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%ftwl 1�j Ms.Margaret Lagorio,SJCEHD December 31,2003 Joe's Truck Plaza Project No.2033-15600-01 Work Plan Addendum Page 3 In a letter dated December 8, 2003, SJCEHD rejected the Work Plan due to a decline in petroleum hydrocarbon concentrations from second to third quarter 2003, and because SJCEHD concluded that the new monitoring data and the dissolved hydrocarbon mass estimate in the SCM did not warrant the scope of investigation and remediation proposed in the October 21, 2003, Work Plan. SCOPE OF WORK Eight (8) CPT borings will be advanced at the locations shown on the Site Plan and Site Vicinity Map (Figure 2 and 3). Each CPT boring will each be advanced to a depth of approximately 80 feet bgs by a California-licensed well driller. 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 hole will be pressure grouted from the bottom of the borehole up to surface grade. The initial 5 feet of each boring will be advanced with a hand auger and/or posthole digger to reduce the possibility of damaging underground utilities. The proposed locations of the CPT borings should allow adequate characterization of the lateral and vertical extent of the upper and lower sandy strata identified during previous subsurface investigations. In addition, these CPT borings should be deep enough to evaluate if the second, deeper water-bearing zone, identified beneath the Sharpe Depot, extends beneath the Joe's facility. Following the CPT work, a separate boring will be advanced immediately adjacent to each of the CPT boring locations. These borings will be advanced with the CPT rig using the direct-push methodology. Soil and groundwater samples will be collected from each of the borings to further characterize the vertical extent of petroleum hydrocarbon impact. Although the actual number of samples collected and submitted for analysis will depend on conditions encountered in the CPT borings, Stratus anticipates that at least five soil and five grab groundwater samples will be collected from each of these borings. Hydropunch° sampling equipment will be used to collect the groundwater samples at the desired depths. The Hydropunch° sampler will be pushed approximately 2 feet below the bottom of the borehole, and the screen interval exposed, to allow for the collection of depth discreet groundwater samples. Procedures pertaining to the use of the Hydropunch° and collection of samples are detailed in Appendix A. Upon completion of sampling, the direct-push boring will be pressure grouted from the bottom of the borehole up to surface grade. Soil and grab groundwater samples will be handled and analyzed as described in the original Work Plan. Following completion of the CPT study, including construction of one geologic cross-section parallel to the plume axis and one perpendicular to the plume axis, P:Voe's Truck Plaza\Work PlansVoes wp addendum 123103.doc