B.08 GFI JB CHS PBR TU939 (AOC B-3) Draft Semi-Annual Progress Report 5.pdf

DRAFT

Semi-Annual Progress Report 5

Area of Concern B-3 (TU939 and LUST ID 01075) Former Building 7 – Heat Plant

PERFORMANCE-BASED REMEDIATION

Joint Base Charleston Weapons

SOUTH CAROLINA

Contract FA8903-15-C-0016 November 2022

Revision 00

Prepared for:

AFCEC/CZRE

US Air Force Civil Engineer Center

772nd ESS/PKS 2261 Hughes Avenue, Suite 155 JBSA Lackland, TX 78236-9853

Prepared by:

AECOM

4016 Salt Pointe Parkway

Charleston, South Carolina 29405

With Teaming Partners:

TU939 (AOC B-3)

Joint Base Charleston Weapons, South Carolina

Contract FA8903-15-C-0016 i BWJ140078

DOCUMENT CERTIFICATION

I certify under penalty of law that this document and all attachments were prepared under my direction or supervision in accordance with a system designed to assure that qualified personnel properly gather and evaluate the information submitted. Based on my inquiry of the person or persons who manage the system, or those persons directly responsible for gathering the information, the information submitted is, to the best of my knowledge and belief, true, accurate, and complete. I am aware that there are significant penalties for submitting false information, including the possibility of fine and imprisonment for knowing violations. This document is signed and certified in accordance with R.61-79.270.11 and 270.30(K).

______________________________ 22 November 2022

Megan DuMont, P.E. Date

Registration Number 32490

Joint Base Charleston Weapons, South Carolina

Contract FA8903-15-C-0016 ii BWJ140078

Table of Contents

TABLE OF CONTENTS ........................................................................................................... ii ACRONYMS AND ABBREVIATIONS ..................................................................................... iv

1.0 INTRODUCTION ......................................................................................................... 1-1

1.1 Site Description ..........................................................................................................1-1

1.2 Site Assessment History ............................................................................................1-1

1.3 Geologic Setting ........................................................................................................1-3

2.0 GROUNDWATER REMEDIATION ACTIVITIES ......................................................... 2-1

2.1 Injection Activities ......................................................................................................2-1

2.2 Performance Monitoring .............................................................................................2-2

3.0 ANNUAL PERFORMANCE MONITORING ACTIVITIES ............................................ 3-1

3.1 Field Activities ............................................................................................................3-1

3.1.1 Groundwater Level Measurements .................................................................... 3-1

3.1.2 Groundwater Monitoring Well Purging ............................................................... 3-1

3.1.3 Groundwater Sampling ...................................................................................... 3-1

3.1.4 Quality Assurance and Quality Control Samples ................................................ 3-2

3.2 Data Evaluation and Usability ....................................................................................3-2

3.3 Investigation-Derived Waste ......................................................................................3-2

4.0 QUARTERLY PERFORMANCE MONITORING ACTIVITIES ..................................... 4-1

4.1 Field Activities ............................................................................................................4-1

4.1.1 Groundwater Level Measurements .................................................................... 4-1

4.1.2 Groundwater Monitoring Well Purging ............................................................... 4-1

4.1.3 Groundwater Sampling ...................................................................................... 4-1

4.1.4 Quality Assurance and Quality Control Samples ................................................ 4-2

4.2 Data Evaluation and Usability ....................................................................................4-2

4.3 Investigation-Derived Waste ......................................................................................4-2

5.0 GROUNDWATER FLOW AND CONTAMINANT DISTRIBUTION .............................. 5-1

5.1 Groundwater Elevations .............................................................................................5-1

5.2 Contaminant Distribution ............................................................................................5-1

6.0 CONCLUSIONS AND RECOMMENDATIONS ........................................................... 6-1

6.1 Conclusions ...............................................................................................................6-1

6.2 Recommendations .....................................................................................................6-1

7.0 REFERENCES ............................................................................................................ 7-1

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Contract FA8903-15-C-0016 iii BWJ140078

Tables Table 3-1 Groundwater Elevation Data – August 2022 Table 3-2 Summary of Groundwater Parameters – August 2022 Table 3-3 Groundwater Analytical Results – August 2022 Table 4-1 Groundwater Elevation Data – October 2022 Table 4-2 Summary of Groundwater Parameters – October 2022 Table 4-3 Groundwater Analytical Results – October 2022 Table 5-1 Summary of Historical Analytical Results in Groundwater

Figures Figure 1-1 Joint Base Charleston Weapons Location Map Figure 1-2 AOC B-3 Former Building 7 Site Location Map Figure 1-3 AOC B-3 Former Building 7 Site Layout Map Figure 2-1 AOC B-3 Former Building 7 Injection Point Layout Figure 3-1 AOC B-3 Former Building 7 Potentiometric Surface Map (August 2022) Figure 3-2 AOC B-3 Former Building 7 Distribution of Volatile Organic Compound

Detections (August 2022) Figure 4-1 AOC B-3 Former Building 7 Potentiometric Surface Map (October 2022) Figure 4-2 AOC B-3 Former Building 7 Distribution of Volatile Organic Compound

Detections (October 2022)

Appendices Appendix A SCDHEC Correspondence Appendix B Field Forms Appendix C SCDHEC 1903 Forms Appendix D AST Injection Report Appendix E Laboratory Analytical Reports Appendix F Data Validation Reports Appendix G Waste Disposal Documentation Appendix H Time Trend Plots

Joint Base Charleston Weapons, South Carolina

Contract FA8903-15-C-0016 iv BWJ140078

ACRONYMS AND ABBREVIATIONS

µg/L.......... microgram per liter ACQAP .... annual contractor quality assurance plan AECOM.... AECOM Technical Services, Inc.

