewered and unsewered populations within the Alderwood Service Area. Both data sets appeared to have different strengths. The PSRC values tend to be more widely used to forecast regional growth trends. PSRC values were also used to size the Picnic Point WWTP and to estimate the Everett regional water demands. However, the County based forecasts provided insight as to where actual growth would occur and there by facilitated a more accurate vision of population growth rates between particular mini-basins. The individual analyses for the PSRC and the Snohomish County projections are located in Appendix C. In an effort to develop the most accurate population estimations for sewer modeling and CIP identification, a hybrid approach was taken to develop the intermediate and ultimate population projections for the District. The PSRC values were used for the baseline population and the Snohomish County values were used for the distribution of growth between and within mini-basins. Using these results in conjunction with GIS mapping techniques, the current and future populations were derived for each Alderwood minibasin Existing Residential Population and Sewer Connections There are approximately 30,499 residential accounts consisting of about 115,400 people and 1,075 accounts designated as commercial, industrial or municipal. These customers are located throughout the District with the highest density of users near city and urban centers. A breakdown of population distribution within the District was created and based on the PSRC Sub-County detailed forecast areas or Forecast Analysis Zones (FAZ) and then refined using Snohomish County growth rate projections. The PSRC is an association of cities, towns, counties, ports, and state agencies that serves as a forum for developing policies and making decisions about regional growth in the central Puget Sound region. The PSRC employs population projections in order to 6-1

2 COMPREHENSIVE SEWER PLAN meet the requirements of federal legislation and data needs for land use and transportation modeling. The PSRC released new forecasts in 2006 to replace the 2003 Regional Demographic and Economic Forecasts. The Regional Council employed a new forecasting model, the PSEF model, replacing the STEP 2002 model. The new regional forecasts extend out to 2040, while accounting for the recession that impacted the Puget Sound Region during the past several years. This study has accepted PSRC s build out conditions of 2040 as the ultimate projected population. Additional forecasts were developed using the agency s existing DRAM (Disaggregate Residential Allocation Model) and EMPAL ( Allocation Model) models, although the data inputs and model equations for the DRAM and EMPAL models were substantially updated since the versions. These additional forecasts also extend to Present day population estimates for the District were derived using a straight line regression analysis between the year 2000 and the year 2010 population projections presented by the PSRC. Refinement of this estimate was accomplished using the Snohomish County population projection values. Refinement was necessary because the growth in each FAZ between 2000 and 2010 will not likely occur at a uniform rate. The refinement process redistributes the total population change over a decade between sub-groupings of mini-basins that share the same major basin and FAZ. This refinement essentially allows for those mini-basins with more subdividable and developable parcels to receive a larger portion of the population distribution than a neighboring mini-basin that is already approaching its build out capacity. Not all households within the Alderwood Service Boundary are customers of the District. Some homes operate on private wells and/or septic systems. As a result, the sewered population is less than the total population. The difference between the sewered and unsewered population was calculated using the ratios from Snohomish County data sets and applying them to the refined PSRC projections Future Residential Population and Sewer Connections The PSRC has forecast populations for the years 2000, 2010, 2020, 2030, and Therefore, the population projections for 2012 and 2026 could be derived similarly to the present day population projection. Using a straight line regression analysis between the two nearest decades of PSRC data, the populations for the Alderwood service areas during the years 2012 and 2026 were estimated and then refined using Snohomish County s estimate of future projected growth areas. Like the present day estimate, the refinement process redistributed the total population change over a decade between sub-groupings of mini-basins that share the same major basin and FAZ. The estimated sewered and unsewered populations for 2002/3, 2006, 2012, 2026 and 2040 are shown in Table 6.1. The estimated sewered and unsewered populations for the same set of years are shown graphically in Figure

