All SWMUs addressed in this portion of the work plan, except B-14, the coal bins, and the high priority SWMUs, will be investigated for comparison to TNRCC Risk Reduction Standard 1 closure criteria. Each site will be investigated to varying degrees based on previous record searches, field investigations, geophysical surveys, and analytical data. For low priority SWMUs, closure is expected to require only a geophysical survey and surface samples to demonstrate that metals of concern are at background levels and that no subsurface disturbance, typical of buried waste, exists at the site. If constituents are discovered to exceed background levels in the surface or if a subsurface anomaly is identified, subsurface sampling will be required to characterize the subsurface environment. Two low priority SWMUs, B-14 and the coal bins, will be delisted based on evidence that they were never used as SWMUs and are not anticipated to need closure under state regulations. Four others (B-5, B-6, B-25, and B-26) could not be field verified during the EA (ES, 1993b) and may not exist. These units will be investigated during field activities as described in Section 2.4.2, but are potentially eligible for delisting as well.

Medium priority SWMUs have generally been identified as sites with a high probability of subsurface disturbance and the corresponding need for subsurface sampling. These thirteen SWMUs are identified as landfills, trenches, dumps, or sites with identified subsurface anomalies. If such a subsurface disturbance is identified or surface samples contain constituents above background, subsurface sampling will be performed as part of closure efforts.

Six high priority SWMUs identified in this work plan will undergo noninvasive investigations including geophysical surveys and soil gas sampling. One high priority SWMU, the oxidation pond (SWMU O-1), may undergo a treatability study for remedial efforts.

Once all data has been collected, the results will be reported to the TNRCC for certification of closure for all appropriate SWMUs. Section 2.5 details closure report content to be submitted to the TNRCC.

The following sections describe the rationale and methodology of the field actions to be performed at each SWMU.

2.1 - Closure Methodology

This section describes the regulatory background regarding SWMU closure, the performance standards which must be met for TNRCC closure certification, and general procedures for closure of the SWMUs under investigation.

2.1.1   Regulatory Background

The Texas Risk Reduction Rules, codified in 30 TAC 335 Subchapter S, establish comprehensive, risk-based standards for closure/remediation of soil, groundwater, surface water, and air contaminant problems. Three alternate levels of environmental remediation referred to as Risk Reduction Standards Nos. 1, 2, and 3, are allowed. For each Risk Reduction Standard, the rules outline relevant requirements for site characterization, media clean-up levels, verification sampling and testing, project documentation, and deed recordation.

Closure of industrial SWMUs subject to these regulations must meet on the following risk reduction standards:

The following section describes the requirements necessary for the closure of the SWMUs located at CSSA under 30 TAC 335 Subchapter S regulations. All of CSSA’s SWMUs identified for closure under this work plan are subject to the regulations described in this section.

The relative requirements for the risk reduction standards are presented in Table 2.1.

2.2 - Closure Procedures

For closure of CSSA’s SWMUs, the principal tasks required for TNRCC approval under Risk Reduction Standards Numbers 1 and 2 are discussed in this section. It is anticipated that all of the SWMUs identified for closure in this portion of the work plan will be submitted for closure under Risk Reduction Standard 1.

For closure under Risk Reduction Standard 1 and 2, no pre-approval is required from the TNRCC to commence closure actions. However, notification of intent to perform closure and estimated schedule must be submitted to the TNRCC as specified in 30 TAC 335.8(c)(1). With support from Parsons ES, CSSA will provide sufficient notice to the TNRCC prior to closure actions.

A remedial investigation is required by Risk Reduction Standards 1 and 2 in order to evaluate the nature and extent of residual waste and affected environmental media. The investigation will also identify contaminants of concern, potential affected media, and exposure pathways.

To obtain closure under Risk Reduction Standard No. 1 any waste residue identified in the remedial investigation of a SWMU must be removed, and the removal or decontamination of affected environmental media must be accomplished. The remedial effort must be accomplished to either background levels or practical quantitation limits (PQLs), whichever is greater. Verification sampling should confirm and demonstrate that compliance with appropriate clean up levels has been attained.

