Chapter Population and Demand Forecast Contents Demographic Data Water by bobbybrull

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									Chapter 3 – Population and Demand Forecast – Contents
3.1      Demographic Data.....................................................................................................................3-1
3.2      Water Use Characteristics .........................................................................................................3-1
           Production and Peaking Factor .........................................................................................3-2
           Customer Categories and Consumption..........................................................................3-5
           Non-Revenue Water and Leakage ..................................................................................3-11
           Water Use Factors and ERUs ...........................................................................................3-11
3.3      Demand Forecast......................................................................................................................3-12
           Demand Forecast Methodology ......................................................................................3-12
           Demand Forecast Results .................................................................................................3-13
           Demand Forecast with Climate Change Impacts .........................................................3-15
Tables
Table 3.1.          Projected Demographics ..............................................................................................3-1
Table 3.2.          Water Production Summary (2004-2007 average in Mg) ........................................3-2
Table 3.3.          Peaking Factors .............................................................................................................3-4
Table 3.4.          Connections by Customer Category (Retail Only)...................................................3-6
Table 3.5.          Average Metered Water Consumption 2004-2007 (Mg) 1.......................................3-7
Table 3.6.          Customers with Highest Water Use (2005-2006 Average Consumption in Mg)3-10
Table 3.7.          Non-Revenue Water (Mg) .........................................................................................3-11
Table 3.8.          Water Use Factors and ERUs (2004-2006 Average)................................................3-12
Table 3.9.          Projected Demand.......................................................................................................3-14
Table 3.10.         Forecasted Climate Variables Compared to Historic Averages...........................3-16
Table 3.11.         Demand Under Two Climate Change Scenarios....................................................3-17
Figures
Figure 3.1.         Water Production by Source (2004-2007 Average)...................................................3-3
Figure 3.2.         Water Production Monthly Distribution (2004-2007 Average) ..............................3-3
Figure 3.3.         Annual Production (1998-2007) ..................................................................................3-4
Figure 3.4.         Monthly Distribution of Water Consumption (2004-2007 Average) .....................3-8
Figure 3.5.         Water Consumption by Customer Category (2004-2007 Average) .......................3-8
Figure 3.6.         Retail Connections and Consumption Comparison (2004-2007 Average) ...........3-9
Figure 3.7.         Demand Forecast Methodology................................................................................3-13
Figure 3.8.         Average Day and Maximum Day Demand Forecast.............................................3-14
Figure 3.9.         Average Day Demand Forecast Details (with additional conservation) ............3-15
Figure 3.10.        Climate Change Effect on Peak Season Increased Use (PSIU) .............................3-17
Appendix – (CD only)
3-1      Planning Data and Demand Forecast Technical Memorandum (HDR)




City of Olympia                                                       3-i                            2009 – 2014 Water System Plan
 1                                3. Population and Demand Forecast

 2

 3   Accurate data about projected water demand is essential for long-term water system planning.
 4   This chapter presents the Utility’s forecasts of population, households, employment and water
 5   demand. Following a review of historical and projected demographic data is a summary of use
 6   characteristics including production, consumption and related factors. The chapter concludes
 7   with a demand forecast for the next 50 years based on the demographics and water supply
 8   characteristics. The demand forecast is given with and without additional conservation
 9   measures, as well as two scenarios accounting for potential climate change impacts on demand.


10   3.1      DEMOGRAPHIC DATA
11   Demographic data presented here includes population, single-family households, multi-family
12   households and employees. Table 3.1 shows the historical and projected demographics at
13   specific planning horizons from 2007 to 2058.
14   Forecasts to 2030 are based on the Thurston Regional Planning Council (TRPC) October 2007
15   demographic projection. Forecasts beyond 2030 were extrapolated by the Utility for this Plan.
16   See Appendix 3-1 for more information on how these demographics were developed and a
17   breakdown of the demographics by pressure zone.
18                                      Table 3.1.        Projected Demographics
                                                         Single-Family             Multi-family
           Year                   Population              Households               Households          Employment
     2007 (Actual1)                     53,220                   15,785                     8,075             56,000
     2014 (Plan Yr 6)                   63,800                   17,900                    11,800             62,200
     2028 (Plan Yr 20)                  77,500                   22,300                    14,500             73,000
     2058 (Plan Yr 50)                 104,800                   35,600                    17,500            101,000
19   1.   This is the most recent year for which an entire year of historical data was available.



