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Home My WebLink AboutApp. A_Water & Sewer Design Report_2019-12-12 Design Report - Page 2 of 6 INTRODUCTION The Parklands Subdivision project is a major subdivision that proposes to create 1 multi-household lot, 9 single-household lots, 1 park, and 1 common open space. For the purpose of this report, the multi-family lot was assessed at 11 dwelling units to meet the 8 dwelling units per acre net residential density. Water for domestic use and fire protection will be provided by connections to the City of Bozeman water system. PROPOSED WATER LAYOUT AND EXISTING FACILITIES There is an existing 8” water main in Village Downtown Boulevard running under the north side of the roadway. The existing 8” main will be live tapped on the north end and the south side of the project. A new 8” water main will loop down Front Street and between Block 1 and Block 2 before tying in to the existing water main in Village Downtown Boulevard. Two existing hydrants: #1857 and #1858 will service Block 1 and two additional hydrants will be installed with this project to service Block 2. One new hydrant is proposed at the intersection of Alley and Front Street and another is proposed within the Alley. A valve will be located at Front St. and the Alley intersection which will allow the new hydrants to be isolated. WATER SYSTEM DESIGN A WaterCAD analysis is enclosed at the end of the report analyzing the existing 8-inch water main extension proposed 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. The hydrant data used was for hydrant #5, located at East Mendenhall Street and North Broadway Avenue. The flow test was conducted for the original Village Downtown PUD is 2002 and as such is older water system data. It is assumed that this hydrant flow data is still a reasonable representation of site conditions. The original pump curve from the Village Downtown PUD water design report was used at the connectin 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= Design Report - Page 3 of 6 residual pressure during test, Ps = static pressure and P = residual pressure at the desired flow rate. Ps = 125 PSI Pr = 110 PSI Qf = 1,635 GPM 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 and 80 were chosen for ductile iron pipe and cast iron pipe, respectively. The C-factor of 80 was chosen for cast iron due to its age. Cast iron pipe typically has a higher friction loss than ductile iron, especially with older pipe. DEMAND FORECASTING 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. 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) Design Report - Page 4 of 6 Residential Water Demands (Junction 57 – Lot 1, Block 1 and Lots 1-9, Block 2) Average Day Demand = 20 d.u. x 2.11 persons/d.u. x 170 gpcpd = 7,174 gpd = 4.98 gpm Maximum Day Demand = 5.0 gpm x 2.3 = 11.45 gpm Peak Hour Demand = 5.0 gpm x 3.0 = 14.94 gpm Parklands Demand Summary (average day, max day and peak hour): DEMAND JUNCTION NODE DWELLING UNITS (D.U.) POPULATION (RES.) 2.11 PEOPLE PER D.U. AVERAGE DAY GPM (170 GALLONS PER DAY PER PERSON) MAX. DAY GPM PEAK HOUR GPM J-57 20 42 5.0 11.5 14.9 Total 20 42 5.0 11.5 14.9 CONCLUSIONS The 8-inch DIP water main does provide adequate capacity with regards to the Peak Hour Demands. The flows and pressures within the system for the Peak Hour Demands were generated with the WaterCAD program and can be found at the end of the report. The capacity of the system to meet fire flow requirements was tested by running a steady state fire flow analysis for all junctions at fire hydrant locations. The model shows that existing