WI0500657_Monitoring (Report)_20221115

Permit which is effective through August 31, 2023. Therefore, no application for permit renewal is
included with this interim evaluation. We will also send one color copy and one CD of this report to your
attention. If you have any questions or need any additional information, please feel free to contact me
at [phone] or byuncu(@_daa.com.
Yours truly,
Draper Aden Associates, a TRC company
Bilgen Yuncu, Ph.D., P.E. William D. Newcomb, P.G., RSM
Project Manager Senior Hydrogeologist
Attachment 1: Annual Project Status Update Report
Electronic cc: Mr. Jeffrey P. Allen, P.G, Eaton, jeffpallen(a�eaton.com
Ms. Karen Souza, Allegheny Environmental Services, Inc, ksouza(@alleghenyenviron.com
UIC Permit W10500657
Former Eaton Selma Facility (REC Program ID NONCD 0002853)
DAA Project No. 017025.0000.0000
November 17, 2022
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Attachment 1: Annual Project Status Update Report

TRIC
Annual Project
Status Update
Report
Former Eaton Corporation Facility
1100 East Preston Street
Selma, Johnston County, NC 27576
Longitude W78017'02", Latitude N35031'33"
November 15, 2022
Prepared by: Bilgen Yuncu, Ph.D., P.E.
Project Manager
Eaton Selma
Prepared For:
Eaton
Mail Stop 4S, 1000 Eaton Boulevard
Cleveland, OH 44122
Prepared By:
TRC
114 Edinburgh South Drive, Suite 200
Cary, NC 27511
Reviewed and approved by: William D. Newcomb, P.G., R.S.M.
Senior Hydrogeologist

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TABLE OF CONTENTS
1.0
INTRODUCTION...............................................................................................................1
1.1 Summary of Groundwater Remedial Actions......................................................................1
2.0
GROUNDWATER SAMPLING PROCEDURES AND RESULTS....................................4
2.1 Groundwater Elevations......................................................................................................4
2.1.1 Aquifer Recognition................................................................................................4
2.1.2 Groundwater Elevation Data..................................................................................
5
2.1.3 Groundwater Potentiometric Surface and Flow Direction ......................................
5
2.2 Groundwater Sampling Procedures....................................................................................6
2.3 Groundwater Sampling Results..........................................................................................6
2.3.1 Chlorinated Organic Compound Concentrations...................................................
7
2.3.2 Field Measurements............................................................................................
10
2.3.3 Biogeochemical Laboratory Parameters..............................................................
11
2.4 Chlorine Number Calculation............................................................................................14
2.5 Mann -Kendall Statistical Analysis.....................................................................................15
3.0
QUALITY ASSURANCE/QUALITY CONTROL.............................................................15
4.0
INVESTIGATION -DERIVED WASTE.............................................................................16
5.0
CONCLUSIONS AND RECOMMENDATIONS..............................................................16
6.0
REFERENCES................................................................................................................17
FIGURES
Figure 1 Site Location Map
Figure 2 Injection Well Layout
Figure 3 Site Map
Figure 4 Shallow Groundwater Potentiometric Surface Maps — October 2013 through
July 2021
Figure 5 Shallow Groundwater Elevation Map — January 2022
Figure 6 Shallow Groundwater Elevation Map — July 2022
Figure 7 Shallow PCE Plume Maps — October 2013 through July 2021
Figure 8 Shallow PCE Plume Map — January 2022
Figure 9 Shallow PCE Plume Map — July 2022
IF_1 31: &1
Table 1 Summary of Post -Injection Monitoring and Reporting Events
Table 2 Summary of Groundwater Elevation Data
Table 3 Summary of Field Parameters in Monitoring Wells
Table 4 Summary of Analytical Laboratory Data for VOCs in Monitoring Wells
Table 5 Summary of Natural Attenuation Parameters in Monitoring Wells
Table 6 Summary of MBT and VFA Data
Table 7 Chlorine Number
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APPENDICES
Appendix A
Well Construction and Abandonment Records
Appendix B
Field Notes and Injection Logs
Appendix C
Groundwater Sampling Logs
Appendix D
Laboratory Analytical Reports
Appendix E
Mann -Kendall Statistics
Appendix F
IDW Manifest
Appendix G
CVOC Concentrations Versus Time Charts
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1.0 Introduction
Draper Aden Associates, a TRC company (DAA) prepared this Annual Project Status Update
Report for the former Eaton Corporation (Eaton) facility located at 1100 East Preston Street in
Selma, Johnston County, North Carolina, 27576 (Site). The Site is located approximately 0.5-
mile northeast of the intersection of US Highway 95 and NC Highway 70 (Figure 1). The Site is
currently occupied by Johnston County Industries, Inc. (JCI). Remedial action at the Site is
being performed under the Registered Environmental Consultant (REC) Program within the
Inactive Hazardous Sites Branch (IHSB) of the Superfund Section of the North Carolina
Department of Environmental Quality (NCDEQ).
As discussed in more detail below, permitted remedial action is currently underway at the Site
and includes a combination of in -situ enhanced bioremediation and Monitored Natural
Attenuation (MNA) to reduce chlorinated hydrocarbon mass and concentrations in groundwater.
The Groundwater Remedial Action Plan (RAP) for the Site dated June 3, 2013, and submitted
on June 7, 2013, passed public notice without comment and was certified complete on August
13, 2013 (SIES, 2013a). The Groundwater RAP recommended implementation of in -situ
bioremediation of groundwater to stimulate biodegradation of chlorinated volatile organic
compounds (CVOCs) in the areas of highest impact and Monitored Natural Attenuation (MNA)
to control migration in downgradient and side -gradient, less heavily impacted, areas of the
plume. The Pre -Construction Report dated September 16, 2013, and certified on September
17, 2013, presented the final design of the remedy (SIES, 2013b).
The remedy implementation began with well installations on September 16, 2013. Phase 1
injection activities were initiated on October 21, 2013, with the injection of a colloidal buffer
(CoBupH-Mg)', followed by an emulsified vegetable oil (EVO) product (EOS XR)', into 60
injection wells in the western portion of the Site (Figure 2). The Phase 2 injection activities
were conducted between January 20, 2014, and February 14, 2014, with injection of CoBupH-
Mg followed by EOS XR into the remaining 60 injection wells in the eastern portion of the Site
(Figure 2). The Construction Completion Report No. 1 dated January 20, 2014, described
injection into one-half of the injection network (Phase 1). The report was certified by the
Registered Site Manager (RSM) on January 15, 2014. The Construction Completion Report No.
2, dated April 9, 2014, described injection into the second half of the injection network (Phase
2), included the Construction Completion Certification Work Phase Completion Form (WPC-V)
for the Site, and was certified by the RSM on April 9, 2014.
1.1 Summary of Groundwater Remedial Actions
The Phase II Remedial Investigation Report dated February 8, 2012 (Phase II RI; SIES, 2012),
identified tetrachloroethene (PCE), trichloroethene (TCE) and 1, 1 -dichloroethene (1,1-DCE) as
the primary CVOCs of concern in groundwater. Enhanced reductive dechlorination (ERD) using
emulsified oil, time -release buffer and bioaugmentation, with MNA, were proposed in the
Groundwater RAP as a combined groundwater remedy.
' CoBupH-Mg and EOS XR were purchased from EOS Remediation, LLC of Raleigh, NC.
