20171559 Ver 3_SMP More Info Requested_20220525

DocuSign Envelope ID: 9507C5B3-3334-46E5-91A1-732E392F87AD
ROY COOPER
Governor
ELIZABETH S. BISER
Secretary
RICHARD E. ROGERS, JR.
Director
Greensboro Randolph Megasite Foundation
Attn: Mr. Jim Melvin
324 W. Wendover Ave, Suite 207
Greensboro NC 27408
Delivered via email to: [e-mail]
NORTH CAROLINA
Environmental Quality
May 25, 2022
DWR # 20171559 v3
Randolph/Guilford County
Subject: REQUEST FOR ADDITIONAL INFORMATION ON STORMWATER MANAGEMENT PLAN
Greensboro Randolph Megasite —Toyota Battery Manufacturing
Dear Mr. Melvin:
On April 29, 2022, the Division of Water Resources (Division) received your Stormwater Management
Plan (SMP) pursuant to Condition 5 of 401 Individual Water Quality Certification #WQC004625 issued
February 1, 2022 for the subject project. The Division has reviewed the SMP and the following
additional information is necessary to continue the review:
General Comments:
1. Based on the significant deviations from the previously reviewed conceptual stormwater
management plan, the Division has concerns that the proposed stormwater management of the site
may result in secondary impacts to downstream waters. These concerns were expressed to you
previously in requests for additional information sent on September 3, 2021 and November 5, 2021.
Originally, the entire watershed draining to stream S45 was proposed to be redirected to Wet Pond
A3 which had been designed such that the outlet of the pond would provide a discharge of
hydrology back into the majority of the stream channel. Now, Wet Pond A3 has been removed from
the proposed SMP. The Division's previous concerns about indirect impacts to downstream waters
causing a significant reduction in stream function from a reduction in hydrology require a re-
evaluation.
The SMP submitted on April 29, 2022 states that the underdrain system that is proposed to be
installed in Stream S45 will connect the groundwater to the remaining channel below the project
pad. While the Division does not dispute that groundwater will be connected to the downstream
channel, groundwater connectivity is unlikely to be sufficient to provide the same level of function
of the downstream channel. As previously stated by the project consultants, the stream channels
within the property site are weakly connected to groundwater. Surface runoff within the watershed,
and shallow interflow provide a significant source of hydrology to the stream channels within the
project site. The SMP submittal indicates that 40 acres of the drainage area to S45 will not be
NORTH ntntF NA
o.p.rereM m Environmental o..nry
North Carolina Department of Environmental Quality I Division of Water Resources
512 North Salisbury Street 11611 Mail Service Center I Raleigh, North Carolina 27699-1611
919.707.9000

DocuSign Envelope ID: 9507C5B3-3334-46E5-91A1-732E392F87AD
Greensboro Randolph Megasite Foundation
DWR# 20171559 v3
SMP review - Request for Additional Information
Page 2 of 3
impacted by the project. Please clearly show this drainage area on a plan sheet/map, as the Division
is unable to verify this information using available mapping technology. In addition, using the most
downstream impact location to estimate S45's drainage area, more than 200 acres drain to S45.
Therefore the 40 acres assumed to still be draining to the lower portion of S45 only constitutes a
small percentage of the stream's entire the drainage area. The Division requires one of the
following items to resolve this issue:
a. Provide scientific evidence, data, modeling or literature that supports the position that the
lower portion of Stream S45 will continue to support the current level of stream function.
b. Submit a 401 modification application to incorporate indirect impacts for the remainder of
Stream S45.
c. Submit a stream monitoring plan for S45 which includes baseline evaluation, functional
monitoring for a minimum of 3 years after the surface flow has been completely redirected to
stormwater measures in other drainage areas, a functional assessment protocol for determining
indirect impacts at the end of the monitoring period, and a contingency plan if the monitoring
shows that indirect impacts have occurred to stream S45.
2. Engineering Plans: Please provide profiles and detailed drawings of the following items:
a. The proposed stormwater wet ponds (East and West)
b. The proposed spill basins (East and West)
c. Swales and stormwater drainage system (routing from Built Upon Area (BUA) to conveyances
and/or stormwater control measures (SCMs))
d. The proposed diversion structures
e. The proposed preformed scour basins
SMP Engineering Review Comments:
3. The wet pond's inlet (forebay) and outlet locations seem to be close to each other, especially the
East pond. The MDC#4 for wet pond requires inlet and outlet to be located in a manner that avoids
short circuiting. Will baffles be installed in the wet ponds to lengthen the stormwater flow path as
much as possible or are there other strategies being used to avoid short circuiting?
4. Please provide the Operation and Maintenance Plan for the proposed spill basins, wet ponds, and
preformed scour basins.
5. Please provide a signed and notarized O&M Agreements for the proposed SCMs.
6. Please submit a signed and sealed cover page of the Supplemental EZ form. Please also note that
the submitted Supplemental EZ form indicates there are 4 drainage areas, however, only 2 drainage
areas are identified and used throughout the report. In addition, please provide answers for
questions 52-54 on the form.
NORTH raaoJNa
Department at Environmental Puolity
North Carolina Department of Environmental Quality I Division of Water Resources
512 North Salisbury Street 11611 Mail Service Center I Raleigh, North Carolina 27699-1611
919.707.9000

DocuSign Envelope ID: 9507C5B3-3334-46E5-91A1-732E392F87AD
Greensboro Randolph Megasite Foundation
DWR# 20171559 v3
SMP review - Request for Additional Information
Page 3 of 3
7. The numbers for total drainage areas and proposed BUAs on the application (SWU-101) and
Supplemental EZ forms are inconsistent. Please update.
8. Please provide a summary of your consulting results with Dam Safety (DEMLR) regarding the
proposed spill basin structures and wet ponds.
Pursuant to Title 15A NCAC 02H .0502(e), the applicant shall furnish all of the above requested
information for the proper consideration of the application. Please respond in writing within 30
calendar days of receipt of this letter by submitting all of the above requested information through
this link: https://edocs.deq.nc.gov/Forms/Supplemental-Information-Form (note the DWR#
requested on the link is referenced above).
If all of the requested information is not received within 30 calendar days of receipt of this letter, the
Division will be required to re-evaluate the 401 Water Quality Certification as issued.
Please contact Sue Homewood at 336-776-9693 or [e-mail] if you have any
questions or concerns.
Sincerely,
r—DocuSigned by:
Pc 44 G 1O020 .
"-949D91BA53EF4E0...
Paul Wojoski, Supervisor
401 & Buffer Permitting Branch
Electronic cc: Andrew Williams, USACE Raleigh Regulatory Field Office
Wendee Smith, S2 Consulting
Vickie Miller, HDR
Curtis Martin, Jr., Toyota
NCDWR 401 & Buffer Permitting Branch Electronic file
D_E
NORTH CAROJMQ
Department at Environmental Puolity
Filename: 20171559 Ver3_GRMS_SMP Addinfo_Guilford-Randolph.docx
North Carolina Department of Environmental Quality I Division of Water Resources
512 North Salisbury Street 11611 Mail Service Center I Raleigh, North Carolina 27699-1611
919.707.9000