20221576 Ver 1_01_Project Blue HE-0006 - USACE RFI 3 - Response to Comments (Narrative Only)_20230804

Kimley>»Horn
August 4, 2023
Mr. Dave Bailey
US Army Corps of Engineers
Raleigh Regulatory Field Office
3331 Heritage Trade Drive, Suite 105
Wake Forest, NC 27587
Ms. Sue Homewood
401 and Buffer Permitting Branch
1617 Mail Service Center
Raleigh, NC 27699-1617
RE: Action ID: SAW-2014-00610
Response to USACE Comments
VinFast Manufacturing Facility — Project Blue
Moncure, Chatham County, North Carolina
Dear Mr. Bailey and Ms. Homewood,
On behalf of our client, VinFast Manufacturing US, LLC, and in conjunction with NCDOT and their
consultant RK&K, Kimley-Horn is submitting the attached (additional) information for the above
referenced Project per the US Army Corps of Engineers (USACE) email dated July 26, 2023. The
USACE email provided comments and requested multiple pieces of additional information and
clarification.
Below is an outline of the USACE comments (red italic font) along with a brief narrative addressing
each comment from the Project team.
USACE Comments (received July 26, 2023)
Proiect Blue
1. Add the Corps approved delineation to Alternative 4 overall plan to enable full evaluation of
potential indirect impacts related to grading/drainage on the site. Please also show grading
limits, stormwater controls and other proposed infrastructure that would ensure that existing
aquatic resources maintain their hydroperiod;
The USACE-approved delineation has been added to the Alternative 4 overall plan, along with
more detailed site features, grading limits, stormwater controls, and other proposed hydrologic
infrastructure as currently designed. Note that due to the long-term nature of this project,
Phases 2 and 3 are not fully designed and are shown as conceptual layouts in this application.
The proposed stream crossings in Phase 3 have undergone more detailed designed to facilitate
the USACE and NCDWR review. All stormwater infrastructure and detailed grading limits for
Phases 2 and 3 will be designed in compliance with applicable USACE and NCDWR
requirements, and those features will be fully located within the areas shown on the conceptual

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layouts with no additional impacts to Waters of the US anticipated. However, as the Project
advances, the Project Blue team will coordinate with the USACE and NCDWR should any new
impacts be necessary and unavoidable and will discuss the justification and potential need for
a permit modification if required at that time. The updated Alternative 4 overall plan is attached.
2. The conceptual Phase 3 plan building layout does not appear to match the detail plan for
Crossings 4 and 5. Direct impacts appear likely to Wetland W113, and indirect impacts appear
likely to the remainder of Wetland W112 and Stream 123 based on conceptual Phase 3 plan
where a building appears to cut off or re-route hydrology away from this drainage.
The overall site plan for Alternative 4 and conceptual Phase 3 building layout has been revised
to avoid impacting wetland W113 and indirectly impacting wetland W112 and stream S123.
The detail plan for crossings 4 and 5 has been updated to match as well. As described above,
stormwater management has not been fully designed for Phase 3, however as the Project
progresses, the detail design for Phase 3 will ensure aquatic resources maintain their
hydrologic input from their localized drainage area and are not indirectly impacted as a result
of this Project. The updated Alternative 4 overall site plan and detail plan for crossings 4 and 5
are attached.
3. Impact Site 4: given the small remnant of wetland proposed to remain downstream of the rip
rap pad, the Corps would consider this wetland remnant as additional permanent wetland loss
for this crossing.
The Project Blue Permit Impact Drawing - Impact Site 4 has been updated to reflect the
remnant wetland as additional permanent wetland loss for the crossing. The updated permit
drawing for Impact Site 4 has been attached to this package.
4. Thank you for the Archeological Survey Report you provided for Phases 1B, 2, and 3 f Project
Blue. Given that the proposed project activities occur in areas that contain archeological
resources, consultation may need to be initiated with the State Historic Preservation Office.
The Corps is currently reviewing this project in this context to determine any responsibilities
pertaining to Section 106 of the National Historic Preservation Act (NHPA). If required, please
note that NCSHPO may require up to 30 days to respond to our coordination request. Please
note that Corps authorizations cannot preclude completion of Section 106 of the NHPA.
The Project Blue team notes the possibility of required consultation with the NCSHPO if
deemed necessary by the USACE and understands that authorization from the USACE cannot
prevent the completion of Section 106 of the NHPA.
HE-0006
1. In the response to the Corps request for additional information, received by our office via email
on 311012023, a map was provided entitled "STIP HE-0006" "Figure 5B: Prior Concepts Map"
and Tables 1 and 2 were provided showing the alternative routes evaluated for HE-0006.
Please update and provide those items to include the expanded study area referenced and
shown in the NCDOT supplemental PJD request package submitted to our office on 412712023.
The prior submittal of Figure 5B, Table 1, and Table 2 included the most recent fieldwork and
mapping that were reflected in the PJD request package submittal on 4/27/23. The fieldwork
delineating the expanded study area was completed prior to development of Figure 5B, Table
1, and Table 2. While draft information was utilized at that time, no changes to the delineated

