HomeMy WebLinkAbout016 Appendix O - Water Engineers ReportEngineering Report
Water Main Extension
Aaker Phase 1 Subdivision
Preliminary Report for Preliminary Plat Review
October 2022
Rev. March 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 3/23/2023
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
Table 1. Aaker Phase 1 Subdivision Estimated Water Use
Attachments and Appendices
C 2.0. Water Plan
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1.1.1 Engineering Report – General Information
The Aaker property consists of approximately 95 acres of vacant land located west of
South 19th Avenue, north of Stucky Road, and extending west and north to the MSU
BART Farm. Concept master planning and initial REMU and B-2M zoning of the Aaker
property envision a mixed-use development with commercial uses along South 19th
Avenue grading to predominantly residential uses toward the north and west. The
Phase 1 Subdivision includes the extension of Kagy Boulevard and the land to the
north, comprising 31.73 acres, with a 63.68-acre restricted future development lot south
of Kagy Boulevard. Phase 1 will create 7 lots for development with REMU zoning.
Planned land use includes moderate density residential with some commercial uses
integrated into lots adjacent to Kagy Boulevard.
Water and sewer service for the subdivision will be provided by extensions from existing
City of Bozeman water and sewer mains adjacent to the site.
The developer’s contact information is:
West University, LLC
113 East Oak, Suite 4A
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
Figure 1 shows a vicinity map of the Aaker Property and Phase 1 Subdivision.
Figure 1. Vicinity Map, Bozeman, Montana
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1.1.1 Extent of Water Works System
This area of town is supplied primarily by an existing 24” water main in South 19th
Avenue. Smaller 8” water mains in Kagy Boulevard and Remington Way
currently run from South 19th Avenue to the Aaker property.
New 8” water mains will be extended in proposed subdivision streets within the
Aaker Phase 1 Subdivision. This subdivision will provide approximately 4500
linear feet of 8” water main connecting to existing mains in two locations. In
addition, nine (9) new fire hydrants are proposed with the development.
Proposed water mains will be extended to the exterior subdivision boundary and
planned street alignments, to allow for future extensions and connections to
planned future large diameter trunk lines in Stucky Road, Lincoln Street, and
South 27th Avenue. The proposed water system improvements are shown on the
C2.0 Ph. 1 Water Plan, attached at the end of this report.
Due to the large lot size, it is anticipated that future lot development will require
on-site main extensions to serve future development. Water main stubs are
provided to the lot lines where on-site main extensions are envisioned.
Proposed Phase 1 and future phase public parks will be irrigated by wells. The
planned total park irrigation is estimated to be approximately 8.68 acre-feet per
year, within the 10 acre-feet exemption. Private lots and street boulevard
landscaping will be irrigated with City water. Kagy Boulevard and the east side of
South 23rd Avenue will be landscaped with the subdivision improvements and are
proposed to be irrigated by two dedicated water service/meter pits for the street
landscaping.
The Aaker Phase 1 Subdivision water main extensions will be 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.
1.1.2 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 facilitate future extensions
and connectivity.
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1.1.4. Site Conditions
The Aaker Phase 1 property was previously used for agriculture. The site slopes
generally to the north and contains a stream and wetland in the western portion
of the site.
A geotechnical investigation was conducted, and the report is provided
separately with the subdivision submittal. In summary, the geotechnical
investigation found a variable depth of fine-grained soils overlying gravel
sediments. The depth to gravel varies between 1 and 4 feet.
Groundwater monitoring was conducted throughout the 2022 season. Depth to
seasonal high groundwater varied from near the surface in the wetlands to about
3-4’ below ground at the proposed lots. Groundwater is generally flowing to the
north.
Proposed street and lot grading will raise the developed portions of the site
approximately 2-3’ resulting in a typical depth to seasonal high groundwater in
developed areas of about 5-7’.
Groundwater dewatering may be required during water main installation,
depending on groundwater depth at the time of installation.
1.1.5. Water Use Data
Domestic and lot irrigation 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.
