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Home My WebLink About96 - Design Report - University Apartments - Water, Sewer GA S T ON ENGINEERING SURVEYING / SOILS TESTING RECEIVED JUN 2 8 19� ' JU` ENGINEERS'REPORT for WATER & SEWER IMPROVEMENTS for the UNI PER SI T Y APAR TMENT S BOZEM41v, MONTANA February, 1996 W.O. # 94-525 CONSULTING ENGINEERS & LAND SURVEYORS®®I P.O.Box 861 •211 Haggerty Lane-Bozeman,MT 59715•(406)586-0588•fax(406)586.0589 ENGINEERS' REPORT for WA TER & SEWER IMPRO VEMENTS for the UNI VERSITYAPARTMENTS POZEMAN, MONTANA February, 1996 W.O. # 94 525 ENGINEERS' REPORT UNIVERSITY APARTMENTS Bozeman, Montana 1. INTRODUCTION 1.1 Purpose The purpose of this report is to present factual data, process description, sizing, controlling assumptions, and considerations for the extension of the City of Bozeman water and sewer systems to serve the proposed University Apartments Development. 1.2 Location The proposed University Apartments Development is located on Tract A of C.O.S. 573, 1800 West Kagy Boulevard, City of Bozeman, Gallatin County, Montana. 2. SCOPE 2.1 Sewer The method of sewage disposal will be via a 8"PVC sewer main installed within the development. The proposed 8" main will discharge to the existing City of Bozeman sewer main on Lincoln Road. The existing sewer main on Lincoln Road is part of the City of Bozeman sewage collection system and is currently maintained by the City of Bozeman. This proposed sewer system will be comprised of 7 new manholes, approximately 1200 LF 8" SDR35 PVC sewer main. 2.2 Water Water will be provided via a looped main which will connect to existing water mains maintained by the City of Bozeman. The loop will require connection to the existing 12" main on Lincoln Ave. and connection to the existing 8" main to the south of Remington Way. A 6" main will be installed within the development to provide water service. Fire protection will be provided via 2 fire hydrants located within the development. 1 3.0 SEWER 3.1 Wastewater Generation *Waste water generation by the development is determined as follows: TOTAL WASTEWATER WASTEWATER TYPE UNIT #OF UNITS FLOW PER UNIT GENERATION (gpd/unit) (gpd) Multi Family Duplex 17 500 8500 Dwelling TOTAL 8500 gpd ** Wastewater flows are based on 100 gpcd and 2.5 people per household (250 gpdihousehold). The peak design flow as calculated from Figure 1 of "MDEQ, Circular WQB 1, 1995 Edition." 17 units x 5 persons/unit= 85 persons Capita in 1000's =0.085 Peaking Factor=4.26 Daily Flow 8,500 gpd/1440 min/day=5.9 GPM Peak Flow 5.9 x 4.26 =25.1 GPM (Use 25 GPM) 3.2 Sewer Capacity(Proposed System) Using the design peak flow of 25.0 GPM: 1.486 AR`13SI12 Q - Manning Equation n Try 8" Pipe at minimum slope of.4% flowing 2/3 full S =.004, A =.25 ft.Z,R=.19 ft., n =.013 Q= .60 efs =269 gpm 269 gpm > 25 gpm 2 An 8" pipe will be adequate for sewage produced within the development. 3.3 Sewer Capacity (Existing;System) The existing main on Lincoln Road is 10"diameter laid at a minimum grade of 0.28%. The capacity of the existing main on Lincoln Road is as follows: 0 _ 1.486 4 R 2/3 S liz Manning Equation n l 0" Pipe at minimum slope of.28% flowing 2/3 full S =.0028, A=.388 ft.Z, R=.24 ft., n =.013 Q= .91 cfs =407 gpm The existing main on Lincoln Road is capable of handling a sewage flow of 407 gpm flowing 2/3 full. A flow rate of 407 gpm has an approximate population equivalent of 1375 people. 407 gpm X 1440 min/day=586,080 gpd 586,080 gpd -4.26 peaking factor= 137,577 gpd 137,577 gpd- 100 gpcd= 1375.77 people There is adequate sewer capacity in the existing main on Lincoln Road to handle the increased flow from this development. In addition, flow data for the existing 8" sewer main on South 19th Avenue provided by the City of Bozeman shows that the peak flow near the intersection of Garfield Street and South 19th Avenue is currently 0.78 cfs. According to data provided by the City of Bozeman, this section of sewer main is capable of handling 1.43 cfs. The remaining capacity in this section of sewer main is 0.65 cfs or 292 gpm. The wastewater generation from the proposed development will be 25 gpm, therefore, there is adequate capacity in the existing sewer system in the immediate vicinity of the proposed development. 