SW3190805_Add Info_20190926

ROY COOPER
Governor
MICHAEL S. REGAN
Secretary
S. DANIEL SMITH
Director
Hy V. Nguyen, PE
420 Hawthorne Lane
Charlotte, NC 28204
NORTH CAROLINA
Environmental Quality
September 26, 2019
Subject: Request for Additional Information
Stormwater Permit No. SW3190805
Village at Granite Quarry — Phase 2
Rowan County
Dear Mr. Nguyen:
The Division of Energy, Mineral and Land Resources (DEMLR), received a Stormwater
Management Permit Application for the subject project on August 27, 2019. A review of that
information has determined that the application is not complete. The following information is
needed to continue the stormwater review:
Please QA/QC your deliverable package prior to resubmission. There were multiple
inconsistencies between the provided calculations, plans, and Supplement-EZ Form that
limited the scope of the review of this submission. A non -exhaustive list of some
examples of these inconsistencies is below:
a. Wet pond drainage area — 22.5 ac. (Supplement-EZ), 26.0 ac. (Calculations)
b. Wet pond BUA— 10.8 ac. (Supplement-EZ), 11.7 ac. (Calculations)
c. Wet pond main pond surface area — 18,000 sf (Supplement-EZ), 16,500 sf
(Calculations)
d. Wet pond main pool volume — 74,500 sf (Supplement-EZ), 71,250 sf
(Calculations)
e. Wet pond vegetated shelf is shown as both 6 ft wide and 10 ft wide on the plans.
f. Etc...
2. The project site is located within 5 miles of Mid -Carolina Regional Airport, RUQ
(Section II, 5).
3. The applicant is the property owner (Section III, 1, c). Please select the appropriate box.
Since the applicant is the property owner, Section III, 2 & Section IX are not needed.
4. Please provide the information for the jurisdiction that will be issuing the building permit
(Section III, 4).
D EQ 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 _
o.PaWnamofEnvironmental Quality /� 919.707.9200

5. Provided description does not match the provided calculations and plans (Section IV, 1).
Please revise.
6. Please provide the river basin that this project is located within (Section IV, 3). The river
basin can be determined from the map at the following link:
https://ncdenr.mgps. arc gis.com/gpps/Publiclnformation/index.html?gppid=ad3 a85a0c6d6
44a0b97cd069db238ac3
7. Please include all surface waters that exist within the property boundaries (Section IV, 6
& Section VI, 8, h). Recalculate Section IV, 7 & 8 as needed.
8. The plans seem to indicate that there are some sections of the SCM drainage areas that
are not located within the property boundaries. These areas should be included in the
Section IV, 10 table under the "Off -site Drainage Area" section.
9. Ensure that the information in the Section IV, 10 table matches the information shown in
the calculations and the Supplement-EZ form.
10. Please provide the original, signed Supplement-EZ form, with drainage area sheet
included (Section V & Section VI, 3). Supplement-EZ Form can be found at the
following link:
https://files.nc. gov/ncdeq/Energy%20Mineral%20and%20Land%20Resources/Stormwate
r/State%20SW%20Supplemental%20Forms/SuppEZ-2018-Version-2.1. Lxlsm
11. Please provide a stormwater narrative (Section VI, 5).
12. Please provide a USGS map indicating the project location (Section VI, 6).
13. Only one copy of the plans was provided. Please provide a second copy of the plans
(Section VI, 8).
14. Please provide documentation of the qualifications and identity of the individual who
made the wetland delineation (Section VI, 8, m).
15. Please show the surface water buffer on the plans (Section VI, 8, p).
16. Please include a soils report indicating the SHWT for the locations selected for SCMs
(Section VI, 9).
17. Please provide a copy of the current property deed (Section VI, 10).
18. Please provide documentation showing that Jeff Webb is a VP within LGI Homes NC —
LLC (Section VI, 11).
19. Per the calculations, about 9 lots do not drain to any SCM. Per the rules, if the Runoff
Treatment Method is being used to address stormwater requirements, all BUA at build-

out must be treated at one or more SCMs. Please provide sufficient stormwater
management.
20. The sand filter and dry pond are two separate SCMs. The sand filter can be designed to
attenuate peak flows, but that does not make it a dry pond. Please correct the submission
so that the dry pond and sand filter are two separate facilities that create a treatment train
(Effluent from the dry pond flows into the sand filter) or remove the dry pond (Note: The
dry pond was not reviewed for compliance as it appeared that the designer's intent was to
design a sand filter for peak attenuation and not a treatment train).
21. Do not estimate the total BUA for the entire project or either of the SCMs, please use
exact figures.
22. The average depth calculation for the main pool of the wet pond appears to be incorrectly
calculated. Please refer to the Manual for average depth calculations. Also, don't forget
that the sediment storage area is not included in this calculation.
23. Please provide a stage -storage table to verify the volume of the forebay.
24. The location of inlets 7-300 & 7-400 with regard to the outlet of the wet pond does not
avoid short circuiting (Wet pond MDC 4).
25. The Supplement-EZ form indicates that the forebay will not be cleaned of sediment,
please correct this as it is MDC 5 for wet ponds.
26. The pond drains too quickly. Please refer to the Manual for acceptable drawdown time
and calculation method (Wet pond MDC 7).
27. Please provide documentation for the proposed fountain (Wet pond MDC 9).
28. Please provide separate stage storage tables for the sediment chamber and the sand
chamber
29. There is insufficient separation from the SHWT for the sand filter (Sand filter MDC 1).
30. Please refer to the Manual for calculating the design volume of a sand filter (Sand filter
MDC 3).
31. The sand filter must be maintained in a manner that results in a drawdown of at least 2
in/hr at the sand surface (Sand filter MDC 8).
32. Side slopes of a facility should not be steeper than 3:1 without providing some sort of
engineered surface or demonstrating that the slopes will remain stable (General MDC 3).
Side slopes below the permanent water surface elevation of the wet pond or filled with
sand in the sand filter may be steeper than 3:1 without providing justification.

33. Please provide calculations showing that the inlets and outlets of SCMs are stable during
the 10-year storm.
34. 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:
hgps://edocs.deq.nc.gov/Forms/SW Project Submittal
While it is not required, it is recommended that:
- The off -site drainage from upstream properties be diverted around the SCMs since the
applicant cannot maintain control over the development of property that they do not own.
- The permeable areas of the drainage area to the sand filter be limited to reduce the
amount of fine particles that will enter the filter.
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 October 26, 2019, 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 SW3190805 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,
)&M"I Jwt�
.
Jim Farkas
Environmental Engineer
Stormwater Program
cc: Mooresville Regional Office