For closure under Risk Reduction Standard No. 2, any waste residue identified in the remedial investigation of a SWMU that is present must be removed, and the removal or decontamination of affected environmental media must be accomplished. The remedial effort must remove residual concentrations of contaminants in the environmental media to health based clean up standards specified in 30 TAC 334.556-.559. Verification sampling should confirm and demonstrate that compliance with appropriate clean up levels has been attained.

For both Risk Reduction Standards, a final report to the TNRCC documenting compliance with appropriate cleanup levels, including site investigation results, basis for selection of media, contaminants of concern, applicable exposure calculations, description of removal program, and verification data, must be submitted.

2.3 - Field Investigation

2.3.1   Background Constituent Levels

Background concentrations have been established (please see Volume 2) for nine metals in five soils types and the underlying Glen Rose limestone found at CSSA. The nine metals, including arsenic (As), barium (Ba), cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), mercury (Hg), nickel (Ni), and zinc (Zn), were chosen based on known waste disposal records and process knowledge.

Records indicate the potential presence of lead at many other sites including B-31, B-32, and B-33. Sand and projectiles from the building 90 test range were reported to be used as pipe bedding in each of those three SWMUs. Lead may be found at many artillery burn and disposal areas due to spent bullets and its use in high explosives such as lead azide and lead styphnate. Mercury and arsenic, analyzed in a preliminary study and remedial investigation of the B-20 SWMU, were identified at high levels in surface and subsurface soils, exceeding background in several samples (Parsons ES, 1995d). In the same study, barium was detected in all surface and subsurface samples but did not exceed background. Background levels established in previous investigations are shown in Table 2.2.

2.3.2   Field Efforts

All RL17 field activities will be separated into a first field event and a second field event. In general, the activities in field effort 2 hinge on the results of field effort 1. Results from the first field effort indicate whether contamination is present, require decisions about the course of action to take, and dictate the activities during the second field effort. For example, if surface contamination or a subsurface anomaly is discovered during the first field effort, soil borings will be required during the second field effort to identify the extent of contamination. Otherwise, soil borings will not be necessary. The first field effort will be completed for all SWMUs before the second field effort takes place at any SWMU. The tasks to be completed during each field effort are different for each SWMU and are explained in detail in each site’s tabbed subsection, which follow this work plan.

The expected activities to be performed during the first field action are summarized in Table 2.3, Table 2.4, Table 2.5. These tables provide a brief summary of known data and data gathering activities that are expected during the field efforts, including the number of soil samples to be gathered and the analyses to be requested.

In addition, field activities may identify additional SWMUs. All additional SWMUs will be identified and pertinent documentation presented to CSSA and AFCEE.

During both field activities, personnel should be aware of unexploded ordnance (UXO). Many of the sites have been used for the disposal of weapons, fired brass, artillery shells, gunpowder, incendiary materials, etc. All of the disposed munitions should have been discharged prior to disposal. However, if any UXO is encountered, STOP WORK in this area, evacuate the site, and inform the site Health and Safety Officer, Project Manager, the AFCEE Quality Assurance Evaluator (QAE), and the CSSA Environmental Officer of the findings. Stake around the perimeter of the unit. No unauthorized personnel will be allowed in such an area. At this time, all appropriate plans will be amended as necessary.

2.3.3   Locating Solid Waste Management Units

While CSSA records indicate the type of disposal activity at most listed SWMUs, some of the SWMUs could not be located during previous field investigations. As a result, the disposal activity could not be confirmed. Therefore, each SWMU must be physically located during the first field effort. Sites can be located using any of the five listed methods:

If the site cannot be located by one of the first four listed methods, a geophysical survey will be conducted over the suspected area of the site. The geophysical survey will confirm the existence of subsurface anomalies. If the site cannot be definitively located and no anomalies are identified during the geophysical survey, the SWMU will be delisted. This site may have been inaccurately identified in an aerial photograph or identified in CSSA records that reflected the intent to dispose of waste and not the actual disposal of waste at the site.

2.3.4    Geophysical Investigation

Geophysical surveys use either an electromagnetic induction (EMI) detector or ground penetrating radar (GPR) to detect subsurface anomalies over a 20 to 100-foot grid depending on the extent of the site. Subsurface anomalies can indicate landfills, trenches, buried material, and any other soil disturbance or disposal. An EMI survey should be adequate for the needs of this project; GPR will not be used. If the site has not been located, the survey will be conducted over the entire possible extent of the SWMU. The results of a geophysical survey must be calculated and are not immediately known. Therefore, any activities which rely on the results of the geophysical survey must be conducted during the second field effort. Geophysical survey procedures are detailed in the FSP.

