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HomeMy WebLinkAboutWater Design Report 01-13-2020 INTRODUCTION The proposed Mountain Vista Housing Complex is a 25-unit development consisting of Duplex and Single Units, located on the property described in Doc. No. 2046120 in the Southwest Quarter, Section 11, Township 2 South, Range 5 East of P.M.M.. The project will require connection to the existing City of Bozeman water and sanitary sewer systems. WATER SYSTEM LAYOUT The Mountain Vista Housing complex will require tapping in to an existing 10” ductile iron water main in West Babcock Street with 8” Class 51 ductile iron pipe. All new water mains are to be installed in the City standard location and will be located 10’ away from any proposed sewer mains. The 8” main extending into the property will have 4 stubs with blowoff valves. A WaterCAD analysis is enclosed at the end of the report analyzing the 8-inch water main to be installed with this project. The connection to the existing system was modeled as a pump curve using data obtained from the City of Bozeman Water Department: static, residual and pitot pressures were read at hydrant #968, located on Donna Avenue, south of Babcock Street. This data was used to develop the pump curve used at the connection point to model the existing system. The following equation based off of the Hazen Williams method is used to generate the pump curve: Q = Qf x ((Ps - P) / (Ps - Pr))0.54 Where: Q = flow predicted at desired residual pressure, Qf = total flow measured during test, Pr= residual pressure during test, Ps = static pressure and P = residual pressure at the desired flow rate. In the model, the pump is connected to a reservoir which acts as a source of water. The elevation of the reservoir is fixed at the elevation of the pump, which is also equivalent to the elevation of the tie-in point. The reservoir does not create any head on the system; the head is generated entirely by the pumps. The input data and the pump curves are included at the end of the report. The pump curve table includes all calculations and equations used in determining flow characteristics at the connection point. A C-factor of 130 was chosen for ductile iron class 51 pipe. WATER DISTRIBUTION SYSTEM SIZING Residential Units: Average Daily Residential Usage = 170 gallons per capita per day Average Population Density = 2.11 persons/dwelling unit Minimum Fire Hydrant Flow = 1,500 gpm Residual Pressure Required = 20 psi for Fire Flow Average Day Demand (Peaking Factor = 1) Maximum Day Demand (Peaking Factor = 2.3) Maximum Hour Demand (Peaking Factor = 3.0) Residential Water Demands (Demand Junction 1) Average Day Demand = 10 d.u. x 2.11 persons/d.u. x 170 gpcpd = 3,587 gpd = 2.6 gpm Maximum Day Demand = 2.6 gpm x 2.3 = 5.9 gpm Peak Hour Demand = 2.6 gpm x 3.0 = 7.8 gpm Residential Water Demands (Demand Junction 2) Average Day Demand = 15 d.u. x 2.11 persons/d.u. x 170 gpcpd = 5,380 gpd = 3.8 gpm Maximum Day Demand = 3.8 gpm x 2.3 = 8.8 gpm Peak Hour Demand = 3.8 gpm x 3.0 = 11.5 gpm Available Pressure: 10-inch class 51 ductile iron main Babcock Street Static = 114 psi (Hydrant #986) Residual = 88 psi (Hydrant #986) Pitot (2.5” nozzle) = 108 (Hydrant #986) Flowing = 1,575 gpm (Hydrant #1985) HYDRAULIC ANALYSIS Design Report - Page 4 of 6 A water distribution model was created using WaterCAD Version 10.01.00.72 for demand forecasting and describing domestic and fire protection requirements. In order to model the system, each junction node of the water distribution system was assessed a demand based on its service area. The table shown below quantifies the demands placed at the junction nodes and calculates the demands for Average Day, Maximum Day and Peak Hour within the subdivision. The peaking factor for each case is 1, 2.3 and 3.0 respectively. Mountain Vista Housing Complex (Table 1): DEMAND JUNCTION NODE DWELLING UNITS (D.U.) POPULATION (RES.) 2.17 PEOPLE PER D.U. AVERAGE DAY GPM (170 GALLONS PER DAY PER PERSON) MAX. DAY GPM PEAK HOUR GPM DJ 1 10 22 2.6 5.9 7.7 DJ 2 15 33 3.8 8.8 11.5 Total 25 54 6.40 14.73 19.21 *See Demand Junction Map for more information on which lots contribute to each Demand Junction. CONCLUSION The proposed 8-inch DIP water mains provide adequate capacity to serve the development under the Peak Hour Demand condition. The flows and pressures within the system for the Peak Hour Demands were generated with the WaterCAD program and can be found in Appendix A. The capacity of the system to meet fire flow requirements was tested by running a steady state fire flow analysis for the junction where the hydrant is located. The model shows that all hydrant junctions satisfy fire flow constraints (residual pressure > 20 psi, flow rate > 1500 gpm), while providing service to lots