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HomeMy WebLinkAboutWater & Sewer Design Report Design Report - Page 2 of 7 INTRODUCTION The proposed Westside Flats project is a residential multi-family development located on Lot R-2 of the J&D Family Subdivision Phase 2. The proposed project will include the extensions of May Fly Street and Dragon Fly Street east into the project to tie into a proposed center drive aisle running north-south. Nine buildings are proposed for construction along the center drive aisle to create (132) 2-bedroom apartments in a series of 12-plex and 18-plex buildings. Water and Sewer Main extensions are required to serve the property. WATER SYSTEM LAYOUT The Westside Flats Master Site Plan will connect to two existing 8” ductile iron water main stubs in Dragon Fly Street and May Fly Street on the west side of the property. A third connection will be made via tapping tee to the 8” ductile iron water main in Fallon Street at the south end of the site. An 8” water main will run north-south in the main drive aisle to connect to the proposed dwelling units. The entire water main will be installed with Phase 1 of the master site plan, and a 20’ all weather drive access will be provided for maintenance and access to the water main. Three interior fire hydrants are proposed to provide fire flow throughout the development. The water main extensions lie in a proposed 30-foot public access and utility easement. A WaterCAD analysis is enclosed at the end of the report analyzing the 8-inch water main to be installed with this project. The north connection point to the existing system was conservatively modeled as a pump curve using data obtained from the City of Bozeman Engineering Department: with pressure vs. flow data from Hydrants #2404, #2406, and #2408, located in Water Lily Drive and Fallon Street. This data was used to develop the pump curve used at the north connection point to model the existing system. 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 Design Report - Page 3 of 7 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 = 2.17 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 = 12 d.u. x 2.17 persons/d.u. x 170 gpcpd = 4,427 gpd = 3.07 gpm Maximum Day Demand = 3.07 gpm x 2.3 = 7.1 gpm Peak Hour Demand = 3.07 gpm x 3.0 = 9.3 gpm Residential Water Demands (Demand Junction 2) Average Day Demand = 18 d.u. x 2.17 persons/d.u. x 170 gpcpd = 6,640 gpd = 4.61 gpm Maximum Day Demand = 4.61 gpm x 2.3 = 10.6 gpm Peak Hour Demand = 4.61 gpm x 3.0 = 13.8 gpm Residential Water Demands (Demand Junction 3) Average Day Demand = 18 d.u. x 2.17 persons/d.u. x 170 gpcpd = 6,640 gpd = 4.61 gpm Maximum Day Demand = 4.61 gpm x 2.3 = 10.6 gpm Peak Hour Demand = 4.61 gpm x 3.0 = 13.8 gpm Residential Water Demands (Demand Junction 4) Average Day Demand = 12 d.u. x 2.17 persons/d.u. x 170 gpcpd = 4,427 gpd = 3.07 gpm Design Report - Page 4 of 7 Maximum Day Demand = 3.07 gpm x 2.3 = 7.1 gpm Peak Hour Demand = 3.07 gpm x 3.0 = 9.3 gpm Residential Water Demands (Demand Junction 5) Average Day Demand = 12 d.u. x 2.17 persons/d.u. x 170 gpcpd = 4,427 gpd = 3.07 gpm Maximum Day Demand = 3.07 gpm x 2.3 = 7.1 gpm Peak Hour Demand = 3.07 gpm x 3.0 = 9.3 gpm Residential Water Demands (Demand Junction 6) Average Day Demand = 18 d.u. x 2.17 persons/d.u. x 170 gpcpd = 6,640 gpd = 4.61 gpm Maximum Day Demand = 4.61 gpm x 2.3 = 10.6 gpm Peak Hour Demand = 4.61 gpm x 3.0 = 13.8 gpm Residential Water Demands (Demand Junction 7) Average Day Demand = 12 d.u. x 2.17 persons/d.u. x 170 gpcpd = 4,427 gpd = 3.07 gpm Maximum Day Demand = 3.07 gpm x 2.3 = 7.1 gpm Peak Hour Demand = 3.07 gpm x 3.0 = 9.3 gpm