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The remedial goal for the Site is to reduce the concentrations of primary contaminants of
concern (COCs) to levels below the 15A NCAC 2L .0202 groundwater standards (NC 2L
Standards). Biological processes produce degradation by-products that must also be degraded.
While the primary goal is to reduce the primary CVOC concentrations to below the NC 2L
Standards, the biodegradation daughter -products of PCE, TCE and 1,1-DCE, including cis-1,2-
dichloroethene (cDCE) and vinyl chloride (VC), are also evaluated.
The Groundwater RAP required injection of a colloidal buffer, EVO, and bioaugmentation
cultures to stimulate ERD in the areas of highest impact, which lie along the stormwater
conveyance system and along East Preston Street (north and east of the facility, reference
Figure 3). The injections targeted two zones within the sand and gravel layer: Zone A,
screened from 10 to 20 feet below ground surface (ft bgs), and Zone B, screened from 23 to 30
ft bgs. The Groundwater RAP also required sampling of a performance monitoring well network
until CVOC concentrations were below the NC 2L Standard. The following 16 monitoring wells
were established as the performance monitoring well network and are shown in Figure 3:
Shallow monitoring wells: MW-1, MW-2, MW-3, MW-4, MW-5, MW-8, MW-9, MW-11,
MW-13, MW-16, MW-17, MW-18, MW-19 and MW-20;
o MW-7 was added to the monitoring program during the first post -injection
monitoring event (January 2014) to provide data for groundwater COC
concentrations north of the treated area of the Site;
o Monitoring well MW-21 was added to the monitoring program as a compliance
shallow monitoring well in July 2016;
o MW-22, MW-23, MW-24, MW-25 and MW-26 were also added to the
monitoring network as discussed later in this section;
o Monitoring well MW-11 was eliminated from the sampling schedule in August
2018.
Deep monitoring wells: MW-14 and MW-15.
Beginning in July 2016, Solutions-IES, Inc. (SIES)2 injected additional colloidal buffer (CoBupH-
Mg)3, EVO product (EOS Pro)3, and nutrients (nitrogen, phosphorus, protein, and vitamin B12)3
in the Phase 1 injection area to optimize ongoing contaminant biodegradation. Approximately
983 gallons of dilute CoBupH-Mg, 39,215 gallons of dilute EOS Pro, and 620,000 gallons of
chase water were injected into the 60 existing Phase 1 injection wells over an eleven -week
period to distribute the buffering agent and EVO throughout the treatment zone. Substrate
breakthrough was observed near monitoring well MW-16, likely the result of a localized less
permeable soil zone, such as a clay lens. Therefore, less substrate was delivered to this area.
MW-18 was originally installed as a compliance monitoring well between the treated areas along
the storm sewer and Bawdy Swamp Creek (Figure 3). Groundwater testing results from this
well have revealed an area of elevated CVOC concentrations separate from the Phase 1 and
Phase 2 treatment areas. In August 2015, SIES conducted additional site characterization
z Solutions-IES, Inc. became a division of Draper Aden Associates in March 2017.
3 EOS ZVI, EOS QR, EOS Pro, CoBupH-Mg, nutrients and BAC-9 are provided by EOS Remediation, LLC.
Potassium bicarbonate is provided by Brenntag.
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activities in the MW-18 area to identify the horizontal and vertical extent of the CVOC
concentrations (SIES, 2016). Following that assessment, Eaton elected to "spot treat"
groundwater with high CVOC concentrations in and near MW-18. DAA performed additional
injection activities in June and July 2018, including the installation of new injection and
monitoring wells and subsequent injections with glycerin (EOS QR)3, EVO (EOS Pro)3,
emulsified zero valent iron (EOS ZVI)3, vitamin B-12, pH buffers (CoBupH-Mg and potassium
bicarbonate)3, and bioaugmentation culture (BAC-9)3. The two new monitoring wells (MW-22
and MW-23) installed during the MW-18 area injections were also added to the monitoring
program in August 2018 (Figure 3). The DAA Construction Completion Report dated October
10, 2018, described well installation and injection activities. The report was certified by the
Registered Site Manager (RSM) on October 10, 2018, and included the Construction
Completion Certification Work Phase Completion Form (WPC-V) for the Site.
To address the high CVOC concentrations in groundwater, in and near MW-1, additional
injection activities were completed at the western portion of the Site including the installation of
new injection wells and their subsequent injection with EVO (EOS Pro)4 and pH buffer
(CoBupH-Mg)4 in May through August 2019. Thirty permanent injection wells (IW-66 through
IW-95) were installed at the western portion of the Site (Figure 2). MW-24, MW-25 and MW-26
were added to the monitoring program in July 2019. The bioaugmentation using BAC-94
microbial consortium was performed in September 2019. The DAA Construction Completion
Report dated November 25, 2019, described well installation and injection activities. The report
was certified by the Registered Site Manager (RSM) on December 3, 2019 and included the
Construction Completion Certification Work Phase Completion Form (WPC-V) for the Site.
In March 2020, DAA injected additional colloidal buffer (CoBupH-Mg)4, EVO product (EOS Pro)4
and nutrients (nitrogen, phosphorus, protein, and vitamin B-12)4 in the Phase 2 injection area to
optimize ongoing contaminant biodegradation. Approximately 7,000 gallons of dilute CoBupH-
Mg, 19,000 gallons of dilute EOS Pro, and 161,000 gallons of chase water were injected into the
30 existing Phase 2 injection wells over a seven -week period to distribute the buffering agent
and EVO throughout the treatment zone.
In July 2022, DAA injected colloidal buffer (CoBupH-Mg)4, EVO product (EOS Pro)4 and
bioaugmentation culture (BAC-9) supplied by EOS Remediation, LLC to stimulate reductive
dechlorination of PCE and associated daughter products around the monitoring well MW-7 via
direct push tool (DPT) between 10-30 ft bgs. Approximately a total of 1,400 gallons of dilute
CoBupH-Mg (1 part of product: 5 parts of water) , 5,400 gallons of dilute EOS Pro (1 part of
product : 5 parts of water), 8 liters of BAC-9 and 7,500 gallons of chase water were injected into
the 4 DPT locations (Figure 2) to distribute the buffering agent and EVO throughout the
treatment zone. Well construction and abandonment records for DPT points are provided in
Appendix A. The field notes and injection logs are included in Appendix B.
SIES performed the 3-month, 6-month, 9-month and 12-month, post -injection sampling events
following the completion of Phase 1 and Phase 2 injection activities. Sampling has been done
semiannually since then. In January 2022 and July 2022, DAA conducted 19th and 20th
performance monitoring assessment events, respectively, since remedial actions were
implemented. This report discusses the January and July 2022 remedial action performance
4 EOS Pro, CoBupH-Mg, nutrients and BAC-9 are provided by EOS Remediation, LLC.
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monitoring event results and includes an evaluation of remedy response. Performance
monitoring and reporting events conducted to -date are summarized in Table 1.
The following table identifies the groundwater monitoring network (20 shallow monitoring wells
and 2 compliance deep monitoring wells) for the January and July 2022 monitoring events.
