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HomeMy WebLinkAbout010 - NPWH - Water Sewer Demands NORTH PARK WYNDHAM HOTEL WATER AND SANITARY SEWER DEMANDS REPORT Bozeman, Montana Prepared for: City of Bozeman Planning & Engineering Depts. 20 East Olive St. Suite 202 Bozeman, MT 59715 Prepared by: DJ&A, P.C. 220 W. Lamme Street Suite 1D Bozeman, MT 59715 September 11, 2023 N NPSSROFE OI NOM AT A AL E EEN GINRMICHAEL T. RUSSELL No. 59647PE TOC-1 Water and Sanitary Sewer Demands Report Table of Contents 1. General ........................................................................................................................................... 1 2. Existing Site Conditions .................................................................................................................. 1 3. Water and Sanitary Sewer Demands ............................................................................................. 2 3.1 Water Demand Calculations ................................................................................................... 2 3.2 Sanitary Sewer Demand Calculations .................................................................................... 3 4. Summary ........................................................................................................................................ 4 References ............................................................................................................................................. 5 List of Figures Figure 1: Proposed Project Site Location .............................................................................................. 1 List of Tables Table 1: Water Demand Summary (ADD, MDD, PHD) ......................................................................... 2 Table 2: Water Demand Summary (UPC Appendix A) ......................................................................... 3 Table 3: Peak Hour Sanitary Sewer Demand Summary ....................................................................... 3 List of Attachments Appendix A – City of Bozeman Correspondence – Average Water Usage Rate Water and Sanitary Sewer Demands Report North Park Wyndham Hotel, Bozeman MT Page 1 SEPTEMBER 2023 Water and Sanitary Sewer Demands Report 1. General This report provides estimated water and sewer demands for the proposed North Park Wyndham Hotel site, which includes a 4-story building with 124 rooms. There will also be an on-site irrigation system. The 2.21-acre site is located in the northwest corner of the intersection of Mandeville Drive and Wheat Drive in Bozeman, Montana. The property is zoned M-1. Figure 1: Proposed Project Site Location 2. Existing Site Conditions The existing site is currently undeveloped. The site generally drains southwest to northeast with gentle slopes of approximately 1-2%. Groundwater monitoring was completed by TD&H Engineering late Spring/early Summer following a very wet spring and a year with a strong snowpack. Groundwater was found at depths of approximately 12-13 feet deep, which is anticipated to represent pretty closely to the peak groundwater for the site. Water and sewer service utilities are estimated to be constructed approximately 6-7 feet deep, so utility excavations and installations are not anticipated to be close to groundwater. The proposed hotel is anticipated to be served by the City of Bozeman’s public water and sanitary sewer systems. A 12” sanitary sewer main and 10” water main are located along the newly built Water and Sanitary Sewer Demands Report North Park Wyndham Hotel, Bozeman MT Page 2 SEPTEMBER 2023 Wheat Drive, located directly adjacent to the site to the east. An 8” water main and 8” sewer main were stubbed out from the mains along Wheat Drive and extend onto the property with a public utility easement. The site will require sanitary sewer, potable water, and fire suppression service connections into the City’s water and sewer mains. This report focuses on the domestic water (including irrigation) and sanitary sewer demands, as fire suppression flows will be supplied by a separate fire suppression lateral to be designed as part of a future infrastructure submittal. 3. Water and Sanitary Sewer Demands 3.1 Water Demand Calculations The City’s Engineering/Utilities Department provided estimated domestic water use rates for hotels. The City provided a conservative average daily water use rate of 64 gpd/room (see Appendix A for email correspondence). This equates to an average daily water use rate of 7,936 gpd, or 5.5 gpm, for domestic water use of the proposed 124-room Wyndham Hotel. The hotel site will also have an irrigation system connected to the domestic water service line. The landscape team estimates an annual irrigation demand of 55,152 gallons. Assuming a 16-week watering season, the average daily demand for the irrigation system is 1,149 gpd, or 0.8 gpm. The design average daily demand for the water service line considering domestic and irrigation demands is approximately 6.3 gpm. Peaking factors from Section 5 of the Bozeman DSSP were used to account for maximum day and peak hour water use demands. The design maximum day demand is 14.5 gpm assuming a peaking factor of 2.3. The design peak hour demand is 18.9 gpm assuming a peaking factor of 3. Table 1 below summarizes the domestic water service design demands based on the Bozeman DSSP peaking factors. Table 1: Water Demand Summary (ADD, MDD, PHD) Water Service Design Demands ADD Peak Factor (From Bozeman DSSP) Demand (gpm) Design Average Day Demand (ADD) 1 6.3 (5.5 gpm domestic + 0.8 gpm irrigation) Design Maximum Day Demand (MDD) 2.3 14.5 Design Peak Hourly Demand (PHD) 3 18.9 Water demand calculations above are based