water system will satisfy fire flow constraints (residual pressure > 20 psi, flow rate > 1500 gpm), while providing service to the buildings at peak hour. The results of the analysis at peak hourly flow are given at the end of the report. SEWER SYSTEM An existing 12” asbestos cement sewer main runs from north to south through the proposed Parklands Subdivision. This existing gravity interceptor line is referred to as the Front Street Interceptor in the 2015 Wastewater Facility plan and is indicated as a near-term improvement. This sanitary sewer main will be relocated with this project and the main will be upgraded to a 21” PVC SDR 35 main. The new main size was determined based on the City of Bozeman Capital Improvements Plan recommended upgrades to the existing system. The existing 12” asbestos Design Report - Page 5 of 6 cement main will be replaced downstream of existing manhole D0419 installed with SID 425. At this location, a new 60” sanitary sewer manhole will be installed and the new gravity main will run northeast to future Front Street. From here, the main will head northwest through the future Front Street right-of-way and tie back in to the existing sanitary sewer manhole D0421 installed with SID 425 north of Village Downtown Boulevard. DESIGN REQUIREMENTS The flow rates used herein are according to Shawn Kohtz of the City of Bozeman Engineering Department. He has stated that the City Design Standards and Specifications Policy will be updated to change the standard from 89 gpcd with an occupancy of 2.11 people per unit to 65 gpcd with an occupancy of 2.17 people per unit. The peaking factor for the design area is determined by figuring the equivalent population and inserting the population into the Harmon Formula. Using the city average of 2.17 persons per household, the equivalent is calculated. Sewer Flows from Parklands Subdivision: Equivalent Population = (2.17 persons/dwelling unit)(20 units) = 43.40 persons Harmon Formula: Peaking Factor = (18 + P0.5)/(4 + P0.5) where: P = Population in thousands Peaking Factor = (18 + 0.049910.5)/(4 + 0.049910.5) Peaking Factor = 4.33 Assumed infiltration rate = 150 gallons/acre/day = 150 (11.84 acres) = 1776 gal/day The peak flow rate is calculated by multiplying the City's design generation rate of 65 gallons per capita per day by the population, multiplying by the peaking factor, and adding the infiltration rate: Peak Flow Rate = 65 gpcpd (43.40 persons) (4.33) + 1776 gpd= 13990.93 gpd = 9.72 gpm (0.0217 cfs) The capacity of a 21-inch main is checked using Manning’s Equation: Design Report - Page 6 of 6 Qfull = (1.486/n)AR2/3S1/2 For the 21-inch main: Manning's n = 0.013 for PVC Pipe Minimum Slope = 0.004 ft/ft A = area = (3.14/4)d 2 = (3.14/4)(21/12)2 = 2.404 ft2 P = perimeter = 2(3.14)r = 2(3.14)(10.5/12) = 5.495 ft R = hydraulic radius = A/P = 2.404/5.495 = 0.4375 ft R2/3 = 0.5763 ft S = 0.004 ft/ft S1/2 = 0.0632 ft/ft Qfull = (1.486/0.013)(2.404)(0.5763)(0.0632) = 10.01 cfs The 2015 Wastewater Facility plan indicates that the existing Front Street Interceptor in the project vicinity is flowing at 50-75% of maximum depth. The current flow rate in the existing 12” asbestos cement main at this depth is calculated below from the online Haws-EDC calculator: Based on these calculations, the 21-inch sewer line is more than adequate to carry the additional design flows created by this subdivision. 