January and July 2022
Performance Monitoring Network (Events 1 9th and 20th)
Phase 1 Injection Area
MW-2 and MW-16
Phase 2 Injection Area
MW-3, MW-4, MW-8 and MW-18
Shallow Compliance Wells
MW-1, MW-5, MW-7, MW-9, MW-13, MW-17, MW-19, MW-20,
MW-21, MW-22, MW-23, MW-24, MW-25, and MW-26
Deep Compliance Wells
I MW-14 and MW-15
The sampling plan was modified for the Site in July 2021 and will be implemented on future
sampling events. The primary change in the sampling program is that certain natural attenuation
parameters, MBTs and VFAs will be analyzed annually instead of semi-annually in selected
wells (see Section 2.2), since no substantial changes were observed in these parameters
historically between the sampling events. DAA submitted a notification to NCDEQ Underground
Injection Control (UIC) Program detailing the modification in the sampling plan for the Site on
April 27, 2021.
2.0 Groundwater Sampling Procedures and Results
The January 2022 and July 2022 sampling events represent the 19th and 20th groundwater
sampling events for remedial performance monitoring since completion of the initial colloidal
buffer and EVO injection activities in October 2013, the 11 th and 121h groundwater sampling
events since the July 2016 Phase 1 re -injection; the 8th and 91h groundwater sampling events
since the July 2018 MW-18 area injection; the 6th and 71h sampling events since the MW-1 area
injection in August 2019; and the 4th and 5th sampling events since the March 2020 Phase 2 re-
injection. July 2022 sampling event is the first sampling event since the completion of DPT
injection around MW-7.
2.1 Groundwater Elevations
2.1.1 Aquifer Recognition
Based on observations made from past studies and well installation, the Site is generally
underlain by an upper clay -rich overburden at the ground surface to roughly 10 to 12 ft bgs that
likely constitutes an aquitard, where intact. These surficial clay -rich deposits are underlain by
unconsolidated sands comprising the shallow aquifer that is likely semi -confined by the upper
clay -rich aquitard. Below the unconsolidated deposits is gradationally weathered saprolite to
unweathered bedrock.
Groundwater elevation data collected from monitoring and injection wells at the Site during the
pre- and post -injection sampling events support the conclusion that the shallow aquifer (sands
underlying the clay -rich overburden) is semi -confined. An unconfined aquifer, where the water
table is essentially open to changes in air pressure, will typically show little or no water -level
change in monitoring wells due to barometric pressure fluctuations because air pressure is the
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same on the water table as it is in the monitoring well bore. However, water levels measured in
monitoring wells screened in semi -confined or confined aquifers generally fluctuate from 0.2 ft to
0.5 ft within a 24-hour period due to barometric pressure changes. Water levels in Site
monitoring wells are observed to vary by 0.2 to 0.5 ft across the center (i.e., area of buildings,
appurtenances, focus of groundwater monitoring and remediation) of the property (Table 2).
2.1.2 Groundwater Elevation Data
Depth -to -water (DTW) measurements were recorded on January 18, 2022, and July 25, 2022,
in 23 shallow monitoring wells, two compliance deep monitoring wells and six piezometers for
both the January and July 2022 sampling events. (Figure 3).
Identification of monitoring wells and piezometers from which DTW data were collected for both
sampling events is provided in Table 2. The DTW measurements were collected before
groundwater purging and sample collection had begun so that groundwater extraction did not
influence DTW measurements. The DTW was measured from the established top -of -casing
measuring point on the polyvinyl chloride (PVC) well casing and the measurements were
converted to an elevation in feet above the North American Vertical Datum of 1988 (ft NAVD).
Field notes including DTW measurements are provided in Appendix C for the January and July
2022 sampling events.
A summary of DTW and calculated groundwater elevation data for the January and July 2022
sampling events, as well as past events is provided in Table 2.
2.1.3 Groundwater Potentiometric Surface and Flow Direction
The groundwater potentiometric surface and predominant groundwater flow direction from pre -
injection measurements in October 2013, and the three most recent post -injection events (July
2020, January 2021, and July 2021) are depicted in Figure 4. The January and July 2022
groundwater potentiometric surfaces are shown in Figure 5 and Figure 6, respectively.
Site topographic relief is low, and the shallow aquifer groundwater gradient is also
commensurately low (0.001-0.002 ft/ft, Figures 5 and 6). The shallow, low -relief potentiometric
surface is temporally influenced by changes in barometric pressure (discussed in Section 2.1),
local and regional precipitation amounts, and Site conditions (e.g., subsurface utilities,
impervious surfaces, etc.). Subsurface utilities (e.g., stormwater conveyances, force -main
sewer, manways) likely intercept shallow groundwater, while impervious surfaces re -direct and
concentrate stormwater infiltration. These conditions overall create complicated and ephemeral
distributions of local groundwater elevation that in turn affect hydraulic gradient and
groundwater flow direction. Bawdy Swamp, and Bawdy Swamp Creek are located to the north
and east of the Site and appear to be primary groundwater recharge zones resulting in a
generally east-southeast groundwater gradient (e.g., Figure 4).
As a result of the site conditions noted above, groundwater gradient and flow direction often
fluctuate. The predominant groundwater flow direction is usually, but not always, to the
southwest. The three recent post -injection events (January and July 2021, January 2022) show
groundwater flow is to the east-southeast, however the groundwater flow direction during the
most recent post -injection event (July 2022) was to the southwest (Figure 4 through Figure 6).
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2.2 Groundwater Sampling Procedures
Groundwater samples were collected from January 18 through January 20, 2022, and July 25
through July 27, 2022, from 20 shallow monitoring wells and two (2) deep monitoring wells
(Figure 3) in accordance with procedures referenced in the Groundwater RAP (SIES, 2013).
Each well was purged prior to sampling using a peristaltic pump. Purging continued at an
approximate rate less than or equal to the groundwater recharge rate, until the field parameters
stabilized: pH (± 0.1 standard unit [SU]), specific conductance (± 5%), and turbidity (<10
nephelometric turbidity units [NTU] or stable). Temperature, dissolved oxygen (DO), and
oxidation-reduction potential (ORP) measurements were also recorded during purging. January
2022 and July 2022 field parameter measurements and historical field data are presented in
Table 3.
Groundwater samples were collected directly into laboratory -supplied glassware, packaged,
placed on ice in coolers, and delivered via courier under chain -of -custody procedures to
Waypoint Analytical Laboratory (Waypoint, formerly Prism Laboratories, Inc) in Charlotte, NC, a
North Carolina -certified analytical laboratory, and the samples were analyzed for VOCs by
Environmental Protection Agency (EPA) Method 8260D. All samples collected in January 2022
and selected samples collected in July 2022 were also analyzed for the following natural
attenuation parameters:
• Nitrate and sulfate by EPA Method 9056A (IC 300.0);
• Ferrous iron by Method SM3500-Fe-B;
• Total iron and magnesium by EPA Method 602013;
• Methane, ethane and ethene (MEE) and acetylene by EPA Method GC-RSK
175;
• Total Organic Carbon (TOC) by SM5310C;
• Alkalinity by SM232013;
• Sulfide by Method SM4500S2-F.
Samples from a subset of six monitoring wells (MW-1, MW-2, MW-4, MW-16, MW-18 and MW-
19) were collected on the January 2022 event, only, for Molecular Biological Tools (MBTs) by
CENSUS analyses performed by Microbial Insights, Inc. in Knoxville, TN, and for volatile fatty
acids (VFAs) analyses by method AM23G performed by Pace Analytical LLC in Pittsburgh, PA.
