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Final SWMU B-12 RCRA Facility Investigation Report
Section 2 - Field Investigation
As outlined in the Environmental Encyclopedia site-specific work plans (Volume 1-2, SWMU B-12), project RFI requirements were to collect the surface and subsurface soil samples in locations biased towards those areas which exhibit evidence of past waste management practices. All field activities were conducted in accordance with the Field Sampling and Analysis Plan (Volume 1-4, Field Sampling Plan and Quality Assurance Project Plan).
A geophysical survey was conducted at the site in 1995, as described in Section 1.3. No additional geophysical surveys were conducted during the current investigation.
Soil gas survey samples were not collected in association with the investigation conducted for SWMU B-12.
Three surface soil samples were collected in September 1996. Samples were submitted to ITS Laboratories for analysis. The analyses of the subsurface samples that were collected in 1996 were deemed unusable by the EPA in 1999. A Work Plan Amendment was subsequently created to replace the invalid laboratory data (RL17 Work Plan Amendment for Data Quality Rework at SWMU B-12). Surface samples were re-collected in March 2000 as part of the soil borings sampled. Discussion of the soil boring samples collected in the top one foot of soil are discussed in Sections 2.1.4 and Sections 2.2.4, below.
On August 30 and September 3, 1996, four soil borings were advanced at SWMU B-12. Soil/rock samples were collected on a continuous basis from each boring for lithologic logging. Samples were visually examined to identify soil/rock type and to identify evidence of contamination. Samples were screened using a PID as an additional measure to identify evidence of contamination. Samples from these original borings were submitted to ITS Laboratories for VOCs, SVOCs, explosives, and metals analyses. However, laboratory analyses were deemed invalid by the EPA in 1999.
Four replacement soil borings were advanced on March 15, 2000, and three samples were collected from each boring. Figure B12-4 shows the locations of the borings, which were drilled within 10 feet of the 1996 boring locations. The 1996 borings were located at the base of the embankment for two reasons. First, all visual evidence of waste was located within the embankment, and no evidence of waste was observed in the flat-lying area. The bottom of the embankment is the closest location to the observed waste accessible to drilling rigs. Second, in 1996 when the drilling was initially completed at the site, the flat-lying area was underwater and inaccessible for drilling. Soil boring depths ranged from 10 to 11 feet bgs.
Each sample was analyzed for VOCs using EPA method SW-8260B and for SVOCs using EPA method SW-8270C by APPL Laboratory in Fresno, California. Explosives were analyzed using EPA method SW-8330 by DataChem Laboratory in Salt Lake City, Utah; and barium, chromium, copper, nickel, and zinc were analyzed by method SW-6010A, arsenic by method SW-7060A, cadmium by SW-7131A, lead by SW-7421, and mercury by SW-7471A by O’Brien and Gere Laboratories in Syracuse, New York. A summary of analytical results is presented in Appendix A. A total of twelve environmental samples, not including three field duplicates, one matrix spike, one spike duplicate, one equipment blank, and one trip blank, were submitted for analysis with respect to SWMU B-12.
Equipment decontamination procedures, as well as sample collection, preparation, handling, and shipping protocols, are described in the Field Sampling and Analysis Plan (Volume 1-5, Quality Assurance Project Plan). QA and QC samples were collected as described in the AFCEE QAPP (Volume 1-4, Quality Assurance Project Plan). 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 database.
Soil boring logs from the borings advanced in 1996 are presented in Appendix B. As per the Re-Work Plan (RL17 Work Plan Amendment for Data Quality Rework at SWMU B-12), new borings were not to be recorded, but the differences between the 1996 and 2000 borings were to be noted. The borings advanced in 2000 were advanced adjacent to the 1996 borings, and no significant differences in the borings were noted.
In accordance with the approved work plan, groundwater samples were not collected in association with the investigation conducted at SWMU B-12.
A geophysical survey was not performed at this site during the current investigation. As described in Section 1.3, no anomalies were identified in the flat-lying portion of the site that was surveyed in 1995. The embankment was not included in the 1995 geophysical survey due to the amount of scrap metal on the surface in that area.
In accordance with the approved work plan, a soil gas survey was not conducted in association with the investigation of SWMU B-12.
As described in Section 2.1.3, three surface soil samples were collected at the site. These samples were collected at RW-B12-SB01, RW-B12-SB03, and RW-B12-SB04 from 0 to 1.0 feet bgs as part of the subsurface soil investigation. Detected concentrations are summarized in Table B12-1 and all results are presented in Appendix A. None of the analytes exceeded RRS1 criteria at RW-B12-SB01 or RW-B12-SB02. However, several analytes at RW-B12-SB04 did exceed RRS1 levels. Results are described in detail in Section 2.2.4.
Analytical results associated with soil and/or rock samples collected for the investigation are provided in Appendix A. Table B12-1 presents a summary of detected constituents together with a listing of applicable RRS1 standards. Several constituents were detected at concentrations exceeding RRS1 standards as detailed in the following paragraphs.
