HomeMy WebLinkAbout16 - Design Report - Creekside Apartments - Water WATER MAIN EXTENSION
DESIGN REPORT
FOR:
CREEKSIDE APARTMENTS
BOZEMAN, MT
- 2,5
/ • �.h \
Madison Engineering
895 Technology Blvd Ste 203
Bozeman, MT 59718
(406) 586-0262
March 2016
CREEKSIDE APARTMENTS
WATER SYSTEM DESIGN REPORT
A. General
This design report will give an overview of the proposed water main extension for the
Creekside Apartments project located at North 27th Avenue and Catamount Street in
Bozeman, Gallatin County, Montana. The report includes a description of the proposed
water main and design parameters. The proposed improvements are anticipated to be
constructed the summer of 2016. 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. 2004 COB Design Standards and Specifications Guide, Addendum No. 5
b. COB Modifications to Montana Public Works Standard Specifications (MPWSS)
c. City adopted MPWSS and Adopted Addenda
d. WQB Circular No. 1
e. City of Bozeman Zoning Map
f. 2012 International Fire Code
B. Existing Water Supply
The proposed water main extension will be served by the existing City of Bozeman water
distribution system. City of Bozeman Water Department supplied the following information
regarding pressures of the existing system:
Fire Hydrants 1889 & 1890 —Catalyst St.
Static Pressure: 118 psi
Pitot Pressure: 80 psi
Residual pressure: 105 psi
Hydrant Discharge Calculation—2.5 inch port, during test
Qt= 167(p).s
Qt= 167 x 80.5
Qt= 1,494 gpm
Distribution Main Capacity—Fire flow at minimum residual pressure
Qr=Qt[(I's—Pr)/(ps—pt)]0.54
Qr= 1,494[(118—20)/(118—80)]1.14
Qr=2,492 gpm
Qt= Hydrant Discharge During Test
Qr= Fire Flow at Residual Pressure
p = Pitot Pressure
Ps= Static Pressure
Pr = Minimum Residual Pressure
Pt= Pitot Pressure
Creekside Apartments—Water Design Report
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C. Proposed Water System
The proposed water main extension will consist of a total of 1,148 linear feet of 8" Class 51
ductile iron pipe. There are two existing stubs in Catamount Street that will be connected via
386 linear feet of 8" Class Ductile Iron Pipe. An 8"x8" Tee will extend this water main
through the Creekside Apartments site approximately 762 linear feet where it will be
connected to the City of Bozeman system via an 8" stub in North 27th Ave and Catalyst St.
The layout of the proposed water main meets the City of Bozeman design criteria and will be
located within either a 60' wide or a 30' wide easement. The proposed water main will be
separated from any existing sanitary sewer main by a minimum horizontal distance of 10 feet
and a vertical distance of 18 inches. Two fire hydrants will be installed for fire suppression
as well as flushing of the main. Gate valves will be installed at property lines.
The water service lines have been sized based on fixture units and will be 2-inch copper
service lines. The fire service will be 4" ductile iron pipe.
D. Capacity Analysis
A capacity analysis was performed on the proposed water main extension. The water main
extension was designed to meet the maximum day demand plus fire flow during the peak
hour. We evaluated the proposed system based on the City of Bozeman's Design Standards
using 170 gpd per capita for the residential development.
The proposed residential development will be completed in two phases totaling 142 units
(140 two bedroom units and 2 one bedroom units). Table 1 shows the water demand for the
development being served by the water main extension based on 170 gpd per capita usage
and 2.1 1persons per dwelling unit for a total residential population of 300.
TABLE 1
WATER DEMAND—RESIDENTIAL
Density Total Daily Flow Total Flow Total Flow
Units (residents/unit) Residents Rate/resident d (gpm)
142 2.11 300 170 51,000 107
It is anticipated the average daily demand for the residential units will be 107 gpm, based on
an 8-hour day.
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 average daily 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 applied to the average daily
demand of 107 gpm.
Creekside Apartments—Water Design Report
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TABLE 2
PEAKING FACTORS
Flow Designation Peaking Factor Flow m
Average Daily Demand 1 107
Maximum Daily Demand 2.3 246
Peak Hour Demand 3 321
The required fire flow of 4,500 gpm for a Type V-B building was obtained from Table
B105.1 of the International Fire Code. A 75% flow reduction may be applied to the required
fire flow because the buildings will have a fire sprinkler 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 a 75% reduced fire flow demand of 1,125 gpm and a peak hour demand of 321
gpm, a peak hour flow of 1,446 gpm (3.22 cfs) is required. Flow analysis of an 8-inch D.I.
pipe with a C value of 130 can provide the required 1,125 gpm with a pressure drop of
approximately 14 psi from 118 psi to 104 psi, well above the minimum of 20 psi. Capacity
analysis calculations outlining the capacity of the proposed 8-inch pipe is included in the
appendix of this report.
E. Conclusion
Based on this analysis, the proposed 8-inch water main extension for the Creekside
Apartments project provides adequate service to meet the peak hour demand and fire flows of
the development. This project will require the approval of the City Engineer and MDEQ.
Appendix
Capacity Analysis
Creekside Apartments—Water Design Report
Page 3 of 3
Appendix
Creekside 8" Water Main
Project Description
Friction Method Hazen-Williams Formula
Solve For Pressure at 2
Input Data
Pressure 1 118.00 psi
Elevation 1 4658.00 ft
Elevation 2 4650.00 ft
Length 1148.00 ft
Roughness Coefficient 130.000
Diameter 0.67 ft
Discharge 3.22 ft'/s
Results
Pressure 2 103.91 psi
Headloss 40.50 ft
Energy Grade 1 4931.47 ft
Energy Grade 2 4890.98 ft
Hydraulic Grade 1 4930.18 ft
Hydraulic Grade 2 4889.68 ft
Flow Area 0.35 ftz
Wetted Perimeter 2.10 ft
Velocity 9.13 ft/s
Velocity Head 1.30 ft
Friction Slope 0.03527 ft/ft
Bentley Systems,Inc. Haestad Methods Soh W10pfitewMaster V8i(SELECTseries 1) [08.11.01.03]
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