W912DR18R0055_-_Attachment_BQ_-2017_OU6_and_OU7_Report_Draft_7-2018.pdf

DRAFT

2017 ANNUAL GROUNDWATER AND SURFACE WATER

MONITORING REPORT

OPERABLE UNITS 6 &7

DEFENSE SUPPLY CENTER RICHMOND

Prepared For

Defense Logistics Agency

And

Defense Supply Center Richmond

DRAFT

2017 ANNUAL GROUNDWATER AND SURFACE WATER

MONITORING REPORT

OPERABLE UNITS 6 & 7

DEFENSE SUPPLY CENTER RICHMOND

Prepared For:

Defense Supply Center Richmond

Defense Logistics Agency

United States Army Corps of Engineers, Tulsa District

Prepared By:

Arcadis U.S., Inc.

Contract No. W912DR-13-D0019

Task Order 0005

July 2018

Table of Contents

EXECUTIVE SUMMARY .......................................................................................................... 1-8

1 INTRODUCTION ............................................................................................................... 1-9

1.1 Purpose and Objectives ........................................................................................... 1-10

1.2 Facility Background................................................................................................. 1-10

1.3 Operable Unit 6 ........................................................................................................ 1-11

1.4 Operable Unit 7 ........................................................................................................ 1-13

1.5 Surface Water – OU6 and OU7 .............................................................................. 1-13

2 FIELD ACTIVITIES .......................................................................................................... 2-1

2.1 Groundwater Elevation Measurements ................................................................... 2-1

2.2 Sampling and Analysis Activities ............................................................................. 2-1

2.2.1 Low Flow Groundwater Sampling........................................................................... 2-2

2.2.2 Surface Water Sampling .......................................................................................... 2-4

2.3 Monitoring Well Inventory and Inspection ............................................................. 2-5

2.4 Investigation-Derived Waste Management and Disposal ...................................... 2-5

2.5 Variances/Non-conformances ................................................................................... 3-1

3 RESULTS AND RECOMMENDATIONS ........................................................................ 4-1

3.1 Operable Unit 6 .......................................................................................................... 4-1

3.1.1 Groundwater Flow ................................................................................................... 4-1

3.1.2 Analytical Results .................................................................................................... 4-1

3.1.3 MNA Evaluation – Operable Unit 6 ........................................................................ 4-9

3.1.4 Leachability Assessment – OU 6 ........................................................................... 4-10

3.2 Operable Unit 7 ........................................................................................................ 4-11

3.2.1 Groundwater Flow ................................................................................................. 4-11

3.2.2 Analytical Results .................................................................................................. 4-11

3.2.3 MNA Evaluation – Operable Unit 7 ...................................................................... 4-16

3.2.4 Leachability Assessment – OU 7 ........................................................................... 4-17

3.3 DATA QUALITY EVALUATION ........................................................................ 4-17

3.4 Trend Analysis ......................................................................................................... 4-18

3.4.1 Trend Assessment – OU 6 ..................................................................................... 4-19

3.4.2 Trend Assessment – OU 7 ..................................................................................... 4-19

3.5 Surface Water Sampling Results ............................................................................ 4-20

3.5.1 Analytical Results .................................................................................................. 4-20

3.6 Conclusions/Recommendations .............................................................................. 4-20

4 REFERENCES ................................................................................................................... 5-1

