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II Mr. Harlin Knoll, SJCEHD September 29,2005 Site Investigation Work Plan 103 North E Street, Stockton,CA Page 5 I geologic work will be conducted under the direct supervision of a State of California Professional Geologist or Civil Engineer, and will be conducted in accordance with standards established by the RWQCB (Recommendations for Preliminary Investigation and Evaluation of'Underground Tank Sites, April 2004) and SJCEHD guidelines. A California-licensed C-57 well contractor will perform all soil boring activities. A copy of Stratus' field practices and procedures that will be utilized during this work is provided in Appendix C. Task 1: Pre-field Activities Following approval of this Work Plan, the following activities will be completed: • Obtain soil boring permits from SJCEHD, • Retain and schedule a licensed C-57 drilling contactor, • Update the health and safety plan for the site, • Mark boring locations and contact Underground Service Alert to locate underground utilitiesin the vicinity of the work site, and • Notify SJCEHD and Teichert of the scheduled field activities. Task 2: Field Activities r CPT Borings and Soil and Groundwater Sam lin Stratus will oversee a California licensed drilling contractor advance eleven CPT borings to approximately 150 feet bgs (or equipment refusal). The proposed CPT locations are shown on Figure 2. The CPT consists of advancing a cone-tipped cylindrical probe (1.7 inches in diameter) into the ground while simultaneously,,measuring the resulting resistance to penetration. A computer generated CPT log is plotted in the field, providing a continuous log of site lithology. Upon completion of sampling, the CPT holes will be pressure grouted from the bottom of the borehole up to surface grade. Following the CPT work, depth-discrete grab groundwater samples will be collected from a separate boring, located approximately 2 feet from the initial CPT boring. The number of grab groundwater samples collected from each of the direct push borings will be based on the strata encountered during CPT, and also on strata encountered in nearby borings previously drilled. Hydropunchrm sampling equipment will be used to collect the groundwater samples at desired depth intervals, based on the continuous log generated from the CPT. The HydropunchTm sampler will be pushed to the bottom of the sampling interval using 2-inch diameter steel rods. The: steel rods are subsequently retracted approximately four feet, exposing the screen to allow for the collection of depth discrete groundwater samples. Upon completion of sampling,,the direct-push boring will be KATeicbert\Stockton-1031Work Planslteichert workplan 09-2005.doe STRATUS