Baseline sampling was also conducted in monitoring well MW-7 prior to the DPT injection
completed in July 2022 as discussed in Section 1.1. On July 7, 2022, MW-7 was sampled for
TOC, ferrous and total iron, magnesium, MEE, VFAs and MBTs. The groundwater sampling log
and the laboratory analytical report for baseline sampling are provided in Appendix C and
Appendix D, respectively.
2.3 Groundwater Sampling Results
The results of the field -measured parameters and laboratory analyses are discussed below.
The field parameters for the January 2022 and July 2022 events are summarized in Table 3, the
laboratory analytical data for VOCs are summarized in Table 4, the natural attenuation
parameters are summarized in Table 5, and MBT and VFA data are summarized in Table 6.
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Copies of the groundwater sampling logs are provided in Appendix C, and copies of the
laboratory analytical reports for both groundwater sampling events are provided in Appendix D.
As discussed in Section 1.0, substrate injections were conducted in two phases in 2013 and
2014:
Phase 1 injection area wells were re -injected in 2016, while MW-18 and MW-1 area
injections were conducted in 2018 and 2019, respectively;
Phase 2 injection area wells were re -injected in March 2020; and
DPT injections were completed around MW-7 in July 2022.
The locations of the Phase 1, Phase 2, MW-1 and MW-18 area injection wells and DPT injection
locations are depicted in Figure 2. The monitoring wells are grouped on the tables (except
Table 2) according to their proximity to either the Phase 1 or Phase 2 injection areas and their
location as compliance wells within the overall monitoring well network.
Water quality changes observed in the performance monitoring wells listed above result from
enhanced in -situ bioremediation due to migration of buffer, EVO, and/or bacteria from the
respective overall injection zones to the monitoring wells, and not a result of direct injection into
the monitoring wells.
2.3.1 Chlorinated Organic Compound Concentrations
PCE was detected above the laboratory method detection limit (MDL) in the following monitoring
wells (also see Table 4):
Phase 1 injection monitoring wells. PCE was detected in MW-16 at a concentration
of 0.645 pg/L in January 2022 and in MW-2 at concentration of 0.266 pg/L (this value
is above the MDL but below the reporting limit [RL] therefore considered as
estimated) in July 2022. Pre -injection concentrations of PCE in monitoring wells MW-
2 and MW-16 reduced by over 99%. As of July 2022, PCE concentration reduced
below the MDL and below the NC 2L Standard of 0.7 pg/L in MW-16 and MW-2,
respectively.
Phase 2 injection monitoring wells. PCE was detected in all wells at concentrations
ranging from 0.901 µg/L (MW-8) to 2,060 pg/L (MW-18) in January 2022, and from
6.62 µg/L (MW-8) to 902 pg/L (MW-18) in July 2022. All the detected concentrations
are above the NC 2L Standard. Pre -injection concentrations of PCE reduced by over
90% in MW-3 and by more than 99% in MW-8, although there was a slight increase
in MW-8 in July 2022. The injection in the MW-18 area reduced the PCE
concentration over 95% in MW-18; and the Phase 2 re -injections further decreased
the PCE concentrations in MW-18 and MW-4 as well.
Compliance shallow monitoring wells. PCE ranged from 0.229 pg/L (estimated, MW-
24) to 1,610 pg/L (MW-7) in January 2022 and from 0.362 pg/L (estimated, MW-25)
to 2,790 pg/L (MW-23) in July 2022. All detected concentrations are above the NC
2L Standard except MW-24 and MW-25 in January 2022, and MW-1, MW-21, MW-
24 and MW-25 in July 2022. The injection in the MW-1 area reduced the PCE
concentration about 98% in MW-1. A substantial decrease in PCE concentration was
also observed in MW-22 in January and July 2022. However, PCE concentration
increased substantially in MW-23 in July 2021 and remained elevated in both
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January and July 2022. Though PCE increased in MW-5 (99.9 µg/L) in January
2022, a significant decrease was reported in July 2022 (8.4 µg/L).
• Compliance deep monitoring wells. PCE was detected at concentrations of 0.576
pg/L and 0.440 mg/L (estimated) in MW-14 in January and July 2022 and 0.373
mg/L (estimated) in MW-15 in July 2022 which all are below the NC 2L Standard.
TCE was detected above the laboratory MDL in the following wells (see Table 4):
Phase 1 injection monitoring wells. TCE was detected in MW-16 at a concentration
of 0.645 pg/L in January 2022 which is below the NC 2L Standard of 0.7 pg/L.
Phase 2 injection monitoring wells. TCE was detected in MW-3, MW-4, MW-8 and
MW-18 at 19.4 pg/L, 446 pg/L, 1.05 µg/L and 6,900 pg/L, respectively in January
2022 and 19.5 pg/L, 243 pg/L, 6.48 µg/L and 2,210 pg/L, respectively in July 2022,
all above the NC 2L Standard of 3 pg/L except MW-8 in January 2022. TCE
Concentrations decreased compared to previous sampling events in MW-4 in both
January and July 2022 and in MW-18 in July 2022.
Compliance shallow monitoring wells. TCE was detected in all compliance shallow
monitoring wells except MW-21 and MW-24 in January and July 2022. The detected
TCE concentrations ranged from 0.86 pg/L in MW-25 to 131 pg/L in MW-7 in
January 2022 and from 0.493 pg/L (estimated) in MW-1 to 479 pg/L in MW-23 in July
2022. Concentrations exceed the NC 2L standard in nine and eight of the wells in
January 2022 and July 2022, respectively. Like PCE, a substantial decrease in TCE
concentrations was observed in MW-5 and MW-22, respectively in July 2022 and
TCE concentration increased substantially in MW-23 in July 2021 and remained
elevated in both January and July 2022.
Compliance deep monitoring wells. TCE was not detected above the MDL in either
of the compliance deep monitoring wells in any of the sampling events.
cDCE, a metabolic by-product of TCE reductive dechlorination was detected above the
laboratory MDL in the following wells (see Table 4):
Phase 1 injection monitoring wells. cDCE was detected at concentrations of 0.712
pg/L and 0.429 µg/L (estimated) in MW-2 and 3.52 pg/L and 0.419 pg/L (estimated)
in MW-16 in January 2022 and July 2022, respectively, which all are below the NC
2L Standard of 70 pg/L.
Phase 2 injection monitoring wells. cDCE was detected in all wells at concentrations
ranging from 2.02 pg/L (MW-8) to 171,000 pg/L (MW-18) in January 2022, and from
51.0 pg/L (MW-3) to 180,000 pg/L (MW-18) in July 2022. cDCE was below the NC
2L Standard of 70 pg/L in MW-8 in January 2022 and MW-3 in July 2022. All other
wells were above the NC 2L Standard. Concentration of cDCE in MW-4 increased
substantially in January and July 2022 compared to the cDCE concentration
detected in July 2021 due to the recent injections in the area (i.e., formation of
metabolic daughter product from TCE dechlorination). Concentrations also
increased in MW-8 in July 2022 compared to the previous four sampling events since
the re -injection.
Compliance shallow monitoring wells. cDCE was detected in 12 compliance shallow
monitoring wells in January 2022 and 11 wells in July 2022, with concentrations
ranging from 0.481 pg/L (estimated; MW-13) to 5,860 pg/L (MW-22) in January
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2022, and from 0.568 pg/L (MW-13) to 3,870 pg/L (MW-23) in July 2022. cDCE
concentrations exceeded the NC 2L Standard in MW-1, MW-22, MW-23 and MW-25
in January 2022, and MW-1, MW-20, MW-22 and MW-23 in July 2022. A significant
increase in cDCE concentrations was noticed in MW-20 and MW-23 in July 2022.
