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HomeMy WebLinkAbout21 - Design Report - Housing First Village - WaterEngineering Report Water Main Extension Housing First Village Updated - January 2021 Submitted to: City of Bozeman Engineering Department 20 East Olive Bozeman, MT 59715 Prepared by: Stahly Engineering and Associates 851 Bridger Drive, Suite 1 Bozeman, MT 59715 (406) 522-8594 Water Mains 1 1/13/2021 Engineering Report Contents Note: The Engineering Report format follows DEQ-1 organization. Additional information required by the City of Bozeman Design Standards is added where required. Report Narrative 1.1.1 General Information 1.1.2 Extent of water works system 1.1.3 Alternate plans 1.1.4 Site conditions 1.1.5 Water use data 1.1.6 Flow requirements 1.1.7 Sources of water supply 1.1.8 Proposed treatment processes 1.1.9 Sewage system available 1.1.10 Waste disposal 1.1.11 Automation 1.1.12 Project Sites 1.1.13 Financing 1.1.14 Future Extensions Figures and Tables Figure 1. Vicinity Map Appendices C2.0 – Water Plan Hydraulic Analysis Hydrant Flow test Water Mains 2 1/13/2021 1.1.1 General Information The Housing First Village is a proposed development located on the western end of Wheat Drive, north of Interstate 90 (I-90) and south of Mandeville Lane. The Housing First Village is a group of multiple “tiny homes” approximately 200 square feet each, with some basic communal infrastructure in a compact, urban style. The project is located at 2007 Wheat Drive on Lot 2 of the Wheat Commercial Subdivision Amended and is development ready. Future phases may occur on Tract A, approximately 5.4 acres, located immediately west of Lot 2 (see Figure 1). City of Bozeman water main runs within Wheat Drive right-of-way to the east of the site, as well as just west of the property boundary in a north- south alignment. The project includes the construction of 19 individual tiny homes. This includes 16 typical units and 3 ADA units. The development will also feature a drive aisle, 5 parking spaces, a drivable surface running the length of the development, and a communal courtyard space. The individual units will remain on the common lot. Drinking water supply for the project will be supplied by a connection to the 12” main that runs just beyond the western property boundary and extending an 8” water main into the site. From the 8” main, a 2” water main will be extended into a meter riser room. From the meter riser room, the 2” water main will be extended throughout the site. Individual connections will be made to each of the “tiny homes” from this main extension. The developer’s contact information is: HRDC Tracy Menuez 32 South Tracy Ave. Bozeman, MT 59715 Water supply and wastewater treatment will be provided by the City of Bozeman’s municipal systems. The system owner’s contact information is: City of Bozeman Public Service Department PO Box 1230 Bozeman, MT 59771-1230 The location of the Housing First Village is shown on the Vicinity Map in Figure 1. Water Mains 3 1/13/2021 Figure 1. Vicinity Map, Bozeman, Montana 1.1.2 Extent of Water Works System Water supply in the area consists of an existing 8” water main running along Wheat Drive east of the site, and a 12” main that runs along the western boundary of the site. Housing First Village’s water supply will come from tying into the lower pressure 12” water main to the west. As illustrated on attached Figure “Sheet C2.0”, a new 8” main will extend east from the existing 12” main along the drive aisle for approximately 100 feet terminating at a fire hydrant. A 2” tap will be made into the proposed new 8” water main that will run south into the riser room for metering. This 2” Type K copper water main is required for proper water meter sizing. After the angle stop, meter, backflow preventor, and pressure reducing valve, the 2” copper line will reenter the ground and extend throughout the site. The 19 individual connections will be made to this approximately 260’ run, which aligns with the western edge of the drivable surface. A blowoff hydrant will be installed at the end of the 2” water main. The Housing First Village water main extension has been designed in accordance with Montana Department of Environmental Quality Circular 1, and the City of Bozeman Design Standards and Specifications Policy. Construction specifications will be Montana Public Works Standards and Specifications (MPWSS), and the City of Bozeman Modifications to MPWSS. Water and sewer utility easements are proposed for the sites water and sewer mains. The easements are variable width but at no point are they Water Mains 4 1/13/2021 less than 30 feet in width. Easement extents are shown on the attached Sheet C2.0. Each unit on the property will have an individual 3/4” service connection at the front of the structure, with a curb-stop located on or near the easement line. Due to the large number of individual water and sewer connections required, a 5’ separation between water and sewer services is necessary. This non-standard service separation will allow water and sewer connections to the tiny homes (some models only being 10-ft wide) and allow for trees to be planted in the front yards and common open spaces. Without this non-standard service separation, very few trees could be planted on the site. To avoid conflict with water and sewer services, franchise utilities will run behind the homes in a 15’ utility easement along the western and southern borders of the site and through open space along the eastern edge of the site. Future phases of development to the west, in Tract A, would require main extensions. Adjacent lots in the Wheat Commercial Subdivision have already been developed. 