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SWMU B-8 RCRA Facility Investigation Report
Section 2 - Field Investigation
As outlined in the Environmental Encyclopedia site-specific work plans (Volume 1-2, SWMU B-8), the project RFI requirements were to excavate and inspect the soil to remove UXO and scrap metal, and advance three soil borings to collect soil samples for VOCs, explosives, and metals analyses. All decontamination, sample preparation, and sample handling followed those protocols established in the Field Sampling and Analysis Plan (Field Sampling Plan, Quality Assurance Project Plan, and RL33 Addendum).
In addition to the RFI, interim measures are also being taken to address stockpiled soil at the site in accordance with the consent order. Results of sampling associated with the interim measures are also described in this RFI report because they are important for site characterization. However, plans for treatability studies associated with these soils are discussed in the Soil Pile Disposition Assessment Report.
The geophysical survey conducted at the site in 1995 is described in Section 1.3. No additional geophysical surveys were conducted during the current investigation at the site.
A soil gas survey was not conducted during the current investigation at SWMU B-8.
On August 21 and 22, 1996, three soil borings were advanced at SWMU B-8. Three samples were collected from each boring. Each soil sample was analyzed for VOCs, explosives, arsenic, barium, cadmium, chromium, copper, lead, mercury, nickel, and zinc. No indication of surface or buried waste management activities was evident during the field effort. Headspace readings using a PID indicated that a VOC was present in the core samples in concentrations as great as 178 ppm. No visible staining was observed. Kerosene had recently been used to start controlled vegetation burning in the area.
Data from these three original borings were submitted to ITS Laboratories in Richardson, Texas. However, due to questionable activities by ITS, these data were not considered usable, as per a memo from the USEPA in April 1999.
Three replacement soil borings were advanced on March 24, 2000, and three samples were collected from each boring. Figure B8-4 shows the locations of the borings, which were drilled within 10 feet of the 1996 boring locations. The borings were advanced to a total depth of between 9 to 14 feet bgs. Eleven soil/rock samples (including two duplicates) were submitted for analysis. Each soil sample was analyzed for VOCs (EPA method SW-8260B); explosives (SW‑8330); barium, chromium, copper, nickel, and zinc (SW-6010B); arsenic (SW-7060A); cadmium (SW-7131A); lead (SW-7421); and mercury (SW-7471A). These samples were submitted to APPL Laboratory in Fresno, California for VOC analysis, O'Brien & Gere Laboratories in Syracuse, New York for metals analyses, and DataChem Laboratory in Salt Lake City, Utah for explosives analyses. The samples were collected from the top of each boring (0.5‑1.0 feet bgs), the middle of each boring (~5 to 8 feet bgs), and the terminus of each boring (~9 to 14 feet bgs). Because the bottles containing samples RW-B8-SB02 (11.5-12 ft) and the duplicate of RW-B8-SB03 (8-8.5 ft) for VOC analysis broke during shipment, this analysis was cancelled on the two samples.
Boring logs were initially created during the 1996 drilling. If differences were noted during the 2000 drilling, they were added to the 1996 log. No discernable evidence of contamination was noted during the year 2000 sampling activities, and no elevated PID readings were observed.
All sampling points were surveyed by Parsons ES using a Trimble Asset-grade GPS. Surveying methodology is described in the Amendment to the Field Sampling Plan (Parsons ES, 2001b). All sample locations and analytical data will be incorporated into the CSSA GIS after approval by AFCEE and CSSA.
As described in Section 2.1.3, surface soil samples were collected at each boring location at a depth of 0.5 to 1.0 feet bgs. Each sample was analyzed for VOCs (SW‑8260B) by APPL Laboratory; explosives (SW-8330) by DataChem Laboratory; barium, chromium, copper, nickel, and zinc (SW-6010B); arsenic (SW-7060A); cadmium (SW‑7131A); lead (SW-7421); and mercury (SW-7471A), by O’Brien & Gere Laboratories.
Groundwater sampling was not conducted at SWMU B-8 during the current investigation. No groundwater was encountered in the SWMU B-8 soil borings.
The anomaly detected east of the burn area was excavated on August 26, 1997. This anomaly was excavated to identify and remove any UXO potentially present at the site. UXO specialists from UXB International conducted the excavation activities and used Schonstedt magnetometers to aid in identifying the location and extent of the anomaly. Sifting of the excavated soil was planned but not carried out based on the findings, which are detailed in Section 2.2.6.
2.1.7 Soil Stockpile Disposition Samples
Samples of B-8 stockpiled soil were initially collected in 1997 and analyzed by ITS. As described in Section 2.1.3, these data are considered unusable for site characterization or closure purposes. On April 21, 2000, three soil samples were re-collected from the stockpile at SWMU B‑8 to provide information for the assessment of treatment/disposal options. Although this soil was not sifted, the sample identifications are B8-SIFT01, B8-SIFT02, and B8-SIFT03. These samples were analyzed for barium, chromium, copper, nickel, and zinc (SW-6010A); arsenic (SW-7060A); cadmium (SW-7131A); lead (SW-7421); and mercury (SW-7471A). In addition, one sample (B8-SIFT01) was also analyzed for VOCs (SW-8260B) and explosives (SW-8330). VOCs and metals analyses were conducted by APPL Laboratory, and explosives analyses were conducted by DataChem Laboratory. Samples were collected at random depths and locations in the pile, using an EPA-approved random sampling methodology for stockpiles described in 40 CFR 761.