Residential Water Demands (Demand Junction 8) Average Day Demand = 12 d.u. x 2.17 persons/d.u. x 170 gpcpd = 4,427 gpd = 3.07 gpm Maximum Day Demand = 3.07 gpm x 2.3 = 7.1 gpm Peak Hour Demand = 3.07 gpm x 3.0 = 9.3 gpm Residential Water Demands (Demand Junction 9) Average Day Demand = 18 d.u. x 2.17 persons/d.u. x 170 gpcpd = 6,640 gpd = 4.61 gpm Maximum Day Demand = 4.61 gpm x 2.3 = 10.6 gpm Peak Hour Demand = 4.61 gpm x 3.0 = 13.8 gpm Design Report - Page 5 of 7 HYDRAULIC ANALYSIS A water distribution model was created using WaterCAD Version 10.03.00.69 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 project. The peaking factor for each case is 1, 2.3 and 3.0 respectively. Fire Flow estimates for the individual fire service were provided by design engineer based on the NFPA-13R. These requirements were estimated to be 60 gallons per minute (gpm) at 60 psi at the bottom of the fire riser. This fire flow and minimum residual pressure was applied to all of the junctions including the demand junctions for each building. Westside Flats Master Site Plan (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 12 26 3.07 7.1 9.2 DJ 2 18 39 4.61 10.6 13.8 DJ 3 18 39 4.61 10.6 13.8 DJ 4 12 26 3.07 7.1 9.2 DJ 5 12 26 3.07 7.1 9.2 DJ 6 18 39 4.61 10.6 13.8 DJ 7 12 26 3.07 7.1 9.2 DJ 8 12 26 3.07 7.1 9.2 DJ 9 18 39 4.61 10.6 13.8 Total 132 286 33.82 77.78 101.45 *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 Design Report - Page 6 of 7 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 units at peak hour. The results of the analysis at peak hourly flow are given in Appendix A. SANITARY SEWER SYSTEM LAYOUT The Westside Flats Master Site Plan will tie-in to the existing 8” PVC sewer main stub in Dragon Fly Street on the west side of the property approximately 210 feet south of the centerline of Babcock Street. The sanitary sewer main will run east and then south from the connection point to provide service to the 9 buildings proposed on the site. The sanitary sewer main will be installed with Phase 1 of the master site plan, and a 20’ all weather drive access will be provided for maintenance and access to the sewer main and manholes. SANITARY SEWER DEMAND The proposed site development has a total of 132 dwelling units on 8.78 acres. The proposed sewer demand was calculated assuming 2.17 persons per dwelling unit and 150 gallons per acre per day of groundwater infiltration into the system. A daily residential flow rate of 65 gallons per day per capita was used as the generation rate per the City of Bozeman 2015 Wastewater Collection Facilities Plan Update. The Harmon Formula was used to calculate the peaking factor. The following peak flow calculations were performed per City of Bozeman Design Standards: A breakdown the sanitary sewer estimates can be found in Appendix C. Equivalent Population: (2.17 people/dwelling unit) (132 dwelling units) = 286 people Assumed infiltration rate: (150 gal/acre/day) (8.78 acres) =1,317 GPD Harmon Formula: Peaking Factor = (18 + P0.5)/(4 + P0.5) where: P = Population in thousands Design Report - Page 7 of 7 Peaking Factor = (18 + 0.2860.5)/(4 + 0.2860.5) Peaking Factor = 4.09 Peak Flow Rate: (65 GPCD) (286 people) (4.09) + 1,317 GPD = 77,350 GPD (53.72 gpm) = 0.1197 cfs Sanitary Sewer Hydraulic Analysis: The capacity of an 8-inch main is checked using Manning’s Equation: Q = (1.486/n)AR2/3S1/2 Q0.75 = 0.573 cfs > Qpeak = 0.1197 cfs ∴ adequate Based on these calculations, an 8-inch sewer main extension is more than adequate to carry the design flows for the West Side Flats Master Site Plan project. An analysis of the existing Norton Ranch Lift Station will be performed by HDR Engineering Inc. and is forthcoming at the time of this report. The necessary upgrades will be performed concurrently with installation of the West Side Flats sanitary sewer improvements. 