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2.0 SOIL BORINGS ' 2 1 Introduction ' In May 1998, Remedy supervised the drilling of two deep soil bonngs to help define site lithology and hydrogeology An initial attempt was made to obtain continuous core samples using mud rotary drilling (samples were to be collected in 5 foot acrylic sections to a final depth of 145 feet) ' However, the driller was not able to get consistent recovery in the sample tubes and drilling was discontinued A decision was then made to use Cone Pentrometry to obtain the continuous core data Gregg Drilling, Inc was selected to complete the two deep bonngs This work is described in detail in the following sections Copies of the drilling permits are presented in Appendix B 2.2 Mud Rotary Auger Drilling by WESTEX (Boring B-11) IOn May 12, 1998 Westex began mud rotary drilling near the former waste oil tank location (B-11) for the collection of continuous core soil samples The mud rotary sampler was to collect soil samples in 2 5 inch diameter acrylic tubes Each tube was 5 feet in length However, very little soil was recovered in the sampler(usually only a 6 to 8 inches of soil recovered for every 5 foot length of sample) The problem was thought to be due to the cutting shoe, which was not correctly matched to the diameter of the sampling tubes The drilling was stopped at 16 5 feet so that the driller could get a cutting shoe that was correctly matched to the sample tube wall thickness In addition, a the driller also wanted to try thin wall sample tubes if the cutting shoe retrofit did not work Because of a delay in getting the new cutting shoe and thin wall sample tubes, drilling continued late in the morning on May 13, 1998 The new cutting shoe was used as drilling continued beyond 16 5 feet below grade surface Fairly good sample recovery was obtained to a depth of 34 feet However, the system failed below 34 feet depth As a result, drilling was stopped and the borehole was gouted to the surface Following the drilling it was found that bentonite had sealed the sample lock device, so that collected samples would not stay in the sample tube Soil samples collected at depths of 14 feet and 33 feet below grade were submitted for chemical analysis The results of sampling are summarized in Tables 8 and 12 Hydrocarbon contamination was reported for the sample at 14 feet below grade The sample collected at 33 feet depth was"non- detect" for the parameters tested Soil lithology for boring B-11 was logged by Don Kubik, Remedy, Inc A copy of the boring log is presented in Appendix G 2.3 Cone Pentrometry Testing by Gregg Drilling (CPT-11 and CPT-12) Because we were unable to collect continuous core samples using the mud rotary process, a decision was made to use cone penetrometry to obtain soil lithology data and also to obtain discrete samples at varied depths for chemical analysis Gregg In Situ, Inc of Gregg Drilling,Martinez, California was selected to complete the cone penetrometry testing (CPT) at the site On May 27 and 28, 1998, they Remedy Inc Interim Investigation and Remediation Report September 16 1998 Frank's One Stop, 2072 W Yosemite Avenue Manteca, C4 01511R RPT 4