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Tmmweluow <br /> 10 October 2008 <br /> Project: 2597.13 <br /> Ms. Margaret Lagorio <br /> San Joaquin County Environmental Division <br /> 304 East Weber Street, Third Floor <br /> Stockton, California 95202 <br /> Subject: Well Destruction <br /> Unocal and L&M Operable Units <br /> Lincoln and West Weber Avenue <br /> Stockton, California <br /> Dear Ms. Lagorio: <br /> This workplan describes the well destruction program proposed for the Unocal and L&M Operable Units <br /> (OUs). The Site is located on the southwest corner of West Weber and Lincoln Streets in Stockton, <br /> California (Figure 1). <br /> Treadwell &Rolla has been retained by the City of Stockton Redevelopment Agency to conduct soil <br /> remediation under the oversight of the Central Valley Regional Water Quality Control Board (CVRWQCB), <br /> and these wells need to be destroyed prior to the proposed soil excavation work. <br /> BACKGROUND AND CURRENT SITE CONDITIONS <br /> The Unocal OU of Area 2A comprises approximately 2.7 undeveloped acres and is currently vacant. Nine <br /> monitoring wells at the Unocal and L&M OUs will need to be destroyed as part of the removal action and <br /> subsequent Site development. Figure 1 shows the existing monitoring well locations. The proposed <br /> excavation and future development will encroach upon wells MW-5, MW-8, MW-11, and MW-39 on the <br /> Unocal OU, and Wells MW-04, MW-10, MW-40, MW-41 and MW-53 and in the former Harrison Street <br /> portion of the L&M OU. <br /> PROPOSED WELL DESTRUCTION <br /> A total of nine wells are proposed for destruction. All wells will be destroyed by drilling out the casings <br /> and pressure grouting the holes (Table 1). Wells will be abandoned by Precision Sampling Inc., under <br /> oversight from Treadwell &Rollo, Inc. <br /> SCHEDULE <br /> We plan to destroy eight of the nine monitoring wells in late October 2008. One of these wells is inside a <br /> circular concrete vault and will be abandoned several weeks later after the vault is removed. <br /> If you have any questions regarding this workplan please call. <br /> ENVIRONMENTAL AND GEOTECHNICAL CONSULTANTS <br /> 555 MONTGOMERY STREET, SUITE 1300 SAN FRANCISCO CALIFORNIA 94111 T 415 955 9040 F 415 955 9041 www.treadwellrolloxom <br />