List of Figures

Figure 1-1: Defense Supply Center Richmond Operable Units

Figure 1-2: Operable Unit 6

Figure 1-3: Operable Unit 7

Figure 2-1: OU 6 Monitoring Well and Surface Water Sample Locations

Figure 2-2: OU 7 Monitoring Well and Surface Water Sample Locations

Figure 4-1: OU 6 Upper WBU Potentiometric Surface Contours

Figure 4-2: OU 6 Lower WBU Potentiometric Surface Contours

Figure 4-3: OU 6 Upper WBU Total Volatile Organic Compound Isoconcentration Map

Figure 4-4: OU 6 Upper WBU PCE

Figure 4-5: OU 6 Upper WBU TCE Isoconcentration Map

Figure 4-6: OU 6 Upper WBU cis-1,2-DCE Isoconcentration Map

Figure 4-7: OU 6 Upper WBU VC Isoconcentration Map

Figure 4-8: OU 6 Upper WBU VOC Detections Above MCLs

Figure 4-9: OU 6 Upper WBU Ethene, Ethane, and Methane Isoconcentration Map

Figure 4-10: OU 6 Lower WBU Total Volatile Organic Compound Isoconcentration Map

Figure 4-11: OU 6 Lower WBU PCE Isoconcentration Map

Figure 4-12: OU 6 Lower WBU TCE Isoconcentration Map

Figure 4-13: OU 6 Lower WBU cis-1,2-DCE Isoconcentration Map

Figure 4-14: OU 6 Lower WBU VC Isoconcentration Map

Figure 4-15: OU 6 Lower VOC Detections Above MCLs Isoconcentration Map

Figure 4-16: OU 6 Lower WBU Ethene, Ethane, and Methane Isoconcentration Map

Figure 4-17: OU 7 Lower WBU Potentiometric Surface Contours

Figure 4-18: OU 7 Saprolite Potentiometric Surface Contours

Figure 4-19: OU 7 Lower WBU Total Volatile Organic Compound Isoconcentration Map

Figure 4-20: OU 7 Lower WBU PCE Isoconcentration Map

Figure 4-21: OU 7 Lower WBU TCE Isoconcentration Map

Figure 4-22: OU 7 Lower WBU cis-1,2-DCE Isoconcentration Map

Figure 4-23: OU 7 Lower WBU VC Isoconcentration Map

Figure 4-24: OU 7 Lower WBU VOC Detections Above MCLs

Figure 4-25: OU 6 Lower WBU Ethene, Ethane, and Methane Isoconcentration Map

Figure 4-26: OU 7 Saprolite WBU Total Volatile Organic Compound Isoconcentration

Map

Figure 4-27: OU 7 Saprolite WBU PCE Isoconcentration Map

Figure 4-28: OU 7 Saprolite WBU TCE Isoconcentration Map

Figure 4-29: OU 7 Saprolite WBU cis-1,2-DCE Isoconcentration Map

Figure 4-30: OU 7 Saprolite WBU VC Isoconcentration Map

Figure 4-31: OU 7 Saprolite WBU VOC Detections Above MCLs Isoconcentration Map

Figure 4-32: OU 7 Saprolite WBU Ethene, Ethane, and Methane Isoconcentration Map

List of Tables

Table 2-1: OU 6 Water Levels

Table 2-2: OU 7 Water Levels

Table 2-3: OU 6 Samples and Analyses

Table 2-4: OU 7 Samples and Analyses

Table 4-1: OU 6 Upper WBU - Volatile Organic Compounds

Table 4-2: OU 6 Lower WBU – Volatile Organic Compounds

Table 4-3: OU 6 Saprolite WBU - Volatile Organic Compounds

Table 4-4: OU 6 Upper WBU - Field and Natural Attenuation Parameters

Table 4-5: OU 6 Lower WBU - Field and Natural Attenuation Parameters

Table 4-6: OU 6 Saprolite WBU - Field and Natural Attenuation Parameters

Table 4-7: OU 6 Upper WBU Leachability Assessment – SVOCs and 1,4-Dioxane

Table 4-8: OU 6 Upper WBU Leachability Assessment - Metals

Table 4-9: OU 7 Lower WBU Volatile Organic Compounds

Table 4-10: OU 7 Saprolite WBU - Volatile Organic Compounds

Table 4-11: OU 7 Lower WBU - Field and Natural Attenuation Parameters

Table 4-12: OU 7 Saprolite WBU - Field and Natural Attenuation Parameters

Table 4-13: OU 7 Lower WBU Leachability Assessment – SVOCs

Table 4-14: OU 7 Lower WBU Leachability Assessment – Metals, PCBs

Table 4-15: OU 6 Upper WBU Trend Analysis

Table 4-16: OU 6 Lower WBU Trend Analysis

Table 4-17: OU 7 Lower WBU Trend Analysis

Table 4-18: OU 7 Saprolite WBU Trend Analysis

Table 4-19: OU 6 Surface Water – Volatile Organic Compounds

Table 4-20: OU 7 Surface Water – Volatile Organic Compounds

List of Appendices

APPENDIX A: FIELD DOCUMENTATION

APPENDIX A1a: OU 6 WELL SAMPLING FORMS

APPENDIX A1b: OU 7 WELL SAMPLING FORMS

APPENDIX A2a: OU 6 FIELD NOTES

APPENDIX A2b: OU 7 FIELD NOTES

APPENDIX A3a: OU 6 CHAIN-OF-CUSTODY FORMS

APPENDIX A3b: OU 7 CHAIN-OF-CUSTODY FORMS

APPENDIX A4: SURFACE WATER SAMPLING FORMS

APPENDIX A5: IDW DISPOSAL DOCUMENTATION

APPENDIX B: LABORATORY ANALYTICAL DATA RESULTS

APPENDIX C: DATA VALIDATION REPORTS

APPENDIX C1a: OU 6 DATA VALIDATION REPORTS

APPENDIX C1b: OU 7 DATA VALIDATION REPORTS

APPENDIX C2: DATA QUALITY EVALUATION

APPENDIX D: OU 6 AND OU 7 VOC CONCENTRATION TREND ANALYSES

APPENDIX D1: OU 6 UPPER WBU VOC TREND ANALYSIS

APPENDIX D2: OU 6 LOWER WBU VOC TREND ANALYSES

APPENDIX D3: OU 7 LOWER WBU VOC TREND ANALYSES

APPENDIX D4: OU 7 SAPROLITE WBU VOC TREND ANALYSES

Acronyms and Abbreviations µg/L Micrograms Per Liter

1,1,1-TCA 1,1,1-trichloroethane

1,1-DCE 1,1-dichloroethene

1,4-DCB 1,4-dichlorobenzene

2,3,7,8-TCDD 2,3,7,8-tetrachlorodibenzo-p-dioxin

AECOM AECOM Technical Services

Arcadis Arcadis U.S., Inc.

cis-1,2-DCE cis-1,2-dichloroethene

COC Contaminants of Concern

CVOC Chlorinated Volatile Organic Compound

DLA Defense Logistics Agency

DO Dissolved Oxygen

DQE Data Quality Evaluation

DQI Data Quality Indicator

DSCR Defense Supply Center Richmond

EVO Emulsified Vegetable Oil

FTA Fire Training Area

HHBRA Human Health Baseline Risk Assessment

IDW Investigation-derived Waste

ISB In-situ Bioremediation

LTM Long Term Monitoring

MCL Maximum Concentration Level mg/L Milligrams Per Liter mV Millivolts

MNA Monitored Natural Attenuation

NGA National Guard Area

ORP Oxidation-reduction Potential

OU Operable Unit

PAH Polycyclic Aromatic Hydrocarbon

PCB Polycyclic Chlorinated Biphenyls

PCE Tetrachloroethene

QAPP Quality Assurance Project Plan

ROD Record of Decision

RSL Regional Screening Level

SVOC Semi-volatile Organic Compound

TCE Trichloroethene

USEPA U.S. Environmental Protection Agency

VC Vinyl Chloride

VOC Volatile Organic Compound

WBU Water Bearing Unit

EXECUTIVE SUMMARY

This report presents the results of groundwater and surface water sampling performed during April

2017 at Operable Units (OUs) 6 and 7 at the Defense Supply Center Richmond, located near

Richmond, Virginia.

A biannual groundwater sampling program was initiated in July 2005 to monitor contaminant concentrations and natural attenuation of volatile organic compounds (VOCs) in OUs 6 and 7. The groundwater monitoring program frequency was decreased to an annual event in 2008. Data presented in this report will be used for assessment of remedial actions for OUs 6 and 7. During the April 2017 sampling event, surface water sampling activities at the creeks adjacent to OU 6 and OU 7 were also performed to monitor the presence of VOCs.

OU 6 is the impacted groundwater beneath and downgradient of the Open Storage Area (OU 1), the Area 50 Landfill (OU 2), and the National Guard Area (OU 3). During the 2017 sampling event, ten VOCs [1,1-Dichloroethane; 1,2-dichloroethane; 1,4-dichlorobenzene (1,4-DCB);

carbon tetrachloride; chlorobenzene; cis-1,2-Dichloroethene (cis-1,2-DCE); dichloromethane;

tetrachloroethene (PCE); trichloroethene (TCE); and vinyl chloride (VC)] were detected above maximum concentration levels (MCLs) in the Upper Water Bearing Unit (WBU). Four VOCs (cis-

1,2-DCE, PCE, TCE, VC) were detected above the MCLs in the Lower WBU. No VOCs were detected above MCLs in the Saprolite WBU.