20   3.2      WATER USE CHARACTERISTICS
21   This section describes the water use characteristics used in making the demand forecast:
22        •   Production and peaking factor
23        •   Customer categories and consumption
24        •   Water balance, non-revenue water and water balance
25        •   Water use factors and ERUs




     City of Olympia                                            3-1                      2009 – 2014 Water System Plan
                                                                                 3. Population and Demand Forecast



 1   Production and Peaking Factor
 2   Olympia produces water from McAllister Springs and six wells, as described in Chapter 2.
 3   Table 3.2 shows average production over the last four years, by source and by month.
 4   (Production information is not shown for Indian Summer Well 20 (S12), scheduled to go online
 5   in September 2008.) The total average annual production has been 2,953 million gallons (Mg).
 6   Nearly 84 percent of the production is derived from McAllister Springs. As is typical with most
 7   water utilities, production peaks in the summer months of May through October. Figure 3.1
 8   and Figure 3.2 show this same information graphically, and Figure 3.3 shows the annual
 9   production for each year from 1998 to 2007.
10                Table 3.2.        Water Production Summary (2004-2007 average in Mg)
                                                                                             Shana
                                       Kaiser       Allison        Allison     Hoffman        Park
                   McAllister          Well 1       Well 13        Well 19      Well 3       Well 11
       Month      Springs (S01)        (S03)         (S09)          (S11)       (S08)        (S10)         Total        Percent
      Jan                   192               0             2              1           0            0          195        6.60%
      Feb                   180               0             0              0           0            0          180        6.09%
      Mar                   192               0             1              4           0            0          197        6.67%
      Apr                   189               1             8              9           0            3          209        7.07%
      May                   186               0           17             15            0           26          244        8.26%
      Jun                   217               6           13             25            0           28          288        9.77%
      Jul                   286              13           19             32            1           35          385       13.04%
      Aug                   275              12           21             30            0           37          376       12.73%
      Sep                   209              12           16             20            0           19          276        9.34%
      Oct                   181               2           13             12            0            4          213        7.21%
      Nov                   183               0             3              5           0            0          191        6.48%
      Dec                   191               0             4              4           0            1          199        6.75%
      Total               2,479              46          117            157            1          153        2,953      100.00%
      Percent           83.97%           1.54%        3.95%          5.33%       0.02%         5.19%      100.00%
11   Note: Nine years of production data was analyzed, however this table uses the most recent four years in order to
12   focus on current trends.




     City of Olympia                                         3-2                     2009 – 2014 Water System Plan
                                                                                       3. Population and Demand Forecast


1                                   Figure 3.1.      Water Production by Source (2004-2007 Average)


                                                                                               Kaiser Well 1 (S03)
                                                                                                      46 MG
                                                                                                       2%

           McAllister Springs (S01)
                  2,479 MG                                                                        Hoffman Well 3 (S08)
                      84%                                                                                1MG
                                                                                                          0%

                                                                                               Allison Well 13 (S09),
                                                                                                       117MG
                                                                                                         4%
                                                                                                      Shana Park Well 11
                                                                                                            (S10)
                                                                                                           153 MG
                                                                                                             5%

                                                                                        Allison Well 19 (S11)
                                                                                               157 MG
                                                                                                 5%
2
3

4                         Figure 3.2.           Water Production Monthly Distribution (2004-2007 Average)

                              400                                          385
                                                                                 376


                              350



                              300                                    288
                                                                                         276


                              250
                                                               244
            Million Gallons




                                                         209                                       213
                                    195            197                                                               199
                              200                                                                          191
                                          180


                              150



                              100



                               50



                                0
                                    Jan   Feb      Mar   Apr   May   Jun   Jul   Aug     Sep       Oct     Nov       Dec
5
6




    City of Olympia                                                  3-3                  2009 – 2014 Water System Plan
                                                                                                         3. Population and Demand Forecast


 1                                                     Figure 3.3.         Annual Production (1998-2007)

                               3,500
                                                                                   3,285
                                          3,161       3,177                                                            3,129
                                                              3,080                                                            3,034
                               3,000                                       2,913           2,916
                                                                                                    2,809     2,832



                               2,500
             Million Gallons




                               2,000




                               1,500




                               1,000




                                500




                                  0
                                          1998        1999    2000         2001    2002    2003      2004     2005      2006   2007
 2
 3   Table 3.3 gives the peaking factors from 1998 to 2007. The peaking factor has ranged from 1.8
 4   to 2.5, and has averaged 2.0 for the most recent four years. Note that the demand forecast
 5   presented later in this chapter uses a slightly higher peaking factor of 2.3. This is halfway
 6   between the average of the most recent four years and 2.5, which Olympia used in its 2004
 7   Water System Plan based on the State Department of Health (DOH) design manual.
 8                                                             Table 3.3.           Peaking Factors
                                                               Average                   Peak Day                 Peaking
                                               Year           Day (mgd)            (mgd)         Date              Factor
                                        1998                     8.7                19.2      7/29/1998             2.2
                                        1999                     8.7                16.4      7/12/1999             1.9
                                        2000                     8.4                15.5      8/7/2000              1.8
                                        2001                     8.0                16.6      8/10/2001             2.1
                                        2002                     9.0                16.2      8/14/2002             1.8
                                        2003                     8.0                15.6      7/29/2003             2.0
                                        2004                     7.7                19.5      7/20/2004             2.5
                                        2005                     7.8                15.0      8/6/2005              1.9
                                        2006                     8.6                16.1      7/6/2006              1.9
                                        2007                         8.3           15.1       7/11/2007               1.8

                                        2004-2007 Avg                8.1           16.4            n/a                2.0
 9                                     Note: Data is presented for ten years to show a lengthy history; the average for the
10                                     most recent four years is shown to focus on current trends.




