OLD OUTFALL 002 REMEDIALOPTIONS PLAN
CHEMOURS FAYETTEVILLE WORKS
RCRA PERMIT NO. NCD047368642-R2-M3

Prepared for:

The Chemours Company FC, LLC
Corporate Remediation Group
22828 NC Highway 87 W
Fayetteville, NC 28306-7332

Prepared by:

PARSONS
4701 Hedgemore Drive
Charlotte, NC 28209

May 2019

Chemours PN 504552
Parsons PN 449338

OLD OUTFALL 002 REMEDIAL OPTIONS PLAN

TABLE OF CONTENTSTABLE OF CONTENTS
1.0

2.0

INTRODUCTION ................................................................................................... 1
1.1

Site Description and Background .................................................................... 1

1.2

Objectives.......................................................................................................... 1

TREATMENT AND CONTROL OPTIONS ............................................................ 2
2.1

Option 1 – Capture and Treat ........................................................................... 2
2.1.1 Isotherm Studies...................................................................................... 2
2.1.2 Permitting ................................................................................................ 2
2.1.3 Flow Projections ...................................................................................... 3
2.1.4 Capture Structure .................................................................................... 4
2.1.5 Wetlands ................................................................................................. 4
2.1.6 Proposed Treatment System ................................................................... 4
2.1.7 Proposed Pilot Scale Treatment System.................................................. 6
2.1.8 Preliminary Schedule ............................................................................... 7

2.2

Option 2 – Regenesis PlumeStop™................................................................. 8
2.2.1 Bench Scale Treatability Testing ............................................................. 8
2.2.2 Proposed Pilot Scale Testing ................................................................... 9
2.2.3 Permitting ...............................................................................................10

2.3

3.0

4.0

Option 3 – Hydraulic Control...........................................................................10

COMPARISON OF ALTERNATIVES ................................................................. 11
3.1

Technical Implementability .............................................................................11

3.2

Effectiveness ....................................................................................................11

3.3

Administrative Feasibility................................................................................12

3.4

Cost...................................................................................................................12

3.5

Summary ..........................................................................................................12

REFFERENCES .................................................................................................. 13

FIGURES
Figure 1

Site Location Map

Figure 2

Site Layout Map

Figure 3

Old Outfall 002 Proposed Capture and Treatment System Locations

Figure 4

Regenesis PlumeStop Performance Verification Testing

Figure 5

Proposed Hydraulic Control OptioniOLD OUTFALL 002 REMEDIAL OPTIONS PLAN

ACRONYMS

ACRONYMS
AcronymDefinition / Description

COConsent Order

ECBT

Empty bed contact time

EQ

Equalization

GAC

Granular activated carbon

gpm

Gallons per minute

HFPO-DA

Hexafluoropropylene oxide dimer acid (aka GenX)

IOX

Ion exchangeµS/cm

Microsiemens per centimeterµm

Micrometers

mg/L

Milligrams per liter

NCDEQ

North Carolina Department of Environmental Quality

NWP

Nationwide Permit

PFAS

Per - and polyfluoroalkyl substances

PFMOAA

Perfluoro-2-methoxyacetic acid

RAP

Remedial Action Plan

Site

Fayetteville Works Facility

USEPA

United States Environmental Protection Agencyii

OLD OUTFALL 002 REMEDIAL OPTIONS PLAN

1.0

INTRODUCTIONINTRODUCTIONOn February 25, 2019, the North Carolina Superior Court for Bladen County entered aConsent Order (CO) among The Chemours Company FC, LLC (Chemours) and theState of NC and Cape Fear River Watch to address discharges of perfluoroalkyl andpolyfluoroalkyl substances (PFAS) at the Chemours Fayetteville Works (the Site).
Among other things, the CO requires Chemours to develop a remedial plan for reducing
PFAS loading from Old Outfall 002 at the Site to the Cape Fear River.

1.1

Site Description and Background
The Site is a 2,777-acre manufacturing facility located near Fayetteville, NC in BladenCounty (Figure 1). Since 1996, several stages of environmental investigations havebeen conducted at the site under NCDEQ oversight.
Studies conducted at the Site indicate that groundwater containing PFAS constituentsfrom historic PFAS deposition is discharging to a channel on the property referred to as
the Old Outfall 002 (Figure 2). The channel historically was utilized to discharge processwastewater but was abandoned by the prior site owner when the current Outfall 002 wasconstructed in 2012. There is currently no active process wastewater discharge from theSite into this former outfall. Water in this channel ultimately discharges to the Cape Fear
River.