AFCEC .... Air Force Civil Engineer Center AFVR ....... aggressive fluid vapor recovery amsl ......... above mean sea level AOC ......... area of concern AST .......... AST Environmental bgs ........... below ground surface CAP ......... corrective action plan CNFA ....... conditional no further action COC ....... constituent of concern DO ........... dissolved oxygen DoD ......... Department of Defense DPT ......... direct push technology ELAP ....... Environmental Laboratory

Accreditation Program ft .............. feet GE&E ....... General Engineering &

Environmental, LLC HA ............ hydrogeologic assessment ID ............. identification IDW .......... investigation-derived waste JBC .......... Joint Base Charleston LCS .......... laboratory control sample LCSD ....... laboratory control sample duplicate LUST ....... leaking underground storage tank

MNA ......... monitored natural attenuation MS……… matrix spike MSD……. matrix spike duplicate NTU ..... nephelometric turbidity unit ORC-A® .. Oxygen Release Compound

Advanced®

ORP ..... oxidation reduction potential PACE ....... Pace Analytical Services, LLC PPE .......... personal protective equipment psi ..... pounds per square inch QAPP ..... quality assurance project plan RBCA ....... risk-based corrective action RBSL ....... risk-based screening level RCRA ....... Resource Conservation and

Recovery Act RPD ......... relative percent difference RPI ........... Remedial Products, Inc.

SCDHEC.. South Carolina Department of

Health and Environmental Control

SSTL ........ site-specific target level SSWP ...... site specific work plan SU ............ standard units UIC ........... underground injection control USEPA ..... United States Environmental

Protection Agency UST ........ underground storage tank

Joint Base Charleston Weapons, South Carolina

Contract FA8903-15-C-0016 1-1 BWJ140078

1.0 INTRODUCTION

AECOM Technical Services, Inc. (AECOM) has prepared this Semi-Annual Progress Report 4 under Contract No. FA8903-15-C-0016, for the United States Air Force Civil Engineer Center (AFCEC) at Joint Base San Antonio-Lackland, Texas. This report presents the results of field activities and laboratory analyses from January and April 2021 for TU939, Leaking Underground Storage Tank (LUST) Identification (ID) 01075 (former Building 7) at Joint Base Charleston (JBC) Weapons located in Goose Creek, South Carolina (Figure 1-1). This non-regulated underground storage tank (UST) site is managed by the Department of Defense (DoD) Corrective Action Section of the South Carolina Department of Health and Environmental Control (SCDHEC) Division of Waste Management. The site is identified as Area of Concern (AOC) B-3 in the Resource Conservation and Recovery Act (RCRA) Part B Operating Permit for JBC Weapons (SC8170022620). The technical approach is based on the Corrective Action Plan (CAP) Addendum for TU939 and LUST ID 01075, Former Building 7 (AECOM, 2022a). The sampling plan was also detailed in the Corrective Action Plan (CAP) for TU939 and LUST ID 01075, Former Building 7 (AECOM, 2018) and the Annual Contractor Quality Assurance Plan (AECOM, 2022b).

The CAP Addendum for AOC B-2 was approved by SCDHEC in a letter provided in Appendix A.

This JBC Weapons site is monitored in accordance with the SCDHEC UST program guidelines and regulations. Sampling and reporting activities have been conducted in accordance with the SCDHEC UST Programmatic Quality Assurance Project Plan (QAPP), Revision 4.0 (SCDHEC, 2020), hereinafter referred to as the UST Programmatic QAPP. The purpose of this report is to document quarterly groundwater monitoring results following remedial activities conducted at

AOC B-3.

1.1 Site Description

Former Building 7 (AOC B-3), the former Heat Plant, was located on the south side of JBC Weapons (Figure 1-2) and was demolished in 2004. The building contained a boiler and associated 4,000-gallon, steel UST. The UST was installed in the 1960s and closed through excavation in 1998. Based upon the results of further investigation at the site in 2002 (General Engineering & Environmental, LLC [GE&E], 2002), petroleum impacts to soil and groundwater were identified that exceeded SCDHEC Risk-Based Screening Levels (RBSLs) (GE&E, 2002).

1.2 Site Assessment History

Petroleum odors and soil staining were noted during the closure activities involving the excavation and removal of the UST. Additionally, evidence of free-phase petroleum was noted within the excavation. Soil samples were collected and analyzed for polycyclic aromatic hydrocarbons;

benzene, toluene, ethylbenzene, and total xylenes; and total petroleum hydrocarbons. Soil sampling results indicated the presence of petroleum constituents (GE&E, 2002).

Based upon the results of the tank closure assessment, a Hydrogeologic Assessment (HA) was performed in 2002 by GE&E to assess the extent and severity of the impacted soil and groundwater. Seven soil borings were installed within the vicinity of the former UST. Constituents of concern (COCs) were detected above the RBSLs, resulting in the need for plume delineation.

Eleven discrete groundwater samples were collected using direct push technology to delineate the zero-impact boundary. These samples were analyzed by an onsite mobile laboratory. Based on the results of the groundwater samples, seven permanent monitoring wells were installed. The results of the samples from the permanent wells also indicated COC concentrations above SCDHEC RBSLs. Slug tests were performed during this assessment to evaluate the aquifer.

GE&E recommended routine monitoring to gauge potential plume migration and monitor potential biodegradation (GE&E, 2002).

Joint Base Charleston Weapons, South Carolina

Contract FA8903-15-C-0016 1-2 BWJ140078

The HA included a risk-based corrective action (RBCA) evaluation to determine risk to human health and the environment from petroleum constituents present in soil and groundwater. The RBCA evaluation consisted of Tier 1 and Tier 2 evaluations in accordance with guidelines presented in SCDHEC’s Risk-Based Corrective Action for Petroleum Releases (SCDHEC, 2016).

The Tier 1 evaluation consisted of a comparison of soil and groundwater results obtained during the assessment to established RBSLs from the referenced guidance document. The Tier 2 evaluation included soil and groundwater sampling, aquifer testing, and receptor identification.

The only sensitive receptors identified in the vicinity of Former Building 7 were a water line and a communications line. Site-Specific Target Levels (SSTLs) were established for each constituent of concern above its respective RBSL using the RBCA tool kit from the referenced guidance document (SCDHEC, 2016).

