HomeMy WebLinkAboutEngineering Memo Response Letter LAND SURVIEYIN
January 3, 2022
City of Bozeman Engineering Dept.
Attn: Cody Hammond
20 E. Olive Street
P.O. Box 1230
Bozeman, MT 59771-1230
RE: Oak & Cottonwood Apartments, Master Site Plan Review Application No. 20433
Dear Cody,
The following is a transcription of the November 18th Engineering Review Memorandum along
with written responses (in italics) to each item.
1. Sewer and Water Pipeline and Access Easement-The applicant must revise the
easement area to include the additional water main alignment necessary to meet the
looping requirement.
The easement documents have been updated to include the additional water main
necessary to meet the looping requirement.
2. DSSP Section III V(D) (5) Easements - No permanent structures shall be placed within a
utility easement unless an encroachment permit has been obtained. Trees or other
significant landscaping features shall not be placed within ten (10) feet of any utility
main or service lines.
a. The dumpster enclosures by Buildings 2 and 5 are inside the utility easement and
within ten feet of the water and sewer mains.
b. Trees are proposed to be within ten feet of the water main stub from
Cottonwood Road.
The water and sewer main alignments and corresponding easements have been shifted
to provide 10 feet of separation with permanent structures and significant landscape
features.
3. BMC 38.410.060 (C) Private Utility Easement— Utility easements for the benefit of all
utility companies must use the City's utility easement template and name the City of
Bozeman as the Grantee. The City's utility easement template is attached.
T: 406.581.4097 1 E: MCOTTERMAN@CADDISENG.COM PO BOX 11805,BOZEMAN, MT 59719 WWW.CADDISENG.COM
The Public Utility Easement documents have been updated to reflect the latest utility
layout with the City's easement template.
1. DSSP II (A) (3)- Pond inlet and outlet piping shall be protected and designed to prevent
erosion (i.e. splash pads, rip rap, etc.).
a. The applicant must provide outlet protection for all pipes entering the
subdivision ponds from the site.
Rip-rap call outs have been added to the pipe outlets for all pipes entering the
subdivision ponds from the site. A rip-rap detail has been added to Sheet C1.3.
2. DSSP Section 11.6-The applicant must provide a storm drainage plan that includes all
the required elements of DSSP Section II.B. The submitted storm drainage plan does not
present enough information to complete review of the stormwater design.
a. In addition to the elements specified in DSSP Section 11.13, the applicant must
address the following:
i. The applicant must demonstrate the adequacy of all conveyance infrastructure.
1. The applicant has not provided evidence that the swales in Drainage Areas 2 and 4 will
adequately convey the 25-year storm.
Swale capacity calculation have been added to the stormwater section of the Design
Report. The proposed swales will adequately convey the 25-year storm.
ii. The applicant must provide details for the swales and outlet protection.
Rip-rap details and swale details have been added to Sheet C1.3.
3. DSSP Section 11.13.5—The applicant must include all the elements indicated in DSSP
Section II.B.5 in the Storm Drainage Facility Maintenance Plan for all the stormwater
infrastructure on site.
a. The applicant must include the maintenance requirements for the inlets, piping,
and swales in the Storm Drainage Facility Maintenance Plan.
The Storm Water Maintenance Plan has been revised to include additional maintenance
requirements for inlets, piping & swales.
4. DSSP Section II (A)(4) Water Quality-The applicant must include a drainage plan with
post-construction storm water management controls that are designed to infiltrate,
evapotranspire, and/or capture for reuse the post-construction runoff generated from
the first 0.5 inches of rainfall from a 24-hour storm preceded by 48 hours of no
measurable precipitation. For projects that cannot meet 100% of the runoff reduction
requirement, the remainder of the runoff from the first 0.5 inches of rainfall must be
either: a. Treated onsite using post-construction storm water management control(s)
expected to remove 80 percent total suspended solids (TSS); b. Managed offsite within
the same sub-watershed using post-construction storm water management control(s)
that are designed to infiltrate, evapotranspire, and/or capture for reuse; or c. Treated
offsite within the same subwatershed using post-construction storm water management
control(s) expected to remove 80 percent TSS.
a. The subdivision drainage design does not address the water quality requirement
above. The applicant has demonstrated in the drainage report that the
subdivision ponds do not meet the water quality requirement. The applicant
must demonstrate that the site storm drainage design accounts for the
inadequacy of the subdivision design and accounts for the added water quality
runoff from the developed site.
b. The applicant must demonstrate that the site drainage design meets the water
quality requirement and that the required storage volume is routed through the
onsite drainage basins in site Drainage Areas 1 and 2.
Calculations are provided in the storm water design report showing that the
combination of the proposed on-site ponds and existing subdivision ponds have capacity
to capture the first 0.5 inches of rainfall from a 24-hour storm.
5. The subdivision stormwater ponds north of the development are in a degraded state
and no longer provide the designed capacity. The applicant has the following options to
demonstrate that adequate capacity is available in the subdivision ponds for the site
drainage design.
a. The applicant restores the subdivision ponds to the original design as part of the
master site plan.
b. The applicant addresses all the stormwater requirements onsite.
c. The applicant demonstrates the capacity currently available in the subdivision
ponds and revises the site's drainage design to account for any lost capacity.
The applicant is currently working with the Flanders Creek Subdivision Homeowners
Association to participate in rehabilitation of the subdivision ponds. The notes have
been added to the site plans specifying that the existing ponds are to be restore to the
original design volume prior to site paving.
1. DSSP Section (V) (A) (5) Main Extensions-All main extensions shall be looped, where
possible. The water main can be connected to the water main stub coming off of
Cottonwood Road. Two connections will allow isolation if repairs need to be made on a
section of main. The current design does not allow for that redundancy with the single
connection to Flanders Way.
The water main alignment has been revised to connect at Cottonwood Road and
Flanders Way providing a looped system.
2. BMC 38.410.070-The applicant must show all curb boxes at the easement line on the
site plan.
a. The curb stop for Building 3 must be at the easement line.
The site plan has been updated to show curb boxes at the sewer and water pipeline and
access easement line.
3. DSSP Section (V) (A) Main Size -A water design report must be prepared by a
professional engineer for the proposed project. The water distribution system must be
designed to meet the maximum day demand plus fire flow and the peak hour demand.
a. The applicant must demonstrate in the design report that the proposed water
system will meet the sizing requirements of this section.
Fire hydrant pressure and flow data was obtained from the City of Bozeman Water
Department and the results were used to generate a model of the existing and proposed
water system. Water model inputs and results are now included within the attached
infrastructure design report.
CONDITIONS OF APPROVAL:
1. BMC 38.410.060 (C) -The applicant must provide correspondence from NorthWestern
Energy indicating if the existing lighting easement along the boundary of Lots 4 and 5 is
necessary.
a. The applicant stated the NorthWestern Energy indicated the easement was no
longer necessary but the applicant did not provide the correspondence from
Northwestern Energy. The applicant must provide the applicable
correspondence from NorthWestern Energy.
Attached is email correspondence from Jacob Farwell, the project engineer from
Northwestern Energy, stating the they would approve the removal of the easement and
it would not conflict with the current utility plan.
2. The revised Waiver of Right to Protest Creation of Special Improvement Districts (SID's)
is acceptable. The applicant must provide a copy of the recorded SID waiver prior to
master site plan approval.
Acknowledged, the waiver of right to protest creation of SID's will be recorded prior to
master site plan approval.
Please don't hesitate to contact me if you have any questions or need any additional information
to complete your review of this project.
Sincere)
Mat 46t "r n, E:, P.L.S
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