B.08 GFI JB CHS PBR LF003 (SWMU 3) Draft 2021 Annual Report redline.pdf

DRAFT

LONG-TERM MANAGEMENT / LAND USE CONTROL

REPORT 1 (2021)

PERFORMANCE-BASED REMEDIATION

Solid Waste Management Unit 3 (LF003)

Joint Base Charleston Weapons South Carolina

Contract FA8903-15-C-0016 April June 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

North Charleston, South Carolina 29405

With Teaming Partners:

Long-Term Monitoring/Land Use Control Report 1 (2021)

SWMU 3 (LF003)

Joint Base Charleston Weapons, South Carolina

Contract FA8903-15-C-0016 i BWJ140078

Certification Page

Registered South Carolina Professional Geologist

Certification

By affixing my seal to this report, I certify that the data and interpretations stated in this, Long-Term Management / Land Use Control Report 1 (2021) for SWMU 3 (LF003), Joint Base Charleston Weapons, South Carolina, are true and accurate to the best of my knowledge. I further certify that I am registered to practice geology in the State of South Carolina and that it is within my professional expertise to verify the correctness of this information.

Eva Rasdal Moore, PG. Date Registration Number 2462

Joint Base Charleston Weapons, South Carolina

Contract FA8903-15-C-0016 ii BWJ140078

TABLE OF CONTENTS

LIST OF FIGURES .................................................................................................................... iii LIST OF TABLES ...................................................................................................................... iii LIST OF APPENDICES ............................................................................................................. iii ACRONYMS AND ABBREVIATIONS ....................................................................................... iv

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

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

1.2 Site History and Previous Investigations .................................................................. 1-2

1.2.1 USGS Surface Water Assessment....................................................................... 1-2

1.2.2 RCRA Facility Investigation ................................................................................. 1-2

1.2.3 Baseline Risk Assessment ................................................................................... 1-2

1.2.4 Corrective Action ................................................................................................. 1-4

1.2.5 Periodic Groundwater Monitoring ......................................................................... 1-4

1.2.6 Plume Delineation ................................................................................................ 1-5

1.2.7 2017 Interim Measure .......................................................................................... 1-5

1.2.8 Corrective Measures Study and Statement of Basis ............................................ 1-5

1.2.9 Land Use Control Implementation Plan ................................................................ 1-6

1.3 Report Organization................................................................................................. 1-6

2.0 ANNUAL MONITORING ACTIVITIES .......................................................................2-1

2.1 Field Activities.......................................................................................................... 2-1

2.1.1 Groundwater Sample Collection and Handling ..................................................... 2-1

2.1.2 Surface Water Sample Collection and Handling................................................... 2-1

2.1.3 Laboratory Submittal and Analysis ....................................................................... 2-1

2.2 Data Evaluation and Usability .................................................................................. 2-2

2.3 Investigation Derived Waste Management ............................................................... 2-2

2.4 Annual Landfill Inspections and Maintenance .......................................................... 2-3

3.0 GROUNDWATER MONITORING RESULTS .............................................................3-1

3.1 2019 Analytical Results ........................................................................................... 3-1

3.1.1 Arsenic and Manganese Results ......................................................................... 3-1

3.1.2 Summary of Analytes Exceeding Project Action Levels ....................................... 3-1

3.2 2021 Analytical Results ........................................................................................... 3-2

3.2.1 Arsenic and Manganese Results ......................................................................... 3-2

3.2.2 Summary of Analytes Exceeding Project Action Levels ....................................... 3-2

4.0 CONCLUSIONS AND RECOMMENDATIONS ..........................................................4-1

4.1 Conclusions ............................................................................................................. 4-1

4.2 Recommendations ................................................................................................... 4-1

5.0 REFERENCES ..........................................................................................................5-1

Joint Base Charleston Weapons, South Carolina

Contract FA8903-15-C-0016 iii BWJ140078

List of Figures Figure 1 Joint Base Charleston Weapons Location Map Figure 2 SWMU 3 Location Map Figure 3 SWMU 3 Site Map Figure 4 SWMU 3 Potentiometric Surface Map (October 2019) Figure 5 SWMU 3 Potentiometric Surface Map (November 2021) Figure 6 SWMU 3 Arsenic Concentrations in Groundwater (October 2019) Figure 7 SWMU 3 Manganese Concentrations in Groundwater (October 2019) Figure 8 SWMU 3 Arsenic and Manganese Concentrations in Surface Water (2019) Figure 9 SWMU 3 Arsenic Concentrations in Groundwater (November 2021) Figure 10 SWMU 3 Manganese Concentrations in Groundwater (November 2021) Figure 11 SWMU 3 Arsenic and Manganese Concentrations in Surface Water (2021)

List of Tables Table 1 Well Construction Data Table 2 Groundwater Elevation Data Table 3 Groundwater Field Parameters Table 4 Groundwater and Surface Water Monitoring Matrix Table 5 Summary of Analytical Results in Groundwater - October 2019 Table 6 Summary of Surface Water Analytical Results – October 2019 Table 7 Summary of Analytical Results in Groundwater – November 2021 Table 8 Summary of Surface Water Analytical Results – November 2021 Table 9 Historical Arsenic and Manganese in Groundwater Table 10 Historical Arsenic and Manganese in Surface Water

List of Appendices Appendix A Field Documentation Appendix B Laboratory Analytical Data Appendix C Data Validation Reports Appendix D IDW Documentation Appendix E Landfill Inspection Documentation Appendix F Historical Analytical Graphs

Joint Base Charleston Weapons, South Carolina

Contract FA8903-15-C-0016 iv BWJ140078

ACRONYMS AND ABBREVIATIONS

µg/L............. micrograms per liter ABB-ES....... ABB Environmental Services, Inc.