8-inch PVC Pipe @ 75% Capacity Pipe Diameter =8 in Manning's (n)=0.013 (for PVC) Min. Slope (S) =0.004 ft/ft A = p(r2)0.35 ft2 P = 2pr 2.09 ft R = A/P 0.17 ft Qfull =0.764 cfs Q0.75 =0.573 cfs APPENDIX A WATERCAD MODEL RESULTS FlexTable: Junction Table Pressure (psi) Hydraulic Grade (ft) Demand (gpm) Elevation (ft) Label 714,967.4104,802.50J-56 714,967.3104,804.00J-57 714,967.3104,803.90PROHYD3 714,967.3004,804.00J-59 704,967.28144,804.80DJ9 704,967.2794,805.30DJ8 694,967.2494,807.10DJ7 694,967.2404,807.10J-63 694,967.2404,807.60J-64 694,967.2404,808.00PROHYD2 694,967.2304,807.90J-66 694,967.22144,808.70DJ6 684,967.2294,808.90DJ5 674,967.2194,811.40DJ4 674,967.2104,812.00J-70 674,967.2004,812.40J-71 684,967.2004,811.10J-72 674,967.2004,811.50J-73 674,967.2004,812.20J-75 674,967.2004,812.40PROHYD 1 674,967.20144,812.80DJ3 664,967.20144,814.80DJ2 664,967.2004,814.30J-79 654,967.2094,816.30DJ1 654,967.2004,817.10J-81 654,967.2004,817.70J-82 654,967.2004,818.00J-83 Page 1 of 127 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 7/2/2021 WaterCAD [10.03.03.72] Bentley Systems, Inc. Haestad Methods Solution Center180820WaterCAD Model.wtg FlexTable: Pipe Table Length (User Defined) (ft) Has User Defined Length? Headloss Gradient (ft/ft) Velocity (ft/s) Flow (gpm) Minor Loss Coefficient (Local) Hazen-Williams C MaterialDiameter (in) Length (Scaled) (ft) Label 1True0.0000.001010.000150.0PVC999.057P-51 0False0.0011.151010.000130.0Ductile Iron6.014P-60 0False0.0000.651010.500130.0Ductile Iron8.0364P-61 0False0.0000.0001.280130.0Ductile Iron6.013P-62 0False0.0010.651010.000130.0Ductile Iron8.013P-63 0False0.0000.651010.000130.0Ductile Iron8.062P-64 0False0.0000.56870.000130.0Ductile Iron8.037P-65 0False0.0000.50780.000130.0Ductile Iron8.0150P-66 0False0.0000.44690.100130.0Ductile Iron8.09P-67 0False0.0000.44690.000130.0Ductile Iron8.052P-68 0False0.0000.0001.280130.0Ductile Iron6.012P-69 0False0.0000.44690.350130.0Ductile Iron8.029P-70 0False0.0000.44690.350130.0Ductile Iron8.066P-71 0False0.0000.35550.350130.0Ductile Iron8.032P-72 0False0.0000.29460.350130.0Ductile Iron8.0153P-73 0False0.0000.23370.000130.0Ductile Iron8.037P-74 0False0.0000.23370.350130.0Ductile Iron8.057P-75 0False0.0000.0000.000130.0Ductile Iron8.0295P-76 0False0.0000.0000.000130.0Ductile Iron8.041P-77 0False0.0000.0000.000130.0Ductile Iron6.025P-78 0False0.0000.23370.000130.0Ductile Iron8.025P-79 0False0.0000.0000.000130.0Ductile Iron6.013P-80 0False0.0000.23370.350130.0Ductile Iron8.043P-81 0False0.0000.15230.350130.0Ductile Iron8.0125P-82 0False0.0000.0690.100130.0Ductile Iron8.027P-83 0False0.0000.0690.350130.0Ductile Iron8.098P-84 0False0.0000.0000.100130.0Ductile Iron8.044P-85 0False0.0000.0001.280130.0Ductile Iron8.067P-86 0False0.0000.0000.000130.0Ductile Iron8.062P-87 0False0.0000.0000.000130.0Ductile Iron6.014P-88 1True0.0000.0000.000150.0PVC99.035P-89 1True0.0000.0000.000150.0PVC99.020P-90 Page 1 of 127 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 7/2/2021 WaterCAD [10.03.03.72]Bentley Systems, Inc. Haestad Methods Solution Center180820WaterCAD Model.wtg Fire Flow Node FlexTable: Fire Flow Report Is Fire Flow Run Balanced? Pressure (Calculated System Lower Limit) (psi) Pressure (Calculated 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) Satisfies Fire Flow Constraints? Fire Flow Iterations Label True535360602,527602,52760True4J-56 True545460601,399601,39960True5J-57 True262620202,8691,5002,8691,500True12PROHYD3 True545460601,336601,33660True4J-59 