SW3200601_00_SpeedwaySubstation_CommentResponse_20201020

October 19, 2020

Jim Farkas
Environmental Engineer
NC Dept. of Environmental Quality
3800 Barrett Drive
Raleigh, NC 27609

RE: Speedway Substation – Stormwater Permit No. SW3200601

Please find attached the Applicant’s resubmittal to NCDEQ Department of Environmental Quality –
Stormwater Section addressing comments issued on 09/23/2020 for the above referenced project. The
resubmittal package includes the following information:
• One (01) Comment Response Letter
• Two (02) Updated 24”x36” Set of Construction Documents
• One (01) Revised copy of Stormwater Management Permit Application
• One (01) Revised copy of Low Density Supplement
• One (01) USACE Approved JD (SAW-2019-02198)
• One (01) Email coordination with Mooresville NCDEQ Office regarding determination

Please contact me at [phone] or [e-mail] should you or your staff have
any questions concerning our resubmittal.
Sincerely,

Jennifer Lester
Project Manager

Speedway Substation
NCDEQ Comment Responses
1.Original Comment 2, Surface Water Areas – The way we define it, surface waters are present on-
site if they appear as a blue line stream on the USGS topographic map (Which appears to be the
case with the ephemeral stream). If you believe that the USGS topographic map is incorrect and
that there are no surface waters located on-site, you can appeal per 15A NCAC 02B .0233(3)(a)
via 15A NCAN 02H .1017(10) –
“EXEMPTION WHEN AN ON-SITE DETERMINATION SHOWS THAT SURFACE WATERS
ARE NOT PRESENT. When a landowner or other affected party believes that the maps
have inaccurately depicted surface waters, he or she shall consult the Division or the
appropriate delegated local authority. Upon request, the Division or delegated local
authority shall make on-site determinations. Any disputes over on-site determinations
shall be referred to the Director in writing. A determination of the Director as to the
accuracy or application of the maps is subject to review as provided in Articles 3 and 4 of
G.S. 150B. Surface waters that appear on the maps shall not be subject to this Rule if an
on-site determination shows that they fall into one of the following categories.
i.Ditches and manmade conveyances other than modified natural streams un
less constructed for navigation or boat access.
ii.Manmade ponds and lakes that are located outside natural drainage ways.
iii.Ephemeral (stormwater) streams.”
The important takeaway from this is that the on-site determination must be made by our
Division, not an outside consultant. To set up this on-site determination, you should reach out to
the Mooresville Regional Office and they will be able to assist you.
Alternatively, you can account for the ephemeral stream as a surface water and it shouldn’t
negatively impact the project or require any redesigning. There are two items that on-site
surface waters impact, the project area/percent BUA calculations and the required vegetated
buffer. With regard to the project area/percent BUA calculations, the impact of including the on-
site surface waters should be negligible since the surface water area is relatively small compared
to the rest of the site and the proposed %BUA is well below the maximum allowable (24%). With
regard to the vegetated buffer, the rules require a 30 foot horizontal buffer landward of all
surface waters. This buffer is essentially a BUA exclusion zone and it does not appear that any
proposed BUA is located closer than 30 feet to the surface waters so this should also be
negligible.
Please either:
1)Contact the Mooresville Regional Office to set up an on-site surface water
determination. Please provide me the results of the determination once it has been
complete. If the results indicate on-site surface waters, please see “2)”, otherwise
no further action is required to address this item.
Redo the project area and percent impervious area calculations (Section IV, 6-8 & Low Density
Supplement) and include a vegetated buffer around the surface waters on the plans.
Response: Per coordination with the Mooresville DEQ office, they concur with the USACE
determination of the Ephemeral stream. Please see attached email coordination with the
Mooresville DEQ office. The approved USACE JD has also been included with this submittal for
reference.
2.Original Comment 5, Proposed BUA Designation – The table in Section IV, 10 of the Application
is filled out correctly save for the designation of the proposed BUA type. Generally, “Future”
BUA is reserved for projects that are multi-phase or for projects with a planned future expansion
(in addition to the main BUA being permitted). A more appropriate proposed BUA designation
would probably be “On-site Road” and/or “On-site Parking” and/or “On-site Other” (As to be
consistent with the information entered in the Low-Density Supplement, broken down by
drainage area).
Please correct the table in Section IV, 10 of the Application.
Response: The table in Section IV, 10 of the Application has been updated accordingly; see
updated copy of application attached.
3.Original Comment 6, Low Density Supplement, Uniform Lot Size Calculation – The “DF” value
used in this equation is the actual, proposed percent impervious area of the site (Section IV, 8,
expressed as a decimal), not the allowable maximum (24%). This form was designed to be used
for subdivisions where there is BUA allocated to individual lots and BUA allocated to common
areas (This form isn’t really designed for this application, but as I stated in my comment letter, I
will allow you to use it if you wish).
There are 2 ways that you can represent this site on the form:
1)You can assume that the entire project area is 1 individual lot and there is no
common area. The equation would look like this: (SA * DF) – (RA: 0) – (OA: 0) = BUA
per Lot = 64,902 sf
2)You can assume that there are no individual lots and the entire site is common area.
The equation would look like this: (SA * DF) – (RA: 35,277) – (OA: 29,625) = BUA per
Lot = 0 sf
NOTE: The project area (SA) and percent BUA (DF) may change depending on how Original
Comment 2 is addressed so they were left as variables in the above equations. They should be
filled in with the appropriate values in the resubmission.
Please correct the first and second pages of the Low Density Supplement.
Response:The first and second pages of the Low Density Supplement have been updated per
the option 2 listed in the comment above; it is assumed that there are no individual lots and the
entire site is common area. Please see updated copy of Low Density Supplement attached.