The SSTLs for constituents of concern in groundwater sampling obtained during the HA (GE&E, 2002) and established by SCDHEC as of April 20, 2000, are listed below:

Constituent of Concern SSTL Unit

Benzene 1,800 µg/L

Naphthalene 31 µg/L µg/L-microgram per liter SSTL – site-specific target level

These screening criteria can be used to obtain Conditional No Further Action (CNFA) but would not achieve Site Closure.

Based on the results of the HA, routine groundwater monitoring was approved by SCDHEC in a letter to the Naval Weapons Station dated July 15, 2002. The locations of the Former Building 7 monitoring wells are shown in Figure 1-3. The Former Building 922 (TU929, nearby UST site) wells are also included in Figure 1-3 for reference purposes. Quarterly sampling was conducted at the site in 2003; semi-annual sampling was conducted from 2004 through 2006; and annual sampling has been conducted since 2007. The site is currently monitored for benzene and naphthalene. Sporadic occurrences of free product have been detected at the site, primarily in MW-1, MW-2, and MW-5. Monitored natural attenuation (MNA) was documented at the site through a study that began in 2003 and was suspended in 2015, as MNA was effectively demonstrated. Benzene and naphthalene have been consistently detected above RBSLs in several wells during annual groundwater monitoring events. Various aggressive fluid vapor recovery (AFVR) events have been conducted at the site and were last employed in 2006. Free product, as it occurs, is presently addressed using hydrophobic socks (AECOM, 2016).

In the 2016 annual groundwater monitoring report (AECOM, 2016), the following recommendations were made:

• Discontinue monitoring of ethylbenzene, toluene, methyl tert-butyl ether, and total xylenes since there have been no exceedances of these constituents since January 2002; and

• Continue annual sampling of nine monitoring wells MW-1, MW-2, MW-3, MW-4, MW-5, MW-6, MW-7, MW-8, and MW-9 for benzene and naphthalene only and collection of field parameters.

SCDHEC approved these recommendations in a letter dated December 14, 2016 (Appendix A).

A CAP was completed in 2018 proposing excavation of impacted soils and injection of Oxygen Release Compound Advanced® (ORC-A®) at the site (AECOM, 2018). This document was approved in a letter dated March 2, 2018 (Appendix A). Following soil excavation and injection of ORC-A® in 2018, quarterly performance monitoring was recommended at select wells in addition to annual monitoring to evaluate the remedial actions (AECOM, 2019). MW-2 and MW-

Joint Base Charleston Weapons, South Carolina

Contract FA8903-15-C-0016 1-3 BWJ140078

5 were removed during excavation and replaced with MW-2-R and MW-5-R. ORC-A® is an oxygen release compound designed specifically for enhanced, in situ aerobic bioremediation of petroleum hydrocarbons in groundwater and saturated soils. Quarterly performance monitoring was conducted from 2019 to April 2021 at seven monitoring wells (MW-1, MW-2-R, MW-3, MW-4, MW-5-R, MW-7, and MW-9) following remediation. Quarterly monitoring was suspended following the April 2021 sampling event due to the failure to achieve the reduction of contaminant concentrations below screening levels in groundwater. A CAP Addendum was submitted to SCDHEC in January 2022 proposing supplemental injections using a carbon trap and treat product called BOS-200. Following the injections of BOS-200 quarterly performance monitoring will resume as outlined in the CAP Addendum (AECOM, 2022).

1.3 Geologic Setting

The site is located in the Lower Coastal Plain Physiographic Province. The Lower Coastal Plain is a wedge of unconsolidated and lithified sediments overlying a basement complex of igneous and metamorphic rocks. The total thickness of coastal plain sediments underlying the site is approximately 2,500 feet (ft). The geologic materials beneath the site indicate that the unconsolidated sediments belong to the Pamlico Formation. These unconsolidated sediments are approximately 28 to 30 ft thick and overlie the Cooper Group sediments, which are comprised of the older Ashley, Parkers Ferry, and Harleyville Formations. The Cooper Group is a sequence of homogeneous, clay-rich, phosphatic limestones and sandy calcareous silts, which underlie most of the coastal counties of South Carolina, south of the Santee River.

Near the site, the Cooper Group sediments are approximately 280 ft thick. The Cooper Group sediments exhibit low permeability, which limits the migration of groundwater between aquifers located above and below the Cooper Group. Due to this low permeability, Cooper Group formations are considered to be a significant regional aquitard. Groundwater was encountered between approximately 25 and 29 ft above mean sea level (amsl) as recorded during the sampling events.

Joint Base Charleston Weapons, South Carolina

Contract FA8903-15-C-0016 2-1 BWJ140078

2.0 GROUNDWATER REMEDIATION ACTIVITIES

Supplemental injections of BOS 200® at AOC B-3 were approved as part of the CAP Addendum (Appendix A). Underground Injection Control (UIC) Permits to construct and operate 20 direct push technology (DPT) Class VA-I wells at AOC B-2 were obtained from SCDHEC on February 17, 2022, and February 18, 2022, respectively (Appendix A). On June 22 and June 23, 2022, AST Environmental (AST) injected BOS-200® into the 16 pre-determined injection DPT locations.

BOS 200® is a proprietary remedial technology developed by Remedial Products, Inc. (RPI).

According to RPI:

BOS 200® is a Trap & Treat® in situ remediation technology specifically designed to degrade petroleum hydrocarbons, related solvents, and oils. BOS 200® is a complete system effecting accelerated biodegradation of various organic compounds on an activated carbon platform that includes micro and macro nutrients, time release terminal electron acceptors, and a blend of facultative organisms designed to flourish within the aerobic to anaerobic conditions present in the pore structure of the carbon. It has been demonstrated to be effective with light non-aqueous phase liquid, fuel oxygenates, alcohols, glycols, and cyclic ethers. No toxic byproducts such as sulfide are produced. The product is insensitive to groundwater geochemistry and is effective under aerobic and anaerobic conditions and over a broad range of pH. High salinity and TDS of 30,000 ppm are also not detrimental to performance (RPI, 2021).

