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HomeMy WebLinkAbout07 - Design Report - Annie Street Cottages - Wastewater Wastewater Design Report ANNIE STREET COTTAGES STREET AND UTILITY IMPROVEMENTS WASTEWATER SYSTEM DESIGN REPORT A. General This report will give an overview of the existing sanitary sewer capacity and proposed wastewater collection system of the area being served for the Annie Street Cottages Project. The proposed condominium development will consist of 31 units. The zoning for the 5.0 acre area served by the sewer main extension is R2. Construction for the first phase of the development is expected to begin in fall of 2007. Included in this report is a description of the proposed wastewater collection system and design parameters and an analysis of the impact on the existing downstream wastewater collection system. Once the wastewater system is constructed and approved, the system will become a part of the City of Bozeman system. The following references were used in the wastewater facilities design and capacity analysis: a. COB Design Standards and Specifications Guide,March, 2004 b. COB Modifications to Montana Public Works Standard Specifications(MPWSS) c. City adopted MPWSS and Adopted Addenda d. COB Wastewater Facility Plan e. WQB Circular No. 2 f. City of Bozeman Zoning Map B. Capacity Analysis The effluent generated from the proposed development will flow to the northwest into an existing City of Bozeman sanitary sewer main located in Phase I of the Oak Springs Subdivision at Meagher and.Annie. The procedures and parameters outlined in the COB Design Standards and Specifications Guide were used in the design of the sewer infrastructure for the proposed development. The new sewer main was sized to flow at no more than 75-percent of full capacity at peak hour conditions. An average daily flow of 72-gallons per capita per day was used to determine flows generated. An infiltration rate of 150 gallons/acre/day was added to the design peak flow. A Manning coefficient of 0.013 was used for PVC pipe. Using the City's average of 2.54 persons per residents it is anticipated the population in this development will be 30 persons. Equivalent Population: 2.54 persons/unit x 31 units=79 persons A peaking factor was calculated based on the following formula: Qmax i Qave=(18 +Po-')/(4+P°.5) (P=Population/thousands) The average daily flow based on the estimated population of 79 residents is: 79 residents x 72 gpcpd= 5,688 gpd Annie Street Cottages—Wastewater Design Report Page 1 of 3 Based on the equivalent population, a peaking factor of 4.27 was calculated. The calculated peaking factor is included in the appendix of this report. The peak flow rate anticipated from the development based on an average daily flow of 5,688 gallons with an infiltration rate of 150 gal/acre/day using 72-gallons per capita per day is: Peak Flow Rate=5,688 gpd x 4.27+750 gpd =25,038gpd = 17.39 gpm =0.039 cfs The sewer main size for the development will be an 8-inch,based on minimum required pipe size. Table 1 summarized the capacity of the proposed sewer. Calculations are provided in the appendix of this report. TABLE 1 PIPE CAPACITY Station Pipe Size Pipe Slope Pipe Capacity 3/4 Full(cfs) 10+00— 12+69 8-inch 0.4% 0.70 12+69— 13+97 8-inch 0.4% 0.70 13+97— 15+27 8-inch 0.5% 0.78 16+00—20+00 8-inch 1.5% 1.35 30+00—33+12 8-inch 0.8% 0.99 33+12—35+16 8-inch 1.5% 1.35 40+00—41+68 8-inch 0.4% 0.70 As shown in Table 1, all sections of the proposed 8-inch pipe is adequate for the anticipated peak flow of approximately 0.0385 cfs generated from the development. C. Proposed Collection System PVC pipe meeting COB