Investigations at several low, medium, and high priority SWMUs at CSSA were conducted as described in Sections 1 through 7 of this work plan. The majority of samples collected as part of this work under RL17 were analyzed by ITS Laboratories (ITS) in Richardson, Texas. Fraudulent work from ITS was disclosed in January 1998, and the lab continues to be reviewed by EPA. In a letter dated April 26, 1999, EPA determined that any original ITS analyses for any method, and any reprocessed data, do not comply with EPA quality requirements. EPA concluded that ITS data might be used for evaluation and screening, but ITS data would not be acceptable for clean up or compliance purposes.

This addendum (Section 10) is added to the work plan, and consists of a plan for resampling to replace analytical chemistry data originally provided by ITS that was to be used for site closures at CSSA. Samples collected from 25 Solid Waste Management Units (SWMUs) were analyzed by ITS under subcontracts associated with AMC Delivery Orders RL17 and RL33, and Armstrong Lab Delivery Order 126. Where data were not to be used for site closures, limited or no rework is planned. In some cases, the conditions at the site have changed significantly since the original samples were collected, and the data cannot be replaced. An example of this is the O-1 oxidation pond, where a pilot-scale electrokinetics treatability study was conducted between July and December 1997. The soil chemistry of the test area was affected by acidification, a process deemed necessary by the bench scale test to improve metals movement during electrokinetics. Soil data from before the treatability study cannot be replaced, and therefore, ITS data are considered to be screening data for the site. New work is currently scoped and underway for several sites, including B-24 (work scoped under RL33), B-28 (work scoped under RL83), Demo Dud area (work scoped under RL83), O-1 (work scoped under RL83), and groundwater monitoring (work scoped under AFCEE DO23, RL74, and RL83); therefore, no rework is proposed for these sites. This addendum discusses all 25 SWMUs and groundwater, and proposes to collect rework samples to replace the ITS-generated analyses for 21 SWMUs. Site-specific rationale for the resampling plan is provided behind in the site-specific links in Volume 1-2.

The work proposed at the affected sites will be conducted in the same manner as the original work, with some exceptions. For instance, since soil borings were logged during the initial effort, and rework soil borings will be drilled adjacent to the former locations, new drilling logs will not be prepared. However, significant differences between the original boring logs and observations during the rework drilling will be noted on the original boring logs. The same methodologies and project controls established during previous work (Sections 1 through 4) are still valid for this addendum.

This plan describes investigations and closure activities, or rationale to not collect samples, for the 25 SWMUs listed in the following table. Groundwater rework is also addressed in the rework planning. The locations of the SWMUs under discussion are shown in Figure 10.1. A brief description of each site is also provided in Table 10.1 below.

This document was prepared by Parsons Engineering Science (Parsons ES) for CSSA. This Section 10 is an addendum to the RL17 work plan (Section 1, Section 2, Section 3, and Section 4). It describes the scope of rework at the SWMUs.

10.1 - Description of Rework

The objective of the rework at 21 SWMUs is to collect soil samples as close as possible to the original sampling locations and to analyze the samples in accordance with the original analytical methods. The rework samples will be analyzed and the laboratory reports validated. The results will be reported in the format of an analytical Informal Technical Information Report (ITIR). Upon approval of the rework sampling and analyses and ITIR, the data will be evaluated under the scope of the AMC delivery orders and included in the required closure/investigation report per site.

This addendum describes the following tasks:

10.2 - Rationale and Methodology

The following sections describe the rationale and methodology of the additional field actions at sites.

The field efforts to be conducted at the rework sites addressed in this addendum are summarized in Table 10.2 below.

Table 10.2 - Summary of Field Efforts, Rework Plan Addendum

The procedures for field sampling of surface soil samples will follow those described in Section 2 of the work plan, the FSP (Parsons ES, 1996a) and the AFCEE Master FSP. Media to be sampled are surface and subsurface soils.

The number of samples to be collected at each site is described in the site-by-site descriptions in Volume 1-2 and is summarized in Table 10.2. Sample collection and handling techniques will follow the Sampling Analysis Plan (SAP) for SWMU Closures at CSSA. Analytical techniques will follow procedures described in Test Methods for Evaluating Solid Waste, U.S. Environmental Protection Agency, SW-846 and Version 3.0 of the CSSA QAPP.

Four types of field quality control (QC) samples will be collected during the investigative effort. QC samples to be collected include equipment blanks, field duplicate samples, trip blanks, and matrix spike/matrix spike duplicate (MS/MSD) samples. Sample descriptions, identifications, and frequencies required are described in detail in the SAP.

In addition to surface soil samples which will be collected from the 0-6 inch interval below the ground surface, soil borings will be drilled at 17 sites to the original depths. Two to three samples will be collected from each boring in accordance with previous work. Anticipated sampling depths are at the depth of the detected anomaly and the total depth of the boring. The drilling, sampling, and IDW handling will be conducted in accordance with the FSP. Table 10.3 lists the number of borings, samples, and analytical parameters for each site. The rationale for the analytical program is described in Section 10.2.5.