AFCEC ....... Air Force Civil Engineer Center ARAR .......... applicable or relevant and appropriate requirement BRA ............ baseline risk assessment CMS ............ corrective measures study COPC ......... chemical of potential concern CSM ............ conceptual site model DO .............. dissolved oxygen DoD ............ Department of Defense EHC-M® ..... PeroxyChem EHC Metals ERA ............ ecological risk assessment ft ................. feet HHRA ......... human health risk assessment IDW ............. investigation-derived waste IM ............... interim measure JBC ............. Joint Base Charleston LCS ............. laboratory control sample LCSD .......... laboratory control sample duplicate LUC ............ land use control LUCIP ......... Land Use Control

Implementation Plan MCL ............ maximum contaminant level MCS ............ media cleanup standard mg/L ............ milligrams per liter MS .............. matrix spike MSD ............ matrix spike duplicate

ORP .............. oxidation-reduction potential PAL ............... project action level POMFLANT .. Polaris Missile Facility

Atlantic Fleet RCRA ............ Resource Conservation and

Recovery Act RFI ................ RCRA Facility Investigation RGO .............. remedial goal option RPD .............. relative percent difference RSL ............... regional screening level SCDHEC ....... South Carolina Department of Health and Environmental Control

SMCL ............ seconday maixmum contaminant levels

SoB ............... statement of basis SVOC ............ semi-volatile organic compounds SWMU........... solid waste management unit UFP-QAPP .... Uniform Federal Policy –

Quality Assurance Project Plan

USEPA .......... United States Environmental Protection Agency

USGS ............ United States Geological Survey

VOC .............. volatile organic compounds WP ................ work plan

Joint Base Charleston Weapons, South Carolina

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

1.0 INTRODUCTION

This Annual Report for Solid Waste Management Unit (SWMU) 3 at Joint Base Charleston (JBC) Weapons, South Carolina, has been prepared in accordance with the Resource Conservation and Recovery Act (RCRA) Permit Number SC8 170 022 620 issued to JBC Weapons by South Carolina Department of Health and Environmental Control (SCDHEC) in conjunction with Region 4 of the United States Environmental Protection Agency (USEPA). This document has been prepared under Air Force Civil Engineer Center (AFCEC) Contract Number FA8903-15-C-0016 in support of the JBC Weapons Environmental Restoration Program.

This Annual Report documents the completion of annual groundwater and surface water monitoring, and landfill inspection and maintenance conducted to address groundwater contaminants per the Uniform Federal Policy – Quality Assurance Project Plan (UFP-QAPP) and Corrective Measures Study (CMS) / Interim Measures (IM) Work Plan (CMS Work Plan, AECOM, 2016) for both 2019 and 2021. Groundwater monitoring procedures were performed following Uniform Federal Policy – Quality Assurance Project Plan, Basewide Groundwater, Surface Water, and Land Use Control Monitoring, Joint Base Charleston Weapons, Joint Base Charleston Air, South Carolina (Bay West, 2016a).

1.1 Site Description

JBC Weapons is located ten miles north of Charleston, South Carolina, approximately 16 miles inland from the Atlantic Ocean (Figure 1). The facility is situated in two counties, Berkeley and Charleston, and occupies 16,868 acres. The eastern section of the facility is bordered by the Cooper River and the Back River; the western section is bordered by the CSX Railroad. The facility, formerly Naval Weapons Station Charleston, has been under Air Force direction since October 1, 2010, and was renamed JBC Weapons.

JBC Weapons is divided into three sections: the northernmost section (referred to as Northside and formerly referred to as the Polaris Missile Facility Atlantic Fleet [POMFLANT] Area), the central section (referred to as Southside), and the southernmost section (referred to as the South Annex). The areas are managed separately by the Navy and are collectively referred to as JBC Weapons.

SWMU 3 occupies approximately 10 acres in the southwestern portion of the POMFLANT area and is adjacent to Foster Creek (Figure 2). Currently, SWMU 3 is not used for any purpose (recreational, industrial, commercial, residential, etc.) with the exception of seasonal hunting, and current land use at the site is not expected to change in the near future. The land surrounding SWMU 3 is undeveloped (Figure 3). The landfill, which operated from 1962 to 1978, received solid waste, oily waste, and solvents from the POMFLANT area, and large quantities of solid waste including construction and demolition debris, furniture, waste paving material, railroad ties, steel rails, and wooden crates. Liquid wastes included toluene, methyl ethyl ketone, acetone, and mineral spirit solvents; disposal rates were estimated to be 500 to 1,500 gallons annually.

A sandy clay soil cover was placed over the landfill in 1994 - 1995 to promote vegetation growth, minimize runoff, and prevent inadvertent contact with landfill materials. The soil cover is in place and is maintained with a grassy cover. The entrance to the site has a fence with a locking gate.

The maximum depth of the fill is estimated to be 5 feet (ft).

Joint Base Charleston Weapons, South Carolina

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

1.2 Site History and Previous Investigations

The following sections provide a summary of previous site investigations.

