2019.11.04_CCO.p12_SupplementalReportCoverLetter

The Chemours Company
Fayetteville Works
22828 NC Highway 87 W
Fayetteville, NC 28306
November 4, 2019
Sheila Holman
Assistant Secretary for the Environment
1601 Mail Service Center
Raleigh, NC 27699-1601
[e-mail]
Kemp Burdette
Cape Fear River Watch
617 Surry Street
Wilmington, NC 28401
[phone]
[e-mail]
Re: Cape Fear River PFAS Loading Reduction Plan - Supplemental Information
Report
Dear Ms. Holman and Mr. Burdette,
On August 26, 2019, Chemours submitted the Cape Fear River PFAS Loading Reduction
Plan, pursuant to paragraph 12 of the Consent Order entered by the Superior Court for Bladen
County on February 25, 2019. The enclosed Supplemental Information Report, prepared by
Geosyntec Consultants of NC, P.C. (Geosyntec) and Parsons of NC (Parsons), provides
supplemental information to support the evaluation of remedial options to reduce loadings of
PFAS originating from the Chemours Fayetteville Works Site (the Site) to surface waters
surrounding the Site including the Cape Fear River, Willis Creek, Georgia Branch Creek and Old
Outfall 002. As with the August 26 submission, Chemours is simultaneously transmitting this
submission to downstream public water utilities.
Sincerely,
Brian D. Long
Plant Manager
Chemours – Fayetteville Works

2
Enclosure
Cape Fear River PFAS Loading Reduction Plan - Supplemental Information Report

Cc:
William F. Lane, DEQ
Francisco Benzoni, NC DOJ
Michael Abraczinskas, DAQ
Michael Scott, DWM
Linda Culpepper, DWR
David C. Shelton, Chemours
John F. Savarese, WLRK
Geoff Gisler, SELC
Downstream Public Water Utilities

CAPE FEAR RIVER PFAS LOADING
REDUCTION PLAN –
SUPPLEMENTAL INFORMATION
REPORT
Chemours Fayetteville Works

Prepared for
The Chemours Company FC, LLC
22828 NC Highway 87
Fayetteville, NC 28306 910-678-1315
Prepared by
Geosyntec Consultants of NC, PC 2501 Blue Ridge Road, Suite 430 Raleigh, NC 27607
Parsons 4701 Hedgemore Dr Charlotte, NC 28209
Geosyntec Project Number TR0795
November 2019

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TABLE OF CONTENTS
1 INTRODUCTION ................................................................................................ 1
1.1 Actions Implemented ................................................................................... 2
1.2 Overview of Remedial Selection Process .................................................... 2
1.3 Document Organization ............................................................................... 3
2 REMEDIAL ALTERNATIVE IDENTIFICATION AND SELECTION
PROCESS ............................................................................................................. 4
2.1 Remedial Objectives .................................................................................... 4
2.2 Identify Remedial Alternatives .................................................................... 4
2.3 Compare Remedial Alternatives .................................................................. 4
2.4 Assessment Criteria 1 – Environmental Protection ..................................... 5
2.5 Assessment Criteria 2 – Adverse Environmental Effects ............................ 5
2.6 Assessment Criteria 3 – Technical Feasibility ............................................ 6
2.7 Assessment Criteria 4 – Timeframe ............................................................ 6
2.8 Assessment Criteria 5 – Economic Feasibility ............................................ 7
2.9 Selection Process ......................................................................................... 7
3 DESCRIPTION OF REMEDIAL ALTERNATIVES .......................................... 9
3.1 Pathway: Direct Aerial Deposition ............................................................ 12
3.1.1 Control Technology Improvements to Reduce Aerial Emissions . 13
3.2 Pathway: Old Outfall 002 .......................................................................... 14
3.2.1 Capture and Treat at Old Outfall 002 ............................................ 15
3.3 Pathway: Groundwater Seeps .................................................................... 16
3.3.1 Interim Remedial Alternative for Seeps: Flow-Through Cells ..... 19
3.3.2 Interim Remedial Action for Seeps: Ex Situ Capture French Drains
21
3.3.3 Interim Remedial Action for Seeps: PlumeStop™ ...................... 23
3.3.4 Permanent Remedial Alternative for Seeps: Flow-Through Cells 25
3.3.5 Permanent Remedial Alternative for Seeps: Ex Situ Capture
French Drains ............................................................................................ 25
3.3.6 Permanent Remedial Alternative for Seeps: PlumeStop™ .......... 25
3.4 Pathway: Onsite Black Creek Aquifer Groundwater ................................ 26
3.4.1 Interim Alternatives Groundwater Extraction from Existing
Monitoring Wells ...................................................................................... 26

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3.4.2 Interim Alternative Groundwater Extraction from Additional
Extraction Wells ....................................................................................... 28
3.4.3 Permanent Remedies for Onsite Groundwater: Extraction with
Vertical Extraction Wells ......................................................................... 29
3.4.4 Permanent Groundwater Remedy: Barrier Wall and Groundwater
Capture ...................................................................................................... 32
3.5 Pathway: Outfall 002 ................................................................................. 34
3.5.1 Conveyance Network Sediment Removal .................................... 35
3.5.2 Stormwater Pollution Prevention Plan .......................................... 35
3.5.3 Targeted Stormwater Control ........................................................ 37
3.5.4 Terracotta Pipe Decommissioning ................................................ 42
3.5.5 Mitigation of Groundwater Intrusion into Outfall 002 ................. 44
3.5.6 Treatment of all Stormwater at Outfall 002 .................................. 45
3.5.7 Treatment of all Flows at Outfall 002 ........................................... 48
3.6 Pathway: All Loadings From Willis Creek and Georgia Branch Creek .... 50
3.6.1 Capture and Treatment at Mouths of Creeks ................................ 50
3.6.2 Application of PlumeStop™ to Length of Willis Creek and
Georgia Branch Creek .............................................................................. 52
3.7 Pathway: Offsite Groundwater .................................................................. 53
3.7.1 Hydraulic Containment and Treatment ......................................... 53
4 ASSESSMENT OF REMEDIES ........................................................................ 56
4.1 Old Outfall 002 .......................................................................................... 56
4.2 Groundwater Seeps .................................................................................... 58
4.3 Onsite Black Creek Aquifer Groundwater ................................................ 60
4.4 Outfall 002 ................................................................................................. 62
4.5 Willis Creek and Georgia Branch Creek ................................................... 64
4.6 Cost vs. Performance Assessment of Alternatives .................................... 66
4.7 Offsite Groundwater .................................................................................. 70
5 PROPOSED SEEPS INTERIM ACTIONS AND ALTERNATIVE
SELECTION SEQUENCE ................................................................................. 72
5.1 Proposed Interim Actions .......................................................................... 72
5.2 Alternative Selection Sequence ................................................................. 72
6 PROPOSED ONSITE GROUNDWATER INTERIM ACTIONS AND
ALTERNATIVE SELECTION SEQUENCE .................................................... 74

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6.1 Proposed Interim Actions .......................................................................... 74
6.2 Alternative Selection Sequence ................................................................. 74
7 SUMMARY ........................................................................................................ 76
8 REFERENCES ................................................................................................... 78

LIST OF TABLES
Table 1: Estimate of PFAS Mass Loading from the facility on a per-pathway basis. ...... 9
Table 2: Remedial Alternatives Considered in Supplemental Action Plan .................... 11
Table 3: PFAS Loading from Seeps and in Willis Creek ............................................... 17
Table 4: Assessment of Old Outfall 002 Alternatives .................................................... 57
Table 5: Assessment of Groundwater Seep Alternatives ............................................... 59
Table 6: Assessment of Onsite Black Creek Aquifer Groundwater Alternatives .......... 61
Table 7: Assessment of Outfall 002 Alternatives ........................................................... 63
Table 8: Assessment of Willis and Georgia Branch Creek Alternatives ........................ 65
Table 9: Cost Benefit Summary for Remedy Scenario Evaluation ................................ 67
Table 10: Assessment of Offsite Groundwater Alternative ............................................ 71
Table 11: Schedule for Proposed Interim Actions for Seeps .......................................... 73
Table 12: Implementation schedule for On-Site Groundwater ....................................... 75
Table 13: Overall Estimated Reductions Plan Schedule and Reductions to Cape Fear
River Total Table 3+ PFAS Loadings ............................................................................ 77

LIST OF FIGURES
Figure 1: Schematic Conceptual Site Model of the Site including geological layers, and
PFAS transport pathways ............................................................................................... 10
Figure 2: October 2019 Image of Thermal Oxidizer Structure During Construction. ... 14
Figure 3. Old Outfall 002 Treatment System Process Flow Diagram ............................ 15
Figure 4: Location of Potential Seep Remedies ............................................................. 18
Figure 5: Conceptual Diagram of Seep Flow Through Passive Treatment .................... 20
Figure 6: Conceptual Diagram of Seep French Drain Ex Situ Capture .......................... 22

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Figure 7: Location of potential interim PlumeStop™ applications for groundwater seeps
originating from Perched Zone groundwater flow. ........................................................ 24
Figure 8: Potential Black Creek Monitoring Wells for Interim Action of Extraction and
Treatment ........................................................................................................................ 27
Figure 9: Conceptual Layout of Onsite Groundwater Extraction Remedy .................... 31
Figure 10: Conceptual Layout of Onsite Groundwater Extraction Remedy Behind Barrier
Wall ................................................................................................................................. 33
Figure 11: Sediment removal from Open Channel on October 15, 2019 ....................... 35
Figure 12. Example Erosion Control Measure (fiber rolls) ............................................ 37
Figure 13. Targeted Stormwater Treatment Design Concept ......................................... 40
Figure 14. Targeted Stormwater Treatment .................................................................... 41
Figure 15: Terracotta Piping Layout ............................................................................... 43
Figure 16: Surveyed elevations of the bottom of the Open Channel to Outfall 002 ...... 45
Figure 17. All Site Stormwater Treatment ..................................................................... 47
Figure 18. All Outfall 002 Treatment ............................................................................. 49
Figure 19: Willis Creek and Georgia Branch Creek Drainage Areas and Hypothetical
Capture Locations ........................................................................................................... 51
Figure 20: Conceptual Layout of a Hypothetical Offsite Groundwater Remedy ........... 54
Figure 21: Cost-Benefit Analysis (Cumulative – Zoomed in x-axis extent) For Remedial
Alternative with Conceptual Costs ................................................................................. 68
Figure 22: Cost-Benefit Analysis (Cumulative – Full x-axis extent) For Remedial
Alternative with Conceptual Costs ................................................................................. 69

LIST OF APPENDICES
Appendix A: Remedy Costing Tables

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LIST OF ABBREVIATIONS
% percent µg/s micrograms per second µm micrometers BMP best management practice
CAP Corrective Action Plan
CFRW Cape Fear River Watch EAA Engineering Alternatives Analysis EQ influent equalization ft feet
ft bgs feet below ground surface
GAC granular activated carbon gabions large wire baskets gpm gallons per minute HDPE high-density polyethylene
HFPO-DA Hexafluoropropylene oxide dimer acid
IPC inclined plate clarifier MMF multimedia filtration NCCW non-contact cooling water NCDEQ North Carolina Department of Environmental Quality
NPDES National Pollutant Discharge Elimination System
NPV net present value ng/L nanogram per liter OOF2 Old Outfall 002 PFAS per- and polyfluoroalkyl substances
PFMOAA perfluoro-1-methoxyacetic acid
PMPA Perfluoromethoxypropyl carboxylic acid ROM rough order of magnitude SWPPP Stormwater Pollution Prevention Plan TRD Trench cutting and Remixing Deep
TSS total suspended solids
USACE United States Army Corps of Engineers WWTP wastewater treatment plant

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1 INTRODUCTION
The Cape Fear River PFAS Loading Reduction Plan (Geosyntec, 2019a) was submitted
to the North Carolina Department of Environmental Quality (NCDEQ) and Cape Fear
River Watch (CFRW) on August 26, 2019 pursuant to Paragraph 12 of the Consent Order
among Chemours, NCDEQ, and (CFRW). This report (“Supplemental Report”) was
prepared by Geosyntec Consultants of NC, P.C. (Geosyntec) and Parsons of NC (Parsons)
for The Chemours Company FC, LLC (Chemours) and provides supplemental
information to support the evaluation of remedial options to reduce per- and
polyfluoroalkyl substances (PFAS) originating from the Chemours Fayetteville Works
Site (the Site) to surface waters surrounding the Site including the Cape Fear River, Willis
Creek, Georgia Branch Creek and Old Outfall 002. Further, this Supplemental Report
was prepared in response to comments on the Reduction Plan by NCDEQ and the CFRW,
provided to Chemours in letters dated September 26, 2019 and October 23, 2019.
This Supplemental Report provides information regarding proposed remedies presented
in the Reductions Plan submitted on August 26, 2019 (Seeps, Outfall 002, Old Outfall
002, Georgia Branch Creek, Willis Creek and Offsite Groundwater). In addition, this
Supplemental Report also provides information on:
• potential interim alternatives to reduce PFAS mass loadings from onsite seeps
and onsite groundwater to the Cape Fear River on an accelerated timeframe;
• provisional remedial alternatives under consideration and subject to more
extensive evaluation to reduce onsite groundwater PFAS mass loading to the
Cape Fear River1; and
• remedial alternatives that were considered but not proposed.

The Reduction Plan (Geosyntec 2019a) did not previously identify onsite groundwater
PFAS treatment options, other than those for Old Outfall 002 and the Seeps; assessment
activities were still ongoing. This evaluation will be the principal focus of the Corrective
Action Plan (CAP) to be submitted in December 2019. A working conceptual site model

1 The onsite groundwater remedy approaches presented here are provisional. Chemours’s consultants have been preparing a numerical groundwater model to evaluate Site groundwater flows and will use this model to evaluate the technological feasibility of potential groundwater control options. The results of the model and the implications for the finalization of actions for expedited reductions of PFAS loadings to surface water will be provided in conjunction with the Corrective Action Plan due December 31, 2019.

TR0795 2 November 2019
has been recently developed and data gaps are being considered and assessed. The current
site conceptual model was outlined in the On and Offsite Assessment Report on
September 30, 2019 (Geosyntec, 2019b) and updated on October 31, 2019.This document
provides a proposed schedule for further development, implementation and optimization
of such reduction measures.
1.1 Actions Implemented
Actions already implemented by Chemours have reduced yearly HFPO-DA mass
loadings from the facility to the environment by at minimum 5,150 pounds per year
(lbs/yr) compared to pre-June 2017 emissions and discharges (Geosyntec 2019a). Air
emission reductions to date, on an annualized basis for 2019, have resulted in an estimated
yearly reduction of 2,150 pounds of HFPO-DA, a greater than 93% reduction. Cessation
of Chemours process water discharge to Outfall 002 resulted in at minimum an estimated
yearly reduction of 3,000 lbs/yr of HFPO-DA. These actions have reduced HFPO-DA
mass loadings, through Outfall 002, by over 99% from June 2017 levels (Geosyntec
2019a). This has resulted in reductions of HFPO-DA to the Cape Fear River. Present
estimates of HFPO-DA mass loading to the Cape Fear River from all pathways are
between 64 and 129 pounds per year (lbs/yr). This represents upwards of a 95% reduction
in mass loading to the Cape Fear River from all pathways (Geosyntec 2019a).
Chemours has also implemented multiple actions to further reduce loading of PFAS to
the Cape Fear River as outlined in the Reduction Plan (Geosyntec, 2019a).
These reductions will be further enhanced by implementation of the Thermal Oxidizer by
the end of 2019, which will control over 99.99% of PFAS emissions routed to it, and the
actions proposed in this plan will further reduce HFPO-DA and other PFAS loadings to
the environment.
Outfall 002 loading rates in 2019, integrating both dry and wet weather periods, are
presently 8% lower than in calendar year 2018. This reduction is potentially a result of
various completed actions at the Site, including reduced air emissions. Loading at Outfall
002 is expected to continue a downward trajectory year over year.
Actions outlined in this supplemental report are generally intended to address PFAS that
is present in soil and groundwater from historical operations.
1.2 Overview of Remedial Selection Process
The process of selecting remedial alternatives is based on numerous factors, including the
Site setting, the nature of the compounds of concern and potential receptors and
technological and economic feasibility. At the Site, Table 3+ PFAS are present in many

TR0795 3 November 2019
areas. These are relatively recent compounds being considered for environmental
remediation and as such there are few treatment technologies with full-scale
demonstrations of effectiveness. PFAS remediation is a rapidly evolving field and new
technologies may become available and suitable for the PFAS at the Site that would
expand the set of alternatives available for consideration. Therefore, the set of remedial
alternatives considered for this Site are subject to enhancement over time.
1.3 Document Organization
The remainder of this Supplemental Report contains an overview of the evaluation
process for potential remedies (Section 2); a description of the remedial alternatives
(Section 3); the assessment of alternatives against the criteria, including alternatives not
selected (Section 4); selection of interim remedial alternatives for seeps (Section 5);
selection of interim remedial alternatives for onsite Black Creek Aquifer groundwater
(Section 6); a summary (Section 7); and report references are provided in Section 8.

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2 REMEDIAL ALTERNATIVE IDENTIFICATION AND SELECTION
PROCESS
The following process may be used to identify remedial approaches to advance, and is
described herein for the evaluation to reduce PFAS originating from the Site:
1) Define Remedial Objectives
2) Identify Remedial Alternatives
3) Compare Remedial Alternatives
2.1 Remedial Objectives
Consistent with Paragraph 12 of the Consent Order, the following three Remedial
Objectives are appropriate for interim actions and actions considered as part of the
Reductions Plan (Geosyntec 2019a):
i. Reduce PFAS Mass Loading to the Cape Fear River
ii. Reduce PFAS Mass Loading to Willis Creek, Georgia Branch Creek and
Old Outfall 002; and
iii. Identify alternatives to provide maximum loading reductions in two years,
and if greater reductions can be achieved consider up to a five-year
implementation period.
Further, proposed interim measures may ultimately integrate into the overall remedies.
The objectives of the remedies will include, in addition to the above criteria, protecting
human health and the environment and compliance with groundwater standards or
alternate groundwater standards using criteria from 15A NCAC 02L.
2.2 Identify Remedial Alternatives
Remedial alternatives were identified which could satisfy the remedial objectives for each
PFAS Mass Loading Pathway identified in the Cape Fear River PFAS Mass Loading
Model submitted to DEQ and CFRW (Geosyntec, 2019c). The remedial alternatives
identified by this process are described in Section 3.
2.3 Compare Remedial Alternatives
Remedies can be assessed and scored for the following criteria:
i. Environmental Protection (i.e. reduction of PFAS Mass Loading);
ii. Adverse Environmental Effects;
iii. Technical Feasibility;
iv. Timing (i.e., 2 years or 5 years); and

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v. Economic Feasibility (i.e., reduction achieved per relative cost expended).
These criteria recognize the adverse impacts may result during remediation and that
selected alternatives must be both technologically and economically feasible. The
following sub-sections describe each assessment criteria and how it was scored on a scale
of 1 to 5 where 1 was the most favorable score and 5 the least favorable score.
2.4 Assessment Criteria 1 – Environmental Protection
Remedial alternatives were assessed to establish the expected degree of loading reduction
they would provide to the Cape Fear River, Willis Creek, Georgia Branch Creek, and
Outfall 002. For each waterbody based on professional engineering and scientific
judgement and analyses of the alternatives presented in this Supplemental Report, the
alternatives were assigned scores as follows:
Total Table 3+
PFAS Mass Loading Reductions to Surface Water Body
Scoring
>20% 1
>10 - 20% 2
>5 - 10% 3
>2 - 5% 4
0 - 2% 5

2.5 Assessment Criteria 2 – Adverse Environmental Effects
Remedial alternatives were assessed to establish the potential degree of adverse
environmental effects they might cause (e.g. habitat destruction). Based on professional
engineering and scientific judgement and analyses of the alternatives presented in this
Supplemental Report were assigned scores as follows:

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Adverse Environmental Effect Scoring
No anticipated local effect 1
Some destruction of local habitat 2
Some alteration to local waterbody 3
Habitat destruction or alteration over a large extent 4
Extensive destruction of habitat type or waterbody 5

2.6 Assessment Criteria 3 – Technical Feasibility
Remedial alternatives were assessed to establish their potential technical feasibility.
Based on professional engineering and scientific judgement and analyses of the
alternatives presented in this Supplemental Report were assigned scores as follows:
Technical Feasibility Criteria Scoring
Simple to Implement 1
Some Challenges,
Success Fairly Certain 2
Complex or Large, Some Uncertainty about Degree of Success 3
Complex, Large, Access Issues, Success Potentially Possible 4
Complex, Large, Access Issues, Success Unlikely 5

2.7 Assessment Criteria 4 – Timeframe
Remedial alternatives were assessed to establish the timeframes in which they could be
implemented. Based on professional engineering and scientific judgement and analyses
of the alternatives presented in this Supplemental Report were assigned scores as follows:

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Time To Implement Scoring
Up to 1 year 1
From 1 to 2 years 2
>2 - 3 years 3
>3 - 5 years 4
> 5 years 5

2.8 Assessment Criteria 5 – Economic Feasibility
Remedial alternatives were assessed to establish their economic feasibility, where
feasibility was established using the metric of cost in millions of dollars per reduction of
one percent of Total Table 3+ PFAS Loading to the Cape Fear River. Based on the
reductions to the Cape Fear River for each alternative and the estimated costs of each
were assigned scores as follows:
Cost (Millions of Dollars) to achieve a 1% Reduction in Cape Fear River Total Table 3+ PFAS Loading
Scoring
$0 - $1M 1
>$1M - $2.5M 2
>$2.5M - $5M 3
>$5M - $10M 4
>$10M 5

2.9 Selection Process
Chemours is committed to taking actions to achieve expedited loading reduction for
groundwater seeps and onsite groundwater, and the feasibility of each is evaluated in this
Supplemental Report. The remedial alternatives for these pathways are still undergoing
a final remedy selection process, as the technical evaluation of these options is in progress
as described in Sections 5 and 6.
For remedies considered as part of the Reduction Plan (Geosyntec 2019a), selection is
advanced herein as follows:

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• Step 1: Initial screening
• Step 2: Selection of several viable remedial alternatives per pathway
In Step 1, alternatives with scores of 5, the least favorable score, for criteria 2, 3 and 5
(adverse impacts, technical feasibility and economic feasibility) were removed from the
selection process.

