2020.08.31_CCO.p12_PFAS MassLoadProtocol

SITE CONVEYANCE NETWORK AND
OUTFALL 002 PFAS MASS LOADING
CALCULATION PROTOCOL

Chemours Fayetteville Works

Prepared for
The Chemours Company FC, LLC
22828 NC Highway 87 Fayetteville, NC 28306
Prepared by
Geosyntec Consultants of NC, PC 2501 Blue Ridge Road, Suite 430
Raleigh, NC 27607

Project Number TR0795
August 2020
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8/31/2020

Outfall 002 Mass Load ii August 2020
TABLE OF CONTENTS
1 INTRODUCTION ................................................................................................ 1
2 OUTFALL 002 AND RIVER INTAKE SAMPLING ......................................... 2
2.1 Outfall 002 Sample Types ........................................................................... 2
2.2 River Intake Samples ................................................................................... 2
2.3 Consent Order Addendum Sampling Requirements ................................... 2
2.4 Flow Measurement Methods ....................................................................... 3
3 PFAS MASS LOADING CALCULATION METHODOLOGY ........................ 4
3.1 Total Mass Load Calculation Methodology ................................................ 4
3.2 Loading at Outfall 002 ................................................................................. 5
3.3 Loading from River Water Intake ............................................................... 5
3.4 Concentrations at Outfall 002 ...................................................................... 6
3.5 Concentrations in Site River Water Intake .................................................. 7
3.6 Potential Adjustments .................................................................................. 8

LIST OF TABLES
Table 1: PFAS Analytical Methods and Analyte List

LIST OF FIGURES
Figure 1: Outfall 002 Sampling Locations
Figure 2: Flowchart for Determining the Concentrations for Loading at Outfall 002
Figure 3: Flowchart for Determining the Concentrations for Loading at the River Water
Intake

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Outfall 002 Mass Load iii August 2020
LIST OF ABBREVIATIONS
CO Consent Order hr hour mL milliliter ng/L nanograms per liter PFAS per- and polyfluoroalkyl substances
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Outfall 002 Mass Load 1 August 2020
1 INTRODUCTION
Geosyntec Consultants of NC, PC (Geosyntec) has prepared this Protocol for establishing
current mass loading from Outfall 002 to the Cape Fear River (“Outfall 002 Trendline”)
on behalf of The Chemours Company FC, LLC (Chemours) pursuant to the requirements
of Paragraph 1(c)(ii) of the Addendum to Consent Order Paragraph 12 (CO Addendum).
The objective of this document is to describe the sampling activities and calculation
methods associated with per- and polyfluoroalkyl substances (PFAS) mass loading at
Outfall 002.
The CO Addendum specifies that PFAS mass loading calculations use the PFAS
compounds listed in Attachment C of the Consent Order (CO) (February 25, 2019). Table
1 lists the Attachment C PFAS compounds and the associated analytical methods.
Specifically, this protocol describes how the PFAS loads reaching the river at Outfall 002
from the Site conveyance network are calculated by estimating the PFAS load in river
water intake water and the PFAS load at Outfall 002. The remainder of this document is
organized as follows:
• Section 2 – Outfall 002 and River Intake Sampling, which describes the
background and protocols for sampling and flow measurements at Outfall 002;
and
• Section 3 – PFAS Mass Loading Calculation Method, which describes the
methods used to calculate loading using composite samples collected at Outfall
002.