1.2

Objectives
Pursuant to paragraph 12.e of the CO, Chemours is required to submit a plan within 90
days of entry of the CO that analyzes the following remedial options:(1) capturing the dry weather flow at Location B (as shown in Attachment A of theCO) of Old Outfall 002 and treating the water prior to discharge; and(2) an alternative equivalent remediation method.
The treatment system for water collected at Location B is required to meet discharge
standards set by DEQ and in addition be at least 99% effective in controlling theindicator parameters (i.e., GenX (hexafluoropropylene oxide dimer acid [HFPO-DA]) andperfluoro-2-methoxyacetic acid (PFMOAA)).
Upon approval by the North Carolina Department of Environmental Quality (NCDEQ)
and Cape Fear River Watch, Chemours is required to implement one of the options by
September 30, 2020. This Plan is intended to present the currently available options inorder to meet this 90-day plan requirement.

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2.0

TREATMENT AND CONTROL OPTIONS

2.1

Option 1 – Capture and Treat

TREATMENT AND CONTROL OPTIONSParagraph 12.e.i of the CO requires Chemours to evaluate a plan in which the dryweather flow in Old Outfall 002 is captured and then treated at the Location B (Figure 3).
Based on current estimates, the dry weather flow at this location is approximately 500 to
1,000 gallons per minute (gpm). Additional flow studies are being designed to better
define the flow rate. The treatment system is expected to be designed to treat flows in
the range of 500 to 1,000 gpm based on current flow estimates.

2.1.1 Isotherm Studies
If the plan for capturing flow at Location B is selected, a treatment system must be
implemented to treat the captured flow. Parsons is currently conducting studies tocompare the efficacy of ion exchange (IOX) to granular activated carbon (GAC) for
removal of PFAS compounds from Old Outfall 002 water. These studies include GAC
isotherm studies on authentic sample volume from the lower reaches of Old Outfall 002
to gain adsorptive performance information within the anticipated influent matrix. This
information is intended to demonstrate the potential benefits and limitations of using
GAC to treat individual PFAS compounds. The studies are expected to be completed bylate May 2019.
Typical GAC utilization rates required to attain prescribed target treated PFAS
concentrations for select compounds will be estimated based on the isotherm model
results. The isotherm model results for other compounds will be used to provide effluent
characterization estimates for a range of target constituents identified in the CO. By
using authentic test volume, all isotherm model results for individual compounds
implicitly reflect matrix background effects as well as potential competitive adsorption
effects due to the presence of other PFAS / sorbable constituents.
Parsons is also testing various IOX resins for treatment of PFAS constituents throughbench-scale isotherm testing. The resins were selected based on previous studies
performed by the Cape Fear Public Utility Authority. IOX will be compared to similar
studies performed with GAC. Parsons will follow up with bench-scale column testing of
IOX if the isotherm studies show it to be superior to GAC in performance and costeffectiveness. If completed, IOX column tests will be compared to similar studies
performed with GAC.

2.1.2 Permitting
Based on the preliminary design, the following permits are anticipated to be needed tocomplete this effort:


NPDES Permit (NCDEQ)

Wetlands / 404 Permit (U.S. Corp of Engineers)Building Permit (Bladen County)Land Disturbance Permit (Bladen County)2

OLD OUTFALL 002 REMEDIAL OPTIONS PLAN

TREATMENT AND CONTROL OPTIONS

2.1.3 Flow Projections
Flow projections are based on the measured dry weather flow in the Old Outfall 002
channel. Since the dry weather flow is not anticipated to fluctuate significantly, thetreatment system is expected to be designed to treat flows in the range of 500 to 1,000
gpm. This estimate is based on flow measurements conducted at different locations in
the Old Outfall 002 channel using a salt dilution gauging. The measurement
methodology is summarized below:
Volumetric flow rates along the length of the Old Outfall 002 channel were assessed atfive locations using salt dilution gauging. Flow velocity gauging measurements werecollected as an independent assessment of volumetric flow rates at the location
designated OLDOF-2, where the Old Outfall 002 passes through a culvert. This location
is just downstream of the proposed capture point (Location B).
Assessment began at the mouth of the channel and progressed sequentially upstream
towards location OLDOF-5 (headwaters). The flow of streams was measured by dosing
the stream with a known concentration of a tracer compound chosen to be sodium
chloride. Chloride concentrations were maintained throughout the assessment below
230 milligrams per liter (mg/L), the United States Environmental Protection Agency(USEPA) acute freshwater aquatic life criteria and the North Carolina 15A NCAC 02B
Water Quality Standards for Surface Waters (USEPA, 2019; NCDEQ, 2019).
Salt solution with a known concentration was dosed into the flowing stream as a nearinstantaneous slug. The metered salt solution then mixes with the stream flow. Electricalconductivity (units of microsiemens per centimeter (µS/cm)) was measured using a
conductivity probe in both the stock salt solution and at a well-mixed point downstreamof the salt injection point. Using the known stock solution concentration and the recorded
passage of the salt-wave across the downstream measurement point, the flow rate of
the stream was calculated. Salt is a suitable tracer since it can be easily and accurately
measured in the field and it can be used at concentrations that do not impact aquatic life.
The following implementation steps were generally followed at each location:

