SW6220301_Comment Response_20221116

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Project: Long Point Subdivision
Location: Long Point Road, Vass, Moore County
Jurisdiction: NCDEQ
Date: 6/9/22
Subject: SW Comments SW6220301
4006 Barrett Drive, Suite 104
Raleigh, North Carolina. 27609
TEL [phone]
Comment
Response
General Design Comments
Response
- Wet Ponds — As designed, the bypass weirs in the outlet structures
✓
Bypass weir inverts and calculations have been revised.
for both ponds are position in a manner that results in a drawdown
time from the invert of the weir to the invert of the drawdown orifice
Of more than 6 days. This extended drawdown time may kill the
vegetation planted on the vegetated shelf. It is strongly
recommended to lower the inverts of the bypass weir inverts so that
they are closer to the ponding elevation of the design volume
(approximately at elevation 259.8 for wet pond 1 and approximately
at elevation 253.8 for wet pond 2). Strictly speaking, this outlet
configuration is not against the MDCs (since the design volume
draws down to the permanent pool level within the 2-5 day window),
however it is not an ideal configuration (as mentioned, extended
submersion of the plants on the vegetated shelf can be harmful to
them) and the design runs counter to the idea behind Wet Pond MDC
7. You are not required to fix this issue, but it is strongly
recommended to help ensure ongoing functionality of the wet ponds
and reduce maintenance issues.
- Infiltration Basin The bottom of the subgrade sand layer of the
✓
Note has been added and a rate of 6"/hr has been utilized with
infiltration basin (i.e., top of the in -situ soil) is located approximately
a note in the Supplement lbrm stating rate was intentionally
40" below the existing ground surface elevation for the SHWT
lowered to 75% of determined rate to account for clogging of
boring (bottom of the sand layer is at elevation 245 and the existing
the soils that will happen over time.
Cyr ade for soil boring 3 is at elevation 248.3 (248.3 - 40" = 245). Per
the soils report, the infiltration rate for the soils 40-50" below the
existing ground surface elevation (same elevation as the bottom of
the sand layer of the infiltration basin) were not evaluated due to
perched water. Please use the infiltration rate of the next lowest soil
layer (S"/hr) in your calculations. It is recommended to add a note to

Bowman
400h Harretl Drive, Suite 104
Raleigh_ North Carolina 27609
TEL (919) 5i3-6570
the plans indicating that the perched water layer be removed when
encountered and replaced with the sand (in order to ensure adequate
infiltration for this SCM).
✓
Calcidations have been provided-
- General Design — Per General MDC 4, please provide calculations
demonstrating that the inlets and outlets are adequately protected
from erosion.
Response
Supplement EZ Form
Cover Page:
Vegetative setback has been listed.
- Line 7 — Please list the required vegetated setback distance from
surface waters here (it is 30' per 15A NCAC 02H .102](7), but the
water supply watershed may have more stringent requirements. If
they do, please list that value)
Drainage Areas Page:
✓
-Line 9: Item has been revised.
- Line 9 — This item corresponds to the amount of BUA that is
-Line 10: llem has been revised.
allocated to the individual lots. Per the provided deed restriction
-Line 12: Item has been revised.
document, the total amount of BUA allocated to the individual lots is
242,000 sf (it appears as though the BUA allocated to the individual
lots was recorded on the "Roof' portion of Line 12). Please revise.
- Line 10 — This item corresponds to the amount of BUA that is
located in the common areas (not allocated to the individual lots).
The sum of the items listed on Line 12 is equal to Line 10. Please
revise.
- Line 12, Roof - This item corresponds to the amount of roof area
BUA that is located in the common areas (there does not appear to be
any per the plans). Please revise.
Infiltration Page:
✓
-Line 26145: Item has been revised per response above,
- Line 26 & 45 — See earlier comment. If using an infiltration rate
-Line 33: Item has been revised.
different than what is shown in the soils report, please provide an
explanation in the additional information section (Line 46).
- Line 33 — The provided stage -storage table shows that the cross -
sectional area of the infiltration basin at the storage elevation (247.1)
is 12,880 sf (13.240 sf is shown on the form).

Bowman
iv
Vass - Since this project is located in an area with overlapping post -
construction jurisdictions, please make sure that you have reached out to the
local water supply watershed jurisdiction so that they may also review and
approve this project. Please provide some form of proof that the local
jurisdiction is reviewing (or has reviewed) this project If you have not yet
done so, please reach out to the local jurisdiction for review/approval as they
also need to review and approve this project.
✓ I Local jurisdiction has reviewed this project.
4006 Barrett Drive, Suite 104
Raleigh, North Carolina, 27609
TH. [phone]