The URL can be used to link to this page

Home My WebLink About5.0_210847_Water and Sewer Demands (Signed) DESIGN REPORT WATER AND SANITARY SEWER DEMAND CALCULATIONS LOT 109 BLOCK 2, NELSON MEADOWS SUBDIVISION Prepared for: OH MY GORD, LLC 1283 North 14th Avenue. Suite 103 Bozeman, MT 59715 Prepared by: Engineering and Surveying Inc. 1091 Stoneridge Drive • Bozeman, MT 59718 Phone (406] 587-1115 • Fax(406) 587-976B www.chengineers.com • info @chengineers.cam ! `� 1. April 2022 Revised November 2022 '" C&H Project No. 210847 INTRODUCTION The Big Sky Benefits Solutions Site Plan project proposes to develop Lot 10 of Block 2 located in the Nelson Meadows Subdivision. The proposed layout consists of one single story office building, parking lot for the development, and related stormwater and landscaping areas. The property is located within the City of Bozeman limits and is currently zoned M-1. The property is fronted on the east side by Nelson Road. An existing water main is located within Nelson Road and an existing sanitary sewer main is located to the west of the property in Lot 15 of Block 2 in the Nelson Meadows Subdivision located within the shared 30' public utility and access easement shown on plat J-680. Individual water, fire, and sanitary sewer services will connect to the proposed buildings as shown on civil sheet C3.0 (utility plan). Water Distribution System Demands The design approach taken to determine the water demand for the proposed office building was evaluating water demand for similar office buildings within Bozeman. This approach was used since there is no available data on water usage for commercial development. The buildings used were C&H Engineering and Surveying as well as The Dames Building and the water demand over the course of five months. October 2018 through February 2019 were chosen to be relevant data since the meter readings are not impacted by seasonal irrigation and pre COVID-19 employment impacts. C&H Usage History Daines Building Usage Month Days Usage(HCF) Month Days Usage(HCF) November2019 29 13.1000 November2019 29 7.7500 December2019 32 11.5500 December2019 32 8.8500 January 2020 30 5.0000 January 2020 30 7.3500 February 2020 29 6.6000 February 2020 29 8.3000 March 2020 32 6.1500 March 2020 32 8.5000 Total: 152 42.4000 Total: 152 40.7500 2789 HCF/Day 0.2681 HCF/Day Average: Average: FGal/Day 200.5468 Gal/Day Building Water Usage Summary Building Type Gross Area[SF] Usage Rate[Gal./Day/SF] Units C&H(Office) 5,500 0.0379 1 HCF = 100.0000 Ft' Daines Building 1 Ft = 2.832E-02 m3 (Office) 10,000 0.0201 1 Gal. = 3.785E-03 m3 Average: 0.0290 1 Ft = 7.4805 Gal. 1 HCF = 748.0520 1 Gal. Water Usage Analysis 1 kcre-Footj1 1233.489 m3 Building Type Gross Area[SF] Usage Rate[Gal./Day] Gal UsageTotai HCF] r Gall Big Sky Benefits g Av = L *748.0520 L-1H 5,118 148.4071 Day DaysTotai DayJCF (BuildingA Phase Gal r Gal�Gross ay Avg. DayAvg. SF Area[Sf] Based on the figures above, the daily usage rate for the proposed office building is estimated at 148.4 gpd. Sanitary Sewer Design Load The peaking factor for the design area is determined using DEQ Circular 4, Table 3.1-1. With proposed building A anticipated to be used as office building, a generation rate of 13.0 gal/day/employee will be used for system design. Peaking Factor= 3.87* gal Assumed Infiltration = 150 day = (150 gal) (1.88 acre) = 282 acr day The peak flow rate is calculated by multiplying the DEQ Circular 4, table 3.1-1 generation rate of 13 gallons per employee per day by the population, multiplying by the peaking factor, and adding the infiltration rate: gal Peak Flow Rate = 13 employee * 30 employee" * 3.87 + 282 day 3 Peak Flow Rate = 1791.30 dal = 1.244 gal min tt= 0.0033 s day sec *Peaking factor of 3.87 provided by the sewer design report done by Morrison-Maierle for Nelson Meadows Subdivision in 2018. During the design of the subdivision, a design flow of 187 gal/minute was determined for the total 69.47 acres encompassing the Nelson Meadows Subdivision. This results in a proportionate value of 2.69 gal/minute/acre or 0.0060 ft3/second/acre allocating a total of 0.0113 ft3/sec for lot 10 (1.88 acres). A copy of this report is provided in Appendix A of this report. 