AddInfoRequest2

Energy, Mineral &
Land Resources
ENVIRONMENTAL OUALITY
June 6, 2017
Mr. Robert Cash, PE
Cardno
9800 Southern Pine Blvd., Ste. I
Charlotte, NC 28273
Subject: Request for Additional Information #2
Stormwater Permit No. SW3170304
Addington Crossing Subdivision
Union County
Dear Mr. Cash:
ROY COOPER
Governor
MICHAEL S. REGAN
Secretary
TRACY DAVIS
Director
The Division of Energy, Mineral, and Land Resources (DEMLR), received additional
information for the Stormwater Management Permit Application for the subject project on May
31, 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. Provide the original signed deed restrictions form.
2. Since you are seeking credit in Storm -EZ for the disconnected impervious areas (DIS)
and grass swales, add DIS and grass swales to the O&M Agreement and provide an
original signed form.
3. Submit supplement forms for the DIS and treatment swales. Only the pages for the dry
ponds were submitted.
4. Repeat Comment: Since the project proposes handling runoff predominantly using storm
drainage piping, SCM's, and is not dispersing flow, it must meet all of the high density
requirements and MDC's in the SCM Design Manual. Revise the SCM's to be from the
list of primary SCMs to treat the water quality volume (1"). Dry ponds are secondary
SCM's. Provide supporting calculations for the SCM water quality designs. Even
though you are attempting to use volume matching, all SCMs used for credit in Storm -
EZ must meet all MDC. Provide thefollowing:
a. Supporting calcs for the treatment swales demonstrating all MDC are met.
b. Supporting calcs for DIS demonstrating all MDC are met.
c. Supporting calcs for the dry ponds demonstrating all MDC are met.
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

i. Orifice sizing for draw down for I" storm must be between 2-5 days, not I
day.
ii. Water quality volume calculation for I " storm.
iii. Stage/storage table to show the storage volume of the I " storm.
d. Provide an on-site soils report that demonstrates the SHWT elevation for each
SCM meets the MDC.
5. Revise Storm -EZ as follows:
a. There is some error(s) somewhere in the data entered that is causing the rainfall
fate output errors (#div/0), even though there are DA's with treated outflow (like
dry ponds) and DA's with untreated runoff (like direct release 4). Please call to
discuss.
b. The minimum design storm for this location is P90.
c. The proposed impervious areas on the project data tab need to be broken out in
the categories, buildings/lots, streets, etc.
d. The DA's are not consistent with the DA map for the swales and dry ponds.
e. Only include the project property area in the DA's in Storm -EZ unless off-site
area actually drains into a SCM (doesn't appear to for this project). Revise the
tabs for project data, pre -development, post -development, and stormwater
controls.
f. Revise the SCM tab:
i. DA's that do not have a SCM need to be removed
ii. Treatment swales and DIS should have zero for storage volume since they
don't store runoff (they function only as filters).
iii. DA C proposes swales, so Bypass 1 area does not meet the DIS MDC.
6. Revise the dry pond easements to include the entire dam embankment to the outside toe
of slope.
7. For DIS to be used, the plans need to include a note that gutters shall discharge onto the
ground, and cannot be piped.
8. Due to the nature of the above comments, additional comments may be forthcoming once
revisions are submitted.
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 June 20, 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.
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 reference the State assigned project number SW3170304 on all correspondence. If you
have any questions concerning this matter please feel free to contact me at
Robert.Pattersonkncdenr.gov or [phone].
ec: Mooresville Regional Office
Brian Johnson — CalAtlantic
Sincerely,
Robert D. Patterson, PE
Stormwater Engineer
Stormwater Permitting Program
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