Emulsified vegetable oil (EVO) was injected into several monitoring wells during 2016, specifically monitoring wells that historically have had the highest concentrations of VOCs.

Monitoring wells that had measurable amounts of EVO present at the time of gauging were not sampled during 2017 because samples with EVO are unable to be analyzed by the analytical laboratory. The purpose of the EVO injections was to provide a carbon source in the aquifer and stimulate degradation of the VOCs in groundwater. The presence of degradation products and the geochemical conditions show that conditions are generally favorable in the Upper and Lower

WBU for natural attenuation of VOCs. The presence of significant plumes of degradation products, such as cis-1,2-DCE and VC indicate that the naturally occurring reductive dechlorination process is currently occurring but is not complete at OU6.

OU 7 is the impacted groundwater beneath and downgradient of the former Fire Training Area

(OU 4) and the Polycyclic Aromatic Hydrocarbon (PAH) Area (OU 13). Impacted groundwater in the Lower WBU extends off-installation approximately south of Kingsland Creek, and impacted groundwater in the Saprolite WBU extends to the installation boundary. During the 2017 sampling event, ten VOCs [1,1,1-tetrachloroethane; 1,1-DCE; 1,2-dichlorobenzne; 1,4-DCB; carbon tetrachloride; chlorobenzene; cis-1,2-DCE; PCE; TCE; and VC] were detected above MCLs in the

Lower WBU. Five VOCs (1,1-DCE; cis-1,2-DCE, PCE; TCE; and VC) were detected above

MCLs in the Saprolite WBU.

The VOCs are present in three distinguishable plumes at OU 7 Lower WBU. Three areas of VOC contamination, corresponding to the locations of the three plumes in the Lower WBU are also present in the Saprolite WBU. Trend analyses for VOCs show variations among units, wells, and compounds, which reflects a complex flow and degradation regime and a relatively short period of time since the EVO injections were completed.

Surface water samples were collected in 2017 at three locations along No Name Creek located in

OU 6, and three locations along Kingsland Creek in OU 7. No VOCs were detected in the creek samples at concentrations above MCLs. These results are similar to the historical surface water results.

1 INTRODUCTION

Arcadis, U.S., Inc. (hereinafter referred to as Arcadis) has prepared this Report to document the activities, procedures, and results of monitoring activities for the Defense Logistics Agency

(DLA) Restoration Program at the Defense Supply Center Richmond (DSCR), hereinafter referred to as the Site, located in Chesterfield County, Virginia. The work was performed in accordance with the scope of work dated June 22, 2015 from the United States (U.S.) Army

Corps of Engineers (USACE) Baltimore District, and all amendments and question and answer sets under the USACE, Baltimore District Contract No. W912DR-13-D-0019, Task Order No.

0005, awarded September 25, 2015.

This report presents the results of the annual groundwater and surface water sampling conducted at the DSCR for the 2017 annual sampling events. A biannual monitoring program was initiated in July 2005 to monitor contaminant concentrations and natural attenuation of volatile organic compounds (VOCs) at Operable Units (OU) 6 and OU 7. The monitoring program was updated to an annual event in 2008. The 2017 monitoring results are presented in this report.

Annual groundwater monitoring is implemented and/or supported by the Draft Work Plan –

Operable Units 6,7, and 8 (Work Plan) (Arcadis 2016a) and the Draft Quality Assurance Project

Plan (QAPP) (Arcadis 2016b). The QAPP contains both field and laboratory standard operating procedures and details the management and presentation of data collected during field sampling.

The Work Plan details the groundwater and surface water sampling activities and well gauging activities at the Site, and provides information on activities, procedures, and metrics by which monitoring, operations & maintenance, and optimization activities for the Defense Logistics

Agency (DLA) Restoration Program are to be conducted for the DSCR.

1.1 Purpose and Objectives

In 2008, groundwater sampling decreased from a biannual to an annual sampling schedule to monitor contaminant concentrations and natural attenuation of VOCs in OUs 6 and 7. Monitoring data presented in this report will be used to evaluate the effectiveness of remedy implementation at OU 6 and OU 7. The monitoring data in this report was also collected to:

• Determine if soil contaminants (VOCs, semi-volatile organic compounds [SVOCs], metals, polycyclic aromatic hydrocarbons [PAHs], pesticides and polycyclic chlorinated biphenyls

[PCBs]) from OUs 1, 2 and 3 have leached into the Upper Water Bearing Unit (WBU) at OU

6 at concentrations above the Maximum Concentration Levels (MCLs);

• Determine if soil contaminants (VOCs, SVOCs, metals, PAHs, pesticides and PCBs) from

OUs 4 and 13 have leached into the Lower WBU at OU 7 at concentrations above the MCLs;

• Determine the current contaminant concentrations and monitored natural attenuation (MNA) parameters in OU 6 and OU 7 WBUs.

• Assess remedy performance and remedy optimization in OU 6 and OU 7.

During the April 2017 sampling event, surface water sampling activities at the creeks adjacent to

OU 6 and OU 7 were performed to monitor the concentrations of VOCs in the creeks.

1.2 Facility Background

The DSCR is a federal installation of approximately 650 acres located in Chesterfield County, Virginia, about 8 miles south of the City of Richmond. The DSCR is a primary field-level activity of the DLA and serves as an inventory control point. The DSCR property is roughly L-shaped and approximately 1-mile-wide (east to west) and 2 miles long (north to south). The southeastern portion currently consists primarily of administrative, operations, maintenance, daycare facilities, and recreational areas. The remaining areas include warehouses, open storage, and light industrial facilities. The areas surrounding the installation are primarily residential and woodland with a lesser proportion of commercial/light industrial property. The installation was activated as the

Richmond Quartermaster depot on 1 January 1942, and in 1996, the installation was renamed as

Defense Supply Center Richmond. The Site location is shown on Figure 1-1.

DSCR was officially placed on the Comprehensive Environmental Response, Compensation and

Liability Act National Priorities List in 1987 due to the presence of VOCs in on-site groundwater, potential off-site migration of VOC-impacted groundwater, and groundwater discharge into surface water. A total of thirteen (13) OUs were defined under the Installation Restoration

Program: OUs 1, 2, 3, 4, 5, 10, 11, 12, and 13 have been characterized for soil contamination; OUs

6, 7, and 8 for groundwater contamination; and a groundwater pump-and-treat remediation system for OU 6 was designated as OU 9. Information pertaining to OUs, other than 6 and 7, are presented in this report solely as they relate to OU 6 and OU 7.