     City of Olympia                                                                3-4                     2009 – 2014 Water System Plan
                                                                    3. Population and Demand Forecast



 1   Customer Categories and Consumption
 2   Olympia has six retail customer categories. Each category has standard connections and
 3   irrigation-only connections. The City also sells water wholesale to the City of Lacey and
 4   Thurston Public Utility District No. 1 (PUD). Prior to June 2005, Olympia provided retail
 5   service to customers in the PUDs service area. Since May 2005, Olympia has sold water
 6   wholesale to the PUD, which in turn provides water service to its customers.
 7      •   Single-family. Detached residential buildings serving a single family, duplex, triplex,
 8          or fourplex.
 9      •   Multifamily. Residential buildings such as apartment buildings or condos that serve
10          multiple households.
11      •   Commercial. Business and governmental customers.
12      •   Municipal. City of Olympia facilities.
13      •   Political Subdivision. Includes quasi-governmental customers such as Intercity Transit,
14          Port of Olympia and schools.
15      •   State. State of Washington facilities.
16   Table 3.4 gives the number of connections for each customer category from 1997 to 2007. Most
17   connections are either single-family (85%) or commercial (10%).
18   Average consumption, by customer category and by month, over the last four years is provided
19   in Table 3.5. The largest share of water consumption is accounted for by the single-family
20   customer category (40%), followed by commercial (20%), and multifamily (15%). These
21   collectively represent 75 percent of consumption.
22   Figure 3.4 and Figure 3.5 show this same information graphically.
23   Actual monthly consumption of water may differ slightly from the data presented in Table 3.5
24   and Figures 3.4 and 3.5. Most water meters are read bi-monthly, and consumption is assigned
25   to the month in which the meter is read.




     City of Olympia                                 3-5                 2009 – 2014 Water System Plan
                                                                                                                                     3. Population and Demand Forecast



                                              Table 3.4.       Connections by Customer Category (Retail Only)
                                                                                             Number of Connections
                                                                                                                                                             2004-2007 Avg
                            1
     Customer Category            1997          1998        1999        2000     2001         2002     2003         2004    2005      2006     2007            #          %
                    Standard       13,074        13,359     13,796      13,901   14,127       14,404   14,768   15,122      15,201    15,492   15,742          15,389 84%
 1. Single Family   Irrigation        134          142         150        148       150          151      161         161     166       170       182               170 1%
                    Total          13,208        13,501     13,946      14,049   14,277       14,555   14,929   15,283      15,367    15,662   15,924          15,559 85%
                    Standard          554          573         574        576       563          595      610         622     643       644       660               642 3%
 2. Multifamily     Irrigation           16            17          18      18           17        17       18          20      22        22           23            22 0.1%
                    Total             570          590         592        594       580          612      628         642     665       666       683               664 4%
                    Standard        1,459         1,454      1,457       1,456     1,468       1,374    1,495       1,510    1,528     1,549    1,572           1,540 8%
 3. Commercial      Irrigation        218          233         248        239       243          257      259         271     282       291       298               286 1.6%
                    Total           1,677         1,687      1,705       1,695     1,711       1,631    1,754       1,781    1,810     1,840    1,870           1,825 10%
                    Standard             34            33          53      59           58        57       58          57      55        56           56            56 0.3%
 4. Municipal       Irrigation           32            33          38      50           50        52       50          50      48        53           51            51 0.3%
                    Total                66            66          91     109       108          109      108         107     103       109       107               107 0.6%
                    Standard             57            57          62      56           56        59       59          60      60        61           63            61 0.3%
 5. Political
                    Irrigation           26            27          29      16           30        33       30          30      32        32           30            31 0.2%
 Subdivision
                    Total                83            84          91      72           86        92       89          90      92        93           93            92 0.5%
                    Standard             75            74          85      93           95        91       94          95      97        97           97            97 0.5%
 6. State           Irrigation           18            20          34      41           47        49       50          53      56        56           53            55 0.3%
                    Total                93            94      119        134       142          140      144         148     153       153       150               151 0.8%
                    Standard       15,253        15,550     16,027      16,141   16,367       16,580   17,084   17,466      17,584    17,899   18,190          17,785 97%
 Total              Irrigation        444          472         517        512       537          559      568         585     606       624       637               613 3%
                    Total          15,697        16,022     16,544      16,653   16,904       17,139   17,652   18,051      18,190    18,523 18,827        18,398       100%
1.   In June 2005 the Thurston PUD became a wholesale customer. PUD retail is not included in demand forecasting.