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Outfall 002 Mass Load 2 August 2020
2 OUTFALL 002 AND RIVER INTAKE SAMPLING
This section provides an overview of the types of sampling and flow measurements
conducted at Outfall 002 and the River Intake.
2.1 Outfall 002 Sample Types
PFAS mass loading at Outfall 002 can be assessed by sampling the discharge at Outfall
002 using both 3.5-day composite samples and 24-hour (hr) composite samples as
detailed below:
• 3.5-day composite samples: 3.5-day composite samples have been collected twice
per week. Samples have been time-composited using an auto-sampler set to
collect 350-mL aliquots every three hours. The location of the auto-sampler is
shown in Figure 1.
• 24-hr composite samples: 24-hr composite samples have been collected as flow-
weighted samples. Samples have been collected using an auto-sampler set to
collect 150-mL aliquots for every 200,000 gallons of flow. The location of the
autosampler is shown in Figure 1.
On a sample-specific basis, samples collected with different composite sample durations
or grab samples may also be used to develop the PFAS mass load at Outfall 002.
2.2 River Intake Samples
The site draws water from the Cape Fear River which at the River Water intake already
contains PFAS from upstream sources. This water, after use at the Site, is then discharged
at Outfall 002. As part of the Cape Fear River PFAS Mass Loading Calculation Protocol
(Geosyntec, 2020), the River Water Intake at Facility location will be sampled as a 24-hr
composite sample once per month. The River Water Intake at the Facility location
represents water drawn in by the facility through the intake piping.
2.3 Consent Order Addendum Sampling Requirements
The CO Addendum requirements for the PFAS sampling program at Outfall 002, as
detailed in Paragraph 1(c)(i) of the CO Addendum, are as follows:
c. Outfall 002 Trendline: i. Starting no later than August 31, 2020, Chemours shall, each week for at least twelve consecutive weeks, take a 24-hour composite sample from
Outfall 002 and analyze for the PFAS listed in Attachment C to the Consent
Order. Chemours shall also conduct 24-hour composite sampling within 24 hours of any rain event predicted two days before with at least a 70%
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Outfall 002 Mass Load 3 August 2020
likelihood to be of 1 inch or greater over a 24-hour period. Chemours shall
record the flow through Outfall 002 for each sampling event. To fulfill these requirements, 24-hr composite samples will be collected weekly for at
least twelve weeks, in addition to within 24 hours of a rain event that meets the criteria
specified in the CO Addendum. Samples will be sent to an approved external laboratory
for analysis. The PFAS analyte list to be used (Table 1) includes all Consent Order
Attachment C PFAS.
2.4 Flow Measurement Methods
The flow at Outfall 002 will be measured using a flowmeter to record flow readings from
a 60-inch Parshall flume (Figure 1). Flow measurements will be translated into a flow per
time unit, such as gallons per hour. If flow measurements are unable to be collected based
on temporary equipment malfunction or other unforeseen circumstances, flow at Outfall
002 will be estimated for purposes of these calculations. For dry weather flow data gaps,
dry weather flow measurements close in time to the data gap along with facility water
usage records will be used to estimate dry weather flows at Outfall 002. If the data gaps
in flow measurement occur during wet weather, the Site hydrologic model will be used
to estimate stormwater flows at Outfall 002, and these estimates will be summed with an
estimate of the dry weather flow for that same time period. For the purposes of these
calculations, flows at the river intake are assumed to be equal to dry weather Outfall 002
flows.