Criteria Action
1 – Achieves Reductions All remedies regardless of scores are advanced
2 – Adverse Impacts Remedies with a score of 5 are removed from selection process
3 – Technical Feasibility Remedies with a score of 5 are removed from selection process
4 – Implementation Timing All remedies regardless of scores are advanced
5 – Economic Feasibility Remedies with a score of 5 are removed from selection process
If a proposed remedial alternative would cause severe adverse environmental impacts, it
was not advanced as the purpose of remediation is to protect human health and improve
environmental quality. If a remedy was infeasible, in other words if it was scored as 5, it
was not advanced as it would not be implementable. If two proposed alternatives
effectively achieved the same goals, the lower cost remedy was advanced. If a remedy
was economically infeasible, i.e. it did not provide benefit that was commensurate with
the cost to implement the remedy, it was not advanced for consideration. In Step 2,
remedies were selected for further evaluation after balancing perspectives from all criteria
presented here, comparison against remedial objectives and using professional
engineering and scientific judgement.
Ultimately, those remedial options selected to advance will require further evaluation in
the context of how the remedy integrates into the longer-term remedial approach. The
additional evaluation includes groundwater flow modeling and the empirical studies
currently underway.

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3 DESCRIPTION OF REMEDIAL ALTERNATIVES
In the Reduction Plan, nine PFAS transport pathways to the Cape Fear River were
identified, and were generally organized from upstream to downstream, as shown below
in Table 1, which also includes the estimated mass loading of PFAS per pathway based
on two sampling events. Additional quarterly sampling events are being conducted, and
the mass loading model will be updated to adjust the model for variability over time.
Figure 1 is a schematic conceptual site model of the pathways. For each of the pathways,
a number of treatment options have been identified for evaluation and associated
approaches in Table 2.
Table 1: Estimate of PFAS Mass Loading from the facility on a per-pathway basis.
Pathway
Total Table 3+ Estimated Loading Percentage per Pathway per Event May 2019 Event June 2019 Event
[1] Upstream River Water and Groundwater* 4% 15%
[2] Willis Creek 10% 4%
[3] Aerial Deposition on the River < 2% < 2%
[4] Outfall 002 4% 7%
[5] Onsite Groundwater 22% 17%
[6] Seeps 32% 24%
[7] Old Outfall 002 23% 29%
[8] Offsite Adjacent and Downstream Groundwater* < 2% < 2%
[9] Georgia Branch Creek 4% 3%
* Pathways 1 and 8 (upstream river and groundwater; adjacent and downstream groundwater) are assessed together in this Supplemental Report as “offsite groundwater” ..
.

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Figure 1: Schematic Conceptual Site Model of the Site including geological layers, and PFAS transport pathways

TR0795 11 November 2019

Table 2: Remedial Alternatives Considered in Supplemental Action Plan

For each proposed alternative, the following sections provide a detailed description,
estimated reduction in PFAS that may be achievable, implementation schedule, and
estimated cost.
Construction and annual operating costs for each alternative have been estimated with a
range of -30 % to +50 %, and the 20-year net present value (NPV) is estimated at a 3.5%
discount rate. Cost estimates are not intended for budgetary or future planning purposes;
Pathway Potential Treatment Approach Sub-Section Direct Aerial Deposition Air Emission Control Technologies 3.1.1
Old Outfall 002 Capture and Treat Old Outfall 002 3.2.1
Seeps
Flow Through Cells CFR Seeps - Interim 3.3.1
Ex Situ Capture and Treatment CFR Seeps - Interim 3.3.2
Plume Stop CFR Seeps A and B - Interim 3.3.3
Flow Through Cells CFR Seeps 3.3.4
Flow Through Cells Willis Creek Seeps 3.3.4
Ex Situ Capture and Treatment CFR Seeps 3.3.5
PlumeStop Willis Creek Seeps 3.3.6
Onsite Groundwater
Extract from Black Creek Monitoring Wells - Interim 3.4.1
Install New Black Creek Extraction Wells - Interim 3.4.2
Groundwater Extraction 3.4.3
Groundwater Extraction with Barrier Wall 3.4.4
Outfall 002
Conveyance Network Sediment Removal 3.5.1
Stormwater Pollution Prevention Plan 3.5.2
Targeted Stormwater Control 3.5.3
Terracotta Pipe Decommissioning 3.5.4
Groundwater Intrusion Mitigation 3.5.5
Treat all stormwater at Outfall 002 3.5.6
Treat all flows at Outfall 002 3.5.7
Willis and Georgia Branch Creeks
Treat all Flows at Willis Creek & Georgia Branch Creek Mouths 3.6.1
PlumeStop™ along Willis Creek & Georgia Branch Creek Lengths 3.6.2
Offsite Groundwater Groundwater Extraction with Barrier Wall 3.7.1
Air Emission Control Technologies 3.1.1

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they have been prepared from the currently available information to facilitate an inter-
alternative comparison. The final costs of any selected alternative will depend on final
approved design, actual labor and material costs, and competitive variable factors.
A distinction has been made between cost estimates that are considered rough order of
magnitude (ROM) versus costs that are considered conceptual. For remedies that are
already in development or are intended to be implemented, including those previously
described in the Reduction Plan, ROM costs have been prepared as the scope of these
remedies can be defined somewhat reliably. For remedies that have been conceptualized
herein without sufficient design inputs like the numerical groundwater model , the cost
estimates are considered conceptual. Detailed backup sheets for each of these alternatives
are provided in Appendix A.
For long-term onsite groundwater remedies, the numerical model is explicitly necessary
to develop and evaluate modeling scenarios (such as groundwater extraction behind a
barrier wall), which will generate the design inputs that are needed to develop reliable
cost estimates. As the model was not available at the time of this Supplemental Report,
possible modeling scenarios are provided, but costs were not developed, as they would
improperly inform the inter-alternative comparison. Accordingly, the onsite groundwater
remedies conceptualized herein are to be brought forward (i.e., retained), on both a long
term and expedited basis, in the following two months for detailed evaluation and
ultimately for selection in, or in conjunction with, the CAP.
Similarly, for targeted stormwater treatment, which has been previously proposed, costs
are not able to be reliably estimated at this time since the scope of treatment required and
the technologies to be implemented have not been assessed, since stormwater
investigations are ongoing. The action plan to be proposed as part of or in conjunction
with the CAP will outline the stormwater areas for potential treatment and control
technologies to pilot test and optimize.
3.1 Pathway: Direct Aerial Deposition
Direct aerial deposition of PFAS emissions from the facility has the potential to result in
mass loading to surface water bodies; however, the mass loading model estimated that
aerial deposition contributed less than 2% of the mass loading observed in the Cape Fear
River. Aerial deposition was identified as a pathway of concern primarily due to offsite
drinking water wells. The remedial approach identified to mitigate impacts to offsite
drinking water wells is a series of air emission control technologies.

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3.1.1 Control Technology Improvements to Reduce Aerial Emissions
Pursuant to Paragraph 7 of the Consent Order, Chemours completed a number of
operational improvements to control air emissions. In November 2018 Chemours
installed a packed bed scrubber to control emissions from the Division Waste Gas
Scrubber and in December 2018 Chemours completed the tie-in of the Carbon Absorber
unit for the Second Phase Scrubber at the Vinyl Ether North Plant. By December 31, 2019
Chemours is installing a Thermal Oxidizer to control air emissions of PFAS from process
streams from the Monomers IXM Area (Figure 2). As required by the Consent Order, the
thermal oxidizer will control air stream PFAS routed to it at an efficiency of 99.99%
leading to a facility wide reduction of PFAS emissions to air of 99% or greater. The
reduction of PFAS emissions to air will over time result in lower concentrations of PFAS
in offsite soils and groundwater and lead to reductions of loading to Willis Creek, Georgia
Branch Creek and the offsite Cape Fear River. The total construction cost for the thermal
oxidizer is expected to be approximately $100 million or greater (a cost detail sheet is not
provided in Appendix A as this remedy is under construction). The image below shows
the current progress of this control technology.

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Figure 2: October 2019 Image of Thermal Oxidizer Structure During Construction.
3.2 Pathway: Old Outfall 002
The Old Outfall 002 is a natural feature that discharges to the Cape Fear River. Perched
zone and surficial aquifer groundwater also discharge to this feature. Since Site
groundwater has elevated PFAS concentrations, Old Outfall 002 also has elevated PFAS
levels. The results of the Mass Loading Model indicate Old Outfall 002 is one of the
primary contributors of PFAS mass loading originating from the facility to the Cape Fear
River, estimated to contribute about 25% of observed mass loading.
The remedial approach that was identified, and which is currently in detailed design,
planning and permitting, is Capture and Treatment of Old Outfall 002 flows.

TR0795 15 November 2019
3.2.1 Capture and Treat at Old Outfall 002
Remedy Description
As described in Proposed Action 1 of the Reduction Plan, Chemours will continue to
comply with the existing Consent Order requirements by implementing an ex situ capture
and treatment remedy for Old Outfall 002. Chemours provided details on the approach
for treatment in the Old Outfall 002 Engineering Report (Parsons, 2019b) and Old Outfall
002 Engineering Alternatives Report (Parsons, 2019a). A process flow diagram of the
treatment process is shown in Figure 3. Based on the most recent flow measurements, the
dry weather baseflow at Old Outfall 002 is between 500 and 750 gallons per minute
(gpm); therefore, the facility is being designed to treat up to 750 gpm.
The treatment system is required to be constructed and operational by September 30,
2020, assuming permits are issued in a timely manner. In order to continue and accelerate
progress on implementing this remedy, Chemours is clearing the land where the Old
Outfall treatment system will be located by the end of 2019 and is arranging for power to
be available at this location by early 2020. Chemours is currently soliciting bids from
water treatment vendors to provide the treatment system.

Figure 3. Old Outfall 002 Treatment System Process Flow Diagram

TR0795 16 November 2019
Schedule

ROM Cost
The Old Outfall 002 Engineering Alternatives Analysis (EAA) presented cost estimate
ranges for the technically feasible wastewater alternatives (Parsons, 2019a); however, the
design of the system continues to progress and these costs have been refined based on
new flow measurements and data from the pilot treatment study (Parsons, 2019c).
Chemours is currently evaluating the need for iron removal at the facility which would
reduce the construction and operational requirements of the facility. Therefore, the cost
estimate was prepared without iron removal or a treatment building. Construction cost
was estimated to be $7 to 15 million, annual O&M costs are estimated to be $1 to 2
million, and the 20-year NPV is $21 to 45 million. The detailed estimate is presented in
Appendix A.

3.3 Pathway: Groundwater Seeps
Four groundwater seeps discharging from the bluff slope directly to the Cape Fear River
were identified and described in the Seeps and Creeks Investigation report (Geosyntec,
2019d). Additionally, five smaller seeps also draining into Willis Creek were identified.
The Mass Loading Model estimated that the onsite seeps discharging to the Cape Fear
River contributed between 24% to 32% of PFAS mass load; by contrast, the seeps
draining into Willis Creek are estimated to represent less than 0.4% of the mass loading
Geotechnical Investigation 2
Electrical Enabling Package 3
Electical Upgrades (EMC)6
Prepare RFP for WTP 1
Bidding and Award (WTP Only)2
Lift Station/Dam Design 2
NPDES Permitting (1)9
Lift Station/Dam Construction 3
WTP Design/Procurement 6
Startup 1
1 - Task timing is dependent upon agency approval timing
Task Duration
(months)2019 2020

TR0795 17 November 2019
of the Cape Fear River Seeps (17 / 5200 *100% = 0.33%), as calculated from the values
presented in Table 3. On this basis, the identified Willis Creek seeps represent a de
minimis source of PFAS to both Willis Creek at 2% of the load to Willis Creek (17 / 880
* 100% = 1.9%) and by extension the Cape Fear River (maximum estimate of 0.2%; 10%
maximum mass loading of Willis Creek to Cape Fear River * 2% Willis Creek Seep
Loading = 0.2%).
Table 3: PFAS Loading from Seeps and in Willis Creek
Seeps Flow Rate May 2019 (gpm)
T3+ PFAS May 2019 Concentration (ng/L)
Mass Loading (ug/s)
Seep A 120 300,000 2,270
Seep B 100 310,000 1,960
Seep C 30 350,000 660
Seep D 30 170,000 320
Total Cape Fear River Seeps 5,200
WC-1-TR2 4.4 7,100 2.0
WC-3-TR2 4.8 21,000 6.3
WC-3-TR3 3.3 4,200 0.9
WC-3-TR5 1.2 2,388 0.2
WC-4-TR1 34 3,500 7.6
Total Willis Creek Seeps 17
Willis Creek 2,900 4,800 880
Notes – Total Table 3+ PFAS concentrations come from the May 2019 sampling event reported in the Seeps and Creeks Investigation (Geosyntec, 2019d).
gpm – gallons per minute
ng/L – nanograms per liter
µg/s – micrograms per second
T3+ PFAS – Results of Table 3+ PFAS analytes summed
Three remedial alternatives were identified for reducing the PFAS Mass Loading from seeps:

TR0795 18 November 2019
• Alternative A: Passive Treatment via Flow-Through Cells;
• Alternative B: Ex Situ Capture and Treatment using French Drains or
equivalent;
• Alternative C: In Situ Treatment using PlumeStop™
Each of these options is considered viable for use as both an interim and long-term
measure to reduce mass loading from Cape Fear River Seeps (i.e. Seeps A through D).
These options are also considered suitable as means to reduce mass loading from Willis
Creek Seeps. These options are described in the following sub-sections and the potential
location of these treatment technologies is shown in Figure 4.

Figure 4: Location of Potential Seep Remedies

TR0795 19 November 2019
3.3.1 Interim Remedial Alternative for Seeps: Flow-Through Cells
Interim application at Seeps A through D would involve the installation of V-shaped sheet
pile walls at each seep location to guide seep water discharge through a controlled
structure for on-location treatment. Large wire baskets (gabions), filled with granular
activated carbon (GAC) would be installed in the discharge structures such that the water
discharging from each seep location would flow through the GAC filled gabions. The
PFAS compounds in the seep water would be sorbed by the GAC in the gabions and the
treated water, containing much lower concentrations of PFAS compounds, would flow
out the downhill side of the gabions.
Installation of the seep flow-through structures would commence after the river access
road and all clearing and grubbing is complete. It is assumed that a total of 16 15-foot
lengths of standard steel 22-inch wide sheet pile will be installed at each seep location.
The sheet pile will be driven vertically into the ground to a depth of approximately 11
feet below ground surface (ft bgs) to form a V-shaped sheet pile wall centered on and
oriented perpendicular to the seep discharge channel. The center 2 sheet piles will be
driven an additional approximate 3 feet (ft) to form a window in the middle of the sheet
pile wall such that seep water can flow through the wall. A steel plate approximately 44-
inches wide and 72-inches long will be placed flat side down in the sheet pile window
and welded in place (to the sheet pile) to provide a flat stable surface for the GAC filled
gabions.
Each gabion will be lined with geotextile fabric and filled with new, unused GAC. The
geotextile fabric liner will then be fastened closed and the top of the gabions will be
closed and fastened with steel wire such that the gabions can be moved. Three gabions
will be installed first in the seep A structure as depicted in Figure 5 below using an
excavator and load straps or equivalent. After installation, the gabions will be secured
with sandbags to ensure they stay in place.
If flow-through structures are advanced as an interim measure, the first structure will
likely be constructed at Seep A, and operated for approximately 4-months during which
performance and operational data will be collected to assess system performance.
Lessons learned and performance upgrades developed during this time frame at Seep A
will be incorporated as design modifications for potential application at Seeps B, C, and
D to be installed approximately six months following the Seep A structure installation.

TR0795 20 November 2019

Figure 5: Conceptual Diagram of Seep Flow Through Passive Treatment
Schedule

Bench Scale Testing and Lab Analysis 1
Pilot Study Work Plan 1
NCDEQ Review (1)2
Preliminary Design 1
Geotechnical Drilling and Analysis 2
404/401 Permitting (1)5
Detailed Design 3
Endangered Species Study / Permitting (1)3
Clearing and Grubing 1
Access Road Construction 1
Flow Through Cell Construction at Seep A 2
Seep A Pilot Study 4
Flow Through Cell Construction at Seeps B, C, & D 2
1 - Task timing is dependent upon agency approval timing
Task Duration
(months)Year 1 Year 2

TR0795 21 November 2019
ROM Cost for Seeps A-D
The +50/-30% estimated construction cost for the interim application of flow-through
cells for Seeps A through D is $0.9 to 2 million. The annual O&M cost is estimated to be
$385,000 to $825,000. For simplicity, as interim measures are defined as implementable
within two years, a NPV calculation was not performed. Some or all of the infrastructure
installed during the interim action could be used if this option were converted to a
permanent remedy. The NPV calculation for potential conversion to permanent
installation is presented in Section 3.3.4.
3.3.2 Interim Remedial Action for Seeps: Ex Situ Capture French Drains
This interim remedial measure involves the installation of French drains or equivalent
sumps at each seep location (Seeps A, B, C and D) to capture seep water discharge for
subsequent conveyance to the planned treatment plant to be located at Old Outfall 002
(OOF2). The French drains would consist of permeable trenches excavated across each
seep with perforated piping to collect the water, and sump pumps to pump the captured
seep water to the river access road pipeline for subsequent conveyance to the planned
OOF2 treatment system for treatment and subsequent disposal.
After supporting infrastructure is in place, including roads, power, and conveyance lines,
the seep capture structures will be installed one at a time starting with Seep A and ending
with Seep D. At each seep location, a small catch basin will be excavated upstream from
the planned French drain location. A portable pump with sufficient capacity for total seep
flow will be placed in the basin with the pump discharge hose established to pipe water
from the basin around the planned French drain location for subsequent discharge
downstream from the construction area. Temporarily diverting seep discharge flow
around the construction area will allow for safe and efficient French drain installation.
French drain construction is anticipated to consist of geotextile fabric lining, permeable
backfill (2-inch diameter rocks), and a horizontal perforated pipe at the bottom and a
vertical “sump” pipe at one end. The trench will be approximately 20-ft long and 6 ft deep
with the bottom of the trench sloping to one end. After the piping is installed and the
trench is backfilled, it will be armored at the ground surface with an additional layer of
geotextile and concrete paver blocks to prevent erosion during storm events. A conceptual
diagram is shown below in Figure 6.
After the French drain installation a submersible pump will be installed in the vertical
sump, wired to provide power, connected to the previously installed piping and function
tested to ensure proper operation. The temporary seep water diversion pump and
discharge hose will be removed, and the seep collection system will be put in operation.

TR0795 22 November 2019

Figure 6: Conceptual Diagram of Seep French Drain Ex Situ Capture
Schedule

Bench Scale Testing and Lab Analysis 2
Preliminary Design 2
Endangered Species & Wetland Study 3
Geotechnical Drilling and Analysis 2
404/401 Permitting1 5
Detailed Design 4
Bidding and Award 3
New Electrical Service 5
Clearing and Grubing (assumes ES restriction)2
Collection System Construction 4
Treatment System Construction & startup testing 4
System Startup 1
1 - Task timing is dependent upon agency approval timing
Task Duration
(months)Year 1 Year 2 Year 3

TR0795 23 November 2019
ROM Cost for French Drains
The +50/-30% estimated construction cost for the interim application of French drains to
capture Seeps A through D is $9.5 to 20 million. The annual O&M cost is estimated to
be $410,000 to $890,000. For simplicity, as interim measures are defined as
implementable within two years, a NPV calculation was not performed. The NPV
calculation for potential conversion to permanent installation is presented in Section
3.3.5. Much of the infrastructure installed during the interim action could be used if this
option were converted to a permanent remedy.
3.3.3 Interim Remedial Action for Seeps: PlumeStop™
PlumeStop™ is an innovative groundwater remediation technology designed to sequester
groundwater contaminants via sorption. It is composed of very fine particles (1 to 2
micrometers [µm]) of activated carbon suspended in water. The material is held in
suspension using proprietary organic polymers that allow easy injection and dispersion
into the subsurface. As the polymer breaks down, the carbon coats the solid material in
the aquifer matrix creating a passive, subsurface carbon adsorption filter. PlumeStop™
has been successfully applied to remediate various contaminants including site specific
PFAS.
As an interim measure, PlumeStop™ barriers would be installed in the perched zone
immediately upgradient of Seeps A and B (Figure 7). Based on the currently available
geologic data, the Seep A barrier would be 900 ft long with a treatment zone from 8 to
18 ft bgs and the Seep B barrier would be 1,800 ft long with a treatment zone from 12 to
15 ft below grade. Prior to placing each barrier, a detailed investigation would be
performed to refine the design parameters for each wall and install monitoring wells for
performance monitoring. Two design life options were considered (5 years and 10 years).
The barrier would be designed to retard the flow of site specific PFAS for a minimum of
5 or 10 years depending on the size of the barrier and amount of plume stop injected. At
the end of the design life additional product could be injected to extend the life of the
barrier. However, for this analysis it was assumed that a permanent remedy would be in
place and no additional material would be injected.
A limitation of the PlumeStop™ approach is that the PFAS mass is not removed from the
subsurface but is effectively transferred to a solid phase. This mechanism is effective until
the solid is saturated and then requires additional applications or the solid media can
become a source on its own. Long term studies have not been completed so it is not
known if the upgradient groundwater no longer has PFAS if the PFAS sorbed to the
material would then begin to release PFAS due to equilibrium forces.