1.3 Operable Unit 6

OU 6 consists of contaminated groundwater beneath and downgradient of the Open Storage Area

(OU 1), the Area 50 Landfill (OU 2) and the National Guard Area (NGA) (OU 3), and is located in the central portion of the Site (Figures 1-2 and 1-3). The Open Area Storage (OU 1) was historically used for the bulk storage of chemical drums, recovery of material from leaking drums, and the repair and/or replacement of damaged drums and storage containers; the Area 50 Landfill

(OU 2) was used for the disposal of waste and construction debris; and, the NGA (OU 3) was used for vehicle maintenance activities associated with the National Guard.

Impacts to groundwater are to the upper WBU and the lower WBU, as well as the saprolite unit that underlies the Site. Saprolite is weathered Petersburg Granite bedrock that lies beneath the coastal plain sediments. Primary constituents of concern (COCs) associated with the upper WBU in the OU 6 area are chlorinated VOCs (CVOC), naphthalene, and toluene with concentrations in excess of applicable USEPA MCLs. Groundwater in the lower WBU has concentrations of

CVOCs, 1,4-dioxane, bis (2-ethylhexyl) phthalate, and 3- & 4-methyl phenol. Groundwater is sampled annually to monitor natural attenuation.

An interim remedial action, designated as OU 9, was conducted at the DSCR that included the extraction and treatment of Upper and Lower WBU groundwater for approximately nine years beginning in 1996. The OU 9 treatment system underwent an effectiveness evaluation and the system was placed in a standby status in January 2006. The effectiveness evaluation led to the decommissioning of the OU 9 system in 2008.

During previous investigations and monitoring events, several constituents in the Upper and Lower

WBUs exceeded action levels specified in the OU 9 Record of Decision (ROD) (Law 1993). These constituents included tetrachloroethene (PCE); trichloroethene (TCE); 1,1-dichloroethene (1,1-

DCE); 1,2-dichloroethane; 1,4-dichlorobenzene (1,4-DCB); chlorobenzene; and breakdown products cis-1,2-dichloroethene (cis-1,2-DCE) and vinyl chloride (VC). Constituents exceeding

United States Environmental Protection Agency (USEPA) Region 3 Risk Based Concentrations

(USEPA 2006) included methyl tert-butyl ether and naphthalene. Fuel-related VOCs were also detected in some wells. Low-level (below MCLs) VOC constituents were also detected in OU 6

Saprolite wells during previous investigations. In 2007, enhanced in-situ biodegradation treatability tests were implemented in the OU 2 and OU 3 portions of the OU 6 plumes. These tests consisted of injection of edible oil emulsion in the Upper and Lower WBU to enhance natural degradation (attenuation) of the chlorinated solvent contamination. In 2009, an additional VOC groundwater plume was delineated in the northern portion of the OU6 area. The source of this plume appeared to be in the OU 1 area of the installation. A ROD for OU 6 was signed in

September 2013. The final remedy for OU 6 consists of in-situ bioremediation (ISB), MNA and

Long-Term Monitoring (LTM) and Institutional Controls. (AECOM 2014)

In 2015, ISB was conducted to remediate COCs in groundwater. ISB consisted of injections of emulsified vegetable oil (EVO) in select wells, and was implemented in source areas and downgradient portions of the plumes where concentrations of COCs were the highest and MNA was not progressing at a sufficient rate to limit off site migration. Injections of EVO were completed in July 2015 and OU 6 upper WBU groundwater were monitored quarterly for one year

(AECOM 2016b).

Annual LTM of groundwater is to be conducted for a minimum of five years (beginning in 2013) to monitor for the potential leaching of contaminants from soils. COCs to be monitored as part of

LTM include SVOCs, PAHs, PCBs, pesticides, metals and 1,4-dioxane.

1.4 Operable Unit 7

OU 7 is located in the south-central portion of the installation and encompasses the impacted groundwater beneath and downgradient of the Fire Training Area (FTA) (OU 4) and the PAH Area

(OU 13) (Figure 1-1). The area historically contained three unlined pits that had flammable liquid chemicals and petroleum products dumped into them, ignited, and extinguished as part of fire training activities. Oils, solvents, pesticides and herbicides may have been used as fuel (Law

1993). OU 7 is shown on Figure 1-3.

In accordance with the 2006 DSCR conceptual site model, the OU 7 WBU formerly termed Upper is now designated as Lower, while the former Lower WBU is now designated as the Saprolite

WBU (MACTEC, 2006b). Impacted groundwater in the Lower WBU (formerly the Upper WBU) extends off the installation towards Kingsland Creek.

During previous investigations, constituents detected in the Lower and Saprolite WBUs above

MCLs include PCE; TCE; cis-1,2-DCE; VC; 1,1,1-TCA; 1,1-DCE; chlorobenzene, 1,2-dichlorobenzene, 1,4-DCB; and carbon tetrachloride. Fuel-related VOCs were detected in some wells. In 2007, enhanced in-situ biodegradation treatability tests were implemented in the Pits 1 and 2 areas of the OU 7 Lower WBU. These tests consisted of placement of permeable organic biowalls for the promotion of natural degradation (attenuation) of the chlorinated solvent contamination. Edible oil injections were also performed in one area (Pit 3) of OU 7 groundwater contamination. A ROD for OU 7 was signed in 2012. The final remedy for OU 7 consists of ISB, MNA and LTM and Institutional Controls.

Primary COCs in groundwater include carbon tetrachloride, 1,1-DCE, cis-1,2-DCE, trans-1,2-

DCE, chlorobenzene, PCE, TCE, vinyl chloride, 1,2-dichlorobenzene, 1,4-dichlorobenzene, and chloroform. Annual LTM of groundwater is to be conducted for a minimum of five years

(beginning in 2013) to monitor for the potential leaching of contaminants from OU4 and OU13 soils. COCs to be monitored as part of LTM include SVOCs, PAHs, PCBs, pesticides, metals and

2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD).