1.2.1 USGS Surface Water Assessment

From 1991 to 1993, the United States Geological Survey (USGS) performed an assessment on Foster Creek, which included the area around SWMU 3 (USGS, 1993). The purpose of the study was to assess potential release of contaminants to Foster Creek, which is a secondary source of drinking water for the Charleston area. Samples were collected from stream sediment and surface water. The results were summarized as follows:

“A number of naturally occurring inorganic compounds were detected throughout Foster Creek and its tributaries during low-flow surface water sampling. Of the inorganic compounds detected, three exceeded the USEPA [Secondary Maximum Contaminant Levels] (SMCLs): aluminum (650 micrograms per liter [µg/L] maximum), iron (2,740 µg/L maximum), and manganese (85.6 µg/L maximum).

These metals typically are found in surface water and ground water in the study region, and normally exceed the USEPA SMCL’s in nearly all coastal freshwater stations sampled by SCDHEC.”

1.2.2 RCRA Facility Investigation

Between 1993 and 1995, Phase I and II RCRA Facility Investigation (RFI) activities were conducted at SWMU 3 (ABB-ES, 1996). In 1993, a Phase I RFI was completed by ABB-ES at SWMU 3. The primary purpose of the investigation was to determine if contaminants from the site had adversely affected the water quality of Foster Creek.

A Human Health Risk Assessment (HHRA) and Ecological Risk Assessment (ERA) were conducted for constituents detected in site media collected from SWMU 3 during the RFI.

The Phase I RFI activities at SWMU 3 included:

• Ten surface water/sediment samples from drainage areas around the former landfill;

• One surface water/sediment sample from Foster Creek, downstream from the former landfill;

• Three subsurface soil samples from monitoring well borings; and

• Groundwater samples collected from nine monitoring wells located around the perimeter of the former landfill (NSW-3-1 through NWS-3-9).

The Phase II RFI activities at SWMU 3 included:

• Nine surface soil and five subsurface soil samples around the perimeter of the former landfill; and

• Groundwater samples from eight monitoring wells (NWS-3-1, NWS-3-2, NWS-3-3, NWS-3-5, NWS-3-7, NWS-3-8, NWS-3-9, and NWS-3-10). Wells NWS-3-4 and NWS-3-6 could not be located.

1.2.3 Baseline Risk Assessment

A Baseline Risk Assessment (BRA) for Corrective Action Management Plan Group A (which includes SWMUs 3, 4, 5, and 6) was prepared in 1996 (ABB-ES, 1996) based on information collected during the RFI and documented in the Supplemental RFI Workplan (ABB-ES, 1995).

Additional samples were collected, and a final BRA was developed in 1999 based on information collected during the supplemental RFI (ABB-ES, 1999). Qualitative and quantitative evaluations

Joint Base Charleston Weapons, South Carolina

Contract FA8903-15-C-0016 1-3 BWJ140078 of risks to human health and the environment were completed for exposures in surface soil, subsurface soil, sediment, surface water, and groundwater.

1.2.3.1 Human Health Risk Assessment

Surface soil, subsurface soil, and sediment were found not to pose any unacceptable carcinogenic or noncarinogenic risk to receptors. Surface water did not pose unacceptable carcinogenic or noncarcinogenic risks in current or future land use scenarios, although surface water quality criteria were exceeded for arsenic, iron, manganese, and mercury. Arsenic and mercury maximum surface water concentrations were less than or only slightly exceeded the detection limits, respectively. Therefore, risk-based remedial goal options (RGOs) were not necessary. Instead, applicable or relevant and appropriate requirement (ARAR)-based RGOs were presented for surface water for arsenic, iron, manganese, and mercury.

The results of the HHRA analysis determined that there are no current exposure risks to groundwater associated with SWMU 3. Groundwater is not currently being used and is not considered to be fresh water as sodium concentrations in groundwater exceed the SCDHEC benchmark of 450 milligram per liter (mg/L). However, estimated carcinogenic or noncarcinogenic risks to potential future residents from ingestion of groundwater as drinking water exceeded USEPA acceptable risk targets. The major contributors to the cancer risk are arsenic and beryllium, although beryllium was not detected above its maximum contaminant level (MCL) in groundwater samples from the site. The major noncancer risk drivers are aluminum, arsenic, and manganese. Therefore, risk-based RGOs were presented for groundwater for aluminum, arsenic, beryllium, and manganese. The maximum detected concentrations for iron and chromium exceeded Federal standards or State standards and guidance values (i.e., ARARs) so RGOs were developed for these analytes as well.

1.2.3.2 Ecological Risk Assessment

For the ERA, ecological chemicals of potential concern (COPCs) were selected and evaluated using a hazard assessment, exposure assessment, ecological effects assessment, risk characterization, and an uncertainty analysis similar to the HHRA.

Comparison of ecological COPCs for surface water, sediment, and groundwater to toxicity benchmarks suggests that aquatic receptors at SWMU 3 may be at risk from exposure to several inorganic analytes (aluminum, chromium, cobalt, iron, manganese, mercury, and lead). With the possible exception of lead and mercury, it is doubtful that the occurrence of these inorganic analytes is site related.

The ERA notes that assumptions inherent in the risk model for wildlife (including use of conservative reference toxicity values as well as extrapolation of bioaccumulation factors and toxicity data from small mammals to birds) may overestimate risks to wildlife at SWMU 3.