City of Olympia                                                                      3-6                                                 2009 -2014 Water System Plan
                                                                                                                                                3. Population and Demand Forecast



                                          Table 3.5.            Average Metered Water Consumption 2004-2007 (Mg) 1
 Customer Category                          Jan         Feb         Mar         Apr         May         Jun      Jul        Aug      Sep        Oct      Nov     Dec      Total       Percent
                             Standard           64             81       48            96      71           105         77     190          83     116      59       73       1,064          39%
 1. Single Family            Irrigation       0.04            0.1     0.02            0.2     0.1            3          1        9          2       5      0.4      0.5          22           1%
                             Total              64             81       48             96      71          108         78     200          85     121       60       74      1,086          40%
                             Standard           29             29       37            34      29            28         31       42         30      35      26       28          376         14%
 2. Multifamily              Irrigation          1              0        0              0       1            1          3        3          4       2        1        0          15           1%
                             Total              29             29       37             34      30           29         34       44         34      36       26       28         391         15%
                             Standard           40             28       36            30      42            34         46       38         44      33      37       28          437         16%
 3. Commercial               Irrigation          1              1        0              1       3           10         14       31         18      21        3        2         105           4%
                             Total              41             29       37             31      45           44         59       69         62      54       41       30         542         20%
                             Standard            2              2        2              2       3            3          5        4          5       3        3        2          36           1%
 4. Municipal                Irrigation          0              0        0              1       1            1          3        5          4       3        0        0          18           1%
                             Total               2              2        2              3       4            4          8        9          9       6        3        2          54           2%
                             Standard            5              4        4              6       6            5          7        7          5       7        4        6          64           2%
 5. Political Subdivision    Irrigation          0              0        0              0       1            2          4        8          5       4        1        0          27           1%
                             Total               5              4        4              6       7            7         11       15         10      10        5        6          92           3%
                             Standard            8              7        7              7      10            8         11       17         10       9        8        6         106           4%
 6. State                    Irrigation          0              0        0              0       1            3          5        6          5       2        0        0          22           1%
                             Total               8              7        7              7      10           10         16       22         15      11        8        6         128           5%
 7. Lacey Wholesale                               0.1         5.1         4.4         6.1    12.6         16.4     29.1       27.3     24.2       17.8    10.8     11.5        165           6%
                    2
 8. PUD Wholesale                             18.6        16.5        17.3        14.7       18.1         20.7     24.5       27.2     22.2       19.8    19.5     19.5        238           9%
                             Standard          147        152         134         174        161          183      176        298      178        203     137      142       2,084          77%
                             Irrigation          2           1           1           3          7           20       30         61       38         36       7        3        210           8%
 Total
                             Wholesale          19          22          22          21         31           37       54         54       46         38      30       31        404          15%
                             Total             167         175         157         197        199          240      260        414      262        276     174      176      2,698         100%
 Percent                                       6%        7%        6%       7%         7%        9%         10%       15%       10%        10%        6%         7%       100%
1. Actual monthly distribution water use may differ somewhat since the month of consumption is based on meter read dates and many meters are read bi-monthly.
2. Prior to May 2005, Olympia provided retail service to customers in the PUD's service area. Since May 2005, Olympia sells wholesale water to the PUD, which in turn provides
    water service to the customers. Wholesale sales to the PUD are significantly higher than were retail sales. This difference may be related to leakage in the PUD's distribution
    system, meter inaccuracies, and/or other issues. Since the difference was large, and because future PUD demand is based on wholesale volumes, past PUD retail sales were
    not included in demand forecasting.




City of Olympia                                                                                   3-7                                                 2009 -2014 Water System Plan
                                                                                                       3. Population and Demand Forecast



1         Figure 3.4.                        Monthly Distribution of Water Consumption (2004-2007 Average)

                               450                                                                                       PUD Wholesale



                               400
                                                                                                                         Lacey Wholesale


                               350

                                                                                                                         State

                               300


                                                                                                                         Political Subdivision
             Million Gallons




                               250



                               200                                                                                       Municipal



                               150
                                                                                                                         Commercial


                               100
                                                                                                                         Multifamily

                                50

                                                                                                                         Single Family
                                 0
                                     Jan   Feb    Mar    Apr   May    Jun    Jul     Aug   Sep   Oct   Nov    Dec
2
3                              Note: Actual monthly distribution water use may differ since the month of consumption is based on meter read dates
4                              and many meters are read bi-monthly.