At the time of subdivision, the ultimate domestic and irrigation water use of the
lots are unknown. For the purposes of preliminary design and water main sizing,
the water use for the Aaker Phase 1 Subdivision has been estimated in Table 1.
Estimated domestic water use for each lot is based on planned use and density,
utilizing standard City of Bozeman design values. Because the proposed
development is multifamily or mixed use, the domestic water use and irrigation
use are calculated separately. The domestic water use is assumed to be the
same as the wastewater generation at 89 gpd per capita. Irrigation is estimated
based on 25% of the lot and street area being irrigated, at typical irrigation rates
of about 1” per week.
Public Park irrigation will be provided by exempt well(s) and is within the 10 acre-
feet limit of this exemption. Kagy Boulevard street landscaping to be completed
with the subdivision improvements will be irrigated with City water. Cash-in-lieu
of water rights for Kagy Boulevard and east side of South 23rd street landscaping
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have been estimated on the landscape plans included with this submittal to be
5.8 acre-feet. Payment for these water rights will be made at Final Plat.
Payment of cash-in-lieu of water rights for the individual lots will be made at the
time of lot development as determined during each lot’s site plan review.
Table 1. Aaker Phase 1 Subdivision Estimated Water Use
1.1.6. Flow Requirements
As stated above, the peak hour water demand is estimated to be 313 gpm. The
subdivision water mains will also provide fire protection water supplies (fire flow).
Final fire flow requirements for each building are unknown at this time, but the
2017 City of Bozeman Water Facility Plan did not identify any fire flow capacity
limitations in this area. This peak hour water use and anticipated fire flow is
within the typical capacity of a network of looped 8” water mains.
Further analysis and modelling will be conducted in final infrastructure design to
confirm the availability of fire flows with the proposed design.
Aaker Ph. 1 Subdvision Estimated Water Use
Residential Commercial
Units Capita/Unit Population GPD/Capita Residential
Sewer Use (gpd)
Commercial
Space (sf)
GPD/1000 SF
Commercial Space
Commercial
Sewer Use (gpd)
Block 1
Lot 1 0 2.11 0 89 - 20,000 100 2,000
Block 2
Lot 1 125 2.11 264 89 23,474
Lot 2 125 2.11 264 89 23,474
Block 3
Lot 1 52 2.11 110 89 9,765
Lot 2 52 2.11 110 89 9,765
Lot 3 68 2.11 143 89 12,770 10,000 100 1,000
Lot 4 68 2.11 143 89 12,770 10,000 100 1,000
Total Units 490 40000
Total Population 1034 Residential
Subtotal 92,017 Commercial Subtotal 4,000
Site Area - Lots and
ROW (ac)22.89
Average Day Water Use [Equal to Domestic Sewer Use](gpd) 96,017
Irrigated Area = Site Area (ac) * 0.25 5.72
Irrigation (gal/ac/day)4,000
Irrigation (gpd)22,890
Max Day Water Use [Average Day Use + Irrigation] (gpd)118,907
;P = Pop. ÷ 1,000 Peaking Factor (PF)3.79
Design Water Peak Hour Flow 313
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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 sewer mains extended through the site
from existing sewer mains in Kagy Boulevard and Lincoln Street Sewers will be
approximately 9-10 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
Proposed water mains will be extended to the exterior subdivision boundary and
planned street alignments, to allow for future extensions and connections to
planned future large diameter trunk lines in Stucky Road, Lincoln Street, and
South 27th Avenue.
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1 5-13-22 PHASE 1 PRE-APP CDP ZWL
2 10/11/2022 PRELIMINARY PRICING CDP ZWL
3 10/26/2022 PRELIMINARY PLAT CDP ZWL
4 2/2/2023 PRELIM PLAT RC1 CDP ZWL
5 3/23/2023 PRELIM PLAT RC2 CDP ZWL PROFESSIONALENGINEERS &SURVEYORSSTAHLYENGINEERING& ASSOCIATESAAKER PHASE 1 SUBDIVISION
LOCATED IN THE SE 14 OFSECTION 14, T2S, R5EWEST UNIVERSITY, LLCBOZEMAN, MONTANAC2.0PHASE 1WATER PLAN