HomeMy WebLinkAbout20 - Design Report - Billings Clinic Bozeman Campus - Water, Sewer
September 4, 2020
Project No. 15063.02
WATER AND SANITARY SEWER DESIGN REPORT
FOR
BILLINGS CLINIC BOZEMAN CAMPUS
SITE NARRATIVE
Billings Clinic Bozeman Campus is located on Lot 2A-1, Minor Subdivision 221 F in Bozeman,
Montana. The proposed campus is a 58-acre development that will be primarily medical related
facilities with complimentary commercial development. Public water and sewer mains are available
adjacent to the parcel from Davis Lane to the west and public water main is also available in the
North 27th Avenue near the southeast corner of the parcel. The public water and sewer mains are
owned and operated by the City of Bozeman. This report summarizes the calculations performed
for the water and sewer design for the site.
WATER
Water for the proposed development is provided by a new 12-inch water main from Davis Lane that
will be upsized to 16-inch water main and looped through the Billings Clinic Bozeman Campus and
out to North 27th Street where the water main currently dead ends in North 27th Avenue near the
southeast corner of the campus.
The entire 58-acre campus is currently zoned B-2 Community Business District with a land use
designation Regional Commercial and Services. Per table 3.8 of the 2017 Water facility Plan, the
average domestic flow maximum flow for Regional Commercial & Services is as follows:
o Average Domestic Flow = 815 gallons/acre/day x 58 acres = 47,270 gpd
o Maximum Hour (3:1 ratio) = 126,810 gpd
o Maximum Flow = 98 gallons per minute
It is anticipated that all the buildings within the campus will be provided with fire protection
systems. Fire demand must be based on the largest planned commercial building for the campus.
The largest planned building is the new hospital with an estimated total area of 450,000 square feet.
The hospital will be Construction Type 1A. Using Table B105.1: Minimum Required Fire-Flow and
Flow Duration for Buildings (attached) in Appendix B of the 2012 International Fire Code, the
P:15063.02_Utility_Design_Report 2 (09/04/20) PJD/bc
required fire flow is 6,000 gallons per minute. A reduction in required fire-flow of up to 75% is
allowed if a building is provided with an automatic sprinkler system, which would reduce the
required fire-flow to 1,500 gpm. To be conservative, this analysis utilizes a fire-flow of 2,000 gpm.
500 gpm was used for the automatic sprinkler system.
Based on the maximum estimated domestic flow and fire demand, the estimated design flow for the
project is as follows:
o Maximum Domestic Flow → 98 gpm
o Fire Sprinkler System Flow → 500 gpm
o Maximum Fire Flow → 2,000 gpm
o Modeled Peak design flow → 2,598 gpm
Two hydrant flow tests (attached) were completed as part of the 2017 Water Facility Plan on existing
hydrants. The first hydrant is located along Sundew Lane located approximately 2,400 feet south
from the Billings Clinic Bozeman Campus. This test resulted in a total flow of 3,002 gallons per
minute with a residual pressure of 90.2 psi. The second hydrant is located along Valley Center Road
located approximately 3,000 feet southeast from the Billings Clinic Bozeman Campus. This test
resulted in a total flow of 3,121 gallons per minute with a residual pressure of 97.7 psi.
The above data was used to create a water model in WaterCAD. The Billings Clinic Bozeman
Campus water system will be looped from the north through Davis Lane, and from the south
through both Davis Lane and North 27th Avenue. The water model was created conservatively using
two of the source locations, when there will be three sources including the loop across I-90. With
the peak design flow of 2,598 gpm, the residual pressure at the hospital was 109 psi. The highest
velocity through any of the modeled pipes was 6.76 ft/s, which was the existing 8-inch water main
heading north through Sora Way. The highest velocity through any of the new proposed pipes on
the hospital campus was 2.46 ft/s. The result tables from the water model are attached.
Therefore, adequate flow and water pressure (above 35 psi) will be available at each lot during peak
flow conditions (including under fire-flow conditions) and water main sizes meet or exceed the
required minimum diameters. Water velocities will also remain under the City of Bozeman required
maximum 15 ft/s during fire-flow conditions.
SANITARY SEWER
Sanitary sewer for the proposed campus will outfall to the proposed 27-inch sanitary sewer main
that is proposed to be installed in Davis Lane by the City of Bozeman. A 12-inch sanitary sewer
main is proposed to be installed from Davis Lane to the roundabout. An 8-inch sanitary sewer main
is proposed to be installed from the roundabout to North 27th Street.