Select gauging location. A location along the stream suitable for themeasurements was selected based on visual observations. Generally, deep
pools and obstructions were avoided and a flowing, linear channel section that is10-20 times the width of the stream was selected (moving water helps increase
mixing of the stock solution).



Calibrate conductivity probe. The conductivity probe was calibrated using
calibration solutions ranging in concentrations from 10 mg/L to 100,000 mg/L.

Record background stream conductivity. Background stream conductivity wasrecorded along the length of the stream and a background stream sample wascollected for independent laboratory verification of background stream
concentrations.

Prepare stock solution. Stock solution was prepared by mixing a known volume
of water from the stream with previously prepared sodium chloride packets ofmeasured mass. Conductivity of the stock solution was measured to verify
adequate mixing of salt mass at stream temperatures and a sample of the stock
solution was collected.

Begin dosing stream with stock solution. The stock solution was dosed
instantaneously as a slug.
3OLD OUTFALL 002 REMEDIAL OPTIONS PLAN



TREATMENT AND CONTROL OPTIONS

Measure stock solution and stream concentrations. The conductivity of thestream was recorded continuously, every 1 second, at a single downstream
location 10-20 times the width of the stream. Measurements were recorded until
the stream conductivity reached background values recorded earlier.

Further field studies (ex., Parshall Flume) to confirm the flowrate will likely be
implemented in the coming weeks prior to the development of a detailed design.

2.1.4 Capture Structure
In order to collect the base flow while allowing stormwater to bypass the system, aconcrete diversion and overflow structure along with a sump will be constructed tocapture the base flow from the channel at Location B. Submersible pumps will be
installed in the sump to transfer the water from Location B to a treatment plant
constructed in the upland area to the north (Figure 3). In order to allow for variations in
the base flow, the capture system will be designed to capture and pump up to the baseflow (500 to 1,000 gpm). The dam will be equipped with a spillway to allow flows greaterthan base flow (i.e., stormwater) to bypass the system and continue downstream.
This system is relatively straightforward to design and construct and should require
limited maintenance. However, because construction will occur within the creek, aSection 404 permit must be obtained from the US Army Corp of Engineers. Also, as partof the permitting process, both the creek and the surrounding area will require wetland
mitigation.

2.1.5 Wetlands
To comply with required wetlands permitting at Old Outfall 002, we investigated the useof a Nationwide Permit (NWP #38) in lieu of an individual permit. NWP #38 was
established to address the cleanup of hazardous and toxic waste sites. This permit may
be applicable to the Fayetteville site. In anticipation of this, Parsons has alreadymapped wetlands in the area and is reviewing impacts to potential cultural resources.
In order to determine the applicability of NWP #38, Parsons had discussions with
officials at the Wilmington, NC branch of the US Army Corps of Engineers. For the
instream structure at Old Outfall 002, there was a discussion of possible implications of astructure in the stream bed. The creation of an instream weir protected by articulatingmats and rip-rap was discussed. The advantage of the articulating mats would include:
armoring the weir from stormwater events, the reduced potential for head-cuts from theriver, and impact minimization from backwater flooding from the Cape Fear River.
According to the Corps, since this instream structure would be substantial, would besemi-permanent, 1 and would likely be present after the current NWPs expire, it is likelythat an Individual Permit would be required. Chemours is working with the Corps todetermine if a permit can be issued in the timeframe established by the CO.

