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SWMU B-1 RCRA Facility Investigation/Closure Report
Section 2 - Field Investigation
As outlined in the Environmental Encyclopedia site-specific work plan (Volume 1-2, SWMU B-1), the project RFI requirements were to drill three soil borings and to collect soil samples for analysis of bis(2-ethylhexyl)phthalate, butylbenzylphthalate, and di-n-butylphthalate only. These compounds were the only analytes exceeding RRS1 criteria during the 1995 investigation. All field activities were conducted in accordance with the Sampling and Analysis Plan (Volume 1-4, Field Sampling Plan and Quality Assurance Project Plan).
2.1.1 Geophysical Survey
In accordance with the approved work plan, a geophysical survey was not performed in association with the current investigation conducted for SWMU B-1. Results of the previous geophysical survey are described in Section 1.3.1.
2.1.2 Soil Gas Survey Samples
In accordance with the approved work plan, a soil gas survey was not performed in association with the current investigation conducted for SWMU B-1.
2.1.3 Surface Soil Samples
Surface soil samples were collected during drilling of soil borings at the site. Collection of these samples is described in further detail in Section 2.1.4.
2.1.4 Soil Boring Samples
Three borings (B1-SB4 through B1-SB6) were drilled in September 1996 and samples were collected for phthalate analysis only. These boreholes were drilled adjacent to B1-SB1, B1-SB2, and B1-SB-3 to depths of 27 feet, 22.5 feet and 38 feet respectively. The borings were drilled to delineate the SVOCs that were reported in analytical samples collected in 1995. Samples were submitted to ITS Laboratory in Richardson, Texas for analysis. However, in April 1999, EPA determined that ITS Laboratory results were invalid and could not be used. Therefore, resampling was conducted at this site in the spring of 2000.
While drilling at B1-SB5 in 1996, circulation was lost at 19 feet bgs. This boring was renamed B1-SB5A and abandoned to avoid loss of drilling equipment in the borehole. B1-SB5B was then drilled in an effort to obtain a sample at a depth of approximately 30 feet bgs. However, circulation was again lost at a similar depth, and the borehole was abandoned without collecting any additional samples. No groundwater was detected in any of the borings drilled in 1996.
To replace the 1996 analytical data, three additional soil borings were redrilled in the approximate locations of SB4, SB5A, and SB6 in late March and early April 2000. Sample locations are shown in Figure B1-4. Two soil samples were collected from RW-B1-SB5 (drilled immediately adjacent to B1-SB5A), and three soil samples were collected from RW-B1-SB4 and RW-B1-SB6. These samples include one surface soil sample (0 to 0.5 feet bgs) from each boring. A field duplicate was also collected at SB4. The two samples from RW-B1-SB5 were analyzed for SVOCs. All other samples were analyzed for bis(2-ethylhexyl)phthalate, butylbenzylphthalate, and di-n-butylphthalate only. APPL Laboratory in Fresno, California conducted the analyses using EPA Method SW-8270C.
Decontamination procedures, as well as sample collection, preparation, handling, and shipping, are described in the Field Sampling and Analysis Plan (Volume 1-4, Field Sampling Plan, Quality Assurance Project Plan). QA and QC samples were collected as described in the AFCEE QAPP (Volume 1-4, Quality Assurance Project Plan). Parsons with a Trimble Asset-grade GPS recorded sampling locations. Surveying methodologies are described in the Amendment to the Field Sampling Plan (Parsons ES, 2001b). Samples were sent to APPL Laboratory in Fresno, California for analysis of phthalates (EPA Method SW-8270C).
SWMU B-1 soil samples were collected on the same day as samples for SWMU B-5, SWMU B-6, and SWMU B-22. Field duplicates were submitted for RW-B6-SS02 (0.0 to 0.5 feet) and RW-B22-SS05 (0.0 to 0.5 feet); an MS/MSD was collected for RW-B22-SS05 (0.0 to 0.5 feet). A trip blank and equipment blank were also submitted.
2.1.5 Groundwater Samples
Perched groundwater was encountered in two borings, RW-B1-SB4 and RW-B1-SB6, and a grab sample was collected from each open borehole. Samples were collected on April 11, 2000 with a decontaminated Teflon bailer and submitted to APPL Laboratory for SVOC analysis (SW-8270C).
2.2.1 Geophysical Survey
In accordance with the approved work plan, a geophysical survey was not performed in association with the current investigation conducted for SWMU B-1. Results of the 1995 geophysical survey are summarized in Section 1.3.
2.2.2 Soil Gas Survey Samples
In accordance with the approved work plan, a soil gas survey was not performed in association with the current investigation conducted for SWMU B-1.
2.2.3 Surface Soil Samples
As described in Section 2.1.3, three surface soil samples were collected at the site in March and April 2000. These samples were tested for the three phthalate compounds that were found in 1995 during initial investigation of SWMU B-1. All concentrations were found to be below RLs and, therefore, RRS1 criteria were met. Detected concentrations are summarized in Table B1-3, and all results are presented in Appendix A.
2.2.4 Soil Boring Samples
In March 2000, bis(2-ethylhexyl)phthalate was detected in one subsurface rock sample at RW-B1-SB4; 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 SVOCs. Results are summarized in Table B1-3 and a full tabulation of all analytical results is provided in Appendix A.
2.2.5 Groundwater Samples
As described in Section 2.1.5, two grab groundwater samples collected at RW-B1-SB4 and RW-B1-SB6. The total depth of RW-B1-SB4 was 27 feet bgs, and the total depth of RW-B1-SB6 was 38 feet bgs. These samples were analyzed for SVOCs only. None of the SVOCs were detected in either of the samples. Results are provided in Appendix A.