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SWMU B-30 Closure Report
Section 2 - Closure Activities
SWMU B‑30 is a former quarry area that had been used for disposal of construction debris. Based on the RFI sampling results, closure of SWMU B‑30 required excavation and disposal of the waste and waste residue present at the site, excavation/investigation of a subsurface geophysical anomaly, and confirmation sampling to ensure that all waste and waste residue was removed. These closure activities are described in this section.
Excavation of waste and waste residue at SWMU B‑30 was conducted from November 2003 to May 2004. During this period, approximately 1,700 CY of soil and waste material were excavated from the site. Cleanup activities included excavation and removal of all surface and subsurface waste, excavation and removal of contaminated soils in the vicinity of RW-B30-SS03, and excavation and removal of any waste encountered in the area containing Anomaly B. Waste material that was recovered included construction debris, ammunition debris, and one rusted drum. The drum contained some spent 50 caliber casings, which is not considered ordnance. The drum contained no liquid, no visible markings were present on the drum, and no odor was detected. All excavation activities were conducted by Eagle Construction and Environmental Services of San Antonio, Texas, under the supervision of a Parsons Construction Manager.
The excavated area measured approximately 225 feet (east-west) by 50-75 feet (north-south). The topography is variable at SWMU B-30; therefore, the excavation depth varied across the site. In general, the excavation on the west side of the site was very shallow and increased to the north and east. Excavation depths ranged from one to ten feet. Figure B30‑9 shows the approximate area of excavation at SWMU B‑30.
Excavated material was stockpiled onsite for waste characterization. Total petroleum hydrocarbons (TPH) and toxicity characteristic leaching procedure (TCLP) metals results from the stockpiled waste indicated the material met non-hazardous Class 2 criteria. Disposal of the waste material was conducted in February 2004, under waste profile CG-25591, C-9. Waste was disposed of at Covel Gardens Landfill in San Antonio, Texas. Waste manifests are provided in Appendix B.
The following photographs show excavation activities at the site:
Excavation at SWMU B-30. November 24, 2003
Sidewalls of excavation at SWMU B-30. November 24, 2003
Debris excavated from SWMU B-30, stockpiled on-site. December 1, 2003
Excavated area at SWMU B-30, following soil disposal. March 1, 2004
Confirmation sampling was performed during January and May 2004. A total of 10 samples were collected, as shown in Figure B30‑9. Two samples (B30‑BOT01 and B30‑BOT02) were collected from the bottom of the excavated area. The remaining eight samples were sidewall samples.
Samples were analyzed for copper, nickel, and zinc (EPA method SW-6010B), and lead (EPA method SW-7421). These analytes exceeded background concentrations in RFI samples. Although barium and cadmium also exceeded background once each during the RFI, both exceedances were just slightly above bedrock background. Therefore, these metals are not believed to be a problem at the site and were excluded from the confirmation sampling suite. All closure samples were analyzed by Agricultural and Priority Pollutants Laboratory in Fresno, California. All closure results were below RRS1 criteria and are presented in Table B30‑3.