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Rantec Well Destruction Work Plan Stockton Charter Way Commingled Plume August 12, 2011 groundwater system is likely acting as one unconfined to locally semiconfined hydrostratigraphic unit with varying degrees of permeability due to vertical changes in deposits." Vertical migration will be possible at the Site if vertical gradient is applied nearby (i.e., water supply well pumping). Appendix C includes the boring logs for the CMT wells. 2. Even though a California-license drilling contractor and OSHA-approved well destruction provided assurance to SJCEHD for the use of explosives, Stantec and the RPs contest that the use of explosives pose unacceptable risks to the health and safety of the operators and customers of the existing active ARCO-branded service station (440 West Charter Way) and the nearby community. 3. Stantec measured depth-to-water from SMW-18-80 and SMW-18-120 at approximately 17 ft below ground surface (bgs) during the second quarter 2011. Stantec and the RPs believe that the use of explosives below the groundwater will degrade groundwater quality. 2.2 Proposed Alternative Well Destruction Methodology In order to minimize the vertical migration of dissolved petroleum hydrocarbons in the subsurface through the CMT wells, Stantec proposes to pressure-grout each of the six channels, three of which are screened from 70 to 80 ft bgs (SMW-18-80) and the other three from 110 to 120 ft bgs (SMW-18-120). The manufacturer's suggested procedures for decommissioning CMT wells will be utilized (Appendix D). The following describes in detail the permitting, pre-field preparation, and well destruction activities necessary for the proper destruction of wells SMW-18-80 and SMW-18-120. 3.0 WELL DESTRUCTION 3.1 Site-Specific Health and Safety Plan As required by the OSHA "Hazardous Waste Operations and Emergency Response" guidelines (29 CFR 1910.120) and by California Occupational Health and Safety Administration (Cal-OSHA) "Hazardous Waste Operations and Emergency Response" guidelines (CCR Title 8, Section 5192), the contractor will prepare a site-specific Health and Safety Plan (HASP). At a minimum, the HASP will define the proposed subsurface investigation activities, describe physical and chemical hazards that may be associated with the work, provide a map to the nearest emergency medical facility, and include material safety data sheets for hazardous chemicals that will be used or produced during the work. A copy of the HASP will be available on-site at all times during field work. The field staff and subcontractors performing field activities will review the HASP prior to beginning field operations, as described in this work plan, at the Site. Stockton Charter Way Commingled Plume Well Destruction Work Plan.doc 3