HomeMy WebLinkAbout031 Water and Sewer Demands DESIGN REPORT
WATER AND SANITARY SEWER
DEMAND CALCULATIONS
HAYDEN VALLEY CONDOS
Prepared for:
Scenic Design Studio
8200 Saddle Mountain RD.,
Bozeman, MT, 59715
Prepared by:
Engineering and Surveying Inc.
1091 Stoneridge Drive • Bozeman, MT 59718
Phone (406] 587-1115 • Fax(406) 587-9768
www.chengineers.com • info@chengineers.com ,
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C&H Project No. 210795
INTRODUCTION ,
The Hayden Valley Condos Site Plan project proposes to develop Lot 2, Block 11 of Cattail Creek
Subdivision Phase 2A & 2B into two 4-plex buildings. The property is located in the City of
Bozeman and is zoned as R-3.
The property is fronted on two sides by City streets with Fen Way and Davis Lane being adjacent
to the east and west property boundaries, respectively. Water and sanitary sewer mains are
located within Fen Way and individual water and sanitary sewer services will connect to each of
the proposed buildings as shown on civil sheet C2.1.
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 (127 dwelling units)
Average Day Demand= 8 d.u. x 2.17 persons/d.u. x 170 gpcpd=2,951 gpd=2.05 gpm
Maximum Day Demand =2.05 gpm x 2.3 =4.72 gpm
Peak Hour Demand =2.05 gpm x 3.0 = 6.15 gpm
Design Report-Page 2 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 to the City of Bozeman Design Standards and Specifications. 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)(8 units) = 17.4 persons
Harmon Formula: Peaking Factor= (18 +PO 5)/(4 +Po.$)
where: P =Population in thousands
Peaking Factor= (18 + 0.01740-5)/(4 + 0.0170.1)
Peaking Factor=4.39
Assumed infiltration rate = 150 gallons/acre/day = 150 (0.5593 acres) = 83.9 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 (17.4 persons) (4.39) + 83.9 gpd = 5,003 gpd
3.47 gpm
0.008 cfs
Design Report-Page 3 of 3