HomeMy WebLinkAboutDrainage Reports - 07/19/2024
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MEMO
Date: June 12, 2024
To: City of Fort Collins, Stormwater Engineering and Development Review
From: Shane Boyle, PE
Re: Lee Martinez Farm Tack Shed
Thie memo is intended to document proposed drainage conditions for the proposed tack shed expansion
and sidewalk at Lee Martinez Farm. This project falls under the Planning Minor Amendment process and
consists of an expansion to an existing tack shed building and new sidewalks in order to meet current ADA
requirements. For this project, all work will be completed outside of the existing right-of-way boundary
and all existing buildings will remain. Table A below shows the existing versus proposed impervious areas
for the tack shed project.
Area (Square Feet)
Existing Impervious Area 770
Proposed Impervious Area 1,975
Net Change in Impervious Area 1,205
As seen in the table above, the increase in impervious area is slightly more than 1,000 SF, thus typically
requiring the project to meet the City’s Stormwater requirement for detention and water quality treatment.
However, in this situation, the proposed project is part of a significantly large lot, consisting of
approximately 20 acres of the Lee Martinez Farm and adjacent park and open space. The majority of this
larger area is open space. The proposed increase in impervious area associated with this project will drain
through this undeveloped open space before reaching any downstream body of water. Therefore, our
conclusion is that any increase in runoff volume or rate will be mitigated by the large open space prior to
impacting downstream water bodies. Likewise, this large open space will provide water quality treatment
of the proposed impervious area before discharging to any downstream body of water. Based on these
conclusions, this project requests a waiver from the City’s stormwater requirements as part of the Minor
Amendment.
The total disturbed area onsite is approximately 4,500 SF. This falls under the City’s threshold of 10,000 SF
of disturbed area that would trigger additional Erosion Control Plan and permit requirements. It is expected
that all construction staging and material storage will be accomplished within the construction limits as
shown on the Grading Plan. Should the contractor expand the construction limits beyond those defined
in the Plan, then the contractor would be required to apply for a City Erosion Control Permit at that time.
Please don’t hesitate to reach out should questions arise regarding this Minor Amendment submittal.
City of Fort Collins Approved Plans
Approved by:
Date:
SW-WWW - Matt Simpson
07/19/2024
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Engineer Certification of Drainage Memo
Shane Boyle, P.E.
Registered Professional Engineer
State of Colorado No. 40185
6/12/2024