HomeMy WebLinkAboutZMA Tech Memo-Combined
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Technical Memorandum
Date: 3/7/2024
Project: 24024 1920 W Babcock ZMA
RE: Response to Plan Review – Review Comments Report (Engineering) 3/4/2024
Narrative:
The following memo is to address comments provided by Suzanne Ryan (City of Bozeman Engineering)
on 2/6/2024.
The subject ZMA is to change the existing zoning from Residential Office (R-O) to Community Business
District-Mixed (B-2M). The legal description of the ZMA is:
A portion of land being Lot 10, Block 1 of the Kirk Subdivision (Plat F-1), and the adjoining 30
feet of Right-of-Way for West Babcock Street and South 20th Ave., located in Sec. 11, T. 2 S., R.
5 E., City of Bozeman, Gallatin County, Montana, containing 18,322 square feet or 0.421 acres.
Lot 10, Block 1 of the Kirk Subdivision (Plat F-1) which is the parcel that will actually be re-
developed contains 10,843 square feet or 0.248 acres.
The subject ZMA area was previously used as an Allstate Insurance Agency. The business was in a
structure that was originally a single-family home that was converted to commercial use. The previous
structure has since been demolished and Lot 10 is vacant. The number of employees and customers that
occupied the demolished insurance agency building is unknown and the insurance agent has since passed
away.
The proposed building to be constructed on Lot 10 is a 5-plex residential structure that will have (3) 2-
bedroom units and (2) 3-bedroom units. The estimated population of the building is (5 units x 2.11
people/unit) 10.55 people.
Being the previous building has been demolished and the employee and customer occupancy is unknown
these calculations use the original single-family occupancy of the building in comparing existing and
proposed zoning water, wastewater and traffic demands.
Water Demand:
Proposed Zoning (B2-M)
Fire-Flow -- The building construction type for the proposed 5-plex residential structure is Type
V-B, building area is 6,580 sq-ft. The structure will be equipped with an automatic fire sprinkler
system. Based on Table B105.1, Appendix B, IFC, the required fire-flow is 2,250 gpm for 2
hours. Being the building is equipped with an automated fire sprinkler system, the fire-flow is
reduced to 1,500 gpm for 2 hours.
Domestic / Irrigation Use -- (Based Section V. of the COB Design Standards)
Average Daily Usage = 10.55 People x 170 gpd/person = 1,793.50 gpd
Maximum Day = Average Day x 2.3 = 4,125.00 gpd
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Max Hour = (Average Day x 3.0)/24 = 224.2 gph
Peak Instantaneous = 19 GPM (see attached AWWA M22)
Existing Zoning (R-O)
Fire-Flow – Being the previous building on the site has been demolished and was originally a
single-family home we assume s fire-flow of 1,500 gpm for 2 hours.
Domestic / Irrigation Use (Based Section V. of the COB Design Standards) assumes the previous
now demolished structure had a water use equivalent to one single family home which was the
original use of the structure.
