AOC 41 - AETC Work Plan Addendum

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Area of Concern 41

AETC Work Plan Addendum

Soils: Krum Complex.

Known: The site is located in the gate area east of Well 16 in the North Pasture (north and west of Gate 6), and is approximately 5.9 acres in size.

Previous Investigations (Updated): Under Order 67, a geophysical survey was conducted in May 1995 at all "open" areas within a 2,000-foot radius of Well 16. Three anomalies were found, and are included as AOC 41. Anomaly A is subtle and is not related to known surface/subsurface features. Anomaly B is the largest and may be related to additional underground metal piping or fragments. Anomaly C is associated with a burn pit at the site.

In June and July 1995, twelve soil gas survey samples were collected and analyzed for chlorinated and aromatic volatile organics. PCE was detected in this area (0.07 ug/L was the highest concentration detected).

Data Needs: Analytical data (VOCs and metals) for subsurface soils and a soil gas survey.

Rationale for Analytical Program: Based on the site’s vicinity to well 16 and prior investigations 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 possibility of burned metal in Anomaly B. VOCs analysis is included in the analytical program based on soil gas survey results. SVOCs and explosives are not included at this based on the soil gas and geophysical survey results.

Closure Activities: The following activities constitute an additional investigation of AOC 41. Some of this work will be completed as part of the requirements under the RCRA 3008(h) Order under AETC delivery order 5068.

	Conduct a soil gas survey of the mapped site in order to complete contour lines above Well 16. The soil gas survey will be set on a 100 ft. grid and tied into soil gas information collected from AOC 37 and AOC 66. Up to 40 points will sampled as shown on Figure AOC41-1.
	Complete three soil borings to characterize the subsurface soils surrounding the area. One boring will be completed in anomaly A, one boring will be completed in anomaly B and one boring will be completed in anomaly C. Three soil samples will be collected from each boring; one at the surface, one at the middle of the boring and one at the total depth. The total depth of each boring will be approximately 10 feet or until 2 feet is drilled into the bedrock. Each sample will be analyzed for VOCs and metals. QA/QC samples will be collected as described in Section 2.4 of the FSP. Currently, this task is not included in AETC DO5068.
	Handle IDW as specified in the FSP.
	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.