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1 Introduction <br /> 1 .1 Background and Purpose <br /> The former Kearney-KPF facility(U.S. Environmental Protection Agency(EPA) ID No. CAD981429715) is located at <br /> 1624 East Alpine Avenue in Stockton, California (site; Figure 1, Location Map). The site encompasses 12.6 acres <br /> of privately owned land located south of Alpine Avenue. Beginning in 1951, the site was developed for use in <br /> manufacturing high-voltage switching devices for utility companies in the United States and Canada. Two <br /> manufacturing processes, silver plating and galvanizing, resulted in the generation of hazardous wastes. Site <br /> assessment activities began in the late 1980s. The ponds in which waste was formerly disposed were closed in <br /> 1991. A groundwater treatment system was installed and began operating in July 1992. <br /> The treatment system was shut down in late 1998 for construction and prove-out of an enhanced groundwater <br /> treatment system to remove 1,4-dioxane from groundwater and supplement removal of other volatile organic <br /> compounds (VOCs). Extraction and treatment resumed in July 2003. Full-scale groundwater extraction and <br /> treatment at the site continued until March 2012, effectively containing groundwater contamination and reducing <br /> its mass in each of the affected subsurface zones. The treatment system was shut down from March 2012 to <br /> January 2015 to perform a rebound study. As of September 2017, when the California Department of Toxic <br /> Substances Control (DTSC) Hazardous Waste Facility Post Closure Permit (permit) was renewed, the treatment <br /> system is being pulsed in approximately 3-month periods; it is on during Q2 and Q4, and off during Q1 and Q3. <br /> Following initial site assessment, investigation, and remediation activities, monitoring and remediation at the site <br /> has been performed in accordance with the Interim Groundwater Remedial Action Plan (Hargis 1990); the DTSC <br /> permit, which was first issued in 1992; and Central Valley Regional Water Quality Control Board (CVRWQCB) <br /> Monitoring and Reporting Program (MRP)and Waste Discharge Requirements,which were first issued in 1991.The <br /> DTSC renewed the permit in 2004 and 2017 (DTSC 2017).A revised MRP and Waste Discharge Requirements(No. <br /> R5-2017-0125), which concurs with the permit, was issued by the CVRWQCB in December 2017. <br /> This report is intended to satisfy the reporting requirements of the DTSC permit and the CVRWQCB MRP Order No. <br /> R5-2017-0125 (CVRWQCB 2017a). Groundwater monitoring in 2018 was conducted in accordance with the Water <br /> Quality Sampling and Analysis Plan (WQSAP) (Dudek 2017a), which specifies standard operating procedures for <br /> groundwater monitoring and sampling. <br /> Groundwater monitoring is currently conducted on a semi-annual basis.This report discusses water level and water <br /> quality data obtained during the October 2018 annual groundwater monitoring event conducted at the site. Data <br /> obtained during the May 2018 semi-annual groundwater monitoring event(previously reported in the semi-annual <br /> report) is also summarized herein. <br /> 1 .2 Summary of Treatment System Operation <br /> Full-scale continuous operation of the on-site groundwater extraction and treatment system originally commenced <br /> on January 8, 1993.VOCs were removed from the groundwater by air stripping and carbon adsorption.The system <br /> was shut down on January 8, 1999, due to the new action level for 1,4-dioxane established by the California <br /> Department of Health Services. The treatment system was retrofitted with an ultraviolet/oxidation component to <br /> D U D E K 10886-1 <br /> 1 March 2019 <br />