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Water and Sewer Memo:
for
N 3rd Duplexes
Gallatin County, Montana
July, 2021
Prepared For:
302 Partners, LLC
Prepared By:
Hyalite Engineers, PLLC
Brett Megaard, PE
L:\213568\Engineering Reports\Water and Sewer Report Memo PLAN.doc Page 1
N 3RD DUPLEXES
ENGINEER’S WATER AND SEWER MEMO
Owner: 302 Partners, LLC
2304 North 7th Ave.
Bozeman, MT 59715
Introduction
This report provides an estimate of the peak-hour sanitary sewer demand as well as the
average and max day demands of domestic water usage for the proposed site development.
The City of Bozeman Design Standards and Specifications (March 2004) was used as the
primary guideline for this stormwater drainage design.
General Design
The proposed development of the site will contain two duplexes, each with two bedrooms.
Each duplex will have its own 1” copper water service and 4” SDR 26 PVC sewer service.
The sewer services will be connected to the 8” main that runs down North Third Avenue. The
sewer services will be ran at a minimum slope of ¼-inch per foot. Cleanouts will be provided
at each bend as well as at the building. Water services will be ran off of the 10” water main in
West Beall Street since the water main in North Third Avenue is only a 4” water main. Each
water service will have a curb stop and box 1 foot into the property. Water services are to be
1” diameter to allow for the potential use of domestic supply for a fire sprinkler system.
Sewer Demands
Assuming an average daily flow of 2.11 people per dwelling with 89-gallons per capita per
day:
(2.11 people per dwelling) X (4 dwellings) = 8.44 people
(8.44 people) X (89 gallons per person per day) = 751.16 gallons per day
Using a peaking factor of 4.42 calculated from equation 10-1 from DEQ Circular 2:
(751.16 gpd) X 4.42 = 3,320.13 gpd (2.31 gallons per minute)
Water Demands
Assuming 2.11 people per dwelling with an average daily usage of 170-gallons per person:
(2.11 people per dwelling) X (4 dwellings) = 8.44 people
(8.44 people) X (170 gallons per day) = 1,435 gallons per day
Using a maximum day to average day ratio of 2.3:1 from City of Bozeman Design Standards:
(1,435 gpd) X 2.3 = 3,300 gallons per day