1.2.3.3 Conceptual Site Model

A conceptual site model (CSM) was developed using data from the RFI. The primary source of contaminants at SWMU 3 is waste disposed within the landfill. The primary release mechanism is direct deposition to surface soil. Infiltration/percolation was also identified as a potential primary release mechanism because liquid source materials were disposed in the landfill. Environmental media potentially impacted by release of source contamination included surface soil, subsurface soil, and groundwater beneath the unit. Potential impacts to the nearby creek and associated drainage areas may have occurred due to erosion of primary source materials or surface runoff.

However, this pathway was eliminated with the placement of the soil cover over the landfill material. Leaching from soils to groundwater with subsequent migration to discharge points along

Joint Base Charleston Weapons, South Carolina

Contract FA8903-15-C-0016 1-4 BWJ140078 seeps at Foster Creek and associated drainages were also identified as potential contaminant migration pathways.

1.2.4 Corrective Action

Corrective action was implemented at SWMU 3 in December 1994 and January 1995. Activities included removing the remaining construction debris, clearing vegetation, and using fill dirt to raise the elevation of the lower areas of the landfill. A one-ft thick clay cap was placed on the landfill surface after activities were complete (ABB-ES, 1995).

1.2.5 Periodic Groundwater Monitoring

Based on a regulatory meeting held February 4, 1998, a Groundwater Monitoring Work Plan for SWMU 3 (Tetra Tech, 1999) was developed to monitor trends in contaminant concentrations in groundwater through a five-year groundwater monitoring plan for the site (Tetra Tech, 1999). In July 1999, periodic groundwater monitoring was initiated at SWMU 3 in accordance with the five-year monitoring program. The first year of periodic monitoring was conducted quarterly and was reduced to annually during the second year. Landfill inspections were conducted during groundwater monitoring activities (ABB-ES, 1995).

Following completion of the five-year groundwater monitoring period, a Five-Year Review Report for Groundwater Monitoring was prepared documenting trends in groundwater concentrations (RCS, 2007). Based on the results from the monitoring program, arsenic and manganese were the only inorganic constituents consistently detected above MCLs and facility background.

Arsenic concentrations were centered on wells located near the middle of the landfill (NWS-3-1 and NWS-3-3). Elevated manganese concentrations are in wells located to the west of the landfill and do not appear to be related to contamination from the landfill. Recommendations were made to reduce the number of wells sampled during long-term monitoring from ten to six and to continue annual groundwater analyses.

The CSM presented in the 1996 RFI was updated as part of the Five-Year Review. It was concluded that results from the sediment, surface water and soil investigations support the assumptions of the CSM. Within the landfill, contaminated media were detected in only localized areas and no risk to human health was identified (ABB-ES, 1996). Given the age of the landfill, it is not likely that the primary release mechanisms remain as potential concerns. The groundwater monitoring data collected over the monitoring history of the unit further support that there has not been a sustained release of contaminants to groundwater.

Included in the Five-Year Review was a tidal study that was completed in November 2006. Based on the results of this study, it appears that monitoring wells NWS-3-8 and NWS-3-9 are directly impacted by tidal influences. The results of this tidal study further support that the elevated concentrations of manganese in groundwater do not appear to be related to contamination from the landfill, but rather, attributed to natural groundwater conditions and tidal influences on the geochemical conditions of shallow groundwater. These wells are located in an area that is frequently flooded and is adjacent to Foster Creek.

Periodic groundwater monitoring continued at six wells for volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), pesticides, and metals through 2011, the tenth year of periodic groundwater monitoring. Throughout monitoring, groundwater analytical results were compared to regulatory standards, facility background values, and risk-based screening levels.

Variations in groundwater concentrations over time have been evaluated and elevated metals concentrations continue to be present in some monitoring wells. In 2012, arsenic and manganese were observed at concentrations exceeding their respective MCLs and/or established background

Joint Base Charleston Weapons, South Carolina

Contract FA8903-15-C-0016 1-5 BWJ140078 levels (TEC-BSC, 2014). It was determined that arsenic in groundwater was not fully delineated along the west/southwestern side of the landfill.

Based on the HHRA and subsequent periodic groundwater monitoring, arsenic and manganese were determined to be COPCs in groundwater at SWMU 3. COPCs and media cleanup standards (MCSs) were presented in the UFP-QAPP and CMS/IM Work Plan (WP) (AECOM, 2016).

1.2.6 Plume Delineation

Plume delineation activities are documented in the 2016 Annual Report (AECOM, 2017) for SWMU 3. Investigation activities were completed in November 2016 and March 2017. Per the approved CMS/IM WP, wells NWS-3-3R and NWS-3-1RR were abandoned, three monitoring wells (NWS-3-10, NWS-3-11, and NWS-3-12) were installed at SWMU 3 to delineate the COPCs in groundwater downgradient of the landfill, and one well (NWS-3-14) was installed upgradient of the landfill.

Locations of new wells were selected based on proximity to the edge of the landfill surface and downgradient of wells NWS-3-8 and NWS-3-9. These wells have had elevated concentrations of arsenic and/or manganese, and the groundwater plume was not delineated in these areas along the western and southwestern boundary of the site. Wells NWS-3-10, NWS-3-11, and NWS-3-12 were located as far from the edge of the landfill surface (adjacent to the marsh) as was practical to define the groundwater plume in these areas. Well locations were limited by the presence of firm ground required to support drilling and well installation equipment.