The evaluation of background metals levels in soils and bedrock at CSSA was initiated in early 1994 when ten samples each of background bedrock and soil were collected in association with closure of one of CSSA’s SWMUs (F-14). These ten samples (SS1-SS10) were analyzed by NET Laboratory for nine metals (arsenic, barium, cadmium, chromium, copper, lead, mercury, nickel, and zinc) and results were used to determine a representative background concentration for bedrock and one for soil for CSSA.

Later in 1994, regulatory agencies required that CSSA individually evaluate each of eight soil types occurring at the facility, as well as the one rock type (Glen Rose Limestone) which outcrops at the facility. At that time, the only ongoing investigation was at the B-20 OB/OD area, where six metals (arsenic, barium, cadmium, chromium, lead, and mercury) levels were being evaluated. Three soil types (Krum Complex, Crawford and Bexar stony soils, and Brackett-Tarrant association) occur at the B-20 site; therefore, additional background soil samples were collected for these three soil types for the six metals of concern. A total of 25 additional samples (SS11-SS35) were necessary to create a set of ten samples for each of the three soil types. These additional samples were analyzed by Terra Laboratory and the results were used to determine representative background levels of arsenic, barium, cadmium, chromium, lead, and mercury in Krum Complex, Crawford and Bexar stony, and Brackett-Tarrant association soils.

Table 10.3 - Summary of Analytical Program, Rework Plan Addendum

When investigations of several other SWMUs were initiated in 1996, additional background sampling was conducted to provide sufficient data for determining background levels of the previously identified five metals (arsenic, barium, cadmium, chromium, lead, and mercury), as well as copper, nickel, and zinc for the Glen Rose Limestone and all eight soil types at CSSA. A minimum of ten samples of each soil type is required for a statistically valid evaluation. The additional sampling included 45 samples (SS36-SS80) analyzed for eight metals, and 25 samples (SS11-SS35) for copper, nickel, and zinc. ITS Laboratory analyzed these samples and results were used to determine representative background concentrations for each of the eight metals in eight soil types and bedrock.

Parsons ES proposes to recollect any samples analyzed by ITS Laboratory, and repeat the statistical evaluation using the replacement analytical results. Background samples will be collected in the same locations as those collected previously (with one exception), and samples will be identified with same ID number; however, all rework samples will be preceded by "RW" to distinguish them as rework samples (i.e., "RW-BKGR-SS11"). The one exception is sample BKGR-SS60; the original location is inside the boundary of AOC 39, so the location will be revised slightly to move it out of the AOC. Table 10.4 lists the background samples which Parsons ES proposes to recollect.

The statistical evaluation will be conducted using the same statistical methods as those used in the June 1997 Evaluation of Background Metals Concentrations in Soil Types, which is included in Volume 2. The June 1997 evaluation, and the methodology used therein, was approved by the TNRCC in September 1997.

Chemicals of potential concern (COPCs) for each site were determined by investigating past waste generating activities at CSSA. A list of COPCs was developed from past waste records as well as process knowledge. In addition, a phased approach has been taken to the investigations. The first phase is an initial screening for contamination through limited sampling, geophysical surveys, and soil gas surveys, where appropriate. The second phase will be to identify the nature and extent of contamination, where detected.

The majority of CSSA’s sites are solid waste disposal areas (trenches). Samples from these sites are analyzed for VOCs and metals. Where UXO is suspected, samples are also analyzed for explosives. Where it is suspected that waste was burned in the trench, samples are also analyzed for SVOCs.

At any site in the screening phase of investigation, analyses include all analytes within the VOC, SVOC, and explosives analytical methods when these tests are done. If any analytes are detected at concentrations above risk-based standards, additional investigations will be conducted to determine the nature and extent.

The list of metal analytes known to have been previously managed at CSSA include arsenic, barium, cadmium, chromium, copper, lead, mercury, nickel, and zinc. These metal analytes are included for all screening investigations. If any of the metals are not identified during the initial phase of investigation, subsequent investigations will not include those specific metals not identified in the previous investigation.

Chemicals of concern (COCs) will be selected after the cumulative potential risk for human health is determined and an ecological risk evaluation is conducted.

10.3 - Reporting

Two reports will be generated as part of the rework effort. The first is the background evaluation report described above in Section 10.2.4. The second is an analytical ITIR described below.

The rework samples will be analyzed and reported by the laboratory. Parsons ES will validate these reports. The validated data will be placed in an analytical ITIR to be prepared in accordance with the AFCEE ITIR format, including cross-referencing of sample delivery packages. The ITIR will be submitted to AFCEE, CSSA, and AMC for review, as well as to regulatory agencies if requested. Upon approval of the ITIR, the rework will be complete. The validated rework data will then be evaluated in conjunction with other site data and placed in investigation/closure reports per site, under the scopes of work per AMC delivery orders RL17 and RL33.

Table 10.4. - Summary of Rework Background Surface Soil Samples, Rework Addendum

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