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HomeMy WebLinkAbout007SanitaryDemand                                                                                                                                                                                               MEMO 32 Discovery Drive                Bozeman, MT  59718                (406) 582‐0221                 Fax (406) 582‐5770  Project Name: Nikles Business Park - Site Plan Project Number: AESI 21-076 Date: November 23, 2021 Re: Sanitary Sewer Demand MEMO DETAILS: The purpose of this memo is to outline the estimated average daily and peak hour sanitary sewer demand for the commercial site development of Lot 3A of McChesney Industrial Park Subdivision. The demand is estimated based on guidelines provided in the Montana Department of Environmental Quality (MDEQ) Circular 4 and the City of Bozeman Design Standards and Specifications. An existing 4” PVC sanitary sewer service will be used to serve the phase 1 structure. A new sewer service would be provided for the future/phase 2 structure via the existing main located in Evergreen drive. We anticipate extending the services for the phase 2 structure as part of the phase 1 improvements to avoid cutting the parking improvements associated with phase 1. An average wastewater flow rate of 13 gallons per day per employee was assumed as outlined in MDEQ-Circular 4 Table 3.1 “Typical Wastewater Flows from Commercial, Industrial, and Other Nonresidential Sources”. An infiltration rate of 150 gal/acre/day was added to the flow demand calculations per the COB Design Standards and Specifications. Please see the attached calculations for additional information. A summary is provided below. Phase 1  Number of employees = 15  Gross area of site = 0.99 acres  Infiltration rate = 150 gpd (0.10 gpm)  Average day demand + infiltration = 345 gpd (0.24 gal/min)  Peaking factor (P=0.015) = 4.40  Peak hour demand = 1,517 gpd (1.05 gpm) 11/23/2021 Allied Engineering Services, Inc. Memo Page 2 Phase 2  Number of employees assumed (TBD) = 20  Gross area of site = 0.99 acres  Infiltration rate = 150 gpd (0.10 gpm)  Average day demand + infiltration = 410 gpd (0.28 gpm)  Peaking factor (P=0.02) = 4.38  Peak hour demand = 1,796 gpd (1.25 gpm) Please contact Madeline Good and/or Rory Romey at 406-582-0221 or mgood@alliedengineering.com; rromey@alliedengineering.com with any questions or if additional information is required.