on average daily demand estimations with peaking factors provided in Section 5 of the Bozeman DSSP. The water service line for the proposed hotel is sized based on fixture units calculations. The mechanical engineer for this commercial development project (Three Rivers Engineering) provided the domestic water service demand in accordance with Uniform Plumbing Code (UPC) Appendix A and City of Bozeman fixture unit calculations. The mechanical engineer calculated the estimated peak domestic demand is approximately 216.5 gpm based on the number of water fixture units. Continuous supply demands for the irrigation and commercial laundry extractors were also considered at peak demands of 30 gpm and 37 gpm, respectively. This provides a peak water service demand of 283.5 gpm. Water and Sanitary Sewer Demands Report North Park Wyndham Hotel, Bozeman MT Page 3 SEPTEMBER 2023 Table 2: Water Demand Summary (UPC Appendix A) Water Service Design Demands Demand (gpm) Fixture Units Peak Demand 216.5 Irrigation Peak Demand 30 Commercial Laundry Extractors Peak Demand 37 Total 283.5 To ensure peak velocity is less than 10 feet per second at a peak instantaneous flow of 283.5 gpm, the mechanical engineer is proposing a 4-inch water service line to meet the water service demands. The pipe material will be ductile iron. The hotel’s fire suppression demand will be supplied by a separate fire service lateral connected directly to the City 8” water main, so needed fire flows were not considered in these water demand calculations. The fire service lateral is anticipated to be a 4” service line. This 4” fire service lateral will be further designed as part of the future Infrastructure Plan submittal following the Site Plan stage. 3.2 Sanitary Sewer Demand Calculations City of Bozeman Design Standards were used to calculate the sanitary sewer demands, per the Bozeman DSSP. An average demand of 64 gpd/room provided by the City was used for sanitary sewer demand calculations, similar to the water demand calculations, which equates to a design average flow of 5.5 gpm for a 124-room hotel. The peak hour flow equation (DSSP page 48) and an equivalent population of 254 people was used to calculate a peak hour factor of 4.1. The peak hour domestic demand is 22.6 gpm. Infiltration flows must also be considered at 150 gallons/acre/day. The 2.2-acre site equates to an infiltration rate of approximately 0.23 gpm. A peak domestic demand of 22.6 gpm and an infiltration rate of 0.23 gpm equates to a sanitary sewer demand of approximately 22.9 gpm for the proposed hotel. A summary of the sanitary sewer demand calculations for the proposed hotel is provided in Table 3 below. Table 3: Peak Hour Sanitary Sewer Demand Summary Parameter Value Average Daily Domestic Demand 5.5 gpm Peak Factor (PF) for Peak Hourly Flow 4.1 Peak Hourly Domestic Demand 22.6 gpm Infiltration Rate (2.2 acres) 0.23 gpm Total Sanitary Sewer Demand 22.9 gpm Water and Sanitary Sewer Demands Report North Park Wyndham Hotel, Bozeman MT Page 4 SEPTEMBER 2023 Similar to the water service line described in Section 3.1, the sewer service lateral will be sized per the mechanical engineer’s drainage fixture calculations based on the UPC. The hotel will be served by an 8-inch PVC SDR 35 sewer lateral that connects to an existing 8-inch stub upstream of the 10- inch sewer main on Wheat Drive. The mechanical engineer sized the 8-inch sewer service to the building based on Chapter 7 of the UPC, which uses drainage fixture units and does not necessarily equate to a gpm. If we were to assume water in equals water out, the peak sewer demand would be calculated as 253.5 gpm (216.5 gpm for the number of fixture units and 37 gpm for the commercial laundry extractors). 4. Summary A 124-room hotel with an on-site irrigation system is being proposed at the northwest corner of the Mandeville Road and Wheat Drive intersection and will connect to the City of Bozeman’s public water and sanitary sewer systems. The hotel’s irrigation system and domestic demands will be supplied by the 4-inch domestic water service, which will be supplied by an 8-inch City water main. The hotel’s sanitary sewer demands will be supplied by an 8-inch lateral connected to the City’s 10-inch sewer on Wheat Drive. The estimated peak water demand based on the mechanical engineer’s fixture unit and continuous supply demands calculation is 283.5 gpm. Water and Sanitary Sewer Demands Report North Park Wyndham Hotel, Bozeman MT Page 5 SEPTEMBER 2023 References · City of Bozeman. “Design Standards and Specifications Policy.” City of Bozeman Engineering Division. 2004. Web accessed 2023. Water and Sanitary Sewer Demands Report North Park Wyndham Hotel, Bozeman MT Attachment A — City of Bozeman Correspondence Average Water Usage Rate 1 Bryana Zuiderweg From:Griffin Nielsen <GNielsen@BOZEMAN.NET> Sent:Monday, March 13, 2023 1:26 PM To:Bryana Zuiderweg Subject:RE: CILWR - North Park Wyndham Hotel Development Attachments:ATT00001.txt; ATT00002.htm Hi Bryana, I’ll be performing the detailed CILWR review with the site plan application, but to give you an idea of what to expect for the CILWR fee below is a preliminary determination. The demand rate may be adjusted depending on the hotel amenities (i.e. pool, restaurant, etc.) but 64gpd/room generally is conservative. Let me know if you have any questions. Thanks, City of Bozeman MT Griffin Nielsen, PE| Engineering/Utilities Department D:406.582.2279 C:406.595.1598 gnielsen@bozeman.net From: Bryana Zuiderweg <Bryana.Zuiderweg@djanda.com> Sent: Friday, March 10, 2023 11:44 AM To: Griffin Nielsen <GNielsen@BOZEMAN.NET> CAUTION: This email originated from outside the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe.