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