SWMU B-32 RCRA Facility Investigation/Closure Report

Section 3 - Conclusions and Recommendations

3.1 - Conclusions

SWMU B-32 contained lead-shot-contaminated sand used as backfill for a PVC sanitary sewer pipeline. The sand fill was reportedly contaminated with lead and contained shot material. The geophysical survey revealed no geophysical anomalies related to past waste disposal activities. Lead-shot contaminated sand was reported in test pit excavations. Approximately 36 cubic yards of visibly-affected material was excavated from the pipe trench, treated, and disposed offsite in a permitted municipal waste facility.

Three soil borings were drilled adjacent to the pipeline trench following removal of the contaminated sand. Although concentrations of barium, cadmium, chromium, nickel, and zinc exceeded RRS1 criteria for the Glen Rose Limestone, most of the exceedances were below Texas-specific median background concentrations. All results were below background levels for CSSA soils. Soil boring logs indicate that interbedded clay layers were encountered in limestone in borings SB01 and SB03, and fill material was encountered to a depth of 7.5 feet in SB02. This clay and fill material likely has background concentrations more comparable to CSSA soils concentrations rather than the Glen Rose Limestone.

3.2 - Evaluation of Data Quality Objectives Attainment

Overall 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-32, 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-32 investigation are to determine if the site meets TCEQ requirements for RRS1 closure and requirements of the 3008(h) Administrative Consent Order.

All data generated during the SWMU B-32 investigation were reviewed to confirm conformance with the AFCEE QAPP; the data verification report is included in Appendix D. All data are considered usable for site characterization purposes. Although several results are flagged with a “J,” these results are considered usable because the estimation of quantitation does not significantly affect the sample results. All initial calibration, second source verification, and internal standard criteria were within quality control limits, as described in the data verification report (Appendix D).

3.3 - Recommendations

All waste has been removed from the site. Although metals concentrations slightly exceed background levels for Glen Rose Limestone, most of the concentrations are below the Texas-specific median background levels. The only exceptions are zinc, which was detected in three samples at concentrations ranging from 32.2 mg/kg to 59.4 mg/kg (Texas-specific median is 30 mg/kg), and nickel, which was detected in two samples at concentrations ranging from 17.0 mg/kg to 23.6 mg/kg (Texas-specific median is 10 mg/kg). Furthermore, all metals concentrations detected were below the CSSA soils background concentrations. Because the waste has been removed and all remaining metals levels for soil samples collected from the site are below the background concentrations for CSSA soils, closure under RRS1 is recommended.

3.4 - Certification

Partial Facility Closure Certification

Solid Waste Management Unit B-32

Department of the Army

Camp Stanley Storage Activity

Boerne, Texas

I certify that the above-described closure was performed under my direction, in accordance with the work plan and 30 TAC §335 Subpart S, and as described in this report, and that, to the best of my knowledge and belief, said closure has been successfully accomplished.