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SWMU B-30 RCRA Facility Investigation Report
Section 2 - Field Investigation
As outlined in the Environmental Encyclopedia site-specific work plan (Volume 1-2, SWMU B-30), the objectives of the site assessment were to conduct a geophysical survey and collect surface and subsurface soil samples at SWMU B-30, 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 in the CSSA Environmental Encyclopedia (Volume 1-4, Field Sampling Plan). A summary of analytical results is provided in Appendix A.
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 location and analytical data will be incorporated into the CSSA GIS.
An EM geophysical survey was conducted at SWMU B-30 in April 1996. Prior to collecting EM data, a grid system was established at the site which encompassed the areas of suspected ground disturbance. This grid 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. Figure B30-4 illustrates the layout of the geophysical survey grid which measured 200 feet by 250 feet and covered 1.1 acres in area. The northeast corner of the grid was not surveyed because this area is a 7 to 8 feet tall limestone embankment resulting from past quarrying activities.
EM data were collected at 2-foot intervals along transects that were separated by 10 to 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 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 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.
Soil gas samples were not collected at SWMU B-30 as part of the current investigation.
Three surface soil samples were collected at SWMU B-30 on March 12, 1996 for VOCs, SVOCs, and metals analyses. The sampling locations were situated in areas identified as having the greatest potential for contamination. Surface sample number B30-SS03 was the most eastern of the three samples, collected near a pile of shingles, just south of a mapped geophysical anomaly. Sample number B30-SS02 was collected just south of a large construction debris/rubble pile present in the central portion of the site area. Sample number B30-SS01 was collected next to a pile of concrete slabs, near the limestone embankment that lies in the northern portion of the site area (Figure B30-4).
All soil samples collected during 1996 were submitted to ITS Laboratories. In 1998 it was learned that these sample results were invalid and would not be accepted by EPA for closure purposes. Therefore, in March 2000 samples were collected adjacent to the 1996 sampling locations as part of a rework effort. In addition, a surface soil sample was collected at RW-B30-SB01, adjacent to geophysical anomaly B.
Samples collected at SWMU B-30 as part of the rework were submitted to two laboratories. VOC and SVOC samples were analyzed by APPL, Inc. in Fresno, California using EPA methods SW-8260B and SW8270C, respectively. Metal analyses included barium, chromium, copper, nickel, and zinc (SW-6010B); arsenic (SW-7060A); cadmium (SW-7131A); lead (SW-7421); and mercury (SW-7471A), all conducted by O’Brien & Gere Laboratories in Syracuse, New York.
On August 29, 1996, three soil borings (B30-SB01, B30-SB02, and B30-SB03) were advanced at SWMU B-30 and samples were submitted to ITS Laboratories. Borings were located near surface rubble, construction debris piles, and/or subsurface geophysical anomalies identified within the site area. In 1998, EPA determined that data from ITS Laboratories would not be acceptable for site closure purposes.
In March 2000, rework boring RW-B30-SB02 was advanced at the same location that surface soil sample RW-B30-SS02 was collected. Boring RW-B30-SB01 and RW-B30-SB03 were advanced near surface soil samples RW-B30-SS01 and RW-B30-SS03, respectively (Figure B30-4).
A total of seven samples were collected from the three borings. RW-B30-SB01 was sampled from three intervals: 0.5-1.0, 4.5-5.0, and 12.5-13.0 feet bgs. Boring numbers RW-B30-SB03 and RW-B30-SB02 were sampled at two intervals. RW-B30-SB02 was sampled from 3.5-4.0 feet bgs and 7.0-7.5 feet bgs, and RW-B30-SB03 was sampled from 2.5-3.0 feet bgs and 9.0-9.5 feet bgs.
Samples collected at SWMU B-30 in March 2000 were submitted to two laboratories. VOC and SVOC samples were analyzed by APPL using methods SW8260B and SW-8270C, respectively. Metals samples were analyzed by O’Brien & Gere Laboratories, using method SW6010B for barium, chromium, copper, nickel, and zinc; SW7060A for arsenic, SW-7131A for cadmium, SW-7421 for lead and SW-7471A for mercury. A total of 17 samples were collected and submitted for laboratory analysis. These samples included four surface soil samples, two surface soil field duplicates, one surface soil matrix spike (MS), one surface soil matrix spike duplicate (MSD), six subsurface soil samples, one soil boring field duplicate, one soil boring MS, and one soil boring MSD.
In accordance with the approved work plan, groundwater samples were not collected during this investigation for SWMU B-30. Groundwater was not encountered in any of the borings.
2.2 - Results and Comparisions
Both in-phase and quadrature-phase EM data identified two anomalies at the site. Figure B30-5 and Figure B30-6 show the results and locations of EM data collected at SWMU B-30.
Two anomalies, labeled A and B, are shown by the in-phase EM data (Figure B30-5). Anomaly A, located in the northwestern portion of the site, is an area where readings as high as 11 ppt were observed. Due to its location, it is interpreted as being associated with a pile of concrete slabs (probably steel-reinforced) at the same location. This anomaly is also visible in the quadrature-phase data.