The results from the 2016 annual groundwater monitoring event (included monitoring performed in November 2016 and March 2017) established baseline concentrations prior to implementation of IM. Concentrations of arsenic and manganese (total and dissolved) exceeded the respective project action level (PALs) in wells NWS-3-8, NWS-3-9, NWS-3-11, NWS-3-12, and NWS-3-13.

1.2.7 2017 Interim Measure The UFP-QAPP CMS/IM Work Plan proposed IMs for COPCs in groundwater. The objective of the IM was to evaluate the applicability of PeroxyChem EHC Metals (EHC-M®) as an amendment to remediate low levels of metals along the downgradient side of the landfill where arsenic and manganese concentrations have remained above the PALs in wells NWS-3-8 and NWS-3-9.

Injection activities were completed in March 2017. Post-injection surface and groundwater monitoring was performed in 2017 (June, September, and December) and 2018 (March). A detailed assessment of the IM injections can be found in the IM Completion Report (AECOM, 2018).

Contaminant concentrations fluctuated following injections with initial increases of arsenic and manganese in many wells. Arsenic and manganese are more soluble under reducing conditions and therefore more mobile, which may account for the initial increases of these COPCs. However, increased mobility means they are more likely to encounter and potentially adsorb to/precipitate with iron sulfide. Arsenic and manganese concentrations decreased to below PALs at select wells, however a consistent response was not observed at all wells located downgradient of the landfill.

Contaminants present in groundwater along the downgradient side of the landfill were not present in surface water at levels above their respective PALs. Surface water samples were collected during each of the post-injection monitoring events. All surface water analytical results for arsenic and manganese were below their respective PALs.

1.2.8 Corrective Measures Study and Statement of Basis

A Corrective Measures Study was developed for SWMU 3 in 2019 (AECOM, 2019). The CMS proposed a remedy natural attenuation, long term monitoring, land use controls, and contingency

Joint Base Charleston Weapons, South Carolina

Contract FA8903-15-C-0016 1-6 BWJ140078 in-situ chemical reduction. This document was approved by SCDHEC and a Statement of Basis (SoB) was developed and submitted in October 2020 (AECOM, 2020). The permit modification/renewal that will move the site to the Land Use Control (LUC) table is still pending.

1.2.9 Land Use Control Implementation Plan

Following the submission of the SoB, a Land Use Control Implementation Plan (LUCIP) was developed for SWMU 3. This plan was submitted as part of Attachment A to the Uniform Federal Policy – Quality Assurance Project Plan, Basewide Groundwater, Surface Water, and Land Use Control Monitoring, Joint Base Charleston Weapons, Joint Base Charleston Air, South Carolina (Bay West, 2016a). This LUCIP is currently awaiting SCDHEC approval and incorporation into the revised RCRA permit for JBC Weapons.

1.3 Report Organization

This document is organized into the following sections:

Section 1.0 Introduction: Presents the site description and history.

Section 2.0 Field Activities: Presents the 2019 and 2021 groundwater and surface water monitoring activities.

Section 3.0 Groundwater Monitoring Results: Presents the results from the 2019 and

2021 groundwater and surface water monitoring and analysis.

Section 4.0 Conclusions and Recommendations: Provides a summary of the information presented in the report.

Section 5.0 References

Joint Base Charleston Weapons, South Carolina

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

2.0 ANNUAL MONITORING ACTIVITIES

The following presents a summary of the annual monitoring activities conducted at SWMU 3 during the October 2019 and November 2021 sampling events.

2.1 Field Activities

Groundwater and surface water monitoring activities were completed in October 2019 and November 2021. Field activities included the collection of depth to groundwater level measurements, collection of groundwater samples at all onsite monitoring wells, collection of three surface water samples, and the completion of a landfill inspection.

All groundwater and surface water monitoring activities were performed according to the procedures outlined in the CMS Work Plan (AECOM, 2016) and/or the LUCIP (AECOM, 2020) and the Uniform Federal Policy – Quality Assurance Project Plan, Basewide Groundwater, Surface Water, and Land Use Control Monitoring, Joint Base Charleston Weapons, Joint Base Charleston Air, South Carolina (Bay West, 2016a). No deviations from the planned sampling events occurred.

2.1.1 Groundwater Sample Collection and Handling

Prior to collection of groundwater samples, the depth to groundwater was measured using an electronic water level meter. Monitoring well construction details are presented in Table 1, and calculated groundwater elevations are presented on Table 2. Contoured groundwater elevation maps are provided as Figures 4 and 5. Field documentation is provided in Appendix A.

Groundwater samples were collected following low-flow purging methods. Purging of the monitoring wells was performed using a peristaltic pump with Teflon®-lined polyethylene tubing.

New tubing was used at each well during sample collection to eliminate the potential for cross-contamination. Low-flow purging and sampling were performed as detailed in the USEPA publication Ground Water Issue: Low-Flow (Minimal Drawdown) Ground-Water Sampling Procedures (USEPA, 1996) and Uniform Federal Policy – Quality Assurance Project Plan, Basewide Groundwater, Surface Water, and Land Use Control Monitoring, Joint Base Charleston Weapons, Joint Base Charleston Air, South Carolina (Bay West, 2016a). Field parameters (dissolved oxygen [DO], pH, temperature, oxygen reduction potential [ORP], and specific conductivity) were measured with a YSI 556 (or equivalent) and recorded periodically during purging activities. Groundwater samples were collected following field parameter stabilization.

Field parameters are presented on Table 3. Field documentation is provided as Appendix A.

