SW5240801_Response To Comments_20241119

S I )
5710 Oleander Drive
Suite 110
November 8, 2024 Wilmington, NC 28403
[phone]
Jacob Beeker wsp.com
Stormwater Permitting Engineer
DEMLR Post-Construction Stormwater Program -Raleigh Regional Office
512 N.Salisbury St.Office 625Z, Raleigh, NC 27604
Re: Request for Additional Information
Stormwater Permit No.SW5240801
Spring Hope 115kV Substation Rebuild
Nash County
Mr. Beeker,
In response to the comments received (November 05, 2024), regarding the application and submittal packages for the above
referenced project,we off the following responses in italicized text.
1. Please ensure that all project documentation is uploaded to the digital repository,as required by 15A NCAC 02H
.1042(2).The current O&M Agreement could not be found within the repository.
Response: Understood.All project documentation will be uploaded to the digital repository.
2. Since this project is within the Tar-Pamlico river basin, it is subject to the Tar-Pamlico Nutrient Strategy Rules,
outlined in 15A NCAC 02B .0731.To demonstrate compliance with these rules, please revise the project package as
follows:
a. Please provide calculations demonstrating compliance with the nitrogen and phosphorous loading rate
targets outlined in 15A NCAC 02B.0731(e)(1), using the most current version of the SNAP Tool,found
under the Stormwater Nutrient Accounting Tools heading at
htt os://www.deq.nc.gov/about/divisions/water-resources/water-planning/nonpoint-source-
planning/nutrient-practices-and-crediting#StormwaterNutrientAccountingTools-2786
Response: Calculations using the most current version of the SNAP Tool are provided with this resubmittal.
b. Please provide the necessary riparian buffers as outlined in 15A NCAC 02B.0259(4). Please also ensure
these buffers are shown on the main set of plans,as well as indicated on the Supplement-EZ form.
Response: Zone 1 (30'undisturbed vegetation)and Zone 2(20'managed vegetation)buffers have been added to
the plans and indicated on the Supplement-EZ form.
3. Project documentation refers to the area within the fenced yard at this substation as being excluded from the
definition of Built-Upon Area using the criteria of"landscaping material, including, but not limited to,gravel,
mulch,sand,and vegetation, placed on areas that receive pedestrian or bicycle traffic or on portions of driveways
and parking areas that will not be compacted by the weight of a vehicle,such as the area between sections of
pavement that support the weight of a vehicle."The area indicated as being excluded from BUA accounting must
be maintained in some form of landscaping material in order to be eligible for exemption under the above criteria.
If this area will be paved over with concrete, it cannot be excluded from BUA accounting.
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WSP Project No. 7818-23-0203 Page 1

Please indicate on the main set of plans the landscape material that will be used for the fenced-in portion of the
substation (if this information has been missed, please direct the reviewer to this information)so that eligibility for
the exemption may be verified,or account for this area as BUA throughout the project package.
Response: For clarification,project documentation refers to the following sentences taken from A-4 Built Upon
Area, "Any size stone or aggregate used on portions of projects that receive infrequent vehicular traffic
(approximately twice a month or less)may be counted as pervious regardless of the depth of the stone
layer. This includes applications such as decorative landscaping, drainage swales, weed control, and the
area within the fenced yard at electrical substations."Please see callout"REFRESH SUBSTATION YARD
WITH 3"#57 CLEANED WASHED GRANITE STONE(BY OTHERS)"on Sheet 9 as well as associated details
1, 2, 3, and 4 on Sheet 12 of the plans that indicates the material being used within the substation
fencing.
4. Consistency
Please revise the following for consistency:
a. The Application shows that 8,977 sf of Other on-site BUA will be proposed,while the Supplement-EZ form
shows that 13,922 sf of Other on-site BUA will be proposed. Please report the amount of proposed new
BUA on these lines,as Existing BUA is accounted for in other locations.
NOTE: Measurement of the proposed BUA from the provided plan sheets does not appear to reflect the 8,977
sf amount.
Response: Application and Supplement updated to reflect the proposed new BUA of 8,977 sf. Breakdown of
proposed BUA is as follows:
• Substation Shoulder(outside of substation fence)—3,987 sf
• Access road—4,990 sf
5. Application
2x hard copies of the Application with the following corrections made, as required by 15A NCAC 02H.1042(2)(a)
and Section VI, 1 of the Application:
a. Section IV, 6—There appears to be surface waters within the project area. Please account for said surface
waters here.
Response:The surface waters(although not identified on the DWR Surface Water Classifications Map) within
the project parcel boundary have accounted for in this resubmittal.
b. Section IV, 7—Please revise to account for the on-site surface waters by subtracting their surface area
from the project area.
Response:Section IV, 7 has been revised to account for the on-site surface waters.
c. Section IV, 10—Please make the necessary revisions for consistency outlined above.
Response:Section IV, 10 has been revised.
d. Section VIII—Please revise to indicate the new engineer who will be the point of contact for this project
moving forward.
Response: Section VIII has been revised with the new engineer and point of contract, Michael Brock, PE.
6. Supplement-EZ
1x hard copy of the complete, original Supplement-EZ Form with the following corrections made, as required per
Sections V& VI,3 of the Application:
a. Cover Page
i. Line 7—Please revise this line to reflect the revisions required to meet the Tar-Pamlico riparian
buffer rules(Comment 2b).
Response: Line 7 has been revised.
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WSP Project No. 7818-23-0203 Page 2

