WORK PLANS - Laserfiche WebLink

Home Browse Search

LLNL ,ad07015 Corse our asrsirfor dKEasrem Oct svd,rm0 May 2017 conducted to identify and evaluate activities conducted in the Eastem USA that may have resulted ant releaser. 'these records reviews and employ« interviews indicated that debris in adi in Central GSA craft shops had been headed m four tanehcs in the Eastern GSA during the loans and VG(N. "o better determine the exact location of the debris burial trenches, DOEILLNI. used historical an photo interpretation, soil vapor surveys, and magnesia and ground penetrating mder(GPR) surveys. Air photos taken in the funds aM early 1970s showed one trench and two other possible branches where debris was buried. None of the homeless were visible in air photo taken in 1976, indicating that use of the trenches bad been discontinued. Based on the air photo inerpreations and employee interviews, the debris burial trenches consisted ofa series oft to 3 trenches thought to range in sin Gom 150 f (R) long by 20 ft wide to 30 ft Inng by 10 fl wide(Figum 2.51 in Appendix A). The depth of thew trenches is thought to be 3 to 5 ft. Active vapor induced and passive soil vapor surveys were conducted in the area to identify areas of elevated VOCs in soil vapor. In addition, magnetic and GPR surveys were conducted in the vicinity of the debris burial branches to identify areas where metal containers, drams, or imn- taining debris might be buried, as well as to help determine the exact locations and sizes ofthe debris burial trenches. Based on the results of the air photo interpretations, employee interviews, soil vapor surveys, and magndidGPR surveys, six [cot pits were excavated within the Eastern GSA debris burial Inches in l anon W verify the nature of the debris placed in the trenches, and to collect soil samples to determine nature and extent of contamination in Me debris burial trench area. it was verified that the trenches contained machine shop debris, such as Wrap mesah lathe turnings preordain shards, electrical whe, assorted metal pipes, and glass. Thu material had Icon mixed with soil during placement. No drums, barrels, or other containers were found. The analysis of soil colledd From the test pits indicated very low concentrations of WF tetmchlmcethene (PCE), 1,1 2,2-tdmchlom thmc (PCA), dichlorrbensne, chloroform, and Fre n 113 in samples from som cof[helest pits. 3hese results are discussed in more detail in Appendix A. As pan ofthe amci ial investigation of the Lester GSA Subarea, DOOLLNL also collected and analyzed croupier of surface soil and subsurface soil. Boreholes were drilled, logged, and sampled to characterize the subsurface geology and contamination in subsurface said. Thidy-nine onsite and rffsia monitor wells were installed in the Easter GSA to chameterin the vertical and horizontal extent of grand water on lamination and to determine ground water flow direction and gradient, Other sire cttmacterisntirn methods included surface soil sampling and analyses, soil vapor surveys, hydraulic testing, colloidal bmescope investigations, and geophysical surveys. The maximum concentration of VOCs detected in encountered subsurface so lho& in the Eastern GSA was 0.024 milligrams per kilogram (mglkg) of'I'CE. No VOCs wen ddec[N in surface soil samples above the 0.005 m9Arg reporting limit. VOCswemddectedmgroundwater at above Maximum Confinement Levels (MCLs). A SitoWide Remedial investigation t(SW RI) report that summarised the results afcharacterization of Site 300 including the USA OU was issued in 1994. The remedial investigation concluded that the debris in the burial menthes, which was contaminrated with small quantities of VOCs, was the souaelrelei se site for VOCs deeded in Eastern GSA soil and ground water. "I he results of remedial investigation and baseline risk a esse=ent identified VOCs in ground water as the only contaminants and environmental media of concern in the Gram GSA. WE