3 Basin North Creek Table 6.1 Alderwood Water & Wastewater District Sewered and Unsewered Population Estimates Mini-Basins 2002/ District King Cnty Sewered Sewered Sewered Sewered Sewered Name Name Population Population Population Population Population Population Population Population Population Population NC-1 ALDN ,250 1,234 1,346 1,330 1,540 1,529 1,585 1,585 NC-2 ALDN09 1, , , ,736 2,736 3,522 3,522 NC-3 SLWD Trib , ,459 1,717 4,391 4,391 7,146 7,146 NC-4 SLV NC-5 SLV004 1,127 1,127 1,150 1,150 1,168 1,168 1,218 1,218 1,272 1,272 NC-6 SLV NC-7 SLV NC-8 ALD032 2,568 1,776 2,706 2,663 2,889 2,847 3,297 3,259 3,840 3,840 NC-9 ALD6A , ,003 1,995 2,831 2,831 NC-10 ALD022 2,100 1,802 2,165 2,151 2,314 2,314 2,586 2,586 2,950 2,950 NC-11 ALD NC-12 ALD026 1,433 1,418 1,435 1,435 1,410 1,410 1,376 1,376 1,304 1,304 NC-13 ALD021 1,048 1,048 1,048 1,048 1,090 1,090 1,145 1,145 1,234 1,234 NC-14 ALD ,088 1,063 1,383 1,383 1,737 1,737 NC-15 ALD6C ,722 1,389 2,284 1,940 3,036 3,024 4,150 4,150 NC-16 ALD009 1,105 1,105 1,139 1,139 1,217 1,217 1,360 1,360 1,551 1,551 NC-17 ALD025 1,929 1,828 2,003 1,897 2,090 2,019 2,295 2,287 2,558 2,558 NC-18 ALD006B 1, ,293 1,262 3,233 2,264 4,858 4,498 6,555 6,555 NC-19 ALD023N 2,530 2,514 2,595 2,594 2,656 2,654 2,813 2,812 2,998 2,998 NC-20 ALD033 1,456 1,383 1,587 1,534 1,778 1,741 2,190 2,186 2,559 2,559 NC-21 ALD037 1,800 1,788 1,865 1,853 1,900 1,883 2,076 2,069 2,154 2,154 NC-22 ALD038 1, ,100 1,148 3,628 2,341 6,130 4,890 8,794 8,794 NC-23 ALD031 4,668 3,503 4,961 4,323 5,301 4,762 6,158 5,629 6,448 6,448 NC-24 ALD028 3,742 2,245 4,011 2,569 4,351 2,878 5,146 5,049 5,786 5,786 NC-25 ALDN ,422 1,422 NC-26 ALD041 2,479 1,988 2,589 2,171 2,678 2,479 2,986 2,931 3,166 3,166 NC-27 ALD011 1, ,130 1,098 1,097 1,095 1,071 1, NC-28 ALDN ,106 1,106 NC-29 ALD001A 1, ,380 1,000 1,770 1,394 2,475 2,182 2,909 2,909 NC-30 ALD ,050 1,050 1,125 1,125 NC-31 ALDN ,342 1,335 1,698 1,698 NC-32 ALD012 1,870 1,751 1,922 1,819 1,964 1,922 2,109 2,092 2,334 2,334 NC-33 ALD

