ARCHIVED REPORTS_REPORT OF ADDITIONAL SOIL AND GROUNDWATER INVESTIGATION

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G E.'"7. M A-P.l: • downgradient of the site. On October 12,2000,boring GMX-28 was advanced on site within the ' area of known affected soil and a grab groundwater sample was collected to assess TPH concentrations in groundwater in this area; a previous grab groundwater sample from this area (GMX-12)was only analyzed for BTEX,MTBE and PAHs. Boring locations are shown on Figure 2. ' 4.0 FIELD AND ANALYTICAL METHODS Geomatrix contracted with Precision Sampling,Inc. (Precision),of Richmond,California to advance ' the soil borings during the May and October 2000 investigations. Prior to initiating field activities, Geomatrix obtained a boring permit from the SJCPHS; Cruz Brothers Sub-Surface Locators,Inc.,of ' Milpitas, California,performed an underground utility clearance at each boring location; and Underground Service Alert(USA)was notified. Drilling and soil sampling equipment was steam cleaned prior to use. Soil borings were advanced by Precision using a hydraulically-driven,direct-push drive sampler ' equipped with a 2.5-inch-inside-diameter steel drive casing containing a 1.6-inch-inside-diameter core barrel. A continuous soil core was generated from each boring and logged according to Unified Soil Classification System(USCS)as presented in the American Society of Testing and Materials (ASTM) Standard D2488-90. Boring logs are presented in Appendix B. No petroleum hydrocarbon affected soil was observed in borings GMX-23 or GMX-24. One soil sample was collected from each boring at a depth just above the water table(11 and 12 feet bgs, respectively). Soil samples were collected in clean stainless steel sleeves,sealed with Teflon sheets, plastic end caps,and tape. Soil samples were labeled,sealed in plastic bags,and stored in an ice- cooled chest. Although petroleum hydrocarbon affected soil was encountered in boring GMX-28 between 5.5 and 13.5 feet bgs,no soil sample was collected because this boring was advanced to ' collect a grab groundwater sample only. Grab groundwater samples were collected from all three borings by installing 1-inch-diameter Schedule 40 polyvinyl chloride(PVC)piping in the borehole. The PVC piping consisted of blank casing and a 5-foot-long slotted well screen with 0.01-inch slots. The PVC well screen and blank casing were lowered into the drilling drive casing and the drive casing was then retracted three feet from the bottom of the boring to expose the water-bearing material while maintaining a surface seal. ' A small-diameter bailer was then lowered into the PVC piping and groundwater was decanted from the bailer into laboratory-supplied sample containers. Sample containers were labeled,sealed in . plastic bags,and stored in an ice-cooled chest. \\SF3\DEPTDATA\DOC_SAFE\60005\6115.007\DEC2000REPOR7IBURNS SOILGW RPTNOV00_I.DOC 4