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ARCADIS Infrastructure, environment, buildings R Fc:�,Crf NED ARCADIS mU.in mc. 3240 EI Camino Real Suite 200 AUG 1 " 2010- Irvine California 1385 ENVIRONMENT*HEALTH Tel 714.730.9052 Ms. Kristi Shelton PERM IT/SERVYCE.S Fax 714.730.9345 California Regional Water Quality Control Board www.arcadis-us.com Central Valley Region 11020 Sun Center Drive, Suite 200 Rancho Cordova, California 95670-6114 ENVIRONMENTAL Subject: Well Destruction Corral Hollow and Grant Line Roads Site Tracy, California Date: August 16, 2010 i Dear Ms. Shelton: contact: Mr. Dana Koschel On behalf. of Chevron Environmental Management Company (Chevron EMC), ARCADIS U.S., Inc. (ARCADIS) has prepared this correspondence to document the Phone: proper destruction of the six existing wells at Corral Hollow and Grant Line Roads 714.730.9052 Ext 13 site located in Tracy, California (Figure 1). Destruction of monitoring wells MW-5, email: MW-6, MW-7, MW-8, and MW-12; and groundwater extraction EX-6 was approved Dana.KoschelQarcadis- by the California Regional Water Quality Control Board — Central Valley Region us.com (Regional Board) in their letter dated July 16, 2010. Destruction of the wells was required by the City of Tracy to allow for the widening of Grant Line Road. our ret: B004701 1.0000.00001 Prior to conducting the field activities, ARCADIS secured a well destruction permit from San Joaquin County Environmental Health Department (SJCEHD). A copy of the permit is included as an attachment. ARCADIS contracted Cascade Drilling, LP (Cascade) of Rancho Cordova, California to properly destroy the wells. Cascade is a California-licensed drilling contractor (C57 License No. 938110). Wells MW-5, MW- 7, MVV-8, and EX-6 were destroyed on July 27, 2010. Monitoring wells MW-6 and MW-12 were destroyed on July 28, 2010. All well destructions were supervised by Mike Infurna of the SJCEHD. Prior to destruction, the well box and concrete securing each well box was removed by Cascade. The wells were overdrilled to a depth 1-foot below the total depth of the well using a hollow-stem drill rig. The diameter of the auger used was large enough to remove all well casing, filter pack, and annular seal material. A tremie pipe was then utilized to backfill the resulting borehole with a neat cement grout, from the bottom upward, to an approximate' depth of 5-feet below ground surface. The Imagine the result gAcommon\allen\chevron o&m\corral hollow\well destruction\well destruction_08.16.10.doc }