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groundwater samples from targeted strata. The location of these proposed borings and the <br /> details of the sampling would be included in an addendum to this workplan and submitted to the <br /> DTSC for concurrence and approval prior to the commencement of the work. <br /> Inputs to Decision: <br /> Depth and flow direction of groundwater, groundwater velocity, characteristics of soil within the <br /> upper portion of the water table, and commercial exposure scenarios. <br /> Boundaries of the Task Investigation: <br /> Geographical: The area wherein the monitoring wells will be installed extends from approximately <br /> 50 feet southwest to approximately 180 feet north-northeast of the dry cleaners suite, respectively. <br /> Temporal:This task is scheduled be conducted in July-August 2016. <br /> Decision Rule: <br /> If PCE or related degradation products of PCE in groundwater samples are detected at <br /> concentrations greater than applicable screening levels additional assessment may be warranted <br /> including, but not limited to, the installation of additional groundwater monitoring wells. In <br /> addition, if the groundwater gradient as measured in two consecutive quarters is not to the north- <br /> northeast, or if the concentrations of target VOCs are detected in either the upgradient or <br /> downgradient monitoring wells at concentrations that suggest the plume is not defined, the <br /> installation of additional groundwater monitoring wells may be warranted. <br /> 1.4.4 Petroleum Hydrocarbon Release Assessment <br /> Problem Statement: <br /> Historical data indicate that petroleum hydrocarbons, primarily diesel constituents, were possibly <br /> released in the northeastern portion of the Site. Due to the narrative and map in the 1991 County <br /> Investigation Report and the resulting uncertainty of the location of the hydrocarbon release, <br /> three additional locations will also be assessed based on pertinent Site features from the historic <br /> aerial photographs. The vertical and lateral extent of the release and the potential impacts to <br /> groundwater are not known. <br /> Sampling and Analysis Plan <br /> Tracy Corners Shopping Center <br /> 3225 North Tracy Boulevard <br /> Tracy,California 95376 <br /> Partner Project Number SM14-129814 <br /> Docket Number HAS-VCA 14/15-108 <br /> August 15,2016 <br /> Page 6 <br />