SW6230104_Response To Comments_20230718

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MCCLURE
1700 Swift Street,Suite 100
North Kansas City,MO 64116
P 816.756.0444
www.mcclurevision.com
July 18, 2023
0
Jim Farkas
W
512 N. Salisbury Street, Office 640E
O Raleigh, NC 27604
• Re: SW6230104 Dunn, NC Petco review comments — Request for Additional Information
Dear Mr. Farkas:
N
! The purpose of this letter is to respond to the Request for Additional Information as provided on July 13, 2023.
Our comment responses are as follows:
The following information is needed to continue the stormwater review:
0 1. Prior Comment 1.a. —"The BUA value (48,213 sf), project area (73,050 sf), and percent BUA (61%)
h do not correspond with the other submittal items." The Supplement-EZ Form indicates that the total
BUA for the entire project (Drainage Area Page, Entire Site Column, Line 8) is 46,265 sf and the total
project area (Drainage Area Page, Entire Site Column, Line 5) is 63,957 sf. These values are different
o than those shown in the stormwater narrative and other submittal items (48,265 sf& 73,050 sf
respectively). NOTE: 48,265 sf/ 73,050 sf = 66.1% BUA whereas 63.3% is shown. Please revise as
needed.
o RESPONSE: The Supplemental EZ form, Narrative, and other submittal items have been revised per this
N comment.
2. Prior Comment 1.b. —"The minimum required treatment volume of the SCM should be based on the
actual drainage area to the SCM, not the project area." Revised calculations showing the minimum
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required treatment value of 1,987 (per the response to comments letter) were not provided. Please
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revise as needed.
o RESPONSE: Revised calculations have been provided and associated plan sheets and submittal forms
have been revised and included in this submittal.
3. Prior Comment 2.b. —"Per the provided USGS topographic map, there appears to be an intermittent
stream running through the property... Relief from this requirement may be allowed when surface
waters are not present in accordance with 15A NCACO2B .0714(3)(a)." We use the USGS topographic
map to determine if there are surface waters present on-site. We understand that these maps may not
o accurately reflect existing site conditions for all sites which is why relief from the surface water
requirements can be allowed when surface waters are not present in accordance with 15A
= NCACO2B .0714(3)(a).When a landowner or other affected party believes that the maps listed in Sub-
Item (3)(a) of this Rule have inaccurately depicted surface waters or the specific origination point of a
stream, or the specific origination point of a stream is in question or unclear, he or she shall request the
Authority to make an on-site determination. On-site determinations shall be made by Authority staff that
are certified pursuant to G.S. 143-214.25A. Registered Foresters under Chapter 89B of the General
Statutes who are employees of the North Carolina Forest Service of the Department of Agriculture and
Consumer Services can make on-site determinations for forest harvesting operations and practices. On-

site determinations shall expire five years from the date of the determination. Any disputes over on-site
determinations shall be referred to the Director in writing within 60 calendar days of written notification
from the Authority. The Director's determination is subject to review as provided in G.S. 150B.Barring
this on-site determination, it is assumed that this surface water is present and must be accounted for.
Please either contact staff from the Fayetteville Regional Office to make a determination with regard to
this surface water or account for this surface water by showing this surface water on the plans, excluding
the surface area from the project area, and including the required vegetated setback.
RESPONSE: We will be contacting staff in Raleigh for a determination as there is not any surface water
present on this site.
4. Prior Comment 3.a. —"General MDC 4 — Please provide calculations showing that the inlets and outlet
of the SCM are stable in accordance with this MDC." These calculations were not provided in the latest
submission. Please provide these calculations.
RESPONSE: Per the erosion control detail sheets,we are implementing a Faircloth Skimmer to be
utilized until vegetation is established. The 10 year velocity of the outflow from our pipe is only 1.47 cfs.
We have provided an oversized riprap pad to dissipate any flow coming from our site. Please note that
our outlet is in a deep existing ditch, so the riprap may not even be needed as there will be larger flows
in the ditch we will be contributing to; our flow to the ditch will be insignificant.
