3.1 - Conclusions

SWMU B-34 consists of the below-grade piping that drained from the pit area inside Building 28. The pit was used by CSSA personnel to perform maintenance activities on locomotive and railway equipment. The drain has been closed and sealed. The drain from the outfall flows southwest to McElroy Road and south toward AOC 57. Potential COCs associated with SWMU B-34 include VOCs, SVOCs, and metals. Investigation activities conducted at SWMU B-34 included the performance of a geophysical survey, surface soil sampling, and subsurface soil/rock sampling. The geophysical survey did not indicate any anomalies other than those associated with the building. However, analytical results show that SWMU B-34 does not meet RRS1 standards with respect to all COCs.

Analytical data gathered from March 2000 reported concentrations above the applicable RRS1 criteria for various metals and bis(2-ethylhexyl)phthalate. Bis(2-ethylhexyl)phthalate was detected above the RRS1 criteria in subsurface samples from all three borings performed. However, in the absence of any other exceeding VOCs or SVOCs, bis(2-ethylhexyl)phthalate concentrations detected in exceedance of the RL are considered to be associated with laboratory or sampling equipment bias, specifically the gloves worn during sample collection. No other VOCs or SVOCs were reported above laboratory RLs.

Analytical data from all surface samples and all three soil borings reported metals concentrations exceeding the applicable RRS1 criteria (background values). Of specific concern are the concentrations reported for chromium, copper, zinc, and lead. Chromium concentrations reported ranged from 8.2 mg/kg to 96.0 mg/kg. Four of these samples exceeded the Texas-Specific Background Concentrations for chromium of 30 mg/kg. Copper was reported at concentrations ranging from 26.3 mg/kg to 135.8 mg/kg, and all five samples exceeded the Texas-Specific Background Concentration for copper of 15 mg/kg. Zinc was reported at concentrations ranging from 20.2 mg/kg to 204.2 mg/kg. Five sample results exceeded the Texas-Specific Background Concentration for zinc (30 mg/kg). Lead results ranged from 14.95 mg/kg to 611.20 mg/kg in four samples. Three of these samples exceed the Texas-Specific Background Concentration for lead of 15 mg/kg. A majority of sampling results exceed RRS1 criteria (background values) as well as Texas-Specific Background Concentrations.

3.2 - Evaluation of Data Quality Objectives Attainment

Overall data quality objectives (DQOs) for the investigations at CSSA are provided in Volume 1-1 behind the RFI Addendum tab (Section 11 of the Work Plan Overview). A detailed list of DQOs for SWMU B-34, along with an evaluation of whether each DQO has been attained, is provided in Appendix C. As described in Section 1, the main objectives of the SWMU B-34 investigation are to determine if the site meets TNRCC requirements for RRS1 closure and to meet requirements of the 3008(h) Administrative Consent Order.

All data generated during the SWMU B-34 investigation were reviewed to confirm conformance with the AFCEE QAPP; the data verification reports are included in Appendix D. All data are considered usable for site characterization purposes. Although several results are flagged with an “M”, these results are considered usable because the matrix interference is minimal and does not significantly affect the sample results. In addition, several results are flagged with a “J”. These “J” flagged results are considered usable because estimation of the quantitation does not significantly affect the sample results. All of the initial calibration, second source verification and internal standard criteria were within quality control limits, as described in the data verification report (Appendix D).

The site does not meet the TNRCC RRS1 requirement for removal of all waste. Several of the 3008(h) RFI requirements, such as identification of waste characteristics and determination of extent of contamination, have also not yet been met.

3.3 - Recommendations

Analytical data collected from SWMU B-34 reports concentrations of metals that exceed RRS1 standards (background values) and Texas-Specific Background Concentrations. Since the extent of contamination has not been determined, additional sampling is recommended. In the vicinity of SB01, SB02, and SB03, it is estimated that approximately 15 additional samples are needed to identify the extent of contamination. These samples should be analyzed for barium, chromium, copper, nickel, and zinc (SW-6010B); cadmium (SW-7131A); and lead (SW-7421). In addition, collection of three additional samples at the outfall of the pipe (in the vicinity of SS03) for VOCs (SW-8260B), SVOCs (SW-8270C), and metals (listed above) analysis is recommended to ensure that any discharges from the pipe to the ground surface are identified.

The results of these additional analyses should be used to determine the extent of soils requiring remediation or disposal. Excavation of surface soils from the location of RW-B34-SB01 to RW-B34-SB03 should be conducted to a depth of 4 feet. The estimated volume of surface soils to be disposed is 135 cubic yards. An additional excavation should be conducted at the location of RW-B34-SS03 to a depth of one foot below ground surface. Evaluation of the results of additional sampling proposed above will clarify the amount of excavation necessary.