SW3231102_Response To Comments_20240905

RAVIAN
ENGINEERING
September 3, 2024
Jim Farkas
DEMLR Post-Construction Stormwater Program
1612 Mail Service Center
Raleigh, NC 27699-1612
RE: SCM Comments Response—Permit No.SW3231102
Heritage Building Company Site Improvements
200 Peach Orchard Road,Salisbury, NC
COMMENT RESPONSES
1. N/A
2. The primary SCM is the bioretention cell.The secondary SCM is a system of permanent rock checks to treat
runoff prior to coming to the bioretention cell as well as the semi-permeable pavement.Approximately 50%of
the gravel pad is estimated to be subject to vehicular traffic, while the remaining area will serve as storage area
for inventory and will not be subject to frequent vehicular traffic. Essentially,there will be drive aisles for
vehicles, but the remainder will be used to store inventory. Due to this,this area is noted as being semi-
impervious and does not qualify as BUA per NCDEQ Stormwater Design Manual A-4. This section states, "Any
size stone or aggregate used on portions of projects that receive infrequent vehicular traffic may be counted as
pervious". The SuppEZ form has been updated to omit 50%of gravel as BUA in drainage areas noted as 1 and 2.
It is expected that these areas will further provide pretreatment to runoff before infiltrating into the ground or
being routed to the bioretention cell.
3. See below
a. Elevations have been updated to allow for 2' separation
b. Design volume depth is limited to 0.84'<12" max. with grated lid on the precast concrete structure
providing bypass.This design volume is reflected in the "Bioretention Area—10-yr" design calculations
as well as the SuppEZ form, Bioretention Cell, Line 20. Design storm is based on 10-year frequency. A
stage storage table has been provided.
c. Maintenance easement contains entire SCM and will be recorded with the county upon state approval.
4. See below
a. Per 15A NCAC 02H.1017 (10),vegetated setbacks are required if perennial waterbodies or streams are
shown on the most recent version of the soil survey maps by the USDA.There are no waterbodies or
streams noted for the site. Lines 7-9 have been updated to N/A.
b. Please see pervious pavement statement in 2. Although the second area will be increasing some BUA,
the remainder of the pad will provide treatment for the water and allow infiltration.
c. Bioretention Cell Page
i. Shown on C210
ii. Line 20 has been revised. Line 22 previously showed 62,826 CF as the design volume.This is the
total volume of the Bioretention Cell. Line 22 has been updated to 26,470 CF to reflect the
volume noted in the "Bioretention Area—10-yr" design calculations
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RAVIAN
ENGINEERING
iii. Revised
iv. The SuppEZ spreadsheet automatically rounded the 0.55 in/hr previously. The spreadsheet cell
has been modified to correctly display the unrounded value.
v. Revised
vi. Revised
Regards,
Ravian Engineering, LLC
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Darion George, P.E.
E-mail: [e-mail]
Direct: 618-638-4788
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