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OIL URS Mr. Robert McClellon January 31, 2012 Page 2 groundwater. To assess the presence or absence of VOC constituents in groundwater,three groundwater monitoring wells were installed at the site on June 12,2006. Following the installation of the ground- water monitoring wells, groundwater samples were collected quarterly and analyzed for VOCs.Mr. Ross Atkinson of the Regional Water Quality Control Board(RWQCB), Central Valley Region,requested that groundwater samples be collected and analyzed for metals and general minerals(only total dissolved solids [TDS] after the first event) starting in 4Q06. In a meeting on May 24, 2007,Mr.Atkinson concurred with the recommendation in the Quarterly Monitoring Report dated April 30,2007,to suspend the groundwater monitoring activities for VOCs. In the 1Q11 letter report to SJCEHD dated April 29,2011,URS recommended reducing the frequency of the monitoring activities from quarterly to annually. SJCEHD agreed with URS'recommendation. In a letter to RWQCB dated May 20, 2011,URS recommended no further action for groundwater activities. RWQCB agreed that on-site groundwater issues had been resolved to their satisfaction and issued a letter to proceed with well decommissioning on December 2, 2011 (Attachment A). A letter work plan dated describing the well decommissioning activities along with the completed Well/Pump Permit, associated permit fees, and health and safety plan were transmitted to SJCEHD on December 1, 2011. SJCEHD approved the work plan and well/pump permit(Attachment B)prior to the start of the field activities to decommission the three groundwater monitoring wells. FIELD ACTIVITIES The follow two sections described field activities related to decommission the three groundwater monitoring wells and the annual monitoring activities. Well Decommissioning Activities Utility Clearance.URS marked the excavation areas in white paint and notified Underground Service Alert(USA)on December 6, 2011. Health and Safety.URS conducted a health and safety meeting with all field staff, including subcontractors,before field work began. Well Decommissioning. On December 9, 2011,URS provided oversight to Precision Sampling of Stockton, California, during decommissioning of the monitoring wells to verify that the work was conducted in accordance with all applicable state and local regulations. Additionally, SJCEHD was present to observe all decommissioning activities. Well construction logs indicated the monitoring wells were constructed of 2-inch-diameter polyvinyl chloride and were screened at various intervals between 10 and 29 feet below ground surface(bgs). The flush-mounted well cover, concrete pad, and bollards were removed before decommissioning. Each well was pressure-grouted from total depth to near surface and capped with using Portland Type 1/11 cement H:\Wprocess\25532\WoddEnterprise\Radio ShackMecomm_Annual Rpffext.doc