Compliance deep monitoring wells. cDCE was detected in MW-15 at 0.245 pg/L
(estimated) only in January 2022, which does not exceed the NC 2L standard.
VC is a metabolic by-product of cDCE and 1,1-DCE and its presence in groundwater signifies
further dechlorination of parent compounds. VC was detected above the laboratory MDL in the
following wells (see Table 4):
• Phase 1 injection monitoring wells. VC was detected in MW-2 at 1.05 and 1.07 pg/L
and in MW-16 at 3.49 pg/L and 0.407 pg/L (estimated) in January and July 2022,
respectively, which all exceed the NC 2L Standard of 0.03 pg/L.
• Phase 2 injection monitoring wells. VC was detected in MW-3, MW-4, MW-8 and
MW-18 at 4.69 pg/L, 52.0 pg/L, 1.74 µg/L and 393 pg/L, respectively in January
2022 and 3.64 pg/L, 44.4 pg/L, 1.05 µg/L and 413 pg/L, respectively in July 2022, all
above the NC 2L Standard of 0.03 pg/L. A significant increase in VC concentrations
in both MW-4 and MW-18 was noted since the last re -injection.
• Compliance shallow monitoring wells. VC was detected in 10 wells at concentrations
ranging from 0.275 pg/L (estimated, MW-9) to 23.3 µg/L (MW-20) in January 2022
and in seven wells at concentrations ranging from 0.670 pg/L (MW-26) to 59.lpg/L
(MW-20) in July 2022, which all exceed the NC 2L Standard. Significant increase in
VC concentrations were noticed in MW-20 in January and July 2022.
• Compliance deep monitoring wells. VC was not detected above the MDL in either
well in any of the 2022 sampling events.
Note: the laboratory MDL for VC is greater than the NC 2L Standard of 0.03 pg/L; therefore,
lower concentrations of VC may be present in groundwater but cannot be reliably detected by
the current laboratory method.
1,1-DCE was detected above the laboratory MDL in the following wells (also see Table 4):
• Phase 1 injection monitoring wells. 1,1-DCE was detected in MW-16 only in January
2022 at a concentration of 1.13 pg/L which was below the NC 2L Standard of 350
pg/L.
• Phase 2 injection monitoring wells. 1,1-DCE was detected in all wells in both
January 2022 and July 2022, two of which were above the NC 2L Standard during
the both sampling events, MW-4 (4,810 pg/L and 4,290 pg/L) and MW-18 (32,500
pg/L and 29,900 pg/L).
• Compliance shallow monitoring wells. 1,1-DCE was detected in 12 wells at
concentrations ranging from 1.87 pg/L (MW-20) to 1,960 µg/L (MW-22) in January
2022 and in 12 wells at concentrations ranging from 0.387 pg/L (estimated, MW-5) to
1,400 µg/L (MW-22) in July 2022. MW-22 exceeds the NC 2L Standard in both
January 2022 and July 2022, and MW-7 exceeded the NC 2L Standard only in July
2022.
• Compliance deep monitoring wells. 1,1-DCE was not detected above the MDL in
either well in any of the sampling events.
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Figure 7 compares the estimated extent of PCE concentration that exceeds the NC 2L standard
in shallow groundwater pre -injection (October 2013) and post -injection (July 2020, January
2021, and July 2021). Figure 8 and Figure 9 illustrate the estimated extent and concentration
of PCE in shallow groundwater during the January 2022 and July 2022 monitoring events,
respectively.
2.3.2 Field Measurements
Results of field -measured parameters collected during the most recent groundwater sampling
event are summarized in Table 3. The following discussion focuses primarily on these most
recent results, and where applicable presents comparisons to historic trends and relationship to
continued susceptibility to ERD biological processes for in situ bioremediation.
pH. The optimum range for biological processes, particularly related to reductive dechlorination,
is typically between pH 6 and 8 Standard Units (SU). Refer to Table 3 for January 2022 and
July 2022 measured pH in groundwater.
In Phase 1 injection monitoring wells, the January 2022 and July 2022 groundwater pH values
are consistent with previous measurements and indicate a favorable environment for ERD. For
Phase 2 injection monitoring wells, pH in MW-8 and MW-18 is comparable to the sampling
events in 2021 and still elevated, while pH in MW-3 and MW-4 is still lower than the optimum
range. It should be noted that pH in MW-3 notably increased following the completion of the re-
injection in March 2020.
The pH in compliance shallow monitoring wells remained virtually the same in all wells
compared to the previous measurements except MW-5. pH has substantially increased in MW-
5 in July 2022 and is now in the 6.0 — 6.2 range.
The January 2022 and July 2022 pH in compliance deep monitoring well MW-15 was 6.8 SU
and 6.8 SU, respectively while the pH of MW-14 was 9.5 SU and 10.8 SU, respectively. These
results are similar to pre -injection pH readings from these wells. The cause of elevated pH in
MW-14 is unknown (Table 3).
Temperature. The groundwater temperature measurements for the January 2022 event ranged
from 14.6°C (MW-24) to 18.2°C (MW-25), and for the July 2022 event ranged from 18YC (MW-
15) to 24.6°C (MW-19), with no notable difference between the shallow and deep monitoring
wells (Table 3).
ORP. Oxidation -Reduction Potential (ORP) is a measure of the electron activity of the
groundwater. Negative or near -negative ORP values indicate a reducing environment more
conducive to reductive dechlorination. The ORP measurements collected for this sampling
event showed that both Phase 1 and Phase 2 injection monitoring wells and compliance shallow
and deep monitoring wells, except MW-5, MW-7, MW-9, MW-13, MW-21, MW-24 and MW-26,
were in a reducing environment in January and July 2022. Based on ORP results, conditions
seem to be more favorable for reductive dechlorination in the injection zones (Table 3).
DO. Reductive dechlorination proceeds optimally under anaerobic conditions (USEPA, 1998);
as such, DO concentrations <0.5 milligrams per liter (mg/L) are favorable for biodegradation of
chlorinated solvents. Of the twenty-two monitoring wells sampled, thirteen of the monitoring
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wells in January 2022 and sixteen of the monitoring wells in July 2022 reported DO
concentrations equal to or less than 0.5 mg/L (Table 3).
2.3.3 Biogeochemical Laboratory Parameters
TOC and VFAs. Increases in TOC can result from the injection of organic substrate and the
migration of soluble breakdown products of the substrate away from the injections toward
monitoring wells. VFAs result from the fermentation of EVO in the substrate, in turn, providing
the hydrogen necessary for biodegradation.
One to two order -of -magnitude increases in TOC concentrations were reported within two to six
months post -injection in both Phase 1 injection monitoring wells and in two of four Phase 2
injection monitoring wells (Table 5). In addition, MW-17 and MW-20, designated as compliance
wells south of the Phase 1 injection area, showed initial increases in TOC.
In January and July 2022, TOC concentrations remained approximately the same or increased
in both Phase 1 and Phase 2 injection monitoring wells compared to the July 2021 results. TOC
concentrations in MW-4 and MW-18 remain elevated, similar to July 2021 results. There was no
discernable change in TOC concentration in any of the compliance shallow monitoring wells
except MW-19, MW-22, and MW-23. TOC levels in these wells were increased in January or
July 2022 compared to the July 2021 levels. However, some decrease was observed in TOC
concentrations in MW-19 and MW-22 in July 2022 (Table 5).