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 WWatertown, CT 06795 USA +1-203-755-16667/28/2017 Bentley WaterCAD CONNECT Edition[10.00.00.50]Bentley Systems, Inc. Haestad Methods SolutionCenterWATER MAIN MODEL 7-26-17.wtg Scenario: Base P-70P-69 P-88P-79P-82P-91P-76P-80 P-58P-77P-74P-54Page 1 of 127 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-16667/28/2017 Bentley WaterCAD CONNECT Edition[10.00.00.50]Bentley Systems, Inc. Haestad Methods Solution CenterWATER MAIN MODEL 7-26-17.wtg FlexTable: Pipe Table Headloss Gradient (ft/ft) Hydraulic Grade (Stop) (ft) Hydraulic Grade (Start) (ft) Velocity (ft/s) Flow (gpm) Minor Loss Coefficient (Derived) Has Check Valve? Hazen-Williams C MaterialDiameter (in) Length (User Defined) (ft) Label 0.0005,099.455,099.450.0001.870False80.0Cast iron6.0334P-52 0.0005,099.455,099.450.0000.740False80.0Cast iron6.0433P-53 0.0005,099.455,099.450.0002.470False80.0Cast iron6.026P-54 0.0005,099.455,099.450.0001.480False80.0Cast iron6.0265P-55 0.0005,099.455,099.450.0002.270False80.0Cast iron10.0394P-58 0.0005,099.435,099.430.0351.670False130.0Ductile Iron8.0201P-69 0.0005,099.435,099.430.01-10.740False130.0DuctileIron8.0419P-70 0.0005,099.435,099.430.01-10.800False130.0Ductile Iron8.010P-72 0.0005,099.435,099.430.01-10.740False130.0DuctileIron8.0260P-73 0.0005,099.435,099.430.0001.280False130.0DuctileIron8.0112P-74 0.0005,099.435,099.430.0000.000False130.0Ductile Iron6.00P-75 0.0005,099.435,099.430.0230.350False130.0DuctileIron8.0300P-76 0.0005,099.435,099.430.0231.280False130.0Ductile Iron8.0143P-77 0.0005,099.435,099.430.12190.350False130.0DuctileIron8.065P-79 0.0005,099.435,099.430.0001.940False130.0DuctileIron6.010P-80 0.0005,099.435,099.430.0000.000False130.0Ductile Iron6.010P-81 0.0005,099.435,099.430.0000.000False130.0DuctileIron6.015P-82 0.0005,099.435,099.450.12192.720False130.0Ductile Iron8.01,365P-84 0.0005,099.455,099.450.0000.740False130.0DuctileIron8.0741P-85 Page 1 of 227 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA+1-203-755-16667/28/2017 Bentley WaterCAD CONNECT Edition[10.00.00.50]Bentley Systems, Inc. Haestad Methods Solution CenterWATER MAIN MODEL 7-26-17.wtg FlexTable: Pipe Table Headloss Gradient (ft/ft) Hydraulic Grade (Stop) (ft) Hydraulic Grade (Start) (ft) Velocity (ft/s) Flow (gpm) Minor Loss Coefficient (Derived) Has Check Valve? Hazen-Williams C MaterialDiameter (in) Length (User Defined) (ft) Label 0.0005,099.455,099.450.0002.470False80.0Cast iron6.034P-86 0.0004,827.004,827.000.0000.000False130.0DuctileIron99.01P-87 0.0005,099.455,099.450.0000.000True130.0DuctileIron99.01P-88 0.0005,099.455,099.450.0002.270False80.0Cast iron6.0658P-89 0.0004,811.004,811.000.00190.000False130.0DuctileIron99.01P-90 0.0005,099.455,099.450.00190.000True130.0Ductile Iron99.01P-91 Page 2 of 227 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA+1-203-755-16667/28/2017 Bentley WaterCAD CONNECT Edition[10.00.00.50]Bentley Systems, Inc. Haestad Methods Solution CenterWATER MAIN MODEL 7-26-17.wtg FlexTable: Junction Table Pressure (psi) Hydraulic Grade (ft) Demand (gpm) Demand CollectionZoneElevation (ft) LabelID 1155,099.450<Collection: 0 items><None>4,833.00BUTTONWOOD AVE145 1155,099.450<Collection: 0 items><None>4,833.00E. MAIN147 1415,099.430<Collection: 0 items><None>4,773.00HYD 1187 1425,099.430<Collection: 0 items><None>4,771.00HYD 2199 1255,099.450<Collection: 0 items><None>4,811.00HYD5MENDENHALL AND BROADWAY201 1185,099.450<Collection: 0 items><None>4,827.00HYD211143 1185,099.450<Collection: 0 items><None>4,827.00HYD234139 1385,099.430<Collection: 0 items><None>4,781.00HYD1857195 1415,099.430<Collection: 0 items><None>4,774.00HYD1858197 1265,099.450<Collection: 0 items><None>4,808.00J-46156 1415,099.432<Collection: 1 items><None>4,774.00J-54171 1375,099.4311<Collection: 1 items><None>4,783.00J-55174 