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[SWMU B-23]

RL83 Work Plan Addendum, SWMU B-23

May 2000

Soils: Tarrant Association (gently undulating).

Known: Trench identified in the 1966 aerial photograph. Approximately 0.10 acres in size, SWMU B-23 is located approximately 360 feet in the north pasture, northwest of SWMU B-23A, west of RMU-5 and SWMU B-20. in the North Pasture.

Previous Investigations: Under Order 71, SWMU B-23 was observed to consist of a trench, and two green canisters half buried at one end of the trench, and surficial debris in the trench for buried material.

Under Order 67, a geophysical survey was conducted in March 1995. Two anomalies were detected that are potentially associated with past waste management activities.

Under RL17, a work plan for SWMU B-23 was submitted to TNRCC in February 1996. In August 1996, a soil gas survey was performed. No VOCs were detected.

Data Needs: Phase I RFI is needed. Analytical data (VOCs, SVOCs, explosives, and metals) for surface and subsurface soils.

Rationale for Analytical Program: Based on prior identification of the site as a trench filled with soil and two green canisters, 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 additional investigation at SWMU B-23:

  1. Complete three soil borings to characterize the surface and subsurface soils surrounding the area. Approximate locations of the 3 borings are shown on Figure B23-1. Three soil samples will be collected from each boring; one at the surface (6 inches below ground surface), one at a depth of approximately 10 feet, and one at the total depth. The total depth of each boring will be approximately 20 feet or 2 feet below the estimated depth of the waste management unit. Each sample will be analyzed for VOCs, SVOCs, explosives, and metals. QA/QC samples will be collected as described in Section 2.4 of the FSP.

  2. Water is not expected to be encountered in the borings at the site. However, if water is discovered in any of the soil borings, up to one well per area of interest will be completed as groundwater monitoring wells as detailed in Section 2.4.1 of the Work Plan Overview. Groundwater will be sampled, where present, and each sample will be analyzed for VOCs, SVOCs, explosives, and metals QA/QC samples will be collected as described in Section 2.4 of the FSP.

  3. The locations of the soil borings will be recorded using a GPS unit.

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

  5. If the results of the above work indicate that the site can be closed under RRS1 without any further remediation, a technical/closure report will be prepared in accordance with TNRCC closure requirements.