True545460601,251741,23760True4DJ9 True545460601,189691,17960True4DJ8 True555560601,026691,01760True4DJ7 True555560601,010601,01060True5J-63 True555560609686096860True5J-64 True232320202,2761,5002,2761,500True12PROHYD2 True565660609396093960True5J-66 True565660608967488260True4DJ6 True565660608686985960True4DJ5 True575760607496974060True4DJ4 True575760607146071460True5J-70 True585860606866068660True5J-71 True585860606566065660True4J-72 True585860606406064060True4J-73 True575760606846068460True4J-75 True191920201,9691,5001,9691,500True3PROHYD 1 True585860606717465760True4DJ3 True595960605947458060True4DJ2 True585860605876058760True4J-79 True595960605306952160True4DJ1 True606060604946049460True4J-81 True606060604666046660True4J-82 True606060604516045160True4J-83 Page 1 of 127 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-16667/2/2021 WaterCAD [10.03.03.72]Bentley Systems, Inc. Haestad Methods Solution Center180820WaterCAD Model.wtg Pump Definition Detailed Report: HYD 2404 Element Details 168ID Notes HYD 2404Label Pump Curve Head(ft)Flow(gpm) 168.250 166.92200 165.78400 164.95600 163.85800 162.461,000 160.851,200 158.981,400 156.881,600 154.521,800 151.962,000 149.152,200 146.122,400 142.892,600 139.642,800 136.663,000 133.483,200 130.083,400 126.533,600 122.773,800 118.854,000 114.744,200 110.454,400 105.994,600 101.354,800 96.555,000 91.595,200 Page 1 of 327 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 7/2/2021 WaterCAD [10.03.03.72]Bentley Systems, Inc. Haestad Methods Solution Center180820WaterCAD Model.wtg Pump Definition Detailed Report: HYD 2404 Pump Curve Head (ft) Flow (gpm) 86.455,400 81.145,600 75.695,800 70.066,000 64.276,200 57.726,400 49.826,600 40.506,800 32.527,000 23.887,200 14.827,400 5.387,600 Pump Efficiency Type BestEfficiencyPointPump 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 2 of 327 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 7/2/2021 WaterCAD [10.03.03.72]Bentley Systems, Inc. Haestad Methods Solution Center180820WaterCAD Model.wtg Pump Definition Detailed Report: HYD 2404 Page 3 of 327 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 7/2/2021 WaterCAD [10.03.03.72]Bentley Systems, Inc. Haestad Methods Solution Center180820WaterCAD Model.wtg Pump Definition Detailed Report: HYD 2406 Element Details 256ID Notes HYD 2406Label Pump Curve Head(ft)Flow(gpm) 153.810 152.40200 151.11400 149.98600 148.50800 146.651,000 144.481,200 141.991,400 139.181,600 136.041,800 132.602,000 128.862,200 124.822,400 121.022,600 117.182,800 113.103,000 108.763,200 104.173,400 99.323,600 94.223,800 88.894,000 83.334,200 77.524,400 71.494,600 65.244,800 58.735,000 52.025,200 Page 1 of 327 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 7/2/2021 WaterCAD [10.03.03.72]Bentley Systems, Inc. Haestad Methods Solution Center180820WaterCAD Model.wtg Pump Definition Detailed Report: HYD 2406 Pump Curve Head (ft) Flow (gpm) 45.075,400 37.895,600 30.485,800 22.876,000 15.056,200 6.516,400 Pump Efficiency Type BestEfficiency 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 2 of 327 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 7/2/2021 WaterCAD [10.03.03.72]Bentley Systems, Inc. Haestad Methods Solution Center180820WaterCAD Model.wtg Pump Definition Detailed Report: HYD 2406 Page 3 of 327 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 7/2/2021 WaterCAD [10.03.03.72]Bentley Systems, Inc. Haestad Methods Solution Center180820WaterCAD Model.wtg Pump Definition Detailed Report: HYD 2408 Element Details 258ID Notes HYD 2408Label Pump Curve Head(ft)Flow(gpm) 148.380 146.93200 145.55400 144.30600 142.64800 140.611,000 138.181,200 135.371,400 132.231,600 