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Geosyntec <br /> consultants <br /> may be adjusted by Geosyntec based on observations made during borehole advancement and <br /> results of continuous soil sampling. <br /> 4. METHODS <br /> The following sections describe the methods proposed for implementing the proposed <br /> destruction of monitoring wells MW-5B and MW-7B and the installation and development of <br /> two new monitoring wells MW-5C and MW-7C. <br /> 4.1 Notifications and Permitting <br /> Prior to the start of field activities,the following will be performed: <br /> • A C-57 licensed driller will be subcontracted for the destruction of MW-5B and <br /> MW-7B and installation and development of new monitoring wells MW-5C and <br /> MW-7C; <br /> • Approval for the proposed work will be obtained in writing from the CRWQCB; <br /> • Site Mitigation Well and Boring Permits (one for well destruction, one for well <br /> installation)will be obtained from the San Joaquin County Environmental Health <br /> Department(SJCEHD); <br /> • Proposed monitoring well locations will be marked with white paint and USA North <br /> 811 will be contacted a minimum of 48 hours prior to the commencement of <br /> intrusive subsurface activities; <br /> • A health and safety plan in the form of a Task Hazard Analysis (THA) will be <br /> provided to the drilling contractor before mobilizing to the Site; and <br /> • The SJCEHD and the CRWQCB will be notified of the planned work schedule at <br /> least 48 hours prior to start of field activities. <br /> 4.2 Destruction of Damaged Monitoring Wells MW-5B and MW-7B <br /> A C-57 licensed drilling contractor (PeneCore Drilling of Woodland, California) will be <br /> subcontracted by Geosyntec to destroy monitoring wells MW-5B and MW-7B in accordance <br /> with applicable SJCEHD requirements. Geosyntec will be present during the well destruction <br /> activities to direct and document the work.Well destruction will be performed by over-drilling <br /> using hollow stem auger methodology with 10-inch diameter augers. The well construction <br /> materials within the original borehole will be removed(including the well casing,screen,filter <br /> pack,and annular seal),after which the created hole will be filled completely with appropriate <br /> sealing material in accordance with San Joaquin County Well Standards. The created hole <br /> OxyChem-Stockton MW Replacement Work Plan 7.18.25 3 2025.07.18 <br />