HomeMy WebLinkAbout05.2 Anticipated Water Demand and Service Size 2300 Regent Street, Suite 207
Missoula, Montana 59801
P: 406.542.2849
www.jmengineering.net
July 1, 2021
City of Bozeman
Certified Building Official
RE: University Crossing Water Service Size
This letter confirms the intended water service sizes for two new apartment buildings at S 19th
Ave. and Kagy Blvd. (University Crossing). The buildings will consist of 59 new one-bedroom
apartment buildings, 23 in the North Building and 36 in the South Building. Each building will have
its own water service line. Fixture unit calculations are attached in the City of Bozeman Water
Service Calculation Worksheets. Both buildings will require a service line above the maximum in
the worksheets based on total fixture units and/or maximum length of pipe from the meter. Below
is an analysis of the required meter size and main size for each building.
Based on the 2018 UPC (current City of Bozeman adopted plumbing code) Appendix A, the water
service size will be based on estimated demand in GPM, acceptable pressure loss through the
system and meter, and available street pressure. Annotated chart A103.1(1) (attached below)
shows the estimated demand of each building in GPM from the fixture unit totals outlined in the
City of Bozeman Water Service Calculation Worksheets. Based on these demands and an
acceptable pressure drop across the meter, Chart A 102.2 (attached below) shows the required
meter size for each building; 3” for the North Building and 4” for the South Building. Assuming a
building supply pressure range of 46-60psi, the pressure drop associated with a maximum of
250ft of pipe in the North Building and 275ft in the South Building, and the use of relatively
smooth ferrous pipe for the building mains, the main line size for each building can be achieved.
Chart A 105.1(2) shows an acceptable pressure drop per 100ft of pipe length at a 3” main line
size for the North Building and at a 4” main line size for the South Building.
Below is a summary of the intended building water service sizes:
North Building:
Meter Size: 3”
Main Supply Line Size: 3”
South Building:
Meter Size: 4”
Main Supply Line Size: 4”
Sincerely,
John Melvin, PE
CHART A 105.1(2)
Residential (2018 IRC)
City of Bozeman Water Service Calculation Worksheet
Project Address: ___________________________________ Property Owner: ________________________________
General Contractor: _______________________________________________________________________________
Permit Number: _______________ Proposed Water Meter Size: ______________
UPC Table 610.3 Standard Design Water Supply Fixture Units
Appliances and Fixtures Fixture Units # of Fixtures Total
Bathtub or combo tub/shower (1/2” fill valve) 4.0 X ________ = ________
Bath Tub (3/4” fill valve) 10.0 X ________ = ________
Shower (per head) 2.0 X ________ = ________
Clothes washer 4.0 X ________ = ________
Dishwasher 1.5 X ________ = ________
Hose Bibb 2.5 X ________ = ________
Additional Hose Bibb (each) 1.0 X _______ = ________
Lavatory Sink 1.0 X ________ = ________
Kitchen Sink 1.5 X ________ = ________
Laundry Sink 1.5 X ________ = ________
Water closet [toilet] (1.6 GPF) 2.5 X ________ = ________
Bidet 1.0 X ________ = ________
Urinal (flushometer valve) Table Values* ________ = ________
Total Number of Fixture Units ________
Fixture Unit Tables for Determining Water Pipe & Meter Size Pressure Range – 46-60 PSI
Circle the length in feet to the farthest fixture & applicable service, meter & branch sizes below based on the total number of fixture
units detailed above.
Maximum Allowable Length in feet
Meter & Supply & 60’ 80’ 100’ 150’ 200’
Service Branches
¾” ¾” 20 19 17 14 11
¾” 1” 39 36 33 28 23
1” 1” 39 39 36 30 25
¾” 1¼” 39 39 39 39 39
1” 1¼” 78 76 67 52 44
1½” 1¼” 78 78 78 66 52
1” 1½”/2” 85 85 85 85 85
1½” 1½” 151 151 151 128 105
2” 1½” 151 151 151 150 117
1½” 2” 370 340 318 272 240
2” 2” 370 370 370 368 318
If count is over 370 fixtures, water demand does not meet table 610.4 and must be engineered by a registered Montana
mechanical engineers design, signed and stamped. 04.29.20
Residential (2018 IRC)
City of Bozeman Water Service Calculation Worksheet
Project Address: ___________________________________ Property Owner: ________________________________
General Contractor: _______________________________________________________________________________
Permit Number: _______________ Proposed Water Meter Size: ______________
UPC Table 610.3 Standard Design Water Supply Fixture Units
Appliances and Fixtures Fixture Units # of Fixtures Total
Bathtub or combo tub/shower (1/2” fill valve) 4.0 X ________ = ________
Bath Tub (3/4” fill valve) 10.0 X ________ = ________
Shower (per head) 2.0 X ________ = ________
Clothes washer 4.0 X ________ = ________
Dishwasher 1.5 X ________ = ________
Hose Bibb 2.5 X ________ = ________
Additional Hose Bibb (each) 1.0 X _______ = ________
Lavatory Sink 1.0 X ________ = ________
Kitchen Sink 1.5 X ________ = ________
Laundry Sink 1.5 X ________ = ________
Water closet [toilet] (1.6 GPF) 2.5 X ________ = ________
Bidet 1.0 X ________ = ________
Urinal (flushometer valve) Table Values* ________ = ________
Total Number of Fixture Units ________
Fixture Unit Tables for Determining Water Pipe & Meter Size Pressure Range – 46-60 PSI
Circle the length in feet to the farthest fixture & applicable service, meter & branch sizes below based on the total number of fixture
units detailed above.
Maximum Allowable Length in feet
Meter & Supply & 60’ 80’ 100’ 150’ 200’
Service Branches
¾” ¾” 20 19 17 14 11
¾” 1” 39 36 33 28 23
1” 1” 39 39 36 30 25
¾” 1¼” 39 39 39 39 39
1” 1¼” 78 76 67 52 44
1½” 1¼” 78 78 78 66 52
1” 1½”/2” 85 85 85 85 85
1½” 1½” 151 151 151 128 105
2” 1½” 151 151 151 150 117
1½” 2” 370 340 318 272 240
2” 2” 370 370 370 368 318
If count is over 370 fixtures, water demand does not meet table 610.4 and must be engineered by a registered Montana
mechanical engineers design, signed and stamped. 04.29.20