SW6240203_Response To Comments_20240511

INNER BANKS ENGINEERING, PC
5/11/24
Jim Farkas
1612 Mail Service Center
Raleigh,NC 27699-1612
Re: RAI— SW 6240203
Harbor Freight—Erwin
Harnett County
Dear Jim,
Please find our comments to the review you provided to us via email dated 5/10/2024.
1. There appears to be a property area mismatch in the submittal items. Per the
Supplement-EZ Form, the sum of the drainage area to the SCM (48,269 sf) and the low-
density drainage area (18,215 sf), which compromise the entire project area, equals
1.53 ac whereas the project area is shown elsewhere in the submittal items as 1.56 ac.
Please
revise as needed.
The total property area has been modified to 1.526 ac which is
indicated on the final plat for the project area
2. As shown, the low-density area exceeds 24% BUA (4,607 sf / 18,215 sf = 25.3%).
Please revise as needed. NOTE: Is it not possible to capture most of the uncaptured
parking area and direct it to the SCM (like as shown in the attached image)?
The site has been regraded to provide additional area of green space
to the low density area. The revised numbers are Low Density Area
of 18,338 sf and High Density Area of 48146sf. The total impervious
area within the Low Density Area is 4398 sf. This calculates to 23.9%
impervious within the low density area and therefore meets the
requirements.
3. In the provided calculations, the BUA within the drainage area to the SCM is shown to
be39,824 sf and it appears that this is shown being equal to 1.02 ac (it is actually equal
to0.91 ac). Please revise as needed. NOTE: For ease of readability, you may wish to
include units in your calculations.
The calculations for the SCM design have been modified per the
revised areas. This revised Calculation sheet has been included in
the revisions.
P 0 Box 154 Washington, NC 27889 -252.945.2983 [e-mail]

NCDEQ SW 6240203 - Farkas
5/11/24
4. Please date your plans. Plans are required to be signed, sealed, and dated per 15A
NCACO2H .1042(2)(g).
All Plan sheets have been dated.
5. There appears to be an inconsistency in the sand filter cross-sectional view. The
bottom of the SCM is shown to be at elevation 190.0', above that is shown 6" of stone
(190.0' +6" = 190.5'), and above that is shown 18" of sand (190.5' + 18" = 192.0'). The
detail shows the top elevation of the sand layer at elevation 191.5'. Please revise as
needed.
The cross section view has been updated to reflect changes as
noted.
6. There appears to be an inconsistency in the outlet structure note on the plan view of
the SCM. The note indicates that the weir invert is at elevation 67' and the rim is at
elevation 70.5'. Please revise as needed.
The cross section view has been updated to reflect changes as
noted.
7. There appears to be an inconsistency in the underdrain configuration as shown in the
plan view and detail plan view. Please revise as needed.
The cross section view has been updated to reflect changes as
noted.
8. Please provide an existing ground surface elevation for the SHWT boring so the SHWT
elevation can be determined. The boring indicates the depth from the existing ground
surface elevation to the SHWT, but without the existing ground surface elevation, we
cannot determine the elevation of the SHWT. Please revise as needed.
Per the soils evaluation report the Bore location was taken in an area
which the existing elevation is approximately 193.5'. The depth to
the SHWT is 42" so the SHWT elevation is approximately 190.0. This
has been shown on the plan as well as shown on the cross section
of the sand filter. Due to the min. 2' depth to the SHWT an enclosed
sand filter has been designed with water stops to ensure the ground
water does not seep into the SCM as designed.
9. Please correct the following issues with the Application Form:
a. Section I, 4—The provided coordinates do not correspond to the project area. Please
revise as needed. Revised
P 0 Box 154 Washington, NC 27889 - 252.945.2983 - [e-mail]

NCDEQ SW 6240203 - Farkas
5/11/24
b. Section III — Per Harnett County property records, the parcel formerly owned by RUC
Erwin, LLC has been bought by the applicant. Please revise the application to reflect
this.
This has been shown however the closing date for the 2nd parcel will
be completed prior to the issuance of this permit. Please advise how
you would like this information to be shown. At this time Gravity
Companies own a portion of the property along with Shriji
Properties, LLC however in the near future Gravity Companies will
own the entire property.
c. Section III, 2.b. — Please provide an email address for the property owner (for Shriji
Properties, LLC). This item is required per 15A NCAC 02H .1042(2)(a)(ix).
We have been unable to obtain an email address for these owners.
We can provide an email address for the realtor but are unsure if this
is the information you will need.
d. Section IV, 4, 7, 8, & 10- Revise as needed in accordance with earlier comments.
All items have been updated to reflect the changes made per prior
comments.
10. Please correct the following issues with the Supplement-EZ Form:
a. Cover Page:
i. Line 7— Please provide this value per 15A NCAC 02H .1017(10). It is noted that
there are no surface waters located on-site, however we ask that this value be
included.
Noted
b. Drainage Area Page:
i. Revise as needed per earlier comments.
All areas have been updated to reflect the changes made.
c. Sand Filter Page:
i. Line 5 —A vertical wall has a slope of 0:1. lithe cell does not allow you to enter
this value, please indicate that the side slopes are vertical in the additional
information section (Line 43).
Noted
ii. Line 6—The vertical walls of the sand chamber would constitute engineered side
slopes (side slopes steeper than 3:1 are allowed if the slope is engineered).
Noted
P 0 Box 154 Washington, NC 27889 - 252.945.2983 - [e-mail]

NCDEQ SW 6240203 - Farkas
5/11/24
iii. Line 18—See earlier comment with regard to the SHWT elevation. NOTE: The
plans indicate the SHWT elevation is at elevation 189.5' (this item indicates
190.5'). Please revise as needed.
Noted and a bore location has been added to the plans showing the
approximate location of the soil boring for the project.
iv. Line 21— Please provide this value. Since there is no grate proposed in this design,
please indicate the elevation that would allow groundwater to flow into the SCM
(the top of the structure).
Noted, The top of the structure is elevation 195 so this elevation has
been added to the document
v. Line 23— Per the calculations, the volume would be 1,499 cf(999 sf * 1.5 ft =
1,499 cf).
Noted
vi. Line 25 — Per the detail, the bottom elevation of the sediment chamber is shown to
be at elevation 190.0' (189.5' is shown).
The cross section view has been updated to reflect changes as noted.
Changes Made to form
vii. Line 30— Per the calculations, the volume would be 1,499 cf(999 sf * 1.5 ft =
1,499 cf).
Noted
11. As indicated in the 2/19/24 email, please upload the electronic files for this project
to the portal at the following location: https://edocs.deq.nc.gov/Forms/SW-
Supplemental- Upload. Electronic files are required per 15A NCAC 02H .1042(2). NOTE:
When uploading plan sheets, do not upload the entire plan set as a single file, but
rather, upload the sheets individually and specify what type of plan sheet they are.
12. Please provide a Response to Comments letter indicating, in a point-by-point
manner, how each of the above comments has been addressed. This item is required
per 15ANCAC 02H .1042(3)(b).
This document is provided for clarity of each item which has been
addressed.
P 0 Box 154 Washington, NC 27889 - 252.945.2983 - [e-mail]

NCDEQ SW 6240203 - Farkas
5/11/24
Please provide direction for item 9b. Section III of the application, we want to ensure a
complete submittal. We look forward to finalizing this plan and moving forward.
Respectfully,
Inner Banks Engineering, PC
Marie Peedin, PE
P 0 Box 154 Washington, NC 27889 - 252.945.2983 - [e-mail]