[Home]
SWMU B-34 RCRA Facility Investigation Report
Section 2 - Field Investigation
As outlined in the Environmental Encyclopedia site-specific Work Plan (Volume 1-2, SWMU B-34), the objectives of the investigation were to conduct a geophysical survey, collect three surface soil samples, and drill and sample three borings at SWMU B-34, with the goal of closing the site under RRS1, if appropriate. All field activities were conducted in accordance with the field sampling and analysis plan (Volume 1-4, Field Sampling Plan, Sections 1-3).
Subsequent field activities completed for the RFI included a geophysical survey, collection of three surface soil samples, installation of three soil borings, and completion of one shallow hand auger boring. These investigation activities were conducted between March and October 1996. Soil/rock samples were analyzed by ITS Laboratories of Richardson, Texas. In April 1999, the EPA rejected the ITS analytical data. Therefore, three surface soil samples were re-collected and three soil borings were re-advanced at SWMU B-34 during March 2000.
Electromagnetic and ground penetrating radar geophysical surveys were conducted at SWMU B-34 in March 1996. Prior to collecting EM or GPR data, a grid system was established which encompassed the areas of suspected ground disturbance. These grids consisted of staked locations separated by intervals ranging from 25 to 100 feet, depending on the size of the area and the amount of obstructions, if any. The SWMU B-34 geophysical grid measured 40 feet by 260 feet with a 20-foot grid spacing.
EM data were collected at 2-foot intervals along transects that were separated by 20 to 50 feet using the established geophysical survey grid. EM measurements were taken using a Geonics EM31-DL ground conductivity meter, and recorded with a Polycorder data logger. The conductivity meter consists of transmitter and receiver coils that are separated by 12 feet. The instrument has a nominal depth of penetration of approximately 16 feet when operated in the vertical-dipole mode. The instrument measures both quadrature- and in-phase components of an induced magnetic field. The quadrature-phase component is a measure of apparent ground conductivity while the in-phase component is more sensitive to the presence of ferromagnetic metal. A lateral variation in apparent ground conductivity indicates a lateral change in subsurface physical properties (i.e., related to degree of disturbance). Apparent ground conductivity is measured with a precision of approximately ±2 percent of the full-scale meter reading which corresponds to approximately 2 milliSiemens per meter (mS/m). The in-phase component of the EM-31 is the response of the secondary to primary magnetic field measured in units of parts per thousand (ppt). The primary magnetic field is due to the current source from the EM-31. The secondary magnetic field is due to induced currents within conductive material in the subsurface.
Data were collected by setting the instrument to record in an automatic vertical dipole mode. Readings were taken at 0.5 second intervals which corresponded to a reading every 2 feet along a given transect. Both apparent ground conductivity (i.e., quadrature phase) and in-phase data were recorded. The operator aligned himself along a transect and, with the instrument parallel to the transect, paced between marked or staked stations separated by 20 feet. The variation in transect footage was related to the size of the site and the number of obstructions.
The EM-31 survey was completed according to the procedures described in Volume 1-4, Sampling and Analysis Plan, Section 1.1.2. Prior to the survey, a site near SWMU B-34 that was determined to be free of disturbances and anomalies was selected and marked to perform background checks and calibration. The background checks were also performed after the survey. All calibration and before and after background readings were recorded in the field logbook.
During each field day, data were transferred from the data logger to computer diskettes. The data were processed using DAT31 software (Geonics, LTD) and contoured using Surfer software. For EM data that was not collected using the data logger, values were recorded on a log sheet, manually entered into a computer file, and contoured using Surfer software. Contour maps for both apparent conductivity and in-phase data were created for each site.
In accordance with the approved work plan, a soil gas survey was not performed in association with the current investigation conducted for SWMU B-34.
On March 11, 1996, three surface soil samples were collected at SWMU B-34. The surface samples were submitted to ITS laboratories for VOC, SVOC, and metals analyses. During April 1999, the EPA declared the analyses associated with the three SWMU B-34 surface samples performed by ITS Laboratories to be unusable. Surface soil samples were recollected from the same locations as the original samples (Figure B34-4) during March 2000. Surface soil samples RW-B34-SS01 and RW-B34-SS02 were collected approximately 20 feet and 80 feet southeast of Building 28, respectively. Both samples were placed near or almost directly above the underground piping that drains Building 28. The third sample, RW-B34-SS03, was collected near the piping outfall area (Figure B34-4). These samples were submitted to APPL and to O’Brien & Gere Laboratories for metal, VOC, and SVOC analyses.
Each surface sample, as well as the subsurface samples discussed below, were analyzed for VOCs using EPA method SW-8260B and SVOCs using EPA method SW-8270C by APPL Laboratory in Fresno, California. O’Brien and Gere Laboratories in Syracuse, New York analyzed for barium, chromium, copper, nickel, and zinc by method SW-6010B, arsenic by method SW-7060A, cadmium by method SW-7131A, lead by method SW-7421, and mercury by method SW-7471A. An analytical results summary is provided in Appendix B. Equipment decontamination procedures, as well as sample collection, preparation, handling, and shipping protocols, are described in the Sampling and Analysis Plan (Volume 1-4, Field Sampling Plan and 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 after it has been approved by AFCEE and CSSA.
