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June 9, 2021
Cody Flammond, PE
City of Bozeman
20 E. Olive Street
Bozeman, MT 59715
RE: UPS Bozeman Parcel Distribution Water System Requirements
Mr. Flammond,
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 and fire suppression service line.
Water Usage
Two methods were used to estimate the peak daily demand for domestic water use.
1. 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 77 anticipated employees, the daily peak demand for domestic water use is 1,001 gallons
per day.
2. The other method is by comparing water usage to the existing facility in Bozeman. In analyzing the
last 5 years of water use records at this facility, the months from December to May were used in
order to exclude irrigation demand from the analysis. It is shown that the average volume per day of
domestic water used is 385 gallons per day for the approximately 12,600 SF building. The new
proposed structure is 35,100 SF and by method of direct comparison, the anticipated water
consumption for domestic use is estimated to be 1,073 gallons per day.
The peak daily demand for irrigation is 590 gallons per day based on an estimated usage in the month of
July.
Water Service Line Sizing
Service stubs from the municipal main have been provided into the subject property by the underlying
subdivision. There exists a 4” for domestic use and a 6” for fire suppression. Because of the existing
Yellowstone Pipeline easement along Royal Wolf Way and the full circulation around the building, both of
the proposed fire and domestic service lines exceed the maximum length of 150’ allowed by 38.410.070.B. as
they are currently 210’ from the water main connection.
Per plumbing code, the water system must be sized for peak demand based on fixture counts which is
estimated to be 80 gpm. The design pressure at the point of use is to be no less than 20 psi. Based on the
hydrant flow test conducted on 1/13/2021, the static water pressure from the municipal system is 48 psi.
Considering the approximate head losses through 210 lf of 2” copper pipe (13 psi), backflow preventer (12
psi) and the water meter (5 psi), the resulting water pressure is below the 20 psi minimum. It is proposed that
the existing 4” D.I. domestic service line be extended to approximately 10’-20’ from the building and then
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reduce down to the 2” copper service line for the riser within the building. This will reduce the head loss
from the service line to the main down to approximately 2.2 psi resulting in adequate pressure at the point
of use.
The low municipal system pressures will require that the fire service line be equipped with a booster pump
regardless of the head loss along the service line. These head losses will be accounted for in the design and
sizing of the fire sprinkler pump.
Sincerely,
Adam Schlegel, PE