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Page 1 of 2 <br /> Vicki McCartney [EH] <br /> From: Mike Sonke [mike.sonke@cardno.com] <br /> Sent: Tuesday, July 02, 2013 4:44 PM <br /> To: Vicki McCartney [EH] <br /> Cc: John Yoakum [EH] <br /> Subject: Update: Monitoring Well Destruction Fmr Food & Liquor 15 E. Grant Line Rd. Tracy <br /> Attachments: Fmr Food and Liquor 15 E. Grant Line Rd Tracy Obstructed Well Photos.pdf <br /> Hi Vicki, <br /> As I suspect you have heard from Johnny Yoakum,we were unable to destroy four of the monitoring wells at the <br /> former Food & Liquor 15 E. Grant Line Rd.Tracy. <br /> Three of the monitoring wells(MW1, MW3, and MW4)were constructed with a what appears to be a conductor <br /> casing which prevented their overdrilling that were not reflected on the well logs. In addition, the two other <br /> wells had physical obstructions that prevented the placement of the drill rig over the wells. MW1 was <br /> obstructed by a tree and MW2 was obstructed,by a,block wall. Please see the attached pictures from the site. <br /> We have been working with the driller,Woodward Drilling,-to come up with a potential solution to the issues, <br /> and want to get your input. <br /> Due to the relatively short, 5-foot long well seals in the affected wells,we are proposing to use an air knife to <br /> remove the soil encircling the well box and well seal, down to the end of the well seal,—5-feet bgs. The original <br /> boring logs show each of the wells have a 5-foot long well seal.After removing the supporting soil, we are <br /> proposing to cut the casing at the base of the well seal, and hoist the well box and well seal out of the ground as <br /> a complete unit, leaving the casing in place in each of the four wells. From that point,two different methods <br /> will be used to finish the destruction. <br /> For the non-obstructed monitoring wells MW3 and MW4, we are proposing to proceed as originally proposed <br /> and overdrill the remaining casing, screen and construction materials and grout up the borehole. <br /> For the obstructed wells, MW1 and MW2 we are proposing to use an air knife to remove the soil and the sand —7 <br /> pack materials from around the remaining casing and screen to the excavation depth limitations of the air knife. <br /> Then we are proposing to attempt to remove the casing and grout up the resulting voided space. If it appears <br /> that the entire casing�cannot be exposed due to high groundwater, excessive soil sloughing or Limits of the air <br /> knife, it has been suggested that perhaps the casing/screen could perhaps function as a tremmie pipe, by <br /> knocking out or cutting off the terminal cap and filling the void with grout, as the casing/well screen is extracted. <br /> Does this sound acceptable? <br /> If so, do you need me to amend the workplan to reflect this? <br /> Please call me if you have questions or concerns. <br /> Thanks! <br /> Michael D. Sonke <br /> PROJECT MANAGER I BUSINESS DEVELOPMENT I GHG VERIFIER <br /> CARDNO ATC <br /> 7/5/2013 <br />