24054_AJACC Auto_VIMS Mod Request Rev1 and Review Letter_20220818

August 19, 2022

Sent via Email

Trinh DeSa, PE Hart & Hickman, PC 2923 South Tryon Street, Suite 100 Charlotte, NC 28203
[e-mail]
Subject: Vapor Intrusion Mitigation Plan – Modification Request Rev. 1 AJACC Auto 304 Yeoman Road Charlotte, Mecklenburg County Brownfields Project Number 24054-20-060 Dear Mr. DeSa:
The North Carolina Department of Environmental Quality Brownfields Program (DEQ Brownfields) received and reviewed the Vapor Intrusion Mitigation Plan (VIMP) Modification Request Revision 1 dated August 18, 2022, for the above referenced Brownfields Property.
DEQ Brownfields has found the requested modification to satisfy elements of the Land Use
Restrictions of the pending Brownfields Agreement for design of a vapor mitigation system, and as such, this letter constitutes DEQ approval of the modification request.
As will be expressed in the Brownfields Agreement for this project, an essential component of public health protection for this design is the professional engineer’s seal of these
documents that the proposed design will be effective at mitigating the potential for vapor
intrusion at the property and protecting public health. In addition, DEQ Brownfields reserves the authority to require confirmation of efficacy in the future.
Be advised that this review from the Brownfields Program does not waive any applicable requirement to obtain any necessary permits, licenses or certifications for the above listed
activities nor does it waive any requirement to comply with applicable law for such activities.
Trinh DeSa, PE August 19, 2022 Page 2

If you have questions about this correspondence or require additional information, please
contact me by phone at [phone], or e-mail at [e-mail].
Sincerely,
Peter L. Doorn Brownfields Project Manager

ec: Josh Glover, Greystar Development East, LLC Chris Hustek, Greystar Development East, LLC Michael Innominato, Greystar Development East, LLC Warees Smith, KTGY
Andrew Besu, Hart & Hickman
David Kahn, Hart & Hickman Tracy Wahl, DEQ Kelly Johnson, DEQ Kevin Slaughter, DEQ

Via Email

August 18, 2022

NCDEQ – Division of Waste Management
Brownfields Program
1646 Mail Service Center
Raleigh, NC 27699-1646

Attn: Mr. Peter Doorn

Re: VIMS Modifications Approval Request – Revision 1
Vapor Barrier Wall Modification
AJACC Auto Brownfields Site
301 Verbena Street
Charlotte, Mecklenburg County, North Carolina
Brownfields Project No. 24054-20-060
H&H Project No. GSL-004

Dear Pete:

On behalf of Greystar Development East, LLC (Greystar), Hart & Hickman, PC (H&H) has
prepared this revised letter to request that the North Carolina Department of Environmental Quality
(DEQ) Brownfields Program provide approval for proposed modifications to the vapor intrusion
mitigation plan (VIMP) prepared for the Action Jackson Aftermarket and Car Care Automotive
Service and Repair (AJACC Auto) DEQ Brownfields Program property (Brownfields Project No.
24054-20-060) located at 301 Verbena Street in Charlotte, Mecklenburg County, North Carolina
(Site). A multi-family residential apartment complex is under construction at the Site and the
development is known as Elan LoSo.

On March 29, 2022, the Brownfields Program provided approval for the Vapor Intrusion
Mitigation Plan – Revision 1 dated March 15, 2022, related to installation of vapor mitigation
controls during construction of the Elan LoSo multi-family residential building. In accordance
Mr. Peter Doorn
August 18, 2022
Page 2
https://harthick.sharepoint.com/sites/MasterFiles-1/Shared Documents/AAA-Master Projects/Greystar, LLC (GSL)/GSL-004 Elan
LoSo/VIMP/VIMP Modifications/24054-20-060_VIMS Mod Request_Elan LoSo_08-18-22 - Rev.1.docx
with the approved VIMP, a passive vapor intrusion mitigation system (VIMS) is being installed
during construction of the building. The proposed VIMS modification is described in the
following paragraphs.

Amenity Spaces Adjacent to Open-Air Parking Garage
The DEQ-approved VIMP includes installation of the Raven Industries VaporBlock Plus 20-mil
vapor barrier (VBP20) along the vertical concrete wall between existing soils below the concrete
slab of the open-air parking garage that is adjacent to an enclosed recycling room and bike storage
room as shown on Drawing No.1 embedded below (VM-B.1 of the VIMP). These rooms are
enclosed amenity rooms inside of the parking deck that are not designed as living spaces.
However, as a precaution, these rooms are also receiving VIMS controls including vent piping
below the slab, and a vapor barrier below the slab and along vertical walls adjacent to soil as shown
in the VIMP.

In lieu of installing the vapor barrier along the soil side (exterior) of the southern concrete wall, it
is proposed to install the vapor barrier on the interior portion of the concrete wall as shown on
Drawing No. 2 embedded below. The reason for the proposed modification is due to technical
difficulty and accessibility expressed by the construction contractor to install the vapor barrier on
the exterior of the wall from conflict with the existing parking deck structure and slabs.

