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HomeMy WebLinkAbout108-Water and Wastewater Report Water and Sewer Memo: for NELSON MEADOWS LOT 17 Gallatin County, Montana November, 2022 Prepared For: DGB Development, LLC Prepared By: Hyalite Engineers, PLLC Brett Megaard, PE 12/2/2022 Page 1 NELSON MEADOWS LOT 17 ENGINEER’S WATER AND SEWER MEMO Owner: DGB Development, LLC 244 Cirque Dr. Bozeman, MT 59718-9315 Introduction This report provides an estimate of the peak-hour sanitary sewer demand as well as the average and max day demands of domestic water usage for the proposed site development. The City of Bozeman Design Standards and Specifications (March 2004) was used as the primary guideline for this stormwater drainage design. General Design The proposed development of the site will contain 8 multifamily units, above commercial space. The eight residential units, as well as the bathrooms serving the commercial warehouse space, will have an 8” sewer main and 8” water main that will connect to the mains running down Royal Wolf Road. From these mains, they will share a new 1.5” copper water service and 6” SCH 40 PVC sewer service. The sewer services will be installed at a minimum slope of ¼-inch per foot. Cleanouts will be provided at each bend as well as at the exterior of the building. The water service will also run off of the 8” water main that runs down Royal Wolf Road. Water services are to be 4” for the domestic supply for a fire sprinkler system, on top of the fixture count demand as shown in the included Fixture Count chart. Sewer Demands for Building 1 (West) Assuming an average daily flow of 2.17 people per dwelling with 64.4-gallons per capita per day: (2.17 people per dwelling) X (4 dwellings) = 8.68 people (8.68 people) X (64.4 gallons per person per day) = 559 gallons per day Using a peaking factor of 4.43 calculated from equation 10-1 from DEQ Circular 2: (559 gpd) X 4.43 = 2,576 gpd (1.72 gallons per minute) Infiltration rate = 150 gal / ac / day x (0.97 ac) = 146 gpd (0.10 gallons per minute) Total Sewer Flow = 2,576 gpd + 146 gpd = 2,722 gpd (1.82 gallons per minute) Water Demands for Building 1 (West) Assuming 2.17 people per dwelling with an average daily usage of 170-gallons per person: (2.17 people per dwelling) X (4 dwellings) = 8.68 people (8.68 people) X (170 gallons per day) = 1,476 gallons per day Using a maximum day to average day ratio of 2.3:1 from City of Bozeman Design Standards: Page 2 (1476 gpd) X 2.3 = 3,394 gallons per day (2.36 gallons per minute) Fire Flow Demand = 990 sf * 0.20 gpm/sf * 1.3 (over-flow factor) = 260 gpm Total Demand = 262.36 gpm Sewer Demands for Building 2 (East) Assuming an average daily flow of 2.17 people per dwelling with 64.4-gallons per capita per day: (2.17 people per dwelling) X (4 dwellings) = 8.68 people (8.68 people) X (64.4 gallons per person per day) = 559 gallons per day Using a peaking factor of 4.43 calculated from equation 10-1 from DEQ Circular 2: (559 gpd) X 4.43 = 2,576 gpd (1.72 gallons per minute) Infiltration rate = 150 gal / ac / day x (0.97 ac) = 146 gpd (0.10 gallons per minute) Total Sewer Flow = 2,576 gpd + 146 gpd = 2,722 gpd (1.82 gallons per minute) Water Demands for Building 2 (East) Assuming 2.17 people per dwelling with an average daily usage of 170-gallons per person: (2.17 people per dwelling) X (4 dwellings) = 8.68 people (8.68 people) X (170 gallons per day) = 1,476 gallons per day Using a maximum day to average day ratio of 2.3:1 from City of Bozeman Design Standards: (1476 gpd) X 2.3 = 3,394 gallons per day (2.36 gallons per minute) Fire Flow Demand = 990 sf * 0.20 gpm/sf * 1.3 (over-flow factor) = 260 gpm Total Demand = 262.36 gpm Appendix A – Residential Water Service N E L S O N M E A D O W S L O T 1 7 N O V E M B E R 2 0 2 2 A P P E N D I X APPENDIX A RESIDENTIAL WATER SERVICE