Groundwater contaminants such as naphthalene quickly sorb onto the carbon substrate which are colonized by contaminant-degrading microbes. Based upon contaminant concentrations decreasing over time and previously documented concentrations of monitored natural attenuation parameters, it appears that biodegradation is already occurring. BOS 200® is anticipated to enhance the biodegradation of contaminants. The objective of injecting this solution is to capture the dissolved phase petroleum hydrocarbons (benzene and naphthalene) and stimulate biological activity to remediate contaminated groundwater thereby achieving NFA status.

2.1 Injection Activities

The remedial approach in the approved work plan included injection of approximately 1,100 pounds of BOS 200® creating approximately 1,100 gallons of slurry into the 20 DPT points.

However, due to the presence of water, sewer, and communication lines in the subsurface at the site, the total number of injection points was reduced from 20 to 10 in the field. The concentration of BOS 200® injected at the remaining 10 injection locations was increased to compensate. This resulted in 1,100 pounds of BOS 200® creating 771 gallons of slurry injected into 10 injection points. The substrate was mixed with tap water from a nearby fire hydrant. The injection intervals were staggered between 5 and 15 ft below ground surface (bgs) and 4 and 14 ft bgs. The SCDHEC 1903 forms for the injection points are included in Appendix C. The injection points were spaced on 5 ft centers, except in the areas where utilities were present. Spacing was adjusted to allow for safe clearance of the utilities. The final injection locations are presented on Figure 2-1.

The volume of substrate injected into each injection well was tracked using totalizers. These volumes and additional injection data are presented in Appendix D. Once approximately 77 gallons had been injected into each injection point, the injection hose was disconnected from the DPT point and the injection operation was then moved to the next DPT point. Significant daylighting of injection slurry was observed at IP-9, IP-4, IP-8, and IP-2. Injection pressure and flow rate were monitored continuously. The injection rates for the injection wells ranged from 2 - 30 gallons per minute and the injection pressure for the injection wells ranged from 20-500 pounds per square inch (psi). Injection pressures observed in the field did not exceed the proposed

Joint Base Charleston Weapons, South Carolina

Contract FA8903-15-C-0016 2-2 BWJ140078 maximum pressure of 500 psi. Daylighting was likely due to preferential pathways created by previous injections, utilities, and excavations in the small footprint of the site.

A photo log of the AOC B-3 groundwater remediation activities and field documentation from the injection is presented in Appendix D.

2.2 Performance Monitoring

Annual groundwater monitoring at the site was conducted in April 2021 and serves as baseline data for monitoring the effectiveness of the injection. The injection of BOS 200® solution was followed by a site wide groundwater sampling event in August 2022 and included all nine wells in the current annual sampling plan (See Section 3 for results). The first of three quarterly performance groundwater monitoring events was completed in October 2022 (See Section 4 for results). During the quarterly post injection events, groundwater samples were only collected from two monitoring wells (MW-1 and MW-2-R). The goal of the quarterly monitoring program was to assess the performance of the BOS 200® injection and evaluate remediation progress.

Groundwater samples will be collected using a peristaltic pump. New Teflon® tubing was used to eliminate the potential for cross-contamination. Low-flow purging and sampling methods were utilized at the site in accordance with the 2022 AECOM Annual Contractor Quality Assurance Plan (ACQAP; AECOM, 2022) and UST Programmatic QAPP. Groundwater samples collected were submitted to a State of South Carolina certified laboratory and analyzed for benzene and naphthalene.

Groundwater samples collected during the annual and quarterly monitoring events are intended to evaluate the groundwater remedy performance and will be analyzed for naphthalene utilizing United States Environmental Protection Agency (USEPA) Method 8260B. Additionally, water quality parameters (pH, temperature, turbidity, specific conductivity, dissolved oxygen [DO], and oxidation-reduction potential [ORP]) were measured in the field and recorded during all well purging activities. The results of the annual and first quarterly monitoring events are presented in this Annual Groundwater Monitoring Report.

Joint Base Charleston Weapons, South Carolina

Contract FA8903-15-C-0016 3-1 BWJ140078

3.0 ANNUAL PERFORMANCE MONITORING ACTIVITIES

The following presents a summary of the site wide groundwater sampling activities completed following injection. This sampling event was conducted in August 2022.

3.1 Field Activities

Performance monitoring field activities were conducted on August 1, 2022 and included the collection of depth to groundwater level measurements from all nine site monitoring wells, thickness of free product (if encountered), and collection of groundwater samples from all nine monitoring wells. Field activities were conducted in accordance with procedures summarized in the UST Programmatic QAPP and the Uniform Federal Policy – Quality Assurance Project Plan for Basewide Groundwater, Surface Water, and Land Use Control Monitoring (Bay West, 2016a).

3.1.1 Groundwater Level Measurements

Prior to initiation of monitoring well purging and groundwater sampling, a complete round of groundwater level measurements was collected from the nine monitoring wells. Measurements were made using an oil-water interface probe and were measured from the marked survey point, if available, on the top of the monitoring well casing. The interface probe was decontaminated between each monitoring well. Each monitoring well was opened and allowed to equilibrate to atmospheric pressure before collection of the water level measurement. Groundwater measurements, including calculated groundwater elevations, are summarized in Table 3-1. A potentiometric surface map based on these data is presented on Figure 3-1. No free product was encountered during this monitoring event.

3.1.2 Groundwater Monitoring Well Purging

Low-flow purging/sample collection techniques were employed, and a peristaltic pump was used to purge/sample each of the monitoring wells (SCDHEC, 2020). Disposable sample tubing (Teflon® lined) was lowered into a given monitoring well and positioned below the top of the water column from the approximate middle to the uppermost portion of the well screen, depending on well recovery rates during purging. The pumping rate was adjusted to minimize drawdown. The pumps were operated continuously during sampling to minimize aeration in the tubing.