The proposed installation will include adhering the Raven Industries VBP-20 vapor barrier to the
interior side of the concrete wall within the southern portion of the rooms using manufacturer
approved tape and sealants. The vapor barrier will overlap and be sealed to top of the concrete
prior to the pouring of the grade level slab. The vapor barrier within the recycling room will wrap
around the adjoining perpendicular walls by a minimum of 6-inches and be sealed with
manufacturer approved tape and sealants. Additionally, the interior vapor barrier will be sealed to
the sub-slab vapor barrier utilizing a manufacturer approved tape. After installation of the vapor
barrier, the construction contractor will construct a stud wall with an air gap (approximately several
inches wide) between the stud wall and the foundation wall to protect the vapor barrier from
Mr. Peter Doorn
August 18, 2022
Page 2
https://harthick.sharepoint.com/sites/MasterFiles-1/Shared Documents/AAA-Master Projects/Greystar, LLC (GSL)/GSL-004 Elan
LoSo/VIMP/VIMP Modifications/24054-20-060_VIMS Mod Request_Elan LoSo_08-18-22 - Rev.1.docx
surficial abrasions or penetrations that could be caused by stud imperfections, nails, or general
construction activities. Should a penetration through the vapor barrier be required due to support
systems or if the vapor barrier is damaged during installation, the area will be properly sealed with
manufacturer approved vapor barrier patches and/or mastics. Prior to the installation of insulation
and drywall, a vapor barrier inspection will be completed by H&H to assess that the vapor barrier
was properly installed and holes, tears, or damage are repaired prior to covering the vapor barrier.
Once the vapor barrier inspection has been deemed acceptable, the completed stud wall will be
finished with insulation and drywall.

Note, the eastern wall of the bike storage room will receive vapor barrier between the concrete
wall and soils as proposed in the VIMP so no modification to the eastern wall is proposed. In
addition, the western and northern walls do not contain walls adjacent to soil backfill that will
warrant vapor barrier. Therefore, the sub-slab vapor barrier detail as shown on Drawing No. 3
embedded below (Detail 12/VM-1 of the VIMP) will also not require modification from the DEQ-
approved VIMP.

Drawing No. 1 – View of the proposed modification area at the southern portion of the recycling
room from Drawing VM-B.1 in VIMP.
Mr. Peter Doorn
August 18, 2022
Page 2
https://harthick.sharepoint.com/sites/MasterFiles-1/Shared Documents/AAA-Master Projects/Greystar, LLC (GSL)/GSL-004 Elan
LoSo/VIMP/VIMP Modifications/24054-20-060_VIMS Mod Request_Elan LoSo_08-18-22 - Rev.1.docx

Drawing No. 2 – View of the proposed modification from Detail 20/VM-1A of the VIMP showing
the new vapor barrier location in red.

Drawing No. 3 – View of western portion of the recycling room that will only contain sub-slab
vapor barrier from Detail 12/VM-1 in the VIMP. No change to the approved VIMP.
Mr. Peter Doorn
August 18, 2022
Page 2
https://harthick.sharepoint.com/sites/MasterFiles-1/Shared Documents/AAA-Master Projects/Greystar, LLC (GSL)/GSL-004 Elan
LoSo/VIMP/VIMP Modifications/24054-20-060_VIMS Mod Request_Elan LoSo_08-18-22 - Rev.1.docx
Upon approval of this vapor barrier modification, the details described above will be incorported
into the construction documents and after installation the installed details will be included in the
as-built drawings as part of the VIMS installation report that will be submitted to DEQ.

Engineer’s Certification
According to the DWM Vapor Intrusion Guidance: “Risk-based screening is used to identify sites
or buildings likely to pose a health concern, to identify buildings that may warrant immediate
action, to help focus site-specific investigation activities or to provide support for building
mitigation and other risk management options including remediation.” In addition, this VIMP was
prepared to satisfy the vapor intrusion mitigation condition in the pending Brownfields Agreement.
Per the North Carolina Brownfields Property Reuse Act 130A-310.32, a prospective developer,
with the assistance of H&H for this project, is to provide NCDEQ with “information necessary to
demonstrate that as a result of the implementation of the brownfields agreement, the brownfields
property will be suitable for the uses specified in the agreement while fully protecting public health
and the environment instead of being remediated to unrestricted use standards.” It is in the context
of these risk-based concepts that H&H’s professional engineer makes the following statement.

The Vapor Intrusion Mitigation System (VIMS) detailed herein is designed to mitigate intrusion
of subsurface vapors into the subject building from known Brownfields Property contaminants in
a manner that is in accordance with the most recent and applicable guidelines including, but not
limited to, DWM Vapor Intrusion Guidance, Interstate Technology & Regulatory Council (ITRC)
guidance, and American National Standards Institute (ANSI)/American Association of Radon
Scientists and Technologists (AARST) standards. The sealing professional engineer below is
satisfied that the design is fully protective of public health from known Brownfields Property
contaminants.

Mr. Peter Doorn
August 18, 2022
Page 2
https://harthick.sharepoint.com/sites/MasterFiles-1/Shared Documents/AAA-Master Projects/Greystar, LLC (GSL)/GSL-004 Elan
LoSo/VIMP/VIMP Modifications/24054-20-060_VIMS Mod Request_Elan LoSo_08-18-22 - Rev.1.docx
We appreciate your review and of the proposed modifications to the VIMS design. If you have
any questions or require additional information, please do not hesitate to contact me at 704-586-
0007.
Sincerely,

Hart & Hickman, PC

Trinh DeSa, PE
Engineering Manager

cc: Mr. Andrew Besu (H&H)
Mr. David Kahn (H&H)
Mr. Kelly Johnson (NC DEQ)