Demand Forecast

6, 10 & 20 Year Demand Projections

Future water demands were estimated based on historical demands plus the demand from the University Apartments and an additional 30 new equivalent residential units (ERUs) per year.  Demand estimates for new ERUs are listed below.  Future peak hour demands from new ERUs were estimated based on a peak hour to peak day peaking factor of 2.

Average Day Demand                630 gpd/ERU          

Peak Day Demand                  1,700 gpd/ERU          

Peak Hour Demand                3,400 gpd/ERU          

In estimating future demands, it was assumed that separate irrigation would not be available and that the distribution of new connections between the pressure zones would be similar to what has occurred in the past (refer to Table 3-4).  Actual demands will vary depending on the progress of developments that are being proposed. 

Demands from the additional 84 units planned at the University Apartments was added to the future estimated demands based on 2015 consumption for Building A through F of the University Apartments.  These buildings (A through F) account for 120 units.  In 2015, the average consumption was 69 gpd/unit, while the peak day was 103 gpd/unit, and the peak hour was 0.16 gpm/unit.

Table 3-15 includes a water demand forecast for the system and Pressure Zone 3.  A separate forecast was not included for Zone 4 since new connections are not being allowed in this zone until additional pumping, storage and distribution system improvements are made to this zone.  The cost of these improvements makes it more likely for the lower zones to develop first.  The lower zones include sufficient undeveloped land to accommodate 20-years of growth.

Table 3-15 also includes a demand forecast with projected water savings from the Water Use Efficiency Program.  Projected water savings are based on a 3% reduction every 6 years for single-family residential customers.  Single-family residential customers make up approximately 70% of the system demand.  This results in an overall water savings of approximately 0.35% per year

Without Water Savings


Demands without projected water savings from Water Use Efficiency Program as follows
  1. System
  2. Zone 3
  3. Zone 4
Classification
2016 2016 + Apartments 2022 2026 2036
Projected Additional ERUs
n/a n/a 180 300 600
Additional University Apartments ERUs n/a 84 n/a n/a n/a
Average Day Demand (Gallons Per Day)
912,000 918,00 1,031,000 1,107,000 1,296,000
Peak Day Demand (Gallons Per Day)
2,073,000 2,082,000 2,388,000 2,592,000 3,102,000
Peak Hour Demand (Gallons Per Minute)
2,850 2,860 3,320 3,600 4,310

With Water Savings


Demands with projected water savings from Water Use Efficiency Program are as follows.
  1. System
  2. Zone 3
  3. Zone 4
Classification 2016 2016 + Apartments 2022 2026 2036
Projected Additional ERUs
n/a n/a 180 300 600
Additional University Apartments ERUs n/a 84 n/a n/a n/a
Average Day Demand (Gallons Per Day)
912,000 918,000 1,010,000 1,068,000 1,205,000
Peak Day Demand (Gallons Per Day)
2,073,000 2,082,000 2,338,000 2,501,000 2,885,000
Peak Hour Demand (Gallons Per Minute)
2,850 2,860 3,250 3,470 4,010
Table 3-15
Water Demand Forecast

Notes:

1. Future consumption for the University Apartments is based on an average day demand of 69 gpd/unit, a peak day demand of 103 gpd/unit, and a peak hour demand of 0.16 gpm/unit. These values are based on 2015 demands from Buildings A-F.

2. Number of customers and demands for Zone 3 include all zones except Zone 1 and 1a.

3. Water demand forecasts are based on the highest recorded average day, peak day and peak hour demands through 2016, plus demand projections for future single-family residential customers without separate irrigation, plus demands from the University Apartments at buildout.

4. New connections are not being allowed in Zone 4 until additional pumping, storage and distribution system improvements are made to this zone.    

5. Demands with projected water savings are based on a 3% reduction every 6 years for single-family residential customers. Single-family residential customers make up approximately 70% of the system demand.

6. Demands without projected water savings from water use efficiency program will be used in the system analysis.


Demands Per Acre


Single-family demand projections per acre are listed below. The projections are based on 3.5 units per acre, which is similar to Terraced Estates (423 units per 120 acres) and Mount Adams Estates (79 units per 22 acres).

Time Without Separate Irrigation With Separate Irrigation
Average Day Demand 2,200 gallons per day per acre, or 2.5 acre-feet per acre per year 1,200 gallons per day per acre, or 1.3 acre-feet per acre per year
Peak Day Demand 6,000 gallons per day per acre, or 4.1 gallons per minute per acre 2,450 gallons per day per acre, or 1.7 gallons per minute per acre