HomeMy WebLinkAbout007 - Water and Sewer Demands Design Report - Page 2 of 3 INTRODUCTION The Compass Apartment project proposes to develop Lot 5C of the Amended Plat of Lot 5, Annie Subdivision, Phase 2. The proposed layout of Lot 5C consists of a 5 story, 112 unit apartment building, an access driveway and parking lot, and associated landscaping areas and retention facilities. The property is located within the City of Bozeman limits and is currently zoned R-5. The property is fronted on one side by North 27th Ave, water and sanitary sewer mains are located within North 27th Ave. and water/sewer services are proposed to serve the development 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 = 2.11 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 (112 dwelling units) Average Day Demand = 112 d.u. x 2.11 persons/d.u. x 170 gpcpd = 40,174 gpd = 27.89 gpm Maximum Day Demand = 27.89 gpm x 2.3 = 64.14 gpm Peak Hour Demand = 27.89 gpm x 3.0 = 83.67 gpm
Design Report - Page 3 of 3 Sanitary Sewer Design Load The population estimates of 2.11 people per dwelling unit, and residential flow rate of 89 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 2.11 persons per household the equivalent population is calculated. Connection: Equivalent Population = (2.11 persons/dwelling unit)(112 units) = 236.32 persons Harmon Formula: Peaking Factor = (18 + P0.5)/(4 + P0.5) where: P = Population in thousands Peaking Factor = (18 + 0.236320.5)/(4 + 0.236320.5) Peaking Factor = 4.12 Assumed infiltration rate = 150 gallons/acre/day = 150 (2.262 acres) = 339.3 gal/day The peak flow rate is calculated by multiplying the City's design generation rate of 89 gallons per capita per day by the population, multiplying by the peaking factor, and adding the infiltration rate: Peak Flow Rate = 89 gpcpd (236.32 persons) (4.12) + 339.3 gpd = 86,993.11 gpd = 60.41 gpm = 0.135 cfs \\Files\Active\Projects\2023\23006847.00\Reportsnarratives\Water & Sewer\23006847.00 - Water And Sewer Demands.Docx