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w � W <br /> o The utilities are located at approximate elevations and distances where area will be exposed and <br /> concrete added to secure casing. Consequently, managing pea gravel from caving in the cleared area <br /> and managing concrete from traveling through pea gravel will be problematic. This is especially a <br /> concern at MW-3 which has several utilities located on either sides. <br /> o After concrete dries for a couple days and well is over-drilled,the removal of concrete will require <br /> working in tight spaces,which poses potential safety concerns. Also, the concrete will generate <br /> additional waste to dispose. <br /> • The station is opened 24 hours. The multiple steps involved to install casing will interrupt service station <br /> operations. <br /> In addition, I understand that to:pressure grout,no detectable concentrations of contaminants can be detected,but <br /> wells MW-3 and MW-7 appear to pose a low risk to local aquifer: <br /> • At well MW-3 (screened from 20-40 fbg),only low concentrations of MTBE (1.5µg/L-below WQOs) in <br /> groundwater and TPHg(1.3 mg/kg at 26 fbg) in soil were detected. <br /> • At well MW-7(screened from 25 to 40 fbg), no gasoline constituents were detected in groundwater. Although <br /> low concentrations of gasoline constituents were detected in soil samples(21 and 25 fbg), it is likely that these <br /> concentrations have likely decreased to non-detectable.concentrations through natural attenuation processes <br /> as it has been over 25 years since these samples were collected. <br /> Thank you for considering this request. <br /> Larry J. Silva <br /> Conestoga-Rovers&Associates(CRA) <br /> 10969 Trade Center Drive,Suite 107 <br /> Rancho Cordova,CA 95670 <br /> Phone: 916.889.8914 <br /> Fax: 916.889.8999 <br /> Email: lsilva@craworld.com <br /> www.CRAworld.com <br /> From: Silva, Larry <br /> Sent: Tuesday, June 17, 2014 5:20 PM <br /> To: 'Gabriel Gonzalez [EH]' <br /> Subject: 620 West Charter Way, Stockton <br /> Hi Gabriel, <br /> I received your message about providing additional details on how we plan on destroying wells MW-3 and MW-7. <br /> I'm sorry for the delay in response—I'm waiting to hear back,from driller to get some clarification on the process that I <br /> spoke to you about. I will get back to you first thing tomorrow morning. <br /> Thank you, <br /> Larry J.Silva <br /> Conestoga-Rovers&Associates(CRA) <br /> 10969 Trade Center Drive,Suite 107 <br /> Rancho Cordova, CA 95670 <br /> Phone: 916.889.8914 <br /> Fax:916.889:8999 <br /> Email: Isilva@craworld.com <br /> www.CRAworld.com <br /> 3 <br />