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204 N. 11th Ave. BOZEMAN, MT 59715 406‐581‐3319 www.g‐e‐i.net
204 N. 11th Ave., Bozeman, MT 59715 Cell: (406) 581-3319 www.g-e-i.net Page 1 of 4
TECHNICAL MEMO December 20, 2024
Project: 24428 ‐ 1519 Alder Court ANNX
Re: Response to Plan Review – Review Comments (Engineering) – Comment #6
The following memo is to address the remaining comment #6 provided by Susanne Ryan.
COMMENT #6:
“The applicant is proposing a and zone map amendment to the existing
subject site. The change in the zoning from R‐S to R‐4 requires the applicant
to provide additional information on how the proposed change will affect the
transportation, water, and sanitary sewer demands. The applicant must
provide the following information to the engineering department as part of
the zone map amendment application. 1) Water Demands The applicant
must provide the maximum water demand plus fire flow and peak hour
water demand associated with the proposed zoning. A comparison between
the existing and proposed water use must be provided. 2) The applicant must
provide the peak hour sanitary flow rate associated with the proposed
zoning. A comparison between the existing and proposed sanitary sewer
demand use must be provided. a. The applicant must include an infiltration
rate of 150 gal/acre/per day to all flow calculations. 3) The applicant must
provide the average daily trips as well as the peak AM and PM trips
associated with the proposed zoning. A comparison between the existing and
proposed traffic demand must be provided. The analysis must be submitted
in a technical memo format. The analysis should provide a simple narrative
and supporting exhibits, if necessary, to help document proposed changes in
demands on the system. Lastly, the analysis must be prepared and stamped
by a professional engineer licensed in the State of Montana. The applicant is
advised that additional information or supporting documentation may be
necessary depending on the analysis.”
204 N. 11th Ave., Bozeman, MT 59715 Cell: (406) 581-3319 www.g-e-i.net Page 2 of 4
RESPONSE:
The subject ZMA is requesting a change from the existing zoning of R‐S to R‐4. The Legal
Description of the ZMA is Lot 25 of the Beatty's Alder Court Subdivision, Plat E‐46, S13, T2S, R5E,
P.M.M., Gallatin County, MT.
The current single‐family home is in the county with annexation being requested. The owners
intend to annex their 0.3‐acre lot into the City of Bozeman and simultaneously amend the zoning
map as required by the annexation application process. The owners are proposing to demolish the
existing single‐family house and construct a multi‐family condominium similar to the adjacent
structure to the north.
Below is the comparison of the impacts from a single‐family home with respect to the proposed
multi‐family condominium on this lot.
COMPARISON:
The existing structure is a 3 bedroom single‐family home and the proposed structure is an 6 unit
multifamily condominium.
Current structure population is 2.11 people per unit or a total 2.11 persons.
The proposed structure population is 2.11 people per unit or a total of (6 X 2.11) 12.7 persons.
1. Potable Water Demand
Existing 3‐Bedroom Single‐Family Home
Average Daily Water Use: Based on the City of Bozeman’s design guidelines, a typical single‐
family home has 2.11 people and an average daily potable water demand of 110 gallons per
day per person for a total of 232 gallons per day or 84,738 gallons per year.
Max Daily Demand: Accounting for a peaking factor of 2.3, the Max daily demand is 533.6
gpd or 0.4 gpm.
Peak Hour Demand: Accounting for a peaking factor of 3.0, the Peak Hour Demand is 696
gpd or 0.5 gpm.
Irrigation Demand: 7,300 sqft lawn at 1.5‐inches of water per week yields 6,823 gallons of
water per week and over a 20 week growing season, that is a total of 136,460 gallons of
water per year.
Proposed 6‐Unit Condominium
Average Daily Water Use: Assuming an average daily demand of 232 gpd per unit, the total
demand is 1,392 gpd or 508,428 gallons per year for the complex.
Max Daily Demand: With a peaking factor of 2.3, the max daily demand is 3,202 gpd or 2.2
gpm.