Groundwater quality parameters including pH, specific conductance, turbidity, DO, temperature, and ORP were monitored during purging and were recorded on the groundwater sampling log for each monitoring well and are provided in Appendix B. Purging continued until the temperature, pH, and specific conductance had stabilized and the turbidity had either stabilized or was below 10 nephelometric turbidity units (NTU). In accordance with the UST Programmatic QAPP (SCDHEC, 2020), stabilization was considered complete when pH measurements remained constant within 0.1 Standard Unit (SU), or reproducible to within 0.1 SU, specific conductance varied no more than 10 percent, and the temperature was constant for at least three consecutive readings. A summary of field parameters collected during well purging is presented in Table 3-2.

3.1.3 Groundwater Sampling

Following the purging activities, groundwater samples were collected from each of the nine monitoring wells following procedures established in the UST Programmatic QAPP (SCDHEC, 2020). Groundwater samples were analyzed for the following constituents by Pace Analytical Services, LLC (Pace, formerly Shealy Environmental Services, Inc.). Pace currently holds a DoD Environmental Laboratory Accreditation Program (ELAP) certification and the SCDHEC Certification number is 32010001

• Benzene and naphthalene by USEPA Method 8260B

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Contract FA8903-15-C-0016 3-2 BWJ140078

Analyses conformed to USEPA methodology described in Test Methods for Evaluating Solid Waste, Physical/Chemical Methods (USEPA, 2007) and in the UST Programmatic QAPP (SCDHEC, 2020). Laboratory analytical results are present in Table 3-3 and analyte concentrations in excess of their respective RBSLs are depicted on Figure 3-2. The field duplicate sample is included in Table 3-3 along with the laboratory analytical results for the primary groundwater samples. A laboratory-prepared trip blank , field blank, and equipment blank were also included with sample shipments to the laboratory. The laboratory analytical report with chain of custody documentation is provided in Appendix E.

3.1.4 Quality Assurance and Quality Control Samples

Field quality control samples were collected to assure that data were of suitable quality to be used in the sampling program. The following Quality Assurance and Quality Control samples were collected:

• One field duplicate sample (01075-MW-2-R-BLDG-7-FD);

• One matrix spike/matrix spike duplicate (MS/MSD) set (01075-MW-1-BLDG-7-MS/ 01075-

MW-1-BLDG-7-MSD);

• One equipment blank (01075-EB-BLDG-7);

• One field blank (01075-FB-BLDG-7); and

• One trip blank (01075-TB-BLDG-7).

3.2 Data Evaluation and Usability

One hundred percent of the analytical data were reviewed based on USEPA National Functional Guidelines for Organic Superfund Methods Data Review (USEPA, 2017), DoD Consolidated Quality Systems Manual for Environmental Laboratories, version 5.3 (DoD, 2019), and the Uniform Federal Policy – Quality Assurance Project Plan for Performance-Based Remediation, Basewide Groundwater, Surface Water, and Land Use Control Monitoring (Bay West, 2016). The data validation process included review of chains-of-custody, sample condition receipt forms, field duplicate sample relative percent differences (RPDs), surrogate recoveries, equipment/method/trip blanks, laboratory control sample/laboratory control sample duplicate (LCS/LCSD) recoveries and RPDs, and MS/MSD RPDs. Data was evaluated to verify the achievement of precision, accuracy, representativeness, completeness, comparability, and sensitivity goals established to meet the project data quality objectives.

Results of the evaluation suggest representative samples were collected and analyzed, and the results are representative of the media analyzed. Data qualifiers were added to the data as a result of the validation process (high surrogate recovery). The samples qualified and overall quality of the data collected is discussed in the Data Validation Report provided in Appendix F.

The data reflect expected site conditions and should be considered compliant and adequate for their intended purpose.

3.3 Investigation-Derived Waste

Liquid Investigation derived waste (IDW) generated during the August 2022 field sampling activities consisted of monitoring well purge and development water. Purge water was pumped into 5-gallon graduated buckets during purging and sampling procedures then transferred into a 55-gallon steel drum. One drum was generated during the groundwater sampling. The 55-gallon drum was labeled with proper identifying and contact information, including source location, contents, and date collected. Drums are stored on JBC Weapons property, within the Hazardous Waste Storage Area. Used personal protective equipment, primarily nitrile gloves and sample tubing, was consolidated into trash bags and placed into a dumpster behind Building 2 at JBC

Joint Base Charleston Weapons, South Carolina

Contract FA8903-15-C-0016 3-3 BWJ140078

Weapons for disposal as non-hazardous waste at a Subtitle D Solid Waste Landfill, in accordance with the Uniform Federal Policy – Quality Assurance Project Plan for Basewide Soil Sampling and Analysis (Bay West, 2016b).

The final manifest for disposal will be included in Appendix G in the Draft Final version of this document.

Joint Base Charleston Weapons, South Carolina

Contract FA8903-15-C-0016 4-1 BWJ140078

4.0 QUARTERLY PERFORMANCE MONITORING ACTIVITIES

The following presents a summary of second quarterly performance monitoring activities following injection. This sampling event was conducted in October 2022.

4.1 Field Activities

Field activities were conducted on October 7, 2022 and included the collection of depth to groundwater level measurements, thickness of free product (if encountered), and collection of groundwater samples from two monitoring wells. Field activities were conducted in accordance with procedures summarized in the UST Programmatic QAPP and the Uniform Federal Policy – Quality Assurance Project Plan for Performance-Based Remediation, Basewide Groundwater, Surface Water, and Land Use Control Monitoring (Bay West, 2016a).

4.1.1 Groundwater Level Measurements

Prior to initiation of monitoring well purging and groundwater sampling, a complete round of groundwater level measurements was collected from the 9 site monitoring wells. Measurements were made using an oil-water interface probe and were measured from the marked survey point, if available, on the top of the monitoring well casing. Each monitoring well was opened and allowed to equilibrate to atmospheric pressure before collection of the water level measurement.