No explosive compounds were detected in any of the subsurface soil and/or rock samples. Several VOCs were detected in samples collected at SWMU B-12; however, all concentrations were below RLs. Analytes detected included toluene, bromobenzene, and methylene chloride. As described in Section 4.1.5 of the Risk Assessment Technical Approach Document, AFCEE RLs are equivalent to PQLs; therefore, the subsurface soil meets RRS1 criteria for VOCs and explosives.
Three SVOCs were also detected in SWMU B-12 samples; however, only two compounds, fluoranthene and bis(2-ethylhexyl)phthalate, were detected above RLs. The concentration of fluoranthene detected was only slightly in exceedance of the RL, reported at 0.75 mg/kg in RW-B12-SB04 (0 to 0.5 feet bgs) with an RL of 0.7 mg/kg. Bis(2-ethylhexyl)phthalate exceeded RRS1 criteria in subsurface samples from RW-B12-SB01 (3.5 to 4.0 feet bgs and 9.0 to 9.5 feet bgs), RW-B12-SB02 (5.5 to 6.0 feet bgs and 9.5 to 10.0 feet bgs), RW-B12-SB03 (10.0 to 10.5 feet bgs) and RW-B12-SB04 (0 to 0.5 feet bgs, 4.5 to 5.0 feet bgs, and 9.0 to 9.5 feet bgs).
Metals exceeding RRS1 in soil and rock samples included: barium, copper, lead, mercury, nickel, and zinc. Nine samples collected from the borings exceeded the RRS1 soil and rock criteria for various metals. The highest metals levels were detected in the surface soil sample collected at RW-B12-SB04.
At RW-B12-SB01, all surface sample metal results met RRS1 criteria. Zinc levels slightly exceeded the background level of 11.3 mg/kg in samples collected at 3.5 to 4.0 feet bgs (19.2 mg/kg), 3.5 to 4.0 feet bgs (FDI) (16.1 mg/kg) and 9.0 to 9.5 feet bgs (14.7 mg/kg). These concentrations are below the Texas-specific median concentration of 30 mg/kg (30 TAC 350.51(m)).
The concentration of nickel (10.6 mg/kg) in a duplicate sample RW-B12-SB01 (3.5-4 ft.) exceeded the background level of 6.8 mg/kg; however, the nickel concentration in the original sample was only 6 mg/kg.
At RW-B12-SB02, barium, zinc, and lead were detected above background levels. Barium was detected at 10.8 mg/kg, only slightly above the background level of 10.0 mg/kg. Zinc was reported at 21.8 mg/kg, above the background of 11.3 mg/kg, and lead was reported at 7.08 mg/kg, slightly above the background level of 5.5 mg/kg.
At RW-B12-SB03, barium, cadmium, lead, and zinc exceeded RRS1 criteria for Glen Rose Limestone. The sample collected from 1.0 to 1.5 feet bgs, which consisted of weathered limestone, contained 32.2 mg/kg barium, 0.10 mg/kg cadmium, 53.04 mg/kg lead, and 36.6 mg/kg zinc. These concentrations all exceed Glen Rose limestone background levels. However, because this sample consisted of weathered limestone, these background levels are not appropriate. These concentrations do not exceed the soil background levels and this sample was re-designated as a soils sample. The sample collected from 10 to 10.5 feet bgs had a zinc concentration of 15.9 mg/kg, and the background level is 11.3 mg/kg.
As mentioned previously, the highest metal levels were detected at RW-B12-SB04 (0 to 0.5 ft bgs). In this sample, RRS1 exceedances included copper at 54.4 mg/kg, lead at 773.2 mg/kg, and 0.65 mg/kg mercury. Zinc exceeded background in the samples collected at 4.5 to 5.0 feet bgs (25.8 mg/kg) and 9.0 to 9.5 feet bgs (12.8 mg/kg). The field duplicate of RW-B12-SB04 (4.5-5) had an exceedance of 7.0 mg/kg, slightly above the background level of 6.8 mg/kg, but the original of this sample reported zinc at 4.1 mg/kg. Both of these concentrations are below the Texas-specific median concentration of 30 mg/kg.
Zinc was detected above RRS1 criteria in various samples collected from three of the four soil borings conducted for the investigation. The samples that exceeded RRS1 criteria for zinc were: RW-B12-SB01 (3.5-4.0), RW-B12-SB01 Field Duplicate (3.5-4.0), RW-B12-SB01 (9.0-9.5), RW-B12-SB02 (0.5-1.0), RW-B12-SB03 (10.0-10.5), RW-B12-SB04 (4.5-5.0), and RW-B12-SB04 (9.0-9.5). The background level for zinc in the Glen Rose limestone at CSSA was calculated to be 11.3 mg/kg and for soils is 73.2 mg/kg. The highest concentration of zinc among the Glen Rose samples that exceeded RRS1 criteria was 25.8 mg/kg in sample RW-B12-SB04 (4.5-5.0). The lowest zinc concentration among samples that exceeded RRS1 criteria was 12.8 mg/kg concentration reported from RW-B12-SB04 (9.0-9.5). The highest concentration among soil samples was 182.5 mg/kg detected in RW-B12-SB04 (0-0.5).
In accordance with the approved workplan, no groundwater samples were collected during the investigation conducted at SWMU B-12. Groundwater was not encountered in any of the soil borings.