8-inch PVC Pipe @ 75%Capacity Pipe Diameter= 8 in Qf.u= 0.7643 cfs Manning's n= 0.013 (for PVC) Qo.75= 0.5732 cfs Min. Slope = 0.004 ft/ft Peak Flow: Qpeak= 0.0033 cfs Area = 0.3491 ftz Perimeter= 2.0944 ft Hydraulic Radius= 0.1667 ft **The number of employees is based off an estimate of 175 SF/Employee SF SF/Employee Employee BuildingA 5118 175 30 In summary, the proposed 5,118 sf office building generates a third less than that allocated to the parcel during the design of the subdivision's sanitary sewer infrastructure. This also indicates that the proposed 8-inch sanitary sewer main is more than adequate to handle the projected peak flow. G:\C&H\21\210847\Design Reports\Sewer\210847-Water And Sewer Demands.Docx APPENDIX A MORRISON-MAIERLE SANITARY SEWER DESIGN REPORT NELSON MEADOWS SUBDIVISION (2018) In this case, the MDT hydrant is used to check model output while using the Springhill Road and Campbell Road hydrant as the supply for the model.Reasonable results were observed from the model when equal flow is applied to the node on the MDT property as a check. Table 5: Water Model Inputs-3 Point Pum 9 and Reservoir Connection Condition Flow m Head ft Head(psi) Springhill Road and Shutoff 0 291 126 Campbell Road Design 1,572 268 116 Intersection Max.Operating' 5,636 46 20 'Calculated Value Demand on the new water distribution system was placed at the northern end of each of the project at the furthest point from the existing City distribution system. Fire flows of 1,600 gpm were applied at the furthest hydrant location in addition to maximum day demands using the single connection near MDT. When the future connection from Davis Lane is complete, available fire flow is expected increase as predicted in Figure 9-9 and as recommended for M-1 zoning in Table 5.7 of the Water Facility Plan. Distributions system modeling results indicate that the proposed water mains will be capable of providing the needed flows for the project. Information from the water modeling is provided following this report. 3.0 Wastewater System Wastewater Generation The wastewater generation for the proposed development includes sewer services for M-1 Zoning designation includes uses outlined in the UDO Sec.38.300.120.The City Design Standards and Specifications Policy document(Table V-1 Page 49) lists wastewater flow rate based on zoning classification and the peak hour factor is calculated based on the City Design Standards and Specification Policy(Page 48). The final addition to projected wastewater generation is infiltration/inflow(I/I)which is 150 gpd/acre per the City Design Standards and Specifications Policy(Page 48). Table 6: Wastewater Projections Average Day Peak Hour Inflow/ Design Flow Zoning Acreage Flow(gpd)' Flow(gpm)2 Infiltration (gpm)4 M-1 69.47 66,691 180 10,421 187 'Design Standards and Specifications Policy(M-1 is 960 gpd/acre) Equivalent Population of 749 at 89 gped.Peak hour factor of 3.87. 3 Design Standards and Specifications Policy(150 gpd/acre) 4 Sum of Peak Hour Flow and I/1 • Average daily flow is anticipated to be 66,691 gpd or 46 gpm. • The peak hour flows are calculated to be 180 gpm based on a factor of 3.87. • Sum of peak hour flow and I/I is 187 gpm Nelson Meadows will utilize City wastewater capacity for 66,691 gpd of average day flow plus the potential for 10,421 gpd of Ul. Sewer collection mains,lift station,and forcemain infrastructure will be sized to handle the peak flow requirement of 187 gpm for the development. Sewer Improvements N:\2286\009\04 Design\Reports\Water and Sewer\Water&Sewer Report.docx 4