Groundwater measurements, including calculated groundwater elevations, are summarized in Table 4-1. A potentiometric surface map based on these data is presented on Figure 4-1. No free product was encountered during this monitoring event (Appendix B).

4.1.2 Groundwater Monitoring Well Purging

Low-flow purging/sample collection techniques were employed, and a peristaltic pump was used to purge/sample each of the monitoring wells (SCDHEC, 2020). Disposable sample tubing (Teflon® lined) was lowered into a given monitoring well and positioned below the top of the water column from the approximate middle to the uppermost portion of the well screen, depending on well recovery rates during purging. The pumping rate was adjusted to minimize drawdown. The pumps were operated continuously during sampling to minimize aeration in the tubing.

Groundwater quality parameters including pH, specific conductance, turbidity, DO, temperature, and ORP were monitored during purging and were recorded on the groundwater sampling log for each monitoring well and are provided in Appendix B. Purging continued until the temperature, pH, and specific conductance had stabilized and the turbidity had either stabilized or was below 10 NTU. In accordance with the UST Programmatic QAPP (SCDHEC, 2020), stabilization was considered complete when pH measurements remained constant within 0.1 SU, or reproducible to within 0.1 SU, specific conductance varied no more than 10 percent, and the temperature was constant for at least three consecutive readings. A summary of field parameters collected during well purging is presented in Table 4-2.

4.1.3 Groundwater Sampling

Following the purging activities, groundwater samples were collected from two monitoring wells following procedures established in the UST Programmatic QAPP (SCDHEC, 2020).

Groundwater samples were analyzed for the following constituents by Pace. Pace currently holds a DoD ELAP certification and the SCDHEC Certification number is 32010001.

• Benzene and naphthalene by USEPA Method 8260B Analyses conformed to USEPA methodology described in Test Methods for Evaluating Solid Waste, Physical/Chemical Methods (USEPA, 2007) and in the UST Programmatic QAPP

Joint Base Charleston Weapons, South Carolina

Contract FA8903-15-C-0016 4-2 BWJ140078

(SCDHEC, 2020). Laboratory analytical results are present in Table 4-3 and analyte concentrations in excess of their respective RBSL are depicted on Figure 3-2. The field duplicate sample (see Section 4.1.4) is included in Table 4-3 along with the laboratory analytical results for the primary groundwater samples. Laboratory-prepared trip blanks, an equipment blank and a field blank were also included with sample shipments to the laboratory. The laboratory analytical report with chain of custody documentation is provided in Appendix E.

4.1.4 Quality Assurance and Quality Control Samples

Field quality control samples were collected to assure that data were of suitable quality to be used in the program. The following Quality Assurance and Quality Control samples were collected:

• One trip blank (01075-MW-1-BLDG-7-c).

4.2 Data Evaluation and Usability

One hundred percent of the analytical data were reviewed based on USEPA National Functional Guidelines for Organic Superfund Methods Data Review (USEPA, 2017), Department of Defense (DoD) Consolidated Quality Systems Manual for Environmental Laboratories, version 5.4 (DoD, 2021), and the Uniform Federal Policy – Quality Assurance Project Plan for Performance-Based Remediation, Basewide Groundwater, Surface Water, and Land Use Control Monitoring (Bay West, 2016). The data validation process included review of chains-of-custody, sample condition receipt forms, field duplicate sample RPDs, surrogate recoveries, equipment/method/trip blanks, LCS/LCSD recoveries and RPDs, and MS/MSD RPDs. Data was evaluated to verify the achievement of precision, accuracy, representativeness, completeness, comparability, and sensitivity goals established to meet the project data quality objectives.

Results of the evaluation suggest representative samples were collected and analyzed, and the results are representative of the media analyzed. No data qualifiers were added to the data as a result of the validation process and overall quality of the data collected is discussed in the Data Validation Report provided in Appendix F. The data reflect expected site conditions and should be considered compliant and adequate for their intended purpose.

4.3 Investigation-Derived Waste

IDW generated during the October 2022 field sampling activities consisted of monitoring well purge water. Purge water was pumped into 5-gallon graduated buckets during purging and sampling procedures then transferred into a 55-gallon polyethylene drum. Purge water generated during this sampling event was combined with the drum generated during the August 2022 sampling event. The 55-gallon drum was labeled with proper identifying and contact information, including source location, contents, and date collected. Drums are stored on JBC Weapons property within the Hazardous Waste Storage Area. Used personal protective equipment, primarily nitrile gloves and sample tubing, was consolidated into trash bags and placed into a dumpster behind Building 2 at JBC Weapons for disposal as non-hazardous waste at a Subtitle D Solid Waste Landfill, in accordance with the Basewide Soil QAPP (Bay West, 2016b).

The final manifest for disposal will be included in Appendix G in the Draft Final version of this document.

Joint Base Charleston Weapons, South Carolina

Contract FA8903-15-C-0016 5-1 BWJ140078

5.0 GROUNDWATER FLOW AND CONTAMINANT DISTRIBUTION

Groundwater flow and contaminant distribution at AOC B-3 (former Building 7) for the August and October 2022 performance monitoring events are discussed below.

5.1 Groundwater Elevations

Depths to groundwater were measured at each of the nine onsite monitoring wells on August 1, 2022, and October 7, 2022. The groundwater elevation ranged from 26.40 feet amsl at MW-7 to

27.05 feet amsl at MW-5-R during the August 2022 sampling event. The groundwater elevation ranged from 25.94 feet amsl at MW-1 to 28.59 feet amsl at MW-5-R during the October 2022 sampling event. As depicted on Figure 3-1 and Figure 4-1, groundwater flow is generally towards the northeast.

