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[SWMU B-1]

Solid Waste Management Unit B-1

RL17 Work Plan Amendment for Data Quality Rework, May 2000

Known: No geophysical anomalies associated with waste management practices were observed during geophysical survey activities on 10 February 1995.

Previous Investigations: Soil borings have been drilled at six locations during the course of two field efforts. Three soil borings were completed and nine soil samples were collected (three samples each boring) on 21 and 22 February 1995. Each sample was analyzed for VOCs, SVOCs and metals by Chemron, Inc. of San Antonio, Texas. Three phthalate isomers were reported in all borings. Due to a laboratory error, one replacement boring was re-drilled next to SB1 to collect additional VOC samples on 13 June 1995. This additional boring was labeled SB1R. No VOCs were detected by Chemron during the re-sampling effort. Results for borings SB1 through SB3 are provided in Table B1-1.

A sample of shallow perched groundwater was collected from SB3 on 23 February 1995 and analyzed by Chemron for SVOCs, VOCs and metals. A detectable concentration of chromium was reported in the SB3 borehole groundwater; however, this concentration (0.01 mg/L) was well below the RRS2-GW standard (0.1 mg/L), as shown in Table B1-2.

An additional three borings (SB4, SB5, and SB6) were completed between 20 August 1996 and 5 September 1996. These boreholes were drilled adjacent to SB1, SB2, and SB3 to verify the SVOC results reported in 1995. These subsurface soil samples were analyzed by ITS Laboratory for bis(2-ethylhexyl)phthalate, butylbenzylphthalate, and di-n-butylphthalate based on 1995 investigative results. No groundwater was encountered during this investigation.

Planned Rework: Replace previous analytical chemistry data generated by ITS Laboratory. To accomplish this, complete three additional soil borings in the approximate locations of SB4, SB5, and SB6. These borings will be named RW-B1-SB4, RW-B1-SB5, and RW-B1-SB6. Obtain two subsurface soil samples from RW-B1-SB5, and three subsurface samples from RW-B1-SB4, and RW-B1-SB6. Analyze samples for bis(2-ethylhexyl)phthalate, butylbenzylphthalate, and di-n-butylphthalate only.

Rationale for Analytical Program: Based on previous analytical results, chemicals of potential concern include phthalates only. Phthalates were the only contaminants detected above background levels during previous investigations. Therefore, the analytical program for this effort includes phthalates only.

Resampling Activities: The following field activities will be performed to gather data for TNRCC closure submittal of SWMU B-1:

1. The boring logs from the original drilling of SB4, SB5, and SB6 will be copied and reviewed by the supervising geologist prior to beginning any rework at SWMU B-1. In particular, the geologist will review the PID readings and recovery volumes obtained from the existing boring.

2. Field locate previous sample locations (collected in 1996).

3. Complete three soil borings in the approximate locations of the SB4, SB5, and SB6 and 1996, as shown in Figure B1-1. The rework soil samples will be collected at each boring from the same depth intervals as the first set of subsurface soil samples, unless field instruments indicate that VOCs are present in the boring from a different depth. If PID readings indicate VOCs are present, then the subsurface soil sample from that interval will be submitted to the laboratory for analysis. The total depth of each boring will be at approximately the same depth as the first set of soil borings (SB4 = 27 feet, SB5 = 22.5 feet, and SB6 = 38 feet BGL). Each rework sample will be analyzed for bis(2-ethylhexyl)phthalate, butylbenzylphthalate, and di-n-butylphthalate, as indicated in the following table. QA/QC samples will be collected as described in Section 2.4 of the FSP (see Volume 1-4).

4. Boring logs for the rework soil borings will not be completed. Instead, the original boring logs created from the boring completed in 1995 or 1996 will be available onsite during rework activities. Changes to the boring logs will be made if field personnel observe a difference in the rework boring from the original soil boring.

5. Water is not expected to be encountered in the borings at the site. If water is discovered in any of the soil borings, it will be reported to AFCEE and CSSA immediately. Completion of wells is beyond the scope of this rework as no monitoring wells were previously installed at the site.

6. Handle IDW as specified in the FSP.

7. Analytical results for the data quality rework samples will be reported in the Rework ITIR.

8. If the results of the above work indicate that the site can be closed under RRS1 without any further investigation and/or remediation, a technical/closure report will be prepared under the RL17 SOW and submitted in accordance with TNRCC closure requirements. If the site does not meet RRS1 closure requirements, a technical report describing the results of the investigation and recommended additional investigation and/or remediatoin will be prepared under the RL17 SOW.

Historical Analytical Program and Rework Sampling Plan

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