2.1.6 Proposed Treatment System
Parsons’ preliminary evaluation indicates that the treatment system for captured
groundwater would consist of the following unit processes:

1 The CO requires that following the completion of groundwater remediation, Chemours shall remove any

dam placed within Old Outfall 002 and restore the channel to its condition prior to the installation of thedam.
4OLD OUTFALL 002 REMEDIAL OPTIONS PLAN

Equalization (EQ)

Chemical precipitation and settling (if required)

Filtration



PFAS adsorption
•

GAC

•

IOX – if required

Clear well

Sludge holding and dewatering (if required)

TREATMENT AND CONTROL OPTIONSThe unit treatment processes are described below.
EQ. The EQ system will be designed to attenuate variations in influent flow rates andtarget constituent concentrations. Sizing for the EQ system for the Old Outfall 002
treatment system will preliminarily consider variations in measured flow rates and target
constituent concentrations in the stream flow to achieve a desired level of attenuationthat will be determined during the design process. The EQ system will include thenecessary tankage to provide the desired level of hydraulic retention plus associatedequipment and instruments/controls including such elements as transfer pumps, level
control, and interlocks with downstream processes.
Chemical Precipitation / Clarification (If Required). Chemical precipitation will be
implemented to remove target (if applicable) and nuisance constituents (e.g., iron), if
necessary, to prevent fouling downstream in the PFAS adsorption process. Testing isunderway to determine if this treatment step will be required. This unit treatment
process, if implemented, will preliminarily consist of the following steps:

Aeration to oxidize soluble ironChemical addition including pH adjustment and, if necessary, coagulant

Flocculation (assisted with polymer addition)Settling

Iron oxidation will take place in a dedicated process vessel fitted with an aeration
diffusion grid supplied by rotary-type blowers and supplemented with pH adjustment
chemicals including caustic (e.g., sodium hydroxide) and acid (e.g., sulfuric acid)metering and chemical coagulant solution addition. The flow will proceed to a lamella
clarifier to facilitate removal of precipitated iron solids. Treated flow will proceed tofiltration; settled solids will be transferred by an underflow sludge pump to a sludge
holding tank.
Filtration. Treated flow from the lamella clarifier will undergo filtration to prevent
suspended/fugitive solids from fouling the downstream PFAS adsorption process. The
type of filter (e.g., pressurized versus gravity) and media will be evaluated during thedesign process. The filtration system would be equipped with differential pressure
monitoring to trigger filter backwash. Backwash flow would be directed to the head ofthe equalization system.
PFAS Adsorption. PFAS removal will be accomplished using GAC adsorption followed, if
warranted based on treatment testing results, by IOX. Based on related GAC adsorption
studies, the treatment objectives described in Section 1.2, and estimated influent
5OLD OUTFALL 002 REMEDIAL OPTIONS PLAN

TREATMENT AND CONTROL OPTIONS

conditions based on the results from sampling at Location B in June 2018, up to 500,000
pounds of GAC will be required per year. Utilization estimates will be refined uponreceipt of influent sampling results performed in March 2019 and once focused isotherm
studies performed using authentic water from Lower Old Outfall 002 are completed(anticipated to be completed in early June 2019).
It is anticipated that skid-based contactor systems (e.g., Calgon Mod12) would be
utilized. To maximize GAC utilization, installation and operation of two or more sets ofdual contactor systems operated in series (i.e., effluent from first set proceeds throughthe second set, and so on) will be considered. The carbon units within each set would be
operated in lead-lag fashion. The schedule and criteria for replacement of GAC for each
set of contactors will be developed during the construction and startup phase.
Post-Adsorption Filtration. Treated flow from the adsorption treatment process will
undergo filtration to further reduce solids in the treated effluent and prevent
suspended/fugitive solids from building up in the downstream clear well, if warranted
based on pilot testing operation. The type of filter (e.g., pressurized versus gravity) andmedia will be evaluated during the design process. The filtration system would beequipped with differential pressure monitoring to trigger filter backwash.
Clear Well. The system will preliminarily include a treated water clear well. The clear well
will allow treated water to be held and returned to the head of the plant in the event thetreated water does not meet discharge criteria.
Sludge Holding and Dewatering (If Required). If a chemical precipitation system isrequired, then sludge holding and dewatering will also be required. It is anticipated thesludge solids would undergo thickening either in a gravity settler or by other means. The
thickened solids would then be dewatered. The thickening and dewatering technologies
and associated equipment (e.g., thickened sludge transfer pumps, polymer addition) will
be evaluated during the design phase. Liquid removed during thickening and dewatering
will be transferred back to the EQ system. Dewatered solids cake would be managed /disposed in a manner which takes into account the potential association of PFAS
constituents with the sludge solids.
System Interlocks. In addition to local controls, interlocks will be instituted among various
processes to prevent conditions such as overflows and out-of-spec discharges, which
would be determined based on real-time instrument readings. For example, influent
pumps will automatically shut down if the level in the EQ system exceeds a high-levelset point, and transfer pumps will automatically shut off if tank levels drop below lowlevel set points.