5         Figure 3.5.                        Water Consumption by Customer Category (2004-2007 Average)

                                                                             Commercial
                                                                                20%

                                                                                                        Municipal , 2%

            Multifamily Residential
                     15%                                                                                      Political Subdivision, 3%

                                                                                                                            State
                                                                                                                             5%

                                                                                                                    Lacey Wholesale
                                                                                                                          6%




                                                                                                               PUD Wholesale
                                                                                                                   9%




                                                     Single Family
                                                      Residential
6                                                        40%




    City of Olympia                                                                3-8                       2009 - 2014 Water System Plan
                                                                                         3. Population and Demand Forecast


 1   Comparing the percent of connections to the percent of consumption can be useful, since water
 2   consumption does not always follow the same proportion as customer connections. This
 3   comparison is shown in Figure 3.6. Three customer categories stand out in this comparison.
 4   Single-family has a much larger percent of connections (85%) compared to the percent of
 5   consumption (47% of retail consumption). Multifamily has a much smaller percent of
 6   connections (3.6%) compared to the percent of consumption (17% of retail consumption). This
 7   is because one multifamily connection serves many multifamily households. Commercial has a
 8   much smaller ratio of connections (9.9%) to consumption (24% of retail consumption).
 9   Figure 3.6.            Retail Connections and Consumption Comparison (2004-2007 Average)




                      90%
                            84.6%

                      80%


                      70%


                      60%


                      50%           47%
            Percent




                      40%


                      30%
                                                                    24%

                      20%                          17%

                                                             9.9%
                      10%                                                                                                 6%
                                            3.6%                                  2%                   4%
                                                                           0.6%               0.5%                 0.8%
                      0%
                            Single Family   Multifamily      Commercial     Municipal      Political Subdivision     State

                                                          % Connections           % Retail Sales
10
11
12   Customers with large water demand are of interest since their demand could have significant
13   impact on overall demand. This is particularly the case when the largest customers are
14   commercial and industrial customers. Table 3.6 summarizes water use for the 15 customers
15   with the highest water use for 2005 and 2006.
16   Given the nature of these customers, any changes in their future demand would likely be
17   reflected in the demographic projections; therefore no special treatment of these customers was
18   required for the demand forecast.




     City of Olympia                                                 3-9                        2009 - 2014 Water System Plan
                                                                                                              3. Population and Demand Forecast



1                         Table 3.6.         Customers with Highest Water Use (2005-2006 Average Consumption in Mg)
                                                                                                                                     Metered
                                                                                                 Total         Metered Water        Irrigation
      Rank                   Customer                                 Service Address         Consumption      Consumption        Consumption
       1         Evergreen State College                      2725 Kaiser Road NW                      63.5              63.5                  n/a
          2      Capitol Campus                               Various                                 40.91                27.6              13.3
          3      Saint Peter's Hospital                       Various                                 40.86                40.3               0.6
          4      LOTT Wastewater Treatment Facility           500 Adams Street NE                      32.6                32.6               n/a


          5      City Hall                                    900 Plum Street SE                       22.2                21.9               0.3
          6      Crown Beverage and Packaging                 1204 Fones Road SE                       19.4                19.4               0.0


          7      Thurston County Courthouse                   2000 Lakeridge Drive SE                  18.5                18.1               0.3
                 Complex
          8      Crowne Pointe Apartments                     2800 Limited Lane NW                     15.5                15.5               0.0
                 Cambridge1

          9      Apple Park Apartments                        3200 Capital Mall Drive SW               15.4                15.4               0.0
          10     Colonial Estates                             3700 14th Avenue SE                      13.0                 8.7               4.3
                                       1
          11     Capital High School                          2707 Conger Ave NW                       12.6                 2.7              10.0
          12     Capital Mall and Associated Stores           625 Black Lake Blvd SW                   12.4                 7.5               4.9


          13     Capital Medical Center                       3900 Capital Mall Drive SW               12.0                 9.4               2.6
          14     Westlakes Apartments (Dr. Harlan             1919 Evergreen Park Dr SW                11.7                 9.8               2.0
                 Bixby)
          15     Friendly Village MHP                         1111 Archwood Dr SW                      10.7                10.7               0.0
     1.   These accounts did not appear on the list of the largest 15 customers until 2006.