2.1.2 Surface Water Sample Collection and Handling

Surface water samples were collected via grab sample. Sampling was performed as detailed in the Uniform Federal Policy – Quality Assurance Project Plan, Basewide Groundwater, Surface Water, and Land Use Control Monitoring, Joint Base Charleston Weapons, Joint Base Charleston Air, South Carolina (Bay West, 2016a). Field parameters (DO, pH, temperature, ORP, and specific conductivity) were measured with a YSI 556 (or equivalent) and recorded at the time of sample collection. Field documentation is provided as Appendix A.

2.1.3 Laboratory Submittal and Analysis

All sample containers were supplied by the analytical laboratory. Sample collection activities were coordinated with the analytical laboratory so that the proper containers, with appropriate preservatives, were provided that hold sufficient sample volumes. After preservation, all samples were stored in a cooler on ice until shipment to the laboratory. All samples were packaged for

Joint Base Charleston Weapons, South Carolina

Contract FA8903-15-C-0016 2-2 BWJ140078 shipment in a controlled environment to ensure sample integrity. The samples were shipped on ice to maintain a temperature of approximately 4 degrees Celsius.

All samples were submitted to Pace Analytical Gulf Coast in Baton Rouge, Louisiana, a South Carolina certified, off-site fixed laboratory for the analyses shown on Table 4. Chain of custody forms were completed to document sample custody and allow traceability of the sample history.

Copies of the chains of custody have been included in the laboratory analytical data packages provided electronically in Appendix B.

Groundwater samples were analyzed for the following constituents by Pace Analytical Gulf Coast of Baton Rouge, Louisiana (SCDHEC Certification Number 73006001):

• Total Metals by USEPA Method 6020B

• Dissolved Metals by USEPA Method 6020B

• VOCs by USEPA Method 8260B

• SVOCs by USEPA Method 8270D

• Pesticides by USEPA Method 8081B

• Mercury by USEPA Method 7470A

Surface water samples were analyzed for the following constituents by Pace Analytical Gulf Coast of Baton Rouge, Louisiana (SCDHEC Certification Number 73006001):

• Total Metals (Arsenic and Manganese) by USEPA Method 6020B

2.2 Data Evaluation and Usability

One hundred percent of the analytical data were reviewed based on USEPA National Functional Guidelines for Inorganic Superfund Methods Data Review (USEPA, 2017a), USEPA National Functional Guidelines for Organic Superfund Methods Data Review (USEPA, 2017b), Department of Defense (DoD) Consolidated Quality Systems Manual for Environmental Laboratories [version 5.1 (DoD, 2017) for the October 2019 data and version 5.1.1 (DoD, 2018) for the November 2021 data], 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). The data validation process included review of chains-of-custody, sample condition receipt forms, field duplicate samples, surrogate recoveries, method/trip blanks, laboratory control sample/laboratory control sample duplicate (LCS/LCSD) recoveries and relative percent differences (RPDs), and matrix spike/matrix spike duplicate (MS/MSD) recoveries and 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. The overall quality of the data collected is discussed in the Data Validation Reports provided in Appendix C. Data qualifiers were added to the data as a result of the validation process (trip blank contamination, field duplicate RPDs, LCS recoveries, MS recoveries, and MS/MSD RPD); however, the data reflect expected site conditions and should be considered compliant and adequate for their intended purpose.

2.3 Investigation Derived Waste Management

Investigation derived waste (IDW) consisting of purge water was contained in 55-gallon drums.

One drum was generated during the sampling event. Drums are properly labeled and stored at the Hazardous Waste Storage Yard (Building 2306) prior to disposal. On December 20, 2019, one drum (Manifest #06436) of purge water was transported by A&D Environmental Services, LLC to their facility in Macon, Georgia. On March 16, 2022, one drum (Manifest #06787) of purge

Joint Base Charleston Weapons, South Carolina

Contract FA8903-15-C-0016 2-3 BWJ140078 water was transported by Envirosmart to Lee County Solid Waste Facility in Bishopville, South Carolina for proper disposal. The final non-hazardous waste manifests for disposal from the 2019 and 2021 sampling events are included in Appendix D.

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 Uniform Federal Policy – Quality Assurance Project Plan for Basewide Soil Sampling and Analysis (Bay West, 2016b).

2.4 Annual Landfill Inspections and Maintenance

The 2019 landfill inspection was performed in October. The landfill was in acceptable condition with no erosion or damage of the soil cap observed. Activities including clearing around the monitoring wells and mowing the top of the cap were completed in 2019. The 2021 landfill inspection was performed in November. The landfill was in acceptable condition with no erosion or damage of the soil cap observed. Activities including clearing around the monitoring wells and mowing the top of the cap were completed in 2021. Vegetation maintenance will continue to be performed around monitoring wells and around the cap perimeter periodically as needed and prior to the next annual monitoring event. Landfill inspection field notes are provided as Appendix E.

Joint Base Charleston Weapons, South Carolina

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

3.0 GROUNDWATER AND SURFACE WATER MONITORING

RESULTS

The groundwater compliance points are used to monitor plume extent and to monitor the perimeter of the landfill. The analytical results from the 2019 groundwater and surface water sampling events are presented in Tables 5 and 6, respecivelyrespectively. The analytical results from the 2019 2021 groundwater and surface water sampling events are presented in Tables 7 and 8, respectively. The historical analytical results for arsenic and manganese in groundwater and surface water are presented in Tables 9 and 10, respectively. Isoconcentration maps for 2019 monitoring for arsenic and/or manganese are presented as Figures 6 through 8.

