SW1220701_Add Info_20221018

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ROY COOPER
Governor
ELIZABETH S.BISER
Secretary *Eaf QUAMNVEw x
BRIAN WRENN NORTH CAROLINA
Director Environmental Quality
October 18, 2022
McCutchen Engineering Associates, PC
Attn: J. David McCutchen, PE
898 West Saint John Street
Spartanburg, SC 29301
AND
All About Plumbing
Attn: Caleb Wilson
PO BOX 1041
Hendersonville, NC 28793
Subject: Request for Additional Information
Stormwater Permit No. SWSW1220701
All About Plumbing Building Addition
Henderson County
Dear Mr. McCutchen & Mr. Wilson:
The Division of Energy, Mineral and Land Resources (DEMLR), received a Stormwater
Management Permit Application for the subject project on July 21, 2022. A review of that
information has determined that the application is not complete. The following information is
needed to continue the stormwater review:
1. General Design Comments:
a. General MDC 3 —Per the provided detail on plan sheet C600 (the second one), the
vegetated side slopes of the SCM are shown to have a cross-slope of 2:1 while the MDC
requires the side slopes to be 3:1 or flatter. NOTE: Steeper vegetated side slopes can be
allowed on a case-by-case basis, but this project should be able to accommodate 3:1 or
flatter side slopes.
b. General MDC 4—Please provide calculations showing that the inlets and outlets are
stable/outlet protection is adequately sized.
c. General MDC 6—Please ensure that the SCM has a means of being dewatered. The
Supplement-EZ Form indicates that the SCM will be dewatered using a drawdown
North Carolina Department of Environmental Quality I Division of Energy,Mineral and Land Resources
512 North Salisbury Street 1 1612 Mail Service Center I Raleigh,North Carolina 27699-1612
NORTH CAROLINA _
oepm nt of Environ wUl uwl ry 919.707.9200

orifice, but this drawdown device does not appear to be indicated on the plans. If a tee
with a removable screwcap (or other method) will be added to the underdrain line to
allow for the SCM to be drained, it needs to be indicated on the plans/details.
d. General MDCs 8 & 9—It is noted that the maintenance access/easement is shown on the
plans, however, this easement must not include any slopes steeper than 3:1 (8b), extend
to the nearest public right-of-way (8c), and include the entire SCM footprint (see
guidance under MDC 9 in Part C-0 of the Manual). There is also a proposed fence
located in close proximity to the east side of the SCM which may make it difficult to
access/maintain the SCM from that side.
e. Bioretention MDC 1 —Please provide a SHWT boring so that the elevation of the SHWT
can be determined and the minimum separation verified.
f. Bioretention MDC 6—Please note that the mixture values shown in the Manual (and
reproduced on plan sheet C600 (the second one)) are incorrect. The maximum percent
fines is 10% (15A NCAC 02H .1052(6)(b)) and the maximum percent organics is 10%
(15A NCAC 02H .1052(6)(c)). Sorry for the confusion.
http://reports.oah.state.nc.us/ncac/title%2015a%20-%20environmental%20qualit. /hgpte
r%2002%20-%20environmental%20management/subchapter%20h/15a%20ncac%2002h
%20.1052.pdf
g. Bioretention MDC 10—Please clarify if sod will be used as the vegetation for the SCM.
It is noted that the Supplement-EZ Form indicates that grass will be used, however the
plans are more ambiguous.
2. Application Comments:
a. Section IV, 10—The Drainage Area 1 column in this table is an accounting of the
drainage area to the SCM, not the entire project area. The information in this column
should correspond to the information shown in the DA 1 column of the Drainage Area
Page of the Supplement-EZ Form (See comments below).
3. Supplement-EZ Form Comments:
a. Cover Page:
i. Please include the width of the vegetated setback (per 15A NCAC 02H .1017(10). It
is noted that there are no surface waters located on-site, however this value should be
included on the form (Lines 8 & 9 can be left as "N/a" since there are no surface
waters located on-site).
b. Drainage Area Page:
i. Entire Site Column:
1. Line 12, Parking & Roof—These items should add up to Line 10. Existing BUA
(even if it is changed from one type to another) is already accounted for in Line
15 so it should not also be accounted for with these items.

