SW5230802_Response To Comments_20240612

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ENGINEERING & ENVIRONMENTAL SCIENCE COMPANY
3008 ANDERSON DRIVE,SUITE 102
RALEIGH,NC 27609
[phone]
LETTER ®I' TRANSMITTAL
Date: June 11, 2024
To: Mr. Jim Farkas
NCDEQ-DEMLR,Raleigh Regional Office
3800 Barrett Drive
Raleigh,NC 27609
From: Robert W. Brantly,P.E.
Engineering and Environmental Science Company (E2S)
3008 Anderson Dr., Suite 102
Raleigh, NC 27609
[e-mail]
Subject: Chatham Habitat for Humanity Townhouse Development
Stormwater Permit No. SW5230802
TBD Craft Lane
Siler City,NC 27344
Chatham County
The following are submitted for the above referenced project:
-Two (2) original copies of the revised Stormwater Management Application Form
-Two (2) hard copies of the signed/notarized Low Density Deed Restrictions and
Protective Convenances document.
-Two (2) sets of revised 24"x36"plans and specifications
-Revised O&M Agreement and Supplemental Forms
-Stormwater Evaluation and Calculations
-Secretary of State Documentation for Registered Agent(Anna Spears Tuell)
This project has had two (2) previous submittals. The first submittal was for 'Low
Density'. The project was then revised and re-submitted as 'High Density'.
This current 3'd submittal is to permit the project as 'Low Density'. The following
responses are based on the 1st review comments dated November 3, 2023.

1. As designed, the proposed project will not meet all of the requirements for a low-
density project upon completion:
a. 15A NCAC 02H.1003(2)(b)— The proposed design does not maximize dispersed
flow through vegetated areas/minimize the channelization offlow. There is a
difference between designing a project to maximize dispersed flow through vegetated
areas and designing a project and then maximizing dispersed flow through vegetated
areas. Most all of the runoff from the project is directed towards and concentrated at a
single point, the dry detention basin. Typically,projects that utilize an SCM for
stormwater management are permitted as high-density projects, even if the percent
BUA for the site is below the low-density threshold. A low-density project would be
designed so that most, if not all of the runoff from proposed BUA is allowed to sheet
flow across vegetated areas as dispersed flow.
Revisions have been made since the 1st Submittal, to come into compliance with
requirements for `Low Density' permitting per 15A NCAC 02H .1003(2).
The proposed impervious/BUA at the site will be less than 24%. Runoff will
generally be conveyed by vegetated swales and sheet flow over vegetated areas. No
non-vegetated (rip-rap) swales are now proposed for this project.
To comply with stormwater ordinances reviewed and enforced by the local
jurisdiction (Town of Slier City), a runoff detention area with sufficient storage to
meet these local requirements is provided on-site. Please note that this is not a state
required SCM, and is only being installed to meet local jurisdiction requirements.
Discharge from the detention area will be to a wide vegetated area, which will allow
all runoff from the site to be conveyed off-site via dispersed flow over vegetated
areas. A minimum 30' vegetated area will be provided between the detention area
discharge and the property line.
b. This project proposes an excessive amount of nonvegetated conveyances. Channels
that are lined with riprap do not count as vegetated conveyances as riprap is not
vegetation. The plans also indicate runs of piping in the front and side yards of the
proposed townhomes. Using a culvert to transport stormwater runoff underneath the
townhouses would be an acceptable use of piping for a low-density project, but having
the inlets and run of piping as shown on the plans would not be as it is excessive and
avoidable. Please revise as needed.
No swales/conveyances with rip-rap are proposed for the revised design of the
project.All swales/conveyances are vegetated. The piping in front of the townhomes
has been removed from the plans.
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2. Please provide official documentation showing that the Applicant is in good standing
with the North Carolina Secretary of State and showing the title and position of the
signing official (Harvey Harman) as required per 15A NCAC 02H .1042(2)(b). If Mr.
Harman does not meet the signing official requirements outlined in 15A NCAC 02H
.1040(1),you will either need to change the signing official to someone who is or provide
authorization for Mr. Harman to sign on behalf of the applicant form someone who is.
The signing official has been changed to Ms. Anna Tuell, Finance and Development
Director. Information from the Secretary of State website is provided, and Anna
Spears Tuell is the registered agent.
