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Geo(ngicaCTedwics Inc. Page 4 Hunter Container Report-Soil and Groundwater Investigation Project No. 397.2 October 25, 1996 Recommendations Geological Technics Inc. recommends that San Joaquin County and RWQCB work with the two pipeline companies to address the petroleum hydrocarbon issue. I The TCE is present at such a low concentration as to cause no significant environmental concerns and so Hunter Container should not be required to assess this any further and that the site be closed. i 1.0 SOIL & GROUNDWATER INVESTIGATION i To further investigate the lateral and vertical extent of soil impacted with volatile organic compounds, Geological Technics Inc. drilled four soil borings surrounding the point of release. One boring was converted into a groundwater monitoring well (Figure 2 Site Map). 1.1 Soil Borings Prior to commencing work a soil boring/monitoring well permits was secured and the SJCPHSEHD was notified 48 hours in advance. The borings were drilled using a 8.00 inch outside diameter continuous flight hollow stem auger owned and operated by V&W Drilling 1 (C579 720904). The subsurface was cleared of underground utilities by notifying Underground Service Alert. The soil borings were extended to the capillary fringe. The depth to groundwater in this area is 30 feet below grade. SB-1 was drilled using continuous coring methods for the purpose of evaluating the subsurface geologic condition. This core was kept for future references. The boreholes were closed by pumping a neat cement grout containing <4% bentonite to grade, using a grout pump and tremie pipe. Clean soil cutting were stockpiled and obviously contaminated soil cuttings may be underlain and covered with plastic and segregated from the clean stockpile or containerized in DOT approved 55 gallon steel drums. 1.2 Soil Sampling Procedure During drilling, soil samples were collected for geological and analytical evaluation at five feet intervals. A boring log providing sediment description using the USCS and field observations was maintained by Tim McDonald, geologist for GTI, working under the supervision of Ray Kablanow, a California Registered Geologist and Certified Hydrogeologist. Boring logs are attached in Appendix A. Soil samples were collected in 6.0 inch brass liners using a 2.0 inch modified California split spoon sampler. All soil samples were sealed with aluminum foil or Teflon sheets, capped, labeled and placed in a cooler at 4° Celsius for transport to the laboratory following Chain of Custody protocol. Because every soil sample collected will not be submitted for laboratory analysis, a screening process was used to gather additional information through field observation noting sediment type, especially grain size and clay content; moisture content; visible evidence of contamination, i.e., color change due to reduction of iron or discoloration from hydrocarbons and other pollutants, and the readings above background on a organic vapor meter (OVM).