Loading...
HomeMy WebLinkAboutTHE NORTHERN_Utility Report._20250411Water and Sewer Design Report for The Northern Planning Application #24595 Bozeman, Montana April 11, 2025 Prepared For: Drake Building & Development 29785 Max Avenue, #1050 Bozeman, MT 59718 406-595-1782 Contact: Cole Nelson Prepared By: Incline Civil LLC 101 East Loucks Street, #300 Sheridan, WY 82801 970-227-0714 Contact: Ryan C. Meisel, PE 101 E. Loucks Street, #300 Sheridan, WY 82801 970-227-0714 Introduction: This water and sewer design report for the proposed development, The Northern, has been prepared to present the fire flow demand requirements, domestic water flow demand requirements, and the sewer peak flow contributions to the surrounding public infrastructure utilities. This report will also present the capacity of the proposed sanitary sewer service line, the proposed sanitary sewer main, and the existing fire flow measurements at the existing fire hydrant adjacent to the site. All demand and flows calculations have been calculated in accordance with the City of Bozeman Design and Construction Standards (Revised October 2024). The proposed development is located at 621 W. Mendenhall Street, at the corner of N. 7th Avenue and W. Mendenhall Street in Bozeman, Montana. The site contains of 0.46 acres and will consist of a new, mixed use 7-story multifamily apartment building with structured parking. The proposed fire and water service lines will connect to the existing 8” water main in W. Mendenhall Street and the sewer service will connect to a proposed 8” sanitary sewer main in W. Mendenhall Street that will be improved as part of the development. The existing 6” sanitary sewer main adjacent to the site in W. Mendenhall Street has been determined to be insufficient to support the development during the concept submittal. As a result, an 8” sewer main replacement will be required in W. Mendenhall Street from N. 7th Avenue east to N. 5th Avenue. Water Design Report: The proposed water improvements consist of a 6” diameter fire service line and a 4” diameter domestic water service line that will extend from the fire room located on the south face of the proposed building to the existing 8” water main in W. Mendenhall Street. A fire department connection (FDC) will be located on the south face of the proposed building within 100’ of the existing fire hydrant located at the corner of N. 7th Avenue and W. Mendenhall Street. It should be noted that the existing fire hydrant will need to be removed and reset on the existing fire hydrant lateral in the proposed boulevard adjacent to W. Mendenhall Street. The water demands have been calculated in accordance with Section 4.2.4 of the City of Bozeman Design and Construction Standards. The domestic water average day demand was determined to be 24,022 GPD (16.7 GPM) and the maximum day demand was determined to be 55,250 GPD (38.4 GPM) using a peaking factor of 2.30 per Table 4.2.3. The peak hour demand was determined to be 50.05 GPM using a peaking factor of 3.0 per Table 4.2.3. Water demand calculations can be found in Appendix A. 101 E. Loucks Street, #300 Sheridan, WY 82801 970-227-0714 The required fire flow was determined for the proposed building with construction types of I-A and I-B based on the total square footage of the three largest successive floors per Section B104.3 in the 2021 IFC Appendix B. The area of the three largest successive floors was calculated to be 51,204 square feet, resulting in a fire flow of 2,500 GPM per Table B105.1. Because the building will be fully sprinklered, the fire flow can be reduced to 25% of this value resulting in a fire flow of 625 GPM per Table B105.2. A minimum fire flow value of 1,500 GPM has been used per note b in Table B105.2. The number of hydrants required to provide the minimum fire flow will be 1 with a flow of 1,750 GPM per IFC Appendix C, Table C102.1. Fire hydrant flow tests were requested for hydrant #2748 adjacent to the site and a resulting flow of 1,800 GPM at 114.07 psi was measured, which demonstrates that the fire flow requirements can be met by existing fire hydrant #2748. Hydrant flow data can be found in Appendix B. The water demand analysis performed for the proposed site has resulted in a fire flow for the requirement of 1,750 GPM along with the peak hour domestic demand of 50.05 GPM, which can be combined for a resulting total demand of approximately 1,800 GPM. Based on this total demand and the flow results from hydrant #2748 adjacent to the site, it has been determined that the existing water main and fire hydrant will be sufficient to meet all water demands for the proposed development by providing 1,800 GPM at 114.07 psi, which exceeds the minimum residual pressure of 20 psi. Sewer Design Report: The proposed sewer improvements consist of a 8” diameter sewer service line that will extend from the proposed building along the south face to the proposed 8” sewer main in W. Mendenhall Street. The sewer demands have been calculated in accordance with Section 5.2.4 of the City of Bozeman Design and Construction Standards. The average daily sanitary flow was determined to be 11,459 GPD (8.0 GPM) and the maximum flow was determined to be 47,741 GPD (33.2 