3. Please correct the following issues with the plans:
a. Please show the drainage areas to the proposed swales. This item is required per 15A
NCAC 02H.1042(2)(g)(iv) and Section VI,8o of the Application.
Drainage areas for the proposed swales are delineated and provided as part of the
submitted plans (Sheet 3B).
b. Please provide a cross-section detail for the proposed swales and specify the type of
lining that will be used for the proposed swales. This item is required per 15A NCAC
02H .1042(3)(b) and Section VI,81 of the Application. Please note that the calculations
for the swales should reflect the swales in their permanent design configuration (if
temporary E&SC matting is used, it should not be reflected in the permanent design
calculations).
A cross-section detail for the swales is provided on the submitted plan drawings.
The swales will have temporary E&SC matting, but the permanent design
calculations are also provided, for when the swales are established and
vegetated/grassed.
4. Please correct the following issues with the calculations:
a. Please use NOAA Atlas 14 rainfall data (https://hdsc.nws.noaa.gov/pfds/?bkmrk=nc)
for determining the 10-year storm flowrates for the proposed swales.
The rainfall data for the swale design has been revised to reflect the NOAA Atlas 14
rainfall data.
b. Please provide calculations showing that the stormwater outlets are stable in
accordance with 15A NCAC 02H.1003(5). •
Figure 8.06.3. from the NCDEQ Erosion Control Manual is provided in the
Stormwater Evaluation and Calculations.
c. When determining the percent BUA for a site with existing BUA, the following
method is used: [Net Increase in BUA]/([Total Project Area]—[Existing BUAJ). If
the existing BUA for the site is 3,280 sf, the net increase in BUA is 25,303 sf, and the
project area is 135,907 sf, this would result in a percent BUA of about 19% (25,303 sf
/(135,907 sf—3,280 sf) = 19.1%). Please revise as needed.
The percent BUA has been revised in the application.
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5. Please correct the following issues with the Application Form:
a. Section IV, 10—Please only list one column per permitted drainage area. This project
only has one permitted drainage area, the low-density area.
This Section has been revised as requested.
b. Section IV, 10, Onsite Buildings/Lots—For a subdivision project like this one, this
value corresponds to the BUA allocated to the individual lots (not just the buildings
on the lots). Please revise as needed. The information in this column should
correspond to the low-density column of the Supplement-EZ Form.
The Application and Supplement-EZ Form have been revised.
c. Section IV, 11 —This section is only required if there are off-site portions to the
permitted drainage area.
This Section has been revised as requested.
d. Section IX—Since the property owner is also the applicant, Section IX should not be
filled out. With your permission, I can cross out the original signature on the provided
hard copy, however,you should revise the electronic copy of the form.
In the updated Application, with the registered agent (Anna Spears Tuell) signing,
Section IX was accidentally filled out. Please cross out the original signature in the
hard copy. The electronic copy will be revised.
6. Please correct the following issues with the Deed Restriction Document:
a. The project name listed on this form, "Hadley Hills Townhomes"does not match the
project name as shown on the other submittal documents, "Chatham Habitat for
Humanity Townhouse Development". Please revise as needed. A new original Deed
Restriction Document will be needed if the information on this form is changed.
The project name has been revised to match the other submittal documents.
7. Please correct the following issues with the Supplement-EZ Form:
The Supplement EZ Form has been revised as requested.
8. Please correct the following issues with the O&M Agreement Form:
a. Please specify the type of low-density that is being proposed for this project("Type:"
field on the right side of the"Low Density"line).
The O&M Agreement Form has been revised.
b. Please click on the"CLICK TO UPDATE MANUAL"link on the cover page. This
form uses Macros to generate the correct pages(listing the O&M procedures that are
being agreed to be performed) of this form based on the information entered on the
cover page. A complete O&M Agreement Form will have at least one page per SCM
indicated on the cover page plus the cover page itself.
The O&M Agreement Form has been revised.
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9. Please note that, since the dry detention pond is not a State required stormwater
management component, it was not reviewed for compliance with the MDC.
It is understood that the dry detention pond is not a State required SCM. The dry
detention pond is a requirement based on Siler City's Stormwater ordinances, and
the design will be reviewed by the City's designated engineer.