2.1.7 Proposed Pilot Scale Treatment System
CO paragraph 12.e also requires that Chemours complete pilot scale testing of the
proposed treatment equipment to determine its control efficiency for all PFAS
constituents identified in the Old Outfall 002 water. The pilot testing must be completed
by September 30, 2019, be supported by three months of sampling data, and besubmitted to NCDEQ for review and approval.
The proposed pilot scale treatment system will be constructed within the plant site since
there are currently no facilities (power, water, etc.) at the proposed full-scale capture andtreatment location. Water will be collected from the proposed capture location andtrucked to the plant site, stored in tanks and pumped through the system. Treated water
will then be transported off-site for disposal with other process wastewaters. Solids
6OLD OUTFALL 002 REMEDIAL OPTIONS PLAN

TREATMENT AND CONTROL OPTIONS

residuals, if applicable, will be managed / disposed consistent with state and location
regulations taking into consideration potential association of PFAS constituents with thesolids residue.
The treatment system will be sized to treat approximately 0.25 – 0.5 gpm and will consistof similar components to the full-scale system described above. The pilot scale system
will be operated initially without an iron removal component and at native pH. Thesesystems will be added later if required or warranted based on technical efficacy oroperability concerns (e.g., iron fouling in PFAS adsorption process). The overall system
will preliminarily consist of the following components:
An equalization (raw water holding) tank(s), sufficient to provide up to four (4)days of storage capacity.

Transfer pump(s), including:•Centrifugal (submerged or dry-mounted) or peristaltic pump to transfer
water through PFAS adsorption process (bypass pre-treatment)•

Centrifugal pump to transfer water through chemical precipitation pretreatment, followed by transfer using the aforementioned pump throughfiltration and PFAS adsorption.



Filtration, using cartridge-type filters to remove fugitive solids; may be utilized
ahead of PFAS adsorption without preceding chemical precipitation step.



PFAS Adsorption, using 3- or 4-inch diameter HDPE or PVC tubing; up to three(3) columns would be installed in series each providing approximately 7 minutesof empty bed contact time (EBCT).



Post Adsorption Filtration, as required using cartridge-type filters under pressure
or gravity-type bag/media filter.



Clearwell (treated water) storage tank, sized similarly to equalization (raw water
storage) tank.

2.1.8 Preliminary Schedule
A preliminary schedule for the project is provided below in Table (1). This scheduleassumes that permits will be issued in a timely manner by the DEQ, the U.S. Corp ofEngineers and local permitting authorities (i.e., building and land disturbance permits).

Table 1 - Preliminary Schedule
Project Milestone

Anticipated Target
Complete Date

Treatability Testing

June 2019

NPDES Permit Application

June 2019

Wetlands / 404 Permit Application

July 2019

Basis of Design

July 20197

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Table 1 - Preliminary Schedule
Project Milestone
Pilot Study Construction

2.2

Anticipated Target
Complete Date
May 2019

Pilot Study Report

September 30, 2019

Detailed Design

February 2020

Procurement

On-going

Construction Completion

August 2020

Startup and Commissioning

September 30, 2020

Option 2 – Regenesis PlumeStop™
As an alternative remediation method required by CO paragraph 12.e, Chemours is also
evaluating using PlumeStop™ to reduce PFAS flowing out Old Outfall 002.
PlumeStop™ is an innovative groundwater remediation technology designed tosequester groundwater contaminants via sorption. It is composed of very fine particles (1to 2 micrometers [µm]) of activated carbon suspended in water. The material is held insuspension through the use of proprietary organic polymers that allow easy injection anddispersion into the subsurface. As the polymer breaks down, the carbon coats the solidmaterial in the aquifer matrix creating a passive, subsurface carbon adsorption filter.
PlumeStop™ has been successfully applied to remediate other contaminants including
larger PFAS molecules; additional testing is required to determine its effectiveness intreating HFPO-DA and PFMOAA. Chemours has initiated bench scale and pilot scalestudies to assess the effectiveness of the remedial method. The material could beinstalled as a continuous barrier or combined with a cut-off wall (slurry wall) andarranged as a funnel and gate.
A combination of laboratory (bench scale) and pilot scale studies will be used to assess
the efficacy of PlumeStop™ at the site. A phased approach is proposed in order tofacilitate data collection and minimize assumptions. In phase 1, bench scale testing will
be conducted alongside a pilot scale wall to be installed in the Perched Zone beneaththe Site. The first step in this process is the collection of samples and installation ofpiezometers and monitoring wells required to gather the necessary performance data.
Chemours installed the performance verification testing wells in April 2019 andconducted an initial round of sampling to establish baseline conditions.

