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Wong,Jeff From: John Lane <jlane@condorearth.com> Sent: Monday, April 13, 2020 8:57 PM To: Kith, Michael Cc: Wong,Jeff; Karli Stroing (karli@vwdrill.com) Subject: FW: Well Destruction Permit Application for former Ranch Market, 23569 S. Santa Fe Avenue, Riverbank, CA Attachments: Ranch Market Well Dest Status 20200413.pdf Michael, Following up on my voice mail today regarding well destructions ongoing at 23569 S. Santa Fe, Riverbank/Escalon. The permit#s for the destructions are WP0040073 and WP0040072 (see attached pdf, pages 1 and 2).Jeff Wong has been handling grout inspections daily since last Monday, April 6th.Jeff may have filled you in on some difficulties we are having at the Site related to overdrilling several 3/-inch air sparge wells.The wells are generally installed to a depth of approximately 43 feet within an 8-inch diameter borehole. You probably recall that the Well Destruction Work Plan approved by the Water Board recommended pressure grouting (and overdrilling the upper 5 feet) of all of the 3/-inch sparge wells, even though this method is not in line with San Joaquin County EHD's policy to overdrill all wells for which soil samples cannot document ND results in soil during installation.The primary reasons for my recommendation to pressure grout were twofold, as stated in the work plan: 1. The annulus around the%-inch casing consists of neat cement grout from just below the ground surface to a depth of approximately 37 feet bgs, and the filter pack of each well (generally from 37-43 feet) lies completely within a well graded sand (SW) at that depth (some logs noted gravel and cobbles at depth as well); 2. Overdrilling is difficult on small diameter wells because the drilling contractor does not have a pilot "reamer" small enough to effectively remain centered over the well to the full installation depth, which typically results in "skipping" off the grout "plug" in the well bore. So, unlike with 2-inch and larger wells, rather than removing the casing generally in whole,the PVC of the sparge wells are typically pulverized and removed in the cuttings.The result is a "messy" hole to re-grout. Also,the overdrilled bore hole is using not completely vertical. However, after discussions with Linda Turkatte of EHD, Condor was not permitted to pressure grout all of the%-inch sparge wells; only those deemed outside of the zone of soil contamination were allowed to be pressure grouted. To date, Condor and V&W Drilling have successfully over-drilled all of the vapor extraction wells(V-1 through V-10), except for well V-3,which is located within 3 feet of an existing PG&E line.V&W has requested an on-site meeting with PG&E (has not yet confirmed meet date/time)to evaluate the safety of over drilling well V-3 and 5-10, both of which are very near a marked gas line. Sparge wells S-1, S-2, S-3, 5-14, 5-15, 5-16, 5-17, 5-18, 5-19, and 5-20 have been pressure grouted with overdrilling the upper 5 feet (well 5-13 has not yet been pressure grouted). However,V&W has encountered difficulty in overdrilling the remaining sparge wells. Of the four%-inch wells that we have attempted to overdrill thus, we were able to overdrill and grout only well 5-12, the northeastermost sparge well (see attached map, page 3 of pdf attachment).V&W encountered an obstruction at approximately 13 feet in the bore holes for 5-11, S-7, and S-9. 5-11 was the second sparge well overdrilled (S-12 was the first) and V&W could not advance past 13 feet. Since the well logs noted "Driller notes cobbles from 12 to 14 feet"V&W used heavy drill rods to punch through the obstruction and proceeded to drill to depth (43 feet). However, during the grouting process, the augers could not be removed and could not be rotated.After considerable effort to remove the rods,V&W pumped out the added grout and contracted a crane to mobilization to the Site to aid in removal of the augers.Two progressively larger cranes and a much larger drilling rig were unable to move the augers, which remain in the ground.The same obstruction was encountered in wells S-7 and S-9 at approximately 13 feet so V&W stopped drilling until it could be determined how to 1