1.5 Surface Water – OU6 and OU7

Surface water and sediment samples were collected in the creeks adjacent to the installation as part of a 3-year monitoring program (MACTEC, 2006a). A Human Health Baseline Risk Assessment

(HHBRA) was also completed to evaluate the human health risks (MACTEC, 2006b). Based on the results of the 3-year monitoring program and the HHBRA, and to monitor potential migration of VOCs from groundwater to surface water, DSCR Planning Team members ([DLA], USEPA and Virginia Department of Environmental Quality) along with Air Force Civil Engineer Center, who was working on behalf of DLA, decided to perform annual surface water monitoring activities at No Name Creek (near OU 6) and Kingsland Creek (near OU7) for VOCs only to evaluate impacts to the creeks from the OUs 6 and 7 groundwater contamination. Surface water quality is monitored for VOCs annually in three locations in each of the two creeks to confirm impacts in the upper WBU are not discharging to surface water. (AECOM 2010).

Figure 1-1: Defense Supply Center Richmond Operable Units

Figure 1-2: Operable Unit 6

Figure 1-3: Operable Unit 7

2 FIELD ACTIVITIES

Annual groundwater monitoring was completed in April2017 and activities were performed according to the project planning documents (Arcadis 2016a and Arcadis 2016b). Field activities included static groundwater elevation measurements, groundwater sampling, surface water sampling and purge water containment and disposal. A discussion of each field activity is presented below.

2.1 Groundwater Elevation Measurements

Static groundwater level measurements were collected prior to groundwater sampling activities from 104 monitoring wells selected for sampling at OU 6 and included 72 Upper WBU wells, 30

Lower WBU wells, and 2 Saprolite WBU wells. A total of 102 monitoring wells at OU 7, which included 86 Lower WBU wells and 15 Saprolite WBU wells, had static groundwater level measurements collected prior to groundwater sampling activities. Depth to groundwater measurements were collected from the top of casing of each well using an electronic water level meter. Respective groundwater elevations were then calculated based on the most recent survey data for the top of casing for each well. Depth to groundwater measurements, top of casing elevations, and groundwater elevations for each well included in the annual groundwater monitoring program for OU 6 and OU 7 are presented in Tables 2-1 and 2-2, respectively.

2.2 Sampling and Analysis Activities

Annual groundwater sampling activities included the collection of groundwater samples from monitoring wells selected for analysis. Select monitoring wells for both OU 6 and OU 7 have been outlined in the Work Plan (Arcadis 2016a) and are presented on Table 2-1 and Table 2-2, respectively. The sampling and analysis activities for the April2017 annual event included collection of groundwater and surface water samples for field analysis and laboratory analyses.

Field analysis was conducted using a Hach DR2800 spectrophotometer.

A total of 73 groundwater samples were collected from 65 monitoring wells at OU 6 (including 8 duplicate samples) and a total of 106 groundwater samples were collected from 95 monitoring wells and piezometers at OU 7 (including 11 duplicate samples) from April 06 – 13, 2017 as outlined below: The number of wells monitored consisted of the following:

OU 6 – 73 Samples

• 41 Upper WBU wells (4 duplicates)

• 22 Lower WBU wells (3 duplicates)

• 2 Saprolite WBU wells (1 duplicate)

OU 7 – 106 Samples

• 81 Lower WBU wells (10 duplicates)

• 14 Saprolite WBU wells (1 duplicates)

In addition, 3 surface water samples were collected from No Name Creek (adjacent to OU 6) and

3 surface water samples were collected from Kingsland Creek (adjacent to OU 7).

Three Upper WBU monitoring wells at OU 6 (OU6-MW-29, OU6-MW-120 and OU6-MW-122) that had previously been damaged were replaced between April 22 – 24, 2015. Replacement monitoring wells include OU6-MW-226, OU6-MW-223, and OU6-MW-222 respective to the previously mentioned monitoring wells.

Monitoring well locations at OU 6 are shown on Figures 2-1 and monitoring well locations in OU

7 are shown on Figure 2-2. Surface water sample locations are also shown on Figures 2-1 and 2-

2.

2.2.1 Low Flow Groundwater Sampling

Groundwater samples were collected in accordance with USEPA recommended low-flow groundwater sampling procedures and in accordance with the installation QAPP (Arcadis 2016b).

This method produces minimal well drawdown and minimizes loss of VOCs during sampling as well as produces less volume of investigation derived waste (IDW). Larger diameter (> 2” diameter) wells with depth to water measurements greater than approximately 18 feet were sampled using a Proactive® SS Monsoon submersible pump with a control unit that allowed regulation of the groundwater flow rate and disposable 3/8-inch tubing. Smaller diameter wells were sampled using Geotech Geopump II® peristaltic pumps and dedicated Teflon-lined 0.175-inch polyethylene tubing. In instances where practical, tubing was secured in the monitoring well for future use. During groundwater sampling, field parameters were measured using Horiba® U52

(or equivalent) water quality meters that were calibrated at the beginning of each day, and as needed where necessary. The following field parameters were recorded:

• pH

• Specific conductivity

• Oxidation-reduction potential (ORP)

• Temperature

• Dissolved oxygen (DO)

• Turbidity

• Drawdown (depth to water measurements)

Groundwater samples for field tests and laboratory analyses were collected after stabilization and a turbidity of less than 20 NTUs was achieved. Stabilization was defined as three successive readings within 0.3 for temperature, 0.1 for pH, 10 millivolts for ORP, 3 percent for conductivity, and 10 percent for DO and turbidity. Monitoring well sampling forms are presented in Appendix A1 and field notes are provided in Appendix A2.

Turbidity readings of less than 20 NTUs could not be achieved after substantial pumping in some wells despite using low-flow sampling techniques. For these wells, each well was pumped to achieve the lowest possible stabilized turbidity reading and groundwater samples were collected after three successive stabilized readings.

Groundwater samples were collected, preserved, packaged, and shipped in accordance with the installation QAPP (Arcadis 2016b). Chain-of-custody records were included with each shipment of sample coolers to the off-site analytical laboratory and are presented as Appendix A3.

Groundwater samples were analyzed for several parameters as discussed below.

All OU 6 and OU 7 monitoring wells were analyzed for:

• VOCs (SW8260B);

• Anions [chloride and sulfate] (SW9056);

• Dissolved gases [ethane, ethene and methane] (EPA Method RSK175)

• Total Organic Carbon (SW9060).