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features were required and the resources utilize the same mapping provided in the 4/27/23
submittal. Therefore, no changes to Tables 1 or 2 are required. However, the Figure 513 series
was focused on the concept corridors so the fieldwork mapping was clipped at the boundaries
of the corridors for the illustration. Those figures have been updated for this response so that
the delineated mapping is not clipped at the corridors.
2. Phase 1 B Plans:
a. Site 1: the "triangle" of temporary wetland impacts bound by the permanent
mechanized clearing and fill wetland impacts should also be considered permanent,
as this small remnant wetland area would not retain existing wetland function following
construction;
The referenced triangle has been revised from temporary to permanent impacts.
b. Site 2:
i. Please provide a cross-section view of the inlet and outlet of the proposed
double box culvert that clearly shows if both boxes would be the low flow
structure, or whether one would be set or silled higher than the other to create
a low- and high -flow box. Please also provide a detail of the proposed
floodplain bench, including how these areas would be stabilized and
revegetated following construction.
Inlet and outlet details for the box culvert are provided with the ditch details on
Sheet 2D-2.
ii. Wetland WM appears to be wide enough such that at -grade floodplain culverts
are warranted to maintain hydrologic flow across the larger wetland area.
Two 36" equalizer pipes have been added under L1 BC to connect wetland WM
on Sheet 5.
c. Site 4: project plans reference "Existing Channel w/6' Bench See Detail AF." Please
provide this detail for review.
Detail AF is provided with the ditch details on Sheet 2D-2.
d. Site 5: Wetland WJ would be segmented into smaller sections as currently proposed,
including what would become a disjunct area within a gore area surrounded by an
access ramp. How would this wetland area maintain its current function as proposed?
Unless otherwise justified, this wetland portion appears to be an indirect impact of the
proposed project, suitable for compensatory mitigation at a 1:1 ratio.
The drainage area for wetland WJ is being matched from existing to proposed
conditions through the proposed 54" RCP and 48" CAP. The remaining wetland within
the gore area is larger than a quarter acre and is maintaining wetland functions.
e. Sites 7 and 9: the plans appear to show rip rap on either side of the banks of Streams
SBD and SBB. Please ensure that, if rip rap is proposed to be placed below the
Ordinary High Water Mark (OHWM) of the channel, that the impacts are listed as
Permanent with no net loss of stream function.

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These impacts at Sites 7 and 9 have been changed to permanent stream impacts.
3. Phase 1D Plans: The project plans at Site 1 appear to cut off the western extent of proposed
wetland impacts (Wetland WAT).
The plans have been revised to show the extent of the Site 1 impacts.
Phase 2A and 2B Plans: note that the conceptual plans submitted appear to indicate future
opportunities to avoid and minimize impacts to aquatic resources. The stage of design
presented does not show drainage structures or other details necessary to fully evaluate such
measures and therefore comments herein are withheld. Several wetland areas may be
considered complete functional losses due to small remaining remnants, rerouting hydrologic
input, etc., including Wetlands WBE (Site 2) and WBF (Site 3) in Phase 2A, and Wetlands WBJ
and WCE (Site 1), WAK (Site 2), WZ (Site 8), WAB (Site 9), and WAC (Site 15) in Phase 2B.
Phase 2 permit impacts will be re-evaluated once drainage and erosion control design has
been completed.
City of Sanford Utilities
Responses to the request for additional information regarding City of Sanford Utilities is attached to this
package on Freese & Nichols letterhead for easier review and overall clarity.
If you need any additional information to assist in your review of this RFI Response Package, feel free
to contact me at 919-678-4155 or [e-mail].
Sincerely,
Kimley-Horn and Associates, Inc.
Jason Hartshorn, PWS
cc: Ms. Thi Van Anh Nguyen; VinFast Manufacturing US, LLC
Mr. Monte Matthews, USACE
Mr. Shelton Sullivan, NCDWR
Ms. Sue Homewood, NCDWR
Mr. Colin Mellor, NCDOT
Mr. Jeffrey Teague, NCDOT Division 8