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GEOCON <br /> CONSULTANTS,INC. <br /> GEOTECHNICAL ■ ENVIRONMENTAL ■ MATERIALS <br /> Project No. S9482-06-02 <br /> January 5, 2012 <br /> Mr. Mike Infurna RECEIVE® <br /> San Joaquin County <br /> Environmental Health Department <br /> 600 East Main Street JAN 0 6 2012 <br /> Stockton, California 95202-3029 <br /> ENVIRONMENTAL HEALTH <br /> Subject: 5400 AND 5606 PACIFIC AVENUE PERMIT/SERVICES <br /> STOCKTON, CALIFORNIA <br /> CLEANUP AND ABATEMENT, ORDER NO. 5-00-707 <br /> CASE NUMBERS 390258 AND 390014 <br /> CHEVRON#306620(FORMER UNOCAL#5098) <br /> WELL DESTRUCTION WORKPLAN ADDENDUM <br /> Dear Mr. Infurna: <br /> As requested by the San Joaquin County Environmental Health Department (SJCEHD), we have <br /> prepared this addendum to AECOM's Well Destruction Workplan (Workplan) dated April 2011 for <br /> groundwater monitoring and remediation well destruction activities to be conducted at the former <br /> Montgomery Wards, LLC (Wards) auto service center located at 5400 Pacific Avenue and the former <br /> Unocal service station#5098 (Chevron Facility No. 306620), located at 5606 Pacific Avenue in Stockton, <br /> California. The Wards and Unocal sites are collectively referred to as the Site. These revisions are a <br /> result of multiple email conversations with Mike Infurna and Nuel Henderson of the SJCEHD regarding <br /> concerns with the procedures and methods outlined in the Workplan. The approximate site location is <br /> shown on Figure 1.The approximate locations of the wells to be destroyed are depicted on Figure 2. <br /> SCOPE OF SERVICES <br /> Field Activities <br /> Eighty-nine groundwater and remediation wells will be destroyed by either pressure grouting or <br /> overdrilling techniques. The proposed destruction method for each individual well is shown on Table <br /> 1. Descriptions of the methods and procedures involved with each of these proposed methods are <br /> presented below. <br /> Drilling Out 2-Inch-Diameter and 4-Inch-Diameter Polyvinyl Chloride (PVC) Wells Using <br /> a Hollow-Stem Auger Drilling Ria <br /> Wells MW-2, MW-3, MW-11, MW-16, MW-32, AS-33, VEW-IA, VEW-113, VEW-2A, VEW-213, <br /> VEW-3, VEW-4 and VEW-5 will be destroyed by drilling out the casing and annulus to the total depth <br /> of each well using a hollow-stem auger drilling rig equipped with a self-centering "stinger" bit. If the <br /> self-centering "stinger bit" should malfunction or be deemed unsuitable, appropriately sized drilling <br /> rods will be placed down the annulus of the well and augered around to ensure the augers stay <br /> centered on the well. The augers used to drill out each well will be at least the same size as was used <br /> when the wells were installed (8-, 11- and 12-inch-diameter). These wells are constructed of 2-, 3- and <br /> 3160 Gold Valley Drive,Suite 800 0 Rancho Cordova,CA 95742-7515 ■ Telephone 916.852.91 18 ■ Fax 916.852.9132 <br />