Five Upper WBU monitoring wells at OU 6 and six Lower WBU monitoring wells in OU 7 were analyzed for:

• SVOCs (SW8270D)

• Total metals (SW6010C/SW7470A)

• PAHs – low level SVOCs (8270D)

• Pesticides (8081B)

• PCBs (8082A)

One Upper WBU monitoring well and eight Lower WBU monitoring wells at OU 6 were analyzed for:

• 1,4-Dioxane and bis (2-ethylhexyl) phthalate (SW8290)

Four Lower WBU wells at OU7 were also analyzed for:

• 2, 3, 7, 8-TCDD (SW8290)

An on-site spectrophotometer (Hach Model DR2800) was utilized to analyze for the following field parameters:

• Ferrous Iron (Method 8146)

• Nitrate/Nitrite (Method 10020)

• Sulfate/Sulfide (Method 8051)

• Manganese (Method 8034)

• Alkalinity (as CaCO3) (Method 10239)

2.2.2 Surface Water Sampling

Surface water samples were collected by using a clean surface water sampling dipper cup, which is constructed of a sampling cup at the end of an extendable rod. Prior to sample collection, one set of surface water field parameters (temperature, specific conductance, pH, DO, turbidity and

ORP) were recorded on the sampling forms. These forms are presented in Appendix A4.

2.3 Monitoring Well Inventory and Inspection

An inventory of all monitoring wells sampled in each OU was conducted prior to the groundwater sampling activities. The well inventory and inspection was conducted to determine if all wells in each OU were accounted for, properly identified, and in good condition. One monitoring well was unable to be located (OU6-MW-181). Reasonable attempts were made to locate the well including available northing and easting data and global positioning systems.

The following conditions were inspected during the inventory:

• Surface Completion

• Well Seal

• Well Cap

• Lock

• Well Monument/Labeling

2.4 Investigation-Derived Waste Management and Disposal

IDW was containerized and sampled for waste characterization. IDW generated during the April

2017 field activities consisted of purge water from sampling activities and decontamination fluids.

IDW was containerized in 500-gallon poly tanks and labeled for subsequent off-site disposal. The

IDW disposal was conducted in accordance with the planning documents and DLA directives.

Appendix A5 presents the IDW disposal documentation.

Figure 2-1: OU 6 Monitoring Well and Surface Water Sample Locations

Figure 2-2: OU 7 Monitoring Well and Surface Water Sample Locations

Table 2-1: OU 6 Monitoring Well Construction Details and Groundwater Elevation Data

Table 2-2: OU 7 Monitoring Well Construction Details and Groundwater Elevation Data

Table 2-3: OU 6 Groundwater Sampling and Analysis Plan

Table 2-4: OU 7 Groundwater Sampling and Analysis Plan

3 VARIANCES/NON-CONFORMANCES

During the April 2017 sampling event, EVO remained in 42 monitoring wells in OU 6 (30 Upper

WBU monitoring wells and 12 Lower WBU monitoring wells). Of the 42 monitoring wells, 38 monitoring wells had received EVO injections (pressure and/or gravity feed) as described in the

Final Technical Memorandum Remedial Design/Remedial Action Work Plan Addendum

Operable Unit 6 (AECOM 2016). Four of the monitoring wells that had EVO during groundwater sampling, but were not identified as injection wells, are located in the vicinity of monitoring wells that had received EVO injections. Groundwater samples were not collected from monitoring wells that had measurable amounts of EVO in 2017.

Additionally, OU6-MW-181 was unable to be located (Section 2.3); therefore, it was not sampled.

4 RESULTS AND RECOMMENDATIONS

This section discusses groundwater flow and groundwater and surface water analytical results.

The potentiometric surface maps were developed based on the groundwater elevation data in

Tables 2-1 and 2-2. Groundwater and surface water analytical results are summarized in Tables

4-1 through 4-20. Groundwater collection records and field documentation is provided as

Appendix A and the laboratory analytical reports are also included in Appendix B. Potentiometric surface maps and contaminant concentration contour maps are shown in Figures 4-1 through 4-32.

Data validation reports are presented as Appendix C. An analysis of trends for VOCs at selected monitoring wells is presented in Appendix D, and only includes monitoring wells that did not have

EVO in the monitoring well at the time of sampling.

4.1 Operable Unit 6

4.1.1 Groundwater Flow

Figure 4-1 indicates groundwater in the Upper WBU flows east across the Site. Figure 4-2 indicates that groundwater in the Lower WBU flows predominantly east across the site. Only two wells were gauged from the Saprolite WBU, therefore a potentiometric surface elevation map was not generated for that WBU.

4.1.2 Analytical Results

VOC and SVOC constituents, and MNA parameter concentrations in Upper, Lower and Saprolite

WBUs at OU 6 are summarized in Tables 4-1 through 4-8. Additionally, 1,4-dioxane and bis(2-ethylhexyl)phthalate was analyzed in select OU 6 Lower WBU well samples (Table 4-7).

Concentrations have been compared to MCL detailed on the USEPA Regional Screening Levels

(RSLs) Summary Table - June 2017. Concentrations that exceeded the respective MCLs are shaded gray. For analytes with detectable concentrations, the concentration is bolded.

4.1.2.1 Upper WBU Wells

Table 4-1 summarizes the VOC analytical results for OU 6 Upper WBU monitoring wells. Nine

VOCs were detected in OU 6 Upper WBU wells at concentrations exceeding respective MCLs.

Monitoring wells that historically have had the highest concentrations of COCs had been selected to receive EVO injections as outlined in the Final Technical Memorandum: Remedial

Design/Remedial Action Work Plan Addendum Operable Unit 6 (AECOM 2016a) and the Draft

Injection Summary Technical Memorandum, Operable Unit 6 (AECOM 2016b). Exceedances of

VOCs respective to MCLs included:

• 1,2-Dichloroethane (3 samples between 6.08 D and 24.6 D micrograms per liter (µg/L))

• 1,4-Dichlorobenzene (2 sample at 79.6 D and 316 D µg/L)

• Carbon Tetrachloride (1 sample at 8.30D µg/L)

• Chlorobenzene (2 samples 104 D and 392 D µg/L)

• Cis-1,2-DCE (9 samples between 71.0 D and 1950 D µg/L, including one duplicate sample)

• Dichloromethane (1 sample at 24.6 D µg/L)

• PCE (8 samples between 13.40 D and 75.8 D µg/L, include one duplicate sample)

• TCE (17 samples between 8.66 D and 226 D µg/L, including two duplicate samples)

• VC (8 samples between 2.29 J and 126 D µg/L)

Figures 4-3 through 4-7 show the extent of the PCE, TCE, cis 1,2-DCE and VC plumes in the

Upper WBU at OU 6. Figure 4-8 presents the locations that had detections of COCs that exceeded respective MCLs. Based on historical and 2016 monitoring data, two separate contaminated areas exist in the OU 6 Upper WBU. The first area, the northern plume, is located around the northwest corner of OU 2 (near Building 54) and primarily consists of chlorinated ethene contamination.

