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At the request of the PHS/EHD, three soil samples collected from the bottom of each boring were submitted to GTEL Environmental Laboratories, Inc in Wichita, Kansas, for analysis of total organic carbon (TOC) by Method CFA 18 0 (California Fertilizer Association, Soil Testing Procedures for California, CFA-SIC Publication, 1980) In addition, three soil samples were submitted to Remediation Technology Testing Facility for geotechnical soil properties by EPA ' Method 415 1, for the following parameters air permeability, total porosity, coarse grain size analysis, bulk density, and moisture content Analytical reports are included in Appendix C 4.0 DISCUSSION FOR CLOSURE The facility at the site has been operating as a gasoline station since 1969 In September 1991, the underground storage tanks (USTs) and associated piping were removed from the site as part of a facility upgrade Laboratory analytical results of soil samples collected during the tank removal activities reported detectable concentrations of TPHg, BTEX, and ethylene dibromide (EDB) Analytical results of soil samples collected during the tank removal are presented in Table 3 ' Based on these results, an assessment was conducted at the site in August 1992 which included a soil gas survey, drilling and soil sampling of seven soil borings, and converting four of the bonngs into groundwater monitor/extraction wells and three of the borings into soil vapor extraction wells ' A soil vapor extraction pilot test was subsequently performed on the vapor extraction wells A copy of the tank pull report prepared by Canome Environmental (Canonise) was forwarded to the office of PHS/EHD on December 17, 1991 A copy of the site assessment report prepared by Canome was forwarded on May 26, 1993 Based on the PHS/EHD's June 24, 1993 reply, an additional investigation was implemented by Science & Engineering Analysis Corporation (SEACOR) in December 1993 Site activities included the advancement of four verification borings to define the ' limit of hydrocarbon impacted soils and re-sampling the groundwater monitor wells A Problem Assessment Report was prepared by SECOR on May 31, 1994 ' On August 26, 1994, a Final Remedial Plan (FRP) prepared by SECOR was submitted to the PHS/EHD for public notification and regulatory approval Before the FRP could be implemented, the State Water Resources Control Board, prompted by a study conducted by Lawrence Livermore ' National Laboratory, issued a statement suggesting that intrinsic bioremediation should be considered an acceptable remedial option in "low risk" cases Based on this information and discussions with the PHS/EHD, Time Oil Company authorized SECOR to present the results of the recent subsurface investigation, verifying that petroleum hydrocarbons in soil at the site are degrading by natural processes IThe four groundwater monitor wells at the site have been gauged and sampled rune times since November 5, 1992 Historical ground water level measurements are presented in Table 4 Over this period, depth to ground water at the site has ranged from 12 92 (W-5, May 1995) to 17 42 (W-6, ' July 1994) The analytical results for ground water samples in monitor wells W-3, W-5, W-6, and W-7, have consistently been below the method detection limit for TPHg and benzene (since the wells were installed) The only historical ground water samples reported with petroleum SECOR 14341NV RPT J0710-002-01 3 Oc[a6cr 9 1996 1