The soil/rock samples obtained from the SWMU B-34 area consisted of either Crawford and Bexar soils or Upper Glen Rose Limestone material. The Crawford and Bexar soils were identified to consist of silty to clayey soils together with minor amounts of organic material and caliche. The soils were dark brown (7.5YR3/3 on the Munsell® Soil Color Charts). PID readings were negative for organic vapors associated with soil samples collected.
The analyses of the subsurface samples collected in 1996 and performed by ITS Laboratories, Inc., were deemed invalid 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-34). On August 22 and 23, 2000, three soil borings were advanced adjacent to the surface soil sampling locations. Soil and rock samples were obtained from borings RW-B34-SB02, RW-B34-SB03, and RW-B34-SB04, and rock samples only were obtained from RW-B34-SB01. The three soil borings were designated RW-B34-SB01, RW-B34-SB02, and RW-B34-SB03. Borings RW-B34-SB01 and RW-B34-SB02 were placed near locations associated with surface samples RW-B34-SS01 and RW-B34-SS02, respectively. Soil boring RW-B34-SB03 was placed approximately 40 feet north of RW-B34-SS03 (Figure B34-4). Boring RW-B34-SB01 was advanced to 12.9 feet bgs, boring RW-B34-SB02 was advanced to 10.2 feet bgs, and boring RW-B34-SB03 was advanced to 13.8 feet bgs. A total of seven samples were collected from the three borings. Two samples were collected from both borings RW-B34-SB01 and RW-B34-SB02, while three samples were collected from boring RW-B34-SB03. Samples were analyzed for VOCs, SVOCs, and metals, using the methods and laboratories outlined in Section 2.1.3.
Soil samples were obtained continuously from the ground surface to the boring termination depth. Soil samples were screened for organic vapors utilizing olfactory responses and headspace analysis conducted with a photo-ionization detector (10.2 ev/amp) calibrated with 100 ppm isobutylene.
Soil boring logs from the borings advanced in 1996 are presented in Appendix A. As provided in the work plan, new boring logs were not to be created, 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 lithologies were noted.
Groundwater grab samples were planned only if groundwater was encountered during soil boring drilling. Since no groundwater was encountered, grab samples were not collected.
The presence of Building 28 hindered the effectiveness of geophysical techniques in close proximity to the building. The geophysical survey did not reveal evidence of anomalies associated with past waste management activities. The geophysical survey did not identify the location of the subsurface pipe composing SWMU B-34.
The geophysical surveys revealed no evidence of subsurface anomalies related to past waste disposal activities. There was little variation in the data that were recorded during the EM survey, which can be interpreted as homogenous and consistent soil and bedrock profiles throughout the SWMU (Figure B34-5 and Figure B34-6). In-phase readings during the EM survey ranged from a minimum of approximately -4.0 ppt, to a maximum of 18.2 ppt, except in the northwest corner of the site. Interference from Building 28 caused in-phase readings in this area to reach a minimum of -9.1 ppt. Quadrature-phase readings ranged from a low of 31.6 mS/m to a high of 68.1 mS/m.
In accordance with the approved work plan, a soil gas survey was not performed in association with the investigation conducted for SWMU B-34.
Four surface soil samples, including one soil boring sample obtained from 0 to 0.5 feet (RW-B34-SB03, 0-0.5 ft.), were collected at SWMU B-34 and analyzed for VOCs, SVOCs, and metals. As shown in Table B34-1, no VOCs or SVOCs were detected in surface soil above RRS1 levels. However, chromium, copper, lead, nickel, and zinc levels exceeded background concentrations. Analytical results are listed within Appendix B.
Sample RW-B34-SS01 reported concentrations of 58.6 mg/kg, 52.8 mg/kg, 169.2 mg/kg, and 611.2 mg/kg for chromium, copper, zinc, and lead, respectively. As shown in Table B34-1, the RRS1 standards (background values) for chromium, copper, zinc, and lead in CSSA soils are 40.2 mg/kg, 23.2 mg/kg, 73.2 mg/kg, and 84.5 mg/kg, respectively. Sample RW-B34-SS02 exceeded background concentrations for chromium, copper, nickel, and zinc, with reported concentrations of 81 mg/kg, 88.6 mg/kg, 45.2 mg/kg, and 168 mg/kg for these constituents, respectively. The RRSI standard (background value) for nickel is 35.5 mg/kg. Sample RW-B34-SS03 had reported concentrations of 96 mg/kg, 135.8 mg/kg, 204.2 mg/kg, and 110.8 mg/kg for chromium, copper, zinc, and lead, respectively. Copper was detected at 26.3 mg/kg in the surface soil sample at RW-B34-SB03.