4 Basin Table 6.1 Alderwood Water & Wastewater District Sewered and Unsewered Population Estimates Mini-Basins 2002/ District King Cnty Sewered Sewered Sewered Sewered Sewered Name Name Population Population Population Population Population Population Population Population Population Population NC-34 ALDN , ,166 2,129 3,572 3,572 5,050 5,050 NC-35 ALD013 1,784 1,702 1,845 1,764 1,911 1,867 2,100 2,076 2,392 2,392 NC-36 ALD035 1, ,831 1,123 2,007 1,338 2,415 2,386 3,050 3,050 NC-37 ALD , ,083 1,081 1,251 1,251 1,513 1,513 NC-38 ALDN ,124 1,124 1,456 1,456 NC-39 ALD034 1,834 1,757 1,882 1,846 1,915 1,880 2,040 2,040 2,139 2,139 NC-40 NCREK012 1,450 1,305 1,582 1,456 1,744 1,603 2,072 2,033 2,350 2,350 NC-41 ALDN ,012 1,012 1,279 1,279 North Creek Subtotal Swamp Creek 54,534 42,110 61,107 49,859 70,296 60,323 88,407 85, , ,185 SC-1 ALD018 2,511 1,807 2,821 2,144 3,244 2,843 3,906 3,882 4,373 4,373 SC-2 ALD018A 2,525 1,977 3,163 2,598 4,114 3,903 6,223 6,147 8,330 8,330 SC-3 ALD014A 1,090 1,062 1,186 1,159 1,303 1,278 1,660 1,629 2,046 2,046 SC-4 ALD014B 2,354 2,119 2,496 2,407 2,616 2,584 3,097 3,071 3,629 3,629 SC-5 ALDN ,626 1,023 3,321 3,246 5,077 5,077 SC-6 ALDN , ,265 1,549 4,433 4,068 6,680 6,680 SC-7 ALD003 1,401 1,330 1,502 1,438 1,604 1,566 1,958 1,931 2,345 2,345 SC-8 ALD12 2,105 1,051 2,458 1,474 3,006 2,177 4,406 4,152 5,883 5,883 SC-9 ALD020 2,718 2,507 2,977 2,907 3,303 3,273 4,271 4,250 5,313 5,313 SC-10 ALDN01 1,078 1,024 1,304 1,268 1,703 1,698 2,532 2,520 3,391 3,391 SC-11 ALD12A 1, , , ,243 2,194 2,784 2,784 SC-12 ALD015 3,660 3,226 3,715 3,400 3,665 3,383 3,719 3,641 3,760 3,760 SC-13 ALD016A ,160 1,141 1,683 1,683 SC-14 ALD039A , ,690 1,313 3,026 3,026 4,369 4,369 SC-15 ALD012B ,147 1,147 SC-16 ALD005 1,580 1,314 1,619 1,369 1,627 1,560 1,700 1,647 1,741 1,741 SC-17 ALD004 2,705 2,598 2,743 2,663 2,697 2,665 2,709 2,709 2,650 2,650 SC-18 ALD006 3,011 1,739 3,123 1,812 3,215 2,063 3,498 3,480 3,743 3,743 SC-19 ALD007A 1,831 1,097 2,066 1,447 2,715 2,593 3,830 3,659 5,224 5,224 SC-20 ALDN02 1, ,022 1,111 2,276 1,587 2,824 2,799 3,405 3,405 SC-21 ALD008 2,594 2,334 2,742 2,466 2,943 2,713 3,451 3,195 4,099 4,099 SC-22 ALDN000 1, ,400 1,173 3,486 2,111 5,610 5,610 8,004 8,004 SC-23 ALD010A 1, , SC-24 ALDN03 1,458 1,115 1,479 1,134 1,351 1,066 1,279 1,279 1,198 1,198

5 Basin Table 6.1 Alderwood Water & Wastewater District Sewered and Unsewered Population Estimates Mini-Basins 2002/ District King Cnty Sewered Sewered Sewered Sewered Sewered Name Name Population Population Population Population Population Population Population Population Population Population Swamp Creek Subtotal 41,419 30,269 46,592 35,479 54,439 45,284 72,717 71,094 91,790 91,790 Everett EV-1 ALDN10 7,188 6,469 7,596 6,909 8,215 7,787 9,579 9,470 10,878 10,878 Everett Subtotal 7,188 6,469 7,596 6,909 8,215 7,787 9,579 9,470 10,878 10,878 Picnic Point PP-1 ALDN ,009 1,010 1,319 1,319 PP-2 ALDN19 4,383 4,296 4,981 4,940 5,845 5,801 7,585 7,560 9,049 9,049 PP-3 ALDN PP-4 Picnic PP-5 ALDN21 1, , , ,359 1,293 1,464 1,464 PP-6 ALDN17 1,433 1,361 1,459 1,438 1,520 1,501 1,623 1,601 1,688 1,688 PP-7 Marina PP-8 ALDN14 3,058 3,000 3,148 3,116 3,212 3,184 3,562 3,555 3,930 3,930 PP-9 ALDN13 3,175 3,089 3,280 3,206 3,393 3,313 3,837 3,784 4,311 4,311 PP-10 ALD014C 1,122 1,010 1,201 1,181 1,412 1,394 1,876 1,846 2,389 2,389 PP-11 ALDN ,212 1,212 PP-12 ALDN20 5,963 5,249 6,168 5,460 6,414 6,188 7,312 7,275 8,274 8,274 PP-13 ALDN22 2,680 2,545 2,827 2,686 3,158 3,064 3,957 3,949 4,833 4,833 Picnic Point Subtotal 23,938 21,444 25,441 22,996 27,812 25,502 33,554 33,150 39,156 39,156 Little Bear Creek BC-1 Little Bear Creek Little Bear Creek Subtotal District 127, , , , , , , , , ,009