The source area for this northern plume appears to be located underneath OU 1, which is known as the Open Storage Area.

The source area for the southern plume is located in the southern portion of OU 6, which is the location of the OU 2 landfill. Groundwater contaminants in this area consists of chlorinated ethenes, chlorinated ethanes, and chlorobenzenes. The contaminant plume from this area appears to migrate to the east under Building 151. Based on historical groundwater contaminant data and previous investigations, the area to the east of Building 151 also contributes to this southern groundwater contaminant plume.

The overall PCE footprint of the northern plume appears to have decreased in size since 2016, however the extent of TCE, cis-1,2-DCE and VC have remained fairly consistent. The 2017 results indicate that the southern plume appears to be decreasing in size, particularly in the vicinity of OU

2. A review of the 2017 monitoring data for the OU6 Upper WBU is presented below.

OU6 Upper WBU Northern Plume

In 2015, the highest concentrations of PCE was observed in OU6-MW-127 at a concentration of

5,500 µg/L. EVO injections were completed between July and August 2015, and select monitoring wells received additional EVO injections in December 2015, and March/April 2016. Select monitoring wells that received EVO injections are included in the Draft Injection Summary

Technical Memorandum(s) (AECOM 2016b and AECOM 2016c). Monitoring wells that received

EVO injections includes monitoring wells that have historically had the highest concentrations of

PCE. Below is a summary of monitoring wells located in the northern plume that received EVO injections and continued to exhibit measurable amounts of EVO:

• OU6-MW-87 – Gravity Feed Injection (December 2015, March/April 2016)

• OU6-MW-90 – Gravity Feed Injection (December 2015, March/April 2016)

• OU6-MW-112 - Gravity Feed Injection (December 2015, March/April 2016)

• OU6-MW-123 – Gravity Feed Injection (December 2015, March/April 2016)

• OU6-MW-125 – Gravity Feed Injection (December 2015, March/April 2016)

• OU6-MW-127 – Gravity Feed Injection (December 2015, March/April 2016)

• OU6-MW-128 – Gravity Feed Injection (December 2015, March/April 2016)

• OU6-MW-132 – Gravity Feed Injection (December 2015, March/April 2016)

• OU6-MW-179 – Gravity Feed Injection (December 2015, March/April 2016)

These monitoring wells have historically represented the highest concentrations of COCs in the northern plume. Due to the presence of EVO at the time of sampling, the groundwater samples were not collected from these monitoring wells.

In April 2017, the highest PCE concentration detected in the northern plume was in OU6-MW-88 at a concentration of 75.8 D µg/L. The highest TCE concentration was detected in monitoring well OU6-MW-130 (226 D µg/L), which is an increase from the 2017 concentration of 127 µg/L.

The highest concentration of cis-1,2-DCE was detected at a concentration of 1,950 D µg/L in OU6-

MW-115 and the highest concentration of VC was detected in OU6-MW-72 at 126 D µg/L.

A significant cis-1,2-DCE plume combined with the occurrence of VC in only three wells in the northern plume indicates that naturally occurring dechlorination processes are occurring in this area. This is supported by the presence of ethene in select wells, and methane across the OU 1 plume. TOC ranges for the monitoring wells within the northern plume range between ND to 24 mg/L (MW-134).

OU 6 Upper WBU Southern Plume

As previously stated, the source of the southern plume is the OU 2 landfill. The highest PCE detection in the southern plume during the 2016 groundwater sampling event was 12.9 µg/L in

OU6-MW-66, however this monitoring well location was not sampled during 2017. Historically, the southern PCE plume has centered around well OU6-MW-69. OU6-MW-69 was utilized as an

EVO injection well in December 2015 (AECOM 2016), and was not sampled during 2017.

Below is a summary of monitoring wells located in the southern plume that either received EVO injections, or had EVO in the monitoring well at the time of sampling:

• OU6-MW-45 – Gravity Feed Injection (December 2015, March/April 2016)

• OU6-MW-52 – Gravity Feed Injection (December 2015, March/April 2016)

• OU6-MW-60 – Gravity Feed Injection (December 2015, March/April 2016)

• OU6-MW-62 – EVO present in well at time of sampling – not an injection location

• OU6-MW-66 – Gravity Feed Injection (December 2015, March/April 2016)

• OU6-MW-67 – Gravity Feed Injection (December 2015, March/April 2016)

• OU6-MW-69 – Gravity Feed Injection (December 2015, March/April 2016)

• OU6-MW-79 – Gravity Feed Injection (December 2015, March/April 2016)

• OU6-MW-82 – EVO present in well at time of sampling – not an injection location

• OU6-MW-85 – Gravity Feed Injection (December 2015, March/April 2016)

• OU6-MW-150 – Gravity Feed Injection (December 2015, March/April 2016)

• AEHA-14A – Gravity Feed Injection (July/August 2015)

• AEHA-27A – EVO present in well at time of sampling – not an injection location.

• AEHA-28A – Gravity Feed Injection (December 2015, March/April 2016)

• AEHA-29A – Gravity Feed Injection (December 2015, March/April 2016)

• MWNGA-1 – Gravity Feed Injection (December 2015, March/April 2016)

• PZ-1 – Gravity Feed Injection (December 2015, March/April 2016)

PCE was not detected in the area of the OU 2 landfill plume area during 2017 at concentrations that exceeded the MCL. The highest concentration of PCE was detected in OU6-MW-65 at a concentration of 4.13 µg/L (Figure 4-4), which is below the MCL of 5 µg/L.

