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AOC 65 AETC Work Plan Addendum

Soils: The vat is contained in Building 90, which rests on Tarrant Association (rolling) soils.

Known: The concrete-lined vault is large enough to house a 500 to 750 gallon vat. The metal vat was installed prior to 1966, and removed in 1995. The vat was used for the storage of TCE in Building 90. The concrete vault has been welded shut with a metal plate. In 1995, the use of TCE was replaced with a citrus-based cleaner, which currently is stored in a container that rests on top of the metal plate.

Previous Investigations: None.

Data Needs: Map and analytical data (VOCs and metals) for soils beneath the concrete-lined vault.

Rationale for Analytical Program: Based on prior usage of the TCE storage vat and the remaining concrete vault at the site, chemicals of potential concern include VOCs and metals. Metals (arsenic, barium, cadmium, chromium, copper, lead, mercury, nickel, and zinc) are included due to the metallic vat. VOCs analysis is included in the analytical program to detect any remaining TCE. SVOCs and explosives are not included at this site since no evidence of waste burning or ammunition has been found.

Closure Activities: The following activities constitute an initial investigation of AOC 65. This work will be completed as part of the requirements under the RCRA 3008(h) Order under AETC delivery order 5068.

  1. Field map AOC 65 as described in Section 2.4.1 of the Work Plan Overview.
  2. Remove the metal plate that is currently over the concrete-lined vault. Find the lowest spot in the floor of the vault and an area that appears to have staining. Core through the concrete floor at these two points to soil/foundation materials.
  3. Collect two grab soil samples from the cored area. Each sample will be analyzed for VOCs and metals. QA/QC samples will be collected as described in Section 2.4 of the FSP.
  4. 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 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.