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HomeMy WebLinkAboutWaterDesignReport_08-23-21 WATER MAIN DESIGN REPORT FOR: Bozeman CoHousing INFRASTRUCTURE IMPROVEMENTS BOZEMAN, MT Prepared By: Madison Engineering 895 Technology Drive, Suite 203 Bozeman, MT 59718 (406) 586-0262 AUGUST 2021 Bozeman CoHousing Infrastructure Improvements Water Design Report Page 1 of 3 BOZEMAN COHOUSING INFRASTRUCTURE IMPROVEMENTS WATER SYSTEM DESIGN REPORT A. General This design report will give an overview of the proposed water main extension for the development of the Bozeman CoHousing project. The proposed improvements are anticipated to be constructed during the fall of 2021. No phasing is proposed for the water system; however the units within the development will be phased. 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. The proposed main will connect to the existing 8” DI main in Wagonwheel Rd. The proposed main branches to the north and east near STA 3+00 and will dead-end at the north property line with a blow-off assembly. The east branch of the water main will terminate at a fire hydrant. This will allow for future extension of the water main to the north and also permit for a looped connection once the future main is constructed. The following information was obtained from the City of Bozeman: Hydrant ID#: 593 Static Pressure: 60 psi Residual Pressure: 58 psi Hydrant ID#: 589 Pitot Pressure: 44 psi Hydrant Flow (2.5” Nozzle): 1110 gpm The two hydrants listed above were used to create a three-point pump curve to model the existing connection to the City 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 (55 psi) between the static pressure and the minimum pressure of 20 psi. An example calculation for Hydrant ID #593 is given below: Bozeman CoHousing Infrastructure Improvements Water Design Report Page 2 of 3 Qr = Qt[(Ps – Pm)/(Ps – Pr)]0.54 Qr = 1,110 [(60 – 25)/(60 – 20)]0.54 Qr = 1,033 gpm at 25 psi Qt = Maximum Day Demand Available Fire Flow @ 20 psi Qr = Fire Flow at Desired Fire Flow Residual Pressure Ps = Stat ic Pressure Pm = Desired Residual Pressure = 55 psi Pr = Minimum Residual Pressure = 20 psi B. Proposed Water System The proposed water main extension for Bozeman CoHousing consists of approximately 678 linear feet of 8” ductile iron pipe. 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. The fire hydrant will be installed per COB design criteria and will not exceed the recommended spacing. C. Capacity Analysis The proposed multi-phase project consists of a total of 43 residential units along with a common house (10 - 4 Plexes and 3 ADU’s), which sits on a 5.31-acre R-3 (Residential Medium Density District) 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 total number of units in the development the required water flow rate is calculated: Full Build Out: ൬43 units ∗ 2.11 residents unit ∗ 170 gallons capita day ൰ = 15,424 gpd Based on these parameters, the phased development will have an estimated water usage of 15,424 gpd (10.71 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. Bozeman CoHousing Infrastructure Improvements Water Design Report Page 3 of 3 TABLE 1 PEAKING FACTORS Flow Designation Peaking Factor Flow (gpm) Average Day Demand 1 10.7 Maximum Day Demand 2.3 24.6 Maximum Hour Demand 3 32.1 The proposed buildings to be constructed include 4 plexes along with three (3) ADU’s above garages in addition to a common house. The building square footage ranges from 3,398 sf to 4,866 sf for the 4-plexes. The common house (includes one 4 plex) is 15,431 sf. The units are expected to be type V-B construction without fire sprinklers. The only building that will require fire sprinklers is the common house with the attached 4 plex. A Type V-B 15,431 sf building with an automatic sprinkler system requires 1,500 gpm for a 3-hour flow duration per the 2015 International Fire Code, Table B105.1(2). A Type V-B 4,866 sf building without an automatic sprinkler system requires 2,000 gpm for a 2-hour flow duration. Results Based on the analysis outlined above, the required minimum fire flow is 2,000 gpm and the maximum hour demand is 32.1 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 (including the base peak hour demand) where a building has a potential fire flow demand. The flow analysis shows that an 8-inch DI pipe can provide the development with the required flow of 2,000 gpm in addition to the max. day demand and remain above the minimum pressure of 20 psi. See attached flow analysis for calculations. D. Conclusion Based on this analysis, the proposed 8-inch ductile iron water main serving the CoHousing residential development provides adequate service to meet the 43-unit peak hour demand and fire flows 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. Base Fire Flow Report Base Fire Flow gpm2,000Fire Flow (Needed)NoneFire Flow Auxiliary Results Type gpm3,500Fire Flow (Upper Limit) ft/s15.00Velocity (Upper Limit) psi20Pressure (Residual Lower Limit)psi(N/A)Pressure (System Lower Limit) psi20Pressure (Zone Lower Limit) ft/s0.00Pipe Velocity Greater Than FalseUse Minimum System Pressure Constraint? psi0Node Pressure Less Than TrueUse Velocity Constraint? All PipesPipe Set FalseUse Pipe Velocity Greater Than? Fire FlowFire Flow Nodes FalseUse Node Pressure Less Than?NoneFire Flow Auxiliary Results Type Adding to Baseline Demand Apply Fire Flows By <No Elements>Auxiliary Output Selection Set 13: Base Fire Flow, Junction and Hydrant Alternative Report Fire Flow (Upper Limit)(gpm) Fire Flow (Needed)(gpm) Velocity (Upper Limit)(ft/s) Specify Local Fire Flow Constraints? LabelID* 3,5002,00015.00FalseJ-232True 3,5002,00015.00FalseJ-638True Pressure (System Lower Limit) (psi) Pressure (Zone Lower Limit) (psi) Pressure (Residual Lower Limit) (psi) (N/A)2020 (N/A)2020 Page 1 of 127 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 8/16/2021 WaterCAD CONNECT Edition Update 2 [10.02.00.43] Bentley Systems, Inc. Haestad Methods Solution CenterCoHousing WaterCad.wtg Fire Flow Node FlexTable: Fire Flow Report Junction w/ Minimum Pressure (Zone) Pressure (Calculated Residual) (psi) Fire Flow (Available) (gpm) Fire Flow (Needed) (gpm) Label J-26233,5002,000J-2 J-20203,3092,000J-6 Page 1 of 127 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 8/16/2021 WaterCAD CONNECT Edition Update 2 [10.02.00.43] Bentley Systems, Inc. Haestad Methods Solution CenterCoHousing WaterCad.wtg Scenario: Automated Fire Flow Analysis P-1 4P-13 P-12 P-11 P-4 P-2 Page 1 of 127 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 8/3/2021 WaterCAD CONNECT Edition Update 2 [10.02.00.43] Bentley Systems, Inc. Haestad Methods Solution CenterCoHousing WaterCad.wtg CITY OF BOZEMAN Fire Flow Request Form PHONE (406) 582-3200 FAX (406) 582-3201 The results of the fire flow information that you requested are as follows: Wagon Wheel Rd. Bozeman Co- Housing Hydrant #593 Static- 60psi Residual- 58psi Hydrant #589 Pitot- 44psi Flowing 1110 GPM on a 2.5” nozzle. The test was performed on 6/7/2021. If you have questions or need further information feel free to email. Data Disclaimer: Water distribution information is calculated using hydraulic modeling software and is subject to variation. Actual field conditions may vary. This information provided to the requestor for evaluation purposes only, without warranty of any kind, including, but not limited to any expressed or implied warranty arising by contract, stature, or law. In no event regardless of cause, shall the City be liable for any direct, indirect, special, punitive or consequential damages of any kind whether such damages arise under contract, tort, strict liability or inequity.