HomeMy WebLinkAbout201397_Water Sewer Report_2022.02.15 Design Report - Page 2 of 3
INTRODUCTION
The Addison Place Condominium Site Plan project proposes to develop Lot 4 of the Baxter Lane
Subdivision. The proposed layout consists of one 20-plex condominium building, parking lot for
the development, and related stormwater and landscaping areas. The property is located within the
City of Bozeman limits and is currently zoned R-4.
The property is fronted on two sides by Thomas Drive and Sartain being adjacent to the eastern
and southern property boundaries, respectively. Water and sanitary sewer mains are located
within Sartain Street and individual water, fire, and sanitary sewer services will connect to the
proposed building as shown on civil sheet C3.0.
Water Distribution System Demands
The design parameters used herein are according to the City of Bozeman Design Standards and
Specifications Policy (DSSP) dated May 2017.
Average Daily Residential Usage = 170 gallons per capita per day
Average Population Density = 2.17 persons/dwelling unit
Average Day Demand (Peaking Factor = 1.0)
Maximum Day Demand (Peaking Factor = 2.3)
Peak Hour Demand (Peaking Factor = 3.0)
Water Demands (20 dwelling units)
Average Day Demand = 20 d.u. x 2.17 persons/d.u. x 170 gpcpd = 7,378 gpd = 5.12 gpm
Maximum Day Demand = 5.12 gpm x 2.3 = 11.78 gpm
Peak Hour Demand = 5.12 gpm x 3.0 = 15.36 gpm
Design Report - Page 3 of 3
Sanitary Sewer Design Load
The population estimates of 2.17 people per dwelling unit, and residential flow rate of 64.4 gpcd
used herein are according to2015 Wastewater Facility Plan. The peaking factor for the design area
is determined using the formula provided in the City of Bozeman Design Standards and
Specifications.
Using the city average of 2.17 persons per household the equivalent population is calculated.
Connection:
Equivalent Population = (2.17 persons/dwelling unit)(20 units) = 43.4 persons
Harmon Formula: Peaking Factor = (18 + P0.5)/(4 + P0.5)
where: P = Population in thousands
Peaking Factor = (18 + 0.04340.5)/(4 + 0.04340.5)
Peaking Factor = 4.327
Assumed infiltration rate = 150 gallons/acre/day = 150 (0.9093 acres) = 136 gal/day
The peak flow rate is calculated by multiplying the City's design generation rate of 64.4 gallons per
capita per day by the population, multiplying by the peaking factor, and adding the infiltration rate:
Peak Flow Rate = 64.4 gpcpd (43.4 persons) (4.327) + 136 gpd = 12,230 gpd
= 8.49 gpm
= 0.023 cfs
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