6 COMPREHENSIVE SEWER PLAN Figure 6.1 Alderwood Water & Wastewater District Population Forecast 300, , ,000 Population 150,000 Population Sewered Population 100,000 50, Year 6.2 EMPLOYMENT AND SEWER USAGE must be considered to accurately gauge the wastewater production from non-residential land use applications. The PSRC has projected employment growth rates for every decade within the FAZs between 2000 and Using straight line regression analysis between the two nearest decades, employment growth rates can be projected for any set of years within a FAZ. When these growth rates are applied to the acreage of commercially developable land in each mini-basin, employment projections for each mini-basin can be derived. The employment projections by mini-basin for the years 2002/3, 2006, 2012, 2026, and 2040 are shown in Table 6.2. It is assumed that all commercial accounts are connected to the sewer. 6-6

7 Table 6.2 Alderwood Water & Wastewater District Estimates Mini-basins 2002/ Basin North Creek District Name King Cnty Name NC-1 ALDN NC-2 ALDN NC-3 SLWDTrib NC-4 SLV NC-5 SLV NC-6 SLV NC-7 SLV NC-8 ALD NC-9 ALD6A NC-10 ALD022 1,612 1,684 1,852 2,345 2,834 NC-11 ALD NC-12 ALD NC-13 ALD NC-14 ALD NC-15 ALD6C NC-16 ALD NC-17 ALD NC-18 ALD006B NC-19 ALD023N NC-20 ALD NC-21 ALD NC-22 ALD NC-23 ALD NC-24 ALD NC-25 ALDN NC-26 ALD NC-27 ALD NC-28 ALDN NC-29 ALD001A ,933 2,593 NC-30 ALD040 1,568 1,622 1,772 2,303 2,801 NC-31 ALDN NC-32 ALD NC-33 ALD ,089 5,262 5,751 7,472 9,088 NC-34 ALDN NC-35 ALD NC-36 ALD NC-37 ALD ,396 NC-38 ALDN NC-39 ALD NC-40 NCREK012 1,793 1,853 2,026 2,632 3,201 NC-41 ALDN North Creek Subtotal 16,853 17,644 19,575 25,438 31,208 Swamp Creek SC-1 ALD018 1,400 1,421 1,499 1,898 2,488 SC-2 ALD018A ,429 1,887 SC-3 ALD014A

