SW6210503_Comment Responses_20210902

August 18, 2021
Jim Farkas
NCDEQ - Stormwater
512 N. Salisbury Street
Raleigh, NC 27699-1612
RE: Townsend Estates Subdivision
Jim;
We are re -submitting the plans for the Townsend Estates subdivision with the comments from
the June 7, 2021 review letter addressed. The comments are addressed as noted below:
1. The project site appears to be located on the left-handed side of Townsend Road when
approaching from Rockfish Road (Section I, 3). Please revise.
Revised
2. Based on the provided USGS topo map, there appears to be a surface water located on the
property, behind lots 29 & 30. Please include the surface area of this surface water
(Section IV, 6), recalculate the project area (Section IV, 7), recalculate the percent
impervious area (Section IV, 8), show the surface water & surface area of the surface
water in the main set of plans (Section VI, 8h), and show the required vegetated setback
from the surface water in the main set of plans (Section VI, 8p).
The site was delineated and the surface water you are referring to is a perennial stream. Its
centerline crosses onto the site at the back of lot 29 and runs parallel with the rear line of the lot
for 24' before it ends. We assume this stream to be 8' wide so the surface water on site is 96 SF
or 0.0022ac, holding to the hundredth of an acre gives 0.00 ac. We entered "0" for the value on
the SWU 101.
3. The percent impervious area for drainage area 1 does not appear to be calculated
correctly (Section IV, 10). Please revise.
Revised
4. The provided deed restriction documents are for a low -density project whereas this
project is a high -density project. Please provide high -density deed restriction documents
(Section VI, 2 & Section VII).
High density deed restriction form included
5. Please ensure that the BUA, both existing and proposed, is dimensioned and the surface
areas are called out in the main set of plans (Section VI, 8j). The areas used in the
Application and the Supplement-EZ Form should be able to be verified from the plan set.
The existing buildings have been labeled on the C1.0 sheet. We have added a line to the site
plan data block showing the maximum impervious per lot. The remainder of the site plan is well
dimensioned.
409 Chicago Drive, Suite 112, Fayetteville, NC 28306
office 1 910-426-6777 fax [phone]
On time, every time. I www.4DsitesoLutions.com

6. Please delineate the drainage area to the proposed wet pond in the main set of plans
(Section VI, 8o).
Sheet C3.1 has been developed to clearly show this information.
7. Since the permittee is the property owner, Section IX is not required. Please revise the
electronic file to remove the signature from this section.
Revised and uploaded
8. Please ensure that the stormwater maintenance access and easements are shown in the
main set of plans (General MDC 8 & 9).
The site plan has been revised to show that the entire lot that the pond is sited on is designated
as the access and maintenance easement.
9. Please include a note on the plans stating that the vegetated shelf must be planted with a
minimum of three different species at a minimum density of 50 plants per 200 sf of shelf
area (Wet Pond MDC 11b). Please also list the surface area of the vegetated shelf and
minimum number of plants to be planted on the vegetated shelf. It is recommended to
included a landscape/planting plan (not just a detail) for the wet pond showing the type,
number, and location of the plants that will be planted on the vegetated shelf.
Sheet C3.0 has been revised to clearly show this information. Note #16 has been added, the
shelf area is listed with leader text that also references the pertinent detail.
10. Please do not include the sediment storage zone (below elevation 201) in the stage storage
tables for the main pool and forebay. These sediment storage zones are provided.
in addition to, not as part of, the main pool and forebay.
These have been corrected and are included in the resubmittal.
11. Please provide the cross -sectional areas of the main pool and forebay at the permanent
pool elevation (205.5). Please also ensure to include the cross-section at the permanent
pool elevation in the temporary storage stage -storage tables.
The site plan now includes the two requested areas; we have also added two lines to the stage -
storage tables so these elevations are reflected.
12. The SA/DA table value appears to be too small. Please ensure that you are using the
correct table value. The SA/DA table can be found in Part C-3 of the Stormwater Design
Manual.
The table value was recomputed to be 1.6229 for an average depth of 3.3' and is reflected in the
calculations.
13. Please correct the following issues with the Supplement-EZ Form:
a. Cover Page:
i. Lines 2 & 4 — Please include the surface water area and adjust the project area
per earlier comments.
Done
ii. Line 7-9 — Please answer/include these items.
Done
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b. Drainage Areas Page:
i. General:
1. The surface area of the proposed wet pond does not need to be
counted as impervious area.
We have had internal discussions concerning this and the water surface of the
pond will generate runoff similar to concrete or pavement. We have decided to
include the surface area of the pond in our on site impervious for this reason.
ii. Entire Site Column:
1. The entire site column should be an accounting of the entire site,
not just the drainage area to the proposed SCM. If there is
proposed BUA that will be constructed within the project area but
will not drain to the proposed SCM, it should be reflected in this
column (in addition to the on -site BUA within the SCM drainage
area). The "drainage area" for this column is the project area and should match
the information in the Application (as should the
BUA).
Understood and updated
2. Lines 19-21 are not required for this column.
Revised
c. Wet Pond Page:
i. Line 12 —This item is required. Please ensure the drainage easement
complies with General MDC 9.
Revised
ii. Line 26 — This value is the cross -sectional area of only the main pool
(not the entire wet pond) at the permanent pool elevation. Please revise
as needed.
Revised
iii. Lines 27, 28, & 32 — Revise as needed per earlier comment.
Revised
14. 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.
Understood
Sincerely,
4D Site Solutions Inc.
Scott Brown, PE
[e-mail]
Enclosure
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