2022.03.25_CCOA.p3b_90% Design Report Cover Letter

The Chemours Company
Fayetteville Works
22828 NC Highway 87 W
Fayetteville, NC 28306

March 25, 2022
Sushma Masemore, P.E.
Deputy Assistant Secretary for Environment & State Energy Director
1601 Mail Service Center
Raleigh, NC 27699-1601
[e-mail]

Re: Submission of Barrier Wall and Groundwater Extraction System 90%
Design Report, Chemours Fayetteville Works, Fayetteville, NC
Dear Ms. Masemore,
Chemours is submitting the Barrier Wall and Groundwater Extraction System 90% Design
Report. This report has been prepared pursuant to Paragraph 3.b in the Addendum to Consent
Order Paragraph 12 entered by the Bladen County Superior Court on October 12, 2020, which is
incorporated into the terms of the Consent Order entered February 25, 2019 between Chemours
and the North Carolina Department of Environmental Quality (DEQ) with the Cape Fear River
Watch (CFRW). The report was prepared by Chemours’s consultants, Geosyntec Consultants of
NC, P.C. and GEOServices, LLC.

The core elements of the design presented in this report were previously included in the
60% Design Report submitted August 13, 2021, which was approved by DEQ. The 90% Design
Report contains additional and more detailed design parameters and minor modifications based
on additional data and DEQ comments. The core elements remain a barrier wall over 6,000 feet
in length (with the same contours as in the 60% Design Report), hydraulic containment of
groundwater and seeps behind the wall and to the north of the wall along Willis Creek, and the
installation of a water treatment plant to treat groundwater and Seep water as required in the
Consent Order Addendum.

Additional items included in this report include a Barrier Wall Construction Quality
Assurance Plan and a Remedy Performance Monitoring Plan (PMP). These plans were requested
by DEQ in comments on the 60% Design Report. Chemours submitted these plans to DEQ in
January, 2022. On February 15, 2022 DEQ provided additional comments on these plans.
Chemours submitted a Response to Comments on these plans on March 17, 2022 and, as part of
today’s submission of the 90% Design Report, is incorporating changes to both plans as proposed
in the Response to Comments from March 17, 2022 with one exception. Chemours had proposed
that river transect sampling identified by DEQ be included in the PMP in conjunction with other
sampling to show performance of the barrier wall and extraction system remedy. However, as
DEQ has included a river transect sampling requirement in the draft NPDES permit for the water
treatment system, such sampling has been removed from the PMP.

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If you have any questions, please contact me at [e-mail].

Sincerely,

Dawn M. Hughes
Plant Manager
Chemours – Fayetteville Works

Enclosure
Barrier Wall and Groundwater Extraction System 90% Design Report

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Cc:
Sushma Masemore, DEQ
William F. Lane, DEQ
Francisco Benzoni, NC DOJ
Michael Abraczinskas, DAQ
Michael Scott, DWM
Richard Rogers, DWR
Julie Grzyb, DWR
Sergei Chernikov, DWR
David C. Shelton, Chemours
John F. Savarese, WLRK
Kemp Burdette, CFRW
Geoff Gisler, SELC
Todd Coomes, Chemours
Kevin Garon, Chemours
Christel Compton, Chemours
Joel Gross, Arnold & Porter
Thomas Santoro, Arnold & Porter
Alyssa Wright, DEQ
Holly Ingram, DEQ