SW3230802_Response To Comments_20240411

American Engineering
8008 Corporate Center Drive, Suite 110
A
AM E RICAN Charlotte, NC 28226
704.375.2438
Engineering www.american-ea.com
January 11, 2024
North Carolina Department of Environmental Quality
Division of Energy, Mineral & Land Resources
Stormwater Program
512 North Salisbury Street
Raleigh, NC 27699
Subject: Green Acres—SW3230802
Response to Stormwater 15t Review Comments
Dear Ms. Holland,
Please find below the original review comments provided and each subsequent response:
1. Per the deed restrictions, the maximum built-upon area per lot is 3,660 SF for 37 lots. 3,660 SF/lot x 37 lots =
135,420 SF which is less than the 135,428 SF listed in the Application Section IV, 10 and Supplement-EZ Drainage
Areas. Please revise for consistency.
Response: This is a round off error. The difference equates to 0.22 sf per lot. It is not feasible to
restrict the lots down to the hundredth decimal place.
2. Per the USGS map and provided plans, there is a stream within the property boundary. If the project boundary is
the property boundary, please revise Section IV 4-8 accordingly. NOTE: The area in Section IV, 6 should be the
area below the Normal High Water Line (NHWL) per 15A NCAC 02H .1003(1)(c)(i). Surface water area is excluded
from the project area and project density calculation in the Application and Supplement-EZ Form.
Response: The stream is intermittent. The NHWL is not know.The top of bank has been used as the
NHWL. This equates to 1,970 sf(0.045 ac). Sections IV 4-8 have been updated accordingly.
3. Per 15A NCAC 02H .1017(10) a 30 ft vegetated setback is required from the top of bank of each side of streams
(15A NCAC 02H .1003(4)). Please revise the plans and Supplement-EZ, Cover, Line 7 accordingly. It appears that a
rip-rap apron may be proposed within the setback, which does not meet the vegetation requirements.
Response:The 30'vegetative setback has been added to the plans. The riprap apron for the pond
outfall has been shifted out of the vegetative setback.
4. Per the provided Post Development Drainage Area Map, portions of Green Acres Circle are being directed to the
SCM and must be accounted for in the Application, Supplement-EZ, and calculations.
Response: The detained area shown on the Post Development Area Map includes the pavement areas
within Green Acres Circle. The pavement within Green Acres Circle directed to the pond is proposed

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pavement under the category"Roadway Pavement—Curb". The Map has been updated to break out
this BUA in the post-detained areas table.
5. The elevation of the temporary pool is set by the lowest bypass device, which appears to be 655.80 per the
detail on Sheet C4.2, but is listed as 655.68 on the Supplement-EZ.
Response: This is incorrect. The temporary pool is set as the water quality volume stage elevation.
The lowest bypass device is the water quality bleeder set at the permanent pool elevation.
6. Ensure the electronic repository and the hard copies are the same.
Response: Submitted documents will be the same both pard copies and electronic.
7. Please exclude the sediment storage zone from the main pool and forebay volume calculations (Wet Pond MDCs
1, 2, 3, &5) and revise relevant portions of the Supplement-EZ accordingly.
Response: MDC 3 instructs the designer to add six inches of depth (additional)to the pond for
sediment storage. 12" of sediment storage has been added to the pond detail and grading.
Application
8. 2x hard copies of the Application with the following corrections made is required per 15A NC 02H .1042(2)(a)
and per Section VI, 1 of the Application
a. Section IV, 10-The information provided in the Drainage Area 1 Column should correspond to the drainage
area of the SCM provided in the Drainage Area 1 Column of Supplement-EZ and plans.
Response:The data on the application and EZ form have been updated to match.
Supplement-EZ
9. 2x hard copy of the complete, original Supplement-EZ Form is required per Sections V&VI, 3 of the Application
a. Wet Pond, Line 33: Per the Supplement-EZ, Wet Pond, Line 27,the volume of the main permanent pool is
2=98,443 cf. Per the Supplement-EZ, Wet Pond, Line 32, the volume of the forebay is 6,127 cf. 6,127
cf/29,443 cf= 21% (> 20%therefore,the forebay is too large).
Response: The forebay has been resized accordingly.
b. Wet Pond, Line 34: Per the O&M,this value is 3 ft, but it varies in the package.
Response: The forebay has been revised to show 12" sediment storage. The clean out depth will be
48"from the permanent pool to the top of the sediment storage.
c. Wet Pond, Line 35:The design volume is the volume between the temporary pool elevation and the
permanent pool elevation. Please revise.
American Engineering
8008 Corporate Center Drive,Suite 110 1 Charlotte, NC 28226 1 704.375.2438 1 www.american-ea.com