2.2.1 Bench Scale Treatability Testing
PlumeStop™ has been demonstrated to effectively bind PFAS compounds and similar
species in a range of conditions. Parsons will confirm that the specific indicator
constituents (HFPO-DA and PFMOAA) will bind effectively and that competitive sorption
will not reduce the effectiveness of the PlumeStop™. Therefore, the overall objective ofthe laboratory testing is to determine the efficacy of PlumeStop™ as a remediation
8

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TREATMENT AND CONTROL OPTIONS

option to treat HFPO-DA and PFMOAA, as well as other fluorinated compounds and
VOCs present in groundwater at the subject site. Specifically, the intent of the testing isto perform an isotherm with the bulk aquifer components to determine the doseresponse of PlumeStop™ for the target compounds as well as other non-target species
within the aquifer matrix. This testing will provide the Regenesis technical services teamwith site-specific dosing information to aid in a field design and to be used in a model topredict the anticipated performance of PlumeStop™ at the site.
The intent of the treatability study is to determine the dose-response of PlumeStop™ for
the target contaminants present in the samples by performing an isotherm
measurement, rather than to demonstrate complete removal of the contaminants. Six
loadings of PlumeStop™ will be used in the isotherm bench test, ranging fromapproximately 500 mg/L to 50,000 mg/L. Three of the six treated samples will be
prepared in duplicate for reproducibility verification. In addition to the PlumeStop™
treated samples, two control samples and one method control blank will also be
analyzed. The control samples will contain site soil and groundwater with no added
PlumeStop™. The method control blanks will consist of deionized water and are analytefree. They are carried through the entire process and are meant to trace any artificial
sources of contamination from the procedures.
All samples will be prepared in 4-liter high density polyethylene bottles for the sorption
batch study. Each bottle will contain 4,000 milliliters of contaminated groundwater fromthe site in addition to 0.4 kilograms of site soil. The designated amount of PlumeStop™
for each treatment level will be added to the reaction vessel, (or de-ionized water for thecontrols) and the samples will be mixed by inversion and kept at room temperature for48 hours. At this time, a settling reagent will be added. This settling reagent is a mix ofsalts formulated and tested to decrease the time needed for PlumeStop™ to destabilize
and settle out of the aqueous phase. If PlumeStop™ is not removed prior to sample
extraction, any contaminants adsorbed onto PlumeStop can be extracted during theanalytical sample preparation step and will lead to biased-high results. Additionally,
spiked surrogates will have low recoveries due to sorption onto PlumeStop™. Afterapproximately an additional 72 hours, aliquots of the samples will be centrifuged if
PlumeStop™ has not been completely removed, and PlumeStop™-free groundwatercomponent will be sent for PFAS and VOC analysis.

2.2.2 Proposed Pilot Scale Testing
In order to collect performance data, several monitoring wells and piezometers must be
installed. The pre-pilot study drilling project includes the installation of 2 soil borings (tomap out the location of the perched zone clay), 6 monitoring wells, and 4 piezometers.
The proposed boring and pilot study location is shown on Figure 4.
The next step in the pilot test involves the injection of the Regenesis PlumeStop™ into
the subsurface to construct an initial 75-foot long by 20-foot wide barrier in the perchedzone (Phase 1). Three rows of injection points (20 points each) will be used to construct
the wall with an estimated vertical treatment interval of 5.5 feet (approximately 16.5 to 22
feet below ground surface). Phase 1 will be used to determine the effectiveness of thematerial. Based on a preliminary design, the following injection rates are proposed.
Injection of the phase 1 pilot barrier began on May 8th and will be completed in mid-May.
Monthly groundwater samples will be collected from perched zone wells MW-38 through9OLD OUTFALL 002 REMEDIAL OPTIONS PLAN

TREATMENT AND CONTROL OPTIONS

MW-43 for three months following the injections to monitor the performance of thebarrier. The groundwater samples will be analyzed for HFPO-DA and PFMOAA. A
report describing the results of the bench and pilot scale testing will be submitted to
NCDEQ by September 30, 2019.
Phase 2 of the pilot study (if required) will involve the installation of a second treatment
barrier. Phase 2 will be designed based on the results of Phase 1 and will be used torefine the required application rates required for full scale implementation.

2.2.3 PermittingThis option will require obtaining an injection permit from NCDEQ. There are no otherknown permitting requirements for this option.