Peak Hour Demand: Accounting for a peaking factor of 3.0, the Peak Hour Demand is 4,176
gpd or 2.9 gpm.
Irrigation Demand: Since no lawn is proposed the irrigation demand will be almost nothing.
204 N. 11th Ave., Bozeman, MT 59715 Cell: (406) 581-3319 www.g-e-i.net Page 3 of 4
2. Fire Flows
Existing 3‐Bedroom Single‐Family Home
Flow Requirements: Single‐family homes typically require a fire flow of 1,500 gallons per
minute (gpm) for a duration of 2 hour, as per local fire code standards.
Proposed 6‐Unit Condominium
Flow Requirements: Multifamily developments generally require higher fire flows or will
require a fire suppression system. We anticipate a similar fire flow in the range of 1,500
gpm for a duration of 2 hours.
3. Wastewater Generation
Existing 3‐Bedroom Single‐Family Home
Average Daily Wastewater Flow: Typically, 90% of potable water demand is assumed to
return as wastewater. For a single‐family home, this equates to 211 gpd and 77,067 gallons
in a year.
Infiltration of 150 gpd/acre: 150 gpd/acre X 0.30 acres = 45 gpd
Peak Hour Flow: Accounting for a PHF of 4.5, the sewage peak hour flow is 950 gpd + 45
gpd for a total of 995 gpd.
Proposed 6‐Unit Condominium
Average Daily Wastewater Flow: Similarly, 90% of the potable water demand for the
condominium complex results in a wastewater generation of 1,253 gpd and 457,585 gallons
in a year.
Infiltration of 150 gpd/acre: 150 gpd/acre X 0.30 acres = 45 gpd
Peak Hour Flow: Accounting for a PHF of 4.4, the sewage peak hour flow is 5,513 gpd + 45
gpd for a total of 5,558 gpd.
4. Traffic Impact
Existing 3‐Bedroom Single‐Family Home
Trip Generation: Using the Institute of Transportation Engineers (ITE) Trip Generation
Manual, a single‐family home generates approximately 10 daily vehicle trips.
Peak Hour Trips: During peak hours, 1‐2 trips are typical.
Proposed 6‐Unit Condominium
Trip Generation: Multifamily residential developments generate approximately 6 daily trips
per unit. For a 6‐unit complex, this results in 36 daily vehicle trips.
Peak Hour Trips: Peak hour trip generation is estimated at 4‐5 trips during the morning and
evening peaks.
204 N. 11th Ave., Bozeman, MT 59715 Cell: (406) 581-3319 www.g-e-i.net Page 4 of 4
Summary of Findings
Category Existing 3‐Bedroom SF Home Proposed 6‐Unit Condominium
Water Demand 232 gpd (avg), 84,738 gal (annual) 1,392 gpd (avg), 508,428 gal (annual)
Fire Flow 1,500 gpm for 2 hours 1,500 gpm for 2 hours + Fire Sprinklers
Wastewater Generation 211 gpd (avg), 77,068 gal (annual) 1,253 gpd (avg), 457,585 gal (annual)
Traffic Impact 10 daily trips, 1‐2 peak hour trips 36 daily trips, 4‐5 peak hour trips
Conclusion
The 6‐unit condominium exhibits higher demands in all analyzed categories compared to the single‐
family home. This includes only a 2.3‐fold increase in average domestic water demand when lawn
irrigation is included, no real increase in fire flow requirements other than having a fire suppression
system in the multifamily structure, a 5.9‐fold increase in wastewater generation, and finally only a
3.6‐fold increase in daily traffic trips. These findings highlight the greater infrastructure and
planning considerations that will be part of the site plan development process for this site in
Bozeman, Montana.
If you have any questions or comments, please contact me at 581‐3319.
Sincerely,
__________________
Chris Wasia, P.E.
Genesis Engineering, Inc.
www.g‐e‐i.net
Enclosures
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