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HomeMy WebLinkAbout15 - Design Report - Valley Meadows - Water, Sewer DESIGN REPORT WATER AND SEWER SYSTEM VALLEY MEADOWS SUBDIVISION Prepared for: Fortin Construction, LLC P.O. Box 11811, Bozeman, MT 59719 Prepared by: C&H Engineering and Surveying, Inc. 1091 Stoneridge Drive, Bozeman, MT 59718 (406) 587-1115 C� 10. Project Number: 14328 May 2015 INTRODUCTION The proposed Valley Meadows Subdivision is a 62-lot major subdivision located on an 8.69 acre parcel legally described as A Part of Tract 6 of Smith Subdivision, City of Bozeman, Gallatin County, Montana and located in the Northwest Quarter of Section 11, Township 2 South,Range 5 East of P.M.M., Gallatin County,Montana. It is located south of Durston Road along the northerly extension of Meriwether Avenue. The proposed subdivision will connect to existing City of Bozeman water and sewer mains. WATER DISTRIBUTION SYSTEM Existing water mains in the area utilized for this project include a 10-inch ductile iron pipe (DIP) main located in Durston Road, an 8-inch DIP main stub at the south end of the proposed subdivision in Meriwether Avenue and a 6-inch existing water main stub at the east side of the subdivision on West Villard Street. There is also an existing 8-inch stub extending into the proposed subdivision off of the 10-inch main in Durston Road;this stub will not be utilized for the project. A WaterCAD analysis is enclosed (Appendix A of this report) analyzing all mains installed with this project. The connection to the existing system is modeled as a pump with characteristics matching pressure/flow data measured by the City of Bozeman Water Department. Water Distribution System Demands The design parameters used herein are according to the City of Bozeman Design Standards and Specifications Policy (DSSP) dated March 2004. 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= 1.0) Maximum Day Demand (Peaking Factor=2.3) Peak Hour Demand (Peaking Factor= 3.0) Water Demands (62 dwelling units) Average Day Demand = 62 d.u. x 2.l l persons/d.u. x 170 gpcpd=22239 gpd = 15.44 gpm Maximum Day Demand = 15.44 gpm x 2.3 = 35.52 gpm Peak Hour Demand = 15.44 gpm x 3.0 =46.33 gpm Water Distribution System Hydraulic Analysis A water distribution model was created using WaterCAD Version 6.5 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 1.0, 2.3 and 3.0 respectively. AVG. MAX. JUNCTION # OF DAY DAY PEAK NODE LOTS GPM GPM HOUR GPM J-1 23 5.73 13.18 17.19 J-3 20 4.98 11.46 14.95 J-6 12 2.99 6.88 8.97 J-7 7 1.74 4.01 5.23 Total 62 15.44 35.52 46.33 Static, residual and pitot pressures were measured by the City of Bozeman Water Department for the 8-inch water main in Meriwether Avenue. The Hydrant Pressure/Flow Request Form is attached in Appendix A of this report. The results are shown below: Location Hydrant# Static Pressure Pitot Pressure Residual Pressure Meriwether Ave 1634 107# (1,737 GPM) Droulliard Ave. 1633 132# 124# Static pressure for the 8"water main in Droulliard Ave.was measured by the City of Bozeman and found to be 132# at the Droulliard/Cameahwait hydrant (#1633). This project will also connect to the 10" ductile iron water main in Durston, and the 6" existing water main in Villard Street;these connections were conservatively modelled as dead ends for the purposes of this report. This flow/pressure information was used to develop relationships between static head and flow at the Meriwether tie in point. This relationship was simulated in the WaterCAD model using a pump at the connection point. 