specifications will be used for all the sewer mains. The sewer mains will be 8-inch diameter with a maximum manhole spacing of 400 feet and a manhole barrel size of 48- inches. Manholes will be constructed according to COB specifications. All sewer services will be 4-inch PVC installed at 2% minimum grade. Sewer services will connect into the main with in-line gasketed wyes. A 4-inch sewer service with a grade of 2.0 % can convey approximately 60 gpm at 50%capacity. A plan and profile of the proposed sewer extension is shown in the appendix of this report. The sewer main will be located within a 30-foot wide utility easement and located a minimum of 10- feet from the proposed public water main. D. Downstream Capacity Analysis Information regarding the downstream capacity of the existing public sanitary sewer collection system was provided from the design report prepared for the Oak Springs Subdivision. The design report indicates the sewer system to which the Annie Street Cottages sewer will discharge to will have peak flow rate of 0.3664 cfs,or 48.26%full. Annie Street Cottages—Wastewater Design Report Page 2 of 3 E. Conclusion Adding the Annie Street Cottages sewer peak flow rate of 0.039 cfs to the anticipated peak flow rate of 0.37 cfs from the Oak Springs Subdivision will be 0.41 cfs. This equates to 59% of the allowed 3/4 full flow capacity of 0.70 cfs for an 8-inch PVC pipe. This project will require the approval of the City Engineer and MDEQ. Annie Street Cottages—Wastewater Design Report Page 3 of 3 Appendix A Sewer Pipe Capacity Wastewater Design Report Sanitary Sewer Capacity 1 + ® 12+69 Project Description Friction Method Manning Formula Solve For Discharge Input Data .. _ Roughness Coefficient 0.013 Channel Slope 0.40 Normal Depth 6 in Diameter 8 in Results , Discharge 0.70 ft'/s Flow Area 0.28 ftT Wetted Perimeter 1.40 ft Top Width 0.58 ft Critical Depth 0.39 ft Percent Full 75.0 % Critical Slope 0.00773 ft/ft Velocity 2.48 ft/s Velocity Head 0.10 ft Specific Energy 0.60 ft Froude Number 0.63 Maximum Discharge 0.82 ft3/s Discharge Full 0.76 ft'/s Slope Full 0.00333 ft/ft Flow Type SubCritical GVF Input:Data Downstream Depth 0 in Length 0.00 ft Number Of Steps 0 'GVF Output Data Upstream Depth 0 in Profile Description Profile Headloss 0.00 ft Average End Depth Over Rise 0.00 Normal Depth Over Rise 75.00 % Downstream Velocity Infinity ft/s Upstream Velocity Infinity ftls Bentley Systems,Inc. Haestad Methods Solution Center FlowMaster [08.01.058.001 8/31/2007 4:58:26 PM 27 Siemons Company Drive Suite 200 W Watertown,CT 06795 USA +1-203-755-1666 Page 1 of 2 Sanitary a er Capacity 1 + - 12+69 GVF Output Data Normal Depth 6 in Critical Depth 0.39 ft Channel Slope 0.40 % Critical Slope 0.00773 ft/ft Bentley Systems,Inc. Haestad Methods Solution Center FlowMaster 108.01.058.00] 8/31/2007 4:58:26 PM 27 Siemons Company Drive Suite 200 W Watertown,CT 06795 USA +1-203-755-1666 Page 2 of 2 Sanitary Sewer Capcity 1 +69 - 1 + 7 Project Description Friction Method Manning Formula Solve For Discharge Input Data Roughness Coefficient 0.013 Channel Slope 0.40 Normal Depth 6 in Diameter 8 in Results Discharge 0.70 ft3/s Flow Area 0.28 ft2 Wetted Perimeter 1.40 ft Top Width 0.58 ft Critical Depth 0.39 ft Percent Full 75.0 % Critical Slope 0.00773 ft/ft Velocity 2.48 ft/s Velocity Head 0.10 ft Specific Energy 0.60 ft Froude Number 0.63 Maximum Discharge 0.82 ft3/s Discharge Full 0.76 ft3/s Slope Full 0.00333 ft/ft Flow Type SubCritical GVF In out Data:_ Downstream Depth 0 in Length 0.00 ft Number Of Steps 0 GVF Output Data Upstream Depth 0 in Profile Description Profile Headloss 0.00 ft Average End Depth Over Rise 