SITE INFORMATION AND CORRESPONDENCE

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e ' page 2, 15634 Steinegul Rd.• Well MW-6, which is screened from 95-100 feet bsg, has the second highest ' concentration of contaminants, after shallower well MW-2. A grab groundwater sample collected from CPT-1 at 124 feet bsg had reportable concentrations of petroleum hydrocarbons. SJC/EHD approves the installation of one deep groundwater monitoring well onsite, in the area of MW-2/MW-6/CPT-1, but recommends placement of a short, discrete screen at approximately 124 feet bsg, across the apparent permeable unit identified and targeted for sampling in the CPT boring. The boring for this deep well should be continuously cored across the target depth interval to obtain a hard data-based soil profile and to ensure screen placement in a water-bearing zone. If, after appropriate well development and several quarters of monitoring and sampling this well exhibits contamination, further vertical assessment may be necessary. Please proceed with submittal of the addendum, and a SJC/EHD boring permit application and required fees ($89.00 permit fee and $294.00 inspection fee)for each parcel of land on which work will be done. Submit also access agreements and/or encroachment permits for offsite work. The addendum is due no later than September 28, 2007. Following completion of the CPT borings and installation of the deep monitoring well, a report of findings must be submitted in the form of a Site Conceptual Model (SCM) that contains updated cross-sectional diagrams and an evaluation of the necessity for additional wells to complete plume definition. The SCM is due within 60 days following completion of the fieldwork. If you have any questions please call Lori Duncan at (209) 468-0337. Donna Heran, REHS, Director Environmental Health Department ('0AA � Lori Duncan, Senior REHS Nuel C. Henderson, Jr., PG LOP/Site Mitigation Unit IV LOP/Site Mitigation Unit IV cc: James Barton, CVRWQCB Lorraine Sawyer, ATC