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Swtec Well Restoration and Well Destruction Report Stockton Charter Way Commingled Plume No. CP0057 November 15, 2011 but were unsuccessful. Stantec stopped the well restoration field activities and rescheduled at the earliest date with a surveyor to relocate the wells using existing well surrey data. WDC backfilled the exposed area using native soil and sand and resurfaced with concrete. On October 6, 2011, Stantec personnel used a global positioning system device and existing well survey data to relocate and remark wells SMW20-83.5 and SMW-23. After pinpointing the well locations, WDC began asphalt coring and jackhammering, exposed the well casings via air- knife at approximately three feet bgs, and extended the well casings to near ground surface using two inch diameter Schedule 40 polyvinyl chloride unions, pipes, and plugs. WDC backfilled the well borehole using grout to one foot bgs, installed a traffic-rated well vault, and resurfaced the ground using black-dyed concrete to match the existing surface. Ms. Lori Duncan of the SJCEHD was at the property location to oversee the well restoration activities at different times. 2.5 Well Destruction Activities Stantec oversaw WDC Exploration and Wells of Zamora, California (WDC) jackhammer each well vault skirt and air-knife the soil surrounding wells SMW-7, SMW-18-80, and SMW-18-120 to approximately eight feet bgs on October 3, 2011. Air-knifing ensures that underground utilities do not exist within the well borehole prior to well destruction activities. Stantec also verified that no obstructions exist inside of each well casing to be destroyed and measured the depth-to- water and depth-to-bottom of SMW-7 at 17.26 feet bgs and 41.48 feet bgs, respectively. After the jackhammering and air-knifing activities, WDC backfilled the exposed well boreholes using native soil and used asphalt cold patch to resurface the ground. Prior to well destruction activities, Stantec personnel performed lock-out-tag-out procedure on October 5, 2011 to isolate energy from an electrical wiring and conduit found near SMW-7. Stantec then supervised WDC over-drill SMW-7 including the well casing and materials within the original borehole using a sonic drill rig equipped with ten inch diameter augers. After over- drilling activities, WDC pressure-grouted the SMW-7 well borehole using approximately 150 gallons of neat cement. WDC resurfaced SMW-7 well borehole using black-dyed concrete to match the existing ground surface. Following the over-drilling of well SMW-7, WDC also pressure-grouted the SMW-18-80 and SMW-18-120 well casings using neat cement on the same day per SJCEHD request. Between October 6 and 7, 2011, WDC over-drilled continuous multichannel tubing (CMT) wells SMW-18-80 and SMW-18-120 using a sonic drill rig equipped with six and 7-5/8 inch diameter augers and a "cutoff' drill bit. At 10 feet intervals to a total depth of approximately 120 feet bgs, the 7-5/8 inch diameter auger was first advanced around the well grout column, then mud and/or fluids was flushed out within the auger, followed by advancing the six inch diameter auger around the well casing within the outer auger, and then followed by well casing removal. After over-drilling activities, WDC pressure-grouted the CMT well borehole using approximately 375 gallons of neat cement. WDC resurfaced CMT well borehole using black-dyed concrete to match the existing ground surface. Ms. Lori Duncan, Mr. Mike Infurna, Mr. Nuel Henderson, and Ms. Adrienne Ellsaesser of the SJCEHD were on-site to oversee the well destruction activities at different times. Stockton Charter Way CP-Well Restoration and Well Destruction Report.doc 3