5. Prior Comment 3.d. —"Bioretention MDC 2 — Per the provided state-storage table, the design volume
(shown as 3,674 cf in the Supplement-EZ Form) is not able to be provided within 12" of the planting
surface. Per the detail of the outlet structure, the throat elevation is shown to be at elevation 1 71 .0'
which is in excess of 12" above the planting surface. Please revise as needed. The entire minimum
required treatment volume must be able to be provided above the planting surface and below the
bypass invert. Please revise as needed." Please provide the calculations showing that the minimum
required treatment volume was recalculated as 1,987 cf.
RESPONSE: Calculations have been provided (NRCS method) showing the treatment volume as 3,346
cf. We have raised the pond surface to provide this surface area. We are allowed to attenuate the
larger storm events—thus the higher elevation of the outlet in the structure.
6. Prior Comment 4.a. —"Section IV, 7 —The stormwater narrative indicates that the project area is
73,050 sf = 1.68 ac which is different than the shown value (1.67 ac). Please revise as needed."
Please also revise Section IV, 4 of the Application Form for consistency.
RESPONSE: The forms have been revised to match 1.68 acres.
7. Prior Comment 4.c. — "Section IV, 9 —Since only 1 SCM is being proposed for this project, only one
drainage area column should be provided." Please only include one drainage area per SCM. It is noted
that there are two inlet areas to the proposed SCM however there is only one drainage area to the
SCM. The drainage area used in the Application and Supplement-EZ Forms should reflect the total
drainage area to the SCM (whether these areas are entering the SCM through one inlet, the other inlet
or flowing directly into the SCM). Please revise as needed.
RESPONSE: The forms have been revised per this comment.
8. Prior Comment 5.a.i. — "Supplement-EZ Form, Cover Page, Line 7— Please refer to 15A NCAC
02H .101 7(10) for the vegetated setback width requirement." This item is required to be listed on this
form even if there are no surface waters present within the project area. Please include this value on the
form.
RESPONSE: We have provided a vegetated buffer of 5' minimum around the SCM (as part of the
NDEQ erosion review) as noted in the EZ form. All the drainage from this site enters the SCM via
longer vegetated swales as shown on the plans.
9. Prior Comment 5.b.i.1 . — "Supplement-EZ Form, Cover Page, General — If the project area is not being
subdivided, the new BUA should be listed on Line 10 and should be broken down by type on Line 12."
This item was not addressed. BUA listed on Line 9 is BUA that is allocated to individual, subdivided lots.

There are no individual, subdivided lots associated with this project so there should not be any BUA
allocated to individual, subdivided lots. BUA listed on Line 10 is BUA that is not allocated to individual,
subdivided lots (i.e. common area BUA or BUA associated with a single non-subdivided parcel, such as
this project). Please list the total BUA for this project/drainage area on Line 10 instead of Line 9. Please
also break down the BUA of Line 10 by type on Line 12 (this appears to have been done for the
drainage area columns but was not done for the entire site column). Please revise as needed.
RESPONSE: The Supp EZ form has been revised per this comment.
10. Prior Comment 5.b.ii.1. —"Supplement-EZ Form, Entire Site Column —This column should be an
accounting of the entire project area. When asked for a "drainage area"for the entire site, the entire
project area should be used. All BUA located on-site (whether or not it drains to the SCM) should be
included in this column. The project area (Lines 5 & 6) should correspond to the information shown in
Section IV, 7 of the Application..." Per the response to comments, stormwater narrative, and other
submittal items,the total project area is 73,050 sf (63,957 sf is shown on Lines 5 &6 of the Entire Site
Column), the total BUA for the project is 48,265 sf (46,265 sf is shown on Lines 8 & 9 of the Entire Site
Column), and the percent BUA would be calculated as 48,265 sf/ 73,050 sf = 66.1% BUA (63% is
shown. Please revise as needed.
RESPONSE: The Supp EZ form has been revised per this comment.
1 1. Prior Comment 5.b.iii.1. —"Supplement-EZ Form, Drainage Area Columns—Since only 1 SCM is being
proposed for this project, only one drainage area column should be provided and should include the
entire drainage area to the SCM. The information in this column should correspond with the drainage
area column in the table in Section IV, 10 of the Application." See earlier comment with regard to
having one drainage area per SCM. Please revise.
RESPONSE: The Supp EZ form has been revised per this comment.