b. Drainage Areas Page
i. Line 10—Please complete this line.
Response: Line 10 has been completed.
ii. Line 15—Please complete this line to reflect the amount of existing BUA that will remain.This
should reflect what is shown on the Application under"Existing BUA*** (sf)."
Response: Line has been revised.
iii. Line 22—See Comment 3 regarding the BUA exemption.See Comment A under the Consistency
section regarding the amount of BUA proposed.
Response: See response to Comment 3.
c. Low Density Page
i. Line 5—Once the Swale Table is completed, please revise this section to indicate the highest
value from the Vactuai column.
ii. Please complete the Swale Table.The information entered here should correspond to the
permanent conditions of the proposed swales, as well as the conveyance of the ten-year storm
(15A NCAC 02H .1003(2)(c)(ii)).This information should match what is shown in the provided
calculations.
Response: Please see revised Low Density Page and proposed swale calculations, which have been
updated to reflect the final vegetated condition of each swale.
7. Plans
2x hard copies of revised plan sheets with the following corrections made,as required by 15A NCAC 02H.1042(2)(g)
and Section VI,8 of the Application:
a. Please show the required riparian buffers on the main set of plans,as required by Section VI, 8p of the
Application.
Response: Zone 1 (30'undisturbed vegetation)and Zone 2(20'managed vegetation)buffers have been added to
the plans.
b. If the fenced-in area of this substation is to be considered as not BUA, please indicate the type of landscape
material that will be used on the main set of plans. If this information has been missed, please direct the
reviewer to said information.
Response: See response to Comment 3.
8. O&M Agreement
1x original,signed&notarized hard copy of the O&M Agreement Form, as required by 15A NCAC 02H.1042(2)(j)
and Sections V& VI, 3 of the Application:
a. Please submit a revised O&M Agreement indicating that permanent swales are proposed as a portion of
this project.When a Low Density Area is selected, use the drop-down menu to the right to select the
appropriate option.
Response: Revised O&M Agreement included with this resubmittal.
9. Calculations
1x signed,sealed, and dated hard copy of calculations with the following corrections made, as required by Section
VI, 7 of the Application:
a. Please include the calculations required to demonstrate compliance with the Tar-Pamlico Nutrient
Strategy rules(See Comment 2a).
Response: Calculations using the most current version of the SNAP Tool are provided with this resubmittal.
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b. The provided calculations must correspond to the permanent conditions of the swales in question.
Temporary linings,such as the Excelsior lining shown in the calculations, are considered an erosion
control measure and are not indicative of the final vegetated state of the swales. Please revise as
necessary.
Response: Calculations have been included with this resubmittal for the final vegetated state of the swales.
Also,plans have been revised to show final vegetated state.
c. Please include information regarding how the ten-year storm intensity used in the swale calculations was
determined,so that the swale calculations may be verified.
Response: The intensity(5.48 in/hr)used in the swale calculations was taken from NOAA Atlas 14, Volume 2,
Version 3, Point Precipitation Frequency Estimates for Spring Hope, North Carolina. This intensity
correlates to a time of concentration of 10 minutes.
10. Please provide a Response to Comments letter indicating, in a point-by-point manner, how each of the above
comments has been addressed.This item is required per 15A NCAC 02H .1042(3)(b).
Response: This document to serve as comment response letter.
11. Provide PDFs of all revisions,2 hardcopies of revised plan sheets, 1 hardcopy of other documents,and a response
to comments letter briefly describing how the comments have been addressed.
Response: Noted.
Thank you again for your assistance in review of this project. If you have any questions, please do not hesitate to contact me by
email [e-mail].
Sincerely,
Michael Brock, PE
Senior Civil Engineer
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