HomeMy WebLinkAbout20 - Design Report - Town & Country - Water WATER MAIN EXTENSION
DESIGN REPORT
FOR:
TOWN & COUNTRY
BOZEMAN, MT
Prepared By:
MADISON
ENGINEERING
Madison Engineering
895 Technology Drive, Suite 203
Bozeman, MT 59718
(406) 586-0262
March 2020
WATER MAIN EXTENSION
DESIGN REPORT
FOR:
TOWN & COUNTRY
BOZENIAN, MT
! •il
Madison Engineering
895 Technology Blvd Ste 203
Bozeman, MT 59718
(406) 586-0262
March 2020
TOWN AND COUNTRY
WATER SYSTEM DESIGN REPORT
A. General
This design report will give an overview of the proposed water main extension for the development
of Town and Country Food Store infrastructure improvements. Improvements are anticipated to
be constructed during the Summer of 2020. Once the water main is constructed and approved, the
main will become a part of the City of Bozeman system.
The following references were used in the preparation of this report:
a. COB Design Standards and Specifications Policy, 2017. Addendum #6
b. COB Modifications to Montana Public Works Standard Specifications (MPWSS).
c. WQB Circular No. 1
d. City of Bozeman Zoning Map
e. City of Bozeman Water Facility Plan
f. 2015 International Fire Code
Existing System
The proposed water main extension will be served by the existing City of Bozeman water
distribution system, which will be tied into the existing 12" water main in Fallon Street and
connecting to the existing 8" main located on site. The following information was obtained by the
City of Bozeman on August 10, 2019.
Fire Hydrants: 2683 and 2684
Static Pressure: 120 psi
Pitot Pressure: 90 psi
Residual pressure: 108 psi
Hydrant discharge: 1,590 gpm from 2.5" port
Distribution Main Capacity —Fire flow at minimum residual pressure
Qr= Qt[(Ps—p.�(Ps-Pt)]0.54
Qr= 1,590 [(120—20)/(120—90)]0.54
Qr = 3,046 gpm
Qt= Hydrant Discharge during Test
Qr= Fire Flow at Residual Pressure
P,= Static Pressure
Pm = Minimum Residual Pressure= 20 psi
Pr= Residual Pressure
Pt= Pitot Pressure
Town and Country
Water Design Report
Page 1 of 3
B. Proposed Water System
The proposed water main extension consists of approximately 224 linear feet of new 8" ductile
iron pipe extending south along the proposed parking driveway. The new main will connect to the
existing 12" water main in Fallon Street and to the existing 8" main located within the site.
The layout of the proposed water main meets the COB design criteria and will be located within a
30' wide easement and separated from the existing sanitary sewer main by a minimum distance of
10 feet horizontally.New gate valves will be installed at the connection point to the existing mains,
per City standards and also meeting spacing requirements. An existing fire hydrant will be
relocated to accommodate the new 8" ductile iron main.
C. Capacity Analysis
The Town and Country water main extension is proposed for the development of Town& Country,
which includes 4.15 acres of B-2 (community business district to provide for a broad range of
mutually supportive retail and service functions) zoning. The City of Bozeman design standards
and specification policy's Table V-1 suggests using 2000 gallons/acre/day for wastewater flows
from a B-2, community business district. Applying this value to a 4.15-acre parcel:
2000 gallons
4.15 acres * acre = 8,300 gpd
day
Based on these parameters, the 4.15-acre development, at full build out, will have an estimated
water usage of 8,300 gal/day, or an average daily demand of 17 gpm, based on an 8-hour day. The
main will be looped into the existing City of Bozeman system and served from both ends, however
calculations were based on a dead-end line to be conservative. The calculation below shows the
water main extension has been designed to meet the maximum day demand plus fire flow during
the peak hour.
In addition to the average daily demand, the water main extension must account for peak periods
of daily use. Peaking factors are applied to the demand and account for these peak periods in daily
use. The peaking factors used are maximum daily use and peak hour and are obtained from the
City of Bozeman Design Standards. Table 2 shows the peaking factors and the resultant flows
from those factors when applied to the average daily demand of 17 gpm.
TABLE 1
PEARING FACTORS
Flow Designation Peaking Factor Flow (gpm)
Average Day Demand 1 17
Maximum Day Demand 2.3 39.1
Maximum Hour Demand 3 51
Town and Country
Water Design Report
Page 2 of 3
Based on communication with the architect, the maximum square footage of the future building
pad is estimated at 5,880 sf. The future building will be a 2-hour V-B type construction with fire
sprinklers. A Type V-B 5,880 sf building requires 2,000 gpm per the 2015 International Fire Code,
Table B105.1(2). The 2,000 gpm fire flow can be reduced to a minimum requirement of 1,500
gpm because of the sprinkling system.
A Hazen-Williams"C"Factor of 130 was used in the pipe evaluation. The working residual water
pressure shall not be less than 20 psi at any point in the water distribution system under maximum
day plus fire flow. The velocity shall not exceed 15 feet per second through the main line.
Results
Based on the analysis outlined previously, the required fire flow is 1,500 gpm and with the
maximum hour demand of 51 gpm, a maximum hour flow of 1,551 gpm is required. Flow analysis
shows that an 8-inch DI pipe with a C value of 130 can provide 1,551 gpm with a pressure drop of
5.65 psi from 100 psi to 94.35 psi, above the minimum of 20 psi. The pipe velocity is 9.90 ft/s.
This is a conservative analysis based on a dead-end line, however this line will be looped into the
existing main and served from both ends.
A Conclusion
Based on this analysis, the proposed 8-inch water main extension for the development of the Town
and Country Food Store provides adequate service to meet the peak hour demand and fire flows
for the grocery store. The water main design is consistent with the City of Bozeman Water Facility
Plan.
This project will require the approval of the City Engineer and MDEQ.
Town and Country
Water Design Report
Page 3 of 3
Town & Country Water Capacity
Project Description
Friction Method Hazen-Williams Formula
Solve For Pressure at 2
Input Data
Pressure 1 100.00 psi
Elevation 1 4815.90 ft
Elevation 2 4819.70 ft
Length 224.00 ft
Roughness Coefficient 130.000
Diameter 8.00 in
Discharge 1551.00 gal/min
Results
Pressure 2 94.35 psi
Headloss 9.23 ft
Energy Grade 1 5048.08 ft
Energy Grade 2 5038.85 ft
Hydraulic Grade 1 5046.56 ft
Hydraulic Grade 2 5037.33 ft
Flow Area 0.35 ft2
Wetted Perimeter 2.09 ft
Velocity 9.90 ft/s
Velocity Head 1.52 ft
Friction Slope 0.04119 ft/ft
Bentley Systems,Inc. Haestad Methods SoIBlfafl&'yeF vmaster V81(SELECTseries 1) [08.11.01.03]
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