    City of Olympia                                                       3-10                                   2009 – 2014 Water System Plan
                                                                           3. Population and Demand Forecast




 1   Non-Revenue Water and Leakage
 2   The forecast of future demand includes a calculation of “non-revenue water,” which includes
 3   leakage and all other unmetered uses. Authorized uses of unmetered water include:
 4   firefighting and hydrant flushing, sampling, construction, water and sewer line flushing and
 5   testing, street cleaning and other maintenance. For this purpose, a simple calculation of
 6   production minus consumption was used for the past five years, as shown in Table 3.7. A more
 7   refined analysis of water loss is in Chapter 6, Water Conservation Program.
 8

 9                                     Table 3.7.      Non-Revenue Water (Mg)
                                                                           Non-Revenue Water
                                                                            Percent of       Percent of
                  Year          Production     Consumption     Quantity1   Consumption       Production
      2003                          2,916           2,680        236               8.80%           8.10%
      2004                          2,809           2,581        228               8.80%           8.10%
      2005                          2,832           2,616        217               8.30%           7.70%
      2006                          3,129           2,757        372              13.50%          11.90%
      2007                          3,034           2,713        321              11.80%          10.60%
      2004-07 Average               2,951           2,667        285              10.60%           9.58%
      1.       Production minus consumption.


10   Water Use Factors and ERUs
11   Water use factors were calculated for three customer categories: single-family, multifamily, and
12   industrial, commercial and institutional. Table 3.8 shows the data used for the calculations,
13   including the number of Equivalent Residential Units (ERUs) in each customer category.
14   ERUs are a method of representing water use by non-residential customers as an equivalent
15   number of residential customers. An ERU is the amount of water used by a single-family
16   household, which in Olympia is 198 gpd. The number of ERUs for each customer category is
17   obtained by dividing the consumption for a customer category by 198. Therefore, the single-
18   family customer category equates to 15,272 ERUs, the multifamily category to 5,506 ERUs, and
19   the industrial, commercial, institutional category to 11,460 ERUs.
20   Below are the key water use factors and how they were calculated:
21         •     198 gpd per single-family household. Single-family consumption (3,025,748 gpd)
22               divided by the number of households (15,272).
23         •     123 gpd per multifamily household. Multifamily consumption (1,090,241 gpd) divided
24               by the number of households (8,847).
25         •     41 gpd per employee. Industrial, commercial, institutional consumption (2,269,082 gpd)
26               divided by the number of employees (55,095).




     City of Olympia                                        3-11               2009 - 2014 Water System Plan
                                                                                    3. Population and Demand Forecast


 1                    Table 3.8.        Water Use Factors and ERUs (2004-2006 Average)
                                                                                    Consumption per
                                     Consumption          Households or               Household or              Number of
       Customer Category                (gpd)2             Employees                 Employee (gpd)              ERUs7
     Single Family (SF)                   3,025,748             15,2723                            1986            15,272
     Multifamily (MF)                     1,090,241               8,8474                            123             5,506
     Industrial, Commercial
                                           2,269,082                 55,0955                              41         11,460
     Institutional (ICI)1
 2   1.   This includes the following four customer categories: commercial, municipal, political subdivision and State.
 3   2.   Data Source: "WSP Monthly Consumption 2002 to 2006" and "WSP Data 1" spreadsheets provided by Utility
 4        staff.
 5   3.   Assumed to be the same as the number as single-family connections.
 6   4.   Based on data in Table 3.1. For 2006 9,122 multifamily households were estimated. The number of households
 7        for 2004 and 2005 were back-calculated using 4% annual growth rates.
 8   5.   Based on data in Table 3.1. For 2006 55,930 employees were estimated. The number of employees for 2004
 9        and 2005 were back-calculated using 1.5% annual growth rates.
10   6.   The City’s Equivalent Residential Unit (ERU) is 198 gallons per day.
11   7.   The number of ERUs in any customer category is calculated by dividing that category's water consumption by
12        the ERU value.


13   3.3      DEMAND FORECAST
14   Olympia’s Comprehensive Plan requires the Utility to reserve water supply rights for at least 50
15   years in advance of need, so that supplies can be protected from contamination or commitment
16   to lower priority uses (Policy PF 6.1). This section describes the methodology used in
17   developing the demand forecast, provides the results with and without additional conservation,
18   and shows how demand would vary under two climate change scenarios.


19   Demand Forecast Methodology
20   The methodology used to develop the demand forecast for retail consumption is illustrated in
21   Figure 3.7. The basic process is to combine demographic data with water use factors to
22   calculate customer demands. Demand components for non-revenue water, the PUD wholesale
23   water and Lacey wholesale water are then added to create the total average day demand. To
24   generate the total maximum day demand, a peaking factor is applied to all demands except the
25   Lacey demand. See Appendix 3-1, Planning Data and Demand Forecast Technical
26   Memorandum, for more information on the methodology.