TR0795 24 November 2019

Figure 7: Location of potential interim PlumeStop™ applications for groundwater seeps originating from Perched Zone groundwater flow.

Schedule

Pilot Study Work Plan 1
NCDEQ Review1 1
Pre-design data collection and well Installation 2
Lab Analysis 2
Injection and Mix Design 2
Injection Permit Application/Review/Issuance2 1
PlumeStop Injection 1
Performance Monitoring 60
1 - Task timing is dependent upon agency approval timing
2 - Task timing is dependent upon permitting process and assumes multiple permits
Year 5TaskDuration
(months)Year 1 Year 2 Year 3 Year 4

TR0795 25 November 2019

Conceptual Cost for PlumeStop™
The +50/-30% estimated construction cost for the interim application of PlumeStopTM at
Seeps A and B is $9 to 19 million. The annual O&M cost is estimated to be $91,000 to
$195,000.
3.3.4 Permanent Remedial Alternative for Seeps: Flow-Through Cells
Assuming testing and analysis of the IM performance confirms this is a viable long-term
remedy, then a permanent design of flow-through cells would be completed (similar to
Section 3.3.1). Improvements based on lessons learned from early implementation and
ongoing maintenance and replacement of GAC would be incorporated.
ROM Cost for Seeps A-D
The +50/-30% estimated NPV of 20 years of flow-through cells at Seeps A through D is
$7 to 15 million. This includes the construction costs already discussed in Section 3.3.1.
ROM Cost for Willis Creek Seeps
The +50/-30% estimated construction cost for the permanent application of flow-through
cells for Willis Creek Seeps is $35,000 to 75,000. The annual O&M cost is estimated to
be $63,000 to 135,000. The 20-year NPV is estimated to be from $1.4 to 3.0 million.
3.3.5 Permanent Remedial Alternative for Seeps: Ex Situ Capture French Drains
Assuming testing and analysis of the IM performance, if applied, shows it to be a viable
long-term remedy, the permanent application of French drains would be similar to those
described in Section 3.3.2, with improvements made to the structures based on lessons
learned from early implementation, and ongoing maintenance.
The +50/-30% estimated NPV of 20 years of French drains at Seeps A through D is $15
to 33 million. This includes the construction costs already discussed in Section 3.3.2.
3.3.6 Permanent Remedial Alternative for Seeps: PlumeStop™
In this alternative, as a permanent measure, three PlumeStop™ barriers would be installed
upgradient of the four Willis Creek seeps. Based on the available geologic data, the
barriers would be 700, 1,200, and 700 feet long for seeps WC-1-TR-2, WC-3-TR-2, WC-
3-TR-3-, and WC-4-TR-1, respectively. The barrier would be designed to retard the flow
of site specific PFAS for a minimum of 20 years. At the end of the design life additional
product could be injected to extend the life of the barrier.

TR0795 26 November 2019
Schedule

The +50/-30% estimated construction cost for the permanent application of PlumeStop™
at the Willis Creek seeps is $34 to 73 million. The annual O&M cost is estimated to be
$91,000 to 195,000. The 20-year NPV is estimated to be $36 to 77 million. The cost at
this location is controlled by the higher gradient and hydraulic conductivity in the surficial
zone as well as the desired longer life of the barrier.
3.4 Pathway: Onsite Black Creek Aquifer Groundwater
In addition to the seven projects outlined in the Reduction Plan, Chemours also proposes
to act on an expedited basis to address surface water loadings from onsite groundwater,
other than the seeps. The potential interim and permanent remedies described in the
following sections are highly conceptual due to the lack of sufficient design inputs that
would be derived from scenarios programmed in the numerical groundwater model,
which is currently in final stages of development. This model will be utilized to further
evaluate these concepts and present the findings in or in conjunction with the CAP.
3.4.1 Interim Alternatives Groundwater Extraction from Existing Monitoring Wells
This interim remedial alternative consists of installing submersible electric pumps in
seven existing black creek monitoring wells and pumping the water to the OOF2
treatment plant for treatment and discharge. Submersible electric pumps would be
installed in seven site wells: BCA-01, BCA-02, PW-9D, PW-10DR, PW-11, PW-14, and
PW-15R (Figure 8). Piping would be installed to convey the water to the proposed OOF2
treatment plant, potentially above-grade as a time-saving measure. Based on available
Work Plan Preparation 1
NCDEQ Review1 1
Pre-design Data Collection 4
Injection and Mix Design 2
Injection Permitting2 3
PlumeStop Inections 1
Performance Monitoring 60
1 - Task timing is dependent upon agency approval timing
2 - Task timing is dependent upon permitting process
Year 5TaskDuration
(months)Year 1 Year 2 Year 3 Year 4

TR0795 27 November 2019
information, it is anticipated that a sustained flow rate of 2 gpm from each well could be
achieved. Therefore, the total flow would be 14 gpm. It is assumed that there will be
sufficient excess capacity at the OOF2 treatment plant and that the discharge could be
covered under the current National Pollutant Discharge Elimination System (NPDES)
permit application for that plant without additional modification.
Figure 8: Potential Black Creek Monitoring Wells for Interim Action of Extraction and
Treatment

TR0795 28 November 2019
Schedule
The OOF2 treatment system is required to be constructed and operational by September
30, 2020, assuming permits are issued in a timely manner. The installation of pumps in
existing wells could be incorporated into the overall OOF2 treatment system construction
in this timeframe as well.
The schedule table below represents the interim scenario for groundwater extraction from
existing monitoring wells.

ROM Cost for Groundwater Extraction from Existing Monitoring Wells
Costs were estimated and considered to be accurate within the +50/-30 % range. The
construction costs range from $560,000 to 1.2 million, annual O&M costs are $48,000 to
102,000. For simplicity, as interim measures are defined as implementable within two
years, a NPV calculation was not performed.
3.4.2 Interim Alternative Groundwater Extraction from Additional Extraction Wells
This interim alternative measure would enhance the interim remedy discussed in the
previous section with the installation of seven additional wells (6” diameter extraction
wells as opposed to the existing 2” monitoring wells). The wells would be installed along
the same alignment as shown in Figure 8, in coverage gaps between the existing wells,
with some efficiency in sharing a path to the OOF2 treatment plant. The depth of well
installation would be on average 140 ft bgs to extract from the Black Creek aquifer in this
area of the Site.
It is assumed that the additional wells would extract 10 gpm each (70 gpm total), and that
there will be sufficient excess capacity at the OOF2 treatment plant and that the discharge
could be covered under the current NPDES permit application for that plant without
modification. Additional groundwater modeling is required to refine this approach.

Detailed Design 2
Contracting 1
Site Work Installation 6
Task Duration
(months)Year 1

TR0795 29 November 2019
Schedule
The OOF2 treatment system is required to be constructed and operational by September
30, 2020, assuming permits are issued in a timely manner. The installation of new wells
and incorporating this additional flow could be achieved approximately within a similar
timeframe.
The schedule table below represents the interim scenario for groundwater extraction from
additional extraction wells.

ROM Cost for Groundwater Extraction from Additional Extraction Wells
Costs were estimated and considered to be accurate within the +50/-30 % range. The
construction costs range from $0.7 to 1.5 million, annual O&M costs are $105,000 to
225,000. For simplicity, as interim measures are defined as implementable within two
years, a NPV calculation was not performed.
3.4.3 Permanent Remedies for Onsite Groundwater: Extraction with Vertical
Extraction Wells
This alternative would mitigate the flux of onsite groundwater into the Cape Fear River
via hydraulic containment of groundwater. Groundwater could be extracted from a series
of vertical wells or horizontal wells. For the purpose of this analysis, vertical wells were
assumed; however, the final design would utilize the most efficient option. Following
extraction, the water would be pumped to a new standalone treatment system, and then
discharged to the river. This remedial alternative would not include a barrier between the
extraction wells and the river (e.g., a steel sheet pile wall), thus the wells would be
installed along an alignment sufficiently set back from the river to avoid drawing in river
water to the Site. This alignment would need to be developed with the numerical model
in a full design.
Pre-Design Investigation 3
Detailed Design 6
Potential mod. of NPDES Permit for OOF2 (1)6
Contracting 1
Drilling 1
Site Work Installation 6
1 - Dependent upon agency approval.
Task Duration
(months)Year 1 Year 2

TR0795 30 November 2019
A conceptual layout is provided in Figure 9 which shows the 8,500 LF alignment of
extraction wells. Based on drawdown requirements using analytical methods and
assuming vertical extraction wells as a simplifying assumption, it was estimated that the
wells would be installed at a spacing of 50 ft, and each would extract on average 30 gpm.
This would require 170 extraction wells and a total flow rate of 5,100 gpm (7.3 MGD). It
was assumed that extraction wells would be installed to an average depth of 100 ft bgs to
reach the Black Creek aquifer.
It was assumed that the well pumps would feed into a common high-density polyethylene
(HDPE) force main for distribution to a new treatment system constructed onsite. Pipe
sizing would range from 2 to 24 inches in diameter, depending on the estimated head loss,
which is a factor of flow rate and distance from the system. It is anticipated that with the
availability of submersible well pumps to provide sufficient hydraulic head, no lift
stations would be required.
The design basis for treatment of the extracted groundwater includes feed-forward
pumps, a chemical precipitation system, multimedia filtration (MMF) skids, GAC skids,
backwash supply and waste tanks, and a solids processing treatment train for chemical
precipitation of solids. Major process equipment is assumed to be installed within pre-
engineered buildings. It is assumed that the influent median Perfluoromethoxypropyl
carboxylic acid (PMPA) and perfluoro-1-methoxyacetic acid (PFMOAA) concentrations
would be 8,200 and 150,000 nanogram per liter (ng/L), respectively. It is assumed that
PFMOAA is the driving influent COC for GAC utilization, and that 99% removal is
required.
Discharge would require regulatory approval via NPDES permits, and construction of
outfalls in the vicinity of the river would likely require regulatory approval from the
United States Army Corps of Engineers (USACE).

TR0795 31 November 2019

Figure 9: Conceptual Layout of Onsite Groundwater Extraction Remedy
Schedule

Numerical Modeling 1
Pre-Design Investigations 6
Detailed Design and Permitting (1)12
Permits/ Agency Approvals (2)12
Contracting 3
Drilling and Aquifer Pump Testing 6
Trenching and Piping Installation 24
System Installation 24
Testing and Commissioning 12
1- Permits include but may not be limited to 404/401 and NPDES
2 - Task timing is dependent upon agency approval timing
Task Duration
(months)Year 1 Year 2 Year 3 Year 4 Year 5

TR0795 32 November 2019
Cost
As discussed in the introduction to Section 3, the numerical model is necessary to
generate the design inputs that are needed to develop reliable cost estimates for long-term
groundwater remedies. The scenario described in this section is one of several that will
be evaluated with the numerical model in the following months.
3.4.4 Permanent Groundwater Remedy: Barrier Wall and Groundwater Capture
This alternative would mitigate the flux of onsite groundwater into the Cape Fear River
via the installation of steel sheet piles coupled with hydraulic containment of groundwater
to keep groundwater from overtopping the sheet pile. The sheet pile would primarily serve
to cut off the interface between groundwater and river water, preventing the undesired
extraction of river water. A conceptual layout is provided in Figure 10, which shows the
8,500 linear ft of sheet piling. The installation depth was estimated to be 50 ft bgs in order
to key into the Upper Cape Fear confining unit.
Groundwater could be extracted from a series of vertical wells or horizontal wells. For
the purpose of this analysis, vertical wells were assumed; however, the final design would
utilize the most efficient option. Following extraction, the water would be pumped to a
treatment system, and then discharged to the river.
It is assumed that extraction well spacing behind the steel wall would be 200 ft, and that
each well on average would yield 30 gpm. Drawdown requirements are less significant
than the remedy discussed in the previous section, as the pumping is primarily required
to prevent mounding behind the steel wall. This would result in approximately 1,275 gpm
(1.8 MGD) of extracted groundwater.
Conceptual design of the hydraulic piping (head loss, etc.) and the treatment system
(MMF and GAC skids, etc.) is similar in nature to that described in Section 3.4.3. It is
assumed that the influent median PMPA and PFMOAA concentrations would be 8,200
and 150,000 ng/L, respectively. It is assumed that PFMOAA is the driving influent COC
for GAC utilization, and that 99% removal is required.

TR0795 33 November 2019

Figure 10: Conceptual Layout of Onsite Groundwater Extraction Remedy Behind Barrier
Wall
Schedule

Numerical Modeling of Permanent Onsite GW Remedy 1
Pre-Design Investigations 6
Detailed Design and Permitting (1)12
Permits/ Agency Approvals (2)12
Contracting 3
Drilling and Aquifer Pump Testing 6
Sheet Pile Installation 20
Trenching and Piping Installation 24
System Installation 24
Testing and Commissioning 12
1- Permits include but may not be limited to 404/401 and NPDES
2 - Task timing is dependent upon agency approval timing
Year 5Year 4TaskDuration
(months)Year 1 Year 2 Year 3

TR0795 34 November 2019
Cost
As discussion in the introduction to Section 3, the numerical model is necessary to
generate the design inputs that are needed to develop reliable cost estimates for long-term
groundwater remedies. The scenario described in this section is one of several that will
be evaluated with the numerical model in the next two months.
3.5 Pathway: Outfall 002
In addition to process water diversion and air abatement actions already in place, several
other potential control approaches were evaluated to achieve even further reductions of
PFAS reaching the Cape Fear River via Outfall 002. These options were outlined the
Outfall 002 Assessment Report (Geosyntec 2019e) and the following options are further
evaluated in this Supplemental Report:
• Remove targeted sediments, which could contain PFAS from historical aerial
deposition, along the open section of the Cooling Water Channel and in the Open Channel to Outfall 002 (Section 3.5.1);
• Develop and implement an Industrial Stormwater Pollution Prevention Plan
(SWPPP) to reduce the potential for stormwater contamination from industrial
activities and other sources such as impacted soils or active construction (Section 3.5.2).
• Implement targeted stormwater source control and/or treatment, including
covering/sealing of certain areas, replacement of materials, sweeping or
washing/rinsing, or targeted collection and treatment (Section 3.5.3)
• Decommissioning of the terracotta pipe to the WWTP to prevent transport of PFAS that are potentially still present in the pipe or adhered to remnant sediments (Section 3.5.4).
• Assess the potential for groundwater intrusion of perched zone groundwater containing HFPO-DA infiltrating into the Open Channel to Outfall 002 (Section 3.5.5).
• Treat stormwater end of pipe, up to a given design flowrate, by constructing a
separate collection system for either stormwater or NCCW to segregate these flows and provide treatment of the stormwater (Section 3.5.6).
• Diversion and treatment of all flows (i.e., stormwater and dry weather flows) end
of pipe (at Outfall 002) using carbon filtration, up to a given design flowrate
(Section 3.5.7).
These approaches provide differing levels of potential reductions, time to implement, and
cost effectiveness for benefit achieved. The following sections provide more details on
each proposed option.

TR0795 35 November 2019
3.5.1 Conveyance Network Sediment Removal
Chemours completed sediment removal in a section of the conveyance network in
October 2019 (Figure 11). Sediment removal may become a maintenance activity and as
such this alternative is outlined in this Supplemental Report.
This alternative would remove sediment that has accumulated in the Non-contact Cooling
Water Channel of the IXM Monomers area, and the Open Channel to Outfall 002 (see
proposed action 3 in the Reduction Plan [Geosyntec, 2019a] and section 4.2 of the Outfall
002 Assessment [Geosyntec, 2019e]). It is estimated that approximately 150 tons of
sediment are within the 2,800 ft of the IXM Monomers Area, and 320 tons of sediment
are within the Open Channel to Outfall 002. The sediment would be removed with a
combination of vacuum trucks and long-reach excavators and deposited onsite until waste
profiling is complete. For the purposes of this evaluation, it is assumed that the material
would be sent to Waste Management’s facility in Emelle, Alabama for disposal. Disposal
rates were obtained from Chemours facility staff based on recent work.

Figure 11: Sediment removal from Open Channel on October 15, 2019
3.5.2 Stormwater Pollution Prevention Plan
As described in the Reduction Plan (Geosyntec, 2019a) and the Outfall 002 Assessment
(Geosyntec, 2019e), PFAS from historical aerial deposition may be present in onsite soils
and could potentially be transported to Outfall 002 through the Site Conveyance Network.

TR0795 36 November 2019
Chemours will fund a third party to prepare an industrial Stormwater Pollution Prevention
Plan (SWPPP) and train Facility personnel on implementation of the SWPPP.
The SWPPP will include information such as roles and responsibilities of staff involved
with stormwater management, location of industrial materials stored and transported at
the site (indicating materials potentially exposed to precipitation), industrial activities in
each area of the site, pollutants of concern related to exposed industrial activities, existing
and planned best management practices (BMPs), and site drainage maps. The SWPPP
will provide facility-specific guidance on stormwater BMPs, such as good housekeeping
practices, exposure minimization, and erosion controls intended to reduce the potential
for stormwater contamination from industrial activities and known sources (i.e., impacted
soils, active construction, soil stockpiling).
Based on the single stormwater sampling event, conducted in June 2019, PFAS
concentrations were not elevated near construction areas or soil stockpiles and data did
not indicate any relationship between PFAS and total suspended solids (TSS). Therefore,
this action is not expected to yield significant reduction of stormwater loads to the river,
and no reduction quantification was possible at this time.
However, it may be possible that reducing soil erosion in wet weather will reduce
sediment accumulation along the Site Conveyance Network (and PFAS were detected in
sediment within the Cooling Water Channel), which could then reduce sediment
contribution to overlying water during dry weather. Potential erosion control measures
include silt fencing, hydroseeding, soil binders, fiber rolls, sandbags, or straw bales. An
example of fiber rolls is shown in Figure 12.

TR0795 37 November 2019

Figure 12. Example Erosion Control Measure (fiber rolls)
Schedule
A SWPPP will be developed by April 30, 2020. Upon completion of the SWPPP,
Chemours will provide an implementation schedule for action items identified in the
SWPPP . The target timeline for SWPPP implementation will be six months to one year
from completion of SWPPP development. In order to accelerate preparation and
implementation of the SWPPP Chemours plant staff and the contractor preparing the
SWPPP are having an in-person kick off meeting on November 12, 2019.
Conceptual Cost for Development and Implementation of SWPPP
Development of the SWPPP and training for Facility personnel will cost approximately
$30,000. Training for new Facility personnel will be conducted on an as-needed basis.
The costs to implement the SWPPP are uncertain until the SWPPP is developed, but
implementation costs are estimated to be less than $0.5 million.
3.5.3 Targeted Stormwater Control
3.5.3.1 Stormwater Action Plan
As described in proposed action 5 of the Reduction Plan (Geosyntec, 2019a) and section
4.6 of the Outfall 002 Assessment (Geosyntec, 2019e), results from the stormwater
sampling event in June 2019 indicated areas of elevated PFAS concentrations in

TR0795 38 November 2019
stormwater. This suggests that some combination of targeted source control and
stormwater collection and treatment could achieve mass loading reductions. Since only
one data set exists at present, additional data and assessment activities are necessary to
develop a better understanding of stormwater levels and spatial patterns throughout the
Site in order to select and design suitable approaches.
Chemours will fund third party contractors to conduct two additional stormwater grab
sampling programs to evaluate stormwater concentrations. Chemours will also fund a
third-party contractor to develop a hydrologic stormwater model (calibrated using onsite
flow measurements) and a targeted stormwater action plan and best management
practices, based on the data from the stormwater grab sampling events and the outcome
of modeling analyses. The stormwater action plan will outline initial actions to be
performed, and future performance evaluation reporting of the actions will include any
potentially recommended supplementary actions.
The challenge associated with development of the stormwater action plan is the need for
additional data and the uncertainty in the level of additional data that may be necessary.
Chemours continues to collect data to assess PFAS compounds in stormwater, including
the additional stormwater grab sampling and hydrologic model development. However,
further data collection related to PFAS in stormwater may be needed during development
of the stormwater action plan.
Schedule
The approximate timeline for development of a stormwater action plan is one year. The
schedule for implementation of actions identified in the stormwater action plan will be
provided after the plan is developed. To accelerate schedule of developing the action plan
Chemours has already collected a second round of stormwater data and is planning one
more round of sample collection. Additional Chemours plant staff and the contractor
preparing the action plan are holding a kick off meeting on November 12, 2019.
Cost
Development of a stormwater action plan, including conducting two additional
stormwater sampling events and developing and calibrating a hydrologic model, will cost
between $100,000 and 200,000. Costs associated with implementation of the plan are
unknown until the plan is developed.