2.3

Option 3 – Hydraulic Control
Chemours is also considering a third possible approach. Under this third approach, asystem to cut off groundwater flow from the manufacturing area to the south toward the
Old Outfall 002 channel would be designed and installed. Reducing flow from this area
would ultimately reduce the mass of PFAS discharging to Old Outfall 002. There are atpresent two options for obtaining hydraulic control:Cut-off wall (e.g., slurry wall) with upgradient trenchGroundwater extraction from vertical or horizontal well(s)The hydraulic control system would be installed in the upgradient area north of the Old
Outfall 002 channel as shown on Figure 5. In the first option, a slurry wall would beinstalled and keyed into the clay confining unit below the Surficial Aquifer. A
groundwater extraction system would be installed just upgradient of the wall.
Groundwater would be extracted at a rate sufficient to prevent flow over the wall. The
extracted groundwater would be treated with carbon. Treated groundwater could bedischarged to the Cape Fear River or re-injected into the aquifer through injection wells
located upgradient of the wall.
Hydraulic control could also be maintained through a series of horizontal or verticalextraction points. Extracted water would be treated and discharged in a similar manneras the first option.
The slurry wall would likely result in significantly lower flow rates and thus lower
operational costs for the treatment plant as compared to hydraulic control by pumping
alone. Re-injection of the treated effluent will require a non-discharge permit from
NCDEQ; discharge to the Cape Fear River will require an NPDES permit similar to
Option 1.

10

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3.0

COMPARISON OF ALTERNATIVESCOMPARISON OF ALTERNATIVES
A complete analysis of each alternative is not practical until the two pilot studies havebeen completed. The pilot studies for Options 1 and 2 will be completed by September
30, 2019 as required by the CO. In addition, Chemours will want to incorporate any
comments and feedback on this report from NCDEQ and Cape Fear River Watch into its
selection of a proposed option. At this time, as part of the evaluation process, thescreening guidelines for conducting feasibility studies as established by the UnitedStates Environmental Protection Agency (USEPA 1988) were preliminarily considered tocompare the options. The remedial alternatives were preliminarily screened based on
the following criteria:

3.1Technical Implementability

EffectivenessAdministrative Feasibility



Cost

Technical Implementability
Technical implementability considers whether there are technical limitations that would
preclude a technology from further consideration. Examples of these limitations are
geologic or hydrogeologic conditions (e.g., a formation may not be amenable toeffectively applying technologies requiring injections), depth of impact, type of
constituents or the presence of limiting constituents (e.g., metals or conditions toxic tobacteria). At this time, there are no known technical limitations precluding any of the
proposed remedial alternatives (although such limitations could be identified during thepilot studies for options 1 and 2). The impacted groundwater is relatively shallow andaccessible. The geology and hydrogeology at the Site do not present obstacles to anyof the proposed treatment options. The technology is readily available to install a slurrywall at the required depths.

3.2

EffectivenessThe alternatives were assessed based on four effectiveness criteria:

Ability to meet remedial goals
Protection of human health and the environmentWhether the technology is proven or is an emerging technology

Reliability

The application of GAC and IOX adsorption to remove the constituents from water in an
ex-situ treatment system are proven, reliable technologies that can meet the remediation
goals and are protective of human health and the environment.
The hydraulic control option is also a proven technology with reliability comparable to thecapture and treat option. Hydraulic control would also be protective of human health andthe environment (removing PFAS before it could reach the Old Outfall 002 channel).
Capturing the groundwater before it reaches the channel will lower the surface water
concentrations in the Old Outfall 002 channel. However, the time required to reach 99%
removal under this option cannot be determined without additional data collection andmodeling. Chemours is evaluating this option and determining the data needs.
11OLD OUTFALL 002 REMEDIAL OPTIONS PLAN

COMPARISON OF ALTERNATIVESThe use of PlumeStop™ to sequester these constituents is still an emerging technology
and the pilot study is required before a complete judgement can be rendered with regard
to these criteria.

3.3

Administrative Feasibility
The evaluation of administrative feasibility covers such items as the ability to obtain
permits, the availability of resources (e.g., space, power, backfill, or other utilities), andthe availability of contractors or other suppliers required to perform the work. There are
no known administrative limitations with the hydraulic control option. There are potential
administrative limitations to capturing and treating the water (a number of permits are
required from Federal, State, and Local agencies). The application of PlumeStop™ has
no known administrative concerns.

3.4

Cost
Once the pilot studies are complete, costs will be considered in evaluating among thoseof the options that are found to meet the other selection criteria, discussed above. At
this point, the design of each option has not progressed to the point where costs can be
accurately calculated for the options.

3.5

Summary
All three options appear to be technically and administratively feasible, assuming that allnecessary approvals and permits are received in a timely fashion. Capturing andtreating the water is anticipated to be effective at removing PFAS constituents.
Additional studies are needed to estimate the effectiveness and time required to reachthe remedial goals for the two alternative options.