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3 PFAS MASS LOADING CALCULATION METHODOLOGY
This section presents the calculation methodology to estimate PFAS mass loading at
Outfall 002. The mass loading at Outfall 002 is calculated using measured and estimated
PFAS concentrations and measured flows at Outfall 002. The mass loading in river water
at the intake is also calculated using measured and estimated PFAS concentrations, as
well as measured flows, from river water at the intake. The mass loading in river water at
the intake is then subtracted from the mass loading at Outfall 002 to determine the mass
load reaching the river at Outfall 002 from the Site conveyance network.
The calculations presented here are suitable for evaluating the mass loads of any given
set of selected PFAS. For the purposes of calculations and reporting for Paragraph 1 of
the CO Addendum, the set of PFAS will be those listed in Attachment C of the Consent
Order and listed here as Table 1.
3.1 Total Mass Load Calculation Methodology
This sub-section describes the methodology for calculating PFAS mass loading over a
given time period. The mass loads over the given time intervals will be summed, as shown
in Equation 1 below:
Equation 1: Total Mass Loading at Outfall 002 𝑀𝑀𝑂𝑂𝑂𝑂002 =�𝑚𝑚𝑂𝑂𝑂𝑂002,𝑛𝑛𝑁𝑁𝑛𝑛=1 − 𝑚𝑚𝑖𝑖𝑛𝑛𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖,𝑛𝑛
where,
• 𝑀𝑀𝑂𝑂𝑂𝑂002 = is the total PFAS mass load at Outfall 002 for a given number of time
periods “N”, as mass per time, typically pounds per day, that originated from the Site
conveyance network;
• 𝑚𝑚𝑂𝑂𝑂𝑂002,𝑛𝑛 = is the total PFAS mass load at Outfall 002 for a given time interval “n”
(mass per time), calculated by summing (or subdividing) the appropriate values of 𝑚𝑚𝑂𝑂𝑂𝑂002,𝑗𝑗;
• 𝑛𝑛= represents individual time intervals in a time period to assess mass loading at
Outfall 002;
• 𝑁𝑁= is the total number of time intervals in a time period to assess mass loading at
Outfall 002; and
• 𝑚𝑚𝑖𝑖𝑛𝑛𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖,𝑛𝑛 = is the total PFAS mass load in river water from the intake for a given
time interval “n” (mass per time), calculated by summing (or subdividing) the
appropriate values of 𝑚𝑚𝑖𝑖𝑛𝑛𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖,𝑖𝑖.
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3.2 Loading at Outfall 002
Measured and estimated concentrations, as well as measured flows at Outfall 002, are
used to calculate mass loading at Outfall 002, as shown in Equation 2 below:
Equation 2: Outfall 002 Mass Loading 𝑚𝑚𝑂𝑂𝑂𝑂002,j = 𝐶𝐶𝑂𝑂𝑂𝑂002,𝑗𝑗 × 𝑄𝑄𝑂𝑂𝑂𝑂002,𝑗𝑗 × 𝐹𝐹
=∑𝑐𝑐𝑂𝑂𝑂𝑂002,j,iI𝑖𝑖=1 × 𝑄𝑄𝑂𝑂𝑂𝑂002,j × 𝐹𝐹
where, 𝑚𝑚𝑂𝑂𝑂𝑂002 = is the total PFAS mass load at Outfall 002 as measured in mass for
a given time interval, “j”; 𝑗𝑗= is time interval (represents either full 3.5-day composite period, portion
of the 3.5-day composite period, 24-hr composite period, or time interval of
data gap [i.e., no composite sample collection], described further in Section
3.4); 𝐶𝐶𝑂𝑂𝑂𝑂002,𝑗𝑗 = is the measured or estimated total PFAS concentration at Outfall
002 for a given time interval, “j” (described further in Section 3.4); 𝑄𝑄𝑂𝑂𝑂𝑂002,𝑗𝑗 = is the total measured flow at Outfall 002 in a given time interval
“j”; and 𝐹𝐹 = is a conversion factor (to convert from concentrations in ng/L multiplied
by flow in gallons per time unit to load in pounds per time unit) c𝑂𝑂𝑂𝑂002,j,i = is the measured or estimated concentration of the ith PFAS
compound based on samples collected from Outfall 002; 𝑖𝑖= represents each of the PFAS compounds being evaluated; and 𝐼𝐼= represents total number of PFAS compounds included in the summation
of total PFAS concentrations.