TR0795 39 November 2019
3.5.3.2 Example Targeted Stormwater Treatment
Based on results from the June 2019 stormwater sampling event, areas of high PFAS
concentrations in stormwater were observed spatially within the Site. The Chemours
Monomers IXM area, in the northeast portion of the Site, was one of the areas observed
to have elevated stormwater concentrations. Because these observations were based on a
single stormwater sampling event, further sampling is currently planned to provide
additional evidence for these observations.
However, for planning purposes, targeted treatment of stormwater in this area was further
investigated at a conceptual level. There are multiple options that could potentially be
considered for treatment of stormwater in targeted areas. Development of the stormwater
action plan (described above) will provide additional information on potential
effectiveness of treating onsite stormwater through different measures.
Currently, before additional options have been investigated during development of the
stormwater action plan, two potential treatment options include flow-through cells and
ex-situ treatment. Flow through cells would be similar to Alternative A for treatment of
groundwater seeps (described in Section 3.3), where stormwater would be directed
through a controlled structure filled with GAC for on-location treatment.
Ex-situ treatment of stormwater in the Chemours Monomers IXM area could consist of
carbon filtration, new stormwater collection systems (e.g., drain inlets or catch basins and
piping), pump stations, local storage and pretreatment, and piping to discharge treated
flows back into the Site Conveyance Network. The general concept for this targeted
stormwater treatment is shown in Figure 13.

TR0795 40 November 2019

Figure 13. Targeted Stormwater Treatment Design Concept
A hydrologic model was used to model flowrates from the drainage area using historical
hourly rainfall data from 2006 to 2018. This concept assumes that 13.9 acres in the
Chemours Monomers IXM area drains to the BMP, the average imperviousness of the
drainage area is 59%, and the underlying soils within the drainage areas consist of
hydrologic soil group A (but soil was assumed to be compacted). Various storage
volumes, representing a storage tank that would capture stormwater and slowly release
the captured volume to the treatment system (with an assumed 24-hour drawdown time),
were also modeled and the long-term percent capture of stormwater from the drainage
area was determined for each storage volume. The range of storage volume sizes were
then plotted against the long-term percent capture of runoff volume to determine a cost-
effective design, where increasing the BMP size would add significant cost but very little
increase in runoff volume captured. The average annual percent capture of runoff volume,
from the 13.9-acre drainage area, for the selected BMP size was 81%. This expected
capture of stormwater from the specified drainage area would result in an estimated
reduction of HFPO-DA loading to the river of 1%, compared to loading to the river in
2018.
The design basis for ex-situ targeted treatment of stormwater in the Chemours Monomers
IXM area includes a stormwater lift station, influent equalization (EQ) tank, feed-forward
pumps, MMF skids, GAC adsorption skids, chemical precipitation system to remove
solids collected via the GAC and MMF backwash cycles (including flash and flocculant

TR0795 41 November 2019
mixing tanks, inclined plate clarifier [IPC], chemical storage and metering tanks,
backwash tank), and solids processing train for chemical precipitation solids (including
solids transfer pumps, solids thickening tank, thickened solids pump, and plate-and-frame
filter press). Details of the treatment process are shown in Figure 14.
The storage tank needed for this treatment scenario is expected to be approximately
220,000 gallons and the treatment flowrate is 150 gallons per minute. Approximately 8
million gallons of stormwater is expected to be treated annually (based on the modeling
performed using rainfall data from 2006 through 2018).

Figure 14. Targeted Stormwater Treatment
Schedule
The schedule for treatment of targeted stormwater using flow-through cells would be
similar to the schedule outlined for the permanent remedial alternative for groundwater
seeps via flow-through cells (shown in Section 3.3).
The schedule for implementation of a potential ex-situ treatment BMP in a high priority
stormwater area will exceed two years. Implementation of targeted stormwater treatment
BMPs may require up to four years. Following completion of additional sampling and
development of the stormwater action plan, the interim tasks and approximate durations
for this potential control approach include the tasks shown below.

TR0795 42 November 2019

ROM Cost
As discussion in the introduction to Section 3, the scope of stormwater treatment and
technology assessment are required to develop a reliable cost estimate for this remedy,
which is being advanced.
3.5.4 Terracotta Pipe Decommissioning
The Terracotta pipe was designed to convey wastewaters from the various manufacturing
areas on the Site to the wastewater treatment plant (WWTP). The pipe originated in the
Chemours Monomers IXM Area and included inputs from Monomers IXM, Kuraray
SentryGlas®, Kuraray Trosifol®, the Kuraray Laboratory, and wastewater from
demineralized water production. Figure 15 shows the terracotta piping network. In 2017,
Chemours diverted all Monomers IXM process wastewater flows from the WWTP and
began sending them offsite for disposal. In 2019, the east-west section of the terracotta
pipe (hatched piping line in Figure 15) that originates in Monomers IXM was grouted to
mitigate the potential for PFAS originating from the terracotta pipe to be released to the
Cape Fear River (Geosyntec, 2019f). The Kuraray areas and the Site demineralized water
production operations actively transmit water to the WWTP via the terracotta pipe.
None of the current inputs to the terracotta pipe use or produce PFAS, and there have
been no known contributions of process water from the Monomers IXM Area to the
WWTP by the terracotta pipe since November 2017. However, to further mitigate the
potential for PFAS to reach the Cape Fear River via the WWTP, the remaining ungrouted
sections of the terracotta pipe will be fully decommissioned and grouted no later than
Stormwater Action Plan 12
Planning and Feasibility 6
Preliminary Design (1)6
Permitting Plan 2
Final Design 12
Permits/Approvals (2)12
Contracting 3
Construction 18
Startup Testing 2
1- Includes hydrologic/hydraulic calculations, topographic survey, geotechnical investigations
2 - Task timing is dependent upon agency approval timing
Task Duration
(months)Year 1 Year 2 Year 3 Year 4

TR0795 43 November 2019
December 2021. Once this is completed the current flow through the terracotta pipe to
the WWTP will be transmitted through new aboveground piping.
Schedule
This work will be completed by Kuraray and Chemours by fall 2021. Presently Kuraray
is reviewing potential designs to advance the project to the detailed design phase.
ROM Cost
The cost for grouting the east-west portion of the terracotta pipe in 2018 was
approximately $100,000. The remaining portions of the terracotta pipe that are still in
use are expected to also cost approximately $100,000. Kuraray will be responsible for
procurement and installation of the new aboveground piping and, as such, Chemours does
not have costing information for this component.

Figure 15: Terracotta Piping Layout
Notes: Hatched lines were decommissioned in 2018 all remaining will be replaced with
above ground piping in 2021.

TR0795 44 November 2019
3.5.5 Mitigation of Groundwater Intrusion into Outfall 002
As described in proposed action 7 of the Reduction Plan (Geosyntec, 2019a) and section
4.3 of the Outfall 002 Assessment (Geosyntec, 2019e), it is possible that perched zone
groundwater is entering the Open Channel to Outfall 002 near the DuPont area, and
contributing to PFAS loading. This scenario is still under evaluation, but for the purposes
of this response, it is assumed that groundwater is entering the open channel, and that
active mitigation would be performed.
To mitigate this intrusion, it is assumed that the infiltration of DuPont non-contact cooling
water (NCCW) into the perimeter unlined ditches is a significant contributor to the
perched zone groundwater head, and that routing this NCCW directly to Outfall 002 will
reduce the perched zone levels to the point that groundwater intrusion is eliminated. For
cost purposes, it was assumed that up to eight discharges from the DuPont area would be
connected to new process piping and conveyed in a common trench about 500 linear ft to
the Open Channel.
Schedule
The timeframe required to implement the piping redirection would be one year, after
which point additional data collection, analysis and evaluation would be required to
assess the potential impact on groundwater intrusion. If insufficient, additional measures
could be required, such as groundwater extraction under the DuPont area. Accordingly,
it is conservatively estimated that the full implementation of this alternative would take
approximately three to five years. To accelerate assessment and implementation of this
action Chemours surveyed the bottom of the open channel to Outfall 002 during the
October 2019 plant shutdown when there was limited water present in the Outfall (see
Figure 16).

Detailed Design 3
Contracting 1
Implementation 6
Effectiveness Evaluation 12
Contingent Action 12-36
Task Duration
(months)Year 1 Year 2 Year 3 Year 4 Year 5

TR0795 45 November 2019
Conceptual Cost
Costs were estimated and considered to be accurate within the +50/-30 % range. The
construction costs range from $490,000 to 1,050,000. No annual costs would be required.

Figure 16: Surveyed elevations of the bottom of the Open Channel to Outfall 002
3.5.6 Treatment of all Stormwater at Outfall 002
As described in section 4.7 of the Outfall 002 Assessment (Geosyntec, 2019e), a potential
control approach for addressing PFAS from Outfall 002 involves treating stormwater
flows “end of pipe” (i.e., at Outfall 002), up to a given design flowrate. This approach
involves constructing a separate collection system for either stormwater or NCCW to
achieve segregation of these flows, since dry weather flows and stormwater are currently
conveyed to Outfall 002 via a combined network. Collection system separation and
treatment of stormwater from the entire Site would require significant cost and time to
plan, design, permit and construct, and significant cost to operate and maintain given the
expected required pace of carbon replacement or regeneration.
Similar to the potential control approach of targeted stormwater control through capture
of stormwater flows in high priority stormwater areas and treatment using carbon
filtration, the potential control approach to treat all stormwater flows was modeled using
a hydrologic model of the Site. The area within the Site that drains to Outfall 002 was
modeled using the long-term simulation of historical rainfall from 2006 through 2018.
This concept assumes that 230 acres drain to Outfall 002 (modeled as 50 catchments), the

TR0795 46 November 2019
average imperviousness of the entire drainage area is 35%, and the majority of underlying
soils within the drainage areas consist of hydrologic soil group A (but soil was assumed
to be compacted).
A range of storage volume sizes was also modeled, and the cost-effective storage size
was determined based on the plot of storage volume (i.e., BMP size) versus percent
capture of runoff volume. Increasing the BMP size greater than the selected storage
volume would add significant cost but would only result in minimal increases in the
amount of runoff volume captured and treated. The average annual % capture of runoff
volume, from the entire Site draining to Outfall 002, for the selected BMP size was 85%.
This expected capture of Site stormwater would result in an estimated reduction of HFPO-
DA loading to the river of 2% (compared to loading to the river in 2018).
The design basis for treatment of all Site stormwater includes rerouting NCCW to a new
piping system (such that stormwater is still conveyed in the Site Conveyance Network),
a stormwater lift station, influent EQ tank, feed-forward pumps, MMF skids, GAC
adsorption skids, chemical precipitation system to remove solids collected via the GAC
and MMF backwash cycles (including flash and flocculant mixing tanks, IPC, and
chemical storage tanks and metering pumps), and solids processing train for chemical
precipitation solids (including solids transfer pumps, solids thickening tank, thickened
solids pump, and plate-and-frame filter press). Details of the conceptual treatment system
are shown in Figure 17.
The required storage volume and treatment flowrate for this scenario would be very large.
The storage tank for this scenario is expected to be approximately 5.5 million gallons and
the treatment flowrate is approximately 3,800 gallons per minute. Approximately 120
million gallons of stormwater is expected to be treated annually (based on the modeling
performed using rainfall data from 2006 through 2018).

TR0795 47 November 2019

Figure 17. All Site Stormwater Treatment

Schedule
Implementation of this potential control approach would be expected to take up to five
years.

ROM Cost
Costs were estimated and considered to be accurate within the +50/-30 % range. The cost
estimate for treatment of all stormwater end of pipe (up to a certain flowrate) includes
construction costs that range from $50 to 108 million, annual O&M costs for 20 years
from $1.3 to 2.7 million, and an NPV ranging from $68 to 146 million.
Planning and Feasibility 6
Preliminary Design 6
Permitting Plan 2
Final Design 12
Permits/Approvals (1)12
Contracting 3
Construction (2)18
Startup Testing 2
1- Dependent upon agency approval timing.
2 - Includes construction of treatment system and new site conveyance network.
Task Duration
(months)Year 1 Year 2 Year 3 Year 4 Year 5

TR0795 48 November 2019

3.5.7 Treatment of all Flows at Outfall 002
As described in section 4.9 of the Outfall 002 Assessment (Geosyntec, 2019e), a potential
control approach for addressing PFAS from Outfall 002 involves treating all flows (i.e.,
stormwater and dry weather flows) end of pipe (at Outfall 002), up to a given design
flowrate. This option would not require separation of the current collection system;
therefore, the existing Site Conveyance Network could remain. This would require a new
diversion structure above Outfall 002, a new pump station, a new storage tank, and a new
treatment system similar to that described in the Treatment of all Stormwater control
approach (discussed in Section 3.5.6). Treated flows would be discharged back into the
Open Channel above Outfall 002.
This control approach was conceptually designed to achieve an 80% reduction in HFPO-
DA loading at Outfall 002, as compared to 2018. This involves determining a treatment
flowrate that achieves 100% dry weather flow capture and significant stormwater flow
capture (73% of stormwater flow, in the 2018 calendar year). The required treatment
flowrate for this scenario is approximately 21.1 million gallons per day (14,600 gallons
per minute) and the total annual treated volume of water is approximately 7,700 million
gallons per year (based on the modeling performed using rainfall data from 2006 through
2018). This potential control approach would result in an estimated reduction of HFPO-
DA loading to the river of 3% (compared to loading to the river in 2018).
The design basis for treatment of all Outfall 002 flows includes influent wetwell for
stormwater and process wastewater collection, feed-forward pumps, MMF skids, GAC
adsorption skids, chemical precipitation system to remove solids collected via the GAC
and MMF backwash cycles (including flash and flocculant mixing tanks, IPC, chemical
storage tanks and metering pumps), and solids processing train for chemical precipitation
solids (including solids transfer pumps, solids thickening tank, thickened solids pump,
and plate-and-frame filter press). Details of the conceptual treatment system are shown
in Figure 18.

TR0795 49 November 2019

Figure 18. All Outfall 002 Treatment
Schedule
Implementation of this potential control approach would be expected to take up to
between three to five years.

ROM Cost
Costs were estimated and considered to be accurate within the +50/-30 % range. The cost estimate for treatment of all flows at Outfall 002 (up to a specified flowrate) includes
construction costs ranging from $59 to 127 million, annual O&M costs for 20 years of
$4.1 to 8.7 million, and a NPV ranging from $118 to 252 million.
Planning and Feasibility 6
Preliminary Design 6
Permitting Plan 2
Final Design 12
Permits/Approvals (1)12
Contracting 3
Construction (2)18
Startup Testing 2
1- Dependent upon agency approval timing.
2 - Includes construction of treatment system and new site conveyance network.
Task Duration
(months)Year 1 Year 2 Year 3 Year 4 Year 5

TR0795 50 November 2019
3.6 Pathway: All Loadings From Willis Creek and Georgia Branch Creek
The flow and estimated PFAS loading to Willis Creek and Georgia Branch Creek have
been previously estimated (Geosyntec 2019c). These creeks are tributaries to the Cape
Fear River. Two remedial alternatives were considered as outlined below.
3.6.1 Capture and Treatment at Mouths of Creeks
This option would require the installation of dams at the mouths of both Willis and
Georgia Branch Creeks (estimated to be 2,917 and 2,440 gpm, respectively), and
pumping and treatment systems similar to that described in previous sections for Outfall
002. Figure 19 shows where hypothetical capture locations for the creeks would be
located. It is assumed that PMPA is the driving influent PFAS for GAC utilization, that
99% removal is required, and that the average influent concentration for Willis Creek and
Georgia Branch Creek would be 540 ng/L and 900 ng/L, respectively. Due to the distance
between the two creeks, they would be entirely separate systems. Treated flows would be
discharged back into the respective creeks or directly into the Cape Fear River.

TR0795 51 November 2019

Figure 19: Willis Creek and Georgia Branch Creek Drainage Areas and Hypothetical Capture Locations

TR0795 52 November 2019
Schedule

Conceptual Cost
Costs were estimated and considered to be accurate within the +50/-30 % range. A NPV
calculation was performed using a discount factor of 3.5 %. The construction costs range
from $53 to 114 million, annual O&M costs are $4.6 to 9.8 million, with a 20-year NPV
for the alternative ranging from $120 to 260 million.
3.6.2 Application of PlumeStop™ to Length of Willis Creek and Georgia Branch Creek
A PlumeStop™ barrier would be installed along both sides of Willis Creek and its
tributaries. This would result in approximately 22 miles of barrier (11 miles each side).
A second barrier would be installed along Georgia Branch and its tributaries resulting in
approximately 14.25 miles of barrier (7.12 miles each side). The barrier would be
designed to retard the flow of site specific PFAS for a minimum of 20 years. At the end
of the design life additional product could be injected to extend the life of the barrier if
required.

Planning and Feasibility 6
Preliminary Design 6
Permitting Plan 2
Final Design 12
Permits/Approvals (1)12
Contracting 3
Construction (2)18
Startup Testing 2
1- Dependent upon agency approval timing.
2 - Includes construction of treatment system and new site conveyance network.
Task Duration
(months)Year 1 Year 2 Year 3 Year 4 Year 5

TR0795 53 November 2019
Schedule

Conceptual Cost
Costs were estimated and considered to be accurate within the +50/-30 % range. A NPV
calculation was performed using a discount factor of 3.5 %. The construction costs range
from $1.7 to 3.7 billion, annual O&M costs are $360,000 to 780,000, with a 20-year NPV
for the alternative ranging from $1.7 to 3.7 billion.
3.7 Pathway: Offsite Groundwater
3.7.1 Hydraulic Containment and Treatment
This alternative would mitigate the flux of offsite groundwater into the Cape Fear River
via the installation of steel sheet piles coupled with hydraulic containment of
groundwater. The steel sheeting would be installed on both sides of the river and would
primarily serve to cut off the interface between groundwater and surface water,
preventing the undesired extraction of river water. Groundwater would be extracted from
vertical recovery wells, pumped to treatment systems, and then discharged to the river.
A conceptual layout is provided in Figure 20 which shows the 20 miles (10 miles on each
side, 6 upstream and 4 downstream) of sheet piling. Note that the onsite portion of this
alignment is excluded as this is covered by other alternatives. This alignment represents
the extent of HFPO-DA concentrations in offsite residential wells with concentrations
between 140 - 1,400 ng/L (On and Offsite Assessment, Geosyntec 2019b). At least 120
acres of riverine land, much of it wetlands, would be required to site the sheet piling,
extraction wells, piping trenches, and access roads. The installation depth was estimated
to be 50 ft bgs in order to key into the Upper Cape Fear confining unit.
Work Plan Preparation 3
NCDEQ Review1 3
Access / Right-of-Way 60
Pre-design Data Collection 60
Injection and Mix Design 54
Injection Permitting2 57
PlumeStop Inections 60
Performance Monitoring 20 years
1 - Task timing is dependent upon agency approval timing
2 - Task timing is dependent upon permitting process and assumes multiple permits
Year 5TaskDuration
(months)Year 1 Year 2 Year 3 Year 4 Year 6 Year 7 Year 8 Year 9 Year 10

TR0795 54 November 2019

Figure 20: Conceptual Layout of a Hypothetical Offsite Groundwater Remedy

TR0795 55 November 2019
There would be significant challenges to implementing these continuous runs of sheet
pile, including but not limited to obtaining access agreements, permitting extensive
impacts to wetlands, and the availability of 5.3 million square feet (SF) of steel within the
time constraints of the project. For the purposes of this evaluation, it was assumed that
these challenges could be overcome.
Based on drawdown requirements to reduce head below the river stage using analytical
methods, it was estimated that 3,520 extraction wells at a spacing of 30 ft, each pumping
15 gpm, would be required. This would result in approximately 38 MGD of extracted
groundwater on each side of the river (76 MGD total). Due to the scale of the remedy
both in terms of flow rate and distance along the river, it was assumed that eight separate
treatment systems would need to be constructed to manage the water.
Conceptual design of the hydraulic piping (head loss, etc.) and the treatment system
(MMF and GAC skids, etc.) is similar in nature to that described in Section 3.4.3. It is
assumed that PMPA is the driving influent COC for GAC utilization, that 99% removal
is required, and that the average influent concentration would be 172 ng/L. Discharge
would require regulatory approval via NPDES permits, and construction of outfalls in the
vicinity of the river would likely require regulatory approval from the USACE.
Schedule
The estimated timeframe to implement a remedy of this scale would be 7 to 10 years.
This includes up to two years for design, one year for permitting after design is complete,
and four to five years for drilling, site work, and treatment system installation.