5.2 Contaminant Distribution

The concentrations of detected COCs during the August and October performance monitoring events are presented on Figure 3-2 and Figure 4-2. Table 5-1 presents a summary of historical COC analytical results for all nine on-site monitoring wells. Trend plots presented in Appendix F illustrate the concentrations of the COCs through the October 2022 monitoring event. Results of the sampling indicate the following:

• Benzene was not detected above the RBSL of 5 micrograms per liter (µg/L) at any monitoring well during the August 2022 monitoring event. Benzene was detected above the RBSL at MW-1 (6.5 µg/L) during the October 2022 monitoring event.

• Naphthalene was not detected above the RBSL of 25 µg/L at any monitoring wells during the August 2022 and October 2022 monitoring events.

Joint Base Charleston Weapons, South Carolina

Contract FA8903-15-C-0016 6-1 BWJ140078

6.0 CONCLUSIONS AND RECOMMENDATIONS

6.1 Conclusions

Assessment and remediation activities have been ongoing at AOC B-3 Former Building 7 (TU939) since 1998, when the 4,000-gallon UST was removed. Following the Hydrogeologic Assessment in 2002, routine groundwater monitoring was implemented to monitor site contaminants. Various AFVR events have been conducted at the site and were last employed in 2006.

In 2018, remedial activities were implemented to address benzene and naphthalene in soil and groundwater. As proposed in the CAP (AECOM, 2018) and detailed in the Construction Completion Report (AECOM, 2019), corrective action remedy implementation (soil excavation and groundwater treatment by injection) was completed in the fourth quarter of 2018 at Former Building 7. Treatment of groundwater by injection of ORC-A® was used to degrade petroleum hydrocarbons. As discussed during the November 2020 Tier 1 Meeting, MW-1 and MW-2-R were redeveloped prior to the sampling events to ensure proper contact with the aquifer. As presented in the AOC B-3 CAP Addendum, a supplemental injection will be conducted in 2022 using BOS 200® to address the benzene and naphthalene contamination remaining at the site in excess of screening levels. Two of four proposed performance monitoring events have been completed to evaluate the effectiveness of the supplemental injection. Benzene did not exceed the RBSL during the August 2022 monitoring event but did slightly exceed the RBSL in one monitoring well during the October 2022 monitoring event. Naphthalene did not exceed the RBSL during these two quarterly monitoring events

6.2 Recommendations

Based on the results of the performance monitoring events for this site, the following recommendations are made:

1. Continue depth to groundwater gauging in all nine monitoring wells.

2. Continue annual sampling of nine site monitoring wells for benzene and naphthalene.

3. Complete two additional quarterly post-injection performance monitoring events as outlined in the AOC B-3 CAP Addendum.

Joint Base Charleston Weapons, South Carolina

Contract FA8903-15-C-0016 7-1 BWJ140078

7.0 REFERENCES

AECOM, 2016. Annual Groundwater Monitoring Report, April 2016 Sampling Event for Area of Concern B-3 (TU939 and LUST ID 01075), Former Building #7 – Heat Plant, JBC Weapons, South Carolina. October.

AECOM, 2018. Corrective Action Plan, Area of Concern B-3 (TU939 and LUST ID 01075) Former Building 7 – Heat Plant, Joint Base Charleston - Weapons, Charleston, South Carolina.

February.

AECOM, 2019. Construction Completion Report for AOC B-3 (TU939 and LUST ID 01075), Former Building 7- Heat Plant, Joint Base Charleston Weapons, South Carolina. March.

AECOM, 2022a. Corrective Action Plan Addendum, Area of Concern B-3 (TU939 and LUST ID 01075) Former Building 7 – Heat Plant, Joint Base Charleston - Weapons, Charleston, South Carolina. January.

AECOM, 2022b. Annual Contractor Quality Assurance Plan. January.

Bay West, 2016a. Uniform Federal Policy – Quality Assurance Project Plan, Performance-Based

Remediation, Basewide Groundwater, Surface Water, and Land Use Control Monitoring, Joint Base Charleston Weapons, Joint Base Charleston Air, South Carolina. June.

Bay West, 2016b. Uniform Federal Policy – Quality Assurance Project Plan, Performance-Based Remediation, Basewide Soil Sampling and Analysis, Joint Base Charleston Weapons, South Carolina. February.

Department of Defense, 2018. Department of Defense Consolidated Systems for Environmental Laboratories. Version 5.1.1. January.

General Engineering and Environment, 2002. Hydrogeologic Assessment Report, Naval Weapons Station, Building 7, DHEC Site ID #01797-Common, Berkeley County, Goose Creek, South Carolina. May.

South Carolina Department of Health and Environmental Control, 2016. Risk Based Corrective Action for Petroleum Releases.

South Carolina Department of Health and Environmental Control, 2020. South Carolina Department of Health and Environmental Control Quality Assurance Project Plan for the UST Management Division, Rev 4.0. July.

United States Environmental Protection Agency, 2007. Test Methods for Evaluating Solid Waste (SW-846), Update IV. February.

United States Environmental Protection Agency, 2017. National Functional Guidelines for Organic Superfund Methods Data Review. Publication #EPA-540-R-2017-002. January.

Joint Base Charleston Weapons, South Carolina

Contract FA8903-15-C-0016 BWJ140078

Tables

Table 3-1 Groundwater Elevation Data - August 2022

AOC B-3, Former Building 7 Joint Base Charleston Weapons

Monitoring Well Date Top of Casing

Elevation (feet amsl)

Screened Interval (feet BTOC)

Total Well Depth (feet BTOC)

Depth to Water (feet BTOC)

Groundwater Elevation

(feet amsl)

MW-1 8/1/2022 33.45 5.99 - 15.99 15.82 6.87 26.58

MW-2-R 8/1/2022 33.22 4.50 - 14.50 15.40 6.57 26.65

MW-3 8/1/2022 33.58 5.55 - 15.55 15.80 6.71 26.87

MW-4 8/1/2022 33.37 5.97 - 15.97 14.69 6.41 26.96

MW-5-R 8/1/2022 33.62 5.80 - 15.80 16.00 6.57 27.05

MW-6 8/1/2022 33.26 5.81 - 15.81 16.08 6.37 26.89

MW-7 8/1/2022 32.80 5.91 - 15.91 16.20 6.40 26.40

MW-8 8/1/2022 33.41 5.91 - 15.91 16.18 6.81 26.60

MW-9 8/1/2022 33.41 6.07 - 16.07 14.31 6.54 26.87

Notes:

