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SWMU Demo Dud Area (DD) Area

RL33 RFI Work Plan, March 1997

Soils: Brackett and Tarrant Association, rolling

Known: The demolition dud area consists of approximately 3.5 acres in the inner cantonment area of CSSA. Prior uses of the site are unknown; however, the area was posted with "Demolition Dud Area" warning signs. Investigation of the site commenced with a sweep for surface UXO. During this work, a disposal trench measuring 250 feet long and estimated to be about 2 feet deep was identified. A map of the site is included as Figure DD-1. A number of UXO items have been identified, primarily including fuses and Stokes mortars. The trench consists of waste scrap metal and UXO mixed in a soil matrix.

Previous Investigations: UXO identification work has been completed at the demolition dud area. During this work, the disposal trench was identified. A number of UXO items were identified, including primarily fuses and Stokes mortars.

Data Needs: Verification that no UXO is present in the trench was needed. Analytical data to verify that soil matrix in and below trench meets RRS1 criteria is necessary.

Closure Activities: The following field activities will be performed to gather data for TNRCC closure submittal of the demolition dud area.

1. The trench consists of waste scrap metal and possibly UXO mixed in a soil matrix. This material was excavated and sifted to remove the UXO and metal scrap.

2. The sifted soil will be sampled to ensure that it meets background (RRS1) criteria. Samples will be collected at a rate of one per 500 yd³ and analyzed for the compounds listed in the following table. Each sampled lot of 500 yd³ will be delineated in the field in case analytical results indicate that the soil does in fact exceed background. If a lot does exceed background, three additional samples will be collected from that lot, and analyzed for the exceeding contaminant, to identify the portion of the lot exceeding background.

3. If sifted soil samples indicate contamination, three soil borings will be drilled to characterize the subsurface soils surrounding the trench. Two soil samples will be collected from each boring; one near the middle of the boring and one at the total depth. The total depth of each boring will be a maximum of 10 feet (five feet below the bottom of the waste management unit). Each sample will be analyzed for VOCs, explosives, and metals, as listed in the table above.

4. Water is not expected to be encountered at the site. However, if water is discovered in any of the soil borings, all three borings will be sampled and potentially 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, explosives, and metals identified in the soil samples.

5. IDW will be handled as specified in agreed procedures identified by TNRCC letter dated 12 August 1996.

6. 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 state closure requirements.