SW1170501_Response To Comments_20221223

BROOKS
E N G $NEE RIN B A 5 5 f1 N I n I V ti
December 23, 2022
NCDEQ DEMLR — Stormwater Program
512 N. Salisbury Street — Office 640E
Raleigh, NC 27604
Attention: Jim Farkas
Environmental Engineer
Planning & Project Management / Civil Engineering
Surveying 1 Environmental Engineering & Services
17 Arlington Street 1 Asheville NC 28801
www.brooksea.com 1 U8-232-4700
Regarding: Acony Bell — Major Modification
SW1170501
Brickyard Rd, Mills River, Henderson County
Mr. Farkas,
We have received your February 17, 2022 comments from the review of the first submittal of the
Stormwater Permit -- Major Modification plans for the Acony Bell project and offer the
following responses:
1. Please upload the electronic files for the submission at the following link
(htt,os.Iledocs.deA.nc.zoy/Fornts/SW-Suynlen:ental-Upload . It appears as though the
entail that we send out when we accept the project as administratively complete and
instructing you to upload the electronic files was never sent out by us.
• Digital documents have been uploaded to the portal.
2. Please correct the following issues with the Application:
• Section IV, 10:
i. Total Drainage Area & On -site Drainage Area — Please use the project
area (50.0 ac) not the property area (50.5 ae) for this item and please
show this item in square feet, not in acres.
U. Proposed Impervious Area — Please show this item in square feet, not in
acres.
• Revised as requested on new Application page 3.
3. Please correct the following issues with the Supplement-EZ Form:
Cover Page:
i. Line 2 —Please use the project area (50.0 ac) not the property area (50.5
ac) for this item.
ii. Line 9 — BUA was proposed within the vegetated setback for Phase I of
this project (The main roadway of Phase I crosses Goldntine Branch).
Please complete this item If the BUA within the vegetated setback does

not meet.15A NCAC 02H.1003(4)(c-d), 15A NCAC 02H.1017(12) can
be used).
• The cover page has been updated as requested. Regarding line 9 being updated
from "NIA" to "Yes" - the BUA within the buffer is limited to a perpendicular
road crossing. Runoff from the crowned road sheet flows through a vegetated
shoulder below the road (loft minimum distance) before contacting surface
waters. Our understanding is this configuration is consistent with the intents of
low -density design/development,
• Drainage Areas Page:
4 Lines 5-6 —Please use the project area (50.0 ac) not the property area
(50.5 ac) for this item and please show this itens in square feet, not in
acres. NOTE: Line 7 should also be shown in acres, but this is a moot
point since it is zero.
• Revised as requested.
4. 15A NCAC 02H.1003(2)(c) requires tlue conveyances used for low -density projects to
be vegetated (with allowable exceptions for erosion protection). Would it be possible to
reconfigure the swales in a manner that reduces the number of swales that have riprap
lining or swap the riprap lining for a grass lining with check dams? For example,
could swale 4A be directed under the existing gravel roadway and toward the
delineated stream (instead of directed into Swale 3A)? If the drainage area to Swale 3A
is reduced, it should be possible to remove the riprap lining for this swale and possibly
Swale 2A. Please also look into tlse possibility of changing the provided Swale cross -
sections to eliminate the riprap lining. The provided swales have a bottom width of 0.5
ft, but widening this bottom width could increase tlse capacity of the Swale and
(hopefully) remove the need for the riprap lining If it is not possible to remove the
riprap lining due to erosion concerns, it is understandable since the topography of this
site is fairly steep (with road slopes regularly being in excess of 10%). NOTE: The
provided Swale calculations are sized for the 25 year design storm, but the State only
requires that the IO year storm be conveyed non-erosively (this may help reduce the
amount of riprap used).
• Due to the topography and grades of the road, the owner would prefer to utilize
the rip -rap ditches as designed and would like to preserve the proposed
configuration of SW-4A to SW-3A as there are some sensitive erosive areas
downgradient of where SW-4A's pipe would discharge, including some
maintenance structures, dirt paths, and a well house. Due to the increased flows
resulting from this configuration, the steep natural topography, and with interest
in conservative design for a changing environment, all swales have been designed
for the 25-year storm and discharged to a location with the best capacity of
dispersed flow over mild slopes and infiltration potential.
5. Would you like this permit to be reissued with the project density written as dwelling
units per acre (Max 2 dwelling units per acre) or as a percentage of the project area
that can be BUA (max 24% BUA)? Both options are allowable for low -density projects
subject to 15A NCAC 02H.1017(4). The dwelling units per acre permit condition is
generally easier to demonstrate compliance with, but the percent BUA permit condition

world make it easier/possible to add additional homes to the property at some point in
the future.
• The preference would be the 24% BUA limit.
6. Please provide the following:
• Ix electronic copy of all of the submittal materials received tip to this point.
• Ix hard copy & Ix electronic copy of the revised page of the Application.
• Ix hard copy & Ix electronic copy of the revised pages of the Supplement EZ
Form (since the signature page is being modified, you will need to provide a
new original signature on the hard copy).
• Ix hard copy (Zx hard copies for plans) & Ix electronic copy of anything related
to changes in the proposed swales (if applicable).
• Revised Application Page and Supplement-EZ Fonn will be mailed to your office
to arrive in January 2023. Electronic document uploads have been provided as
well.
let me know if you have any other questions regarding this matter. Sincerely,
Eric J. Hutchison 111, RE.
Brooks Engineering Associates, PA
15 Arlington St — Asheville, NC 28801
chutchison c,brooksea.com_
Office: 828-232-4700
Cell: 717-503-1188
Enclosures: Revised Application page 3
Revised Supplement EZ Form