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' Appendix A - Site Summary ry ' AGE-NC Project 95-0130 Page 2 of 5 4 0. PREVIOUS SUBSURFACE INVESTIGATION The following is a summary of previous investigations at the site of the unauthorized release of fuel products to the subsurface • December 1994 - Five soil borings (13-1 through B-5) were advanced at the site near the former UST areas to depths of 65 feet below surface grade (bsg) Petroleum hydrocarbon- impacted soil was encountered in all five soil borings at depths between 10 and 65 feet bsg ' Results of the December 1994 investigation were reported in Preliminary Investigation and Evaluation Report(PIER),dated 10 April 1995,prepared by Geological Audit Services,Inc • January 1995 - Three ground water monitoring wells (MW-1, MW-2 and MW-3) and one soil boring (13-6) were advanced at the site as part of site assessment activities Soil boring B-6 was advanced to a depth of 65 feet bsg, wells MW-1, MW-2 and MW-3 were advanced to depths of 80 feet bsg Petroleum-impacted soil was encountered in all four boring Ilocations at depths between 35 feet and 65 feet Dissolved TPH-g and BTEX compounds were detected in initial ground water samples from all three wells at concentrations up to 11,000 micrograms per liter (µg/l) Results of the December 1994 investigation were reported in Preliminary Investigation and Evaluation Report (PIER) dated 10 April 1995, prepared by Geological Audit Services, Inc ' December 1995 - Three soil vapor extraction (SVE) wells (VW-1, VW-2 and VW-3) were advanced to depths of 63 feet bsg near the former UST areas, one ground water monitoring well (MW-4) was advanced to a depth of 75 feet bsg and located in the warehouse building structure, approximately 60 feet southeast of the former UST area TPH-g and BTEX- impacted soil was encountered in all three SVE wells at depths between 15 feet and 60 feet at concentrations as high as 7,400 mg/kg, petroleum hydrocarbons were not detected in soil tsamples collected from MW-4 Dissolved TPH-g was not detected in initial ground water samples collected from MW-4 Results of the December 1995 investigation were reported ' in Corrective Action Plan (CAP), dated 20 March 1996, prepared by AGE • January 1996 - One ground water monitoring well (MW 5) was advanced off-site, approximately 50 feet northwest of the former UST area to a depth of 70 feet TPH-g and ' BTEX-impacted soil was encountered at depths of 45 and 50 feet at concentrations as high as 940 mg/kg TPH-g and BTEX-impacted ground water was detected in the initial sample from.MW-5 at a concentration of 23,000µg/1 Results of the January 1996 investigation were ' reported in the CAP An 8-hour SVE pilot test was conducted at the site by inducing a vacuum from well V W-1 B (screened 28 to 43 feet bsg) The pilot test was performed to provide vapor extraction data for proper system design of an SVE remediation system TPH-g and BTEX compounds were detected from influent SVE air flow samples at concentrations as high as 95,000 micrograms Advanced GeoEnvironmental,Inc