SW5210302_Add Info_20210423

ROY COOPER
Governor
DIONNE DELLI-GATTI
Secretary
BRIAN WRENN
Director
Jon D. Frazier, PE
PO BOX 91727
Raleigh, NC 27675
NORTH CAROLINA
Environmental Quality
April 23, 2021
Subject: Request for Additional Information
Stormwater Permit No. SW5210302
Green Hill Subdivision — Phase 1
Franklin County
Dear Mr. Frazier:
The Division of Energy, Mineral and Land Resources (DEMLR), received a Stormwater
Management Permit Application for the subject project on March 15, 2021. A review of that
information has determined that the application is not complete. The following information is
needed to continue the stormwater review:
1. Please clarify the project area for the project currently being permitted (Section IV, 4-8).
a. If the project area for this project will be the bounds of Phase 1 (As shown on
plan sheet C-6) please do the following (It is assumed that this is the preferred
permitting method and later comments will assume that this is chosen, but if it is
not, let me know, I can provide updated comments):
i. Change the title sheet to refer to the current phase being permitted
(Section VI, 8a).
ii. Provide bearings and distances for the extent of the Phase 1 area (Section
VI, 8i).
iii. Revise the drainage area information in Section IV, 10 and the
Supplement-EZ Form. Any portion of the drainage area that is located
outside of the Phase 1 area would be considered "off -site" area. Generally,
having off -site drainage areas should be avoided since, per 15A NCAC
02H .1003(3)(b), the entire off -site drainage area must account for BUA at
its full build -out potential, but since the Applicant also owns the off -site
area and is sizing the SCM for this future off -site BUA this is not an issue
in this case (it just needs to be documented correctly).
iv. The "Entire Site" column of the Drainage Area page of the Supplement-
EZ Form should only show the BUA and area ("drainage area" on the
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 OAROLINA _
Depar ntofEnvimnmmdlDwllry 919.707.9200

form) for the Phase 1 area, not the entire site (More specific Supplement-
EZ Form comments follow).
v. NOTE: When the other phases are ready to be permitted, either this
permit can be modified to accommodate the new phases or new permits
can be applied for and they will reference this permit (and the future/off-
site BUA that this SCM treats).
b. If the project area for this project will be the entire property (Approximately 65
acres) or a portion of the property that includes more than Phase 1, please do the
following:
i. Any BUA that will be built in a future phase should be shown as "Future"
BUA in Section IV, 10 and the Supplement-EZ Form.
ii. Provide bearings and distances for the entire project area (Section VI, 8i).
iii. If the entire site is being permitted now, the proposed BUA that is located
outside of the drainage area to the stormwater wetland will need to drain
to and be treated by an SCM.
2. Please provide an original, signed hard copy of the Operation & Maintenance Agreement
(Section V & Section VI, 3). The electronic copy of the O&M Agreement was reviewed
and found acceptable; however, I did not see a hard copy of the O&M Agreement in the
hard copy submission.
3. Please provide the BUA per lot allocation for the deed restriction document (Section VI,
2 & Section VII). The deed restriction document says, "See attached list", but there is no
attached list. This list is required and is a part of the deed restriction document.
4. Please provide a hard copy of the property deed (Section VI, 10). The electronic copy of
the deed was reviewed and found acceptable; however, I did not see a hard copy of the
property deed in the hard copy submission.
5. Please label the on -site surface area of each surface water (Section VI, 8h). Please also
include Ex. Pond 1 as a surface water since it appears on the latest USGS topographic
map (In accordance with 15A NCAC 02H .1017(10)). Ex. Pond 1 will require a vegetated
setback, this should be shown on the plans (Section VI, 8p).
6. Please dimension all existing and proposed BUA (Section VI, 8j). The information shown
in the Application and Supplement-EZ Forms should be able to be verified on the plans
in the field.
7. Please delineate the drainage area to the proposed stormwater wetland in the main set of
plans (Section VI, 8o). Please also delineate the drainage area to Ex. Pond 2, it appears
that there is some overlap between these two drainage areas. NOTE: The extents of the
drainage area to the proposed stormwater wetland should reflect the current phase of the
project that is being permitted, not the ultimate drainage area extents. What is currently
being permitted must meet all of the requirements as a standalone project (in the event
that the future phases do not get completed).

