HomeMy WebLinkAboutDrainage Review 8-2-12
nd
August 2, 2012 2 Submittal
Ms. Janet Reid
GHA Architecture/Development
14110 Dallas Parkway, Suite 100
Dallas, TX 75254
RE: Olive Garden
Michigan Road @ Retail Parkway
Technical Advisory Committee
Engineering Review for Development Drainage Designs
Dear Ms. Reid:
The stormwater review of the proposed construction plans and drainage calculations for the above referenced
project has been completed. The submittal is in need of additional information in order to be in compliance with
the City of Carmel Stormwater Technical Standard Manual (the manual). Please revise the plans in accordance
with the comments below.
1.Per Section 102.02.v.d, please include the FEMA map reference number in all notes about floodplains,
floodway fringes, and floodways.
2.Section 102.02.xi.k., please revise the Grading Plan, Sheet C4.2, and/or Drainage Plan, Sheet C4.3, to
show the emergency flood routing path(s) and their invert elevations from the detention facility to the
receiving system.
3.Per Section 102.02.xi.r., please revise the Grading Plan, Sheet C4.2, and/or Drainage Plan, Sheet C4.3,
to indicate the slopes of all surface drainage swales. The response letter states that all drainage swale
slopes have been added to Sheet C4.2, however the slope of the Southwest pond is not included.
4.Per Sections 102.02.xi.l and 102.02.xi.s., please revise the Grading Plan, Sheet C4.2, and/or Drainage
Plan, Sheet C4.3, to include a typical cross section of the detention pond showing the following
information on the cross sections:
a.10-year high water elevations resulting from the controlled release conditions called for by the
City of Carmel’s Stormwater Management Ordinance
b.Bottom of pond, top of bank, emergency spillway, and water surface over the emergency
spillway elevations
c.Emergency spillway dimensions
5.Section 102.02.xi.o., please revise the plans to include a statement indicating the definition of minimum
flood protection grade in accordance with the manual.
6.Section 102.02.xiv., please include a separate Structure Data Table containing the minimum information
discussed in the manual or revise the Storm Sewer Pipe Analysis on the Storm Sewer Plan, Sheet C4.4,
to include the required information.
7.Per Section 302.06.01, please provide information to verify that a minimum of 90% of the original
detention capacity of the proposed dry detention basin is restored within 48 hours from the start of the
design 100-year storm. It appears that the Northeast Pond does not conform. Please review and revise as
necessary.
8.Per Section 302.08.1, a minimum of 1% bottom slope in all directions shall be provided in dry detention
facilities with perforated subsurface drains. The Southeast pond does not conform to the minimum 1%
bottom slope and the West pond does not have a slope listed in the Construction Plans. Please review
and revise accordingly.
OliveGarden
GHAArchitecture/Development
August2,2012
Page1of2
9.Per Section 302.08.2, the maximum planned depth of stormwater water stored shall not exceed four (4)
feet. Also note that any waiver requests should be submitted directly to the City of Carmel Engineering
Department.
10.Please provide a typical section of the emergency spillway in the Construction Plans and calculations
for the proposed spillway to show that it complies with all requirements of Section 302.11 of the
manual.
11.Per Section 501.01, there should be no less than 2.50 feet of cover along any part of the pipe from final
pavement elevation or final ground surface elevation to the top (outside) of pipe. It appears that there
are multiple storm sewer structures that are not in conformance. Please note that any waiver requests
should be submitted directly to the City of Carmel Engineering Department.
12.Per Section 501.03, a minimum drop of 0.1 feet through manholes and inlet structures shall be provided.
Also per Section 501.03, when changing pipe sizes within a structure, the pipe crowns should align.
Please note that any waiver requests should be submitted directly to the City of Carmel Engineering
Department.
13.Please provide calculations showing that the downstream receiving system from the detention pond
(grate and pipe flow of Existing Storm Structure “A”) is sufficient to convey the peak detention pond
outflow in addition to the watershed already draining to the inlet. Verify that there are no downstream
restrictions, and that the system can handle the emergency overflow scenario. (This information should
be surveyed, as-built information.)
14.Per Section 305.02, the minimum diameter of all storm sewers shall be 12 inches. This shall apply to
both public and private storm piping, unless the piping is a roof drain, footing drain or sump pump.
When the minimum 12-inch diameter pipe will not limit the rate of release to the required amount, the
rate of release for detention storage shall be controlled by an orifice plate or other device, subject to
acceptance of the City of Carmel. Please revise the plans accordingly.
Please include with your submittal, one (1) copy of the comments indicating the action taken or a written
explanation for action not taken.
Construction plans and drainage calculations are not to be re-submitted
without implementing changes with respect to any and all review comments from the City of Carmel and the
Hamilton County Surveyor’s Office.
Please contact me at (317) 780-1555 ext. 112 with any questions.
Sincerely,
CrossRoad Engineers, P.C.
Gregory J. Ilko, P.E.
Project Manager
copy: Gary Duncan, City of Carmel Assistant Engineer
Greg Hoyes, Hamilton County Surveyors Office
John Thomas, City of Carmel MS-4 Operator
Amanda Foley, City of Carmel
File
OliveGarden
GHAArchitecture/Development
August2,2012
Page2of2