HomeMy WebLinkAboutCorrespondence: Kimley-Horn MFPG Waiver Request
Suite 2125
205 W. Wacker Drive
Chicago, IL
60606
August 23, 2012
Gary Duncan
Assistant City Engineer, City of Carmel
One Civic Square
Carmel, IN 46032
(317) 571-2441
Re: Olive Garden Restaurant – 10206 Michigan Rd., Carmel IN
MFPG Waiver Request
Dear Mr. Duncan:
Per the City of Carmel Stormwater Technical Standards Manual Section 104.02, “Minimum Flood Protection
Grade [MFPG] of all structures fronting a pond or open ditch shall be no less than 2 feet above any adjacent
100-year local or regional flood elevations” and “The Lowest Adjacent Grade for residential, commercial, or
industrial buildings outside a FEMA or IDNR designated floodplain shall have two feet of freeboard above the
flooding source’s 100-year flood elevation under proposed conditions.” In addition, it has been noted in
review comments from the City of Carmel Engineering Department, that the MFPG must also be two feet
greater than surface water elevation onsite assuming all inlets are plugged.
The proposed development has three proposed detention pond areas, each with overflow weir spillways. The
maximum overflow weir elevation of the ponds is 892.82 (above all the 100-year storm elevations for all the
ponds). The finished floor elevation of the building is 895.05. This provides 2.23 feet of freeboard.
Due to grading constraints of the site, the greatest water elevation onsite is 894.05 assuming all inlets are
plugged. This provides one foot of freeboard to the finished floor elevation of 895.05. Grading constraints
prevent the possibility of lowering this an additional foot. A grading constraint for the site includes
maintaining a minimum four feet of cover over an existing sanitary forcemain that runs through the north side
of the property. Another grading constraint is providing cover over the proposed storm sewer onsite. Lowering
onsite elevations would reduce the cover provided on storm sewer. Additionally, proposed detention pond
elevations and tie elevations to existing grades limit the grading onsite in the parking areas.
While site constraints prevent full compliance of the MFPG City requirement, we are providing over 2 feet of
freeboard from overflow weir elevations and have a minimum 1 foot of freeboard from onsite surface elevations.
Therefore, we respectfully request a waiver of the MFPG requirement.
Please contact me if you have any questions or require any additional information.
Sincerely,
Kimley-Horn and Associates, Inc.
Justin Muller, P.E.
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