SW5210201_2021-05-10 - Responses to Request for Additional Information_20210510

The Hau Company
Consulting Civil Engineers
May 10, 2021
Mr. Corey Anen
Department of Environmental Quality
512 N. Salisbury Street
1612 Mail Service Center
Raleigh, North Carolina 27699
RE: Request for Additional Information
Stormwater Permit No SW5210201
Essex Townes and Essex Village
Franklin County
We have received request for additional information dated March 4, 2021. Below are the
comments and our responses to the comments.
('nmmant ft1
Please complete the project density field on the application (Part IV.B) and in the table for
Drainage Area 2.
Response: this field has been completed
('nmmant If?
The existing conditions plan (Sheet C1.0) does not include any information for the offsite areas;
however, based on the submitted sheet the project site appears to be at a lower elevation than
the surrounding developments. No information was included in the application (Part IV.11) as to
how it was determined that there is no offsite runoff. Please provide an explanation and/or
verification that there is no offsite runoff.
Response: Part IV.11 of the application has been completed. There is a small amount of offsite
drainage onto this project.
Comment #3
Please submit pre- and post -development drainage area maps. It appears that these were
supposed to be included in Appendix A of the stormwater analysis but were not.
Response: the drainage area maps are included with the report
PO Box 810 / Rolesville, North Carolina 27571 / [phone]

Request for Additional Information May 10, 2021
Essex Townes/Essex Village Page 2 of 3
Comment #4
Please address the following issues regarding the two wet ponds:
a. Please submit stage -storage data for the forebay and main pool below the permanent pool to
verify the ponds are sized properly.
b. Please submit calculations to show that the average depth is between 3 and 8 feet. These
calculations should exclude the forebay and any sediment storage. Note that the average depth
must be calculated using Equation 2 or 3 in Chapter C-3 of the Stormwater Design Manual and is
not equal to the physical depth of the pond.
c. Please provide calculations showing that the forebay volume is 15-20% of the main pool
volume.
Response: pond depth and forebay volume calculations are summarized in the body of the report
and included in appendix D to the report
Comment #5
Please show a maintenance access and easement on the design plans that meets the
requirements of MDC 8 & 9 [15A NCAC 02H .1050(8) & (9)].
Maintenance and access easements are shown and called out on sheets C2.1 of the Essex
Townes plans and C2.1 and C2.2 of the Essex Village plans
Comment #6
Please submit an Operation Maintenance Plan and Agreement that meets the requirements of
General MDC 11 and 12 [15A NCAC 02H .1050(11) & (12), .1042(2)(j)]. The O&M EZ form can be
used to meet this requirement and can be found on the Stormwater Design Manual website.
Response: a draft O&M Agreement is included with the submittal package
Comment #7
Please provide a complete signed and notarized deed restriction form.
Response: this has been included with the submittal package
Comment #8
Please provide calculations showing that the inlets to and outlets from the ponds will not
experience erosion due to the peak flow from the 10-year storm event.
Response: riprap dissipaters are used at each pond inlet and outlet to prevent erosion.
Calculations are summarized in the body of the report and included in appendix F of the report
The Nau Company, PLLC
PO Box 810 / Rolesvil le, North Carolina 27571 / [phone]

Request for Additional Information May 10, 2021
Essex Townes/Essex Village Page 3 of 3
Comment #9
Provide pdfs of all revisions, 2 hardcopies of revised plan sheets, and 1 hardcopy of other
documents. Pdfs must be uploaded using the form at:
https://edocs.deq.nc.gov/Forms/SW_Project_Submittal
Response: these items have been provided as requested
Please let us know if you have any questions and/or require any additional information.
Sincerely,
T4e Nau QT , PLLC
Jon akins,
jeaki @then uco.com
The Nau Company, PLLC
PO Box 810 / RolesviIle, North Carolina 27571 / [phone]