Anomaly B is located in the northeastern portion of the site, adjacent to the northern limestone embankment. The contour gradient is not as great as it is at anomaly A; however, it is visible in both in-phase and quadrature-phase data. Since surface waste was not observed at this location, this anomaly may be associated with buried waste.
In accordance with the approved work plan, soil gas samples were not collected during this investigation for SWMU B-30.
Concentrations slightly above background were detected in one surface soil sample, RW-B30-SS3. Results are summarized in Table B30-1, and complete results are provided in Appendix A.
All samples contained VOC and SVOC concentrations at or below RLs. Therefore RRS1 criteria for VOCs and SVOCs have been met. The following compounds were reported for the surface soil samples at concentrations below the laboratory RLs: benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(g,h,i)perylene, bis(2-ethylhexyl)phthalate, chrysene, fluoranthene, indeno(1,2,3-cd)pyrene, methylene chloride, naphthalene, phenanthrene, pyrene, toluene, and 1,2,3-trichlorobenzene.
One of the three surface soil samples (RW-B30-SS03) had reported constituent concentrations exceeding RRS1 standards. Analytical results for sample number RW-B30-SS03 reported 47.3 mg/kg copper, 86.46 mg/kg lead, and 93.2 mg/kg zinc. The RRS1 standards for copper, lead, and zinc CSSA soils are 23.2 mg/kg, 84.5 mg/kg, and 73.2 mg/kg, respectively. Sample RW-B30-SS03 was collected near a pile of discarded roofing shingles.
Copper was detected in surface soil sample RW-B30-SS03 at a concentration of 47.3 mg/kg which exceeds the background level (23.2 mg/kg). The most stringent TRRP Tier 1 PCL for copper is the TotSoilComb PCL of 550 mg/kg and the detected concentration is well below this applicable TRRP PCL for copper. Lead was detected at a concentration of 86.46 mg/kg in surface soil sample RW-B30-SS03, which is only slightly higher than the calculated background level of 84.5 mg/kg for CSSA soils. The applicable TRRP Tier 1 PCL for lead is the TotSoilComb PCL which is 500 mg/kg. The detected concentration for lead (86.46 mg/kg) is well below this PCL.
Metals slightly exceeded background levels in three subsurface samples, and common laboratory contaminants methylene chloride and bis(2-ethylhexyl)phthalate exceeded RLs in five samples. Results are summarized in Table B30-2, and complete results are provided in Appendix A.
One VOC, methylene chloride, was detected slightly above its corresponding RRS1 standard within sample RW-B30-SB03 (2.5-3.0 feet bgs). This sample had a reported methylene chloride concentration of 0.0072 mg/kg. The laboratory RL for methylene chloride, a common laboratory contaminant not known to be disposed at the site, is 0.005 mg/kg. Naphthalene was reported at concentrations below the laboratory RLs in two samples (Table B30-2). Summary analytical results are provided in Appendix A and Soil Boring Logs are provided in Appendix B.
Only one SVOC, bis(2-ethylhexyl)phthalate, exceeded RRS1 criteria and it was reported within five of the seven samples that were tested. Sample numbers RW-B30-SB01 (12.5-13.0 feet bgs), RW-B30-SB02 (3.5-4.0 feet bgs), RW-B30-SB02 (7.0-7.5 feet bgs), RW-B30-SB03 (2.5-3.0 feet bgs), and RW-B30-SB03 (9.0-9.5 feet bgs) had reported bis(2-ethylhexyl)phthalate concentrations of between 6.8 mg/kg and 26 mg/kg. The laboratory RL for bis(2-ethylhexyl)phthalate is 0.7 mg/kg.
For two of the three borings, three metals were detected at concentrations slightly exceeding RRS1 standards in samples collected from the Glen Rose Limestone Formation. Sample number RW-B30-SB01 (12.5-13.0 feet bgs) had reported concentrations of barium and cadmium at 11.1 mg/kg and 0.13 mg/kg, respectively. The RRS1 standards for barium and cadmium in Glen Rose Limestone material are 10.0 mg/kg and 0.1 mg/kg, respectively. Sample number RW-B30-SB03 (2.5-3.0) had a reported nickel concentration of 7.9 mg/kg, slightly higher than the RRS1 standard of 6.8 mg/kg for Glen Rose Limestone.
Under TRRP, the protective concentration level (PCL) for Tier 1 residential sites with a 0.5 acre source area [30 TAC §350.75(b)(1)] should be the most stringent of two applicable PCLs. These will be either the combined soil PCL (TotSoilComb) or the groundwater protective soil PCL (GWSoilIng), depending on the constituent being compared. For the three metals exceeding RRS1 criteria (barium, cadmium, and nickel), the most stringent of the two PCLs is the GWSoilIng PCL and none of the metals concentrations exceed these Tier 1 PCLs.
The extent of metals contamination in soils at concentrations warranting concern at SWMU-B30 have been defined. Although these concentrations exceed RRS1, the values do not exceed TRRP Tier 1 applicable soil PCLs when compared to the most stringent, applicable TRRP PCLs.
In accordance with the approved work plan, groundwater samples were not analyzed during this investigation for SWMU B-30. Groundwater was not encountered in any of the soil borings.