Isoconcentration maps for 2021 monitoring for arsenic and/or manganese are presented as Figures 9 through 11. Graphs of arsenic and manganese concentrations in groundwater are presented as Appendix F.

3.1 2019 Analytical Results The following presents the analytical results for the 2019 Annual Monitoring Event.

3.1.1 Arsenic and Manganese Results

Arsenic concentrations were above the MCL (10 µg/L) at wells NWS-3-8 (total and dissolved), NWS-3-9 (total), and NWS-3-13 (total and dissolved) as shown on Table 5. Concentrations of arsenic which exceed the MCL range from 10.2 µg/L to 66.3 µg/L as shown on Figure 6. Arsenic concentrations (total and dissolved) were below the MCL (10 µg/L) at all other wells (NWS-3-4A, NWS-3-5R, NWS-3-10, NWS-3-11, NWS-3-12, and NWS-3-14). Concentrations of field filtered (dissolved) metals samples were generally slightly lower than the total metals samples, but no significant differences were observed between filtered (dissolved) and non-filtered (total) samples.

Manganese concentrations (total and dissolved) were above the regional screening level (RSL) (440 µg/L) at wells NWS-3-8, NWS-3-9, NWS-3-11 and NWS-3-12 (Table 5). Concentrations of manganese which exceed the RSL range from 603 µg/L to 1,860 µg/L as shown on Figure 7.

Manganese concentrations (total and dissolved) were below the RSL (440 µg/L) at all other wells (NWS-3-4A, NWS-3-5R, NWS-3-10, NWS-3-13 and NWS-3-14). Concentrations of field filtered (dissolved) metals samples were generally slightly lower than the total metals samples, but no significant differences were observed between filtered (dissolved) and non-filtered (total) samples.

Arsenic and manganese concentrations (total) were below the MCL for arsenic (10 µg/L) and RSL for manganese (440 µg/L) at all three surface water locations (Table 6 and Figure 8).

3.1.2 Summary of Analytes Exceeding Project Action Levels

Arsenic and manganese results are discussed above. No other metals are COPCs. Iron was detected at well NWS-3-10 at concentrations of 48,700 µg/L (total) and 45,200 µg/L (dissolved), which exceed the PAL of 14,000 µg/L.

Methylene chloride was detected above the PAL of 5 µg/L in wells NWS-3-4A, NWS-3-5R, NWS- 3-8, and NWS-3-13. Concentrations ranged from 10.7 µg/L to 116 µg/L. No SVOCs were detected above their respective PAL. No VOCs or SVOCs are COPCs.

The pesticide aldrin was detected at well NWS-3-10 (0.0041 JP µg/L), which exceeds the PAL of

0.00092 µg/L. Aldrin was previously detected in well NWS-3-11 in 2016 but has not been detected in groundwater samples collected in 2008, 2012, 2017 or 2018. Additional monitoring is necessary to determine if this detection is anomalous. No other pesticides were detected above their respective PALs. No pesticides are COPCs.

Joint Base Charleston Weapons, South Carolina

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

3.2 2021 Analytical Results The following presents the analytical results for the 2021 Annual Monitoring Event.

3.2.1 Arsenic and Manganese Results

Arsenic concentrations (total and dissolved) were above the MCL (10 µg/L) at wells NWS-3-8, NSW-3-9, and NWS-3-13 (Table 7). Concentrations of arsenic which exceed the MCL range from

10.0 µg/L to 40.5 µg/L as shown on Figure 9. Arsenic concentrations (total and dissolved) were below the MCL (10 µg/L) at all other wells (NWS-3-4A, NWS-3-5R, NWS-3-10, NWS-3-11, NWS-3-12, and NWS-3-14). Concentrations of field filtered (dissolved) metals samples were generally slightly lower than the total metals samples, but no significant differences were observed between filtered (dissolved) and non-filtered (total) samples.

Manganese concentrations (total and dissolved) were above the regional screening level (RSL) (440 µg/L) at wells NWS-3-8, NWS-3-9, NWS-3-11 and NWS-3-12 (Table 7). Concentrations of manganese which exceed the RSL range from 522 µg/L to 2,040 µg/L as shown on Figure 10.

Manganese concentrations (total and dissolved) were below the RSL (440 µg/L) at all other wells (NWS-3-4A, NWS-3-5R, NWS-3-10, NWS-3-13 and NWS-3-14). Concentrations of field filtered (dissolved) metals samples were generally slightly lower than the total metals samples, but no significant differences were observed between filtered (dissolved) and non-filtered (total) samples.

Arsenic and manganese concentrations (total) were below the MCL for arsenic (10 µg/L) and RSL for manganese (440 µg/L) at all three surface water locations (Table 8 and Figure 11).

3.2.2 Summary of Analytes Exceeding Project Action Levels

Arsenic and manganese results are discussed above. No other metals are COPCs. Iron was detected at well NWS-3-10 at concentrations of 48,800 µg/L (total) and 46,600 µg/L (dissolved), which exceed the PAL of 14,000 µg/L.

No VOCs or SVOCs were detected above their respective PAL. No VOCs or SVOCs are COPCs.

The pesticide alpha-BHC was detected at well NWS-3-8 (0.016 J µg/L), which exceeds the PAL of 0.0072 µg/L. Additional monitoring is necessary to determine if this detection is anomalous. No other pesticides were detected above their respective PALs. No pesticides are COPCs.

