HomeMy WebLinkAboutsW3170305_Add Info Request_20170404Energy, Mineral &
Land Resources
ENVIRONMENTAL OUALITY
April 4, 2017
Mr. Patrick Murphy, PE
R. Joe Harris & Associates, Inc.
127 Ben Casey Dr., Ste. 101
Fort Mill, SC 29708
Subject: Request for Additional Information
Stormwater Permit No. SW3170305
Larkin Multi -Family Development
Iredell County
Dear Mr. Murphy:
ROY COOPER
Governor
MICHAEL S. REGAN
Secretary
TRACY DAVIS
Director
The Division of Energy, Mineral and Land Resources (DEMLR), received a Stormwater
Management Permit Application for the subject project on March 27, 2017. A preliminary
review of that information has determined that the application is not complete. The following
information is needed to continue the stormwater review:
1. All SCMs must comply with all MDC in 15A NCAC 02H.1000 and the latest SCM
Design Manual.
2. The person signing the application and O&M agreement must be an officer of the
corporation listed on the NC Sec. of State's website. Or provide a signed letter from one
the officers listed giving Michael Foess signature authority.
3. The rules require the runoff from all BUA to be treated. As currently proposed,
approximately 20% of the roof areas is not being treated in a SCM. Evaluate adding
piping and/or swales to capture the rear roof areas on lots 2, 3, 14-17, 19, 20, and 25-29.
4. Where does the roadside ditch along Amity Hill Road, where the wet pond discharges,
drain to? Does it drain to Third Creek, or Duck Creek to the south?
5. Provide signed and notarized O&M Agreements for the SCMs (General MDC 11). The
new O&M EZ form is available on our website:
https:Hdeq.nc. gov/about/divisions/energy-mineral-land-resources/energy-mineral-land-
permit-,guidance/stormwater-bmp-manual
Nothing Compares,
SState of North Carolina I Environmental Quality I Energy, Mineral and Land Resources
512 N. Salisbury Street 11612 Mail Service Center Raleigh, North Carolina 27699-1612
919 707 9200
6. Please consider using the discrete SCS method or Simple Method for calculating the
WQV. Using composite CN will yield an artificially lower volume. General MDC 1
requires a sufficient sized SCM. See also Part B of the SCM Manual
https://deq.nc. gov/about/divisions/energy-mineral-land-resources/energy-mineral-land-
permit-guidance/stormwater-bmp-manual
7. The DA and BUA is not consistently shown between SWU-101, Sht. Post DA, and the
supplement forms. Revise so all are consistent.
8. Note there are new supplement forms using Supplement EZ found on our website:
https:Hdeq.nc. gov/about/divisions/energy-mineral-land-resources/energy-mineral-land-
permit-guidance/stormwater-bmp-manual
9. All 3 SCMs:
a. The CN is not consistent between Slit. Post DA and the calcs.
b. Provide supporting calcs. for the WQV based on the 1" design rainfall depth.
(General MDC 1)
c. Extend the SCM easements to the nearest public RoW. (General MDC 8)
10. Wet Pond #100:
a. Provide supporting calcs. for the surface area using SADA tables or HRT method
in MDC 1
b. Provide supporting calcs. for the main pool depth using option 1 or 2 in MDC3
c. Provide supporting calcs. for the forebay size (MDC 5)
d. Provide supporting calcs. demonstrating the WQV draws down in 2-5 days (MDC
7)
e. Add contours to Slit. BMP -2 to show the actual excavated depth for the sediment
storage. Also add the elevation to the profile of the bottom of the sediment
storage.
11. Both Sand Filters:
a. Provide a soils report for the SHWT elevation for each sand filter. This must be
based on an in-situ soils evaluation. (MDC 1)
b. Provide a mechanism to evenly distribute flow over the sand surface (MDC 5)
c. Specify on Slits. BMP -4 and BMP -5 that ASTM C33 or equivalent sand must be
used (MDC 6)
d. Revise the stage storage tables to show the cumulative volume at the design WQV
elevation.
e. Revise the stage storage tables to breakdown the areas, stage, and volumes for
each the sediment chambers and the sand chambers.
12. Sand Filter #200:
a. Open sand filters require 2' of separation from SHWT elevation to the bottom of
the sand layer (MDC 1). The supplement form states there is negative separation.
b. The elevations are not consistent between the supplement form and the plans.
Nothing Compares—.__.
State of North Carolina Environmental Quality Energy, Mineral and land Resources
512N. Salisbury Street 1612 Mail Service Center Raleigh, North Carolina 27699-1612
919 707 9200
Please note that this request for additional information is in response to a preliminary review.
The requested information should be received by this Office prior to April 27, 2017, or the
application will be returned as incomplete. The return of a project will necessitate resubmittal of
all required items, including the application fee.
If you need additional time to submit the information, please submit your request for a time
extension to the Division at the contact below. The request must indicate the date by which you
expect to submit the required information. The Division is allowed 90 days from the receipt of
a completed application to issue the permit.
The construction of any impervious surfaces, other than a construction entrance under an
approved Sedimentation Erosion Control Plan, is a violation of NCGS 143-215.1 and is subject
to enforcement action pursuant to NCGS 143-215.6A.
Please reference the State assigned project number SW3170305 on all correspondence. If you
have any questions concerning this matter please feel free to contact me at
Robert.Pattersongncdenr.gov or (919) 807-6369.
Sincerely,
P 2��
Robert D. Patterson, PE
Stormwater Engineer
Stormwater Permitting Program
ec: Mooresville Regional Office
Michael Foess — Dependable Development, Inc.
Nothing Compares --,-,,-
State of North Carolina Environmental Quality Energy, Mineral and land Resources
512N. Salisbury Street 1612 Mail Service Center Raleigh, North Carolina 27699-1612
919 707 9200