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HomeMy WebLinkAbout20 - Design Report - Palisades Condominiums - Water, Sewer WATER & SEWER DESIGN REPORT FOR: PALISADES CONDOMIUM INFRASTRUCTURE IMPROVEMENTS BOZEMAN, MT Prepared By: M MADISON ENGINEERING Madison Engineering 895 Technology Drive, Suite 203 Bozeman, MT 59718 (406) 586-0262 AUGUST 2020 WATER MAIN DESIGN REPORT FOR: PALISADES CONDOMINIUM INFRASTRUCTURE IN PROVEMENTS BOZEMAN, MT Madison Engineering 895 Technology Blvd Ste 203 Bozeman, MT 59718 (406) 586-0262 NTA�*,q AUGUST 2020 =• CI-IRIS G. '• • nn nn ccVV P E uj a r �'. /CENS�?- '�"t i, PALISADES CONDOMIUM INFRASTRUCTURE IMPROVEMENTS WATER SYSTEM DESIGN REPORT A. General Project Description This design report will give an overview of the proposed water main extension for the development of Palisades Condominium Infrastructure Improvements. The proposed improvements are anticipated to be constructed during the fall 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 looped. The two connection locations are located within Catamount Street existing 12" water main and the existing 8" water main within the current development. The following information was obtained from the City of Bozeman: Hydrant ID#: 1891 Maximum Day Demand Minimum Pressure: 20.20 psi Maximum Day Demand Average Pressure: 90.92 psi Maximum Day Demand Maximum Pressure: 130.51 psi Maximum Day Demand Available Fire Flow at 20 psi: 12,400 gpm Hydrant ID#: 2478 Maximum Day Demand Minimum Pressure: 20.92 psi Maximum Day Demand Average Pressure: 89.97 psi Maximum Day Demand Maximum Pressure: 131.36 psi Maximum Day Demand Available Fire Flow at 20 psi: 7,000 gpm The two hydrants listed above were used to model the existing connections to the City system. A three-point pump curve was used to model the existing system. The first point uses the static pressure of the system when the flow is equal to zero. The second point uses the maximum day demand available fire flow at 20 psi (given above). The third point was determined by selecting an arbitrary pressure (90 psi) between the static pressure and the minimum pressure of 20 psi. An example calculation for Hydrant ID #2478 is given below: Palisades Condominium Infrastructure Improvements Water Design Report Page ] of 3 Qr= Qt[(Ps—Pm)/(Ps—Pr)]0.54 Qr= 7,000 [(131.36— 90)/(131.36—20.92)]0.54 Qr = 4,120 gpm at 90 psi Qt= Maximum Day Demand Available Fire Flow @ 20 psi Qr= Fire Flow at Desired Fire Flow Residual Pressure Ps= Static Pressure Pm = Desired Residual Pressure= 55 psi Pr= Minimum Residual Pressure=20 psi B. Proposed Water System The proposed water main extension for Palisades Condominium consists of approximately 353 linear feet of 8" ductile iron pipe that will connect to the existing water mains via tapping tee. The layout of the proposed water main meets the COB design criteria and will be located within a 30' foot wide public utility easement and separated from the proposed sanitary sewer main by a minimum of 10 feet horizontally. Fire hydrants will be installed per COB design criteria and will not exceed the recommended distance. C. Capacity Analysis The Palisades Condominium water main extension is proposed for the multiphase development of 6 buildings. The proposed project consists of a comprised total of 19-units(19—2 Bedroom Units), which sits on a 1.57 acre R-3 (Medium Density Residential)zoned land.An estimation of the water flow rate was based on the City of Bozeman's design standards and specification policy, which suggests using an average daily flow rate of 2.11 people per dwelling unit and 170-gallons per capita per day. Applied to the units in each phase the required water flow rate is calculated: Phase I—Full Build out ( residents gallons 19 units * 2.11 * 170 day) = 6,816gpd unit capita Based on these parameters, the phased development will have an estimated water usage of 6,816 gpd (4.73 gpm) at full build out. 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 1 shows the peaking factors and the resultant flows from those factors when applied to the average daily demand. Palisades Condominium Infrastructure Improvements Water Design Report Page 2 of 3 TABLE 1 PEAKING FACTORS Flow Designation Peaking Factor Flow m Average Day Demand 1 4.73 Maximum Day Demand 2.3 10.88 Maximum Hour Demand 3 14.19 Three types of buildings will be constructed and will consist of 1 —2 Plex and 3 —3 Plexes and 2 —4 Plexes for a total of 6 individual buildings. The square footage for each type of building are as follows: 2 Plex=4,010 sf, 3 Plex= 6,081 sf, 4 Plex= 8,122 sf. Based off communication with th architect,the units are expected to be type V-B construction with fire sprinklers. A Type V-B 8,122 sf building requires 1,500 gpm for a 2-hour flow duration per the 2015 International Fire Code, Table B 105.1(2). Results Based on the analysis outlined above, the required minimum fire flow is 1,500 gpm and the maximum hour demand is 14.19 gpm. The maximum hour demand was distributed throughout each water service within the subdivision. The attached WaterCAD analysis was designed to incorporate the maximum hour demand throughout the system.A fire flow analysis was performed at each node throughout the system where a building has a potential fire flow demand in addition to all hydrants. The flow analysis shows that an 8-inch DI pipe can provide the development with the required flow of 1,500 gpm in addition to the max. hour demand and remain above the minimum pressure of 20 psi. The maximum velocity within the water mains was constrained to 15 ft. per second per City of Bozeman specifications. See attached flow analysis for calculations. D. Conclusion Based on this analysis,the proposed 8-inch ductile iron water main extension serving the Palisade Condominiums residential development provides adequate service to meet the 19-unit peak hour demand and fire flow requirements for the development. The water main design is consistent with the City of Bozeman Water Facility Plan. This project will require the approval of the City of Bozeman Engineer and MDEQ. 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