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SWMU B-13 RCRA Facility Investigation Report
Section 2 - Field Investigation
2.1 - Field Actions
Records review indicated that SWMU
B-13 was used as a construction debris disposal
area. A field survey completed in
September of 1993 indicated an area where miscellaneous solid waste was
disposed. This area has been covered
and semi-compacted, but in several areas the cover has eroded, revealing the waste
debris beneath the surface of the ground.
In an effort to characterize the site and determine its readiness for RRS1 closure, a geophysical investigation was performed in March 1996. An additional survey was performed in April 1996 for verification of the anomalies detected. In 1996, four soil borings were drilled to assess the extent of contamination for metals, VOCs, and SVOCs. However, the analytical data associated with the subsurface samples were rejected by the EPA in 1999 due to questionable practices by ITS Laboratory. Subsurface sampling was repeated in 2000, in accordance with the SWMU B-13 Rework Work Plan (Volume 1-2). The small intermittent stream was not sampled since it only flows during high precipitation events.
2.1.1 Geophysical SurveyAn electromagnetic (EM) geophysical survey was performed on March 17, 1996. Prior to collecting EM or GPR data, a 360 by 360 feet grid system was established at the site which encompassed the areas of suspected ground disturbance. These grids consisted of staked locations separated by intervals of 20 feet (Figure B13-4). An additional survey was performed on April 3, 1996, to verify and extend the anomaly map generated by the March 1996 field effort. In-phase and conductivity data were mapped using 2 ppt and 5 mS/m, respectively.
EM data were collected at 2-foot intervals along transects that were separated by 20 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 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 the SWMU 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, soil gas survey samples were not collected in association with the current investigation conducted for SWMU B-13.
Surface soil samples were collected from the top foot of soil during the advancement of the soil borings. These surface soil samples are described below, with the associated boring from which they were collected.
2.1.4 Subsurface Soil SamplesOn August 27 and 28, 1996, four soil borings (B13-SB1 through B13-SB4) were advanced to assess contamination levels (Volume 1-1, RL17 Work Plan Addendum). The soil borings were advanced in locations biased to further investigate the geophysical survey anomalies reported (Figure B13-4). The analyses of the subsurface samples that were collected in 1996 were performed by ITS Laboratories, Inc., and 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-13).
On March 8 and 9, 2000, four soil borings (RW-B13-SB1 through RW-B13-SB4) were advanced adjacent to the locations where borings were advanced in 1996 (Figure B13-4). Samples collected above 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). Samples were collected in a collaborative effort from SWMUs B-13 and B-29. Therefore, MS and MSD samples were collected from SWMU B-29 for the analytical batch in which the SWMU B-13 samples were analyzed.
All soil boring locations were adjacent to the soil borings completed in August 1996 to further investigate the geophysical anomalies detected (Figure B13-4). SB01 and SB02 were completed in the northwest portion of the site, in an area identified as a geophysical anomaly; SB03 was drilled in the central portion of the site, adjacent to a waste pile, and SB04 in the south-central portion of the site adjacent to another geophysical anomaly. The soil borings were completed to the same total depth as the borings in the 1996 field effort, which ranged from 9.5 to 12.5 feet bgs.
Soil boring logs from the borings advanced in 1996 are presented in Appendix B. In accordance with the Rework Work Plan (RL17 Work Plan Amendment for Data Quality Rework at SWMU B-13), new borings were not to be recorded, but the differences between the 1996 and 2000 borings were to be noted. No significant differences in the borings were observed.
Each soil boring was sampled at three discrete intervals. RW-B13-SB01 was sampled at 0.5-1.0 feet, 6.5-7.0 feet, and 11.5-12.0 feet bgs. RW-B13-SB02 was sampled at 0.5-1.0 feet, 6.5-7.0 feet, and 10.0-10.5 feet bgs. Samples were collected at depths of 0.5-1.0 feet, 4.0-4.5 feet, and 8.5-9.0 feet bgs at RW-B13-SB03. RW-B13-SB04 had sample depths of 0.5-1.0 feet, 3.5-4.0 feet, and 9.5-10.0 feet bgs. Some of these sampling depth intervals vary slightly from the depth intervals sampled in 1996 due to sample recovery; however, the samples were collected in the same type of rock or soil as in 1996.
Samples to be analyzed for VOCs (SW8260B) and SVOCs (SW8270) were submitted to APPL Laboratories in Fresno, California on March 8, 2000. Samples analyzed for metals (SW6010B, SW7060A, SW7131A, and SW7471) were submitted to O’Brien and Gere Laboratories in East Syracuse, New York on March 8, 2000. A total of 12 environmental samples, three field duplicates, two matrix spike samples, two spike duplicates, two equipment blanks, and two trip blanks were submitted for analysis.
