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cushingterrell.com
April 30, 2026
Development Review Engineer
City of Bozeman
20 E. Olive Street
Bozeman, MT 59715
RE: Whitefish Credit Union Water and Wastewater Memo
To whom it may concern:
The purpose of this memo is to address city code Section 38.410.070 – Municipal water, sanitary sewer and
storm sewer systems. The proposed project includes a domestic water, fire suppression, and sanitary sewer
service line.
Domestic Water
Based on the fixture counts for the proposed building the water demand is 32 gallons per minute. Using the
total distance of piping to the furthest fixture, a domestic water line and meter size of 1.5 inches was
selected. This water service will not serve irrigation demand as that will be a separate connection to the
existing irrigation well.
Fire Suppression
A new fire suppression service line is proposed for the building as well. Based on fire flow data provided by
the City of Bozeman, the nearest existing hydrant (#2681) has a static water pressure of 78 psi and a fire flow
of approximately 4,000 gpm at 20 psi. This data was used to size the proposed 6” fire service line for the
building. No booster pumps for domestic or fire suppression system are anticipated.
Wastewater
Utilizing guidance from Montana DEQ Circular 4, a typical flow rate of 13 gallons per employee per day can
be used to estimate wastewater flow. The same was used in this estimate for domestic water use. With their
58 employees, the daily peak demand for domestic water use is:
Daily Demand = 13 gpd * 58 employees = 754 gallons per day.
Using an 8 hour average work day, this flow results in approximately:
Average flow = 754 gpd / (8 hours/day * 60 minutes/hour) = 1.57 gallons per minute.
Using a peaking factor of 4.0, an expected peak flow would be:
Peak Flow = 4*1.57 gallons per minute = 6.28 gallons per minute.
The proposed sanitary sewer service to this building is a 4” pvc pipe sloped at 2% which has a full flow
capacity of 0.26 cfs or 117 gallons per minute which exceeds the anticipated peak flow for the building. The
existing sanitary sewer main that the service line will connect to is an 8” pvc main sloped at 0.4%, which has a
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75% flow capacity of 0.704 cfs or 316 gallons per minute, which is sufficient capacity to service the proposed
building.
If questions or additional information is required, please contact me at 406.922.7111 or
AdamSchlegel@CushingTerrell.com.
Sincerely,
Adam Schlegel, PE
Civil Engineer
cc: WFCU_BOZ File