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Mr. Harlin Knoll, SJCEHD September 29,2005 Site Investigation Work Plan 103 North E Street, Stockton, CA Page 6 pressure grouted from the bottom of the borehole up to surface grade. Locations of the CPT borings and number of grab groundwater samples may be changed by the supervising Professional based on conditions encountered in the field. Task 3: Laboratory Analysis Groundwater samples will be forwarded to a state-certified analytical laboratory for chemical analysis. The samples will be analyzed for TPHG using U.S. Environmental Protection Agency (USEPA) Method 8015B/DHS LUFT, and for BTEX, MTBE, TBA, 1,2-DCA, tertiary amyl methyl ether (TAME), Ethyl Tertiary Butyl Ether (ETBE), Di-isopropyl Ether (DIPE), and dibromoethane (EDB) using USEPA Method 8260B. Task 4: Report Preparation After completing the field activities and receiving the laboratory results, Stratus will prepare a report of the findings from the CPT investigation. This report will include, but may not be limited to, a scaled site plan, a groundwater sampling log, analytical data tables, certified analytical reports, and a geologic cross section. This report will also include an evaluation of whether the hydrogeologic conditions and extent of 1,2-DCA impact have been adequately characterized. Based on the findings of the CPT investigation, Stratus will prepare an addendum to this work plan to install a groundwater monitoring well network. The proposed monitoring wells will be installed to provide general hydrologic data(groundwater flow direction and gradient), and will also be targeted at specific potential migration pathways identified in the CPT study. If the first phase of investigation concludes that hydrogeologic conditions or the extent of 1,2-DCA impact has not been adequately characterized, the work plan addendum will also propose additional assessment activities. If conditions appear adequately characterized, Stratus will prepare a risk analysis for the site. The results of the risk analysis will determine if risk-based NFA can be pursued, or it other actions are necessary. SCHEDULE Following approval of this Work Plan, a drilling permit will be secured from SJCEHD and a C-57 licensed contractor will be contracted to perform the proposed CPT activities. We anticipate that it will take at least four weeks for the drilling contractor to become available. The proposed CPT activities will take approximately two weeks to perform. Laboratory analytical reports should be received within four weeks of completion of CPT activities. The report for the CPT investigation will be submitted approximately six weeks after receipt of all analytical data. The work plan addendum will be submitted approximately four weeks after regulatory concurrence with the findings and recommendations of the CPT report. KATeichert\Stockton-1031Work PlansVeichert workplan 09-2005.doc STKAWO