BTOC - below top of casing amsl - above mean sea level

Table 3-2 Summary of Groundwater Parameters - August 2022

AOC B-3, Former Building 7 Joint Base Charleston Weapons

MW-1 MW-2-R MW-3 MW-4 MW-5-R MW-6 MW-7

8/1/2022 8/1/2022 8/1/2022 8/1/2022 8/1/2022 8/1/2022 8/1/2022 pH S.U. 6.79 6.21 5.31 12.59 6.23 4.98 5.53

Specific Conductivity mS/cm 1.740 1.340 0.108 7.740 0.351 0.059 0.166 Turbidity NTU 4.10 3.45 0.49 3.28 3.81 2.01 3.97

Dissolved Oxygen mg/L 0.22 0.18 1.59 14.44 0.57 0.79 3.25 Temperature ˚C 30.20 30.20 28.10 29.90 31.20 30.10 28.10

ORP mV 17.3 -21.7 56.2 -46.7 105.6 124.6 24.6

Notes:

°C = degrees Celsius mg/L = milligrams per liter mS/cm = milliSiemens per centimeter mV = millivolt NTU = Nephelometric Turbidity Units ORP - oxidation reduction potential S.U. = Standard Units

Field Measurements Units

Sample Identification and Date Collected

Table 3-2 Summary of Groundwater Parameters - August 2022

AOC B-3, Former Building 7 Joint Base Charleston Weapons pH Specific Conductivity

Turbidity Dissolved Oxygen

Temperature

ORP

Notes:

°C = degrees Celsius mg/L = milligrams per liter mS/cm = milliSiemens per ce mV = millivolt NTU = Nephelometric Turbid ORP - oxidation reduction po S.U. = Standard Units

Field Measurements

MW-8 MW-9

8/1/2022 8/1/2022

5.75 6.65

0.122 0.870

3.15 3.71

0.21 4.30

29.70 28.70 -55.4 101.6

Table 3-3 Groundwater Analytical Results - August 2022

AOC B-3, Former Building 7 Joint Base Charleston - Weapons

Sample Identification and Date Collected

MW-1 MW-2-R MW-2-R-FD MW-3 MW-4 MW-5-R MW-6 MW-7

8/1/2022 8/1/2022 8/1/2022 8/1/2022 8/1/2022 8/1/2022 8/1/2022 8/1/2022 Benzene 5 1.3 ND ND Q/UJ ND ND ND Q/UJ ND 0.75 J/

Naphthalene 25 0.68 J/ ND ND Q/UJ ND ND ND Q/UJ 0.41 J/ 0.84 J/

Bold = constituent detected above the detection limit (DL) Bold = constituent detected above the SCDHEC RBSL value FD = Field Duplicate sample from monitoring well MW-2-R.

ND = Not Detected to the Limit of Detection (LOD). Detected results between the LOD and the detection limit (DL) have been flagged by the laboratory with "J" as estimated.

Samples analyzed by Pace Analytical Services, LLC located in West Columbia, South Carolina, a South Carolina certified laboratory.

SCDHEC RBSL = South Carolina Department of Health and Environmental Control Risk Based Screening Levels, from Table D1 of the South

Carolina Risk-Based Corrective Action For Petroleum Releases, dated February 2016 as found in the Quality Assurance Program Plan for the Underground Storage Tank Management Divisio SCDHEC sample analytical procedures include 8260D for benzene and naphthalene.

Units are µg/L (micrograms per liter)

Data Qualifiers:

The "/" separates the laboratory added data qualifiers from the validation data qualifiers. The laboratory added data qualifiers precede the "/," and the validation qualifiers follow the "/."

J/ = Indicates the result is between the DL and LOD.

/UJ = Undetected estimated.

Former Building 7

Monitoring Wells

Constituent of

Concern (µg/L)

SCDHEC

RBSL

Notes:

Q/ = Surrogate failure.

Table 4-1 Groundwater Elevation Data - October 2022

AOC B-3, Former Building 7 Joint Base Charleston Weapons

Monitoring Well Date Top of Casing

Elevation (feet amsl)

Screened Interval (feet BTOC)

Total Well Depth (feet BTOC)

Depth to Water (feet BTOC)

Groundwater Elevation

(feet amsl)

MW-1 10/7/2022 33.45 5.99 - 15.99 15.87 7.51 25.94

MW-2-R 10/7/2022 33.22 4.50 - 14.50 15.44 7.04 26.18

MW-3 10/7/2022 33.58 5.55 - 15.55 15.84 7.21 26.37

MW-4 10/7/2022 33.37 5.97 - 15.97 14.70 6.91 26.46

MW-5-R 10/7/2022 33.62 5.80 - 15.80 16.04 5.03 28.59

MW-6 10/7/2022 33.26 5.81 - 15.81 16.11 6.85 26.41

MW-7 10/7/2022 32.80 5.91 - 15.91 16.24 6.78 26.02

MW-8 10/7/2022 33.41 5.91 - 15.91 15.88 7.21 26.20

MW-9 10/7/2022 33.41 6.07 - 16.07 14.33 7.43 25.98

Notes:

BTOC - below top of casing amsl - above mean sea level

Table 4-2 Summary of Groundwater Parameters - October 2022

AOC B-3, Former Building 7 Joint Base Charleston Weapons

MW-1 MW-2-R

10/7/2022 10/7/2022 pH SU 6.15 6.00

Specific Conductivity mS/cm 0.820 0.680 Turbidity NTU 5.82 1.17

Dissolved Oxygen mg/L 0.23 0.11 Temperature ˚C 25.50 25.10

ORP mV -122.9 0.9

Notes:

°C = degrees Celsius mg/L =…