Average Daily Usage = 2.11 People x 170 gpd/person = 358.70 gpd
Maximum Day = Average Day x 2.3 = 825.00
Max Hour = (Average Day x 3.0)/24 = 44.84 gph
Peak Instantaneous = 24 GPM (see attached AWWA M22)
Comparison Existing (R-O) to Proposed Zoning (B2-M)
Peak Instantaneous + Fire Flow
Existing (R-O) = 1519
Proposed (B2-M) = 1524
Peak Hour Water Demand
Existing (R-O) = 45 gpd
Proposed (B2-M) = 224 gpd
Wastewater Demand:
Proposed Zoning (B2-M) – Based on 5 dwelling units
Wastewater Flow -- (Based Section B. of the COB Design Standards)
Average Daily Usage = 10.55 People x 89 gpd/person = 939 gpd
Infiltration = 0.421 ac. x 150 gallons/ac./day = 63 gpd
Total Average Daily Usage = 1,002 gpd
Maximum Day = Average Day x 2.3 = 2,305 gpd
Max Hour = (Average Day x 3.0)/24 = 3,006 gph
Existing Zoning (R-O) – Based on 1 dwelling units
Wastewater Flow -- (Based Section B. of the COB Design Standards)
Average Daily Usage = 2.11 People x 89 gpd/person = 188 gpd
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Infiltration = 0.421 ac. x 150 gallons/ac./day = 63 gpd
Total Average Daily Usage = 251 gpd
Maximum Day = Average Day x 2.3 = 577 gpd
Max Hour = (Average Day x 3.0)/24 = 753 gph
Traffic:
Proposed Zoning (B2-M) – Based on ITE Code 220 and 5 dwelling units
Average Daily Trips = 34 Trips
Peak AM (7-9) = 2 Trips
Peak PM (4-6) = 3 Trips
Existing Zoning (R-O) – Based on 1 dwelling units
Average Daily Trips = 9.4 Trips
Peak AM (7-9) = 1 Trips
Peak PM (4-6) = 1 Trips
Prepared by Clint Litle, PE
Facility Name
Building address or number
Residential or Non-Residential
Minimum Pressure (psi)
Fixture Value Number of Subtotal
Fixture or Appliance (at 60 psi)Fixtures Fixture Value
Toilet (Flushometer Tank) 1.3 2 2.6
Toilet (flush valve)0 0
Urinal (Flushometer Valve) 2 0 0
Urinal (flush valve)0 0
Bidet 0 0
Shower (single head)2 2 4
Sink (lavatory)1 2 2
Kitchen Sink 1.5 1 1.5
Utility Sink 1.5 1 1.5
Dishwasher 1.5 1 1.5
Bathtub 0 0
Clothes Washer 6 1 6
Hose connections (with 50 ft of hose)
1/2 in. 2.5 2 5
5/8 in. 9 0 0
3/4 in. 12 0 0
Miscellaneous
Bedpan washers 10 0
Drinking fountains 2 0 0
Dental units 2 0
Combined Fixture Value 24.1
Demand (gpm)19
Pressure Adjustment Factor 1
Total Adjusted demand (gpm)19
Water Demand Estimate Using Fixture Values
(Based on AWWA M22 Manual, Second Edition)
Ex. RO Zoning - 1920 W. Babcock ZMA
Note: Fixture count based on City of Bozeman Water Service Calculation Worksheet - Commercial
(2018 IBC), UPC Table 610.3 Standard Design Water Supply Fixture Units
Facility Name
Building address or number
Residential or Non-Residential
Minimum Pressure (psi)
Fixture Value Number of Subtotal
Fixture or Appliance (at 60 psi)Fixtures Fixture Value
Toilet (Flushometer Tank) 1.3 10 13
Toilet (flush valve)0 0
Urinal (Flushometer Valve) 2 0 0
Urinal (flush valve)0 0
Bidet 0 0
Shower (single head)2 10 20
Sink (lavatory)1 10 10
Kitchen Sink 1.5 5 7.5
Utility Sink 1.5 5 7.5
Dishwasher 1.5 5 7.5
Bathtub 0 0
Clothes Washer 6 5 30
Hose connections (with 50 ft of hose)
1/2 in. 2.5 4 10
5/8 in. 9 0 0
3/4 in. 12 0 0
Miscellaneous
Bedpan washers 10 0
Drinking fountains 2 0 0
Dental units 2 0
Combined Fixture Value 105.5
Demand (gpm)24
Pressure Adjustment Factor 1
Total Adjusted demand (gpm)24
Water Demand Estimate Using Fixture Values
(Based on AWWA M22 Manual, Second Edition)
Proposed B-2M Zoning - 1920 W. Babcock ZMA
Note: Fixture count based on City of Bozeman Water Service Calculation Worksheet - Commercial
(2018 IBC), UPC Table 610.3 Standard Design Water Supply Fixture Units