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N&MAutomotive August 31 2000 11 Field Methods Exploratory Borings One exploratory boring was drilled at the site (Figure 1) on July 27, 2000 The boring was positioned to ascertain distribution of the contaminants in site soil and groundwater at the former location of Well MW-1 Drilling permits were secured from the PHS-EHD, and all utilities were cleared prior to doing the fieldwork The borehole was drilled with truck mounted direct push drilling equipment All drilling equipment and sampling tools were cleaned prior to arriving, between driving samples and before leaving the site The drill string was advanced to the desired sampling depth interval, and a drive split spoon sampler was driven into undisturbed soil The sampler was then retrieved and dissembled, the soil filled acetate liners retained for chemical analysis, sealed with Teflon® paper or foil and plastic end caps, labeled, logged onto chain-of-custody forms and place in a chilled ice chest on crushed ace Drill cuttings were drummed and left on-site • The borehole was logged using the Unified Soil Classification System under the supervision of a registered geologist Additional lithologic information was collected to describe the subsurface geology Soil samples were field screened for presence of contaminants by checking for presence of odor and staining, and a photo ionization meter was used for reconnaissance soil field vapor measurement use Soil samples were collected at minimum five-foot intervals, with additional samples collected at intervals of obvious contamination and at stratigraphic features of interest using field discretion A PHS-EHD representative observed the fieldwork Upon completion of the borehole drilling and collection of information, the borehole was backfilled with grout, placed from the bottom to top of the borehole with a tremae lane Field Modification of Work plan The PHS-EHD representative and field geologist discussed the sampling as the borehole drilling and sampling progressed on July 27, 2000 Field observations indicated that contaminants were present but appeared to decrease with depth, so PHS-EHD in the field approved the following modification to the fieldwork and sampling The boring was advanced to a depth of 32 feet Groundwater samples were collected Just into the aquifer (about 16 to 20 feet) and a second groundwater sample was collected at the base of the borehole (about 28 to 32 feet) This lower sample was collected since the RWQCB had used similar sampling approach to observe for decreasing contaminant levels as a possible criterion for site closure Page 2 SO/mso/cusum&m