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<br /> <br />Central Valley Regional Water Quality Control Board <br />7 March 2022 <br /> <br />Via e-mail <br /> <br />Mr. Roger Smith <br />Glenn Springs Holdings, Inc. <br />Roger_Smith@oxy.com <br /> <br />REVIEW OF SHALLOW INJECTION WELL INSTALLATION WORK PLAN, FORMER <br />OCCIDENTAL CHEMICAL COMPANY, LATHROP FACILITY, LATHROP, SAN <br />JOAQUIN COUNTY <br /> <br />Central Valley Regional Water Quality Control Board (Central Valley Water Board) staff <br />reviewed the Shallow Injection Well installation Work Plan (Workplan), dated <br />15 February 2022, for the Glenn Springs Holdings (GSH) Company (former Occidental <br />Chemical Company), Lathrop Facility, located at 16777 Howland Road in Lathrop, San <br />Joaquin County (Site). Arcadis U.S., Inc. (Arcadis) of Roseville, California submitted the <br />Workplan on behalf of GSH by. <br /> <br />The Workplan proposes to install two shallow injection wells to provide additional <br />injection capacity to meet the target extraction volume for the Site’s ongoing <br />groundwater extraction and treatment system (GETS) remediation. Groundwater <br />treatment and injection of treated groundwater are regulated in accordance with the <br />4 March 2021 Waste Discharge Requirements (WDR) Order R5-2021-0011. Under the <br />WDR, GSH can inject a maximum of 1,350 gallon per minute (gpm) into the aquifer <br />below the Corcoran Clay and 1,250 gpm into the aquifer above the Corcoran Clay. The <br />remediation system is currently limited to a total flow of approximately 600 gpm due to <br />treated water injection capacity restraints, which is below the amount allowed in the <br />WDR. The limitation is partly due to decreased capacity due to injection well failure and <br />declining injection capacities in operational injection wells. Therefore, GSH concludes <br />that additional injection capacity is necessary. GSH proposes to install two shallow <br />injection wells, IW-5 and IW-6, at approximately 235 feet below ground surface in the <br />aquifer above the confining layer of Corcoran Clay. <br /> <br />Central Valley Water Board staff concurs with installing the proposed injection wells. <br />Please note, GSH must meet and maintain the required discharge limitations in the <br />shallow aquifer specified in the WDR. In addition, GSH must also meet the monitoring <br />and reporting requirements listed in MRP No. R5-2021-011.