|
LLM�A
<br /> RMa, , TMh
<br /> 'oOw sco <: ,uDuM,°a p ';Kau p,d
<br /> where debris was buried (F'igmc 41. None of the trenches ate visible in air photo taken in 1976,
<br /> indicating that use of the (reaches bad been discontinued. Rand on the air photo interpretations
<br /> and employee interviews, the debris burial benches consisted of a series or 2 to 3 trenches
<br /> thought to range in six fmm 150 R long by 20 n wide to 30 R long by 10 ft wide. The
<br /> r tre m depth of these trenches was approximately 10 R. Arrive apor induced and passive
<br /> sell vapor surveys were conducted in the area to identify areas of elevated VOCs in soil vapor.
<br /> In addition, magnetic and GPR surreys were conducted in the vicinity of the debris burial
<br /> trenches to identify areas where metal containers or drums, and Iran containingdebris might be
<br /> burned, as well as to help determine the exact locations and sizes of the debris burial trenches.
<br /> Based on the results of Ole air photo interpretations, cnployee interviews, and vapor surveys,
<br /> and magnetidGPR surveys, six test pits were excavated within the Yastem GSA debris burial
<br /> trenches in 1990 to verify the nature of the debris placed in the trenches, and to collect mil
<br /> samples to determine nature and extent of contamination in the debris burial ranch area
<br /> (Figure 5). As shown on Figure 51 the test pits were located to Correspond Ish vertical magnetic
<br /> gradient anomalies. It seas verified that the trenches contained craft shop debris, such as scrap
<br /> metal, lathe lumings, porcelain shards, electrical wire, assorted metal pipes, and glass (Figure 6).
<br /> Crag shop debris was encountered in Five fthe six test pits. fins material had been mixed with
<br /> sail during placement. The results of the magnetidGpR surveys, which indicated that drums or
<br /> metal etal container were not present in the trrnewsp was confirmed by the test pit excavations.
<br /> Sail samples collected fmm the just pits were analyzed for VOCs. The VOC analytical
<br /> results br these soil samples indicated the presence of very law concentrations
<br /> of 'ICE
<br /> (0.0009mllligrams per kilogram ImglkgD, tmmchlommhrne (PCE) (0.0013
<br /> 1,1,2,2-tetmchlomethane (PCA) (O.On02 mg/kg), dichlorobnmene (0.0002-0.0003mgkg)),
<br /> chlomform (0.0005 mg/kg), and Freon 113 (0.0002 mg/kg) in one of the test pits. No other
<br /> VOCs were detected above the rcpnrting limit in any of the other test pit mil samples, with the
<br /> exception of TICE usua d at the 0.0001 mg/kg reporting limit in used sample been test pit as,
<br /> Although craft shop debris was also encountered in three of the other test pits, no VOCs were
<br /> detected above the O.00o1 mghg minoring limit in samples from these pits. No debris was
<br /> encountered and no VO kg('s were detected above the O.Mill mg reporting limit in the sample
<br /> fmmthe .sixth test pit. The concentrations of TCE, PCE, 1,1,2,2-PCA, dichlombenzene,
<br /> chloroform, said Freon 113 detected in mil samples fmm the test pits ate all well below the most
<br /> recent (June 2015) EPA industrial and residential soil RSLs and the MCL pmtw0on of ground
<br /> MIer mil screening levels.
<br /> As No of the remedial investigation of the Eastern GSA, IR)E,LI.NL also collected and
<br /> analyzed samples of surf ce .mil and subsurface used form borchnles for VOCs and metals,
<br /> including samples been within the debris burial trenches. Within the Eastern GSA debris burial
<br /> launch area, 52 soil samples were colleetel from the vadose zone (0 to 30 d head in seven
<br /> borcholes. All VOC mil detections were below both the residential and industrial soil RSLs
<br /> (Juno 2015) that incorporate the recently revised TCB toxicity aloe. OTiny-nine onshe and
<br /> oRhite monitor wells were also installed in due Eastern GSA he characterize the vertical and
<br /> horizontal extent of ground water contamirmlimn and m determine ground water Raw direction
<br /> and gradient.
<br /> A Site-Wide Remedial Investigation (SWRI) report that summational e the results of
<br /> characterization of Site 300, including the GSA OU, sea sued I, l994. The remedial
<br /> mvestigation concluded that the debris in [be burial launches, which was contaminated with small
<br />
|