1.1.3 Alternate Plans Due to the project’s location within the City of Bozeman, extension of public mains was the only water supply alternative. Several different distribution arrangements were considered, including connecting to the 8” main running along Wheat Drive. Looping the mains was considered but the site is located at the boundary of the City of Bozeman’s Northeast and Northwest water distribution pressure zones and would require a pressure reducing valve. The primary challenge for this development is the large number of individual connections in such a relatively small area, with the individual homes remaining on a single common lot. Ultimately, this design was chosen for its effectiveness at facilitating and arranging these individual connections. 1.1.4. Site Conditions The Housing First Village site is located on a currently undeveloped lot of the existing Wheat Commercial Subdivision Amended. The site is considered “development ready” as it has already undergone the subdivision review and approval process. All other lots in this subdivision have been developed. 8” water and sewer mains currently run along Wheat Drive, directly east of the site. A 12” water main runs in a north- south alignment just west of the property boundary. Water Mains 5 1/13/2021 The soil on the site is characterized by an approximately 1’ thick layer of dark silty clay topsoil underlain by an approximately 2’ fine-grained deposit of light brown silt and lean clay with abundant roots. Below this, flood and windblown deposits of silt and lean clay extend to a depth of approximately 9’. This soil can be susceptible to excessive settlement and even collapse under saturated conditions. A layer of dense alluvial sandy gravel underlies the flood and windblown deposits. A geotechnical evaluation of the site was conducted and is provided as a separate appendix with this submittal. Groundwater was observed in the test pits during geotechnical investigation of the site at a depth of approximately 9’. For this reason, two monitoring wells were installed to a depth of approximately 10’ and groundwater monitoring was conducted during the high groundwater season of 2020. Both groundwater monitoring wells were dry in all subsequent visits. Groundwater is not anticipated to impact utilities, and the structures proposed on site do not have basements. Groundwater monitoring results are included with the Geotechnical report and are provided separately in the appendices. 1.1.5. Water Use Data Domestic water will be provided by the City of Bozeman Municipal system. This project is located within the planned service area of the City’s system. Estimated water use for the Housing First Village has been determined utilizing values provided in City Design Standards and Facility Plans. There are characteristics of this development that make estimating water use somewhat atypical. The units on this site are very small. Typically, an average population per residence of 2.11 is used in the City of Bozeman for water use estimates. A typical home in Bozeman is approximately 1800 square feet. However, the average unit at Housing First Village has an interior floor space of approximately 200 square feet. Additionally, as the development serves a transient population on a night-by-night basis, occupancy is subject to fluctuation. For water use estimates, 1.25 residents per unit with a year-round 100% occupancy rate has been assumed. A peaking factor of 8:1 was used to determine the peak hour flow rate. The estimated total project design flow is 998 gpd with a peak flow of 47.5 gpm. For estimating annual water use, an average of 42.0 gpd/capita was used based on values provided by the City of Bozeman. Due to the very small homes on the site, as well as the possibility of inconsistent occupancy, actual water use may be significantly lower. Annual domestic water use is estimated to be 1.12 acre-feet of water. Payment of cash-in-lieu of water Water Mains 6 1/13/2021 rights will be used to provide water rights for this project, for a cost of $10,800. Irrigation will be supplied by connection to City of Bozeman water service. Irrigation lines will provide water to the trees and open spaces on the site. The irrigation system will be maintained by HRDC. Drought tolerant plants and a drip irrigation system are proposed to conserve water. Approximately 0.57 acres will be irrigated by spray irrigation. Drip irrigation and tree bubblers will be used for planters and trees. The irrigation system will be “high-efficiency” and will use an estimated 0.55 acre-feet per year. 1.1.6. Flow Requirements As stated previously, the peak hour water demand is estimated to be 9.4 gallons per min (gpm). A flow of 1500 gpm is required for adequate fire suppression water supply. The fire flow requirement will be the dominant design constraint for system design. Fire flow testing was performed on a hydrant near the site during the City of Bozeman’s 2017 Water Facility Plan Update. The test was performed on the City