at peak hour. The results of the analysis at peak hourly flow are given in Appendix A. Design Report - Page 5 of 6 APPENDIX A WATERCAD MODEL Scenario Summary Report Scenario: Base Scenario Summary 1ID BaseLabel Notes Base Active TopologyActive Topology Base PhysicalPhysical Base DemandDemand Base Initial SettingsInitial Settings Base OperationalOperational Base AgeAge Base ConstituentConstituent Base TraceTrace Base Fire FlowFire Flow Base Energy CostEnergy Cost Base TransientTransient Base Pressure Dependent DemandPressure Dependent Demand Base Failure HistoryFailure History Base SCADASCADA Base User Data ExtensionsUser Data Extensions Base Calculation OptionsSteady State/EPS Solver Calculation Options Base Calculation OptionsTransient Solver Calculation Options Hydraulic Summary Steady StateTime Analysis Type TrueUse simple controls during steady state? Hazen-WilliamsFriction Method FalseIs EPS Snapshot? 0.001Accuracy 12:00:00 AMStart Time 40Trials Fire FlowCalculation Type Page 1 of 127 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 12/30/2019 WaterCAD CONNECT Edition Update 1 [10.01.00.72] Bentley Systems, Inc. Haestad Methods Solution Center180334 WaterCAD Model.wtg FlexTable: Junction Table Pressure (psi) Hydraulic Grade (ft) Demand (gpm) Demand CollectionElevation (ft) Label 1145,086.568<Collection: 1 items>4,822.50DJ-1 1135,086.5612<Collection: 1 items>4,826.10DJ-2 1135,086.560<Collection: 0 items>4,826.30HYD #1 1145,086.570<Collection: 0 items>4,822.00J-1 1145,086.570<Collection: 0 items>4,822.00J-2 1145,086.560<Collection: 0 items>4,823.40J-3 1145,086.560<Collection: 0 items>4,823.40J-4 1135,086.560<Collection: 0 items>4,826.40J-5 1135,086.560<Collection: 0 items>4,826.30J-6 1135,086.560<Collection: 0 items>4,826.30J-7 Page 1 of 127 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 12/30/2019 WaterCAD CONNECT Edition Update 1 [10.01.00.72] Bentley Systems, Inc. Haestad Methods Solution Center180334 WaterCAD Model.wtg FlexTable: Pipe Table Headloss Gradient (ft/ft) Hydraulic Grade (Stop) (ft) Hydraulic Grade (Start) (ft) Velocity (ft/s) Flow (gpm) Minor Loss Coefficient (Unified) Hazen-Williams C MaterialDiameter (in) Length (User Defined) (ft) Label 0.0004,823.504,823.500.00190.000150.0PVC999.01P-51 0.0005,086.565,086.570.12190.500130.0Ductile Iron8.0157P-3 0.0005,086.565,086.560.07120.390130.0Ductile Iron8.0173P-7 0.0005,086.575,086.570.12190.390130.0Ductile Iron8.0261P1 0.0005,086.575,086.570.08190.390130.0Ductile Iron10.0305P-2 0.0005,086.565,086.560.0001.280130.0Ductile Iron8.0132P-4 0.0005,086.565,086.560.0000.000130.0Ductile Iron8.098P-5 0.0005,086.565,086.560.0000.350130.0Ductile Iron8.043P-8 0.0005,086.565,086.560.0000.000130.0Ductile Iron8.045P-9 0.0005,086.565,086.560.0000.000130.0Ductile Iron6.011P-10 0.0005,086.565,086.560.0001.280130.0Ductile Iron8.0137P-6 Page 1 of 127 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 12/30/2019 WaterCAD CONNECT Edition Update 1 [10.01.00.72]Bentley Systems, Inc. Haestad Methods Solution Center180334 WaterCAD Model.wtg Pump Definition Detailed Report: HYD 968 Element Details 168ID Notes HYD 968Label Pump Curve Head(ft)Flow(gpm) 263.080 251.541,427 240.002,075 228.462,583 216.923,017 205.383,404 193.853,756 182.314,082 170.774,387 159.234,675 147.694,949 136.155,210 124.625,461 113.085,702 101.545,935 90.006,160 78.466,379 66.926,591 55.386,798 43.856,999 32.317,196 20.777,388 9.237,575 Pump Efficiency Type Best Efficiency Point Pump Efficiency Type %100.0Motor Efficiency %100.0BEP Efficiency FalseIs Variable Speed Drive? gpm0BEP Flow Transient (Physical) lb·ft²0.000Inertia (Pump and Motor)SI=25, US=1280Specific Speed rpm0Speed (Full)TrueReverse Spin Allowed? Page 1 of 227 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 12/30/2019 WaterCAD CONNECT Edition Update 1 [10.01.00.72] Bentley Systems, Inc. Haestad Methods Solution Center180334 WaterCAD Model.wtg Pump Definition Detailed Report: HYD 968 Page 2 of 227 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 12/30/2019 WaterCAD CONNECT Edition Update 1 [10.01.00.72] Bentley Systems, Inc. Haestad Methods Solution Center180334 WaterCAD Model.wtg Fire Flow Node FlexTable: Fire Flow Report Junction w/ Minimum Pressure (System) Pressure (Calculated Zone Lower Limit) (psi) Pressure (Zone Lower Limit) (psi) Pressure (Calculated Residual) (psi) Pressure (Residual Lower Limit) (psi) Flow (Total Available) (gpm) Flow (Total Needed) (gpm) Fire Flow (Available) (gpm) Fire Flow (Needed) (gpm) Label J-723020203,4371,5003,4371,500HYD #1 Page 1 of 127 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 12/30/2019 WaterCAD CONNECT Edition Update 1 [10.01.00.72]Bentley Systems, Inc. Haestad Methods Solution Center180334 WaterCAD Model.wtg Design Report - Page 6 of 6 APPENDIX B DEMAND JUNCTION MAP