1 - Task timing is dependent upon agency approval timing
Conceptual Cost
Costs were estimated and considered to be accurate within the +50/-30 % range. An NPV
calculation was performed using a discount factor of 3.5 %. The construction costs range
from $0.7 to 1.5 billion, annual O&M costs are $41 to 89 million, with a 20-year NPV
for the alternative ranging from $1.3 to 2.8 billion.
Pre-design Investigation 6
Detailed Design 24
Permitting1 12
Contracting 6
Drilling 12
Site Work Installation 48
Treatment System Installatio 12
Testing and Commissioning 24
Year 5TaskDuration(months)Year 1 Year 2 Year 3 Year 4 Year 6 Year 7 Year 8 Year 9 Year 10

TR0795 56 November 2019
4 ASSESSMENT OF REMEDIES
This section presents an assessment and scoring of the alternatives described in Section
3 using the framework described in Section 2. This assessment is performed on a per
pathway basis. For each pathway subsection, the alternatives identified are listed, and
then for alternatives not advanced, an explanation is provided. Each subsection also
includes a table summarizing the characteristics and attributes of the alternatives
(estimated reductions, costs, timeframes) and scores them against the criteria outlined in
Section 2.
4.1 Old Outfall 002
The remedial alternative considered for Old Outfall 002 is Alternative A: Capture and
Treat Old Outfall 002. This action was as shown in Table 4 and advanced per Chemours’s
compliance with provisions in Consent Order Paragraph 12. The other alternative
identified and tested for Old Outfall 002 was PlumeStop™. PlumeStop™ was not
described here since Chemours has already proposed moving forward with the Capture
and Treat alternative. The PlumeStop™ alternative, though able to initially reduce
concentrations, may experience diminishing performance over time and may result in re-
release of sorbed Table 3+ PFAS.

TR0795 57 November 2019
Table 4: Assessment of Old Outfall 002 Alternatives

TR0795 58 November 2019
4.2 Groundwater Seeps
Remedial alternatives considered for groundwater seeps that could potentially reduce
PFAS loadings to the Cape Fear River within 2 and 5 year timeframes are listed below
and the assessment presented in Table 5:
• Alternative A: Flow-Through Cells – Cape Fear River Seeps (Interim and
Long Term)
• Alternative B: Ex Situ Capture French Drains – Cape Fear River Seeps
(Interim and Long Term)
• Alternative C: PlumeStop™ – Cape Fear River Seeps A and B (Interim)
• Alternative D: Flow-Through Cells – Willis Creek Seeps (Long Term)
• Alternative E: PlumeStop™ – Willis Creek Seeps (Long Term)

Alternative A and B, flow-through cells and ex situ capture French drains, for Cape Fear
River Seeps A, B, C and D were advanced for further consideration, with both
Alternatives proposed as interim actions likely leading to long term implementation of
one of the options (see Section 5.1). Both approaches have the potential to reduce by 95%
the loading from the seeps to the Cape Fear River within a 2 to 3 year time period.
Alternative C, PlumeStop™ application on an interim basis to the perched zone seepage
of seeps A and B was not advanced. Alternatives A & B performed on an interim basis
can achieve greater reductions than Alternative C at a lower cost. Additionally,
PlumeStop™ would only marginally reduce the mass and flow rate of the seeps going
into the river and could extend the life of ex situ treatment at captured seeps
downgradient. However, it is noted that PlumeStop™ has been demonstrated to be
effective in reducing flux of PFAS, and is generally retained for future consideration at
the Site.
Alternatives D and E, Flow-Through Cells and PlumeStop™ for Willis Creek Seeps, were
not advanced. Both alternatives are estimated to result in a 2% reduction in loading to
Willis Creek and a 0.1% reduction to the Cape Fear River. In contrast, the onsite
groundwater remedy advanced further consideration in Section 4.3 is estimated to result
in reductions to Willis Creek Loadings of 65% at lower costs per percentage reduction
achieved.

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Table 5: Assessment of Groundwater Seep Alternatives

TR0795 60 November 2019

4.3 Onsite Black Creek Aquifer Groundwater
Remedial alternatives considered for Onsite Black Creek Aquifer Groundwater that could
potentially reduce loadings to the Cape Fear River within a five year timeframe are listed
below and the assessment presented in Table 6:
• Alternative A: Extract from Black Creek Monitoring Wells (Interim);
• Alternative B: Install New Black Creek Extraction Wells (Interim);
• Alternative C: Groundwater Extraction (Long Term); and
• Alternative D: Groundwater Extraction with Barrier Wall (Long Term).

For interim alternatives, Alternative A is proposed as an interim measure in Section 6 as
it can be implemented relatively quickly. Alternative B was not selected as an interim
measure at this time since it would take longer to implement, and its efficacy has not yet
been evaluated using a numerical groundwater model.
Alternatives C and D, groundwater extraction and groundwater extraction with a barrier
wall, were both advanced for further consideration, and the alternative finalization
sequence for onsite groundwater is assessed in Section 6.

TR0795 61 November 2019
Table 6: Assessment of Onsite Black Creek Aquifer Groundwater Alternatives

TR0795 62 November 2019
4.4 Outfall 002
Remedial alternatives considered for Outfall 002 that could potentially reduce loadings
to the Cape Fear River within two and five years are listed below and the assessment
presented in Table 7:
• Alternative A: Conveyance Network Sediment Removal;
• Alternative B: Stormwater Pollution Prevention Plan;
• Alternative C: Targeted Stormwater Control;
• Alternative D: Terracotta Pipe Decommissioning;
• Alternative E: Groundwater Intrusion Mitigation;
• Alternative F: Treat all stormwater at Outfall 002; and
• Alternative G: Treat all flows at Outfall 002.

The five actions represented in Alternatives A through E were advanced as proposed
actions in the Reduction Plan (Geosyntec 2019a). Together these actions have the
potential with iterative assessment and control to provide a high degree of Total Table 3+
PFAS reductions to Outfall 002.
Alternative F, treat all stormwater at Outfall 002, was not advanced. It would be an
exceedingly disruptive remedy to implement at an active manufacturing plant as it would
require extensive reorganization of the many facilities and the non-contact cooling water
and process water supply networks. Similarly, Alternative G, treat all flows at Outfall
002, was not advanced. It would necessitate treatment of all non-contact cooling water
flows in addition to all stormwater flows at the Site.
Rather, the five actions represented in Alternatives A through E were proposed since they
have the potential to capture much of the reductions that F or G would accomplish by
targeting sources of PFAS entering the Outfall. Alternatives F and G do not provide
reductions commensurate with their cost and are economically infeasible.

TR0795 63 November 2019
Table 7: Assessment of Outfall 002 Alternatives

TR0795 64 November 2019
4.5 Willis Creek and Georgia Branch Creek
Remedial alternatives considered for Willis Creek and Georgia Branch Creek that could
potentially reduce loadings to the Cape Fear River within a five-year timeframe are listed
below and the assessment presented in Table 8:
• Alternative A: Treatment of Onsite Black Creek Aquifer groundwater prior to
discharging to Willis Creek;
• Alternative B: Treatment of all flows at the mouths of the creeks; and
• Alternative C: Application of PlumeStop™ along the length of each creek

For Alternative A, an onsite Black Creek Aquifer groundwater remedy is described in
more detail in Section 4.3. This option was selected for further evaluation.
For Alternative B, treating all flows at the mouths of the creeks was not advanced. It
would be disruptive to the local habitat, alter local wildlife patterns and challenging to
construct (e.g., obtaining access to private lands) in the desired timeframe. These
remedies were also not advanced since they do not provide reductions commensurate with
their cost and were thus economically infeasible. Order of magnitude costs were
$86,000,000 and $84,000,000 for Willis and Georgia Branch Creek, respectively, over a
20-year period, or expressed another way, $12,000,000 and $24,000,000 per loading
percentage reduction to the Cape Fear River. As shown in Figure 21 and Figure 22 and
described below in Section 0, these two remedies have vastly diminishing returns
compared to proposed and provisional remedies.
For Alternative C, Applying PlumeStop™ to the length of the Creeks was also not
advanced. While hypothetically this option could reduce PFAS loadings to each creek
and by extension the Cape Fear River, the option would be challenging and have
significant potential future issues. First, this option would disrupt local ecosystems along
the length of each creek. Second, the sorptive capacity of PlumeStop™ diminishes over
time and less strongly sorbing compounds would begin to desorb at greater rates than
they had initially accumulated and reach the stream. Last, the costs and value for applying
this option were not commensurate with its benefits. Screening level order of magnitude
costs that were developed estimate that costs could be $1,500,000,000 for Willis Creek
and $990,000,000 for Georgia Branch Creek or expressed another way, $240,000,000 and
$310,000,000 per loading percentage reduction to the Cape Fear River.

TR0795 65 November 2019
Table 8: Assessment of Willis and Georgia Branch Creek Alternatives

TR0795 66 November 2019

While no offsite alternative was advanced for either creek, both creeks will overtime have
declining PFAS concentrations as a result of air control technology improvements to
reduce aerial PFAS emissions from the Site. These actions will reduce aerial PFAS
emissions by 99% leading to offsite aerial deposition reductions and consequently
reductions over time in groundwater that discharges to these creeks.
4.6 Cost vs. Performance Assessment of Alternatives
The benefit of Cape Fear River PFAS loading reductions per alternative versus cost
expended was assessed by dividing the base case estimated cost of each remedy by the
estimated reductions to the Cape Fear River. These values are described in the subsections
of this section and presented below in Table 9. To further assess the benefit of alternatives
versus their costs, a cumulative cost and loading reduction scenario was evaluated by
selecting alternatives for each pathway and then plotting the cumulative reductions to the
Cape Fear River and the cumulative costs as remedies were added to the scenario.
Proposed alternatives are those proposed in the August 26, 2019 Reduction Plan, while
provisional alternatives are those where Chemours is advancing alternative selection.
Also included in the evaluation are remedies not selected due to technological and
economic infeasibility. These data are plotted in Figure 21 and Figure 22 and provided in
Table 9.
The plot clearly shows that the presently proposed and provisional alternatives provide
significantly more value for cost expended then alternatives not selected. Additionally,
these proposed and provisional alternatives are projected to achieve considerable
reductions in Total Table 3+ PFAS loadings to the Cape Fear River and surrounding
creeks. Meanwhile remedies not selected for advancement have diminishing returns
compared to proposed and provisional remedies.

TR0795 67 November 2019

Table 9: Cost Benefit Summary for Remedy Scenario Evaluation

TR0795 68 November 2019

Figure 21: Cost-Benefit Analysis (Cumulative – Zoomed in x-axis extent) For Remedial Alternative with Conceptual Costs
Note: Data plotted are provided in Table 9

TR0795 69 November 2019

Figure 22: Cost-Benefit Analysis (Cumulative – Full x-axis extent) For Remedial Alternative with Conceptual Costs
Note: Data plotted are provided in Table 9

TR0795 70 November 2019
4.7 Offsite Groundwater
The remedial alternative considered for offsite groundwater was Alternative A: Offsite
Groundwater Extraction with Barrier Wall. The assessment for this alternative is
presented in Table 10. This alternative was not advanced. This alternative would be
exceedingly complicated to implement as it would require access to numerous,
contiguous private property parcels to build a wall that could stop groundwater flow.
Additionally, the length of the wall and the size of the extraction systems would result in
significant complexity to install and operate. The length of the wall built adjacent to the
Cape Fear River would also be disruptive to local habitat and wildlife. Last, this remedy
was not advanced since it does not provide reductions commensurate with its cost and
was thus economically infeasible. The estimated order of magnitude costs was
$1,900,000,000 (1.9 billion dollars) over a 20-year period, or expressed another way,
$170,000,000 (170 million dollars) per loading percentage reduction to the Cape Fear
River. As shown in Figure 22 and described in Section 0, this alternative has incredibly
diminished returns compared to other proposed and provisional remedies for other
pathways.
While no offsite groundwater alternative was advanced, over time offsite groundwater
will have declining PFAS concentrations as a result of air control technology
improvements to reduce aerial PFAS emissions from the Site. These actions will reduce
aerial PFAS emissions by 99% leading to offsite aerial deposition reductions and
consequently reductions over time in groundwater that discharges to the Cape Fear River.

TR0795 71 November 2019
Table 10: Assessment of Offsite Groundwater Alternative

TR0795 72 November 2019
5 PROPOSED SEEPS INTERIM ACTIONS AND ALTERNATIVE
SELECTION SEQUENCE
This section describes the interim actions Chemours proposes to implement for
groundwater Seeps A, B, C and D reaching the Cape Fear River at the Site. This section
also describes how Chemours proposes to implement a long-term alternative.
5.1 Proposed Interim Actions
Chemours proposes to implement a combination of flow-through cells and ex situ capture
using French drains. The flow-through cell interim actions would start at Seep A with
implementation progressing successively through Seeps B and C where lessons learned
from the construction and operation of the flow-through cells at the prior seeps would be
used to design and operate the subsequent flow-through cells.
An ex-situ capture French drain would be installed at Seep D. This method, while more
power intensive and disruptive to habitats does have a higher certainty for water treatment
capabilities and would serve as a pilot location of this option.
- Seep A  Flow-Through cell – Phase 1
- Seep B  Flow-Through cell – Phase 2
- Seep C  Flow-Through cell – Phase 3
- Seep D  French Drain (to Old Outfall 002 treatment system)
5.2 Alternative Selection Sequence
Chemours proposes operating the interim seep actions for a period of two years during
which the performance of each approach can be monitored and optimized. Then
Chemours proposes selecting an approach as the long-term remedy. A combined schedule
for implementation of the interim and long-term seep remedies is shown below in Table
11 (note that this sequence is generalized, and notable assumptions about permit and
agency approvals are noted).

TR0795 73 November 2019

Table 11: Schedule for Proposed Interim Actions for Seeps
Bench Scale Testing and Lab Analysis 2
Design, Work Planning and Permitting (1)2
Agency Approvals (2)2
Clearing and Grubbing 1
Access Road Construction 1
Electrical Service 5
Seep A Flow Through Cell Construction and Pilot 6
Seep D French Drain Construction and Pilot 6
Seeps B and C Flow Through Cells Construction 6
Evaluation of Initial Performance at Seeps A - D 6
Optimization/Replacement of Cells/Drains as Needed 12
Ongoing Operations and Maintenance 18
1- Permits include but may not be limited to 404/401 and NPDES
2 - Task timing is dependent upon agency approval timing
Task Duration
(months)Year 1 Year 2 Year 3 Year 4 Year 5

TR0795 74 November 2019
6 PROPOSED ONSITE GROUNDWATER INTERIM ACTIONS AND
ALTERNATIVE SELECTION SEQUENCE
This section describes the interim action Chemours proposes to implement for onsite
Black Creek Aquifer groundwater. Then this section describes how Chemours proposes
to implement a long-term alternative.
6.1 Proposed Interim Actions
Chemours proposes extraction of groundwater from existing onsite wells as described in
Section 3.4.1. This extraction would continue until a more permanent long-term remedy
is operational unless otherwise improved, modified or demonstrated to be ineffective by
subsequent analyses or evaluations.
6.2 Alternative Selection Sequence
Chemours’s contractors are presently constructing a detailed numerical groundwater
model to quantitatively evaluate Site groundwater flow. This groundwater model will be
used to assess the efficacy and viability of groundwater alternatives under consideration
and refine these proposed alternatives. Nevertheless, to address the requests from DEQ
and CFRW a groundwater remedy similar in concept to that described in Section 3.4.4
(Barrier Wall and Groundwater Capture) will be utilized for this evaluation. A combined
schedule for implementation of the interim and a long-term onsite groundwater
alternative is shown below in Table 12 (note that this sequence is generalized, and notable
assumptions about permit and agency approvals are noted).

TR0795 75 November 2019
Table 12: Implementation schedule for On-Site Groundwater

Interim - Design and Work Planning for Pumping from Existing MWs 2
Interim - Installation and Operation 6
Contingent Action Based on Interim Performance Monitoring 12
Numerical Modeling of Permanent Onsite GW Remedy 1
Pre-Design Investigations 6
Detailed Design and Permitting (1)12
Permits/ Agency Approvals (2)12
Contracting 3
Drilling and Aquifer Pump Testing 6
Sheet Pile Installation 20
Trenching and Piping Installation 24
System Installation 24
Testing and Commissioning 12
1- Permits include but may not be limited to 404/401 and NPDES
2 - Task timing is dependent upon agency approval timing
Year 5Year 4TaskDuration
(months)Year 1 Year 2 Year 3

TR0795 76 November 2019
7 SUMMARY
This Supplemental Report describes the evaluation process for assessing potential
remedies for the Site including: potential interim measures to reduce PFAS mass loadings
from onsite seeps and onsite groundwater to the Cape Fear River on an accelerated
timeframe; provisional remedial approaches under consideration and subject to more
extensive evaluation to reduce onsite groundwater PFAS mass loading to the Cape Fear
River; and remedial options that were considered but not advanced.
This remedial alternative evaluation used information developed in the mass loading
model, which was based on two sampling events. Future sampling and updates may
produce additional data. In addition, the Table 3+ PFAS compounds at the Site have only
been recently considered for environmental remediation, and the availability of treatment
technologies is limited at this time; this is a rapidly evolving field and new technologies
may become available. Therefore, it is critical that the set of remedial alternatives
considered for this Site be subject to enhancement over time based on continued
improvement of the conceptual site model and emerging treatment technologies for Table
3+ PFAS.
Table 13 describes the estimated performance and tentative schedule for proposed interim
remedies and initial conceptual designs for long-term remedial strategies as both are
closely integrated.
The onsite groundwater remedy approaches presented here are provisional. Chemours’s
contactors have been preparing a numerical groundwater model to evaluate Site
groundwater flows and will use this model to evaluate the technological feasibility of
potential groundwater control options. The results of the model and the implications for
the finalization of actions for expedited reductions of PFAS loadings to surface water will
be provided in conjunction with the CAP that will be submitted by December 31, 2019.
The remedy screening and evaluation has been rigorous but also conducted under a
compressed timeframe. Further, remedy selection may be adjusted to account for
changing site conditions and adaptive management of a complex selection of remedies.

TR0795 77 November 2019

Table 13: Overall Estimated Reductions Plan Schedule and Reductions to Cape Fear River Total Table 3+ PFAS Loadings

TR0795 78 November 2019

8 REFERENCES
Arnold and Porter, 2019. Letter re. Chemours PFAS Loading Reduction Plan. October 7,
2019.
Geosyntec, 2019a. Cape Fear River PFAS Loading Reduction Plan. Chemours
Fayetteville Works. 26 August 2019.
Geosyntec, 2019b. On and Offsite Assessment. September 30, 2019.
Geosyntec, 2019c. Cape Rear River PFAS Mass Loading Model Assessment and
Paragraph 11.1 Characterization of PFAS at Intakes. Chemours Fayetteville
Works. 26 August 2019.
Geosyntec, 2019d. Seeps and Creeks Investigation Report. Chemours Fayetteville
Works. 26 August 2019
Geosyntec, 2019e. Assessment of HFPO-DA and PFMOAA in Outfall 002 Discharge
and Evaluation of Potential Control Options. August 26, 2019.
Geosyntec, 2019f. Summary of Grouting of East-West Section of Terracotta Pipe from
Chemours Monomers IXM Area. August, 2019.
Parsons, 2019a. Chemours Fayetteville Engineering Alternatives Analysis (EAA) for
NPDES Permit Application – Old Outfall 002 Discharge. July 2019.
Parsons, 2019b. Chemours Fayetteville Engineering Report on Wastewater Treatability.
July 2019.
Parsons, 2019c. Chemours Fayetteville Engineering Report Old Outfall 002 GAC Pilot
Study Results. September 2019.

