HomeMy WebLinkAboutWater-Sewer Flow Memo
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Technical Memo
To: City of Bozeman
From: Daniel Stewart
Date: April 9, 2025
Re: Water and Sewer Flows - Nelson Meadows Lots 21 and 22, Block 1 – Exception
Health
Job: 10875
Exceptional Healthcare will be developed on Lots 21 and 22, Block 1 of the Nelson Meadows
Subdivision. The purpose of this memo is to demonstrate the water and wastewater flows for
the site.
Wastewater Flows
The sanitary sewer flows for the Nelson Meadows subdivision were calculated in the “Nelson
Meadows Subdivision Water and Wastewater Report” dated February 2018 by Morrison-
Majerle. The total wastewater generated for the M-1 zoned subdivision is 960 gallons per day
per acre. A peaking factor of 3.87 was in the report resulting in a peak hour flow of 3,715
gallon per day per acre.
The Exceptional Healthcare site is 3.78 acres. Using the Nelson Meadows design criteria of
960 gallons per acres, the sewer design capacity for the site is 3,629 gallons per day with a
peak hour flow of 14,044 gallons per day. The development is a medical facility with 19 beds
and 40 employees. Utilizing Table 3.1-1 in Circular DEQ 4 classified as medical hospital, the
typical wastewater flow is 165 gpd/bed and 10 gpd/employee.
The calculated wastewater flow for the Exceptional Healthcare site is:
Average Sewer Demand = 165 gpd/bed x 19 beds plus 10 gpd/employee x 28 employees
= 3,135 gpd plus 280 gpd = 3,415 gpd
Peak hour flow rate = 3,415 gpd x 3.87 = 13,216 gpd
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The estimated wastewater flow from the Exceptional Healthcare site is less than the than the
design capacity of the site.
Water Usage
The water design report for Nelson Meadows computed the average daily flow rate be 170
gallons per day for the equivalent population. The equivalent population from the report is
749. The proposed development is 3.78 acres and 5.44% of the Nelson Meadows
subdivision. The population equivalent for the site is 40 with an average daily flow rate of
6,800 gallons per day.
Water Demand
Average Daily Flow Rate = 165 gpd/bed x 19 beds plus 10 gpd/employee x 28 employees
= 3,135 gpd plus 280 gpd = 3,415 gpd
Maximum Daily Flow Rate = 3,415 x 2.3 = 7,855 gpd
Maximum Hour Flow Rate = 3,415 x 3.0 = 10,245 gpd
The estimated water demand for the Exceptional Healthcare site is less than the than the
design water demand for the site.
Fire flow demand will be a maximum of 1,500 gallons per minute per IFC regulations. The
water design report for Nelson Meadows also anticipated and modeled fire flows of 1,600
gpm at a minimum pressure of 20 psi for the development in addition to maximum day
demands. The proposed facility includes a building with a sprinkler system and aligns with the
assumptions and design of the existing system.
M O N TANA
LICENS E DPROF
E
SSIONAL E N G INEERDANIEL B.
STEWART
No. 90803 PE
04/09/25
niel, 1:1