2.3.5   Field Sampling

Surface soil samples will be taken from each appropriate SWMU. Whenever surface or subsurface sampling is required, methods and details identified in the associated project FSP sections will be followed. Detailed instructions concerning sampling techniques, holding times, samples sizes, etc., are described in the FSP for all sampled media. Surface soil sampling will be conducted during the first field effort at each site which is scheduled for investigation. If surface constituents exceed background concentrations or a subsurface anomaly is discovered through a geophysical survey, a second field effort involving subsurface sampling will be required to characterize subsurface constituent. Shallow borings will be located where surface samples were taken during the first field effort. Soil/rock samples will be taken from the middle and total depth in each boring.

If water is detected in a boring, a sample will be collected at the unsaturated-saturated interface and analyzed in accordance with potential waste constituents specific to that site. Should no contamination be detected in this sample, the boring will be abandoned in accordance with the FSP. Should contamination be detected, groundwater monitor wells will be installed in accordance with the FSP and groundwater samples will be collected for specific chemical analysis in accordance with guidelines and methods detailed in the FSP and the QAPP.

2.3.6   Sampling and Analysis Plan

The SAP for this work effort includes a QAPP and an FSP for the CSSA SWMU closures.

The QAPP defines the responsibilities and procedures to assure that data is scientifically valid, defensible, and of known precision and accuracy. The following documents will be followed to accomplish these goals:

EPA, RCRA Ground Water Monitoring Technical Enforcement Guidance Document (TEGD), September 1986.

EPA, Data Quality Objectives for Remedial Response Activities, EPA/540/G-87/003, March 1987.

EPA, A Compendium of Superfund Field Operations Methods, EPA/540/P-87/001, December 1987.

HQ AFCEE, Quality Assurance Project Plan, Version 1.1, February 1996.

The FSP sets forth guidance for field work by defining the sampling and data gathering procedures to be used during the SWMU investigation. These field procedures were developed to incorporate standard procedures, such as those of the American Society for Testing and Materials (ASTM), the EPA guidance document entitled "A Compendium of Superfund Field Operations Methods," and applicable Parsons ES operating procedures.

2.3.7   Soil/Rock Borings

For those SWMUs already mapped and geophysical surveys completed, the approximate location of the required samples have been identified and included in this report. If an anomaly was detected or if surface constituents exceed background, borings will be drilled at the identified sampling location. Before any subsurface work proceeds, CSSA and AFCEE will be requested to confirm boring locations.

Total boring depth will be at least 5 feet deeper than the deepest extent of known waste management activities, or if there are no apparent wastes at depth and no records indicate subsurface waste management, drilling will extend at least 5 feet into bedrock. Based on a previous investigation, depths are not expected to exceed 30 feet (Parsons ES, 1995b).

All boreholes will be logged by a qualified geologist during the drilling activity. A qualified geologist is a person who possesses the level of experience and education to provide the specified work in conformance with Parsons ES and technical society requirements. Core samples will be collected every 2 feet for classification and described using the Unified Soil Classification System (USCS). Description categories include lithology, color (using Munsell color chart), fossil content, textural features (e.g. bedding, bioturbation), structural features (e.g. fractures, solution cavities), hardness, and moisture content. Refer to the FSP for additional details.

During drilling activities, if gross contamination is encountered, STOP WORK. Refer to the FSP before proceeding.

2.3.8   Groundwater Sampling

In the event that groundwater is encountered in shallow borings and contamination is detected at the unsaturated-saturated interface through laboratory analysis, a minimum of three borings will be completed as groundwater monitor wells within each such investigated SWMU. CSSA and AFCEE concurrence for sampling groundwater will be obtained in the event surface contamination exist, but the unsaturated-saturated interface is not contaminated. All groundwater monitor wells within the SWMUs will be developed in the water-bearing zone. The proper techniques for installation and development of monitoring wells, purging and sampling groundwater, and the specific chemical analyses to be performed are outlined in the FSP.