TR0795 November 2019
APPENDIX A

Remedy Costing Tables

TR0795 i November 2019
APPENDIX A
Remedy Costing Tables
Preliminary cost estimates were developed to support the evaluation of remedial
alternatives. Cost estimation can take a range of variations, and the relative accuracy of a
cost reaches more clarity as final designs are prepared. For each proposed alternative,
construction and annual operating costs (if applicable) are estimated. The cost is then
normalized to a 20-year net present value using a 3.5% discount rate. Alternatives are
estimated as -30 percent (%) to +50%.
As noted elsewhere, treatment technologies for PFAS compounds are an emerging field
and as such there is more uncertainty than in more conventional treatment technologies.
Many of the costs rely on the use of granular activated carbon, and this material is also
subject to cost fluctuations, which may have significant impacts on total costs over time.
There are new technologies emerging but these have not been tested on the Site associated
PFAS and have not been included in this assessment.
Cost estimates are not intended for budgetary or future planning purposes.
The table below summarizes the Alternatives that have been proposed in the
Supplemental Report
TR0795 ii November 2019 Page Pathway Potential Alternative Interim (Y/N) Report Section Costing Evaluation 1 Old Outfall 002 Capture and Treat Old Outfall 002 N 3.2 Rough Order of Magnitude 2 Seeps Flow Through Cells CFR Seeps Y 3.3.1 Rough Order of Magnitude 3 Seeps Ex Situ Capture French Drain and Treatment CFR Seeps Y 3.3.2 Rough Order of Magnitude 4 Seeps Plume Stop CFR Seeps A and B Y 3.3.3 Conceptual 5 Seeps Flow Through Cells CFR Seeps N 3.3.4 Rough Order of Magnitude 6 Seeps Flow Through Cells WC Seeps N 3.3.4 Rough Order of Magnitude 7 Seeps Ex Situ Capture and Treatment CFR Seeps N 3.3.5 Rough Order of Magnitude 8 SeepsPlumeStop WC SeepsN3.3.6 Conceptual9 On-Site Groundwater Extract from Black Creek Monitoring Wells Y 3.4.1 Rough Order of Magnitude 10 On-Site Groundwater Install New Black Creek Extraction Wells Y 3.4.2 Rough Order of Magnitude 11 Outfall 002 Conveyance Network Sediment Removal N 3.5.1 Rough Order of Magnitude Outfall 002 Targeted Stormwater Control N 3.5.3 Rough Order of Magnitude 12 Outfall 002 Groundwater Intrusion Mitigation N 3.5.5 Conceptual 13 Outfall 002 Treat all stormwater at Outfall 002 N 3.5.6 Rough Order of Magnitude 14 Outfall 002 Treat all flows at Outfall 002 N 3.5.7 Rough Order of Magnitude 15 Creeks Treat all Flows at Willis Creek Mouth N 3.6.1 Conceptual 16 Creeks Treat all Flows at Georgia Branch Creek Mouth N 3.6.1 Conceptual 17 Creeks PlumeStop™ along Willis Creek Length N 3.6.2 Conceptual 18 Creeks PlumeStop™ along Georgia Branch Creek Length N 3.6.2 Conceptual 19 & 20 Off-SiteGroundwater Groundwater Extraction with Barrier WallN 3.7.1 Conceptual
Rough Order of Magnitude Cost Estimate for Treatment at Old Outfall 002 Chemours Fayetteville Works, North Carolina
Basis of Cost Estimate (Scope and Assumptions):
Direct Discharge-750 gpm without Iron Removal, No Pre-Fab Building
Scaled costs used from 1000 gpm (Using six-tenths rule of cost estimation)
Item Qty Unit Unit Cost Total Notes
Construction Costs
Influent & Effluent Handling 108,000$ 108,000$
Multi Media Filtration 331,000$ 331,000$
Granular Activated Carbon 1,239,000$ 1,239,000$
Solids Handling and Chemical Precipitation 1,074,000$ 1,074,000$
Prefabricated Building & Containment Structure -$ -$
Land Costs -$ -$
Raw Construction  Costs 2,752,000$
Installation Cost (Construction, Site Preparation, Civil, Structural)60% of Raw Construction Costs 1,700,000$
Anciliary Cost (I&C, Piping‐Mechanical & Electrical)
40% of Sum of Raw
Construction Costs and
Installation Cost
1,800,000$
Total Construction Cost
Sum of Raw Construction
Costs, Installation Cost
and Anciliary Cost
6,300,000$
Professional Services Costs
Engineering and Project Management 12%of
Total Construction
Cost 800,000$
Construction Management, Project Management, General Conditions 8%of
Sum of Total
Construction Cost,
Engineering/PM &
Contingency Costs 800,000$
Professional Services Subtotal 1,600,000$
Contingency 30%of
Sum of Total
Construction Cost and
Engineering/PM cost 2,200,000$
C0,Construction Cost 10,100,000$              
+50%15,150,000$              
‐30%7,070,000$                
Annual Operations & Maintenance Costs 
Electricity 26,680$ 26,680$
GAC Usage & Replacement 552,000$ 552,000$
Chemicals for treatment (Acid, Caustic, Ferric, Polymer)27,000$ 27,000$
Solids Disposal 25,000$ 25,000$
Sampling & Analytical 53,000$ 53,000$
Operational Labor 450,000$ 450,000$
Equipment Maintenance 237,000$ 237,000$
Annual O&M Subtotal 1,400,000$
C,Annual Cost 1,400,000$                
+50%2,100,000$
‐30%980,000$
n,Years 20
r,Discount Rate 3.5%
Present Worth Formula
Total: Present Worth Value of  Construction & Annual O&M Costs over 20 
Years 30,000,000$              
+50%45,000,000$
‐30%21,000,000$
Costs are rough order of magnitude estimates, and assumed to represent the actual installed cost within a range of ‐30%/ +50% of the value 
indicated above. The estimates have been prepared for guidance in project evaluation and implementation from the information available at the 
time of the estimate. The final costs of the project will depend on final approved design, actual labor and material costs, and competitive variable 
factors. These estimates are not intended for budgetary or future planning purposes; they have been prepared to facilitate an inter‐remedial 
alternative comparison.
Process Package
Process Package
Process Package
Process Package
Process Package
Package
November 20191
Rough Order of Magnitude Cost Estimate for Interim Seep Flow Through Cells
Chemours Fayetteville Works, North Carolina
Basis of Cost Estimate (Scope and Assumptions):
IM:  Seeps A, B, C, and D Flow Through Structures
See supporting document for treatment scenario, assumptions, and drawing
Item Qty Unit Unit Cost Total Notes
Construction Costs
Road Installation Along River 1 Lump 500,000$ 500,000$
Clearing, Grubbing, and Seep Access 4 Seep 10,000$ 40,000$
Sheet Pile Installation 1,800 ft2 40$ 72,000$
Gabion Baskets and Frame (1 frame and 3 baskets per seep)4 Seep 6,200$ 24,800$
First Install GAC Seep A 3,742 Pound 1.75$ 6,549$
First Install GAC Seep B 3,742 Pound 1.75$ 6,549$
First Install GAC Seep C 3,742 Pound 1.75$ 6,549$
First Install GAC Seep D 3,742 Pound 1.75$ 6,549$
Raw Construction  Costs 662,995$
Total Construction Cost
Sum of Raw Construction
Costs, Installation
Cost and Anciliary
Cost
700,000$
Professional Services Costs
Engineering and Project Management 12%of
Total Construction
Cost 100,000$
Construction Management, Project Management, General Conditions 18%of
Sum of Total
Construction Cost,
Engineering/PM &
Contingency Costs 200,000$
Professional Services Subtotal 300,000$
Contingency 30%of
Sum of Total
Construction Cost
and
Engineering/PM
cost 300,000$
C0,Construction Cost 1,300,000$                
+50%1,950,000$                
‐30%910,000$ 
Annual Operations & Maintenance Costs 
GAC Usage & Replacement 97,297 pound 1.75$ 170,270$
GAC Changeout Equipment and Labor 12 event 3,200.00$ 38,400$
Brush clearing and Path Maintenance 12 monthly 2,500$ 30,000$
Solids Disposal 4 event 640$ 2,560$
Sampling & Analytical (monthly performance sampling)12 month 17,200$ 206,400$
Operational Labor 4 event 7,500$ 30,000$
Equipment Maintenance 1 event 5,000$ 5,000$
Road Maintenance 1 event 5,000$ 5,000$
Storm Damage Repair and Gabion Replacement 1 event 24,800$ 24,800$
Annual Data Management and Performance Reporting 1 event 35,000$ 35,000$
Annual O&M Subtotal 550,000$
C,Annual Cost 550,000$ 
+50%825,000$
‐30%385,000$
Costs are rough order of magnitude estimates, and assumed to represent the actual installed cost within a range of ‐30%/ +50% of the value 
indicated above. The estimates have been prepared for guidance in project evaluation and implementation from the information available at 
the time of the estimate. The final costs of the project will depend on final approved design, actual labor and material costs, and competitive 
variable factors. These estimates are not intended for budgetary or future planning purposes; they have been prepared to facilitate an inter‐
remedial alternative comparison.
November 20192
Rough Order of Magnitude Cost Estimate for Interim
Seeps Ex Situ Capture using French Drains
Chemours Fayetteville Works, North Carolina
Basis of Cost Estimate (Scope and Assumptions):
IM:  Seeps A, B, C, and D Capture and Treat using French Drains
See supporting document for treatment scenario, assumptions, and drawing
Item Qty Unit Unit Cost Total Notes
Construction Costs
Road Installation Along River 1 lump 500,000$ 500,000$
Treatment Plant Expansion to Handle Additional 300 gpm Flow 1 lump 6,800,000$ 6,800,000$
Pipeline and Power Installation Along River 5,900 linear ft 29$ 171,100$
Lift Station at south end 1 lump 25,000$ 25,000$
Clearing, Grubbing, and Seep Access 4 Seep 10,000$ 40,000$
French Drain Installation 1,440 ft2 42$ 60,480$
Sump Pump Installation 4 Seep 2,980$ 11,920$
Feeder Electrical and discharge Line Seep A 800 linear ft 29$ 23,200$
Feeder Electrical and discharge Line Seep B 720 linear ft 29$ 20,880$
Feeder Electrical and discharge Line Seep C 670 linear ft 29$ 19,430$
Feeder Electrical and discharge Line Seep D 910 linear ft 29$ 26,390$
Raw Construction  Costs 7,698,400$
Total Construction Cost
Sum of Raw Construction
Costs, Installation
Cost and Anciliary
Cost
7,700,000$
Professional Services Costs
Engineering and Project Management 12%of
Total Construction
Cost 1,000,000$
Construction Management, Project Management, General Conditions 18%of
Sum of Total
Construction Cost,
Engineering/PM &
Contingency Costs 2,100,000$
Professional Services Subtotal 3,100,000$
Contingency 30%of
Sum of Total
Construction Cost
and
Engineering/PM
cost 2,700,000$
C0,Construction Cost 13,500,000$              
+50%20,250,000$              
‐30%9,450,000$                
Annual Operations & Maintenance Costs 
Electrical Power 25,000 lump 25,000$
GAC Usage & Replacement 90,000 pound 1.75$ 157,500$
Brush clearing and Path Maintenance 12 monthly 2,500$ 30,000$
Solids Disposal 12 event 320$ 3,840$
Sampling & Analytical (monthly performance sampling)12 month 17,200$ 206,400$
Operational Labor 12 event 7,500$ 90,000$
Equipment Maintenance 1 event 11,900$ 11,900$
Road, Pipe, and Power Maintenance 1 event 35,000$ 35,000$
Storm Damage Repair and Pump Replacement 1 event 21,920$ 21,920$
Annual O&M Subtotal 590,000$
Annual Cost 590,000$ 
+50%885,000$
‐30%413,000$
Costs are rough order of magnitude estimates, and assumed to represent the actual installed cost within a range of ‐30%/ +50% of the value 
indicated above. The estimates have been prepared for guidance in project evaluation and implementation from the information available at 
the time of the estimate. The final costs of the project will depend on final approved design, actual labor and material costs, and competitive 
variable factors. These estimates are not intended for budgetary or future planning purposes; they have been prepared to facilitate an inter‐
remedial alternative comparison.
November 20193
Conceptual Cost Estimate for PlumeStop Application to Seeps
Chemours Fayetteville Works, North Carolina
Basis of Cost Estimate (Scope and Assumptions):
Interim Measure (IM) for Seeps A and B
Plume Stop in Perched Zone (See Attached Diagram)
  ‐5 year design life for PRB ; no reapplication
  ‐ Seep A 900 LF; treatment zone is proximately 8 to 18 feet bgs.  
  ‐ Seep B 1,900 LF; treatment zone is aproximately 12 to 16 feet bgs.  
Item Qty Unit Unit Cost Total Notes
Construction Costs
Design Verification Testing LS 120,000$ 120,000$
Install Perfomrance Monitoring Wells LS 50,000$ 50,000$
Regenesis Costs LS 7,000,000$ 7,000,000$
-$
-$
Total Construction Cost 7,170,000$
Professional Services Costs
Engineering and Project Management 12%of
Total Construction
Cost 900,000$
Construction Management, Project Management, General Conditions 18%of
Sum of Total
Construction Cost,
Engineering/PM &
Contingency Costs 2,000,000$
Professional Services Subtotal 2,900,000$
Contingency 30%of
Sum of Total
Construction Cost
and
Engineering/PM
cost 2,500,000$
C0,Construction Cost 12,600,000$              
+50%18,900,000$              
‐30%8,820,000$                
Annual Operations & Maintenance Costs 
Annual GW Sampling LS 100,000$ 100,000$
Annual Reporting LS 30,000$ 30,000$
-$
-$
-$
-$
-$
Annual O&M Subtotal 130,000$
C,Annual Cost 130,000$                    
+50%195,000$
‐30%91,000$
Costs are conceptual estimates, and assumed to represent the actual installed cost within a range of ‐30%/ +50% of the value indicated above. 
The estimates have been prepared for guidance in project evaluation and implementation from the information available at the time of the 
estimate. The final costs of the project will depend on final approved design, actual labor and material costs, and competitive variable factors. 
These estimates are not intended for budgetary or future planning purposes; they have been prepared to facilitate an inter‐remedial 
alternative comparison.
November 20194
Rough Order of Magnitude Cost Estimate for Permanent Seeps Flow Through Cells
Chemours Fayetteville Works, North Carolina
Basis of Cost Estimate (Scope and Assumptions):
Seeps A, B, C, and D Flow Through Structures
See supporting document for treatment scenario, assumptions, and drawing
Item Qty Unit Unit Cost Total Notes
Construction Costs
Road Installation Along River 1Lump 500,000$ 500,000$
Clearing, Grubbing, and Seep Access 4 Seep 10,000$ 40,000$
Sheet Pile Installation 1,800 ft2 40$ 72,000$
Gabion Baskets and Frame (1 frame and 3 baskets per seep)4 Seep 6,200$ 24,800$
First Install GAC Seep A 3,742 Pound 1.75$ 6,549$
First Install GAC Seep B 3,742 Pound 1.75$ 6,549$
First Install GAC Seep C 3,742 Pound 1.75$ 6,549$
First Install GAC Seep D 3,742 Pound 1.75$ 6,549$
Raw Construction  Costs 662,995$
Total Construction Cost
Sum of Raw Construction
Costs, Installation
Cost and Anciliary
Cost
700,000$
Professional Services Costs
Engineering and Project Management 12%of
Total Construction
Cost 100,000$
Construction Management, Project Management, General Conditions 18%of
Sum of Total
Construction Cost,
Engineering/PM &
Contingency Costs 200,000$
Professional Services Subtotal 300,000$
Contingency 30%of
Sum of Total
Construction Cost
and
Engineering/PM
cost 300,000$
C0,Construction Cost 1,300,000$                
+50%1,950,000$                
‐30%910,000$ 
Annual Operations & Maintenance Costs 
GAC Usage & Replacement 97,297 pound 1.75$ 170,270$
GAC Changeout Equipment and Labor 12 event 3,200.00$ 38,400$
Brush clearing and Path Maintenance 12 monthly 2,500$ 30,000$
Solids Disposal 4event 640$ 2,560$
Sampling & Analytical (monthly performance sampling)12 month 17,200$ 206,400$
Operational Labor 4 event 7,500$ 30,000$
Equipment Maintenance 1 event 5,000$ 5,000$
Road Maintenance 1 event 5,000$ 5,000$
Storm Damage Repair and Gabion Replacement 1 event 24,800$ 24,800$
Annual Data Management and Performance Reporting 1 event 35,000$ 35,000$
Annual O&M Subtotal 550,000$
C,Annual Cost 550,000$ 
+50%825,000$
‐30%385,000$
n,Years 20
r,Discount Rate 3.5%
Present Worth Formula
Total: Present Worth Value of  Construction & Annual O&M Costs over 20 
Years 10,000,000$              
+50%15,000,000$
‐30%7,000,000$
Costs are rough order of magnitude estimates, and assumed to represent the actual installed cost within a range of ‐30%/ +50% of the value 
indicated above. The estimates have been prepared for guidance in project evaluation and implementation from the information available at 
the time of the estimate. The final costs of the project will depend on final approved design, actual labor and material costs, and competitive 
variable factors. These estimates are not intended for budgetary or future planning purposes; they have been prepared to facilitate an inter‐
remedial alternative comparison.
November 20195
Rough Order of Magnitude Cost Estimate for Willis Creek Seep Flow Through Cells
Chemours Fayetteville Works, North Carolina
Basis of Cost Estimate (Scope and Assumptions):
Willis Creek Seeps Flow Through Interim Measure
See supporting document for treatment scenario, assumptions, and location map
Item Qty Unit Unit Cost Total Notes
Construction Costs
Clearing, Grubbing, and Seep Access 3 Seep 4,200$ 12,600$
Hand Excavation of Seep Channels 5' long, 8" wide, 4" deep 3 Seep 500$ 1,500$
Geotube construction 3 geotube 350$ 1,050$
First Install GAC Seep A 94 Pound 1.75$ 165$
First Install GAC Seep B 94 Pound 1.75$ 165$
First Install GAC Seep C 94 Pound 1.75$ 165$
Raw Construction Costs 15,644$
Total Construction Cost
Sum of Raw Construction
Costs, Installation
Cost and Anciliary
Cost
20,000$
Professional Services Costs
Engineering and Project Management 12%of
Total Construction
Cost 10,000$
Construction Management, Project Management, General Conditions 18%of
Sum of Total
Construction Cost,
Engineering/PM & Contingency Costs 10,000$
Professional Services Subtotal 20,000$
Contingency 30%of
Sum of Total
Construction Cost
and
Engineering/PM
cost 10,000$
C0,Construction Cost 50,000$ 
+50%75,000$ 
‐30%35,000$ 
Annual Operations & Maintenance Costs 
GAC Usage & Replacement 1,128 pound 1.75$ 1,974$
GAC Changeout Equipment and Labor 4event 3,200.00$ 12,800$
Brush clearing and Path Maintenance 12 monthly 1,500$ 18,000$
Sampling & Analytical (quarterly performance sampling)4 month 13,600$ 54,400$
Equipment Maintenance 1 event 2,550$ 2,550$
Annual O&M Subtotal 90,000$
C,Annual Cost 90,000$ 
+50%135,000$
‐30%63,000$
n,Years 20
r,Discount Rate 3.5%
Present Worth Formula
Total: Present Worth Value of  Construction & Annual O&M Costs over 20 
Years 2,000,000$                
+50%3,000,000$
‐30%1,400,000$
Costs are rough order of magnitude estimates, and assumed to represent the actual installed cost within a range of ‐30%/ +50% of the value 
indicated above. The estimates have been prepared for guidance in project evaluation and implementation from the information available at 
the time of the estimate. The final costs of the project will depend on final approved design, actual labor and material costs, and competitive 
variable factors. These estimates are not intended for budgetary or future planning purposes; they have been prepared to facilitate an inter‐
remedial alternative comparison.
November 20196
Rough Order of Magnitude Cost Estimate for Seeps Permanent
Ex Situ Capture using French Drains
Chemours Fayetteville Works, North Carolina
Basis of Cost Estimate (Scope and Assumptions):
Seeps A, B, C, and D Capture and Treat using French Drains
See supporting document for treatment scenario, assumptions, and drawing
Item Qty Unit Unit Cost Total Notes
Construction Costs
Road Installation Along River 1lump 500,000$ 500,000$
Treatment Plant Expansion to Handle Additional 300 gpm Flow 1lump 6,800,000$ 6,800,000$
Pipeline and Power Installation Along River 5,900 linear ft 29$ 171,100$
Lift Station at south end 1lump 25,000$ 25,000$
Clearing, Grubbing, and Seep Access 4 Seep 10,000$ 40,000$
French Drain Installation 1,440 ft2 42$ 60,480$
Sump Pump Installation 4 Seep 2,980$ 11,920$
Feeder Electrical and discharge Line Seep A 800 linear ft 29$ 23,200$
Feeder Electrical and discharge Line Seep B 720 linear ft 29$ 20,880$
Feeder Electrical and discharge Line Seep C 670 linear ft 29$ 19,430$
Feeder Electrical and discharge Line Seep D 910 linear ft 29$ 26,390$
Raw Construction  Costs 7,698,400$
Total Construction Cost
Sum of Raw Construction
Costs, Installation
Cost and Anciliary
Cost
7,700,000$
Professional Services Costs
Engineering and Project Management 12%of
Total Construction
Cost 1,000,000$
Construction Management, Project Management, General Conditions 18%of
Sum of Total
Construction Cost,
Engineering/PM & Contingency Costs 2,100,000$
Professional Services Subtotal 3,100,000$
Contingency 30%of
Sum of Total
Construction Cost
and
Engineering/PM
cost 2,700,000$
C0,Construction Cost 13,500,000$              
+50%20,250,000$              
‐30%9,450,000$                
Annual Operations & Maintenance Costs 
Electrical Power 25,000 lump 25,000$
GAC Usage & Replacement 90,000 pound 1.75$ 157,500$
Brush clearing and Path Maintenance 12 monthly 2,500$ 30,000$
Solids Disposal 12 event 320$ 3,840$
Sampling & Analytical (monthly performance sampling)12 month 17,200$ 206,400$
Operational Labor 12 event 7,500$ 90,000$
Equipment Maintenance 1 event 11,900$ 11,900$
Road, Pipe, and Power Maintenance 1 event 35,000$ 35,000$
Storm Damage Repair and Pump Replacement 1 event 21,920$ 21,920$
Annual O&M Subtotal 590,000$
Annual Cost 590,000$ 
+50%885,000$
‐30%413,000$
n,Years 20
