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r � Mr Harlan Knoll April 24, 2000 Page 3 Proposed CPT Soil Boring To confirm the cleanup of vadose zone soil currently under remediation by soil vapor extraction, and to evaluate the vertical extent of any impacted groundwater-bearing zones beneath the former USTs, a series of soil borings will be advanced at one location using a CPT rig The proposed CPT Iocation is shown on the attached Figure I The proposed trace of the CPT borings are shown in cross-section on the attached Figures 2 and 3 The borings will be drilled under permit from PHS/EHD The initial CPT boring will be advanced to a total depth of approximately 100 feet As the cone penetrometer is advanced, tip resistance, sleeve friction and pore water pressure will be recorded at five-centimeter intervals These data will be processed and interpreted in the field Based on the results of the CPT sounding, separate soil borings will be drilled adjacent to the first boring for depth-discrete soil and groundwater sampling The second soil boring will be used to collect a set of soil samples Beginning at 10 feet bgs, soil samples will be collected approximately every 10 feet with a direct-push sampler to confirm the cleanup of vadose zone soil and to define the vertical extent of impacted soil . below the groundwater table The exact soil sample depths will be based on the results of the CPT sounding A separate and dedicated soil boring will be advanced for each desired depthdiscrete groundwater sample At the desired depth in each soil borigg, a Hydropunch wilf,1 p deployed, and groundwater samples will be collected with a bailer Target grounder- bearing zones will be identified from the CPT soundings and pare pressure tests Following sampling, each of the soil borings will be sealed with neat cement grout The grout will be placed using plastic tremae pipe All of the soil and groundwater samples will be properly packaged and transported in an iced cooler with chain-of-custody documentation to a state of California certified hazardous waste testing laboratory for analysis The lab will analyze the samples for TPH-as-gasoline, benzene, toluene, ethylbenzene, xylenes (BTEX), MTBE, di-isopropyl ether(DIPS), ethyl tertiary butyl ether(ETBE),tertiary amyl methyl ether(TAME), tertiary butanol (TBA), 1,2- dichloroethane (1,2-DCA), and 1,2-dibromoethane (EDB) by EPA Method 8260B The results of the investigation will be documented in a report,to be prepared and stamped by a state of California Registered Geologist Given standard turnaround for regulatory review and approval of this work plan, and cost pre-approval from the UST Cleanup Fund, the project could begin as soon as May 2000 If the field work could be completed during . June 2000, the project report could be completed as early as July 2000