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Delineation and Destruction Work Plan for Well B-1 In January 2017, DTSC issued a Groundwater Audit Inspection Report for the site, listing specific action items, including securing the wells and extraction system, training site employees, delineating the nature and extent of the oily substance at well B-1, and destroying well B-1 in accordance with the County Well Standards (EHD 2005). Dudek responded to DTSC on June 5, 2017. This delineation and destruction work plan includes procedures for contaminant delineation and well destruction per DTSC's request(Dudek 2017a). 2.2 Evaluation of Nearby Wells Well B-1 is screened from 46 to 56 feet bgs. Typical groundwater flow direction at the site is toward the center of the site while the groundwater extraction system is operating. From the perspective of well B-1, this pulls groundwater northeast toward the extraction wells and away from well CSW-77, which is a California Water Service well approximately 600 feet west- southwest of well B-1. When the treatment system is not operating, groundwater flow in the shallow zone can be toward the west or east (Dudek 2017b). Dudek reviewed historical data from the three wells closest to well B-1 (wells KS-5, KS-8, and SMW-6). Benzene, toluene, ethylbenzene, and xylenes (BTEX) are typically associated with petroleum hydrocarbon contamination and are also included in the standard suite of VOC analytes. Thus, although BTEX was not reported for the Kearney samples, Dudek was able to obtain the results from the laboratory; therefore, Dudek was able to use historical VOC data to screen for BTEX.BTEX were not detected at or above laboratory method detection limits in these three wells during sampling events from the fourth quarter of 2013 through the fourth quarter of 2015 (Dudek 2014, 2015, 2016). 2.3 May 2017 Groundwater Sampling Results Dudek collected a groundwater sample from well B-1 on May 10, 2017. This was the first groundwater sample collected from well B-1 since 2012. Field personnel did not observe fuel-type odors while sampling, although the groundwater did appear to be cloudy.No evidence of oil or an oily sheen was observed in well B-1 at the time of sampling.All VOCs,including BTEX(analyzed per U.S. Environmental Protection Agency (EPA) Method 8260B), were below their respective laboratory detection limits. 1,4-Dioxane (analyzed per EPA Method 8270C) was detected above the laboratory detection limit but below the reporting limit;the estimated(J-flagged)concentration was 0.16 µg/L. The sample was later (after the hold time) analyzed for petroleum hydrocarbons per EPA Method 8015M. Diesel-range organics (C 10—C28) were detected at a concentration of 1.7 milligrams per liter, and oil-range organics (C29—C40)were detected at a concentration of 1.6 milligrams per liter(Test America 2017). 10886-7 DUDEK 4 January 2019