2.3.9   Data Quality Objectives

The project data quality objective is to collect adequate data of sufficient quality to provide closure certification to the TNRCC. Each soil and rock sample will be analyzed for the constituents which are likely to be found, based on records of waste disposal, field investigations, and surface constituents. Samples will be analyzed for either volatile organic compounds (VOCs), semivolatile organic compounds (SVOCs), metals, and explosives, or a combination of these specified analytes based on process knowledge and CSSA records.

Ammunition burn areas and fired ammunition brass disposal areas will be analyzed for VOCs, metals, and explosives. Dumps, landfills, and miscellaneous disposal sites will be analyzed for VOCs, SVOCs, and metals in surface soil samples, and for those VOCs, SVOCs, and metals detected at the surface in subsequent subsurface soil samples. These analyses will aid in quantifying environmental contamination in most SWMUs.

2.3.10   Soil Gas Survey

Soil gas surveys are used for detecting the lateral extent of VOCs. For the investigation of appropriate SWMUs, samples will be analyzed for TCE, PCE, cis- and trans-DCE, and BTEX. The presence or absence of BTEX should indicate if fuel contamination exists. The other contaminants are of potential concern because they have been detected in Glen Rose aquifer monitoring wells at CSSA.

Soil gas samples may be taken at five high priority SWMUs (building 43, I-1, B-10, B-15/16, B-23 and B-23A) if additional data is required for closure/remediation. These additional soil gas samples will be collected at a grid spacing agreed to by CSSA, AFCEE, and Parsons ES. Probes will be installed at the grid points and driven until the soil-bedrock interface or refusal is met. After adequately purging the probe, a soil gas sample will be taken and prescreened in the field to verify that it is a valid sample. The sample will then be transported to the field gas chromatograph and analyzed within four hours. A full explanation of the procedures for conducting a soil gas survey is presented in the FSP.

2.4 - Solid Waste Management Unit Closure Activities

This section is divided into an overview of SWMUs under investigation, an overview of general field procedures, and the specific field procedures for low, medium, and high priority SWMUs.

2.4.1   Overview of CSSA Solid Waste Management Units

As part of an environmental assessment, Parsons ES reviewed CSSA waste management records to identify documented SWMUs and followed up with field activities to confirm their approximate locations (ES, 1993b). Map 1 is an aerial photograph of CSSA which shows the locations of the potential SWMUs (Map 1 is in a pocket in Appendix A). Map 2 also presents the SWMU locations on a USGS topographical quadrangle (also in Appendix A). For the purpose of performing site-specific investigations appropriate for closure under TNRCC risk reduction rules, the sites were categorized as low, medium, and high priority sites based on past waste management practices and investigations conducted during the environmental assessment (ES, 1993b). Sites which could not be located during field activities, are expected to be delisted, or where a geophysical survey indicated no subsurface anomalies are designated as low priority sites. Medium priority sites include units where surface trash or stressed vegetation was observed or subsurface solid waste is likely to be encountered. Sites where extensive solid or hazardous waste is known or expected are considered high priority sites.

The following is a general discussion of field activities called for in this portion of the work plan.

2.4.2   Low Priority Solid Waste Management Units

The site subsections detail data collection activities to be provided for each identified low priority SWMU at CSSA. For the low priority units, the proposal calls for reviews of CSSA records and all pertinent data about each unit and geophysical surveys and surface soil samples, as appropriate, for closure. All data collection activities will follow appropriate procedures discussed in the QAPP. A summary of information about each low priority SWMU is listed in Table 2.3.

2.4.3   Medium Priority Solid Waste Management Units

The site subsections detail data collection activities to be provided for each identified medium priority SWMU at CSSA. Note that SWMUs B-1 and B-19 were identified as low priority SWMUs with regard to contamination sources for well 16, but are considered to be medium priority SWMUs for the purposes of closure addressed in this work plan. All data collection activities will follow appropriate procedures noted in the FSP. Known information and expected activities for each medium priority SWMU are summarized in Table 2.4.

2.4.4   High Priority Solid Waste Management Units

Actions to be taken at seven high priority SWMUs are summarized in Table 2.5. In addition, all known high priority SWMUs are listed for completeness. Actions for field effort 1 are summarized in Table 2.6.

2.5 - Closure Reports and Certifications

In order to close a SWMU, a final report should be submitted to the executive director demonstrating compliance under the appropriate risk reduction standards. The report shall include, but is not limited to, the following documentation:

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