8 Table 6.2 Alderwood Water & Wastewater District Estimates Mini-basins 2002/ Basin Everett Picnic Point Little Bear Creek District Name King Cnty Name SC-4 ALD014B ,042 1,589 2,206 SC-5 ALDN SC-6 ALDN SC-7 ALD SC-8 ALD SC-9 ALD SC-10 ALDN SC-11 ALD12A SC-12 ALD ,134 1,504 SC-13 ALD016A SC-14 ALD039A SC-15 ALD012B SC-16 ALD ,079 2,417 SC-17 ALD SC-18 ALD SC-19 ALD007A SC-20 ALDN SC-21 ALD SC-22 ALDN SC-23 ALD010A SC-24 ALDN Swamp Creek Subtotal 9,055 9,570 10,830 14,885 19,451 EV-1 ALDN10 + 4,392 4,582 5,074 6,793 8,655 Everett Subtotal 4,392 4,582 5,074 6,793 8,655 PP-1 ALDN PP-2 ALDN PP-3 ALDN16 1,296 1,316 1,400 1,863 2,510 PP-4 Picnic PP-5 ALDN PP-6 ALDN17 2,497 2,535 2,697 3,588 4,836 PP-7 Marina PP-8 ALDN PP-9 ALDN PP-10 ALDN014C PP-11 ALDN PP-12 ALDN PP-13 ALDN Picnic Point Subtotal 5,482 5,589 6,002 8,154 11,109 BC-1 Little Bear Creek 3,559 3,680 4,022 5,226 6,356 Little Bear Creek Subtotal 3,559 3,680 4,022 5,226 6,356 District 39,341 41,065 45,503 60,496 76,779

9 COMPREHENSIVE SEWER PLAN 6.3 SCHOOLS The public and private schools within the Alderwood service boundary represent concentrated areas of wastewater production. The locations of schools within the Alderwood Service Area in relationship to the mini-basins are shown in Figure 6.2. Current student and staff population and projected growth within each mini-basin is shown in Table 6.3. All schools within the District are currently sewered with the exception of the Northshore Elementary No. 2 in the Little Bear Creek Basin. Student and staff growth rate was assumed to be consistent with overall mini-basin population growth rate. 6-9

10 School Location 132nd ST SE SR 52 7 I- 5 Picnic Point Basin 35th AVE SE South Everett Basin Basin Boundaries 51st AVE SE LEGEND: 148th ST SE SR 525 NORMA BEACH RD 164th ST SW Swamp Creek Basin 180th ST SW 180th ST SE 36th AVE W North Creek Basin I th ST SE 212th ST SW EVERETT BOTHELL HWY 196th ST SW MALTBY RD 220th ST SW I th ST SW 228th ST SW I-5 228th ST SE Little Bear Creek Basin 244th ST SW Alderwood Basins and Schools WATER & WASTEWATER DISTRICT Alderwood Water & Wastewater District Snohomish County, Washington 6.2

11 Table 6.3 Alderwood Water & Wastewater District Sewered Student Populations Mini-basins 2002/ District King County Sewered Sewered Sewered Sewered Sewered Basin Name Name Population Population Population Population Population North Creek NC-1 ALDN NC-2 ALDN NC-3 SLWD Trib NC-4 SLV001 2,511 2,626 2,806 3,271 3,795 NC-5 SLV NC-6 SLV NC-7 SLV NC-8 ALD NC-9 ALD6A NC-10 ALD NC-11 ALD NC-12 ALD NC-13 ALD NC-14 ALD NC-15 ALD6C NC-16 ALD NC-17 ALD NC-18 ALD006B NC-19 ALD023N NC-20 ALD NC-21 ALD NC-22 ALD NC-23 ALD NC-24 ALD NC-25 ALDN NC-26 ALD NC-27 ALD NC-28 ALDN NC-29 ALD001A NC-30 ALD NC-31 ALDN NC-32 ALD NC-33 ALD ,107 1,346 NC-34 ALDN NC-35 ALD NC-36 ALD035A NC-37 ALD NC-38 ALDN NC-39 ALD ,119 NC-40 NCREK NC-41 ALDN North Creek Subtotal 7,301 7,657 8,216 9,670 11,331 Swamp Creek SC-1 ALD SC-2 ALD018A ,063