Surface soil samples exceeded the Texas-Specific Background Concentrations for chromium, copper, zinc, and lead in all three surface samples and for copper in the RW-B34-SB03 sample collected from 0 to 0.5 feet. The Texas-Specific Background Concentrations for chromium, copper, zinc, and lead are 30 mg/kg, 15 mg/kg, 30 mg/kg, and 15 mg/kg, respectively. The Texas-Specific Background Concentrations are provided in Texas Risk Reduction Program (TRRP) Rule (30 TAC 350).
Three soil borings were advanced at the locations shown on Figure B34-4. Subsurface borings were performed immediately adjacent to the estimated location of the subsurface pipe associated with SWMU B-34.
Although no VOCs were detected above RRS1 criteria in any of the samples, several metals concentrations in most samples exceeded background and bis(2‑ethylhexyl)phthalate in four samples exceeded the RRS1 criteria. Results are summarized in Table B34-1 and a complete list of analytical results is included in Appendix B. Bis(2-ethylhexyl)phthalate was detected at RW-B34-SB01 (4.5-5.0 feet and 12.0-12.5 feet), RW-B34-SB02 (8.5-9.0 ft), and RW-B34-SB03 (13.0-13.5 ft) at concentrations ranging from 3.8 to 14 mg/kg.
Metals concentrations exceeded RRS1 standards in six of the seven subsurface soil samples collected. Metals which exceeded RRS1 standards were barium, chromium, copper, nickel, zinc, cadmium, and lead.
Barium concentrations exceeded background values in four samples collected. RW‑B34-SB02 (3.5-4.0 ft) consisted of Crawford and Bexar soils and reported barium at a concentration of 219.0 mg/kg, greater than the background value of 186 mg/kg. The remaining three samples that exceeded background for barium consisted of Glen Rose limestone samples. The background value of 10 mg/kg was exceeded in samples RW-B34-SB02 (8.5-9.0 ft), RW-B34-SB03 (7.5-8.0 ft), and RW-B34-SB03 FD1 (7.5-8.0 ft) at reported concentrations of 13.2 mg/kg, 28.2 mg/kg, and 22.4 mg/kg, respectively. None of the concentrations reported for barium exceed the Texas-Specific Background Concentration for barium of 300 mg/kg.
Only one sample reported a chromium concentration exceeding the background value of 40.2 mg/kg for CSSA soils material. The sample from RW-B34-SB02 (3.5 to 4.0 ft) reported a chromium concentration of 68.0 mg/kg. This result does exceed the Texas-Specific Background Concentration for chromium of 30 mg/kg. The same sample (RW-B34-SB02, 3.5 to 4.0 ft) reported the only copper concentration exceeding the background value in CSSA soils material of 23.2 mg/kg for copper, with a reported concentration of 45.0 mg/kg. This reported copper concentration exceeds the Texas-Specific Background Concentration of 15.0 mg/kg for copper. This sample had the only exceedance of nickel, reported at 36.6 mg/kg, slightly above the soils background of 35.5 mg/kg and above the Texas-specific background concentration for nickel of 10 mg/kg.
Zinc was reported in excess of the applicable background concentration in six of the seven subsurface samples collected. The background values for zinc are 73.2 mg/kg in soils and 11.3 mg/kg in Glen Rose Limestone material. Sample RW-B34-SB02 (3.5-4.0 ft) consisted of Crawford and Bexar soils and reported zinc at a concentration of 109.2 mg/kg. Glen Rose Limestone samples RW-B34-SB01 (4.5 to 5.0 ft), RW-B34-SB01 (12.0 to 12.5 ft), RW-B34-SB02 (8.5 to 9.0 ft), RW-B34-SB03 (7.5 to 8.0 ft), and RW-B34-SB03 FD1 (7.5 to 8.0 ft) reported zinc concentrations ranging from 20.2 mg/kg to 45.6 mg/kg, respectively. The reported concentrations from RW-B34-SB01 (12.0 to 12.5 ft) of 45.6 mg/kg and RW-B34-SB02 (3.5 to 4.0 ft) of 109.2 mg/kg exceed the Texas-Specific Background Concentration for zinc of 30 mg/kg.
Cadmium was reported in two Glen Rose Limestone samples at concentrations slightly above the background value of 0.1 mg/kg. Samples RW-B34-SB01 (4.5 to 5.0 ft) and RW-B34-SB01 (12.0 to 12.5 ft) reported cadmium at 0.13 mg/kg and 0.22 mg/kg, respectively.
Lead was reported in two Glen Rose Limestone samples at concentrations above the background value of 5.5 mg/kg. Samples RW-B34-SB03 (7.5 to 8.0 ft) and RW-B34-SB03 FD1 (7.5 to 8.0 ft) reported lead at concentrations of 14.95 mg/kg and 17.25 mg/kg, respectively. Only the reported concentration from RW-B34-SB03 FD1 (7.5 to 8.0 ft) exceeds the Texas-Specific Background Concentration of 15.0 mg/kg for lead.
Groundwater was not encountered during soil boring drilling; therefore, no groundwater samples were collected.