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[SWMU B-31]

Soils: Krum Complex

Known: Sand and projectiles from the Building 90 test firing room were used as pipe bedding at solid waste management unit B-31 (ES, 1993b). Only the pipe and bedding constitute the unit.

Previous Investigations: SWMU located during field activities.

Data Needs: Map, geophysical survey, and analytical data of surface soils.

Closure Activities: The field team should be observant for UXO. The following field activities will be performed to gather data for TNRCC closure submittal of SWMU B-31.

SWMU B-31 Field Effort 1

1. Review historical records as described in Section 2.4.1 of the Work Plan Overview.

2. Field map the SWMU as described in Section 2.4.1 of the Work Plan Overview.

3. Conduct a geophysical survey of the SWMU as described in Section 2.4.1 of the Work Plan Overview.

4. Identify the location of the pipe. Sample and analyze surface soils from three locations in the pipe bedding near the middle section and halfway towards each end of the pipe as described in Section 2.4.1 of the Work Plan Overview. Analyze each sample for explosives and metals (as outlined in the FSP).

SWMU B-31 Field Effort 2

1. Three soil borings will be drilled to characterize the subsurface soils.

a) Locate, receive approval, and drill three soil borings to monitor potential leachate from the pipe bedding as described in Section 2.4.1 of the Work Plan Overview.

b) Obtain two samples per boring near the middle and total depths as described in Section 2.4.1 of the Work Plan Overview.

c) Analyze each subsurface sample for explosives and metals identified in the surface soils (as outlined in the FSP).

2. 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 monitor wells as detailed in Section 2.4.1 of the Work Plan Overview. Sample groundwater, where present, and analyze each sample for explosives and metals identified in the surface (as outlined in the FSP).

3. Handle the IDW in accordance with the FSP.

 

Known (Updated): Approximately 650 feet of active sanitary sewer pipe (8-inch PVC) east of Building 92 (Figure B31-1) were thought to have been bedded in lead-contaminated sand containing shot which was generated at the Building 90 test firing room. It is estimated that the bedding extends to a depth of approximately 3 feet and is approximately 2 feet wide. The B-31 unit consists of the bedding material only.

Excavation was conducted at the site with the intention of removing all of the shot and associated contaminated soils from the ground. Seven test pits were dug to determine where along the line the lead-contaminated sand and shot were believed to be located. These test pits (T1 through T7) were each approximately 6 feet deep, 10 feet long and 5 feet across. The pits are approximately 100 feet apart. No lead-contaminated sand or shot was encountered.

Previous Investigations (Updated): Surface soil and subsurface soil samples were collected at B-31 in 1996 and 1997 at locations shown in Figure B31-1. However, these data are in question due to ITS’ questionable laboratory practices.

Data Needs: As described above, the extent of pipe bedding consisting of shot with lead material, if any, needed to be determined. In July 1997, it was found that no shot with lead material was used along this portion of the sewage line.

Closure Activities: Excavations were made to determine the extent of pipe bedding made up of shot and lead-contaminated sand; none was found. Confirmation sampling was recently conducted also. The activities that were conducted are as follows:

CSSA personnel diverted the sanitary line to allow excavation underneath the pipe.

A total of seven test pits were dug along the line to identify which portion of the line had shot and lead-contaminated sand bedding. No shot with lead-contaminated sand was identified.

A LeadCheck® field test kit was used to determine if elevated lead levels occur in the underlying soil. This test kit was used solely as a field aid for determining if any of the potentially contaminated material existed. Analytical samples for laboratory analysis were collected as described in item 5 below.

Since the line is active, the trench was filled back in quickly to prevent pipe damage. CSSA personnel will backfill the trench with clean fill.

To verify that no shot and lead-contaminated soils had been used, confirmation soil samples were collected at a rate of one per test pit. Each test pit measures approximately 10 feet long by 5 feet across by 6 feet deep, and they are approximately 100 feet apart. These samples were analyzed for copper, lead, and zinc using methods listed in the table below. These metals were the contaminants identified during the previous phase of work as exceeding background levels. Results are pending.