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�.., S ECOR <br /> 7-Eleven Store#20632 <br /> Offsite Assessment Work Plan <br /> June 18, 2004 <br /> Page 2 <br /> Local Hydrology <br /> Depth to groundwater in the site monitoring wells has ranged between approximately 5 and 8 feet <br /> bgs (based on MW-1) (Table 1). The groundwater flow direction has historically been toward the <br /> south and southwest. <br /> SCOPE OF WORK <br /> SECOR proposes collecting grab groundwater samples from eight offsite soil borings to evaluate the <br /> downgradient extent of MtBE and tert-butyl alcohol (TBA) dissolved in groundwater. Data obtained <br /> from the advancement of the soil borings will be used to confirm the presence and nature of <br /> hydrocarbons in soil and groundwater. The following scope of work is proposed. <br /> HEALTH AND SAFETY <br /> SECOR will modify our existing site-specific Health and Safety Plan for the proposed scope of work <br /> as required by the Occupational Health and Safety Administration (OSHA) Standard "Hazardous <br /> Waste Operations and Emergency Response" guidelines (29 CFR 1910.120). The document will be <br /> reviewed and signed by SECOR personnel and subcontractors performing work at the site. <br /> PERMITTING AND UTILITY CLEARANCE <br /> SECOR will obtain permits from the SJCEHD to advance eight soil borings into groundwater. <br /> Access agreements will be obtained for the soil borings located in the East Bay Municipal Utility <br /> District (EBMUD) parcel south of the site. Prior to conducting subsurface work at the site, <br /> Underground Service Alert (USA) will be contacted to delineate subsurface piping near the site with <br /> surface markings. In addition, a private utility locator service will be contracted to clear the area <br /> surrounding the proposed soil borings. <br /> SECOR obtained a map (Attachment B) from EBMUD showing the locations of their three water <br /> mains, in addition to a high-pressure oil pipeline (owned and operated by others) in the EBMUD <br /> parcel. SECOR will request an EBMUD representative be onsite when locating borings to minimize <br /> interference with their pipeline operations. <br /> SOIL BORINGS <br /> Soil Boring, Soil Sampling and Analysis <br /> Sail borings will be drilled at the locations depicted on Figure 2 using a truck-mounted Geoprobe° <br /> drilling rig equipped with a 2-inch-diameter direct-push sampler. Each boring will be advanced to a <br /> depth of approximately 8 feet bgs. The eight borings will have soil samples collected at 5 and 8 feet <br /> using a split spoon sampler lined with 2-inch diameter by 6-inch-long brass sample tubes (Table 2). <br /> Downhole drilling equipment will be steam cleaned before drilling each borehole, and sampling <br /> equipment will be cleaned between each sampling interval. Each soil sample will be screened for <br /> hydrocarbon vapors using a portable photoionization detector (PID). Soils encountered during <br /> drilling will be logged using the Unified Soil Classification System by a SECOR field geologist, <br /> working under the supervision of a California Registered Geologist. <br /> 20632 Offsite Assessment.doc SECOR International incorporated <br />