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1995 Technical Memorandum on Soil Boring Investigation
Section 7 - SWMU Burn Area 19 (B-19)
Miscellaneous solid waste, metal, and weapons were identified as potential wastes at B-19 on CSSA's original list. Three soil borings were drilled at this site, which appeared to have been a "scrape" area for soil (Figure 7.1). Because holding times for VOC analysis were missed, the three soil borings were redrilled (Figure 7.1).
7.1 - Geology and Hydrogeology
No surface soils were observed at the site. As part os site management activities, the soil was scraped from the surface and mounded at the ends of the scrape area or removed from the site.
Highly weathered, marly limestone was logged as interbedded with massive limestone with clay seams. Vugs were present throughout the entire depth of each core. Some appeared to be the result of dissolution of or around zones of fossil hash. In B19-SB1 from 21 to 2.5 ft bgl, solution channels horizontally bisected the core. Bioturbation was seen in B19-SB3 from 26 to 27 ft bgl. At approximately 24 ft bgl, the color changed to gray. The rest of the core was alternating white and shades of yellow with a couple thin intervals of light gray.
The interval from 10 to 15 ft bgl contained foraminifera, pelecypods, and gastropods and was light gray in color. In B19-SB3, this interval was fossiliferous.
Perched groundwater was only encountered in one boring during the initial drilling, indicating the presence was spotty. Water was seen in vugs from 23 to 24 ft bgl in B19-SB3. The perched water was measured at 28.5 ft bgl in boring B19-SB3.
During the redrilling activities, perched groundwater was encountered in the three borings. Water levels were 21.5, 5.10, and 20.12 ft bgl for B-19 soil borings SB1R, SB2R, and SB3R, respectively. Prior to drilling these borings it rained, and surface water was standing in the depressions where the original three borings were drilled. Surface water thus was able to infiltrate the boreholes. The boreholes were not drilled within the depressions, but surface water levels were observed to lower while drilling. Also, small bubbles were seen rising in the surface water during air coring.
7.2 - Observed Waste Material in the Borings
Waste material was not encountered in the boreholes.
7.3 - Soil/Rock Analytical Results
No VOCs were detected in the original samples or redrill samples. Di-n-butylphthalate, a common laboratory contaminants, was detected in the eleven samples collected for SVOC analysis. Lead and nickel were detected in eight of the samples and chromium was detected in three. Cadmium results were qualified as nondetect. The analytical results of the nineteen samples collected are presented in Table B19-1.
7.4 - Groundwater Analytical Results
One water sample was collected from B19-SB3 and analyzed for VOCs as part of the initial drilling (Table B19-2). No VOCs were detected.
Three water samples were collected as part of the redrilling effort and analyzed for VOCs (Table B19-2). Sample B19-SB2R(GW) contained 0.007 mg/l PCE. The remaining two samples did not contain VOCs.
7.5 - Statistical Comparison with Background Metals and Risk-Based Closure Criteria
The concentrations of metals detected did not exceed MSC or statistical background concentrations. There are no comparison criteria for phthalates and therefore none were made.
The concentration of PCE (0.007 mg/kg) detected in B19-SB2R (GW) exceeded the MCL of 0.005 mg/l PCE.