GPM) with a peak hour factor of 4.17. Sanitary sewer demand calculations can be found in Appendix A. A pipe capacity analysis has been performed to determine that a 8” sewer service sloped at 1.04% has a capacity of 1.57 cfs or 705.95 GPM which is far above the calculated flows for the proposed development (33.2 GPM), therefore the proposed sewer service will adequately convey building flows to the 8” sanitary sewer main in W. Mendenhall Street. A pipe capacity 101 E. Loucks Street, #300 Sheridan, WY 82801 970-227-0714 analysis was also performed for the proposed sanitary sewer main in W. Mendenhall Street to determine that the 8” sewer main sloped at 0.5% has a capacity of 1.09 cfs or 489.19 GPM. Hydroflow Express outputs that demonstrate the sanitary sewer line capacities can be found in Appendix A. Conclusion: As demonstrated above, the proposed 6” fire service line and 4” domestic service line will adequately serve the mixed use 7-story multifamily apartment building with structured parking that is proposed for the site at 621 W. Mendenhall Street in Bozeman, Montana. The proposed sanitary sewer flow information above also provides flow information that can be input into the City of Bozeman sanitary sewer model to verify that the proposed flows can be adequately conveyed in the surrounding sanitary sewer network. 101 E. Loucks Street, #300 Sheridan, WY 82801 970-227-0714 APPENDIX A WATER AND SEWER DEMAND CALCULATIONS Project: The Northern Project #: 2024017 Date: 3/28/2025 Calculated By: RCM Water Average Daily Demand Calculations Residential Units = 81 + 1(retail) Density = 2.17 ppl/dwelling unit Per Capita Flow Rate = 135.0 GPD/ppl QAVG = (82 units)(2.17 ppl/unit)(135.0 GPD/ppl) QAVG = 24,022 GPD = 16.68 GPM Water Maximum Daily Demand Calculations Peaking Factor = 2.30 (per COB table 4.2.3) Maximum Day Demand (MDD) = (Peaking Factor)(Q AVG) MDD = (2.30)(24,022 GPD) MDD = 55,250 GPD = 38.37 GPM Water Peak Hour Demand Calculations Peaking Factor = 3.00 (per COB table 4.2.3) Peak Hour Demand (PHD) = (Peaking Factor)(QAVG) PHD = (3.00)(16.68 GPM) PHD = 50.05 GPM Project: The Northern Project #: 2024017 Date: 3/28/2025 Calculated By: RCM Sanitary Sewer Peak Flow Calculations Residential Units = 81 + 1(retail) Density = 2.17 ppl/dwelling unit Per Capita Flow Rate = 64.4 GPD/ppl QAVG = (82 units)(2.17 ppl/unit)(64.4 GPD/ppl) QAVG = 11,459 GPD = 7.96 GPM = 0.01773 CFS Infiltration/Inflow = (150 gal/acre*day)(0.465 acre) Infiltration/Inflow =69.7 GPD = 0.00011 CFS P = Population/thousands = (2.17*82)/1000 = 0.1779 Peak Flow Factor = (18+P1/2)/(4+P1/2) = (18+0.42)/(4+0.42) Peak Flow Factor = 4.17 QMAX = (Peak Flow Factor)(QAVG) QMAX = (4.17)(11,459) QMAX = 47,741 GPD = 33.15 GPM Channel Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Friday, Mar 28 2025 <Name> Circular Diameter (ft) = 0.67 Invert Elev (ft) = 4813.03 Slope (%) = 1.04 N-Value = 0.011 Calculations Compute by: Q vs Depth No. Increments = 10 Highlighted Depth (ft) = 0.60 Q (cfs) = 1.573 Area (sqft) = 0.33 Velocity (ft/s) = 4.70 Wetted Perim (ft) = 1.68 Crit Depth, Yc (ft) = 0.59 Top Width (ft) = 0.40 EGL (ft) = 0.95 0 1 Elev (ft)Section 4812.75 4813.00 4813.25 4813.50 4813.75 4814.00 Reach (ft) Channel Report Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Wednesday, Apr 9 2025 <Name> Circular Diameter (ft) = 0.67 Invert Elev (ft) = 4813.03 Slope (%) = 0.50 N-Value = 0.011 Calculations Compute by: Q vs Depth No. Increments = 10 Highlighted Depth (ft) = 0.60 Q (cfs) = 1.090 Area (sqft) = 0.33 Velocity (ft/s) = 3.26 Wetted Perim (ft) = 1.68 Crit Depth, Yc (ft) = 0.50 Top Width (ft) = 0.40 EGL (ft) = 0.77 0 1 Elev (ft)Section 4812.75 4813.00 4813.25 4813.50 4813.75 4814.00 Reach (ft) 101 E. Loucks Street, #300 Sheridan, WY 82801 970-227-0714 APPENDIX B FIRE FLOW MEASUREMENTS FOR HYDRANT #2748 GIS Hydrant # Available Flow (gpm) Residual Pressure (psi)2748 0 122.84 200 122.36 400 121.83 600 121.14 800 120.3 1,000.00 119.32 1,200.00 118.2 1,400.00 116.96 1,600.00 115.58 1,800.00 114.07 2,000.00 112.43 2,200.00 110.67 2,400.00 108.78 2,600.00 106.77 2,800.00 104.63 3,000.00 102.37 3,200.00 100 3,400.00 97.5 3,600.00 94.89 3,800.00 92.16 4,000.00 89.31 4,200.00 86.36 4,400.00 83.28 4,600.00 80.1 4,800.00 76.8 5,000.00 73.39 5,200.00 69.86 5,400.00 66.23 5,600.00 62.49 5,800.00 58.65 6,000.00 54.69 6,200.00 50.63 6,400.00 46.45 6,600.00 42.14 6,800.00 37.73 7,000.00 33.2 7,200.00 28.58 7,400.00 23.85 7,600.00 19.01 7,800.00 14.06 8,000.00 9.01 8,200.00 3.86 8,345.91 0.03 Hydrant Curve 0 20 40 60 80 100 120 140 0 1000 2000 3000 4000 5000 6000 7000 8000 9000Residual Pressure (psi)Available Flow (gpm) Hydrant Curve 2748 Data Disclaimer: Water distribution information is calculated using hydraulic modeling software and is subject to variation. Actual field conditions may vary. This information is provided to the requestor for evaluation purposes only, without warranty of any kind, including, but not limited to any expressed or implied warranty arising by contract, stature, or law. In no event regardless of cause, shall the City be liable for any direct, indirect, special, punitive or consequential damages of any kind whether such damages arise under contract, tort, strict liability or inequity.