3.3 Loading from River Water Intake
Measured and estimated concentrations, as well as measured flows from river water at
the intake, are used to calculate mass loading in river water at the intake, as shown in
Equation 3 below:
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Equation 3: River Intake Mass Loading 𝑚𝑚𝑖𝑖𝑛𝑛𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖,k = 𝐶𝐶𝑖𝑖𝑛𝑛𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖,𝑖𝑖 × 𝑄𝑄𝑖𝑖𝑛𝑛𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖,𝑖𝑖 × 𝐹𝐹
=∑𝑐𝑐𝑖𝑖𝑛𝑛𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖,𝑖𝑖,𝑖𝑖I𝑖𝑖=1 × 𝑄𝑄𝑖𝑖𝑛𝑛𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖,𝑖𝑖 × 𝐹𝐹
where, 𝑚𝑚𝑖𝑖𝑛𝑛𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖,𝑖𝑖 = is the total PFAS mass load in the river water at the intake as
measured in mass for a given time interval, “k”; 𝑘𝑘= is time interval for calculating the mass loading represents either the 24-
hr composite period, or time interval of data gap [i.e., no composite sample
collection], described further in Section 3.5); 𝐶𝐶𝑖𝑖𝑛𝑛𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖,𝑖𝑖 = is the measured or estimated total PFAS concentration in the river
water at the intake for a given time interval, “k” (described further in Section
3.5); 𝑄𝑄𝑖𝑖𝑛𝑛𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖,𝑖𝑖 = is the total measured flow at the intake in a given time interval “k”; 𝐹𝐹 = is a conversion factor (to convert from concentrations in ng/L multiplied
by flow in gallons per time unit to load in pounds per time unit); c𝑖𝑖𝑛𝑛𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖,k,i = is the measured or estimated concentration of the ith PFAS
compound based on samples collected from the river water at the intake; 𝑖𝑖= represents each of the PFAS compounds being evaluated; and 𝐼𝐼= represents total number of PFAS compounds included in the summation
of total PFAS concentrations.
3.4 Concentrations at Outfall 002
This section describes the methodology for estimating PFAS concentrations at Outfall
002 to be used in calculating mass loads. The methodology is also illustrated in Figure 2.
The calculation methodology outlined here considers all collected samples in a given time
period, including cases where samples are collected contemporaneously with each other
(e.g. both 3.5-day and 24-hr composites) and cases where composite sample collection
events do not occur successively (i.e., there could potentially be time gaps where a
composite sample is not being collected).
Sample concentrations will be assigned to the corresponding time period over which the
composite sample was collected (for both 3.5-day and 24-hr composite samples). If a
composite sample collected over a shorter time interval (i.e., compositing period) is
collected contemporaneously with a composite sample having a longer compositing
period, the sample result representative of the shorter compositing period will be applied
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Outfall 002 Mass Load 7 August 2020
for that compositing period. The sample result representative of the longer compositing
period will be applied to that compositing period, except for the period of time covered
by the shorter compositing period. In other words, sample results with shorter
compositing periods will take precedence over those with longer compositing periods
when sampled contemporaneously.
For example, if a 24-hr composite sample was collected during a time period where a 3.5
day composite was also collected, the concentration from the 24-hr sample will be applied
to that 24-hr period, and the 3.5-day composite result will be applied to the appropriate
period of time prior to and following the 24-hr composite time period (in other words, the
3.5-day composite result will not be applied during the time interval when the 24-hr
composite sample was collected).
If there are data gaps (i.e., where neither a 3.5-day or 24-hr composite sample is collected
during a period of time), the time period will be assessed for whether it is considered
“wet” or “dry”. Each time period with data gaps will be considered wet or dry based on
the total precipitation depth measured in the preceding 72 hours, with “wet” defined as
greater than 0.2 inches of precipitation in the preceding 72 hours (below this approximate
rainfall threshold, minimal stormwater runoff generation is expected).
A 60-day rolling average wet or dry concentration will be applied to the time periods with
data gaps based on the wet or dry designation. To calculate the 60-day rolling wet and
dry concentrations, each composite sample result at Outfall 002 (both 3.5-day and 24-hr)
will be assigned wet or dry based on the definition noted above (where samples with
greater than 0.2 inches of precipitation in the preceding 72 hours, based on the end of the
composite sample collection period, are considered wet). The 60-day rolling wet and dry
average sample concentrations will be calculated based on the sample dates reported for
each composite sample (which represent the end of the composite sample collection
period), and each sample result in the rolling 60-day period will be counted as one result
in the calculation of the average (i.e., weighted evenly), regardless of whether it is a 3.5-
day, 24-hr, or other composite sample result.
3.5 Concentrations in Site River Water Intake
This section describes the methodology for estimating PFAS concentrations in river water
at the intake to be used in calculating mass loads. The methodology is also illustrated in
Figure 3. The calculation methodology outlined here considers all collected samples in a
given time period (24-hr composites) and cases where composite sample collection events
do not occur successively (i.e., there are time gaps where a composite sample is not being
collected).
Sample concentrations will be assigned to the corresponding 24-hr time period over
which the composite sample was collected. Where there are data gaps (i.e., where no 24-
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Outfall 002 Mass Load 8 August 2020
hr composite sample is collected during a period of time), the 60-day rolling average river
water intake sample concentrations will be calculated.
3.6 Potential Adjustments
The calculation methodologies described in this section have been outlined based on the
present understanding of Site conditions. If conditions or methods change, modifications
may need to be made to this protocol. Modifications to the calculation methodologies
will be described in future submitted reports.
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TABLES