Joint Base Charleston Weapons, South Carolina

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

4.0 CONCLUSIONS AND RECOMMENDATIONS

4.1 Conclusions

This report documents the 2019 and 2021 annual groundwater and surface water monitoring activities and annual landfill inspection and maintenance.

Annual groundwater monitoring was performed at nine monitoring wells. Annual surface water monitoring was performed at three locations. Analytical results remain consistent with previous sampling events in both 2019 and 2021. Arsenic was detected in three monitoring wells above the PAL of 10 µg/L in 2019 and in 2021. Manganese was detected in four monitoring wells above the PAL of 440 µg/L in both 2019 and 2021. Overall, concentrations are generally decreasing (Appendix F). Neither COPC was detected above its respective PAL in the surface water compliance points in 2019 or 2021.

The 2019 and 2021 annual landfill inspections documented that institutional controls are in place and functioning as intended and that the vegetative cover is in good condition. General maintenance to the vegetative cover was completed and will be performed around monitoring wells and around the cap perimeter periodically as needed and prior to the next annual monitoring event.

4.2 Recommendations

It is recommended that annual groundwater sampling, surface water sampling, and LUC inspections continue per the LUCIP. Results of the 2022 sampling will be presented in the 2022 Long-Term Monitoring/LUC Report.

Joint Base Charleston Weapons, South Carolina

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

5.0 REFERENCES

ABB-ES, 1995. Technical Memorandum and Supplemental Resource Conservation and

Recovery Act Facility Investigation Workplan, Camp Group A, Naval Weapons Station, Charleston, South Carolina. April.

ABB-ES, 1996. Final Draft Baseline Risk Assessment for Corrective Action Management Plan Group A, Naval Weapons Station, Charleston South Carolina, prepared for Department of the Navy, Southern Division, Naval Facilities Engineering Command, Contract No.

N62467-89-D-0317/032, June 1999.

ABB-ES, 1999. Final Baseline Risk Assessment for Corrective Action Management Plan Group A, Naval Weapons Station, Charleston South Carolina, prepared for Department of the Navy, Southern Division, Naval Facilities Engineering Command, Contract No. N62467- 89-D-0317/032, June 1999.

AECOM, 2016. Uniform Federal Policy – Quality Assurance Project Plan and Corrective Measures Study/Interim Measures Work Plan, SWMU 3, Joint Base Charleston Weapons.

September.

AECOM, 2017. Interim Measures Report, SWMU 3, Joint Base Charleston Weapons, Charleston, South Carolina. July.

AECOM, 2018. Interim Measures Completion Report, SWMU 3, Joint Base Charleston Weapons, Charleston, South Carolina. November.

AECOM, 2019. Corrective Measures Study, SWMU 3, Joint Base Charleston Weapons, Charleston, South Carolina. October.

AECOM, 2020. SWMU 3 (LF003) Monitoring and LUC Inspection Work Plan, Joint Base Charleston Weapons, Charleston, South Carolina. December.

Bay West, 2016a. Uniform Federal Policy – Quality Assurance Project Plan, Basewide Groundwater, Surface Water, and Land Use Control Monitoring, Joint Base Charleston Weapons, Joint Base Charleston Air, South Carolina.

Bay West, 2016b. Uniform Federal Policy – Quality Assurance Project Plan for Basewide Soil Sampling and Analysis, Joint Base Charleston Weapons, Joint Base Charleston Air, South Carolina (Bay West, 2016b).

Department of Defense, 2017. Department of Defense Consolidated Systems for Environmental Laboratories. Version 5.1. January.

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

RCS Corporation, 2007. Year 5 Long Term Monitoring Report, SWMU 3, Naval Weapons Station.

Charleston, South Carolina. November

South Carolina Department of Health and Environmental Control. Bureau of Land and Waste Management. Revised, 2015. Resource Conservation and Recovery Act (RCRA) Part B

Joint Base Charleston Weapons, South Carolina

Contract FA8903-15-C-0016 5-2 BWJ140078 permit number SC8 170 022 620, effective 22 September 2011 through 22 September 2021.

Tetra Tech, 1999. Groundwater Monitoring Work Plan for SWMU 3 – Old North Side Landfill, Naval Weapons Station Charleston, Charleston, SC. July.

TEC-BSC Joint Venture, 2014. Final 2012 Annual Monitoring Report, SWMU 3 – Old North Side Landfill, Naval Weapons Station Charleston, Charleston, SC. March.

United States Environmental Protection Agency Publication, 1996. Ground Water Issue: Low- Flow (Minimal Drawdown) Ground-Water Sampling Procedures.

United States Environmental Protection Agency, 2017a. National Functional Guidelines for Inorganic Superfund Methods Data Review. Publication #EPA-540-R-2017-001. January.

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

United States Geological Survey, 1993. Water Quality, Bed-Sediment Quality, and Simulation of Potential Contaminant Transport in Foster Creek, Berkeley County, South Carolina, 1991-

Joint Base Charleston Weapons, South Carolina

Contract FA8903-15-C-0016 BWJ140078

Figures

Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community, Sources: Esri, HERE, DeLorme, USGS, Intermap, INCREMENT P, NRCan, Esri Japan, METI, Esri China (Hong Kong), Esri Korea, Esri (Thailand), MapmyIndia, NGCC, © OpenStreetMap contributors, and the GIS User Community

Figure 1 Joint Base Charleston Weapons

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Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community

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