SW3190703_NCDEQ Stormwater Permit Comment Response_10/29/2019

LandDesign®
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October 29, 2019
Corey Anen
Environmental Engineer
North Carolina Departments of Environmental Quality
Division of Energy, Mineral & Land Resources Stormwater Program
512 N. Salisbury Street
1612 Mail Service Center
Raleigh, NC 27699-1612
Dear Corey,
Please find the comments and responses for the Stormwater Comments of Hemby Place below:
1. Please update the drainage area table in Part IV of the application to include the receiving stream name,
stream class, and stream index number. This information can be found using the Surface Water Body
Classification Map.
Land Design Response: Drainage Area Table updated to show receiving stream to be Sixmile Creek.
2. This project appears to be in the Sixmile Creek Watershed. Projects in the Sixmile Creek Watershed must
also comply with the stormwater standards that apply to the Goose Creek Watershed (15A NCAC 02B
.0602).
Land Design Response: Project has been designed to meet stormwater standards applying to Goose
Creek Watershed.
3. The plans show surface waters that were not listed in the application in Section IVA. Please estimate the
total area of surface water and subtract it from the project area.
Land Design Response: Revised estimated surface waters to be 0.2 acres, which was subtracted from the
total project area
4. Please add a note to the plans stating who provided the wetland determination.
Land Design Response: Wetland Delineation was completed by RJ Harris, as noted on plans.
5. The applicant (Classica Homes) is listed in the application as the property owner, but the deed states that
the property owner is DeLaney Pecan Grove, LLC. Please explain the discrepancy and make any changes
required to fix it.
Land Design Response: Changed applicant (Classica Homes) from property owner to developer. Classica
will close on property before breaking ground. Updated form with current property owners. There are
three total parcels and six total property owners for the project, so we are currently waiting for signed
project owner authorization to be returned. We have attached the rest of the application and will send the
signature pages as soon as they are received.
Washington DC
223 North Graham Street
Charlotte, NC 28202
Charlotte INC
DallasTX
V: 704.333.0325
F: 704.375.4138
Orlando FL
www.LandDesign.com San Francisco CA

6. Please show a maintenance access and easement to the grading plan that meet the requirements of
General MDCs 8 and 9.
Land Design Response: Maintenance Access and Easement added to grading plan. 10' BMP access
easement provided access from roadway on north side of BMP. BMP Maintenance Easement has been
extended to include entire BMP to toe of slope.
Please make the following updates to the Supplement EZ form:
a. One the "Drainage Areas" sheet, the calculation method (Field 19) should be the calculation method
used to calculate the runoff volume (Simple Method or NRCS Method).
Land Design Response: Corrected calculation method in field 19 to be NRCS Method.
b. The "Design volume of SCM" fields (Sheet "Drainage Areas", Field 18; Sheet Wet Pond" Fields 2 and
35) say 406,742 cf. This number seems erroneous and is not reflected anywhere in the calculations.
For Sheet "Drainage Areas", Field 18 and Sheet "Wet Pond", please list the calculated runoff volume
for the 1" storm and for Sheet "Wet Pond", Field 35 please list the total volume that can be stored
below the detention orifice (Note: we are in the process of updating the Supplement EZ form to clarify
the desired information in these fields).
Land Design Response: Design Volume of SCM was revised. For "Drainage Areas" Field 18 and "Wet
Ponds" Field 2, the value was revised to 50,787 cf. For "Wet Ponds" Field 35, the value was revised
to the total volume stored below the detention orifice, 130,469 cf.
c. Please list the species of turf that will be used on the dam and embankment (Sheet Wet Pond", Field
53).
Land Design Response: The species of turf used for the dam and embankment is FACW Meadow
Mix, from Charlotte -Mecklenburg Seed Mix List Appendix C. The full description of bmp planting is
shown on Sheet C-7.03 "Wetpond Planting Plan."
d. The depth of the forebay at the entrance and exit (Sheet "Wet Pond", Fields 43 and 44, respectively)
are listed as 102 inches and 90 inches, but the plan shows the maximum depth of the forebay as 7
feet. Please revise these fields to match the plans.
Land Design Response: Depth of Forebay was shown as depth to bottom of forebay basin. The fields
have been revised to 84" for both entrance and exit, which is the depth of forebay to sediment storage
elevation.
8. Please update the calculations to use only the main pool and exclude the forebay when calculating the
SA/DA ratio and average depth (Wet Pond MDC 1 and 2).
Land Design Response: Average Depth and SA/DA calculations revised to use only the main pool and
exclude the forebay.
Washington DC
223 North Graham Street
Charlotte, NC 28202
Charlotte INC
DallasTX
V: 704.333.0325
F. 704.375.4138
Orlando FL
www.LandDesign.com San Francisco CA

9. Please use the orifice equation as outlined in Part B of the Stormwater Design Manual when calculating
the drawdown time, using an average head of HO/3.
Land Design Response: Revised drawdown time equation to use average head of HO/3. Changed water
quality orifice size from 3" to 2.5" to meet 2-5 day drawdown requirements.
10. How was the temporary pool elevation for the wet ponds calculated? The temporary pool elevation should
be the storage elevation of the water quality volume assuming no outflow from the wet pond.
Land Design Response: Our temporary pool elevation is calculated using the water quality volume from
the 1" storm. However, the pond is designed with a water quality orifice designed to detain, treat, and
release some of this runoff. Therefore, our calculations show the temporary pool elevation to be the
storage elevation of the water quality volume, 783.71.
Should you have any questions or need any additional information, please contact me at [phone]. Thank you.
Sincerely,
Dale Stewart
Washington DC
223 North Graham Street
Charlotte, NC 28202
Charlotte INC
DallasTX
V: 704.333.0325
F. 704.375.4138
Orlando FL
www.LandDesign.com San Francisco CA