1.1 - Purpose of Report

Between November 1999 and September 2001, 15 groundwater monitoring wells (MW) were installed at Camp Stanley Storage Activity (CSSA) to aid in the horizontal and vertical delineation of solvent contamination in the Middle Trinity Aquifer.� This report describes the field methods, results, conclusions, and recommendations associated with the well installation activities.

1.2 - Project Authorization

Installation of 12 monitoring wells was authorized under Air Mobility Command (AMC) Contract F11623-94-D-0024, Delivery Order (DO) RL83, and installation of three wells was authorized under Air Force Center for Environmental Excellence (AFCEE) Contract F41624-94-D-8136, DO 23.� This work was conducted by Parsons under the technical supervision of AFCEE and has also been overseen by the U.S. Environmental Protection Agency (EPA) Region VI Resource Conservation and Recovery Act (RCRA) Enforcement Section since October 1993.

This report summarizes work associated with the new well installations under DOs 23 and RL83.� Limited interpretation of data collected during installation of the wells, including those based on packer test results and discrete-interval sampling, is presented in this report.� Further interpretation of the CSSA well data collected under RL83 and DO23, integrated with data collected from other wells at CSSA and regional information, will be presented in the Conceptual Site Model (CSM) Report currently being prepared.

1.3 - Regulatory Basis

As a Department of Defense entity, CSSA is subject to federal and state environmental laws.� Specifically, the Safe Drinking Water Act (SDWA) applies to wells that serve at least 25 people or connections.� In 1991, CSSA operated five wells subject to SDWA requirements (CS-1, CS-9, CS-10, CS-11, and CS-16).� During that time, groundwater contamination was detected in Well CS-16, and under Section 120 of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), CSSA was obliged to characterize and remediate the groundwater contamination.� In addition, 40 Code of Federal Regulations (CFR) Part 260, promulgated under RCRA, establishes requirements and standards for groundwater protection.� Upon verification of solvent contamination in Well CS-16 on August 23, 1991, CSSA deactivated Well CS-16 and notified water users of the contamination issue, as required by state and federal regulations.� CSSA then initiated groundwater investigations, including installation of wells described in this report.

In January 1993, preliminary investigation data were presented to the Texas Department of Health (TDH), Texas Natural Resource Conservation Commission (TNRCC, currently known as the Texas Commission on Environmental Quality [TCEQ]), and EPA Region VI RCRA Permitting Section at a technical interchange meeting.� The project plans of actions were submitted to EPA and TCEQ (formerly the TNRCC) in May 1993.�

On June 30, 1993, the EPA notified CSSA that an Administrative Order on Consent would be issued to CSSA.� This consent order, issued under Section 3008(h) of RCRA on May 5, 1999, requires CSSA to investigate groundwater contamination, as well as solid waste management units (SWMU) and areas of concern (AOC) at the facility.� Groundwater investigations conducted at CSSA, including the well installation described in this report, are done in accordance with requirements of the consent order.

On October 19-20, 1995, a regulatory meeting was held with the EPA and the TCEQ to discuss the status of investigations completed to date.� The actions reviewed included groundwater monitoring results, borehole geophysical surveys in existing wells, surface geophysics performed at potential source areas, soil gas survey results, geologic mapping, and RFI activities conducted at SWMUs.� Based on regulatory review of the data, proposed future actions included additional soil gas surveys, extended geologic mapping, and continuing groundwater monitoring.� Finally, discussions regarding source removal actions at SWMUs O-1 and B-3 were encouraged to alleviate future groundwater contamination.� Once the continuing source areas had been treated, the groundwater plume delineation and potential remedial activities were to be addressed with an aggressive drilling program.

1.4 - Groundwater Investigation Chronology

Contaminants were initially detected in CSSA Well CS-16, shown in Figure 1.1, during routine water supply testing in 1991.� Groundwater withdrawals at CS-16 ceased immediately.� Confirmation sampling showed concentrations of tetrachloroethene (PCE) and trichloroethene (TCE) above drinking water maximum contaminant levels (MCL) and the well was taken out of service.� A comprehensive investigation of groundwater contamination at CSSA began in 1992.� The effort started with preliminary evaluations to establish the extent of the problem without invasive field techniques, namely analyzing groundwater samples from existing CSSA wells and conducting geophysical surveys to identify potential contamination source areas.� Samples from Well CS-D, located approximately 250 feet west of Well CS-16, also exhibited concentrations of PCE and TCE that exceeded MCLs.� Camera surveys were also performed at CSSA wells to inspect the integrity of existing casings and document general conditions inside the wells.� Following this effort, the Hydrogeologic Report for Evaluation of Groundwater Contamination (ES, 1993) was submitted to the appropriate regulatory agencies for comment and approval.�

A groundwater monitoring and reporting program was initiated in 1994.� Attempts to identify specific contaminated zones in several CSSA wells through discrete groundwater sampling proved inconclusive.� Nevertheless, after reviewing geophysical and video logs, surface casing was installed to 200 feet below ground surface (bgs) in Wells CS-2, CS-3, CS-4, CS-16, and CS-D to seal off shallow water-bearing zones that may have been contributing to migration of volatile organic compound (VOC) contamination through the open boreholes.� Investigation activities continued in 1995, including additional downhole geophysical logging, discrete interval sampling, and well upgrades.� In addition, monitoring of three off-post domestic water supply wells was initiated in 1995.� At that time, none of the off-post wells that were sampled showed evidence of contamination.