Groundwater samples from six monitoring wells (MW-1, MW-2, MW-4, MW-16, MW-18, and
MW-19) were analyzed for VFAs only in January 2022. Acetic and propionic acids make up the
largest proportion of VFAs measured in the groundwater samples. Acetic acid, formic acid and
propionic acids are the result of the fermentation of the EVO substrate. Very low levels of VFAs
were detected in the groundwater prior to injection. High concentrations of total VFAs were
observed in July 2014, two months after bioaugmentation, in Phase 1 injection monitoring wells
MW-2 and MW-16 at 1,049 mg/L and 755 mg/L, respectively. In January 2022, total VFA
concentrations remained low in both Phase 1 injection monitoring wells, increased in MW-4,
MW-18 and MW-19, and decreased in MW-1, compared to the levels recorded in July 2021
(Table 6).
Iron. Naturally occurring iron -containing minerals can be the source of ferric iron (Fe+3), which
can serve as a terminal electron acceptor for iron -reducing bacteria to metabolize both natural
and introduced organic carbon. The result is the formation of reducing conditions and the
transformation of Fe+3 to ferrous iron (Fe+2). This is evidenced by decreases in Fe+3 and
increases in Fe+2. During previous sampling events, Fe+3 decreases and Fe+2 increases
correlated to increases in TOC resulting from the presence of the organic substrate; in shallow
monitoring wells with increased TOC concentrations (MW-2, MW-8, MW-16, MW-17, MW-19
and MW-20), ferrous iron concentrations in July 2016 were at least two orders -of -magnitude
higher than baseline pre -injection concentrations in October 2013. The Fe+2 and total iron
concentrations reported during the January 2022 and July 2022 sampling events were similar
compared to the levels recorded in July 2021 in both Phase I and Phase 2 injection monitoring
wells, except for MW-3, which showed an increase in Fe+3 in July 2022. Of the shallow
compliance monitoring wells that were sampled, four wells (MW-1, MW-17, MW-19 and MW-25)
had increased in Fe+2 concentration while there was no discernable change in any of the
remaining wells (Table 5).
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Sulfate. In October 2013 and prior to initiation of injection activities, baseline water quality
sampling included groundwater sample analysis for sulfate. The data reported widespread
elevated sulfate, with nine of sixteen monitoring wells exceeding the NC 2L Standard of 250
mg/L. Sulfate was not analyzed during earlier investigation steps and the maximum
concentrations of sulfate within the various areas of the Site prior to the injections were: Phase
1 injection shallow monitoring well MW-16 at 610 mg/L; Phase 2 injection shallow monitoring
well MW-4 at 3,600 mg/L; and compliance shallow monitoring well MW-19 at 3,300 mg/L.
Overall, the highest sulfate concentrations occur on the eastern portion of the Site (Table 5).
To identify the source of the elevated sulfate, historic information from the Phase II RI Report
(SIES, 2012) was reviewed and noted that the Site is located to the west/southwest of the
former Gurley Pesticide Burial Site (Gurley Site, EPA ID: NCD986172526), a CERCLA-
regulated site. ExxonMobil Environmental Services Company is a Responsible Party for the
Gurley Site, which is currently owned by NSEW Corporation. The Gurley Site is the location of
both a former phosphate fertilizer production facility and an agricultural chemical distribution
facility. The Gurley Site includes two major areas of interest: the Pesticide Burial Area and the
Acid Plant Area. According to the Gurley Site Record of Decision (USEPA, 2006), in many
phosphate/fertilizer manufacturing plants, milled phosphate -containing rocks and sulfuric acid
were mixed in reaction vessels to produce phosphoric acid for the production of phosphate
fertilizers. The acid chambers used in the fertilizer production process were periodically
cleaned. Wash down water containing acid and soluble lead was flushed onto the ground
surface and allowed percolate downward into groundwater. The elevated sulfate (and low pH)
observed at the Eaton Selma Site is believed to be from historic activities at the Gurley Site.
During reductive dechlorination, sulfate serves as a terminal electron acceptor and thus
competes with other electron acceptors (i.e., chlorinated solvents) for introduced organic
carbon. Therefore, the presence of elevated sulfate would be expected to slow or inhibit the
bioactivity targeting the CVOCs.
Post -injection sulfate concentrations remain elevated in some monitoring wells, with
concentrations in four wells (MW-3, MW-5, MW-19, and MW-20) exceeding the NC 2L Standard
of 250 mg/L. MW-3 and MW-5 exceeded the NC 2L Standard during both January 2022 and
July 2022 sampling events, while MW-19 and MW-20 only exceeded in July 2022. This is the
first sulfate exceedance in MW-20 since December 2014. Each of these monitoring wells are
located on the eastern portion of the Site, across East Preston Street and downgradient with
respect to groundwater flow from the Gurley Site (i.e., we suspect elevated sulfate is derived
from the Gurley Site impact). Sulfate concentration substantially increased in MW-5 in January
2021 compared to the concentration reported in July 2020 and remained elevated in January
2022. MW-5 was not sampled for sulfate in July 2022 (Table 5).
Alkalinity. Alkalinity is the capacity of the aquifer to neutralize acid. CoBupH-Mg buffered
substrate (and potassium bicarbonate in addition for the injection at MW-18 area) was added at
the time of injections to increase alkalinity in the groundwater and help mitigate the Site -wide
low pH. The baseline alkalinity in shallow groundwater across the Site reported in October 2013
(before any treatment), ranged from less than the laboratory MDL of 0.59 mg/L to 50 mg/L; the
baseline alkalinity in the deeper groundwater zone ranged from 140 mg/L to 170 mg/L (Table
5).
After the Phase 1 injection in shallow monitoring wells MW-2 and MW-16, alkalinity increased by
approximately one order of magnitude and remained elevated during the subsequent
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performance monitoring period. Alkalinity in MW-3 increased following the Phase 2 re -injection
and was reported at a concentration of 58 mg/L in January 2022. However, some decrease was
observed in MW-3 during the July 2022 sampling event. There were more than two orders of
magnitude increase compared to the baseline concentrations in MW-4 and MW-18 In January
and July 2022. Alkalinity has also increased from its baseline concentration of <0.59 mg/L
(October 2013) to 190 mg/L (April 2022) following the Phase injections in MW-8 and remained
elevated during this reporting period.
A notable increase in alkalinity was initially observed in compliance shallow monitoring wells
MW-1, MW-5, MW-17, MW-20 and MW-25, which increased more than two orders of magnitude
compared to the baseline concentrations (Table 5); however, alkalinity reported in monitoring
well MW-5 during the January and July 2017 groundwater monitoring events decreased
compared to 2016 values and have since further decreased to below the MDL in January 2021.
Alkalinity levels did not notably change in any of the other compliance shallow monitoring wells
except for increases in MW-1, MW-13, and MW-23 during this reporting period. Compliance
deep monitoring wells MW-14 and MW-15 continue to have alkalinity levels around their
baseline values in January 2022.