The SWMU B-13 soil samples originated from the Krum Complex soil. In general, the soils were plastic, moist, silty clays with small pebbles. At the time of sampling, no contamination was observed either visually or with the PID. Soil thickness of the Krum Complex soil ranged from 1.7 feet in RW-B13-SB1, to 5 feet in RW-B13-SB2. Surficial soils were underlain by pinkish white and pale brown competent limestone bedrock. Overall, this massive limestone was dry, hard, and fossiliferous.
At borings RW-B13-SB01 and RW-B13-SB02, waste material was encountered to a depth of approximately 7 feet bgs. Waste material found in the core sample included wood, wire, and scrap metal. At RW-B13-SB03, a charred zone with an ashy appearance was encountered at a depth of 2.4 feet bgs.
Groundwater was not encountered in any of the SWMU B-13 soil borings; therefore, no groundwater samples were collected
Five anomalies were observed during the geophysical survey activities on March 12 and April 3, 1996 (Figure B13-4). The in-phase data recorded during the EM survey ranged from -10 to 35 ppt (Figure B13-5). Quadrature-phase readings ranged from a low of –80 milliSiemens per meter (mS/m), to a high of 35 mS/m (Figure B13-6). Three of these anomalies are thought to be potentially associated with subsurface waste management practices. Two other anomalies were identified as being associated with surficial construction debris.
In accordance with the approved work plan, soil gas survey samples were not collected in association with the current investigation conducted for SWMU B-13.
Surface soil sample results are presented in Section 2.2.4, with the boring from which they were collected.
As shown in Table B13-1, several compounds exceeded RRS1 criteria in surface and subsurface soil at SWMU B-13. Concentrations of bis(2-ethylhexyl)phthalate detected in subsurface samples are considered to be associated with laboratory contamination. Surface soil exceedances of chromium, copper, nickel, lead, and zinc are presumed to be associated with waste management activities at the site.
2.2.5 Groundwater SamplesMetals
Chromium, copper, lead, nickel, and/or zinc concentrations in four surface soil samples exceed RRS1 criteria. Copper concentrations in surface soil exceed RRS1 soil/rock criteria in RW-B13-SB01 (185.4 mg/kg), RW-B13-SB02 (68.6 mg/kg), and RW-B13-SB04 (124.8 mg/kg). The field duplicate for RW-B13-SB01 also had a copper detection of 42.5 mg/kg. The RRS1 background level for copper in soils is 23.2 mg/kg.
Lead concentrations present in two surface soil samples collected from the Krum Complex soil (surficial soils) exceed RRS1 soil/rock criteria. Concentrations of lead exceed RRS1 values in surface soil at RW-B13-SB02 (197.6 mg/kg) and RW-B13-SB04 (127.2 mg/kg). The RRS1 background level for lead in soils is 84.5 mg/kg.
Zinc concentrations in RW-B13-SB02 (161.2 mg/kg) and RW-B13-SB04 (164.4 mg/kg) exceed the RRS1 background level for soils of 73.2 mg/kg. At RW-B13-SB04, chromium was detected at 66.7 mg/kg, exceeding the background level in soils of 40.2 mg/kg. Also in RW-B13-SB04, nickel was detected at 60.4 mg/kg, above the background level of 35.5 mg/kg.
Metals were not detected above RRS1 criteria in any of the subsurface samples consisting of Glen Rose Limestone material.
VOCs and SVOCs
One VOC (1,2-dichlorobenzene) and one SVOC (bis(2-ethylhexyl)phthalate) were detected above RLs. A 1,2-dichlorobenzene concentration of 0.0101 mg/kg in RW-B13-SB04 (9.5 to 10) exceeds the RL of 0.002 mg/kg.
Bis(2-ethylhexyl)phthalate (or DEHP) was detected above RLs in nine soil/rock samples. The soil samples that these detections occurred in are; RW-B13-SB01 (6.5-7.0), (11.5-12.0); RW-B13-SB02 (0.5-1.0 and its field duplicate), (6.5-7.0) and (10.0-10.5); RW-B13-SB03 (4.0-4.5) and (8.5-9.0), and RW-B13-SB04 (3.5-4.0). DEHP concentrations ranged from 3.5 mg/kg in soil boring RW-B13-SB02 (6.5-7.0) to 15 mg/kg in soil boring RW-B13-SB03 (4.0-4.5).
Fluoranthene was detected above RRS1 in one subsurface soil sample, RW-B13-SB01 (0.5-1.0) FD1. The soil concentration of fluoranthene was 0.71 mg/kg and the RL is 0.7 mg/kg. However, the concentration detected in the parent sample (RW-B13-SB01) (0.5-.1.0) was below the RL.
As shown in Table B13-1, several other VOCs and SVOCs were detected at concentrations below RRS1 criteria in SWMU B-13 samples. At RW-B13-SB01 (0.5-1 feet), several polycyclic aromatic hydrocarbons were detected at concentrations below RLs. Other compounds detected at very low concentrations included methylene, chloride, bromobenzene, pentachlorophenol, toluene, and 1,4-DCB.
As described in Section 2.1.5, groundwater samples were not collected during the current investigation conducted for SWMU B-13.