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1995 Technical Memorandum on Soil Boring Investigation
Section 3 - SWMU Burn Area 1 (B-1)
Three soil borings were drilled at this former powder and ammunition burn area (Figure 3.1).
3.1 - Geology and Hydrogeology
Logging of soil and rock samples indicated 1 to 4 feet (ft) of dark brown to very dark grayish brown clay with little to some sand overlaying 3 to 7 ft of highly weathered marly limestone. The remaining 19 to 23 ft was massive, hard limestone interbedded with weathered, marly limestone. Vugs of varying size were not uncommon in the more massive, less weathered zones. A fracture was observed in B1-SB2 at 19 ft below ground level (bgl).
Foraminifera and pelecypods of Cretaceous Glen Rose Formation were the predominant fossils identified in the borings. Fossiliferous zones of forams with pelecypods were observed in B1-SB1 from 6 to 11 ft, in B1-SB2 from 13 to 25 ft, and in B1-SB3 from 15 to 20 ft bgl.
Perched groundwater was encountered in B1-SB2 and B1-SB3, but only B1-SB3 produced enough water to sample. The outside of the B1-SB2 core barrel was wet from 20 to 25 ft bgl. The core from this depth was vuggy, but water did not collect in the boring overnight. Moisture was observed on the core barrel of B1-SB3 from 10 to 15 ft bgl. The water level was measured in B1-SB3 at a depth of 12.42 ft bgl.
3.2 - Observed Waste Material in the Borings
No waste material was detected during drilling.
3.3 - Soil/Rock Analytical Results
VOCs were not detected in the ten soil and rock samples collected. Phthalates, common laboratory contaminants, were detected in seven of the samples. Copper and iron were detected in all ten samples. Lead and nickel were detected in five samples and chromium was detected in one sample. Cadmium was qualified as nondetect in all samples for reasons explained above. Analytical results are presented in Table B1-1. Figure 3.2 shows the locations where contaminants of concern were detected.
3.4 - Groundwater Analytical Results
One groundwater and one duplicate sample were collected from B1-SB3. No VOCs or SVOCs were detected in the sample. Chromium and lead were detected in the samples. The results are presented in Table B1-2.
3.5 - Statistical Comparison with Background Metals and Risk-Based Closure Criteria
Chromium exceeded the groundwater protection standard for industrial sites in B1-SB1 (1-4 ft). The location and concentration of the sample are shown in Figure 3.2. The maximum concentrations and the background upper tolerance limits for cadmium, or nickel were not exceeded in the groundwater or soil samples. Lead did not exceed the MSC for soils. Chromium did not exceed MCLs or MSC in the remaining samples.
The concentration of PCE (0.007 mg/kg) detected in B19-SB2R (GW) exceeded the MCL of 0.005 mg/l PCE.