128.721,800 125.932,000 123.142,200 120.072,400 116.722,600 113.122,800 109.293,000 105.213,200 100.893,400 96.323,600 91.553,800 86.544,000 81.324,200 75.854,400 70.204,600 64.294,800 58.205,000 51.885,200 Page 1 of 327 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 7/2/2021 WaterCAD [10.03.03.72]Bentley Systems, Inc. Haestad Methods Solution Center180820WaterCAD Model.wtg Pump Definition Detailed Report: HYD 2408 Pump Curve Head (ft) Flow (gpm) 45.355,400 38.615,600 31.665,800 24.516,000 17.156,200 9.376,400 Pump Efficiency Type BestEfficiency 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 2 of 327 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 7/2/2021 WaterCAD [10.03.03.72]Bentley Systems, Inc. Haestad Methods Solution Center180820WaterCAD Model.wtg Pump Definition Detailed Report: HYD 2408 Page 3 of 327 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 7/2/2021 WaterCAD [10.03.03.72]Bentley Systems, Inc. Haestad Methods Solution Center180820WaterCAD Model.wtg FlexTable: Pump Table Pump Head (ft) Flow (Total) (gpm) Hydraulic Grade (Discharge) (ft) Hydraulic Grade (Suction) (ft) Status (Initial) Pump DefinitionElevation (ft) LabelID 164.931014,967.434,802.50OnHYD 24044,802.50HYD 2404170 0.0004,811.504,967.20OffHYD 24064,811.50HYD 2406233 0.0004,818.104,967.20OffHYD 24084,818.10HYD 2408257 Page 1 of 127 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 7/2/2021 WaterCAD [10.03.03.72]Bentley Systems, Inc. Haestad Methods Solution Center180820WaterCAD Model.wtg APPENDIX B DEMAND JUNCTION MAP Scenario: Base P-77 P-71 P-74 P-73 P-72 P-51 P-89 P-70 P-88 P-68 P-86 P-85 P-66 P-84 P-65 P-83 P-64 P-63 P-79 P-60 P-82 P-81 P-75J-83 J-82 J-81 DJ1 J-79 DJ2 DJ3 PROHYD 1 J-75 J-73 J-72 J-71 J-70 DJ4 DJ5 DJ6 J-66 PROHYD2 J-64 J-63 DJ7 DJ8 DJ9 J-59 PROHYD3J-57 J-56 HYD 2404 HYD 2408 HYD 2406 R-4 R-2 R-3 Color Coding Legend Pipe: Diameter (in) <= 6.0 <= 8.0 <= 10.0 Other Page 1 of 127 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-166610/29/2020 WaterCAD [10.03.00.69]Bentley Systems, Inc. Haestad Methods Solution Center180820WaterCAD Model.wtg WEST SIDE FLATS WATER DEMAIN JUNCTION MAP APPENDIX C PHASED SANITARY SEWER ESTIMATES Westside Flats Sanitary Sewer Flow Estimates Phase 1 Number of Units = 48 dwelling units Contributing Area 8.78 acres Avg. Population Density = 2.17 persons/dwelling unit Avg. Daily Flow Rate = 65 gal/person/day Assumed Infiltration Rate = 150 gal/acre/day Total Population = 104 persons Infiltration = 1317.00 gal/day 0.91 gpm Peaking Factor = 4.24 (Harmon Formula) Peak Flow Rate = 30023 gal/day (Peak flow + Infiltration) 20.85 gpm 0.0465 cfs Phase 2 Number of Units (Phase 2) = 42 dwelling units Number of Units (Phase 1 )= 48 dwelling units Total Number of Units (Phases 1 & 2) 90 Contributing Area 8.78 acres Avg. Population Density = 2.17 persons/dwelling unit Avg. Daily Flow Rate = 65 gal/person/day Assumed Infiltration Rate = 150 gal/acre/day Total Population = 195 persons Infiltration = 1317.00 gal/day 0.91 gpm Peaking Factor = 4.15 (Harmon Formula) Peak Flow Rate = 53999 gal/day (Peak flow + Infiltration) 37.50 gpm 0.0835 cfs Phase 3 Number of Units (Phase 3)= 42 dwelling units Number of Units (Phase 2) = 42 dwelling units Number of Units (Phase 1)= 48 dwelling units Total Number of Units (Phases 1, 2&3) 132 Contributing Area 8.78 acres Avg. Population Density = 2.17 persons/dwelling unit Avg. Daily Flow Rate = 65 gal/person/day Assumed Infiltration Rate = 150 gal/acre/day Total Population = 286 persons Infiltration = 1317.00 gal/day 0.91 gpm Peaking Factor = 4.09 (Harmon Formula) Peak Flow Rate = 77350 gal/day (Peak flow + Infiltration) 53.72 gpm 0.1197 cfs