12OLD OUTFALL 002 REMEDIAL OPTIONS PLAN

4.0

REFFERENCES

REFFERENCESUSEPA 1988. Guidance for Conducting Remedial Investigations and Feasibility Studies
Under CERCLA. EPA/540/G-89/004. OSWER Directive 9355.3-01.

13

FIGURES¯

North Carolina

Property Boundary

USGS Topo Quad provided by NC DOT
0

0.5

1

PE&I
4701 Hedgemore Dr.
Charlotte, NC 28209

2

Miles

Site Location Map
Old Outfall 002 Remedial Options Plan
Chemours Fayetteville Works
Fayetteville, North Carolina

Bladen County
Drawn:

C. Oneal
Revision:1Date:

1/29/2018

File Project Number:
450768Figure Number: 1

Name: Fay_Fig_1_Site_Loc

D:\G IS\Fayetvle\G is\Proje ct_figures\20 17\SiteInvestiga tion \Fay_Fig _1_Site_Loc.mxd

Site

¯
Chemours
Monomers
IXM Area

Chemours
PPA Area

Cape

Kuraray America
Leased Areas

Fear

Kuraray America
Leased Areas

R i ve r

Former DuPont PMDF
Production Area

Wastewater
Treatment
Plant

DuPontLeased Area

Old Outfall 002 Channel

Drainage Network
Former DuPont PMDF Production Area
Chemours Monomers IXM Area
Chemours PPA Area

Kuraray America Leased Areas
Wastewater Treatment Plant
0

0.125

Parsons Environment & Infrastructure
4701 Hedgemore Dr.
Charlotte, NC 28209

0.25

0.5
Miles

Site Layout Map Old Outfall 002 Remedial Options
Fayetteville Works Facility
Fayetteville, North Carolina

Plant Border
Drawn:

C. Oneal
Revision:
1

Date:

5/20/2019

File Project Number:
449338.01050

Figure Number: 2

Name: Layout_OldOutfall002RemOpt

D:\GIS\Fayetvle\Gis\Project_figures\2019\Layout_OldOutfall002RemOpt.mxd

DuPont Leased Area

Cape Fear R iver¯

Treatment
Plant

Old O
utfall002
Approximate
Dam / Diversion
structure location

Treatment Plant
Drainage Network
0

250

500

Parsons Environment & Infrastructure
4701 Hedgemore Dr.
Charlotte, NC 28209

1,000
Feet

Plant Border

Old Outfall 002 Capture and Treatment Area
Old Outfall 002 Remedial Options Plan
Fayetteville Works Facility
Fayetteville, North Carolina

Drawn:
C. Oneal
Revision:1

Date:

4/8/2019

File Project Number:
449338.01050

Figure Number: 3

Name: OldOutfall002_TrtPlnt

D:\G IS\Fayetvle\G is\Proje ct_fi gures\20 19\O ldOutfa ll002_TrtPln t.mxd

Approximate Dam / Diversion structure location

¯

Approximate Location of Proposed
Perched Zone Treatment Barrier (Phase 1)
PZ-31

PZ-32
MW-31

MW-32
MW-34

MW-33

MW-3 5
PZ-34

SB-203

MW-36

PZ-33

Pilot Study Proposed
Locations (MWgroundwater level ft msl)
0

30

60

Parsons E nvironment & Infrastructure
4701 Hedgemore Dr.
Charlotte, NC 28209

120
Feet

<all other values>

Regenesis PlumeStop Performance Verification Testing
Old Outfall 002 Remedial Options Plan
Fayetteville Works Facility
Fayetteville, North Carolina

Drawn:
C. Oneal
Revision:
1Date:

5/15/2019

File Project Number:
449338.01050

Figure Number: 4

Name: RegenesisVerification_v3

D:\GI S\F ayetvle\Gis\Project_figu res\2 019 \Re gen esisVerifica tio n_v3. mxd

SB-202

¯
Cape
Fear
River
Proposed Hydraulic Control Option
Drainage Network
0

0.125

Parsons Environment & Infrastructure
4701 Hedgemore Dr.
Charlotte, NC 28209

0.25

Plant Border

0.5
Miles

Proposed Hydraulic Control Option
Old Outfall 002 Remedial Options
Fayetteville Works Facility
Fayetteville, North Carolina

Drawn:

C. Oneal
Revis ion:
1

Date:

5/10/2019

File Project Number:
449338.01050

Figure Number: 5

Name: Layout_OldOutfall002RemOpt_v2

D:\GI S\F ayetvle\Gis\Project_figu res\2 019 \Layo ut_OldOu tfall002R em Opt_ v2 .mxd

Old Outfall 002 Channel