Site Description and History

SWMU B-34 is adjacent to Building 28, where diesel locomotive maintenance was historically performed. CSSA conducted maintenance on locomotives from inside the building. A pit located inside Building 28 was used for CSSA personnel to perform maintenance activities on locomotive and railway equipment. SWMU B-34 consists of the below-grade piping and pipe bedding that drained from the pit. The piping extends 230 ft southwest from Building 28, travels underneath an open field, and drains to an outfall area near McElroy Road. SWMU B-34 covers an area of approximately 0.5 acres. The outfall area drains to a ditch adjacent to the northern side of McElroy Road. This ditch drains from east to west along McElroy Road, then travels south through a culvert constructed beneath McElroy Road. Figure B34-2 is an aerial photograph from 2003, showing the location of SWMU B-34.

Summary of Previous Investigation Results

Geophysical Survey

In March 1996, an EM geophysical survey was performed at SWMU B-34. One anomaly caused by Building 28 was discovered, but no anomalies related to waste management activities were found.

Surface Soil Samples and Soil Borings

Three soil borings were advanced at SWMU B-34 during March 2000. Surface samples were collected adjacent to borings RW-B34-SB02 and RW-B34-SB01. The three borings were advanced near or directly above the pipeline. An additional soil sample (RW-SB34-SS03) was collected near the end of the sewer line. In March 2003, fourteen additional surface soil samples were collected in an effort to delineate the horizontal extent of metals contamination.

Analytical data from all surface samples reported metals concentrations exceeding the applicable RRS1 closure criteria. Of specific concern are the concentrations reported for chromium, copper, zinc, and lead. In addition, metals concentrations exceeded RRS1 closure standards for all subsurface rock samples in all three borings.

The March 2003 surface soil analytical data shows all of the metals except arsenic, barium, nickel, and cadmium exceeded their RRS1 criteria. Chromium, copper, zinc, and lead exceeded their background standards four or more times, with lead exhibiting the highest reported values. The horizontal extent of surface soil contamination has not yet been determined at the site.

Sampling Recommendations

Closure of SWMU B-34 under RRS1 requires identification of the horizontal extent of contamination and removal of contaminated soil at the site. The waste must be removed from CSSA for off-post disposal to pursue RRS1 closure with respect to the soil unit at SWMU B-34. Groundwater and competent bedrock will be addressed as part of the groundwater operable unit. The soil excavation will extend to the depth that waste or waste residue is encountered or to bedrock, whichever comes first.

Since the horizontal extent of contamination has not yet been defined, additional surface soil sampling is recommended. Additional surface soil samples will be analyzed for chromium, copper, and zinc (SW-6010B); and lead (SW-7421). The use of field immunoassay kits will be considered due to the expeditious turnaround time for the results. Once the extent of contamination is better quantified, a closure plan will be developed.

Summary Of Planned Work

1. Collect additional surface soil samples for barium, cadmium, chromium, copper, lead, nickel, and zinc analyses to delineate the horizontal extent of contamination.

2. Evaluate extent of contamination to determine if excavation and off-site disposal is possible with the current project budget. If so, excavate contaminated soils.

3. Collect samples of excavated soils for waste characterization purposes. One composite sample consisting of five aliquots will be collected per 1,000 CY of soil. Analyze samples for TPH and TCLP antimony, arsenic, barium, beryllium, cadmium, chromium, lead, mercury, nickel, selenium, and silver. Stabilize waste with PIMS material, if necessary, prior to disposal.

4. Collect samples of the excavation sidewalls and bottom. Samples will be collected at a frequency of one per 100 linear ft of sidewall, and one per 20,000 ft² of bottom surface area. Samples will be analyzed for barium, cadmium, chromium, copper, lead, nickel, and zinc.

5. Continue excavation until RRS1 soil criteria or competent bedrock, whichever comes first, is reached.

6. Re-grade the site with clean fill and reseed.

7. Validate data and prepare Closure Report for SWMU B-34.