The highest TCE concentration was detected in OU6-MW-72 at 51.0 µg/L in 2017 (Figure 4-5), which is a slight decrease from 59.4 µg/L in 2016. Historically, the highest concentration of TCE has been observed in OU6-MW-69 which is located in the center of the plume of OU 2 landfill, however as previously stated OU6-MW-69 was not sampled in 2017 and was utilized as an EVO injection location in December 2015. The highest concentration of cis-1,2-DCE was detected in

OU6-MW-60 at a concentration of 1,210 µg/L and concentrations of cis-1,2-DCE were also detected at concentrations that ranged between 270 µg/L (OU6-MW-84) and 488 µg/L (OU6-MW-

72) (Figure 4-6). VC was detected at a concentration of 64.8 µg/L (OU6-MW-226) in the OU 2 source, and VC ranged in between 126 µg/L (OU6-MW-72) and 65.8 µg/L (OU6-MW-84) (Figure

4-7). The presence of daughter products indicates that dechlorination is occurring in these areas.

Concentrations of ethene and ethane present in the OU 2 source area as well as downgradient in the vicinity of historical EVO injections supports that naturally occurring dechlorination processes are occurring in these areas. Concentrations of TOC ranged between <2.50 mg/L in several monitoring wells to 4,610 mg/L in OU6-MW-60. The presence of these concentrations indicates that conditions are supportive of degradation in areas in the vicinity of the historical EVO injections, however concentrations of TOC have decreased overall since 2016 indicating that TOC concentrations are not sufficient to maintain ongoing degradation. Generally, TOC concentrations are low throughout the Upper WBU southern plume area, and concentrations of TOC ranged between 1.60 mg/L (OU6-MW-68) and 8.04 mg/L (OU6-MW-158) in areas not influenced by historical EVO injections (Table 4-4).

4.1.2.2 Lower WBU Wells

Table 4-2 summarizes the analytical results for groundwater samples collected from the Lower

WBU wells at OU 6. Five VOCs were detected in OU 6 Lower WBU groundwater at concentrations exceeding MCLs. These VOCs included:

• 1,1-Dichloroethene (1 sample at 8.36J µg/L)

• cis-1,2-DCE (2 samples at 70.8 D and 206 D µg/L)

• PCE (3 samples at 12.5 and 5.58 µg/L)

• TCE (6 samples at 10.7 to 125 µg/L)

• VC (5 samples at 2.35 to 41.0 µg/L

Figures 4-10 shows a total VOC contour map of the Lower WBU that depicts the general extent of the COC plume(s), and Figures 4-11 through 4-14 show the extent of PCE, TCE, cis-1,2 DCE and VC plumes in the Lower WBU at OU 6. A review of the 2017 monitoring data for the OU6

Lower WBU is presented below. Figures 4-15 depicts monitoring wells with concentrations of

COCs that exceed MCLs for COCs with minimal detection frequency. Figure 4-16 shows the extent of ethene, ethane and methane.

OU6 Lower WBU Northern Plume

Figure 4-11 shows sporadic detections of PCE above the MCL with a small plume present around well DMW-34B, and an isolated occurrence slightly above the MCL at well OU6-MW-171. At well DMW-34B, PCE concentrations increased slightly from 5.92 µg/L in 2015 to 7.30 µg/L in

2016 to 12.5 µg/L in 2017. A second isolated plume was detected at OU6-MW-171 (5.58 µg/L) which is a slight increase from 2016 where it was detected at a 5.07 µg/L. Historically, TCE has been detected at OU6-MW-217 and AEHA-31B, however both monitoring wells were utilized as

EVO injection locations and were not sampled during 2017 due to the presence of EVO in the monitoring wells at the time of gauging.

As shown in Figure 4-12, a TCE plume is located in the OU 1 area with the highest concentrations detected in monitoring wells OU6-MW-160 (13 µg/L), OU6-MW-165 (18 µg/L) and OU6-MW-

166 (26 µg/L), consistent with the Upper WBU source area at this location. Historically, the highest TCE concentration in the plume area has been detected in OU6-MW-159 however this monitoring well location was utilized as an EVO injection location and was not sampled during

2017 due to the presence of EVO at the time of gauging. Additional monitoring wells utilized as

EVO injection locations are detailed below:

• OU6-MW-159 – Gravity Feed Injection (December 2015, March/April 2016)

• OU6-MW-170 – Gravity Feed Injection (December 2015, March/April 2016)

A second isolated TCE plume is located around monitoring well DMW-34B with a TCE concentration of 5.70 µg/L in 2017. Cis-1,2-DCE, VC, and TOC were not detected in this monitoring well. VC has previously been detected DMW-34B (0.445 J µg/L in 2016) indicating that naturally occurring reductive dechlorination has either slowed down or stalled in northern area in the lower WBU northern plume.

OU6 Lower WBU Southern Plume

Historically, isolated occurrences of PCE at low levels were observed in wells AEHA-31B and

OU6-MW-216 (EBF-02D) (Figure 4-11); however, PCE was not detected in any monitoring wells in the Lower WBU southern plume during 2017. Monitoring wells that have had detectable concentrations of PCE were used as EVO injection locations and had measurable amounts of EVO present in the monitoring well at the time of sampling. Monitoring wells that had measurable amounts of EVO in the monitoring well at the time of gauging were not sampled during 2017.

Below is a detailed summary of monitoring wells that were used as EVO injection wells:

• AEHA-27B – Pressure Injection (July/August 2015)

• AEHA-28B – Pressure/Gravity Feed Injection (December 2015, March/April 2016)

• AEHA-29B – Pressure/Gravity Feed Injection (December 2015, March/April 2016)

• AEHA-31B – Pressure Injection (July/August 2015)

• OU6-MW-216/EBF-02D – Gravity Feed Injection (December 2015, March/April 2016)

• OU6-MW-217/EBF-04D – Gravity Feed Injection (December 2015, March/April 2016)

• OU6-MW-146 – Gravity Feed Injection (December 2015, March/April 2016)

• OU6-MW-147 – Gravity Feed Injection (December 2015, March/April 2016)

• OU6-MW-148 – Gravity Feed Injection (December 2015, March/April 2016)

• OU6-MW-151 – Gravity Feed Injection (December 2015, March/April 2016)

Four separate TCE plumes were detected in the Lower WBU at OU 6. The highest concentration of TCE detected in 2017 was in monitoring well OU6-MW-94 (99 µg/L) which is located in the

OU 3 area extending off-installation into the wooded area east of OU 3. TCE concentrations and respective isoconcentration contours are depicted on Figure 4-12. Historically, the highest concentration of TCE has been detected in EBF-02D (replaced by OU6-MW-216 in 2015);

however, this…