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 pump. The input data and the pump curve are included in Appendix A of this report. Water Distribution System Design Summary The proposed 8-inch DIP water mains provide adequate capacity with regards to the Peak Hour Demands. The flows and pressures within the system for the Peak Hour Demands were generated using WaterCAD and can be found in Appendix A of this 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 all hydrant junctions satisfy fire flow constraints (residual pressure > 20 psi, flow rate > 1500 gpm), while providing service to lots at peak hour demand. The results of the analysis at peak hourly flow are given in Appendix A of this report. SANITARY SEWER SYSTEM Sewer main lines will be installed in Meriwether Avenue and will flow into the existing 8-inch main in Durston Road at the north boundary of the subdivision. Sanitary Sewer Design Load The flow rates used herein are according to the City of Bozeman Design Standards and Specifications Policy, March 2004. The peaking factor for the design area is determined by calculating the equivalent population and inserting the population into the Harmon Formula. An 8-inch main is the minimum diameter allowed within the City of Bozeman. All new sewer lines shall be sized to flow at no more than 75% of capacity for peak hour conditions. Using the city average of 2.11 persons per household the equivalent population for the service area is calculated. Valley Meadows: Equivalent Population; (2.11 persons/d.u.)(62 d.u.) = 131 persons Assumed infiltration rate: (150 gal/acre/day) (8.69 acres)= 1304 gal/day Total Design Load: The total population and infiltration rate for Valley Meadows Subdivision is 131 persons, and 1304 gal/day. The peak flow rate is calculated by multiplying the City`s design generation rate of 89 gallons per capita per day by the population, multiplying by the peaking factor, and adding the infiltration rate: Harmon Formula: Peaking Factor=(18 +Po.$)/(4 +PO-) where: P =Population in thousands Peaking Factor= (18 + 0.1310-5)/(4 + 0.131") Peaking Factor=4.21 Peak Flow Rate: (89 gal/person/day)(131 persons)(4.21) + 1304 gal/day = 50,388 gal/day =34.99 gpm (0.0780 cfs) Onsite Sanitary Sewer Hydraulic Analysis The capacity of an 8-inch main is checked using Manning's Equation: Q = (1.4861n)AWI'S" For an 8-inch PVC sewer main: Manning's n =0.013 for PVC Minimum Slope = 0.004 ft/ft A =area= (,K/4)d 2= (a/4)(8/12)2= 0.34907 ft2 P =perimeter=2nr=2n(4/12)=2.0944 ft R=hydraulic radius =A/P = 0.34907/2.0944 = 0.16667 ft Reis = 0.30105 ft S = 0.004 ft/ft S'/2 =0.0632 ft/ft Qfuu = (1.486/0.013)(0.34907)(0.30105)(0.0632) = 0.7592 cfs QO.75 = (0.75)(0.7592) = 0.5694 cfs Based on these calculations, an 8-inch sewer main is more than adequate to carry the design flows for the subdivision. Offsite Sanitary Sewer Impact Analysis The existing 8" sanitary sewer main in Durston flows west to the SID 621 18"trunk sewer,then north to a manhole near the intersection of W. Oak Street and Davis Lane. This is a unique manhole with two outlet pipes. From this manhole, flows may go either 1) east through the Baxter Interceptor, discharging to the 19t1'Avenue/1 I"'Avenue Interceptor, and finally discharging to the WWTP Interceptor or 2) north through the Davis interceptor, discharging to the 27"' Avenue/Cattail Creek Interceptor, and finally joining flows from the 19''Avenue/I I"' Avenue Interceptor into the WWTP Interceptor. Based on the Bozeman Wastewater Facilities Plan(2007), all the affected sewers are currently flowing at less than 50% of capacity for the peak day model. The percent increase in flow for the SID 621 trunk main is calculated below: SID 621 Trunk Main Capacity (18"Asbestos Concrete Sewer Main) Q = (1.486/n)AR21S11 Manning's n =0.013 Estimated Slope = 0.01 ft/ft A = area= (7u/4)d 2=(7E/4)(18/12)2= 1.7671 ft2 P =perimeter= 2ar=2n(9/12) =4.7124 ft R=hydraulic radius =A/P =0.3750 ft R2' = 0.5200 ft S = 0.01 ft/ft S 1/2= 0.1 ft/ft Qfuti = (1.486/0.013)(1.7671)(0.5200)(0.01) = 10.5043 cfs Increase in flow for SID 621 trunk main= 0.0780 cfs/10.5043 cfs=0.74% The impact on downstream interceptors is calculated below. Calculations are based on the Valley Meadows Peak Flow Rate of 0.0780 cfs (0.0504 MGD) and interceptor capacities per the Bozeman Wastewater Facilities Plan(2007). The Davis interceptor was constructed in 2007 and is not included in the 2007 plan or the calculations below. Interceptor Capacity (MGD) Increase (%) Baxter 8 0.63 19" Ave/1 lt'Ave 16 0.32 27t'Ave/Cattail Creek 13 0.39 W WTP 22 0.23 APPENDIX A WATERCAD MODEL & COB HYDRANT DATA Scenario: Peak Hour 40 J-8 N J-7 /J-6 P-8 P-3 P 5 J-2 J-3 J_q J-5 co J-1 V- Q�g PMP-1 R-1 Title:Valley Meadows Project Engineer:Taylor Balian z:\...