Methane. Methanogenesis results from the anaerobic degradation of organic carbon under
strongly reducing conditions. Baseline pre -injection methane concentrations were relatively low
and ranged from 0.818 pg/L to 33.4 pg/L across the Site. In Phase 1 and Phase 2 injection
zone monitoring wells, methane concentrations increased several orders of magnitude after the
injection, with the exception of monitoring well MW-18. In January 2022 and July 2022,
methane levels remained elevated in both Phase 1 and Phase 2 injection shallow monitoring
wells except in MW-18. Methane production increased in compliance shallow monitoring wells
MW-5, MW-9, and MW-25 and remained elevated in well MW-1, MW-17, MW-19, MW-20, and
MW-23 (Table 5).
Nitrate. Nitrate can also serve as an alternate electron acceptor. Typically, in the presence of
bioavailable organic carbon, nitrate is quickly reduced and removed. Pre -injection nitrate
concentrations exceeded the NC 2L Standard of 10 mg/L in three Phase 2 injection shallow
monitoring wells (MW-3, MW-4, and MW-18) and two compliance shallow monitoring wells
(MW-5 and MW-19). During the January 2022 and July 2022 groundwater monitoring events,
nitrate levels remained low in all sampled wells and none of the sampled wells exceeded the NC
2L standard (Table 5).
Sulfide. Due to the high sulfate concentrations detected during the baseline sampling event and
the potential for hydrogen sulfide to be generated from the reduction of sulfate, in 2014 SIES
added sulfide analysis to the post -injection sampling events. Sulfide was reported above the
laboratory MDL in fifteen of eighteen monitoring wells sampled for sulfide in January 2022 and
twelve of thirteen monitoring wells in July 2022 (Table 5).
Magnesium. Laboratory analysis for magnesium was intended to serve as an indicator that the
colloidal buffer (CoBupH-Mg) was transported in groundwater to a sampled monitoring well. In
four of the six injection zone monitoring wells (MW-16 in Phase 1, and MW-3, MW-4, and MW-8
in Phase 2), the concentrations of magnesium pre -injection to post -injection are comparable,
with slight variations greater or less than the pre -injection concentration. Magnesium
concentrations increased from 0.8 mg/L (October 2013) to 24.4 mg/L (July 2022) in MW-2 and
from 80 mg/L (October 2013) to 832 mg/L (July 2022) in MW-18 (Table 5). Also, a substantial
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increase in magnesium concentration was observed in MW-5 in January and the concentration
remained elevated in MW-5. This may indicate that the buffer has not been sufficiently
distributed throughout the aquifer.
MBTs. Groundwater samples collected from shallow monitoring wells MW-1, MW-2, MW-4,
MW-16, MW-18, and MW-19 in January 2022 were enumerated for Dehalococcoides spp.
(DHC) and numbers of cells containing functional genes for dechlorination, including TCE-
reductase, VC-reductase, and BVC-A reductase. The positive identification of the
microorganisms provides evidence of the potential for biodegradation to occur, but not direct
evidence of active metabolism.
No DHC cell densities were detected above the laboratory MDL prior to injection (Table 6). Prior
to bioaugmentation, cell densities of DHC were detected above the laboratory MDL in two
Phase 1 injection monitoring wells, MW-2 and MW-16, at reported densities of 0.2 cells per
milliliter (cells/mL) and 0.3 cells/mL, respectively. The DHC densities increased several orders
of magnitude in Phase 1 injection monitoring wells MW-2 and MW-16 since the baseline
measurements and remained relatively the same (Table 6). Data collected during post -injection
sampling events have not indicated the presence of DHC population in well MW-4 except during
January 2020 (2.3E+00 cells/mL) and January 2022 (1.10E+00 cells/mL) sampling events
(Table 6). The DHC density increased some in MW-18 after the injection in the area in 2018,
though has since decreased to a concentration of 1.40E+01 cells/mL in January 2022. No
noticeable increase in DHC population compared to the baseline data was observed in MW-1
and MW-19 in January 2022.
2.4 Chlorine Number Calculation
Table 7 presents a summary of the concentrations of the CVOCs in the PCE-to-ethene
biodegradation pathway, with the calculation of the "Chlorine Number" as an indicator of the
dechlorination extent. The chlorine number accounts for the stoichiometric transformation of the
parent compounds to daughter compounds, independent of starting concentration. Thus, PCE
that was not reduced would have a chlorine number of 4.0. As daughter products become more
prevalent, the chlorine number decreases.
The January and July 2022 chlorine numbers of the six Phase 1 and Phase 2 injection
monitoring wells and four of the compliance shallow monitoring wells (MW-1, MW-17, MW-20,
MW-23 and MW-25) are listed in Table 7.
Chlorine numbers in Phase 1 injection zone monitoring wells MW-2 and MW-16 and in
compliance shallow monitoring wells MW-17 and MW-20, proximal to the Phase 1 injection
wells have decreased since the July 2016 re -injection event. However, compared to July 2021
values, chlorine number increased in MW-20 in July 2022, due to the increase in TCE, cDCE
and VC concentrations in MW-20. The chlorine number in Phase 2 injection zone monitoring
wells MW-8 and in MW-18 also decreased since the February 2014 and June 2018 injection
events, respectively. However, chlorine number increased in MW-8 in January and July 2022
compared to July 2021 value. Similarly, chlorine numbers in MW-3 and MW-4 decreased
following the re -injection in March 2020. However, chlorine number increased slightly in MW-3
in July 2022 compared to January 2022 value. Chlorine numbers in MW-1 and MW-25 also
decreased since the MW-1 area injection in June 2019, providing supporting evidence of
effective treatment for microbially-mediated dechlorination reactions (Table 7).
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2.5 Mann -Kendall Statistical Analysis
The groundwater remedy selected for areas outside of the active treatment zone is MNA. DAA
applied the Mann -Kendall statistical method to historical PCE data from compliance shallow
monitoring wells up to and including the current sampling event in July 2022. The Mann -Kendall
analysis is a non -parametric statistical procedure that analyzes trends in data over time and is
typically used to evaluate environmental monitoring data for intra-well temporal trends. The
PCE data were entered into the Mann -Kendall Toolkit software developed by GSI
Environmental Inc. (Connor et al., 2014). Statistics, i.e. a S-statistic that indicates whether a
parameter is increasing or decreasing; a Confidence Factor which indicates the degree of
confidence in the trend results; and a Coefficient of Variance which is used to distinguish
between "No Trend" and a "Stable Result" were calculated for select compliance monitoring
wells in which PCE concentrations during the January 2022 or July 2022 events exceeded the
NC 2L Standard. These included all compliance shallow monitoring wells except MW-24. MW-
1, MW-25 and MW-23 were not included in calculations due to the active treatment conducted in
the areas in June 2019 and March 2020, respectively. Statistical analysis results are provided in
Appendix E. The results of the statistical analyses, for evaluating data trends, indicated:
Probably increasing and increasing PCE concentration trends in compliance shallow
monitoring wells MW-9, MW-13, MW-21, and MW-26 at 99.3%, >99.9%, 93.6% and
99.9% confidence, respectively.
Decreasing PCE concentration trends in compliance shallow monitoring wells MW-
20 and MW-22 at 99.2% and 100% confidence, respectively.
Stable or no PCE concentration trends in compliance shallow monitoring wells MW-
5, MW-7, MW-17, and MW-19 at 87.0%, 55.9%, 50.0%, and 74.0% confidence,
respectively.
3.0 Quality Assurance/Quality Control
Field quality assurance (QA) and quality control (QC) consisted of cross -contamination source
reduction, including the use of new gloves at each monitoring well, the use of disposable
sampling equipment, and proper decontamination of non -disposable sampling equipment using
non -phosphate detergent and rinses.
