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• Monitor the performance of the various measurement systems being used in the program to maintain statistical control and provide rapid feedback, so that corrective measures, if needed, can be taken before data quality is compromised; • Periodically assess the performance of these measurement systems and their components; and • Verify that reported data are sufficiently complete, comparable, representative, unbiased, and precise, so they are suitable for their intended use. The purpose of the sampling is to evaluate the nature and extent of impacts in the unsaturated soil, groundwater, and soil gas in specific areas of the Site. 4.0 SAMPLING AND ANALYTICAL PROGRAM This sampling and analytical program was developed to obtain adequate data to characterize impacts to soil, indoor air, soil gas, and groundwater. Groundwater monitoring wells will be installed to initially define the lateral extent of the PCE plume. Indoor air sampling and sub-slab soil gas sampling will be conducted to assess potential exposures to commercial workers. A soil gas assessment will be conducted to evaluate the potential of elevated concentrations of VOCs either being released from the sewer lateral or migrating to residential areas south of the Site. Grab water samples and soil samples will be collected from the inferred location of the petroleum hydrocarbon release and soil samples will also be collected to assess for the potential presence of environmentally persistent pesticides. 4.1 Sample Selection and Analytical Criteria Generally, there are six, in some cases overlapping, areas that are proposed for Site characterization. Four of these areas, or tasks, include the installation and monitoring of groundwater monitoring wells associated with the release of PCE from the Quality Cleaners, indoor air and sub-slab soil gas sampling, sampling shallow soil gas at the exterior of the dry cleaners suite and along the sewer lateral, The remaining areas, or tasks, are associated with the 1991 petroleum hydrocarbon release and the assessment of environmentally persistent pesticides. Soil gas samples will be collected from sub-slab probes and shallow exterior soil gas probes to assess VI within selected tenant suites and adjacent residential areas, respectively. Additional soil gas probes will be installed and sampled along the alignment of the sewer lateral to assess the potential of a release of PCE from the lateral. Indoor air samples (with attendant outdoor air sample) within selected tenant suites will also be used to assess VI within selected tenant suites. The water table is shallow and is expected to be encountered at approximately 10 feet bgs and therefore, the number of soil samples that will be collected for laboratory analysis will be limited by the relatively thin unsaturated zone. It is possible that the depth to the water table may be deeper than 10 feet given the lack of recharge that is occurring due to the fourth year of drought. Selected soil borings associated with the assessment of the petroleum hydrocarbon release, the groundwater monitoring wells, and pesticide residue will be continuously cored to allow a detailed evaluation of the Site stratigraphy. Sampling and Analysis Plan Tracy Corners Shopping Center 3225 North Tracy Boulevard Tracy,California 95376 Partner Project Number SM14-129814 Docket Number HAS-VCA 14/15-108 August 15,2016 Page 10