12. Prior Comment 5.b.iii.2. —"Supplement-EZ Form, Drainage Areas Page, Line 20—This value should
correspond with Line 22 on the Bioretention Page (see later comment)." This value, 5,116 cf, does not
correspond to the value shown on Line 22 on the Bioretention Page, 5,230 cf. Please revise as needed.
RESPONSE: The Supp EZ form has been revised per this comment.
13. Prior Comment 5.c.i. —"Supplement-EZ Form, Bioretention Cell Page, Line 2 — Please provide this item.
The minimum required treatment volume is calculated using either the Simple Method or the Discrete
NRCS Curve Number Method based on the drainage area to the SCM." This value was not provided
on this form. Please ensure that the calculated minimum required treatment volume is provided on this
line of the form and that the volume provided in the SCM is at least greater than this volume.
RESPONSE: The Supp EZ form has been revised per this comment and calculations are provided with
this submittal.
14. Prior Comment 5.c.iv. —"Supplement-EZ Form, Bioretention Cell Page, Line 21 —This refers to the
surface area of the planting surface." Per the provided stage-storage table, the cross-sectional area of
the SCM at elevation 169.5 (the planting surface elevation) is shown as 1,366 sf whereas a value of
1,814 sf is provided on the Supplement-EZ Form. Please revise as needed.
RESPONSE: The Supp EZ form and plans have been revised per this comment.
15. Prior Comment 5.c.v. —"Supplement-EZ Form, Bioretention Cell Page, Line 22 —This volume refers to
the volume that can be stored between the planting surface and the invert of the lowest bypass. This
volume must be as least as large as the minimum required treatment volume."The value provided on
this form, 5,230 cf, is larger than the storage volume provided within the maximum allowable 12" of
ponding above the bottom of the SCM (approximately 1,940 cf per the provided stage-storage table).
The storage volume provided within the maximum allowable 12" of ponding above the bottom of the
SCM (approximately 1,940 cf per the provided stage-storage table) is less than the minimum required
treatment volume (approximately 3,700 cf, based on the combined drainage area information
provided). Please revise as needed.

RESPONSE: The pond has been revised to raise the storage level to meet the treatment volume
requirements. The total allowed attenuation volume is 5,166 cf in this revised configuration.
16. Please correct the following issues with the Application Form, Section IV, 10 (in addition to the
previously mentioned items):
a. Proposed Impervious Area — It appears that the drainage area value (from the Total/On-site
Drainage Area line) was used for this line. This line should be the total BUA located within the
drainage area to the SCM (equal to the "Total" from the lower table).
RESPONSE: The application form has been revised per this comment.
b. Percent Impervious Area — Please recalculate these values. Percent BUA = Total BUA/Total
Drainage Area. For example, for drainage area 2, the %BUA is shown as 90%, however
calculating the %BUA from the Total BUA (14,341 sf) and Total Drainage Area (29,873 sf)
would equal 48%. Please revise as needed.
RESPONSE: The form has been revised per this comment.
1 7. Application, Section VIII — If the engineer for this project is being changed to Andrew Maysent, please
update the engineer contact information in this section of the Application.
RESPONSE: Andrew is the stamping engineer, but my contact information is still valid for this
application.
18. Please correct the following issues with the Supplement-EZ Form (in addition to the previously
mentioned items):
a. Drainage Areas Page, Line 18— Please include the %BUA for the drainage area column. This
value should correspond to the %BUA listed for the drainage area in Section IV, 10 of the
Application.
RESPONSE: The application form has been revised per this comment.
19. While it is still unclear from the submittal materials, please be aware that, in order for a project to meet
Runoff Treatment, the net increase in BUA must be captured and treated in one or more primary SCMs.
If it is not practicable to capture and treat all of the required BUA, the bypassed areas can be permitted
as a low-density area (provided that the bypass area meets the low-density requirements). Occasionally,
there are situations where it is not practicable to capture all of the required BUA in an SCM and it is not
possible to permit the bypass areas as a low-density area, these situations require a variance/waiver in
accordance with 15A NCAC 02H .1003(6).
RESPONSE: The included information and revisions prove that the designed SCM is adequate to treat
the BUA on this project.
Thank you for the initial comments and please advise if any additional information is needed to complete the
review.
Sincerely,
f;.
Brian Kemp
Team Leader