As part of the laboratory QA/QC for January 2022 and July 2022 sampling events, two duplicate
samples for each sampling event and two trip blanks in January 2023 and three trip blanks in
July 2022 (one per cooler used to store/transport site -specific samples designated for aqueous
VOC analysis) were submitted for analysis of VOCs by EPA Method 8260D. The duplicate
sample results (provided in Appendix D) are within an acceptable range of values of the record
samples (MW-2 and MW-23), except that dibromochloromethane was reported in the duplicate
sample for MW-23 in July 2022 and was not detected in the original sample. No VOCs were
detected in any of the trip blanks from the January 2022 and July 2022 sampling events.
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4.0 Investigation -Derived Waste
Groundwater investigation -derived waste (IDW) generated at the Site was temporarily
containerized in a Department of Transportation approved 55-gallon metal drum. The drum was
stored at an approved location at the JCI facility. Waste was characterized according to State
requirements and handled according to State regulation based on the characterization results.
DAA coordinated with A&D Environmental, a certified waste handler, for the disposal of the
IDW. The IDW manifest for the February 2022 disposal is included as Appendix F.
5.0 Conclusions and Recommendations
The groundwater data indicate that the addition of EVO contributed to dechlorination of PCE
and TCE to daughter products cDCE and VC in the Phase 1 injection area; however complete
dechlorination of VC to non -toxic end -products ethene and ethane is still ongoing. The
laboratory analytical results and field parameters indicate that conditions for in situ
biodegradation of contaminants are more favorable since the July 2016 re -injection.
The EVO and buffer addition to the Phase 2 injection area in March 2020 demonstrated
reductions in PCE concentration in MW-4, MW-18 and MW-23. A rebound in PCE and TCE
concentrations in MW-23 was observed in July 2021; similar concentrations are observed from
both January and July 2022 monitoring events.
Implementation of in situ bioremediation has thus far been effective in reducing PCE and TCE
concentrations in much of the aquifer where the colloidal buffer and EVO were injected. This is
reflected by a progressive reduction in PCE plume extent from pre -injection compared to post -
injection (see Figure 7, Figure 8, and Figure 9. Graphs depicting CVOC concentrations over
time in select monitoring wells are included in Appendix G, and typically show decreases in
CVOC concentrations in most wells.
Bioremediation appears to effectively reduce CVOC concentrations in the Phase 1 injection
area. The organic substrate and pH buffer injections appear to favorably affect the Phase 2
injection area.
The results of MW-18 area injection indicate notable reductions in PCE and TCE concentrations
in MW-18. The March 2020 Phase 2 re -injection further enhanced the reduction in PCE
concentration as observed during the January and July 2022 monitoring events. MW-18 still
maintains elevated cDCE concentrations through July 2022 and VC concentrations increased
substantially in January and July 2022. Its presence supports the further dechlorination of
parent compounds. However, ethene concentration decreased in July 2022.
Additional injection activities near MW-1 decreased the CVOC concentrations in MW-1 and
MW-25 and production of ethene was observed in MW-25 in January and July 2022 (Tables 4
and 5). Remedial action groundwater performance monitoring will be continued at the Site.
Regarding the DPT injection around MW-7, the results of the groundwater samples collected
from MW-7 during the July 2022 sampling event indicated no significant reduction of CVOC
concentrations in MW-7 which shows that DPT injection has not affected the MW-7 area yet.
Contaminant concentrations in compliance monitoring wells located beyond the injection zone
remain relatively stable or decrease compared to historic sampling events, with the exceptions
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of MW-9 and MW-13, which appear to be trending gradually upward for the past several years.
Eaton will evaluate if injections near MW-13 are warranted. Also, PCE was detected in
compliance boundary monitoring wells MW-21 and MW-26 in January and July 2022,
demonstrating through Mann -Kendall analyses a probably increasing trend, and increasing
trend, respectively.
TRC will continue to monitor contaminant concentrations and bioremediation progress in both
Phase 1 and Phase 2 injection area monitoring wells and all compliance shallow and deep
monitoring wells. The next sampling events are scheduled for January 2023 and July 2023. The
results of these sampling events will be submitted with the next annual project status update
report in February 2024.
6.0 References
Connor, J. A., S.K. Farhat, and M. Vanderford, 2014. GSI Mann -Kendall Toolkit for Quantitative
Analysis of Plume Concentration Trends. Groundwater. Doi: 10.1111/gwat.12277.
SIES, 2012. Phase 11 Remedial Investigation Report, Former Eaton Corporation Facility, 1100
East Preston Street, Selma, Johnston County, February 8.
SIES, 2013a. Remedial Action Plan for Groundwater, Former Eaton Corporation Facility, 1100
East Preston Street, Selma, Johnston County, North Carolina, June 3.
SIES, 2013b. Pre -Construction Report, Former Eaton Corporation Facility, 1100 East Preston
Street, Selma, Johnston County, North Carolina, September 16.
SIES, 2016. Groundwater Remedial Action Plan Supplement, Former Eaton Corporation
Facility, 1100 East Preston Street, Selma, Johnston County, North Carolina, April 21.
SIES, 2017. 9t" Groundwater Remedial Action Performance Monitoring Report, Former Eaton
Corporation Facility, 1100 East Preston Street, Selma, Johnston County, North Carolina,
October 11.
SIES, 2018. 10t" Groundwater Remedial Action Performance Monitoring Report, Former Eaton
Corporation Facility, 1100 East Preston Street, Selma, Johnston County, North Carolina, March
27.
USEPA, 1998. Technical Protocol for Evaluating Natural Attenuation of Chlorinated Solvents in
Ground Water, USEPA Office of Research and Development, EPA/600/R-98/128, September
1998.
USEPA, 2006. Record of Decision, Gurley Pesticide Burial Site, EPA ID: NCD986172526, OU
01, Selma, NC, September 28.
Annual Project Status Update Report
Former Eaton Corporation Facility, Selma, North Carolina November 15, 2022
DAA Project No. 017025.0000.0000 17

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SELMA, INC. 2013
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SCALE IN FEET
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FORMER EATON FACILITY
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<� DATE: 9/1/2022
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version: 2017-10-21

LEGEND
SHALLOW MONITORING
WATER LINE
0
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SEWER LINE
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TELEPHONE LINE
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PHASE 2 INJECTION
WELL
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�
PROPERTY BOUNDARY
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W 79
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' 'W-88
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I I
V-77
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PROJECT:
<i T;zc
114 Edinburgh South Drive, Suite 200
TITLE.
Cary, NC 27587
Phone: [phone]
www.tresolutions.com
FORMER
EATON
FACILITY
FORMER EATON FACILITY
100 EAST PRESTON STREET
SELMA, JOHNSTON COUNTY, NC
INJECTION WELL LAYOUT
c
H E E
£ �IW-51
yl
£ �M W-9
£ c * W-52
I
I IW-53
— ss — SS — SS — ss SS — SS IS
WE +IW-54
j I — w —�
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w �' 1 W-55* +11 1-56 I
I W-57 £
— Ss — SS — SS — SS — SS — ss1�/-5 g
W E
IW-59 MW-3� 1W_61
W
DRAWN BY:
KStark
CHECKED BY:
BYuncu
APPROVED BY:
BYuncu
DATE:
9/1 /2022
PROJ. NO.:
017025
FILE:
2023 Annual Progress Report.dwg
2
Version: 2017-10 21