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Area of Concern 47

RL83 Work Plan Addendum

Soils: Trinity and Frio soils (frequently flooded).

Known: The site consists of trenches and mounds similar to SWMU B-15/16. The site is located approximately 60 feet south of SWMU-15/16 on the southern boundary of CSSA, in the southwest area of East Pasture, and is approximately 0.3 acres in size.

Previous Investigations: Site was identified during field efforts during the investigation of SWMU B-15/16.

Data Needs: Map, geophysical survey and analytical data (VOCs, SVOCs, explosives, and metals) for surface soils.

Rationale for Analytical Program: Based on the trenches and mound at the site, chemicals of potential concern include VOCs, SVOCs, metals and explosives. Metals (arsenic, barium, cadmium, chromium, copper, lead, mercury, nickel and zinc) are included due to the potential metallic nature of the waste. Ammunition may include explosives residue; therefore, an analysis for explosives will be conducted. VOCs analysis is included in the analytical program to detect typical contaminants associated with a disposal area. SVOCs are included at this site since waste burning may have occurred.

Closure Activities: The following activities constitute an initial investigation of AOC 47:

  1. Field map AOC 47 as described in Section 2.4.1 of the Work Plan Overview.

  2. Remove any vegetation necessary to complete field activities listed below. If any potential UXO is observed, work will cease until UXO specialists are brought on site to identify and remove UXO.

  3. Conduct a geophysical survey of the mapped site, as described in Section 2.4.1 of the Work Plan Overview, to identify any anomalies. A ground penetrating radar (GPR) device and an EM-31 instrument will be used to complete the geophysical survey with approximately 32 survey points on a 10-foot grid. The approximate locations of the survey points are shown on Figure AOC47-1. The locations of four of the corners of the survey points will be recorded using a GPS unit. Analysis of the EM data will follow field activities.

  4. Collect three grab surface soil samples at a depth of six inches below surface grade. The samples will be biased toward any anomalies found during geophysical survey activities. Each sample will be analyzed for VOCs, SVOCs, explosives, and metals. For planning activities, the approximate locations of the surface soil samples are shown on Figure AOC47-1. QA/QC samples will be collected as described in Section 2.4 of the FSP.

  5. IDW will be handled as specified in the FSP.

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