HomeMy WebLinkAboutCarmel Midtown Drainage Waiver Request
kimley-horn.com 250 East 96th Street, Suite 580, Indianapolis, IN 46240 317 218 9560
February 20, 2023
Mr. John Thomas
City of Carmel Engineering Department
RE: Carmel Midtown Development Parcel A – Drainage Waiver Requests
Members of the Board,
On behalf of our Client, we respectfully request waiver from the following Drainage Standards.
1. §303.06.02 & §303.07 – The Lowest Adjacent Grade for all residential, commercial, or
industrial buildings shall be set a minimum of 2 feet above the highest noted overflow
path/ponding elevation across the property frontage. All buildings shall have a minimum
flood protection grade shown on the secondary plat. Minimum Flood Protection Grade 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, whichever is greater, for all windows, doors, pipe
entrances, window wells, and any other structure member where floodwaters can enter a
building.
We are requesting that the MFPG (minimum flood protection grade) and MLAG (minimum
lowest adjacent grade) be 4.5” above local flood source.
2. §501.01 – There should be no less than 2.5 feet of cover along any part of the pipe from
final pavement elevation or final ground surface elevation to the top of the pipe.
We are requesting a waiver for the above referenced requirement for pipes D41-D40, D34-
D33, D33-D32, and D32-D31. Minimum cover as dictated by §501.01 cannot be met due to
existing site constraints.
3. §303.06.11 – Detention basins shall be designed with additional ten (10) percent of available
capacity to allow for sediment accumulations resulting from development and to permit the
pond to function for reasonable periods between cleanings.
We are requesting a waiver for the above referenced requirement as the provided
hydrodynamic separators and detention treatment rows will reduce sediment accumulation
within detention chambers.
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kimley-horn.com 250 East 96th Street, Suite 580, Indianapolis, IN 46240 317 218 9560
4. §303.06.12 – Detention basins shall be sized to detain the runoff from the fully developed
right-of-way per the City of Carmel 20-year Thoroughfare Plan across all frontages,
regardless of existing watershed boundaries or drainage breaks/divides.
We are requesting a waiver for the above referenced requirement to permit additional
storm sewer inlet(s) within Industrial Drive to connect directly to existing storm sewer
infrastructure within Industrial Drive. These inlets will not route through proposed
detention or water quality treatment prior to connecting to the existing storm sewer
infrastructure. The site detention has been sized to meet the 1/2 ROW design standard per
the above reference requirement.
If you have any questions, please do not hesitate to contact me at (317) 218-9560 or
connor.strege@kimley-horn.com.
Sincerely,
Connor Strege, P.E.
Project Engineer