8. The NRCS Curve Number Method used to determine the design volume is calculated
incorrectly (Calculation guidance is provided in Part B of the Stormwater Design
Manual). The Discrete Curve Number Method requires the runoff volume from the
impervious areas and the pervious areas to be calculated independently and then added
together. If you believe that the runoff volume was correctly calculated, please provide a
map showing the delineation of drainage areas 3S-A & 3S-B. Based on the information
provided in the submission, the runoff volume would be closer to approximately 45,000
cubic feet (The houses/sidewalks/etc... are not considered disconnected impervious
surfaces unless they are designed and permitted as such). The design of the stormwater
wetland was not reviewed for correctness since its sizing was based on an incorrect
design volume. General comments about the stormwater wetland that would apply to a
stormwater wetland of any size that came up during the review are shown below:
a. Please provide a grading table or a "stage -storage" table for the portion of the
stormwater wetland that is located below the permanent pool so the portion of the
stormwater wetland that is located within the different zones can be verified.
b. Based on the provided soils report, the underlying soils appear to be well drained
B soils. You may wish to consider using a different SCM, one that is more well
suited to the site, or adding a liner to ensure that the stormwater wetland stays
wet.
c. Stormwater appears to short-circuit the entire western portion of the SCM,
consider changing the inlet location (Stormwater Wetland MDC 5).
d. The deep pool area adjacent to the outlet should have a ring of "Shallow Water
Area" around it similar to the other deep pools.
e. Add a note stating that the deep pool plantings should not be planted in the deep
pool adjacent to the outlet structure (to prevent clogging).
f. Please provide a detail for the outlet structure showing the trash rack (Stormwater
Wetland MDC 17).
9. The following issues were noted with the Supplement-EZ Form (NOTE: These
comments are assuming that the project area will be the Phase 1 boundary):
a. Cover Page:
i. Line 2 — This value should match the project area in Section IV, 7 of the
Application
ii. Line 7 — This refers to the width of the vegetated setback from any surface
waters that BUA is not allowed to be placed in (Per 15A NCAC
02H .1017(1) & .1003(4). It does not appear that a 124' setback is
provided. Please revise.
b. Drainage Area Page:
i. Entire Site Column:

1. General — This column should refer to the entire project area
(Phase 1).
2. Lines 5 & 6 — These items should equal the project area as shown
in Section IV, 7 of the Application and on the Cover Page of the
Supplement-EZ Form.
3. Line 8 — This item should equal the total amount of BUA that will
be located within the project area (Phase 1) at the completion of
the project.
4. Line 9 — This item should equal the total amount of BUA that will
be added to the individual lots associated with Phase 1 and should
match the information from the deed restriction form.
5. Line 10 — This item is the total amount of BUA that will be added
to the project area (Phase 1) that is located outside of the individual
lots. This value is broken down by type in Line 12.
6. Line 18 — This item should match Section IV, 8 of the Application.
ii. Drainage Area 1 Column:
1. Lines 6 & 7 — The off -site portion of the drainage area is any part
of the drainage area to the stormwater wetland that is located
outside of the project area (Phase 1). The on -site portion of the
drainage area is any part of the drainage area that is located within
the project area.
2. Lines 8 -10 These are BUA accountings for the on -site portions of
the drainage area to the stormwater wetland. If the entire on -site
BUA is directed to the stormwater wetland, Lines 9 & 10 will
equal the values from the entire site column. If there are portions
of the on -site BUA that do not drain to the stormwater wetland,
they will not appear in these items.
3. Line 11 — This item is equal to any off -site BUA, existing and/or
future, that drain to the stormwater wetland from outside of the
project area. Per 15A NCAC 02H .1003(3)(b), this off -site area
must be treated at its full buildout potential.
4. Line 20 — See earlier comment.
c. Stormwater Wetland Page:
i. Line 2 — This item should be based on the design storm (1.0").
ii. Line 18 — This item should be the actual amount of stormwater that can be
stored above the permanent pool and below the lowest bypass elevation
(Weir @ elevation 194.25). This item should be greater than or equal to
Line 2.
iii. Line 37 — The shallow water zone percentage of the total area is less than
35% (6,131 sf / 17,518 sf = 34.998% < 35%). This percentage rounds up
to 35%, but the MDC (Stormwater Wetland MDC 8) requires the
percentage to be between 35% and 45%. I understand that the
functionality of the SCM will not noticeably change by moving a square
foot or two from one zone to another, but those are our rules.
iv. Line 38 — Similar to above, the forebay deep pool percentage of the area is
too large (2,628 sf / 17,518 sf = 15.002% > 15%).

v. Line 39 — Similar to above, the non-forebay deep pool percentage of the
area is too large (2,628 sf / 17,518 sf = 15.002% > 15%).
vi. Line 53 — This item is required.
10. Provide pdfs of all revisions, 2 hardcopies of revised plan sheets, and 1 hardcopy of other
documents.
a. Pdfs must be uploaded using the form at:
https://edocs.deq.nc.gov/Forms/SW—Project Submittal
b. Hard copies must be mailed or delivered to the following address:
Jim Farkas
512 N. Salisbury Street
1612 Mail Service Center
Raleigh, NC 27699-1612
While it is not required, the following items are recommended:
- The permanent drainage swales should have less steep side slopes (ideally 3:1 or flatter).
This will make maintenance easier and will help reduce the possibility of erosion.
- The emergency spillway for Ex. Pond 2 should be reviewed to ensure that it is
sufficiently sized since it appears that the proposed stormwater wetland's emergency
spillway discharges directly to the existing pond.
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 May 23, 2021, 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 SW5210302 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,
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Jim Farkas

Environmental Engineer
Stormwater Program
cc: Raleigh Regional Office