     City of Olympia                                          3-12                      2009 - 2014 Water System Plan
                                                                    3. Population and Demand Forecast


 1                          Figure 3.7.    Demand Forecast Methodology




 2


 3   Demand Forecast Results
 4   Table 3.9 gives the projected demand, both without and with additional conservation. The
 5   forecast with additional conservation reflects the Water Conservation Program planned for
 6   2009-2014, as described in Chapter 6. The City’s conservation goal is to reduce water usage by 5
 7   percent per connection between 2009 and 2014. Therefore, the forecast with additional
 8   conservation reduces the water use factors by 0.83 percent a year for planning years 1 through
 9   6. By year 6, this reduction is equivalent to approximately 415,000 gallons per day in terms of
10   average-day consumption.
11   Olympia plans to continue conservation efforts beyond 2014. However, since the conservation
12   goals beyond 2014 are not yet defined, the water use factors are held constant for all years
13   beyond 2014 in the demand forecast.
14   Figure 3.8 shows the average day and maximum day demands, both with and without
15   additional conservation. Figure 3.9 shows the six components of the average day demand in
16   order to illustrate the relative impact of each component. Figure 3.9 uses demand with
17   additional conservation, since that is the demand the Utility expects to experience.




     City of Olympia                               3-13                 2009 - 2014 Water System Plan
                                                                                                                                              3. Population and Demand Forecast



1                                                                           Table 3.9.                  Projected Demand
                                  Demand Without Additional Conservation                                                            Demand With Additional Conservation
                                  Average Day Demand (mgd)       Max Day                                                          Average Day Demand (mgd)        Max Day
                                                                 Demand                                                                                           Demand
    Year                        Retail  PUD    Lacey1    Total     (mgd)                                                         Retail  PUD     Lacey1 Total      (mgd)
 2007
                    6.8      0.68          0.8     8.2            15.1          6.8     0.68        0.8      8.2                                                                                         16.1
 (Actual)
 2014
                    8.3      0.70            0     9.0            20.8          7.9     0.70          0      8.6                                                                                         19.6
 (Plan Yr 6)
 2028
 (Plan Yr          10.2      0.72            0    10.9            25.0          9.7     0.72          0     10.4                                                                                         23.6
 20)
 2058
 (Plan Yr          14.7      0.77            0    15.5            35.7        14.0      0.77          0 14.77                                                                                            33.6
 50)
 2
Note: Demands for Lacey are not included for the entire planning period since that wholesale agreement expires in June of
 3
2009, with an optional two-year extension.
 4
5                                              Figure 3.8.                Average Day and Maximum Day Demand Forecast

                             ADD without additional conservation           MDD without additional conservation               ADD with addtional conservation          MDD with additional conservation

                          40,000,000
                                         Actual            Forecasted




                          35,000,000



                          30,000,000



                          25,000,000
        Gallons per Day




                          20,000,000



                          15,000,000



                          10,000,000



                           5,000,000



                                    0
                                        2001



                                                    2006



                                                                   2011



                                                                              2016



                                                                                           2021



                                                                                                        2026



                                                                                                                      2031



                                                                                                                                      2036



                                                                                                                                                   2041



                                                                                                                                                               2046



                                                                                                                                                                            2051



                                                                                                                                                                                         2056




                                                                                                               Year
6
7                                ADD = Average Day Demand ; MDD = Maximum Day Demand.




      City of Olympia                                                                                    3-14                                         2009 - 2014 Water System Plan
                                                                                                                                   3. Population and Demand Forecast


 1      Figure 3.9.                                  Average Day Demand Forecast Details (with additional conservation)

                                                             Single Family          Multifamily      ICI             Non-Revenue            PUD          Lacey
                            16,000,000
                                            Actual             Forecasted




                            14,000,000



                            12,000,000



                            10,000,000
          Gallons per Day




                             8,000,000



                             6,000,000



                             4,000,000



                             2,000,000



                                    0
                                         2001



                                                      2006



                                                                     2011



                                                                             2016



                                                                                          2021



                                                                                                  2026



                                                                                                              2031



                                                                                                                           2036



                                                                                                                                     2041



                                                                                                                                                  2046



                                                                                                                                                             2051



                                                                                                                                                                    2056
                                                                                                           Year
 2


 3   Demand Forecast with Climate Change Impacts
 4   Water resource planners throughout the Pacific Northwest are increasingly attempting to
 5   account for the anticipated effects of long-term climate change on demands for water supplies.
 6   While there is now widespread acceptance among scientists, the public and water managers
 7   that climate change poses significant risks, there is still substantial uncertainty about the
 8   magnitude and timing of change, and how water demand will be affected.
 9   The University of Washington Climate Impacts Group (CIG) has analyzed forecasts from global
10   climate models to predict changes in temperature and precipitation in the Northwest region.
11   Results of these analyses were used to estimate potential effects on demand for water in
12   Olympia’s water service area.
13   A number of recent publications from the CIG were reviewed to identify expected climate
14   effects. Temperature and precipitation projections shown here are based on a report prepared
15   by CIG for the Portland Water Bureau in 2002. The report uses four separate models yielding a
16   range of possible outcomes. These results are similar to other results reported by CIG for
17   locations in western Washington and Oregon.
18   As shown in Table 3.10, the range of potential effects is considerable. In the case of
19   precipitation, forecasts vary from reduced precipitation to increased precipitation, with a
20   relatively large difference in possible outcomes. Temperature is forecast to rise under all
21   scenarios, but there is a substantial range in the size of possible temperature increases.




