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Home My WebLink About014_PreliminaryWaterEngineeringReportBlock4Engineering Report Water Main Extension South University District Phase 3 - Block 4 Site Plan Submittal Updated May 2023 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 5/19/2023 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 Figure 2. C2.0 - Water Plan Table 1. SUD Phase 3 Block 4 Estimated Water Design Flows Appendices Hydraulic Analysis Exhibit (To be provided with Infrastructure Submittal) Water Mains 2 5/19/2023 1.1.1 General Information The proposed South University District (SUD) Phase 3 Block 4 Development is located southwest of the intersection of South 11th Avenue and Student Drive. This development will consist of 243 residential units with 655 bedrooms on an 11.89-acre lot. Six different building types consisting of 20 unique unit configurations within the buildings is proposed with this development. The intent of this project is to create a variety of building types to create a diverse neighborhood in a growing part of town adjacent to the Montana State University Campus. The project will be served by extension of City of Bozeman water and sewer mains throughout the project. Individual service lines will be provided to each block of units. City of Bozeman water and sewer mains currently exist along the North side of the project site along Student Drive. The developer’s contact information is: Capstone Collegiate Communities Davis Maxwell 431 Office Park Drive Birmingham, AL 35223 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 Block 4 Development is shown on the Vicinity Map in Figure 1 Water Mains 3 5/19/2023 Figure 1. Vicinity Map, Bozeman, Montana 1.1.2 Extent of Water Works System Water supply to the area is from an existing 8” diameter water main in Student Dr. and a 12” main on S 11th Ave. New 8” water mains will be installed in the adjacent portions of S 14th Ave and Arnold Street as a part of the off-site subdivision improvements to service the proposed development. Additionally, new on-site water mains will be extended into the site in combined 30-foot-wide water and sewer easements. Each structure will have a single water service from the main to the riser room, with a curb stop located on the easement or right-of-way line. Preliminary service sizing indicates a range of 1 ½” to 4” services. The Block 4 water main extensions have 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 Mains 4 5/19/2023 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. Distribution alternatives were explored, and the proposed design was selected to increase looping and minimize dead ends. The use of an on-site well as a source for irrigation usage is not feasible due to the previously-allocated water rights in the Phase 2 subdivision park. 1.1.4. Site Conditions The SUD Phase 3 Block 4 site is typical of Bozeman with fine-grained soils overlying gravel deposits. Geotechnical borings have determined the depth to gravel ranges from 7.5 to 11 feet. Estimated depth to groundwater obtained from the geotechnical borings is 8 to 9. If mains are installed during periods of high groundwater, dewatering may be required. High groundwater and soil conditions in the area indicate potential for corrosion of ductile iron pipe. Composite soil samples were collected at typical depths of water main to test for corrosive soil conditions and found to be at low risk of corrosion. The full DIPRA Decision Model results and summary are included in a separate appendix of this submittal. 1.1.5. Water Use Data The estimated residential water use was based on the City of Bozeman design standards for wastewater generation. The estimated flow was determined based on 2.11 people per unit and an average daily flow rate of 89 gpd/person in accordance with the City of Bozeman Design Standards Utility Design Criteria. Site irrigation use was calculated by the Landscape Architect as shown in the landscaping plans. The following table displays the combined residential, commercial, and irrigation water design flows. Water Mains 5 5/19/2023 Table 1: SUD Phase 3 Block 4 Estimated Water Design Flows The design max day peak hour flow for the proposed Block 4 is 182.03 gpm. 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. 1.1.6. Flow Requirements As stated previously, the peak hour water demand is estimated to be 182.03 gallons per min (gpm). Fire flows have not been determined yet but will be in accordance with the City of Bozeman adopted Uniform Fire Code. It is anticipated that a fire flow of 1500 gpm will be required. The fire flow requirement will be the dominant design constraint for system design. As part of the Phase 3 Subdivision process, a hydraulic analysis was completed to determine the available fire flow in this area. According to this analysis, Phase 3 hydrants – including those in Block 4 – will have fire flows ranging from 3,122 gpm to 3,606 gpm, while maintaining a residual pressure within the system of 20 psi. Fire flow requirements are based on the Uniform Fire Code. The required hydrant flow is determined using Table H.5.1 of the Uniform Fire Code. For example, a 48,000 sq ft Type V-A building requires a fire flow of 4,000 gpm. In consideration of the planned use of sprinkler systems in future Phase 3 site developments projects, the fire department is allowing a 75% SUD Phase 3 Block 4 Estimated Water and Sewer Usage Site Area (acres)11.89 Bedrooms 655 Residential Occupants 655 Per Capita Use (gpd)89 Residential Flow (gpd)58,295 Commercial Area (sf)0 Commercial Use (gpd/1000 sf)0 Commercial Flow (gpd)0 Commercial and Residential Flows (gpd)58,295 Commercial and Residential Flows (gpm)40 Average Day Water Use [Equal to Commercial & Residntial Flows](gpd) 58,295 Irrigation (annual use in gal)1,047,045.00 Irrigation [based on annual use in a 120 day watering season] (gpd) 8,725 Irrigation per Capita (gpd)13 Max Day Water Use [Average Day Use + Irrigation] (gpd)67,020 Peaking Factor (PF)3.91 Design Water Peak Hour Flow 182.03 Water Mains 6 5/19/2023 reduction in required fire flows, reducing the hydrant flow down to the anticipated minimum required fire flow of 1500 gpm. The fire flow required will be determined by the fire department at the time of infrastructure design. The total fire flow available will allow for the use of the hydrant and the sprinkler while maintaining the required 20 psi residual pressure. The Phase 3 Subdivision Engineer’s Water report is available upon request. 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 mains extended through the site from the existing sewer main running along the northern portion of the property. Sewers will be approximately 8.5 feet deep and primarily cross below water mains and services. 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 The water system layout accommodates future water main extensions as required to complete future system improvements in this area. 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