Flows were estimated based the parcel sizes and zoning of the Billings Clinic parcel and parcels
immediately east and south of the property that could potentially be served by the sewer
infrastructure within the Billings Clinic parcel (see attached exhibit). B-2 zoning was assumed for
P:15063.02_Utility_Design_Report 3 (09/04/20) PJD/bc
the “Bus Barn Parcel” as there is potential that parcel is further developed in the future. We
assumed a peaking factor 4 for all parcels for conservatism as there is potential that this area is
developed relatively densely. Based on the attached sewer calculations potential peak sewer flows
are as follows:
• 12-inch Sanitary Sewer from Davis Lane to the Roundabout → 497
gpm
• Flows East of Roundabout on 8-inch Sanitary Sewer (excluding Zones A & B) → 317
gpm
As shown by the attached sewer pipe calculations the proposed capacity of the sanitary sewer mains
at 75% capacity are as follows:
• 12-inch Sanitary Sewer Main → 827 gpm
• 8-inch Sanitary Sewer Main → 355 gpm
As shown above the proposed sanitary sewer mains have adequate capacity to serve the Billings
Clinic campus as well as adjacent properties.
CONCLUSION
As noted above, the proposed water and sanitary sewer improvements are adequately sized for the
estimated capacity needs.
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D7D6D4D52 PARKINGBUILDINGA3BUILDINGC8BUILDINGC7PARKINGPARKING MASTER SITE PLANNORTH0250SCALE:1" = 500'500250P:\15063_02_Minor_Sub_221_Blgs_Clinic_Boz_Off-Site_Imp_PM\CADD_C3D\PRODUCTION_DWG\ON-SITE\NEW ON-SITE 051220\15063_02_MASTERPLAN.dwg, 9/4/2020 11:13:15, ANSI full bleed A (8.50 x 11.00 Inches), 1:1
ESTIMATED SEWER FLOWS FULL BUILDOUT
Area Zoning Acerage Multipler Average Flow w/o Inf (gpd)Infiltration Total Flow Total Flow (gpm)Peaking Factor Peak Flow (gpm)
BC Zone A B2 16.8 2000 33600 2520 36120 25 4 100
BC Zone B B2 15 2000 30000 2250 32250 22 4 90
BC Zone C B2 9 2000 18000 1350 19350 13 4 54
BC Zone D B2 11.3 2000 22600 1695 24295 17 4 67
Open Space Open Space 6 25 150 900 1050 1 4 3
East Lake/Catron B2 10.05 2000 20100 1507.5 21607.5 15 4 60
Bus Barn B2 17.7 2000 35400 2655 38055 26 4 106
Cattail Lake Ph 2 R4 7.9 1950 15405 1185 16590 12 4 46
Total 93.75 175255 14063 189317.5 131 4 497
ESTIMATED SEWER FLOWS EAST OF ROUNDABOUT
Area Zoning Acerage Multipler Average Flow w/o Inf (gpd)Infiltration Total Flow Total Flow (gpm)Peaking Factor Peak Flow (gpm)
BC Zone C B2 9 2000 18000 1350 19350 13 4 54
BC Zone D B2 11.3 2000 22600 1695 24295 17 4 67
Open Space Open Space 6 25 150 900 1050 1 4 3
East Lake/Catron B2 10.05 2000 20100 1507.5 21607.5 15 4 60
Bus Barn B2 17.7 2000 35400 2655 38055 26 4 106
Cattail Lake Ph 2 R4 7.9 1950 15405 1185 16590 12 4 46
Total 61.95 111655 9293 120947.5 84 4 317
Project no.15063.02
9/4/2020
Sanitary Sewer Pipe Flow
Discharge Pipe (75% full)
n 0.011 PVC Mannings Roughness Coefficient
d 12 inches Pipe Diameter
S 0.0025 ft/ft Pipe Slope
R 0.299 ft2 Hydraulic Radius (75% full)
A 0.60883 ft2 Area (75% full)
Q75 1.84378 cfs Flow Capacity (75% full)
827.544 gpm
Discharge Pipe (100% full)
n 0.011 PVC Mannings Roughness Coefficient
d 12 inches Pipe Diameter
S 0.0025 ft/ft Pipe Slope
R 0.25 ft2 Hydraulic Radius
A 0.7854 ft2 Area
Q100 2.11097 cfs Flow Capacity
V 2.69 ft/sec
Project no.15063.02
9/4/2020
Sanitary Sewer Pipe Flow
Discharge Pipe (75% full)
n 0.011 PVC Mannings Roughness Coefficient
d 8 inches Pipe Diameter
S 0.004 ft/ft Pipe Slope
R 0.19933 ft2 Hydraulic Radius (75% full)
A 0.27059 ft2 Area (75% full)
Q75 0.79103 cfs Flow Capacity (75% full)
355.038 gpm
Discharge Pipe (100% full)
n 0.011 PVC Mannings Roughness Coefficient
d 8 inches Pipe Diameter
S 0.004 ft/ft Pipe Slope
R 0.16667 ft2 Hydraulic Radius
A 0.34907 ft2 Area
Q100 0.90566 cfs Flow Capacity
V 2.59 ft/sec