0.00 % Normal Depth Over Rise 75.00 Downstream Velocity Infinity ft/s Upstream Velocity Infinity ft/s Bentley Systems,Inc. Haestad Methods Solution Center FlowMaster [08.01.058.00] 8/31/2007 5:00:30 PM 27 Siemons Company Drive Suite 200 W Watertown,CT 06795 USA +1-203-755-1666 Page 1 of 2 Sanitary a er Capcity 1 + - 13+97 GVF Output Data Normal Depth 6 in Critical Depth 0.39 ft Channel Slope 0.40 % Critical Slope 0.00773 ft/ft Bentley Systems,Inc. Haestad Methods Solution Center FlowMaster [08.01.058.00] 8/3112007 5:00:30 PM 27 Slemons Company Drive Suite 200 W Watertown,CT 06795 USA +1-203-755-1666 Page 2 of 2 Sanitary Sewer Capacity +97 - 15+27 Project Description Friction Method Manning Formula Salve For Discharge Input Data Roughness Coefficient 0.013 Channel Slope 0.50 Normal Depth 6 in Diameter 8 in Results :.: Discharge 0.78 ft'/s Flow Area 0.28 ftz Wetted Perimeter 1.40 ft Top Width 0.58 ft Critical Depth 0.42 ft Percent Full 75.0 % Critical Slope 0.00810 ft/ft Velocity 2.77 ft/s Velocity Head 0.12 ft Specific Energy 0.62 ft Froude Number 0.70 Maximum Discharge 0.92 ftl/s Discharge Full 0.85 ft3/s Slope Full 0.00416 ft/ft Flow Type SubCritical GVF Input Data Downstream Depth 0 in Length 0.00 ft Number Of Steps 0 GVF Output Data . Upstream Depth 0 in Profile Description Profile Headloss 0.00 ft Average End Depth Over Rise 0.00 % Normal Depth Over Rise 75.00 % Downstream Velocity Infinity fUs Upstream Velocity Infinity ft/s Bentley Systems,Inc. Haestad Methods Solution Center FlowMaster [08.01.058.00] 8/3112007 5:01:16 PM 27 Siemons Company Drive Suite 200 W Watertown,CT 06795 USA +1-203-755-1666 Page 1 of 2 Sanitary a er Capacity 1 + - 1 + 7 GVF Output Data Normal Depth 6 in Critical Depth 0.42 ft Channel Slope 0.50 % Critical Slope 0.00810 ft/ft Bentley Systems,Inc. Haestad Methods Solution Center FlowMaster [08.01.058.00] 8131/2007 5:01:16 PM 27 Slemons Company Drive Suite 200 W Watertown,CT 06795 USA +1-203-765-1666 Page 2 of 2 Sanitary Sewer Capacity 1 + - 2 +0 Project Description Friction Method Manning Formula Solve For Discharge Input Data Roughness Coefficient 0.013 Channel Slope 1.50 Normal Depth 6 in Diameter 8 in Results Discharge 1.35 ftg/s Flow Area 0.28 ftg Wetted Perimeter 1,40 ft Top Width 0.58 ft Critical Depth 0.55 ft Percent Full 75.0 % Critical Slope 0.01242 ft/ft Velocity 4.81 ft/s Velocity Head 0.36 ft Specific Energy 0.86 ft Froude Number 1.21 Maximum Discharge 1.59 ftg/s Discharge Full 1.48 ft3/s Slope Full 0.01247 Wit Flow Type SuperCritical GVF Input Data Downstream Depth 0 in Length 0.00 ft Number Of Steps 0 GVF Output Data Upstream Depth 0 in Profile Description Profile Headloss 0.00 ft Average End Depth Over Rise 0.00 Normal Depth Over Rise 75.00 Downstream Velocity Infinity ft/s Upstream Velocity Infinity ft/s Bentley Systems,Inc. Haestad Methods Solution Center FlowMaster [08.01.058.001 8/31/2007 5:04:34 PM 27 Siemons Company Drive Suite 200 W Watertown,CT 06795 USA +1-203-755-1666 Page 1 of 2 Sanitary Sewer Capacity 1 + - 20+00 GVF Output.Data Normal Depth 6 in Critical Depth 0.55 ft Channel Slope 1.50 % Critical Slope 0.01242 ft/ft Bentley Systems,Inc. Haestad Methods Solution Center FlowMaster [08.01.058.001 8/31/2007 5:04:34 PM 27 Siemons Company Drive Suite 200 W Watertown,CT 06795 USA +1-203-755-1666 Page 2 of 2 Sanitary Sewer Capacity 3 + +1 Project Description Friction Method Manning Formula Solve For Discharge Input Dafa Roughness Coefficient 0.013 Channel Slope 0.80 Normal Depth 6 in Diameter 8 in Results Discharge 0.99 ft3/s Flow Area 4.28 ft2 Wetted Perimeter 1.40 ft Top Width 0.58 ft Critical Depth 0.47 ft Percent Full 75.0 % Critical Slope 0.00926 ft/ft