Hydrant “653” located on Wheat Drive—approximately 150 ft east of the project site. The test reported a static water pressure of 117.14 psi, and a flow rate of 1,600 gpm with a residual water pressure of 106.31 psi. This indicates that the water system network in this area can provide fire flows as well as peak domestic demand with little impact on the system pressures. We received pressure information in the site from the Engineering Department which stated the pressure in the 12” main that this development is tapping into has a residual pressure of 117 psi at a node at the southwest corner of the site. Hydraulic calculations show flows of 1500 gpm from the new fire hydrant, with just a 4 psi drop in pressure The internal water main extension will be a 2” Type K copper main after a master water meter, pressure reducing valve and backflow preventer assembly in an on-site riser room. The pressure will be stepped down to 80 psi before supplying the 19 individual units. The peak flow is only estimated to be 47.5 gpm for the development, which results in line velocities of 4.85 ft/sec. The 2” tap was selected for the most appropriate meter for the anticipated flows. Flushing velocities of 2.5 ft/sec can be achieved while keeping velocities in the 2” main under 10 ft/sec. See enclosed hydraulic calculations. Water Mains 7 1/13/2021 1.1.7. Sources of Water Supply This section is not applicable. 1.1.8. Proposed Treatment Process This section is not applicable. 1.1.9 Sewage System Available Sewer service is provided by new City of Bozeman mains extended through the site from the 8” main running within the Wheat Drive right-of- way. The sewer main will be extended west along the drive aisle then south along the alignment of the drivable surface in a shared 30’ water and sewer easement. Individual connections sewer connections will be made from the homes to this main extension. There will be a single crossing of water and sewer main on this project, on the northern end of the drive-able surface. Appropriate minimum separation at this crossing is included in design. 1.1.10 Waste Disposal This section is not applicable. 1.1.11 Automation This section is not applicable. 1.1.12 Project Sites This section is not applicable. 1.1.13 Financing This section is not applicable. 1.1.14 Future Extensions Future phases of development may occur immediately west of the lot, in Tract 2A. Extensions of City of Bozeman water mains will be required to serve any development. LOT 2I-90DRIVE AISLE(5)PARKING20' DRIVABLE SURFACELYNXPIKACOTTONTAILLYNXPIKABOBCATSTORAGE12' DRIVABLE SURFACECOTTONTAILCOTTONTAILPIKAPIKABOBCATBOBCATLYNXLYNXMARMOTMARMOTMARMOT MARMOT UTILITYROOM(BLDG - 1)COTTONTAIL(BLDG - 2)(BLDG - 3)(BLDG - 4)(BLDG - 5)(BLDG - 6)(BLDG - 7)(BLDG - 8)(BLDG - 9)(BLDG - 10)(BLDG - 11)(BLDG - 12)(BLDG - 19) (BLDG - 18)(BLDG - 17)(BLDG - 16)(BLDG - 15)(BLDG - 14)(BLDG - 13)C 2.0WATER PLANPROFESSIONALENGINEERS &SURVEYORSHOUSING FIRST VILLAGE STAHLYENGINEERING& ASSOCIATESHRDC BOZEMAN MONTANA Worksheet for Pressure Pipe - 8" main Project Description Manning FormulaFriction Method Pressure at 2Solve For Input Data psi117Pressure 1 ft4,725.00Elevation 1 ft4,726.50Elevation 2 ft120.0Length 0.012Roughness Coefficient in8.0Diameter gpm1,500.00Discharge Results psi113Pressure 2 ft7.82Headloss ft4,996.29Energy Grade 1 ft4,988.47Energy Grade 2 ft4,994.87Hydraulic Grade 1 ft4,987.05Hydraulic Grade 2 ft²0.3Flow Area ft2.1Wetted Perimeter ft/s9.57Velocity ft1.42Velocity Head ft/ft0.065Friction Slope Page 1 of 127 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 12/16/2020 FlowMaster [10.03.00.03] Bentley Systems, Inc. Haestad Methods Solution CenterHousing First Village-FH flow.fm8 This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. Worksheet for Pressure Pipe - 2" main Project Description Hazen-Williams FormulaFriction Method Pressure at 2Solve For Input Data psi80Pressure 1 ft4,500.00Elevation 1 ft4,505.00Elevation 2 ft320.0Length 130.00Roughness Coefficient 2.0 inDiameter 47.50 gpmDischarge Results 70 psiPressure 2 17.73 ftHeadloss 4,684.89 ftEnergy Grade 1 4,687.16ftEnergy Grade 2 ft4,684.53Hydraulic Grade 1 4,666.80 ftHydraulic Grade 2 0.0 ft²Flow Area 0.5 ftWetted Perimeter 4.85 ft/sVelocity 0.37 ftVelocity Head 0.055 ft/ftFriction Slope Page 1 of 127 Siemon Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 FlowMaster [10.03.00.03] Bentley Systems, Inc. Haestad Methods Solution CenterHousing First Village.fm8 1/12/2021 This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. GIS Hydrant #Available Flow (gpm) Residual Pressure (psi)6530 117.14200 114.47400 111.53600 110.36800 109.861,000.00 109.171,200.00 108.351,400.00 107.391,600.00 106.311,800.00 105.112,000.00 103.792,200.00 102.372,400.00 100.842,600.00 99.212,800.00 97.483,000.00 95.653,200.00 93.733,400.00 91.723,600.00 89.633,800.00 87.474,000.00 85.224,200.00 82.894,400.00 80.494,600.00 78.014,800.00 75.475,000.00 72.865,200.00 70.25,400.00 67.55,600.00 64.775,800.00 62.046,000.00 58.716,200.00 55.276,400.00 51.746,600.00 48.116,800.00 43.77,000.00 38.677,200.00 33.57,400.00 28.217,600.00 22.797,800.00 17.258,000.00 11.588,200.00 5.798,390.80 0.15Hydrant Curve 0204060801001201400 1000 2000 3000 4000 5000 6000 7000 8000 9000Residual Pressure (psi)Available Flow (gpm)Hydrant Curve 653Data 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.