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CAMBRIA 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 SBA 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 TPHg at a concentration of 5,700 ppm and did not contain detectable levels of benzene and MTBE These data are documented in Cambria's December 1, 1997 Site Investigation Report During April 1998, one soil boring (SB-3) was drilled at the location of boring SB-2, to further delineate the vertical extent of petroleum hydrocarbons and MTBE in soil This boring was drilled with a limited access drilling rig to 55 fbg where drilling refusal was encountered TPHg 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 These data are documented in . Cambria's .lune 29, 1998 Site Investigation Report During December 1999 one well (S-4) was installed and three cone penetrometer testing (CPT) borings (SB-4, SB-5, and SB-6) were drilled at the site Well S-4 was installed downgradient of S-1, and in the center of the site SB-4 was drilled adjacent to S-1 to assess the vertical extent of hydrocarbons in soil and groundwater near the suspected source area Borings SB-5 and SB-6 were drilled to assess the lateral extent of impacted soil Soil samples below 30 fbg did not contain petroleum hydrocarbons or MTBE with the exception of a few low level detections of TPHg and benzene Groundwater samples collected from boring SB-4 at 60, 72, 82, & 95 fbg contained TPHg ranging from 90 3 to 22,700 ppb, and benzene ranging from 1 0 to 3,150 ppb No MTBE was detected in these groundwater samples These data are documented in Cambria's April 14, 2000 Site Investigation Report Wells S-1, S-2, S-3, and S-4 have been monitored and sampled quarterly since they were installed Groundwater flow direction has been predominantly to the south and southeast Groundwater samples from wells S-2, S-3, and S-4 have consistently not contained petroleum hydrocarbons and MTBE, except for a few low level detections Well S-1 has contained TPHg concentrations as high as 392,000 parts per billion (ppb), benzene concentrations up to 5,300 ppb, and has not contained detectable concentrations of MTBE 0797 3