r,Discount Rate 3.5%
Present Worth Formula
Total: Present Worth Value of  Construction & Annual O&M Costs over 20 
Years 22,000,000$              
+50%33,000,000$
‐30%15,400,000$
Costs are rough order of magnitude estimates, and assumed to represent the actual installed cost within a range of ‐30%/ +50% of the value 
indicated above. The estimates have been prepared for guidance in project evaluation and implementation from the information available at 
the time of the estimate. The final costs of the project will depend on final approved design, actual labor and material costs, and competitive 
variable factors. These estimates are not intended for budgetary or future planning purposes; they have been prepared to facilitate an inter‐
remedial alternative comparison.
November 20197
Conceptual Cost Estimate for PlumeStop Application to Willis Creek Seeps
Chemours Fayetteville Works, North Carolina
Basis of Cost Estimate (Scope and Assumptions):
Interim Measure (IM) for Willis Creek
Plume Stop in Surficial Zone (See Attached Diagram)
  ‐20 year design life for PRB ; no reapplication
  ‐ WC‐1  Seep 700LF, treatment zone is proximately 5 to 30 feet bgs.  
  ‐ WC‐2 & 3 Seeps 1,200 LF; treatment zone is aproximately 5 to 10 feet bgs.  
  ‐ WC‐4 Seep 700 LF; treatment zone is aproximately 5 to 10 feet bgs.  
Item Qty Unit Unit Cost Total Notes
Construction Costs
Design Verification Testing LS 200,000$ 200,000$
Install Perfomrance Monitoring Wells LS 100,000$ 100,000$
Regenesis Costs LS 28,000,000$ 28,000,000$ Quote from Regenesis
-$
-$
Total Construction Cost 28,300,000$
Professional Services Costs
Engineering and Project Management 12%of
Total Construction
Cost 3,400,000$
Construction Management, Project Management, General Conditions 18%of
Sum of Total
Construction Cost,
Engineering/PM & Contingency Costs 7,500,000$
Professional Services Subtotal 10,900,000$
Contingency 30%of
Sum of Total
Construction Cost
and
Engineering/PM
cost 9,600,000$
C0,Construction Cost 48,800,000$              
+50%73,200,000$              
‐30%34,160,000$              
Annual Operations & Maintenance Costs 
Annual GW Sampling LS 100,000$ 100,000$
Annual Reporting LS 30,000$ 30,000$
-$
-$
-$
-$
-$
Annual O&M Subtotal 130,000$
C,Annual Cost 130,000$ 
+50%195,000$
‐30%91,000$
n,Years 20
r,Discount Rate 3.5%
Present Worth Formula
Total: Present Worth Value of  Construction & Annual O&M Costs over 20 
Years 51,000,000$              
+50%76,500,000$
‐30%35,700,000$
Costs are conceptual estimates, and assumed to represent the actual installed cost within a range of ‐30%/ +50% of the value indicated above. 
The estimates have been prepared for guidance in project evaluation and implementation from the information available at the time of the 
estimate. The final costs of the project will depend on final approved design, actual labor and material costs, and competitive variable factors. 
These estimates are not intended for budgetary or future planning purposes; they have been prepared to facilitate an inter‐remedial 
alternative comparison.
November 20198
Rough Order of Magnitude Cost Estimate for Interim Groundwater
Extraction from Existing Black Creek Monitoring Wells
Chemours Fayetteville Works, North Carolina
Basis of Cost Estimate (Scope and Assumptions):
Extract GW from seven existing black creek monitoring wells for treatment
‐ BCA‐01, PW‐15R, PW‐14, BCA‐02, PIW‐09D, PW‐10DR, PW‐11
‐ Assumes OOF2 Treatment Plant has excess capacity
‐ No NPDES permitting required (covered by OOF2)
‐ Assumes 2 gpm per well (14 gpm total)
Item Qty Unit Unit Cost Total Notes
Construction Costs
Clearing and Grubbing 1 Acre 10,000$ 10,000$
Subsurface Trenching/Piping ‐ 0.5‐inch (Installed)850 Feet 22$ 18,700$
Subsurface Trenching/Piping ‐ 1‐inch (Installed)3950 Feet 24$ 94,800$
Subsurface Trenching/Piping ‐ 2‐inch (Installed)1900 Feet 29$ 55,100$
Subsurface Trenching Conduit (Installed)6700 Feet 6$ 40,200$
Sumbersible Pumps & Controls (Installed)7EA 10,000$ 70,000$
Valve Boxes/Vaults 7EA 3,000$ 3,000$
Total Construction Cost 291,800$
Professional Services Costs
Engineering and Project Management 12%of
Total Construction
Cost 100,000$
Construction Management, Project Management, General Conditions 18%of
Sum of Total
Construction Cost,
Engineering/PM &
Contingency Costs 200,000$
Professional Services Subtotal 300,000$
Contingency 30%of
Sum of Total
Construction Cost
and
Engineering/PM
cost 200,000$
C0,Construction Cost 800,000$                    
+50%1,200,000$                
‐30%560,000$                    
Annual Operations & Maintenance Costs 
Electricity LS 5,000$ 5,000$
Operational Labor LS 58,240$ 58,240$
Equipment Maintenance LS 5,000$ 5,000$
-$
-$
-$
-$
Annual O&M Subtotal 68,240$
C,Annual Cost 70,000$                      
+50%102,000$
‐30%48,000$
Costs are rough order of magnitude estimates, and assumed to represent the actual installed cost within a range of ‐30%/ +50% of the value 
indicated above. The estimates have been prepared for guidance in project evaluation and implementation from the information available at 
the time of the estimate. The final costs of the project will depend on final approved design, actual labor and material costs, and competitive 
variable factors. These estimates are not intended for budgetary or future planning purposes; they have been prepared to facilitate an inter‐
remedial alternative comparison.
November 20199
Rough Order of Magnitude Cost Estimate for Interim Groundwater
Extraction from Additional Black Creek Extraction Wells
Chemours Fayetteville Works, North Carolina
Basis of Cost Estimate (Scope and Assumptions):
Installation of additional wells to enhance pumping from onsite Black Creek aquifer wells.
The baseline interim remedy includes 7 existing monitoring wells, 2 gpm each, for a total of 14 gpm to the OOF2 Treatment Plant.
This remedy would enhance this baseline interim remedy by installing 7 additional wells to an average depth of 140 ft bgs each.
It is assumed that the new 6" diameter wells would produce 10 gpm each, and that the OOF2 Treatment Plant will have the excess capacity.
Some cost efficiencies would result from a common trench alignment (clearing/grubbing, etc.).
Wells for each treatment section will convey groundwater under pressure in a common force main up to the system.
Piping will be HDPE and trenches will be approximately 3 feet deep, and reuse of excacated soils as backfill will be permitted.
HDPE pipe sizes range from 2 to 4 inch diameter SDR 11.
Includes a 20‐year net present value cost with a 3.5% discount factor applied.
Item Qty Unit Unit Cost Total Notes
Construction Costs
Drilling Costs
Driller mobilization 1LS 5,000$ 5,000$                        Engineer's Estimate
Extraction Wells drilling and well installation (no appurtenances)980 LF 225$ 220,500$                    Engineer's Estimate
IDW 980 LF 10$ 9,800$                        Engineer's Estimate
Drilling Subtotal 235,300$                    
Site Work Costs
Subsurface Trenching/Piping ‐ 2‐inch (Installed)1,500 LF 29.00$ 43,500$                      Engineer's Estimate
Subsurface Trenching/Piping ‐ 3‐inch (Installed)3,500 LF 36.00$ 126,000$                    Engineer's Estimate
Subsurface Trenching/Piping ‐ 4‐inch (Installed)2,000 LF 45.00$ 90,000$                      Engineer's Estimate
Subsurface Trenching Conduit (installed)7,000 LF 6.00$ 42,000$                      
Sumbersible Pumps & Controls (Installed)7EA 10,000.00$ 70,000$                      Engineer's Estimate
Valve Boxes/Vaults 7EA 15,000.00$ 105,000$                    Engineer's Estimate
Site Work Subtotal 476,500$                    
Total Construction Costs 711,800$
Professional Services Costs
Modeling, Design, Work Planning 12%of 711,800$ 85,416$                      adapted from EPA Guidance
Construction Oversight 8%of 711,800$ 56,944$ adapted from EPA Guidance
Project Management 6%of 711,800$ 42,708$ adapted from EPA Guidance
Professional Services Subtotal 185,068$
Contingency 30%of 896,868$ 269,060.40$
Construction Cost 1,000,000$                
+50%1,500,000$                
‐30%700,000$                    
Annual Operations & Maintenance Costs 
Electricity 1LS 25,000$ 25,000$
Operational Labor 1LS 100,000$ 100,000$
Equipment Maintenance 1LS 25,000$ 25,000$
Annual O&M Subtotal 150,000$
Annual Cost 150,000$                    
+50%225,000$
‐30%105,000$
Costs are rough order of magnitude estimates, and assumed to represent the actual installed cost within a range of ‐30%/ +50% of the value 
indicated above. The estimates have been prepared for guidance in project evaluation and implementation from the information available at 
the time of the estimate. The final costs of the project will depend on final approved design, actual labor and material costs, and competitive 
variable factors. These estimates are not intended for budgetary or future planning purposes; they have been prepared to facilitate an inter‐
remedial alternative comparison.
November 201910
Rough Order of Magnitude Cost Estimate for Conveyance Network Sediment Removal
Chemours Fayetteville Works, North Carolina
Basis of Cost Estimate (Scope and Assumptions):
Sediment removal from the IXM Monomers cooling water channel and the open channel to Outfall 002 (design input values below).
As a simplifying assumption, it is assumed that the sediment will be removed with vacuum trucks.
Long‐reach excavators may also be used where practical.
The vacuum trucks will have 2,500 gallon capacity and will mobilize from 1‐hr away.
The vacuum trucks will remove sediment at a rate of 2,500 gal/day (one truck per day). Excavator will support each day.
The vacuum trucks/excavators will deposit the media into containment areas onsite, and waste profiling will be conducted on the collected material. 
It is assumed that ultimately the media will be loaded for transport to the WM facility in Emelle, Alabama for disposal as hazardous waste
Disposal costs are sourced from Eddie Vega at the Fayetteville Works facility.
This estimate assumes the sediment removal effort will not need to be repeated, hence no annual costs.
Design Inputs
Cooling Water Channel
Item Value Units Notes
Length 2,825 ft Scaled from site maps
Width 5 ft Scaled from site maps
Average Sediment Depth 0.167 ft Assumed
Sediment Volume 2,354 ft3 Calculated
Sediment Volume 17,610 gal Converted
Sediment Density 0.064 ton/ft3 Assumed
Mass of Sediment 151 tons Calculated
Open Channel
Item Value Units Notes
Length 3,000 ft Scaled from site maps
Width 10 ft Scaled from site maps
Average Sediment Depth 0.167 ft Assumed
Sediment Volume 5,000 ft3 Calculated
Sediment Volume 37,403 gal Converted
Sediment Density 0.064 ton/ft3 Assumed
Mass of Sediment 320 tons Calculated
Item Qty Unit Unit Cost Total Notes
Construction Costs
Vac truck operation, incl. mob/demob and onsite 11 day 1,500$ 16,504$               average of CCI and HERR
Excavator operation, incl. mob/demob and onsite 11 day 1,500$ 16,504$ Engineer's estimate
Characterization and profiling 1LS 5,000$ 5,000$ Engineer's estimate
Transportation to Emelle as haz waste 471 ton 175$ 82,352$ current rates per Chemours
Haz disposal 471 ton 71$ 33,411$ current rates per Chemours
Construction Costs 153,771$
Professional Services Costs
Design, Work Planning, and Permitting 1LS 10,000$ 10,000$ Engineer's estimate
Construction Oversight 1 LS 5,000$ 5,000$ Engineer's estimate
Project Management 1 LS 5,000$ 5,000$ Engineer's estimate
Professional Services Subtotal 20,000$
Contingency 30%of 173,771$ 52,131$
Construction Cost 230,000$ 
+50%345,000$ 
‐30%161,000$ 
Annual Operations & Maintenance Costs 
None -$
Annual O&M Subtotal -$
Annual Cost ‐$ 
+50%-$
‐30%-$
Years 20
Discount Rate 3.5%
Net Present Value (NPV) of Annual Costs over 20 Years ‐$ 
+50%-$
‐30%-$
Total Cost ‐ Construction and Annual O&M
Total: Conceptual + NPV of Annual Costs over 20 Years 230,000$ 
+50%345,000$
‐30%161,000$
Costs are rough order of magnitude estimates, and assumed to represent the actual installed cost within a range of ‐30%/ 
+50% of the value indicated above. The estimates have been prepared for guidance in project evaluation and 
implementation from the information available at the time of the estimate. The final costs of the project will depend on 
final approved design, actual labor and material costs, and competitive variable factors. 
These estimates are not intended for budgetary or future planning purposes; they have been prepared to facilitate an inter‐
remedial alternative comparison.
November 201911
Conceptual Cost Estimate for Mitigation of Groundwater Intrusion into Outfall 002
Chemours Fayetteville Works, North Carolina
Basis of Cost Estimate (Scope and Assumptions):
DuPont's non‐contact cooling water (NCCW) and steam condensate currently discharge to unlined channels and are suspected to primarily infiltrate into the ground. 
This alternative involves the collection of this NCCW and condensate and transmission directly to the Open Channel to Outfall 002.
Objective of the diversion of water is to mitigate high groundwater head in the DuPont area which is a possible cause of groundwater intrusion in the Open Channel.
It is assumed that 8 point discharges from the DuPont area will need to be connected to new piping, and trenched underground to the Open Channel about 500 LF.
It is assumed that the conveyance pipes on average will be 6‐inch diameter and constructed of HDPE.
Professional services include NPDES modification.
Item Qty Unit Unit Cost Total Notes
Construction Costs
Subcontractor Installation Costs‐Piping 6"4,000 LF 75.00$ 300,000$ 
HDPE SDR 11 ‐ 6"4,000 LF 8.43$ 33,705$ 
HDPE fusing and fittings 1LS 10,000.00$ 10,000$ 
Discharge connection to Open Channel 1 LS 50,000.00$ 50,000$ 
Site restoration 1LS 10,000.00$ 10,000$
Construction Costs 403,705$
Professional Services Costs
Design, Work Planning, and Permitting (including NPDES)15%of 403,705$ 60,556$ EPA FS Guidance
Construction Oversight 10%of 403,705$ 40,371$ EPA FS Guidance
Project Management 8%of 403,705$ 32,296$ EPA FS Guidance
Professional Services Subtotal 133,223$
Contingency 30%of 536,928$ 161,078$
Construction Cost 700,000$ 
+50%1,050,000$                
‐30%490,000$ 
Annual Operations & Maintenance Costs 
None -$
Annual O&M Subtotal -$
Annual Cost ‐$ 
+50%-$
‐30%-$
Years 20
Discount Rate 3.5%
Net Present Value (NPV) of Annual Costs over 20 Years ‐$  
+50%-$
‐30%-$
Total Cost ‐ Construction and Annual O&M
Total: Capital + NPV of Annual Costs over 20 Years 700,000$ 
+50%1,050,000$
‐30%490,000$
Costs are conceptual estimates, and assumed to represent the actual installed cost within a range of ‐30%/ +50% of the value indicated above. The 
estimates have been prepared for guidance in project evaluation and implementation from the information available at the time of the estimate. The 
final costs of the project will depend on final approved design, actual labor and material costs, and competitive variable factors. 
These estimates are not intended for budgetary or future planning purposes; they have been prepared to facilitate an inter‐remedial alternative 
comparison.
November 201912
Rough Order of Magnitude Cost Estimate for Treatment of All Stormwater at Outfall 002
Chemours Fayetteville Works, North Carolina
Basis of Cost Estimate (Scope and Assumptions):
Standard Factored Costs were assumed as follows:
Installation Cost (Including Civil/Structural) = 75% of Equipment Cost;
Ancillary Cost (I&C, Piping-Mechanical & Electrical) = 30% of Sum of Equipment & Installed Construction Costs;
Engineering Cost = 12% of the sum of Equipment, Installation & Ancillary Costs;
Contingency Cost = 30% of the sum of Equipment, Installation, Engineering & Ancillary Costs; and
CM Cost & General Conditions = 18% of the sum of Equipment, Installation, Engineering, Ancillary Cost & Contingency Costs.
Considerations and assumptions:
The influent flow from the equalization tank is assumed to be consistent.
Major process equipment is assumed to be installed within a pre-engineered building.
The chemical precipitation and solids processing systems are sized to only remove accumulated solids contained in the backwash.
PFMOAA influent concentration of 4,672 ng/l has been assumed, per data provided by Geosyntec.
It is assumed that 95% removal of PFMOAA is required and PFMOAA is the driving influent COC for GAC utilization
Item Qty Unit Unit Cost Total Notes
Construction Costs
Influent & Effluent Handling 6,700,000$ 6,700,000$ Parsons
Multi Media Filtration 950,000$ 950,000$ Parsons
Granular Activated Carbon 2,400,000$ 2,400,000$ Parsons
Solids Handling and Chemical Precipitation 600,000$ 600,000$ Parsons
Prefabricated Building & Containment Structure 5,500,000$ 5,500,000$ Parsons
Separation of Stormwater and Non Contact Cooling Water 2,000,000$ 2,000,000$ Chemours
Raw Construction  Costs 18,200,000$
Installation Cost (Construction, Site Preparation, Civil, Structural)75% of Raw Construction Costs 13,700,000$ Parsons
Anciliary Cost (I&C, Piping‐Mechanical & Electrical)
30% of Sum of Raw
Construction Costs and
Installation Cost
9,570,000$
Parsons
Total Construction Cost
Sum of Raw Construction
Costs, Installation Cost
and Anciliary Cost
41,500,000$
Professional Services Costs
Engineering and Project Management 12%of
Total Construction
Cost 5,000,000$ Parsons
Construction Management, Project Management, General Conditions 18%of
Sum of Total Construction Cost,
Engineering/PM &
Contingency Costs 10,900,000$ Parsons
Professional Services Subtotal 15,900,000$
Contingency 30%of
Sum of Total Capital &
Construction Cost and
Engineering/PM cost 14,000,000$
C0,Construction Cost 71,400,000$             
+50%107,100,000$           
‐30%49,980,000$             
Annual Operations & Maintenance Costs 
Electricity 60,000$ 60,000$ Parsons
GAC Usage & Replacement 110,000$ 110,000$ Parsons
Chemicals for treatment (Acid, Caustic, Ferric, Polymer)90,000$ 90,000$ Parsons
Solids Disposal 120,000$ 120,000$ Parsons
Sampling & Analytical 75,000$ 75,000$ Parsons
Operational Labor 900,000$ 900,000$ Parsons
Equipment Maintenance 380,000$ 380,000$ Parsons
Annual O&M Subtotal 1,800,000$
C,Annual Cost 1,800,000$               
+50%2,700,000$
‐30%1,260,000$
n,Years 20
r,Discount Rate 3.5%
Present Worth Formula
Total: Present Worth Value of  Construction & Annual O&M Costs over 20 
Years 97,000,000$             
+50%145,500,000$
‐30%67,900,000$
Costs are rough order of magnitude estimates, and assumed to represent the actual installed cost within a range of ‐30%/ +50% of the value 
indicated above. The estimates have been prepared for guidance in project evaluation and implementation from the information available at the 
time of the estimate. The final costs of the project will depend on final approved design, actual labor and material costs, and competitive variable 
factors. These estimates are not intended for budgetary or future planning purposes; they have been prepared to facilitate an inter‐remedial 
alternative comparison.
Process Package
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Process Package
Process Package
NA
November 201913
Rough Order of Magnitude Cost Estimate for Treatment of All Flows at Outfall 002
Chemours Fayetteville Works, North Carolina
Basis of Cost Estimate (Scope and Assumptions):
Standard Factored Costs were assumed as follows:
Installation Cost (Including Civil/Structural) = 75% of Equipment Cost;
Ancillary Cost (I&C, Piping‐Mechanical & Electrical) = 30% of Sum of Equipment & Installed Construction Costs; 
Engineering Cost = 12% of the sum of Equipment, Installation & Ancillary Costs;
Contingency Cost = 30% of the sum of Equipment, Installation, Engineering & Ancillary Costs; and
CM Cost & General Conditions = 18% of the sum of Equipment, Installation, Engineering, Ancillary Cost & Contingency Costs.
Considerations and assumptions:
 PFMOAA influent concentration of 232 ng/l has been assumed, per data provided by Geosyntec. 
Major process equipment is assumed to be installed within a pre‐engineered building. 
Stormwater and dry weather flow are assumed to be commingled (i.e., separation of stormwater and dry weather flow is not included).
 The influent wetwell is sized to serve as a collection well and not as a holding tank.
The chemical precipitation system is sized only to treat backwash waste to remove accumulated solids.
 It is assumed that 95% removal of PFMOAA is required and PFMOAA is the driving influent COC for GAC utilization
Item Qty Unit Unit Cost Total Notes
Construction Costs
Influent & Effluent Handling Package 1,100,000$ 1,100,000$ Parsons
Multi Media Filtration Package 3,600,000$ 3,600,000$ Parsons
Granular Activated Carbon Package 8,700,000$ 8,700,000$ Parsons
Solids Handling and Chemical Precipitation Package 600,000$ 600,000$ Parsons
