SW3210601_SW3200102 Add Info_20201113

ROY COOPER
Governor
MICHAEL S. REGAN
Secretary
BRIAN WRENN
Director
Nicholas R. Parker, PE
7140 Weddington Road, Suite 140
Concord, NC 28027
NORTH CAROLINA
Environmental Quality
November 13, 2020
Subject: Request for Additional Information
Stormwater Permit No. SW3200102
Heilig Road Building Expansion
Rowan County
Dear Mr. Parker:
The Division of Energy, Mineral and Land Resources (DEMLR), received a Stormwater
Management Permit Application for the subject project on October 8, 2020. A review of that
information has determined that the application is not complete. The following information is
needed to continue the stormwater review:
Prior Comment 16 — "Provide pdfs of all revisions, 2 hardcopies of revised plan sheets,
and I hardcopy of other documents. " Please provide hard copies of the revised submittal
materials that were uploaded to Laserfiche in response to the previous Request for
Additional Information letter. The October 8, 2020 hard copy resubmission only included
2x copies of the revised plan set and 2x copies of the revised calculation booklet.
NOTE: If any of the hard copy items from submittal 2 (the prior submittal) are being
modified for submission 3 (the next submittal) then only the most recent version of the
updated item needs to be submitted.
2. Prior Comment 10 — "Please provide a site -specific soils report showing the Seasonal
High Water Table (SHWT) elevation (Section VI, 9 & Sand Filter MDC 1). " The
provided SHWT letter states that the existing ground surface elevation in the location of
the boring is approximately 811 feet and the boring was conducted to a depth of 4 feet
below the existing grade (to an elevation of approximately 807 feet). Per the plans, the
lowest excavated point of the sand filter is at elevation 808.5 (approximately 1.5 feet of
separation). The required 2-foot vertical separation between the SHWT and lowest point
of the facility has not been demonstrated.
NOTE: The Supplement-EZ Form indicates that the SHWT is at or below elevation 806
feet, but this does not match the provided letter.
D E Q 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 -
Department oEnvironmental Uual� 4� 919.707.9200

3. Prior Comment 12 — "Please provide some information on the spec'd ASTM C144 and
show that it is an equivalent to ASTM C33 (Sand Filter MDC 6). " The Supplement-EZ
Form still includes references to ASTM C144 (See later comment).
4. Based on the provided stage -storage table for the sand filter, the design volume of 4,288
cf would result in a temporary ponding elevation closer to 811.54 feet (811.2 feet is
shown in the calculations & plans). It is a requirement that the first bypass elevation (The
single 6" orifice) be at or above this temporary ponding elevation (per Sand Filter MDC
3).
5. Please correct the following issues with the provided Supplement-EZ Form:
a. Sand Filter Page, "Sand Filter MCD From 02H .1056":
i. VI SHWT elevation (f nsl)" — Ensure that this information matches the
provided SHWT information provided and is at least 2 feet lower than the
lowest point of the sand filter.
ii. V2 Physical... "& "...Ponding depth in the sediment chamber... " — If
these is no permanent pool in the sediment chamber, the ponding depth
and physical depth of the sediment chamber are the same. Since the
bottom of the sediment chamber is at elevation 811 and the maximum
ponding elevation is at elevation 814, these values should be 36 inches.
iii. V2 Physical... "& "...Ponding depth in the sand chamber... " — If these is
no permanent pool in the sand chamber, the ponding depth and physical
depth of the sand chamber are the same. Since the bottom of the sand
chamber is at elevation 810 and the maximum ponding elevation is at
elevation 814, these values should be 48 inches.
iv. V3 Elevation of the bypass device (fmsl)" — Please include this value.
This is the elevation of the lowest bypass weir or orifice. Per the plans,
this value is 811.2 ft.
NOTE: This elevation will probably be changed due to addressing a prior
comment and is provided for illustrative purposes only.
v. V3 Describe the bypass device" —Only the lowest bypass device needs to
be described. If the lowest bypass device is an orifice, the diameter should
be included.
vi. V4 Ponding depth from the top of the sand to the bypass device (ft) " —
This is the vertical distance between the top of the sand layer (810 ft) and
the invert of the lowest bypass device.
vii. V6 Sand specification for sand chamber" -Please show that ASTM C 144
is an equivalent to ASTM C33 or remove the reference.

6. Provide pdfs of all revisions, 2 hardcopies of revised plan sheets, and 1 hardcopy of other
documents. Pdfs must be uploaded using the form at:
https://edocs.deq.nc.gov/Forms/SW Project Submittal
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 December 13, 2020, 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 SW3200102 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 [phone].
Sincerely,
✓_ vl
Jim Farkas
Environmental Engineer
Stormwater Program
cc: Mooresville Regional Office