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CAMBRIA Methyl tertiary butyl ether (MTBE) was reported (by EPA Method 8020) in a soil sample collected from the western portion of the former UST excavation at a depth of 19 fbg The MTBE concentration in this sample was reported at 1,800 ppm TPPH and benzene, toluene, ethylbenzene, and xylenes (BTEX) concentrations were below or near detection limits in the soil samples collected from the former UST excavation These data are documented in the Enviros, Inc Underground Storage Tank Removal Report dated June 20, 1996 Additional investigation performed during October 1997 included drilling two soil borings (SB-1 and SB-2) with Geoprobe equipment to determine the vertical extent of petroleum hydrocarbons and MTBE previously identified during tank removal activities Soil boring SB-1 delineated the vertical extent of the petroleum hydrocarbons and MTBE in the western portion of the former tank complex Soil boring SB-2 was drilled to the depth of 35 5 fbg where drilling refusal was encountered The final soil sample collected at 35 5 fbg contained TPPH at a concentration of 5,700 ppm and did not contain detectable levels of MTBE (by EPA Method 8260) and benzene These data are documented in Cambria's December 1, 1997 Site Investigation Report • During April 1998, one soil boring (SB-3) was drill at the location of boring SB-2, to further delineate the vertical extent of petroleum hydrocarbons in soil This boring was drilled with a limited access drilling rig to 55 fbg where drilling refusal was encountered TPPH was detected in a soil sample collected at 50 fbg from this boring Groundwater was encountered in this boring at approximately 52 fbg Since petroleum hydrocarbons were present in soil immediately above groundwater, three groundwater monitoring wells (S-1, S-2, and S-3) were installed at the site (Figure 2) These data are documented in Cambria's June 29, 1998 Site Investigation Report Wells S-1, S-2, and S-3 have been monitored and sampled quarterly since they were installed Groundwater flow direction has been predominantly to the south and southeast Groundwater samples from downgradient wells S-2 and S-3 have not contained petroleum hydrocarbons and MTBE, except for low levels of BTEX detected during the fourth quarter of 1998 Well S-1 contained 0 01 foot of separate-phase hydrocarbon during its first groundwater sampling event Since then it has contained TPPH concentrations as high as 200,000 parts per billion (ppb), benzene concentrations up to 5,300 ppb, and has not contained detectable concentrations of MTBE . The results of the current investigation are presented below 0797 2