Prefabricated Building & Containment Structure Package 7,600,000$ 7,600,000$ Parsons
Raw  Construction  Costs 21,600,000$
Installation Cost (Construction, Site Preparation, Civil, Structural)75% of aw Construction Cos 16,200,000$ Parsons
Anciliary Cost (I&C, Piping‐Mechanical & Electrical)
30% of Sum of Raw
Construction Costs
and Installation
Cost
11,340,000$
Parsons
Total Capital & Construction Cost
Sum of Raw Construction
Costs, Installation
Cost and Anciliary
Cost
49,200,000$
Professional Services Costs
Engineering and Project Management 12%of
Total Construction
Cost 6,000,000$ Parsons
Construction Management, Project Management, General Conditions 18%of
Sum of Total
Construction Cost,
Engineering/PM &
Contingency Costs 13,000,000$ Parsons
Professional Services Subtotal 19,000,000$
Contingency 30%of
Sum of Total
Construction Cost and Engineering/PM
cost 16,600,000$
C0, Construction Cost 84,800,000$             
+50%127,200,000$           
‐30%59,360,000$              
Annual Operations & Maintenance Costs 
Electricity 77,466$ 77,466$ Parsons
GAC Usage & Replacement 2,975,000$ 2,975,000$ Parsons
Chemicals for treatment (Acid, Caustic, Ferric, Polymer)324,855$ 324,855$ Parsons
Solids Disposal 428,828$ 428,828$ Parsons
Sampling & Analytical 75,000$ 75,000$ Parsons
Operational Labor 1,464,320$ 1,464,320$ Parsons
Equipment Maintenance 439,293$ 439,293$ Parsons
Annual O&M Subtotal 5,800,000$
C,Annual Cost 5,800,000$                
+50%8,700,000$
‐30%4,060,000$
n,Years 20
r,Discount Rate 3.5%
Present Worth Formula
Total: Present Worth Value of  Construction & Annual O&M Costs over 20 
Years 168,000,000$           
+50%252,000,000$
‐30%117,600,000$
 The influent flow is assumed to be consistent. The treatment design flowrate is based on reasonable assumptions regarding the site permeability and Geosyntec’s 
rainfall modelling data.
Costs are rough order of magnitude estimates, and assumed to represent the actual installed cost within a range of ‐30%/ +50% of the value 
indicated above. The estimates have been prepared for guidance in project evaluation and implementation from the information available at 
the time of the estimate. The final costs of the project will depend on final approved design, actual labor and material costs, and competitive 
variable factors. These estimates are not intended for budgetary or future planning purposes; they have been prepared to facilitate an inter‐
remedial alternative comparison.
Process Package
Process Package
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Process Package
Process Package
November 201914
Conceptual Cost Estimate for Capture and Treatment at Willis Creek Mouth
Chemours Fayetteville Works, North Carolina
Basis of Cost Estimate (Scope and Assumptions):
Willis Creek
See supporting document for treatment scenario, assumptions and block flow diagram
Item Qty Unit Unit Cost Total Notes
Construction Costs
Influent & Effluent Handling (Includes oxidation package for this option)660,000$ 660,000$
Multi Media Filtration 950,000$ 950,000$
Granular Activated Carbon 1,400,000$ 1,400,000$
Solids Handling and Chemical Precipitation 1,500,000$ 1,500,000$
Prefabricated Building & Containment Structure 5,100,000$ 5,100,000$
Dam Structure 68,800$ 68,800$
Raw Construction Costs 9,678,800$
Installation Cost (Construction, Site Preparation, Civil, Structural)75% of Raw Construction Costs 7,300,000$
Anciliary Cost (I&C, Piping‐Mechanical & Electrical)
30% of Sum of Raw
Construction Costs
and Installation Cost
5,100,000$
Total Construction Cost
Sum of Raw Construction
Costs, Installation Cost
and Anciliary Cost
22,100,000$
Professional Services Costs
Engineering and Project Management 12%of
Total Construction
Cost 2,700,000$
Construction Management, Project Management, General Conditions 18%of
Sum of Total
Construction Cost,
Engineering/PM &
Contingency Costs 5,900,000$
Professional Services Subtotal 8,600,000$
Contingency 30%of
Sum of Total
Construction Cost and
Engineering/PM cost 7,500,000$
C0,Construction Cost 38,200,000$              
+50%57,300,000$              
‐30%26,740,000$              
Annual Operations & Maintenance Costs 
Electricity 60,000$ 60,000$
GAC Usage & Replacement 1,700,000$ 1,700,000$
Chemicals for treatment (Acid, Caustic, Ferric, Polymer)70,000$ 70,000$
Solids Disposal 60,000$ 60,000$
Sampling & Analytical 75,000$ 75,000$
Operational Labor 800,000$ 800,000$
Equipment Maintenance 500,000$ 500,000$
Annual O&M Subtotal 3,300,000$
C,Annual Cost 3,300,000$                
+50%4,950,000$
‐30%2,310,000$
n,Years 20
r,Discount Rate 3.5%
Present Worth Formula
Total: Present Worth Value of  Construction & Annual O&M Costs over 20 
Years 86,000,000$              
+50%129,000,000$
‐30%60,200,000$
Costs are conceptual estimates, and assumed to represent the actual installed cost within a range of ‐30%/ +50% of the value indicated above. The 
estimates have been prepared for guidance in project evaluation and implementation from the information available at the time of the estimate. 
The final costs of the project will depend on final approved design, actual labor and material costs, and competitive variable factors. 
These estimates are not intended for budgetary or future planning purposes; they have been prepared to facilitate an inter‐remedial alternative 
comparison.
Process Package
Process Package
Process Package
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Package
November 201915
Conceptual Cost Estimate for Capture and Treatment at Georgia Branch Creek Mouth
Chemours Fayetteville Works, North Carolina
Basis of Cost Estimate (Scope and Assumptions):
Georgia Branch
See supporting document for treatment scenario, assumptions and block flow diagram
Item Qty Unit Unit Cost Total Notes
Construction Costs
Influent & Effluent Handling 750,000$ 750,000$
Multi Media Filtration 950,000$ 950,000$
Granular Activated Carbon 1,400,000$ 1,400,000$
Solids Handling and Chemical Precipitation 1,300,000$ 1,300,000$
Prefabricated Building & Containment Structure 5,100,000$ 5,100,000$
Dam Structure 68,800$ 68,800$
Raw Construction Costs 9,600,000$
Installation Cost (Construction, Site Preparation, Civil, Structural)75% of aw Construction Cos 7,200,000$
Anciliary Cost (I&C, Piping‐Mechanical & Electrical)
30% of Sum of Raw
Construction Costs
and Installation
Cost
5,100,000$
Total  Construction Cost
Sum of Raw Construction
Costs, Installation
Cost and Anciliary
Cost
21,900,000$
Professional Services Costs
Engineering and Project Management 12%of
Total Construction
Cost 2,700,000$
Construction Management, Project Management, General Conditions 18%of
Sum of Total
Construction Cost,
Engineering/PM &
Contingency Costs 5,800,000$
Professional Services Subtotal 8,500,000$
Contingency 30%of
Sum of Total
Construction Cost
and
Engineering/PM
cost 7,400,000$
C0,Construction Cost 37,800,000$              
+50%56,700,000$              
‐30%26,460,000$              
Annual Operations & Maintenance Costs 
Electricity 50,000$ 50,000$
GAC Usage & Replacement 1,700,000$ 1,700,000$
Chemicals for treatment (Acid, Caustic, Ferric, Polymer)60,000$ 60,000$
Solids Disposal 60,000$ 60,000$
Sampling & Analytical 75,000$ 75,000$
Operational Labor 750,000$ 750,000$
Equipment Maintenance 450,000$ 450,000$
Annual O&M Subtotal 3,200,000$
C,Annual Cost 3,200,000$                
+50%4,800,000$
‐30%2,240,000$
n,Years 20
r,Discount Rate 3.5%
Present Worth Formula
Total: Present Worth Value of  Construction & Annual O&M Costs over 20 
Years 84,000,000$              
+50%126,000,000$
‐30%58,800,000$
Costs are conceptual estimates, and assumed to represent the actual installed cost within a range of ‐30%/ +50% of the value indicated above. 
The estimates have been prepared for guidance in project evaluation and implementation from the information available at the time of the 
estimate. The final costs of the project will depend on final approved design, actual labor and material costs, and competitive variable factors. 
These estimates are not intended for budgetary or future planning purposes; they have been prepared to facilitate an inter‐remedial 
alternative comparison.
Process Package
Process Package
Process Package
Process Package
Process Package
Package
November 201916
Conceptual Cost Estimate for PlumeStop Application to Length of Willis Creek
Chemours Fayetteville Works, North Carolina
Basis of Cost Estimate (Scope and Assumptions):
Plume Stop allong Creek
  ‐20 year design life for PRB ; no reapplication
  ‐ 22 mile barrier.  
Item Qty Unit Unit Cost Total Notes
Construction Costs
Design Verification Testing LS 500,000$ 500,000$ Engineer's Estimate
Install Perfomrance Monitoring Wells LS 200,000$ 200,000$ Engineer's Estimate
Regenesis Costs 22 miiles 40,000,000$ 880,000,000$ Scaled cost est.
-$
-$
Total Construction Cost 880,700,000$
Professional Services Costs
Engineering and Project Management 12%of
Total Construction
Cost 105,700,000$
Construction Management, Project Management, General Conditions 18%of
Sum of Total
Construction Cost,
Engineering/PM &
Contingency Costs 230,900,000$
Professional Services Subtotal 336,600,000$
Contingency 30%of
Sum of Total
Construction Cost
and
Engineering/PM
cost 296,000,000$
C0,Construction Cost 1,513,300,000$ 
+50%2,269,950,000$ 
‐30%1,059,310,000$ 
Annual Operations & Maintenance Costs 
Annual GW Sampling LS 200,000$ 200,000$
Annual Reporting LS 60,000$ 60,000$
-$
-$
-$
-$
-$
Annual O&M Subtotal 260,000$
C,Annual Cost 260,000$ 
+50%390,000$
‐30%182,000$
n,Years 20
r,Discount Rate 3.5%
Present Worth Formula
Total: Present Worth Value of  Construction & Annual O&M Costs over 20 
Years 1,517,000,000$ 
+50%2,275,500,000$
‐30%1,061,900,000$
Costs are conceptual estimates, and assumed to represent the actual installed cost within a range of ‐30%/ +50% of the value indicated above. The 
estimates have been prepared for guidance in project evaluation and implementation from the information available at the time of the estimate. The 
final costs of the project will depend on final approved design, actual labor and material costs, and competitive variable factors. 
These estimates are not intended for budgetary or future planning purposes; they have been prepared to facilitate an inter‐remedial alternative 
comparison.
November 201917
Conceptual Cost Estimate for PlumeStop Application to Length of Georgia Branch Creek
Chemours Fayetteville Works, North Carolina
Basis of Cost Estimate (Scope and Assumptions):
Plume Stop allong Creek
  ‐20 year design life for PRB ; no reapplication
  ‐ 14.25 mile barrier.  
Item Qty Unit Unit Cost Total Notes
Construction Costs
Design Verification Testing LS 500,000$ 500,000$ Engineer's Estimate
Install Perfomrance Monitoring Wells LS 200,000$ 200,000$ Engineer's Estimate
Regenesis Costs 14 miiles 40,000,000$ 570,000,000$ Scaled cost est.
-$
-$
Total Construction Cost 570,700,000$
Professional Services Costs
Engineering and Project Management 12%of
Total Construction
Cost 68,500,000$
Construction Management, Project Management, General Conditions 18%of
Sum of Total
Construction Cost,
Engineering/PM &
Contingency Costs 149,600,000$
Professional Services Subtotal 218,100,000$
Contingency 30%of
Sum of Total
Construction Cost
and
Engineering/PM
cost 191,800,000$
C0,Construction Cost 980,600,000$ 
+50%1,470,900,000$                  
‐30%686,420,000$ 
Annual Operations & Maintenance Costs 
Annual GW Sampling LS 200,000$ 200,000$
Annual Reporting LS 60,000$ 60,000$
-$
-$
-$
-$
-$
Annual O&M Subtotal 260,000$
C,Annual Cost 260,000$ 
+50%390,000$
‐30%182,000$
n,Years 20
r,Discount Rate 3.5%
Present Worth Formula
Total: Present Worth Value of  Construction & Annual O&M Costs over 20 
Years 985,000,000$ 
+50%1,477,500,000$
‐30%689,500,000$
Costs are conceptual estimates, and assumed to represent the actual installed cost within a range of ‐30%/ +50% of the value indicated above. The 
estimates have been prepared for guidance in project evaluation and implementation from the information available at the time of the estimate. 
The final costs of the project will depend on final approved design, actual labor and material costs, and competitive variable factors. 
These estimates are not intended for budgetary or future planning purposes; they have been prepared to facilitate an inter‐remedial alternative 
comparison.
November 201918
Conceptual Cost Estimate for Offsite Groundwater Hydraulic Containment and Treatment
Chemours Fayetteville Works, North Carolina
Basis of Cost Estimate (Scope and Assumptions):
Steel sheet piling to cut off groundwater‐surface water interface, with hydraulic containment behind the wall and ex‐situ treatment. 
Total impacted riverine length is 20 miles (10 miles on each side of the Cape Fear river, includes upgradient and downgradient reaches). 
Average depth of sheet pile to key into the Upper Cape Fear Confining Unit is 50 feet.
This estimate did not evaluate the likelihood of sourcing such a significant quantity of steel in the time constraints of the project requirements
This estimate also assumes that access agreements and permits (notably, extensive wetlands impacts under USACE) will be obtained.
AQTESOLV parameters for Black Creek aquifer include transmissivity of 200 ft2/day, saturated thickness of 40 feet, K of 5.3 ft/day, and storativity of 0.1.
On average, each extraction well will pump 15 gpm and wells will be spaced 30 feet apart.
A total of 3,520 wells and 52,800 gpm (76 MGD) would be required for hydraulic containment.
The average PMPA concentration of the extracted groundwater is estimated to be 172 ng/L.
Extensive monitoring well network will be required to evaluate the pumping well drawdown.
Due to the scale of the containment remedy, eight (8) separate groundwater treatment plants will be built along the sections of wall
Wells for each treatment section will convey groundwater under pressure in a common force main up to the system.
Piping will be HDPE and trenches will be approximately 3 feet deep, and reuse of excacated soils as backfill will be permitted.
HDPE pipe sizes range from 2 to 24 inch diameter SDR 11.
Each treatment system will be sized at roughly 10 MGD and will treat the groundwater via adsorption.
Treated groundwater will be discharged to the Cape Fear river.
Includes a 20‐year net present value cost with a 3.5% discount factor applied.
Parameters that were estimated using RACER v 11.2.16.0 are identified below, and are fully marked‐up costs.
Item Qty Unit Unit Cost Total Notes
Construction Costs
Sheet Piling
Contractor mob and demob 1LS 250,000$ 250,000$ Sevenson
Site clearing and prep (veg clearing, grading, pits, E&S)121 ACRE 25,000$ 3,030,303$                 Sevenson
Utility location (for steel barrier and well locations)1LS 150,000$ 150,000$ Engineer's Estimate
Permanent steel sheet piling, 38 psf, furnish and install 5,280,000 SF 37$ 195,360,000$            RACER, Sevenson
Site restoration and revegetation 121 ACRE 100,000$ 12,121,212$               Engineer's Estimate
Sheet Piling Subtotal 210,911,515$            
Drilling Costs
Driller mobilization 1LS 50,000$ 50,000$ Engineer's Estimate
Extraction Wells drilling and well installation (no appurtenances)176,000 LF 225$ 39,600,000$               Engineer's Estimate
Aquifer pump testing on 25% of extraction wells 880 EA 15,000$ 13,200,000$               Engineer's Estimate
Monitoring Wells drilling and installation 58,667 LF 75$ 4,400,000$                 Engineer's Estimate
IDW 234,667 LF 10$ 2,346,667$                 Engineer's Estimate
Drilling Subtotal 59,596,667$               
Site Work Costs
HDPE SDR 11 ‐ 2"1,440 LF 1.35$ 1,941$ Engineer's Estimate
HDPE SDR 11 ‐ 4"2,880 LF 3.90$ 11,228$ Engineer's Estimate
HDPE SDR 11 ‐ 6"3,840 LF 8.43$ 32,357$ Engineer's Estimate
HDPE SDR 11 ‐ 8"8,640 LF 14.28$ 123,376$ Engineer's Estimate
HDPE SDR 11 ‐ 10"12,960 LF 22.18$ 287,425$ Engineer's Estimate
HDPE SDR 11 ‐ 12"17,280 LF 31.20$ 539,129$ Engineer's Estimate
HDPE SDR 11 ‐ 14"12,960 LF 37.61$ 487,488$ Engineer's Estimate
HDPE SDR 11 ‐ 16"18,240 LF 49.07$ 895,119$ Engineer's Estimate
HDPE SDR 11 ‐ 18"20,640 LF 62.17$ 1,283,281$                 Engineer's Estimate
HDPE SDR 11 ‐ 24"6,720 LF 110.52$ 742,686$ Engineer's Estimate
HDPE fusing and fittings 1LS 72,000.00$ 72,000$ Engineer's Estimate
3'x3'x3' Well Vault + H20‐Rated Lid (4.5x4.5x4.5)3,520 ea 12,993.00$ 45,735,360$               Engineer's Estimate
Flow Meters, Level and Pressure Transmitters 3,520 ea 1,603.00$ 5,642,560$                 Engineer's Estimate
Grundfos 3" 15SQ05‐110‐240V Submersible Pump, fittings, appurtenances 3,520 ea 2,190.58$ 7,710,854$                 Engineer's Estimate
Power poles, hardware, guy wires, excavation, wiring, transformers 192 ea 30,639.71$ 5,882,825$                 Engineer's Estimate
Local control panels 352 ea 5,000.00$ 1,760,000$                 Engineer's Estimate
Utility Connection to System 8ea 494,000.00$ 3,952,000$                 Engineer's Estimate
Subcontractor Installation Costs‐Piping 2"‐6"8,160 LF 75.00$ 612,000$ Engineer's Estimate
Subcontractor Installation Costs‐Piping 8"‐14"51,840 LF 100.00$ 5,184,000$                 Engineer's Estimate
Subcontractor Installation Costs‐Piping 16"‐24"45,600 LF 125.00$ 5,700,000$                 Engineer's Estimate
Subcontractor Installation Costs‐Well Vault 3,520 ea 5,000.00$ 17,600,000$               Engineer's Estimate
Subcontractor Installation Costs‐Electrical 1LS 1,844,000.00$ 1,844,000$                 Engineer's Estimate
Subcontractor mobilization 5%of 106,099,629$ 5,304,981$ Engineer's Estimate
Site Work Subtotal 111,404,610$            
November 201919
Conceptual Cost Estimate for Offsite Groundwater Hydraulic Containment and Treatment
Chemours Fayetteville Works, North Carolina
10 MGD Treatment Plant Cost (typical of eight)
Influent & Effluent Handling, includes lift stations, EQ tanks, feed forward 
pumps, discharge pumps 1,176,733$ 1,176,733$                 Parsons
Multi Media Filtration, includes skids and backwash pumps 1,693,783$ 1,693,783$                 Parsons
Granular Activated Carbon, includes skid, water suppy tank, backwash 
waste tank, backwash pumps 2,496,101$ 2,496,101$                 Parsons
Solids Handling and Chemical Precipitation, includes feed pumps, clarifiers, 
sludge pumps, filter press, chemicals 2,674,394$ 2,674,394$                 Parsons
Prefabricated Building & Containment Structure 9,092,938$ 9,092,938$                 Parsons
Installation Cost (Construction, Site Preparation, Civil, Structural)75% of 17,133,948$ 12,850,461$ Parsons
Anciliary Cost (I&C, Piping‐Mechanical & Electrical)30% of $ 29,984,409 8,995,323$ Parsons
10 MGD Treatment Plant Subtotal 38,979,731$
Eight 10 MGD Treatment Plants 311,837,850$
Total Construction Costs 693,750,642$
Modeling, Design, Work Planning, Site Access, and Permitting 5%of 693,750,642$ 34,687,532$               adapted from EPA Guidance
Construction Oversight 5%of 693,750,642$ 34,687,532$ adapted from EPA Guidance
Project Management 4%of 693,750,642$ 27,750,026$ adapted from EPA Guidance
Professional Services Subtotal 97,125,090$
Contingency 30%of 790,875,732$ 237,262,720$
Construction Cost 1,028,000,000$         
+50%1,542,000,000$         
‐30%719,600,000$            
Annual Operations & Maintenance Costs 
Electricity ‐ Field Equipment 1LS 4,302,000$ 4,302,000$ Engineer's Estimate
Electricity ‐ Treatment Systems 1LS 855,806$ 855,806$ Parsons
GAC Usage & Replacement 1LS 32,377,252$ 32,377,252$ Parsons
Chemicals for treatment (Acid, Caustic, Ferric, Polymer)1LS 998,440$ 998,440$ Parsons
Solids Disposal 1LS 855,806$ 855,806$ Parsons
Sampling & Analytical 1LS 1,069,757$ 1,069,757$ Parsons
Operational Labor 1LS 11,410,746$ 11,410,746$ Parsons
Equipment Maintenance 1LS 7,131,716$ 7,131,716$ Parsons
Annual O&M Subtotal 59,001,523$
Annual Cost 59,000,000$               
+50%88,502,285$
‐30%41,301,066$
Years 20
Discount Rate 3.5%
Net Present Value (NPV) of Annual Costs over 20 Years 839,000,000$            
+50%1,258,500,000$
‐30%587,300,000$
Total Cost ‐ Construction and Annual O&M
Total: Construction + NPV of Annual Costs over 20 Years 1,867,000,000$         
+50%2,800,500,000$
‐30%1,306,900,000$
Costs are conceptual estimates, and assumed to represent the actual installed cost within a range of ‐30%/ +50% of the value indicated above. 
The estimates have been prepared for guidance in project evaluation and implementation from the information available at the time of the 
estimate. The final costs of the project will depend on final approved design, actual labor and material costs, and competitive variable factors. 
These estimates are not intended for budgetary or future planning purposes; they have been prepared to facilitate an inter‐remedial alternative 
comparison.
Process Package
Process Package
Process Package
Process Package
Process Package
November 201920