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Z4 Borehole Abandonment Upon completion of soil sample collection activities, boreholes were abandoned. The augers were removed and the open boreholes were tremie grouted to grade with a 95% cement, 5% bentonite grout mixture. The top of the boreholes were finished with cement. 2.5 Disposal of Contaminated Materials Dill cuttings from the boreholes, were stored in 55-gallon 17H drums located in the parking lot of the site. Decontamination, development and purge liquids from the on site water well were contained in 55-gallon drums, as they were produced, and stored on-site. Soil samples not selected for analyses were placed into the drums with the drill cuttings to await disposal. Used sample sleeves were disposed of with the drill cuttings. Based on analytical results all stockpiled cuttings were transported to a Class III disposal facility and the water was recycled at an appropriate facihty. 3.0 Result 3.1 Site Geology A review of Versar, Inc. (1988, 1991) and IT Corporation (1993) boring logs indicates that rthe area beneath the former tank location is underlain by sands, and silty sands with silt units encountered between 9.5 and 18.5 feet below grade and 32 to 45 feet below grade, the total ' depth explored IT boring logs can be found in Appendix A of this report. Versar Inc., boring logs can be found in "Site Assessment of the Pacific Bell Ashley Road, Stockton Facility (UE132) - 1989 and Interim Remediation Pilot Study Report _ 1992" by Versar Incorporated. 3.2 Site Hydrogeology Groundwater is known to exist beneath the site at an approximate depth of 135 feet (as witnessed in an onsite water well). Investigative efforts to date have not encountered groundwater, as maximum borehole depths have been 40 feet below grade. Based on topography the suspected groundwater flow direction 1s westerly towards the nearby Calaveras nver. MZ112-08-931ENG/93-1065.nbr 5