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Interim Investigation Report June 21, 1996 Chapin Brothers Automotive Stockton, California i i A-1.0 FIELD METHODS FOR SOIL BORINGS Soil borings LB through L133 were drilled using a Mobile B-81 drilling rig equipped with 8 and ' 10 in-diameter, continuous-flight, hollow-stem augers operated by V and W Drilling of Rio Vista The auger flights were steam-cleaned prior to use in each boring to minimize the possibility of downhole or ' cross-boring contamination Samples were described using the Unified Soil Classification System (Figure B-1), descriptions of the materials encountered are presented on Logs of Bonngs in Appendix B (Figures B-2 through B-4) 1,131, LB2, and L133 were drilled to total depths of approximately 25-30 ft and converted into VE-5, VE-6, and MWS, respectively I ' During drilling, soil samples were collected at 5-ft intervals using a California-modified, split- spoon sampler equipped with clean brass sleeves The number of blows required to drive the sampler each successive 6-in interval was counted and recorded to give an indication of soil consistency Samples were collected by advancing the boring to a point immediately above the sampling depth, then driving the sampler into the native soil through the hollow center of the auger The sampler was driven 18 ins with a standard 140-1b hammer dropped 30 ins Soil samples from each interval were sealed with aluminum foil, plastic end caps, and duct tape The samples were labeled and placed in iced storage prior to pickup by the analytical laboratory Soil samples were selected for chemical analysis from each boring based on the previously submitted Workplan, on previous laboratory analyses, and on the depth that groundwater was encountered A Chain ' of Custody Record was initiated by the field geologist and accompanied the samples to the laboratory A copy of this record is presented in Appendix C Drill cuttings were placed on plastic and covered with plastic The soil was left at the site pending the results of analyses Disposal of the soil remains the responsibility of the client Lush Geoscicnces can ' arrange to have the soil removed to an appropriate disposal facility or for treatment of the soil to reduce the contaminant levels with the authorization of the client L USH GEOSCIENCES