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S ECOR <br /> 7-Eleven Store#14117 <br /> Work Plan for Additional Site Assessment <br /> July 27, 2004 <br /> Page 3 <br /> In response to the SJCEHD's request for interim remediation, SECOR submitted a Work <br /> Plan for Interim Remediation and Oxygen Injection Feasibility Test, dated April 19, 2004. <br /> The work plan proposed TBA plume migration via periodic groundwater extraction at least <br /> once a month from existing monitoring wells MW-1, MW-2, and MW-4. In addition, three <br /> oxygen injection wells were proposed to evaluate the effectiveness of oxygen injection for <br /> enhancing in-situ biodegradation of the residual hydrocarbons in soil and groundwater. The <br /> SJCEHD did not approve the work plan due to inadequate groundwater extraction <br /> frequency, and the potential requirements of the California Regional Water Quality Control <br /> Board (RWQCB) for a waste discharge evaluation prior to injection of oxygen into <br /> groundwater. The waste discharge evaluation would potentially entail bench-scale testing <br /> of general mineral/metal solubility due to oxygen injection. <br /> SCOPE OF WORK <br /> SECOR proposes installing two offsite groundwater monitoring wells (MW-9 and MW-10), <br /> and advancing three offsite soil borings (GP-1 through GP-3) and three CPT borings (CPT- <br /> 1 through CPT-3). Data obtained from the drilling and installation of the monitoring wells <br /> and soil borings will be used to further delineate the lateral and vertical extent of MtBE and <br /> TBA present in underlying soil and dissolved in groundwater. <br /> Site Health and Safety <br /> As required by the Occupational Health and Safety Administration (OSHA) Standard <br /> "Hazardous Waste Operations and Emergency Response" guidelines (29 CFR 1910.120), <br /> and by California Occupational Health and Safety Administration (Cal-OSHA) "Hazardous <br /> Waste Operations and Emergency Response guidelines (CCR Title 8, Section 5192), <br /> SECOR will prepare a Site-Specific Health and Safety Plan prior to the commencement of <br /> field work. The Site-Specific Health and Safety Plan will be reviewed by the field staff and <br /> contractors before beginning field operations at the site. <br /> Permitting, Utility Location, Access Agreements, and Encroachment Permits <br /> The permits for the groundwater monitoring well installations and soil borings will be <br /> obtained from the SJCEHD. Access agreements will be obtained from each property owner <br /> prior to beginning the offsite work (MW-9, CPT-2, and GP-1 through GP-3). An <br /> encroachment permit will be obtained from the City of Stockton to allow installation of MW- <br /> 10 and CPT-3 in the public right-of-way. SECOR will contact Underground Service Alert at <br /> least 48 hours prior to beginning drilling. A private utility locator will also be used to identify <br /> the location of underground utilities in the area surrounding the proposed well and boring <br /> locations. In addition, the boring locations will be hand-cleared to 5 feet bgs prior to <br /> beginning drilling activities. <br /> Soil Borings, Soil Sampling and Analysis <br /> Prior to drilling, all soil boring locations will be cleared using a hand auger to five feet bgs to <br /> minimize risk of underground utility line damage. Downhole drilling equipment will be steam <br /> File:7-11/14117 WP for additional assessment(July 04).doc SECOR International Incorporated <br />