2. Line 16—This item should not be included since the site was not previously
permitted.
3. Lines 19 & 20—These items are not required for the entire site column.
ii. DA 1 Column:
1. Please complete this column. This column is an accounting of the drainage
area/BUA to the SCM.
2. Lines 5 & 6—These items should correspond to the drainage area of the SCM
(0.94 ac, expressed in square feet).
3. Line 8 —This item is the total amount of BUA located within the SCM drainage
area (0.65 ac, expressed in square feet).
4. Lines 10, 12, & 15 — Similar to above, the BUA within the drainage area to the
SCM should be categorized as either existing BUA (Line 15) or new BUA (Line
10). New BUA should further be broken down by type (Line 12). The sum of the
items of Line 12 should add up to Line 10 and the sum of Line 10 and 15 should
equal Line 8 (for this project).
5. Line 18 —Calculate this value based on the drainage area to the SCM (Line 8/
Line 5).
6. Lines 19-21 —Please include these items
c. Bioretention Page:
i. Line 2— See below optional comment, revise if needed.
ii. Line 5 —As mentioned above, the plans indicate that the vegetated side slopes of the
SCM are 2:1. Please revise as needed.
iii. Line 9—As mentioned above, there does not appear to be a drawdown orifice shown
on the plans. Please revise as needed.
iv. Line 18 —Please provide this value.
v. Line 21 —The plans indicate that the surface area of the bioretention cell (@ elevation
1003') is 3,612 sf(3,890 sf shown). Please revise as needed. Please also ensure that
the forebay area& volume are not included in the bioretention cell surface area&
volume (A forebay is provided in addition to, not as part of, a bioretention cell). Line
22 may need to be adjusted as well.
vi. Line 26—The in-situ soil infiltration rate was not provided (it appears that the shown
value, 3 fps, may refer to the media mix (which does not need to be reported on this
form)). An in-situ soil infiltration rate is only needed if you are proposing to eliminate
the IWS from the design (per Bioretention MDC 4).
vii. Line 31 — See earlier comment, please revise as needed.
4. Optional Comments:
a. Application, Section IV, 8—While not required, you may utilize the methodology
outlined in 15A NCAC 02H .1003(1)(b) to calculate the project density since this project
has Existing BUA [Net Increase in BUA] /([Project Area] — [Existing BUA]).
b. While not required to be addressed, the calculated minimum required design volume may
be larger than it needs to be. Per Part B of the Manual, the Simple Method, or Discrete
NRCS method can be used to calculate the minimum required design volume (The
provided calculations calculates this value as 1.0 inches of rainfall over the entire SCM

drainage area (which is similar to the Simple Method, but is more conservative since it
assumes that the entire 1.0 inches of rainfall will turn into runoff)).
c. While not required, it is recommended to reduce the available storage depth provided in
the bioretention basin. The current configuration provides 4 ft of ponding (basin bottom
is @ elevation 1003' and the top of the embankment is @ elevation 1007'). This may
harm the vegetation due to prolonged inundation during large storm events.
d. While not required, it is recommended to include an emergency spillway for the
bioretention basin so that if the embankment overtops during large storm events (and/or if
the outlet structure gets clogged), it does so nondestructively and in a controlled manner.
5. Provide PDFs of all revisions, 2 hardcopies of revised plan sheets, 1 hardcopy of other
documents, and a response to comments letter briefly describing how the comments have
been addressed.
a. PDFs must be uploaded using the form at: https:,[/edocs.deq.nc.gov/Forms/SW-
Supplemental-Upload
b. Hard copies must be mailed or delivered to the following address:
i. For FedEx/UPS:
Jim Farkas
512 N. Salisbury Street, Office 640E
Raleigh, NC 27604
ii. For USPS:
Jim Farkas
1612 Mail Service Center
Raleigh, NC 27699-1612
iii. Hand Delivery:
Please reach out to me prior to hand delivering a submission to make sure that I
(or someone else in my group) will be able to receive the submission. Do not
leave the package in the foyer with the security guard.
NOTE: Hard copies should not be sent to a Regional Office. Doing so will delay
the review process and the submission package may be lost while being sent from
the Regional Office to me in the Central Office.
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 November 17, 2022, or
the application will be returned as incomplete. The return of a project will necessitate
resubmittal of all required items, including the application fee. Please reference the State
assigned project number SW1220701 on all correspondence.
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.
If you have any questions concerning this matter please feel free to contact me at
[e-mail] or(919) 707-3646.
Sincerely,
V✓vl
Jim Farkas
Environmental Engineer
Stormwater Program
cc: Asheville Regional Office