Velocity 3.51 ft/s Velocity Head 0.19 ft Specific Energy 0.69 ft Froude Number 0.89 Maximum Discharge 1.16 ft'/s Discharge Full 1.08 ft3/s Slope Full 0.00665 ft/ft Flow Type SubCritical GVF In ut Data Downstream Depth 0 in Length 0.00 ft Number Of Steps 0 GVF Output Data Upstream Depth 0 in Profile Description Profile Headloss 0.00 ft Average End Depth Over Rise 0.00 Normal Depth Over Rise 75.00 Downstream Velocity Infinity ft/s Upstream Velocity Infinity ft/s Bentley Systems,Inc. Haestad Methods Solution Center FlowMaster 108.01.058.001 8/31/2007 5:25 38 PM 27 Siemons Company Drive Suite 200 W Watertown,CT 06795 USA +1-203-755-1666 Page 1 of 2 Sanitary Sewer Capacity 3 + - +1 GVF Output Data Normal Depth 6 in Critical Depth 0.47 ft Channel Slope 0.80 % Critical Slope 0.00926 Wit Bentley Systems,Inc. Haestad Methods Solution Center FlowMaster [08.01.058.00] 8/3112007 6:25:38 PM 27 Siemons Company Drive Suite 200 W Watertown,CT 06795 USA +1-203-755-1666 Page 2 of 2 Sanitary Sewer Capacity +1 - 5+1 Project Description Friction Method Manning Formula Solve For Discharge Input Data,. Roughness Coefficient 0.013 Channel Slope 1.50 Normal Depth 6 in Diameter 8 in Results. Discharge 1.35 ft-1/s Flow Area 0.28 ft2 Wetted Perimeter 1.40 ft Top Width 0.58 ft Critical Depth 0.55 ft Percent Full 75.0 % Critical Slope 0.01242 ft/ft Velocity 4.81 ft/s Velocity Head 0.36 ft Specific Energy 0.86 ft Froude Number 1.21 Maximum Discharge 1.59 fts/s Discharge Full 1.48 ft9/s Slope Full 0.01247 ft/ft Flow Type SuperCritical GVF Input Data Downstream Depth 0 in Length 0.00 ft Number Of Steps 0 GVF Output Data Upstream Depth 0 in Profile Description Profile Headloss 0.00 ft Average End Depth Over Rise 0.00 Normal Depth Over Rise 75.00 Downstream Velocity Infinity ft/s Upstream Velocity Infinity ft/s Bentley Systems,Inc. Haestad Methods Solution Center FlowMaster [08.01.058.00] 8/31/2007 5:38:13 PM 27 Slemons Company Drive Suite 200 W Watertown,CT 06795 USA +1-203-755-1666 Page 1 of 2 Sanitary Sewer Capacity +1 - +1 GVF Output Data Normal Depth 6 in Critical Depth 0.55 ft Channel Slope 1.50 % Critical Slope 0.01242 ft/ft Bentley Systems,Inc. Haestad Methods Solution Center FlowMaster 108.01.058.001 8/31/2007 6:38:13 PM 27 Siemons Company Drive Suite 200 W Watertown,CT 06795 USA +1-203-755-1666 Page 2 of 2 Sanitary Sewer Capacity 4 + - 41+68 Project Description Friction Method Manning Formula Solve For Discharge Input Data Roughness Coefficient 0.013 Channel Slope 0.40 % Normal Depth 6 in Diameter 8 in Results.; Discharge 0.70 ft3/s Flow Area 0.28 ftz Wetted Perimeter 1.40 ft Top Width 0.58 ft Critical Depth 0.39 ft Percent Full 75.0 % Critical Slope 0.00773 ft/ft Velocity 2.48 ft/s Velocity Head 0.10 ft Specific Energy 0,60 ft Froude Number 0.63 Maximum Discharge 0.82 ft3/s Discharge Full 0.76 ft3/s Slope Full 0.00333 ft/ft Flow Type SubCritical GVF Input Data Downstream Depth 0 in Length 0.00 ft Number Of Steps 0 GVF Output Data Upstream Depth 0 in Profile Description Profile Headloss 0.00 ft Average End Depth Over Rise 0.00 % Normal Depth Over Rise 75.00 Downstream Velocity Infinity ft/s Upstream Velocity Infinity ft/s Bentley Systems,Inc. Haestad Methods Solution Center FlowMaster [08.01.058.00] 8/31/2007 5:40.17 PM 27 Slemons Company Drive Suite 200 W Watertown,CT 06795 USA +1-203.755-1666 Page 1 of 2 Sanitary a er Capacity 4 + ® 1+6 GVF'Output Data Normal Depth 6 in Critical Depth 0.39 ft Channel Slope 0.40 % Critical Slope 0.00773 ft/ft Bentley Systems,Inc. Haestad Methods Solution Center FlowMaster [08.01.058.001 8/3112007 6:40:17 PM 27 Siemons Company Drive Suite 200 W Watertown,CT 06795 USA +1-203-755.1666 Page 2 of 2