In addition, two soil samples were collected from the stockpile on January 25, 2001 to provide information regarding the leachability of contaminants. Results of these leachability tests are included in the Soil Pile Disposition Assessment Report.
A geophysical survey was not performed at this site during the current RFI. As described in Section 1.3, one anomaly suspected of being associated with past waste management activities was identified during a geophysical survey conducted at the site in 1995.
A soil gas survey was not conducted at SWMU B-8.
Several VOCs were detected in subsurface rock samples at SWMU B-8; however, all concentrations were below RLs. As described in Section 4.1.5 of the Risk Assessment Technical Approach Document, AFCEE RLs are equivalent to PQLs; therefore, the site meets RRS1 criteria for VOCs. Results are summarized in Table B8-1 and a full tabulation of all analytical results is provided in Appendix B.
Explosive compounds were not detected in any of the samples, and therefore, are not listed in Table B8-1. Non-detect results are provided in Appendix B.
Several metals were detected at concentrations above RRS1, or background, levels in subsurface samples collected at soil borings RW-B8-SB02 and RW-B8-SB03. At SB02, barium, copper, and lead were detected above background concentrations in the 7 to 7.5 feet bgs sample; and zinc was detected above background levels in both the 7 to 7.5 foot bgs and 11.5 to 12.0 feet bgs samples. However, the exceedance in the 11.5 to 12.0 foot bgs sample was slight: 14.0 mg/kg zinc detected with a background concentration of 11.3 mg/kg. Zinc concentrations slightly above CSSA background levels have been detected in Glen Rose limestone at several other sites and may be indicative of an inappropriate CSSA background concentration for this metal. The Texas-specific median background concentration (30 TAC §350.51(m)) for zinc is 30 mg/kg. Only copper and zinc levels in the 7 to 7.5 feet bgs sample at SB02 exceeded Texas-specific background levels.
At SB03, barium slightly exceeded the background concentration of 10.0 mg/kg at both 8 to 8.5 feet bgs (12.7 mg/kg) and 13.5 to 14 feet bgs (11 mg/kg). In addition, chromium (11.7 mg/kg) and zinc (13.8 mg/kg) slightly exceeded background levels in the 13.5 to 14 feet bgs sample. Like the zinc background value discussed above, the Texas-specific median concentrations for barium (300 mg/kg) and chromium (30 mg/kg) are higher than the CSSA-specific concentration. None of the SB03 Glen Rose sample concentrations exceeded Texas-specific median background concentrations.
As described in Section 2.1.4, three surface soil samples were collected at the site. Similar to the rock samples, several VOCs were detected in surface soils; however, all concentrations were below RLs and, therefore, RRS1 criteria. Detected concentrations are summarized in Table B8-1, and all results are presented in Appendix B. No explosives were detected in surface soil.
Metals above CSSA background concentrations for CSSA soils were detected in each of the surface soil samples. The highest concentrations were detected in the duplicate sample collected at SB02 (0.5-1.0 feet bgs), where barium (10,814 mg/kg), copper (110,240 mg/kg), lead (156,640 mg/kg), and zinc (40,638 mg/kg) all greatly exceeded CSSA background soils levels. The lowest metals levels were detected at SB03 (0.5-1.0 feet bgs), where only barium (224.4 mg/kg), copper (112.1 mg/kg), and lead (443 mg/kg) exceeded CSSA background. All samples also exceeded Texas-specific background levels.
Groundwater sampling was not conducted at SWMU B-8.
UXO identification work was initiated at the site on August 26, 1997. A geophysical anomaly was excavated in preparation for sifting activities planned to remove UXO and scrap metal. However, during excavation activities, no UXO was found. Only two concrete slabs that contained rebar were removed from the site, with a minor amount of small projectiles found on the surface. Therefore, at SWMU B-8, no soil was sifted and no additional metal debris was removed. A small stockpile of soil is located at SWMU B-8, which includes the material excavated when the concrete slabs were discovered.
The excavated soils are stockpiled in a single pile with a radius of approximately 33 feet and height of approximately 2 feet. The pile is approximately cylindrical and is estimated to contain about 250 cubic yards of soil.
2.2.7 Soil Stockpile Disposition Samples
Stockpiled soil sample results are summarized in Table B8-2, and a complete tabulation of all results is provided in Appendix B.
VOCs and an explosive compound were detected in the only sample analyzed for VOCs and explosives, B8-SIFT01. Low levels of methylene chloride, TCE, and 2,4,6-TNT were all detected; however, all concentrations were below AFCEE RLs. In addition, none of those compounds were detected in surface or soil boring samples.
Metals concentrations in all three sifted soil samples exceeded CSSA background levels. Concentrations of copper and lead exceeded background in all three samples. In addition, barium and zinc levels exceeded CSSA background levels in B8-SIFT02 and B8-SIFT03. Maximum detected concentrations were as follows: barium, 2,393.4 mg/kg; copper, 2,155.34 mg/kg; zinc, 411.86 mg/kg; and lead, 3892.36 mg/kg.