12 Table 6.3 Alderwood Water & Wastewater District Sewered Student Populations Mini-basins 2002/ District King County Sewered Sewered Sewered Sewered Sewered Basin Name Name Population Population Population Population Population North Creek SC-3 ALD014A SC-4 ALD014B SC-5 ALDN SC-6 ALDN SC-7 ALD SC-8 ALD SC-9 ALD SC-10 ALDN SC-11 ALD12A SC-12 ALD SC-13 ALD016A SC-14 ALD039A SC-15 ALD012B SC-16 ALD ,139 SC-17 ALD SC-18 ALD SC-19 ALD007A SC-20 ALDN SC-21 ALD008A SC-22 ALDN SC-23 ALD010A SC-24 ALDN Swamp Creek Subtotal 3,344 3,509 3,770 4,454 5,237 Everett EV-1 ALDN10 3,426 3,555 3,755 4,263 4,824 Everett Subtotal 3,426 3,555 3,755 4,263 4,824 Picnic Point PP-1 ALDN PP-2 ALDN ,029 1,169 1,323 PP-3 ALDN PP-4 Picnic PP-5 ALDN PP-6 ALDN PP-7 Marina PP-8 ALDN PP-9 ALDN PP-10 ALD014C PP-11 ALDN PP-12 ALDN PP-13 ALDN Picnic Point Subtotal 1,388 1,439 1,519 1,723 1,947 Little Bear Creek BC-1 Little Bear Creek Little Bear Creek Subtotal District 15,459 16,160 17,260 20,110 23,339

13 COMPREHENSIVE SEWER PLAN 6.4 COMMERCIAL CUSTOMERS The highest volume commercial customers served by the District sewers are shown in Table 6.4 to provide examples of the peak water consumption. In general, a peak water user will also be a peak wastewater generator. Flow projections commonly consist of the three components of residential, commercial, and schools, which have been presented earlier in this chapter. The commercial segment is generally represented in terms of number of employees, which was the forecast mechanism used by PSRC. In addition to employee populations, some jurisdictions have used square footage of commercial building space as a forecasting tool. Both approaches have limitations that require some manipulation. Recognizing that the wastewater generated per employee at a hotel will be significantly greater than flows per employee at an office building or warehouse, the plan separated commercial flows from the District s twenty largest water customers. For further explanation on this topic refer to the discussion in Chapter 7, Model Construction and Capacity Analysis. 6.5 INDUSTRIAL CUSTOMERS There are four (4) industrial dischargers within the Alderwood service area that generate industrial type wastewater. These customers include the following: Name Location/Address Testing/Sampling Req ts Neah Power Systems th Ave SE, Suite 161, Bothell ph and flow Bayer Health Care nd Street SW, Lynnwood ph and flow Amgen Corp rd Dr SE, Bothell ph and flow Crane-Eldec Corp th Ave West, Lynnwood ph, flow, chromium, copper, lead, nickel, FOG Self-monitored industrial waste reports are submitted to the District and to King County each month. 6-13

14 Average Water Consumption (2004- Customer Name Customer Type 2006) Annual (MG) Daily (gpd) Avalon Bay/ Wildwood Multi-family ,438 On the Green Multi-family ,117 AWWD Sewage Treatment Plant Non-Residential ,246 Archstone Communities Multi-family ,899 Keeler's Corner Apartment Multi-family ,396 Harbour Pointe Golf Course Non-Residential ,694 The Renaissance Multi-family ,850 Amgen, Inc. Non-Residential ,923 Canyon Springs Apartments Multi-family ,793 Philips Ultrasound, Inc. Non-Residential ,744 Tamaron Ranch Apartments Multi-family ,316 Stone Meadows Farms Multi-family ,017 ICOS Corp. Non-Residential ,715 The Settlement Multi-family ,097 FSC/Fox Ridge Association, LLC Multi-family ,525 Amberwood Village Apartments Multi-family ,358 Floral Hills Multi-family ,544 Brookwood Apartments Multi-family ,238 Madison Park Apartments Multi-family ,022 Wear to Live, LLC Multi-family ,704 Notes MG = million gallons; gpd = gallons per day 1) Twenty customers with largest consumption 2) Source: District billing data, Table 6.4 Largest Water Customers ( ) 1