\watercad\14328 watercad model.wcd C&H Engineering&Surveying,Inc. WaterCAD v6.5[6.5120] 12/08/14 09:42:10 AM 0 Haestad Methods, Inc. 37 Brookside Road Waterbury,CT 06708 USA +1-203-755-1666 Page 1 of 1 1 2 O 2 O CITY OF BOZEMAN Shaping Our Future 7ogether HYDRANT PRESSURE/FLOW REQUEST FORM Date: 9/9/14 Location Hydrant# Static Pressure Pito Pressure Residual Pressure Meriwether Ave 1634 107# Droulliard Ave 1633 132# 124# Requested By: Taylor Balian Fax # Nozzle Size Flowed: 2.5" Done By: ES /AO Comments: 1737 GPM 939-94,G— `i 938 4990 i 1095 �'i00118 #7' 1`2039I 937 80— '827 `989 i f f 3� 163$ 856' 1007 1010 f, 857 117 7, 988 (' `(� 1490 858 994 ii (( `;1635 1632 11009 I _ — _ . I'Ill 0 0 821� 828 987 1003 8,) 637 51 , 1 1631 € 1008iloo- = ' �) If 985 i 2295 1986 j 860 ( ';2379 24 L 't .._. 2354 2382 �� ` 1004 lcK?2 `983 , 1223 Pump Curve Calculations: Pump#1 (Hydrant#1634, Camehawait St./Meriwether Ave.) Static Pressure (Ps) = 132 @ hydrant#1633 Pitot Pressure (Pp)= 107 Residual Pressure (Pr) = 124 @ hydrant#1633 Qf= 1737 Q=Qf*((Ps-P)/(Ps-Pr))(o.s4) Pressure Flow Head 132 0.00 304.62 130 821.65 300.00 125 1616.16 288.46 120 2162.17 276.92 115 2609.60 265.38 110 2999.44 253.85 105 3350.18 242.31 100 3672.08 230.77 95 3971.55 219.23 90 4252.91 207.69 85 4519.23 196.15 80 4772.80 184.62 75 5015.38 173.08 70 5248.35 161.54 65 5472.83 150.00 60 5689.72 138.46 55 5899.79 126.92 50 6103.67 115.38 45 6301.90 103.85 40 6494.96 92.31 35 6683.25 80.77 30 6867.13 69.23 25 7046.91 57.69 20 7222.86 46.15 15 7395.23 34.62 10 7564.24 23.08 5 7730.10 11.54 0 7892.98 0.00 Detailed Report for Pump: PMP-. Scenario Summary Scenario Peak Hour Active Topology Alternative Base-Active Topology Physical Alternative Base-Physical Demand Alternative Base-Demand Initial Settings Alternative Base-Initial Settings Operational Alternative Base-Operational Age Alternative Base-Age Alternative Constituent Alternative Base-Constituent Trace Alternative Base-Trace Alternative Fire Flow Alternative Base-Fire Flow Capital Cost Alternative Base-Capital Cost Energy Cost Alternative Base-Energy Cost User Data Alternative Base-User Data Global Adjustments Summary Demand <None> Roughness <None> Geometric Summary X 9,890.39 ft Upstream Pipe P-19 Y 8,924.10 ft Downstream Pipe P-4 Elevation 4,801.87 ft Pump Definition Summary Pump Definition Pump Definition-1 Initial Status Initial Pump Status On Initial Relative Speed Factor 1.00 Calculated Results Summary Time Control Intake Discharge Discharge Pump Relative Calculated (hr) Status Pump Pump (gpm) Head Speed Water Grade Grade (ft) Power (ft) (ft) (Hp) 0.00 On 4,801.87 5,106.46 46.36 304.59 1.00 3.56 Pump Head Curve 350.0 PMP-1 (Relative Speed Factor = 1.00) 300.0• 250.0 200.0 N� = 150.0 100.0 50.0 0.0 0.0 1000.0 2000.0 3000.0 4000.0 5000.0 6000.0 7000.0 8000.0 Discharge (gpm) Title:Valley Meadows Project Engineer:Taylor Balian z:\...\watercad\14328 watercad model.wcd C&H Engineering&Surveying,Inc. WaterCAD v6.5[6.5120] 12/08/14 09:29:41 AM ©Haestad Methods, Inc. 37 Brookside Road Waterbury,CT 06708 USA +1-203-755-1666 Pagel Calculation Results Summary Scenario:Peak Hour [Analysis Started] [Fire Flow] [Steady State] 0:00:00 Balanced after 2 trials;relative flow change=0.000476 Trial 1:relative flow change=157.206894 Trial 2:relative flow change=0.000476 Flow Summary Flow Supplied 46.35 gpm Flow Demanded 46.34 gpm Flow Stored 0.00 gpm 0:00:00 Reservoir R-1 is emptying [Analysis Ended] Title:Valley Meadows Project Engineer:Taylor Balian z:\...\watercad\14328 watercad model.wcd C&H Engineering&Surveying,Inc. WaterCAD v6.5[6.5120] 12/08/14 09:34:29 AM ©Haestad Methods, Inc. 37 Brookside Road Waterbury,CT 06708 USA +1-203-755-1666 Page 1 of 1 F C\j - 0 NLO - co 0 a) ca (D E F- > .0 L: 0 E a) < a) d .ENS S 0) c "0 cli Cf) C) 0 M M C) 0 M 0 co m w Q) E O O O C6 C) 6 N - N N N m 2 fa- 75.9 C: U) w (L o in cL N 2! 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