     City of Olympia                                                                              3-15                                      2009 - 2014 Water System Plan
                                                                             3. Population and Demand Forecast



 1           Table 3.10.      Forecasted Climate Variables Compared to Historic Averages
                                           2020                                        2040
          Month            Precipitation           Temperature         Precipitation           Temperature
        Jan
        Feb            100% - 120% of
                                                                  90% - 140% of historic
        Mar            historic
        Apr
        May                                       1.8 to 5.4      100% - 120%                 2.4 to 7.2
        Jun            70% to 160% of             degrees F                                   degrees F
        Jul            historic                   higher than                                 higher than
                                                  historic        75% - 110% of historic      historic
        Aug
        Sep
        Oct            90% - 140% of
        Nov            historic                                   90% - 140% of historic
        Dec
        Note: Shaded months are peak season as defined by City of Olympia. Comparison is with the historical
        period 1950-99.
        Source: Adapted from model projections reported in: Palmer, R. N. and Margaret Hahn, 2002, The Impacts
        of Climate Change on Portland’s Water Supply, An Investigation of Potential Hydrologic and Management
        Impacts on the Bull Run System, prepared for Portland Water Bureau.

 2   Given the variability in possible impacts of climate change, forecasting the effects on demand
 3   for water remains challenging. For purposes of this Plan, the Utility has developed estimates
 4   based on professional judgment, taking into account the range of precipitation and climate
 5   effects shown in Table 3.10. The analysis assumes that the primary impacts on demand would
 6   occur during the irrigation season, which extends from approximately May through October.
 7   Professional judgment was used to estimate potential increased demand on two metrics:
 8      •   Peak Season Increased Use (PSIU)
 9      •   Maximum Day Demand
10   PSIU is defined as the additional water used from May – October, above the normal “base
11   quantity” of demand; this is illustrated conceptually in Figure 3.10. The base quantity
12   represents indoor uses, and can be determined from billing records for the non-irrigation season
13   (November – April).




     City of Olympia                                       3-16                  2009 - 2014 Water System Plan
                                                                                                3. Population and Demand Forecast


 1           Figure 3.10. Climate Change Effect on Peak Season Increased Use (PSIU)
                                                                          Additional PSIU (climate change scenarios)



                   Total Annual Water Use (mg)
                                                                          Peak Season Increased Use - PSIU
                                                                          (May - October, current conditions)




                                                                           Base Use
                                                                           (Nov. - April - current conditions)


 2
 3

 4   For purposes of the demand forecast, two scenarios were developed:
 5       •   Scenario 1. Increased temperature and reduced precipitation cause an increase of 10
 6           percent in PSIU and an increase of 5 percent in Maximum Daily Demand (MDD).
 7       •   Scenario 2. Increased temperature and reduced precipitation cause an increase of 20
 8           percent in PSIU and an increase of 10 percent in MDD.
 9   Applying these two scenarios to the initial demand forecast (without conservation) yields the
10   results shown in Table 3.11.
11                                               Table 3.11.   Demand Under Two Climate Change Scenarios
                                                Demand Under Climate                                     Demand Under Climate
                           Base Demand1                 Scenario 1                                            Scenario 2
            Year            ADD         MDD      ADD           MDD                                        ADD            MDD
     2007 (Actual)               8.2     15.1        8.2           15.1                                         8.2          15.1
     2014 (Plan Yr 6)            9.0     20.8        9.1           21.0                                         9.1          21.2
     2028 (Plan Yr 20)          10.9     25.0       11.1           25.8                                        11.2          26.6
     2058 (Plan Yr 50)          15.5     35.7       16.1           38.4                                        16.7          41.2
     1. Base demand is without additional conservation.

12   It is currently anticipated that climate change effects will be gradual, allowing time for the
13   community and water system to adapt over periods of years and decades. Water management
14   options to respond to climate change will include continued improvements in water use
15   efficiency through the Water Conservation Program (Chapter 6); further development of the
16   Reclaimed Water Program (Chapter 7); and/or development of new sources of supply when
17   necessary (Chapter 5). The Utility will monitor demand and weather variables closely in
18   coming years in order to refine these initial scenarios and respond as necessary.




     City of Olympia                                                       3-17                      2009 - 2014 Water System Plan

								
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