1415,099.436<Collection: 1 items><None>4,773.00J-56177 1425,099.430<Collection: 0 items><None>4,771.00J-57179 1425,099.430<Collection: 0 items><None>4,771.00J-58182 1415,099.430<Collection: 0 items><None>4,773.00J-59185 1415,099.430<Collection: 0 items><None>4,774.00J-61189 1385,099.430<Collection: 0 items><None>4,781.00J-62192 1255,099.450<Collection: 0 items><None>4,811.00J-67204 1255,099.450<Collection: 0 items><None>4,811.00NORTH BROADWAY149 1245,099.450<Collection: 0 items><None>4,812.00S. WALLACE AVE154 Page 1 of 127 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA+1-203-755-16667/28/2017 Bentley WaterCAD CONNECT Edition[10.00.00.50]Bentley Systems, Inc. Haestad Methods Solution CenterWATER MAIN MODEL 7-26-17.wtg FlexTable: Pump Table Pump Head (ft) Flow (Total) (gpm) Hydraulic Grade (Discharge) (ft) Hydraulic Grade (Suction) (ft) Status (Initial)Pump DefinitionElevation (ft) LabelID 0.0005,099.454,827.00OffHydrant 2344,827.00PMP-3207 288.45195,099.454,811.00OnHydrant 54,811.00PMP-4218 Page 1 of 127 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA+1-203-755-16667/28/2017 Bentley WaterCAD CONNECT Edition[10.00.00.50]Bentley Systems, Inc. Haestad Methods Solution CenterWATER MAIN MODEL 7-26-17.wtg Pump Definition Detailed Report: Hydrant 5 Element Details 221ID Notes Hydrant 5Label Pump Curve Head (ft) Flow (gpm) 288.460 276.92903 230.772,154 184.622,959 138.463,609 92.314,172 46.154,676 0.005,138 Pump Efficiency Type Constant EfficiencyPump Efficiency Type %100.0Motor Efficiency %100.0Constant Efficiency FalseIs Variable Speed Drive? 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 WWatertown, CT 06795 USA +1-203-755-16667/28/2017 Bentley WaterCAD CONNECT Edition[10.00.00.50]Bentley Systems, Inc. Haestad Methods SolutionCenterWATER MAIN MODEL 7-26-17.wtg Pump Definition Detailed Report: Hydrant 5 Graph Head(ft)300.00 275.00 250.00 225.00 200.00 175.00 150.00 125.00 100.00 75.00 50.00 25.00 0.00 PumpEfficiency(%)110.0 100.0 90.0 80.0 70.0 60.0 50.0 40.0 30.0 20.0 10.0 0.0 Flow (gpm) 5,0004,5004,0003,5003,0002,5002,0001,5001,0005000 Page 2 of 227 Siemon Company Drive Suite 200 WWatertown, CT 06795 USA +1-203-755-16667/28/2017 Bentley WaterCAD CONNECT Edition[10.00.00.50]Bentley Systems, Inc. Haestad Methods SolutionCenterWATER MAIN MODEL 7-26-17.wtg Fire Flow Node FlexTable: Fire Flow Report Junction w/ Minimum Pressure (System) Pressure (Calculated System 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 (N/A)(N/A)(N/A)20(N/A)(N/A)(N/A)1,500HYD234 (N/A)(N/A)(N/A)20(N/A)(N/A)(N/A)1,500HYD211 (N/A)(N/A)(N/A)20(N/A)(N/A)(N/A)1,500BUTTONWOODAVE (N/A)(N/A)(N/A)20(N/A)(N/A)(N/A)1,500E. MAIN (N/A)(N/A)(N/A)20(N/A)(N/A)(N/A)1,500NORTHBROADWAY (N/A)(N/A)(N/A)20(N/A)(N/A)(N/A)1,500S. WALLACE AVE (N/A)(N/A)(N/A)20(N/A)(N/A)(N/A)1,500J-46 (N/A)(N/A)(N/A)20(N/A)(N/A)(N/A)1,500J-54 (N/A)(N/A)(N/A)20(N/A)(N/A)(N/A)1,500J-55 (N/A)(N/A)(N/A)20(N/A)(N/A)(N/A)1,500J-56 (N/A)(N/A)(N/A)20(N/A)(N/A)(N/A)1,500J-57 (N/A)(N/A)(N/A)20(N/A)(N/A)(N/A)1,500J-58 (N/A)(N/A)(N/A)20(N/A)(N/A)(N/A)1,500J-59 J-593320202,4301,5002,4301,500HYD 1 (N/A)(N/A)(N/A)20(N/A)(N/A)(N/A)1,500J-61 (N/A)(N/A)(N/A)20(N/A)(N/A)(N/A)1,500J-62 J-553220202,5941,5002,5941,500HYD1857 J-613220202,5091,5002,5091,500HYD1858 J-583320202,4851,5002,4851,500HYD 2 (N/A)(N/A)(N/A)20(N/A)(N/A)(N/A)1,500 HYD5MENDENHALLANDBROADWAY (N/A)(N/A)(N/A)20(N/A)(N/A)(N/A)1,500J-67 Page 1 of 127 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA+1-203-755-16667/28/2017 Bentley WaterCAD CONNECT Edition[10.00.00.50]Bentley Systems, Inc. Haestad Methods Solution CenterWATER MAIN MODEL 7-26-17.wtg