3 3.4 Depth The proposed sewer system has been designed with benefits to the city and specific site conditions as primary factors influencing the design. A minimum bury of 5' will be maintained in all areas. 3.5 Slope To achieve the minimum velocity of 2.0 feet per second (FPS) as per Section 24.31 of "Recommended Standards for Sewage Works", 1978 Edition, a minimum slope of.4 feet per 100 feet will be used with the 8" Dia pipe size. 4.0 DESIGN (water) 4.1 Domestic Demand: The requirements for the proposed water system are as follows: 17 units X 5.0 persons/unit X 100 GPD/person= 8,500 gpd TOTAL DOMESTIC DEMAND 8,500 GPD 4.2 Irriiyation Demand: Estimated irrigation requirements for the proposed expansion are as follows: ** 17 units X 267 gpd/unit =4,539 gpd TOTAL IRRIGATION DEMAND 4,539 GPD ** Cite "Wastewater Engineering"McGraw-Hill, 1972 3,000 SF lawn, 1 inch per week = 267 GPD irrigation TOTAL DOMESTIC& IRRIGATION DEMAND 13,039 GPD (or Average Daily Demand) 4 4.3 Fire Protection Demand: The minimum required fire protection capability is 1000 gpm for a minimum of 2 hours. 1000 gpm * 120 min = 120,000 gal 4.4 Maximum Day Demand: Use 2.8 peaking factor '. 13,039 GPD X 2.8 = 36,509 GPD MAXIMUM DAILY DEMAND (including fire protection) 156,509 GPD 4.5 Fire Flow Calculations Static Hydrant: ±160 LF East of intersection of Lincoln Road and 19th Avenue Hydrant Elevation: 4884.0 FT Observed Pressures: Static: 85 psi Residual: 78 psi Flow Hydrant: Intersection of Lincoln Road and 19th Avenue Hydrant Elevation: 4884.6 FT Observed Pressures: Pitot: 70 psi 1557.3 gpm Static, residual and pitot readings corrected to elevation of the new hydrant at the south end of the proposed water main extension: 4895.7 FT Static/Residual correction =:�-4895.7 FT -4884.0 FT= 11.7 FT 11.7 FT X 0.433 psi/FT=5.1 psi loss P�5=Corrected Static Pressure= 85 psi -5.1 psi =79.9 psi P,,=Corrected Residual Pressure= 78 psi - 5.1 psi= 72.9 psi 5 Pitot Correction =:>4895.7 FT - 4884.6 = 1 1.1 FT 1 1.1 FT X 0.433 psi/FT = 4.8 psi loss P�,=Corrected Pitot Pressure = 70 psi -4.8 psi =65.2 psi Note: Discharge coefficient of O.9.for smooth, rounded edge discharge openings considered above. Flow Available at 20 psi Qr= Qf X J-cs—PfI (Pcs- Pcr)o.sa Qr = Flow predicted at desired residual pressure Qf = Total flow measured during test Pc,, = Corrected static pressure Per = Corrected residual pressure Pd = Desired residual pressure Qr= 1557.3 gpm X (79.9 - 20)0.54 (79.9 - 72.9)0.54 Qr=4963.98 gpm Pressure at which 1000 gpm is available: PJ000 =P.S X P s= par�osali.ss Qf P = 79.9- [1000 79.9 - 72.9)0.5411.15 i000 — X 1557.3 P1000=76.82 psi 6 Line Losses from Flow Hydrant to New Hydrant: Line i s 160 LF 12" DIP H, cr 1000 gpm = 0.415 ft/100ft = 0.66 It Line 2: 1000LF 8" DIP H,, 1000 gpm = 3.02 ft/100ft= 30.2 ft Line 3: 450 LF 6" DIP H,, L' 1000 gpm = 11.5 ft/I00ft = 51.75 ft TOTAL = 82.61 FT 35.76 psi Assume Minor Losses = 10 FT or 4.3 psi Total Loss = 40 psi Flow Available at New Hvdrant: 1000 gpm at 36.8 psi Residual Pressure Static Pressure= 79.9 psi 4.6 Conclusion: There is adequate water available to provide domestic and fire flow to the proposed development. The above analysis is based on a dead end main assumption. The actual main extension will be looped which will provide significantly greater pressure and flow capability within the development. 5.0 PLANS & SPECIFICATIONS The plans&specifications for this project will accompany this report and will include the information required in the "Plans & Specifications" of Chapter 1 in MT Department of Health &Environmental Sciences' Circular WQB 1. ► Location, size, scope, depth, materials, and installation procedures of building and construction sewers, ► Elevation of sewer invert and ground surface, ► Location of manholes ► Location of proposed and existing water lines in the area of the proposed development and land adjacent to it, ► Lot boundaries. 7