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Response: Please see response to comment#5.This is the Water Quality Volume as well.
d. Wet Pond, Line 37: Please provide.
Response: The bleeder orifice has diameter has been added.
e. Wet Pond, Line 40: Please revise with the correct temporary pool per Comment 5.
Response: Please see response to comments#5.
f. Wet Pond, Line 47:The vegetated shelf must have a maximum slope of 6:1 per 15A NCAC 02H .1053 (6).
Response: The vegetative shelf has been designed to be 6 feet at 6: slope. All forms and plans have
been updated accordingly.
Plans
10. 2x signed &sealed hard copies of a plan sheets showing the following (This item is required per 15A NCAC 02H
.1042(2)(g) and per Section VI, 8 of the Application)
a. Please verify the scale that is listed on the plans. For example,the scale on Sheet C3.0 lists the scale as 1
inch = 200 ft, but when using that scale,the 24' EP-EP dimension measured to approximately 95 ft, and
therefore the BUA listed on the Supplement-EZ and Application could not be verified.
Response: The 1"=200' is for the inset detail only. The overall plan view scale is 1"= 50'as shown on
the graphic scale.
b. Please clearly delineate the project boundary on the plans if it is not the property boundary. Per comment 2.
Response: Please see the Post Development Area Map. This is the project boundary.
c. Provide wetland delineation or a note on the plans stating that there are no wetlands located on-site.This
item is required per 15A NCAC 02H .1042(2)(g)(iii) &Section VI, 8m of the Application. (Must be delineated
by a qualified person. Provide documentation of qualifications and identify the person who made the
determination on the plans.
Response: There are no wetlands on-site except for those shown on the USGS maps. Please see plan
sheet C4.0 for NHWL and existing wetland note.
d. Sheet C4.2- Please provide elevations with a benchmark for clean-out of the wet pond on the plan view or
cross section of the details per 15A NCAC 02H .1042(h)(i). NOTE:The maintenance schedule on this sheet
states "REMOVE SEDIMENT FROM FOREBAY/CHAMBER WHEN MORE THAN 1 FOOT OF STORAGE IS LOST,"
but the O&M manual lists a sediment removal depth of 3 ft for the forebay.The O&M manual states a
sediment storage depth of 4 ft for the main pool. Per the Supplement-EZ,the bottom of the sediment
removal is 647 and the top of sediment removal is 648. Please ensure consistency across package.
American Engineering
8008 Corporate Center Drive,Suite 110 I Charlotte, NC 28226 1704.375.2438 I www.american-ea.com

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Response: The bench mark has been added to the cross section view of the control structure. The
O&M,Supplement-EZ, and plans have been updated to be consistent with sediment clean out depth.
e. The Maintenance Schedule seems to be for a sand filter(references annual inspection of a sand filter, and
raking sand).
Response: We apologize for the mix-up on this. Updated Maintenance schedule has been included
with this submittal.
f. There appears to be grading changes between the hard copies accepted on August 3, 2023 and what was
uploaded electronically on Sheet C4.2. Note that the vegetated shelf must have a maximum slope of 6:1 and
be at least 6 ft wide per 15A NCAC 02H .1053 (6). The slope appears to be steeper close to the bypass.
Response: The electronic and hard copy of the submittal documents are the same for this submittal.
The pond section/profile is derived from the CAD generated design surface. At the control structure,
we need to keep cover on the outfall pipe and ensure the structure is far enough into the pond to
allow the WQ bleeder to function properly. The 6'shelf at 6:1 is maintained throughout the pond
except for the areas immediately next to the control structure. Please refer to the contours on the
plan view. Also,the cross section/profile view is placed to be as close to perpendicular to the bank as
possible. There may be discrepancies at the outfall and control structure. The shelf area has been
added to the plan view for clarity.
g. The riprap apron sizing provided in the calculations does not correspond to the apron size provided on Sheet
C4.2. Inlets, outlets, and receiving streams must be protected against erosion per 15A NCAC 02H .1050 (4).
Response:The riprap apron has been updated to match the calculations.
h. Sheet 4.2 shows an underdrain pipe, please include a valve or alternative method of ensuring this does not
drain the pond unless maintenance is needed.
Response: Valve has been added.
i. The plant schedule needs to refer to the specific plant types in order to ensure compliance with 15A NCAC
02H .1053 (11).
Response:The planting schedule has been updated to include quantity and type of plantings.
j. The dam structure, including front and back embankment slopes, of the pond shall be vegetated with non-
clumping turf grass; trees and woody shrubs shall not be allowed per 15A NCAC 02H .1053 (11)(a), so please
revise the planting plan.
Response: Notes have been added to indicate no trees or shrubs in the embankment area. Note has
been added for non-clumping turf grass on the embankment.
American Engineering
8008 Corporate Center Drive,Suite 110 1 Charlotte, NC 28226 1 704.375.2438 1 www.american-ea.com

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O&M Form
11. 1x original, and 1x hard copy signed & notarized hard copy of the O&M Agreement Form (This item is required
per 15A NCAC 02H .1042(2)(j) and per Sections V&VI, 3 of the Application).
a. Please ensure the electronic repository is complete, currently the O&M manual provided electronically only
includes the cover page.
Response: The complete O&M form has been added to the electronic copy.
b. The sediment removal elevation is intended to be the elevation at which sediment is removed. It appears
that the clean out depth and sediment removal elevation lines need to be exchanged.
Response: The information for the pond elevations and sediment clean out depth has been corrected.
American Engineering
8008 Corporate Center Drive,Suite 110 I Charlotte, NC 28226 1704.375.2438 I www.american-ea.com