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SWMU B-11 RCRA Facility Investigation Report
Section 2 - Field Investigation
As outlined in the
Environmental Encyclopedia site-specific Work Plan
(Volume 1-2, SWMU B-11), the project RFI requirements were to drill five
soil borings and to collect soil samples for VOCs, explosives, and metals
analyses. All field activities
conducted were in accordance with the Field Sampling and Analysis Plan (Volume
1-4, Field Sampling Plan, Quality Assurance Project Plan, and RL53 Addendum).
A summary of the analytical results is provided in
Appendix
A.
The geophysical survey conducted at the site in 1995 is described in Section 1.3. In accordance with the approved work plan, a geophysical survey was not performed in association with the current investigation conducted at SWMU B-11.
The soil gas survey conducted near the site is described in Section 1.3. In accordance with the approved work plan, a soil gas survey was not performed in association with the current investigation conducted for SWMU B-11.
Surface soil samples were collected in conjunction with the subsurface soil investigation conducted for SWMU B-11 and are described in Section 2.1.4.
On February 28 and 29, 2000, five soil borings were drilled to characterize subsurface soils at SWMU B-11. The borings were within the trench at locations shown in Figure B11-4. The borings were placed in areas considered to have the highest probability of contamination based on visual observations of surface conditions. Three samples were obtained from each boring; one soil sample was taken from the surface, one from near the middle of the boring, and one at total depth. Boring logs associated with boreholes conducted at SWMU B-11 are contained within Appendix B. Boring depths ranged from 8.5 to 20 feet bgs. Lithologic descriptions from the boring logs indicate silt and clay was encountered overlying limestone and marl, identified as the Upper Glen Rose Formation.
The analytes for the soil samples collected at SWMU B-11 were VOCs (SW-8260B), arsenic (SW-7060A), barium (SW-6010B), cadmium (SW-7131A), chromium (SW‑6010B), copper (SW6010B), lead (SW-7421), mercury (SW-7471A), nickel (SW-6010B), zinc (SW-6010B), and explosives (SW-8330). A total of 16 soil/rock samples (including one duplicate) were submitted for analysis. All samples were submitted to APPL Laboratories, Inc. of Fresno, California, except those for explosives analysis which were submitted to DataChem Laboratory in Salt Lake City, Utah.
Samples collected above the bedrock were obtained using a decontaminated hollow-stem auger and split-spoon sampler. Rock samples were obtained by air core using a decontaminated core barrel. All decontamination, sample preparation and handling followed those protocols established in the Field Sampling and Analysis Plan (Volume 1-4, Field Sampling Plan, Quality Assurance Project Plan). Environmental sampling also included the collection and submittal of QA and QC samples at those frequencies outlined 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 methodologies are described in the Amendment to the Field Sampling Plan (Parsons ES, 2001b). All sample locations and analytical data has been incorporated into the CSSA GIS.
In accordance with the approved work plan, groundwater samples were not collected in association with the current investigation conducted for SWMU B-11. No groundwater was encountered in the soil borings.
As described in Section 1.3, a geophysical survey was conducted at the site in April 1995. No anomalies suspected of being associated with subsurface waste were identified.
As described in Section 1.3, one soil gas sample was collected within SWMU B-11 in 1995, and two samples were located adjacent to SWMU B-11. At location “South Pasture 60,-60, the PCE concentration was 0.28 μg/L. To the north at location “South Pasture 60,-50,” PCE was detected at a concentration of 2.4 μg/L and to the south at “South Pasture 60,-70,” 0.51 μg/L PCE was detected, as indicated in Figure B11-5.
Surface soil samples were obtained during soil boring drilling and sampling. The results of the surface soil sampling program are combined with the discussion presented in Section 2.2.4.
Several compounds exceeded RRS1 criteria; however, the majority are suspected laboratory contaminants. Other compounds detected at levels slightly above RRS1 criteria include cadmium in three samples, and arsenic, barium, nickel, and zinc in one sample. Table B11-1 lists all of the analytes detected at SWMU B-11. As noted in Section 1.4, background levels are the RRS1 criteria for metals concentrations, and laboratory RLs are the RRS1 criteria for VOCs and explosives. Explosives were not detected in any of the samples. Appendix A contains all of the analytical results obtained from SWMU B-11 environmental samples.
Three VOCs were detected above RRS1 levels (laboratory RLs) in the environmental samples: chloroform, dichlorodifluoromethane, and methylene chloride. Methylene chloride, a common lab contaminant, was detected at levels above the RRS1 criteria in fourteen of the sixteen samples submitted; as shown on Table B11-1. The highest detected concentration of methylene chloride, 0.0417 mg/kg, occurred in sample B11-SB02 (9.5 – 10.5 ft.). Chloroform was detected above the RRS1 criterion in samples B11-SB04 (0.5-1.0 ft.), B11-SB04 (4.5-5.0 ft.), and B11-SB05 (8.0-8.5 ft.); however, chloroform was also detected in the blank associated with these samples. Dichlorodifluoromethane (freon) was detected above the RRS1 level in sample B11-SB01 (9.5-10.0 ft.).
Arsenic, barium, cadmium, chromium, nickel, and zinc levels slightly exceeded RRS1 comparison criteria (site background levels) in selected samples collected for the investigation. Zinc exceeded RRS1 criteria in B11-SB01 (0.5-1.0). Barium, chromium, nickel, and zinc levels exceeded RRS1 criteria in sample B11-SB03 (4.5-5.0 ft.). Arsenic exceeded the RRS1 level in sample B11-SB01 (19.5-20.0 ft.). Cadmium was above the RRS1 criteria in sample B11-SB02 (9.5-10.5 ft.).
The highest cadmium concentration (0.5 mg/kg) was detected in Glen Rose Limestone in sample B11-SB02 (9.5-10.5 ft.). The site background value for cadmium in the Glen Rose Limestone is 0.1 mg/kg. Arsenic was detected at 3.91 mg/kg in Glen Rose Limestone sample B11-SB01 (19.5-20.0 ft.), which is slightly above its site background value of 3.8 mg/kg.
The sample B11-SB03 (4.5-5.0 ft) had detections of barium, chromium, nickel and zinc. The nickel concentration of 8.14 mg/kg in limestone, exceeds its site background value of 6.8 mg/kg for the Glen Rose Limestone. Zinc was detected at 15.33 mg/kg in the Glen Rose Limestone, above the background value for this metal of 11.3 mg/kg. Chromium was also detected at 8.2 mg/kg, slightly above the background value of 8.1 mg/kg.
The most significant exceedance was that of barium at B11-SB03 (4.5-5.0 ft.). A concentration of 43.41 mg/kg was detected and the background concentration for Glen Rose Limestone is 10.0 mg/kg.
In accordance with the approved work plan, groundwater samples were not collected in association with the current investigation conducted for SWMU B-11.