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TABLE 1
PFAS ANALYTICAL METHODS AND ANALYTE LIST
Chemours Fayetteville Works, North Carolina
Geosyntec Consultants NC P.C.
Analytical Method Common Name Chemical Name CASN Chemical Formula
HFPO-DA*Hexafluoropropylene oxide dimer acid 13252-13-6 C6HF11O3
PEPA Perfluoro-2-ethoxypropionic acid (Formerly Perfluoroethoxypropyl carboxylic acid)267239-61-2 C5HF9O3
PFECA-G Perfluoro-4-isopropoxybutanoic acid 801212-59-9 C12H9F9O3S
PFMOAA Perfluoro-2-methoxyacetic acid 674-13-5 C3HF5O3
PFO2HxA Perfluoro-3,5-dioxahexanoic acid (Formerly Perfluoro(3,5-dioxahexanoic) acid)39492-88-1 C4HF7O4
PFO3OA Perfluoro-3,5,7-trioxaoctanoic acid (Formerly Perfluoro(3,5,7-trioxaoctanoic) acid)39492-89-2 C5HF9O5
PFO4DA Perfluoro-3,5,7,9-tetraoxadecanoic acid (Formerly Perfluoro(3,5,7,9-tetraoxadecanoic) acid)39492-90-5 C6HF11O6
PMPA Perfluoro-2-methoxypropionic acid (Formerly 2,3,3,3-Tetrafluoro-2-(trifluoromethoxy)propanoic)13140-29-9 C4HF7O3
PFO5DA Perfluoro-3,5,7,9,11-pentaoxadodecanoic acid 39492-91-6 C7HF13O7
PS Acid (Formerly PFESA-BP1)Ethanesulfonic acid, 2-[1-[difluoro[(1,2,2-trifluoroethenyl)oxy]methyl]-1,2,2,2-tetrafluoroethoxy]-1,1,2,2-
tetrafluoro- (Formerly PFESA-BP)29311-67-9 C7HF13O5S
Hydro-PS Acid (Formerly PFESA-BP2)Ethanesulfonic acid, 2-[1-[difluoro(1,2,2,2-tetrafluoroethoxy)methyl]-1,2,2,2-tetrafluoroethoxy]-1,1,2,2-
tetrafluoro- (Formerly PFESA-BP2)749836-20-2 C7H2F14O5S
PFHpA*Perfluoroheptanoic acid 375-85-9 C7HF13O2
Notes:
* - HFPO-DA and PFHpA are also analyzed by EPA Method 537 Mod.
EPA - Environmental Protection Agency
PFAS - Per- and Polyfluoroalkyl substances
SOP - Standard Operating Procedure
Table 3+ Lab SOP
TR0795 Page 1 of 1 August 2020
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FIGURES

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Legend
https://projectsitesb.geosyntec.com/5/FWConsentOrder/Shared Documents/12 - Outfall 002 Reductions/2020 Misc Tasks/OF 002 Mass Loading/Tables and Figures/[Tables and Figures.xlsx]Figure 1Outfall 002 Sampling Locations
Chemours Fayetteville Works, North CarolinaSampling Location
Figure
1
Raleigh August 2020
River Water
Intake at
Facility
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Illustrator/Flow Charts/OutfallProtocol_flowchart_Sec3.4.aiFlowchart for Determining the
Concentration for Loading at Outfall 002
Chemours Fayetteville Works, North Carolina
Figure
2RaleighAugust 2020
YES
YES
Was a 24-hr composite sample collected?
Was a 3.5-day composite sample collected?
Was the time period wet (>0.2 in. rain in preceding 72 hrs)?
Was a 24-hr composite sample also collected (within the 3.5-day time period)?
YES
YES
Use 24-hr composite sample concentration*
Use 3.5-day composite sample concentration**
Use 60-day rolling average wet concentration
Use 60-day rolling average dry concentration
Use 24-hr composite sample concentration during the 24-hr period and use the 3.5-day composite sample concentration for the remaining portion of the 3.5-day period
NO
NO
NO NO
*For the 24-hr time period
**For the 3.5-day time period
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Illustrator/Flow Charts/OutfallProtocol_flowchart_Sec3.5.aiFlowchart for Determining the
Concentration for Loading at the River Water Intake
Chemours Fayetteville Works, North Carolina
Figure
3RaleighAugust 2020
Was a 24-hr composite sample collected?YES Use 24-hr composite sample concentration*
Use 60-day rolling average dry concentration
NO
*For the 24-hr time period
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