Work in 1995 relating to groundwater contamination issues focused on source characterization.� To help identify potential contamination source areas, historical records were examined and interviews with CSSA employees were conducted.� This resulted in the location of numerous SWMUs and other AOCs.� Sites were examined throughout CSSA where waste had been dumped and/or burned during past disposal activities.� Areas showing unusual topography were also considered to be possible waste burial locations.� Electromagnetic and ground penetrating radar surveys were conducted at some of these sites in early 1995, followed by soil-gas surveys in areas of the geophysical anomalies.� Subsequently, SWMU B-3 and the abandoned oxidation pond SWMU O-1, located in the northeast corner of the Inner Cantonment, were identified.� The pond once held waste fluids and sludge from CSSA's weapons bluing operations.� The pond was abandoned and filled in 1985.� At B-3 there had been a wide trench where solid and liquid waste was apparently burned.� The trench was backfilled sometime around 1990.� Additional geophysical surveys, soil gas sampling, soil boring, and sampling continued at CSSA.� Results indicated that SWMUs B-3 and O-1 contained significantly higher concentrations of VOC contaminants than other sites.� Analytical results showed PCE in SWMU O-1 soil samples and PCE, TCE, and dichloroethene (DCE) in soil at SWMU B-3.� Results of these investigations are provided in the Technical Memorandum on Soil Boring Investigations (Parsons ES, 1995b), the Technical Memorandum on Surface Geophysical Surveys at High Priority Sites (Parsons ES, 1995c), and the Technical Memorandum on Surface Geophysical Surveys, Well 16 Source Characterization (Parsons ES, 1995a).

Other activities completed by Parsons around this time included mapping of two fault zones crossing through CSSA.� One narrow fault zone courses through the southern portion of CSSA trending southwest to northeast.� A second, wider fault zone bisects CSSA immediately south of CS-16, trending roughly west to east.� At an October 1995 meeting involving EPA, TNRCC, AFCEE, and CSSA and its consultants, it was agreed that groundwater work at CSSA would continue to focus on source characterization.� Quarterly groundwater, which included sampling and analysis, continued.

In 1996, CSSA initiated additional source characterization at SWMUs B-3 and O-1 in preparation for source removal.� Additional detailed geophysical work was completed in areas around CS-16 and south to CS-1.� CSSA had two monitoring wells (CS-MW1-LGR and CS-MW2-LGR) installed south of CS-16.� The wells were drilled into the bottom of the Lower Glen Rose (LGR) Formation, with TCE concentrations above MCLs found in both wells.� The Groundwater Investigation and Associated Source Characterization Report (Parsons ES, 1996), which includes source characterizations of SWMUs B-3 and O-1, was submitted to the regulatory agencies.

CSSA began groundwater monitoring using a QED MicroPurge^� Low-Flow system in early 1997.� Camera surveys were completed in CS-1, CS-9, and CS-11, followed by upgrading that included carbon dioxide (CO₂) rehabilitation treatments.� Ongoing work for SWMU and AOC site characterizations did not reveal additional potential sources contributing to the CS-16 area plume.� However, past use of solvents in CSSA Building 90 was suspected as a potential source of contamination in the southwest corner of the post.� From 1998 through the date of this report, CSSA has continued monitoring water levels and conducting groundwater sampling.� Groundwater monitoring reports are included in Volume 5 of the CSSA Environmental Encyclopedia.

In 1998, planning for the installation of several clustered monitoring wells throughout CSSA was initiated.� The intention of the well clusters was to aid in the ongoing characterization of groundwater contamination at CSSA.� The wells provide for monitoring of the major water-bearing zones in the LGR, Bexar Shale (BS) and Cow Creek (CC) portion of the Middle Trinity Aquifer.

Additional cluster wells are currently being installed, and the quarterly groundwater monitoring program continues.� A chronology of work conducted in association with the groundwater investigation is provided in Volume 1-1 of the Environmental Encyclopedia.

1.5 - Objectives and Scope of Investigation

The goals of this investigation are to provide additional data for determining the extent of groundwater contamination at CSSA and to gain a better understanding of the aquifer hydrologic properties.� As described above, well installation efforts were conducted under two delivery orders, and included the following specific objectives:

1. Install three monitoring wells in the LGR Formation (DO23).

2. Install 12 monitoring wells in five clusters, completed in each of three units of the Middle Trinity Aquifer (RL83).

3. Conduct downhole geophysical surveys at each drilling location.

4. Conduct injection packer tests at two intervals in each hydrogeologic zone.

5. Collect core samples for VOCs and metals analyses.

6. Collect a groundwater grab sample from each hydrologic zone for background metals and cation/anion analyses.

7. Conduct fracture analysis of 20 feet of core per borehole.

8. Develop monitoring wells.

9. Survey well locations.

10. Install a low-flow pump in each well.

11. Install transducers in four wells.

12. Handle, sample, and dispose of investigation-derived waste (IDW).

13. Prepare a well installation report.

1.6 - Report Organization

This report is organized in five sections.� Section 1 presents an overview of the report, including the project purpose, regulatory basis, authorization, and the objectives and scope of the well installation work done under RL83 and DO23.� Section 2 contains the methodology used for the well installations.� This includes discussion of the drilling of coreholes and well boreholes, monitoring well construction, surface completions, monitoring well development, geophysical borehole logging, packer tests, well surveying, decontamination procedures, and management of IDW.� A field narrative of events in chronological order is presented in Section 3.� Section 4 describes findings of the groundwater investigation.� Finally, Section 5 contains the report conclusions.� Supporting data and an electronic data CD are included in the appendices.

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