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4.2.2 Soil Matrix Sampling Table 2 presents a summary of the soil matrix sampling and analyses planned for this PEA. As directed in the DTSC scope of work, soil matrix samples will be obtained from all 21 soil gas probe locations at a depth interval of 0 to 0.5-foot bgs for surface soil characterization, then at 4 to 5 feet bgs to check for deeper contamination. In addition, at the six specific areas of concern, soil matrix samples will be obtained at a depth interval of 14 to 15 feet bgs. All soil samples will be analyzed by USEPA-approved methods for Title 22 total metals, semi-volatile organic compounds (SVOCs) (including PAHs), organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and total petroleum hydrocarbons (TPHs). The analysis of TPHs will include carbon chain distinction(C8 through C40)to check for gas-,diesel-,and heavy carbon chain ranges of TPHs. If VOCs are detected by the soil gas investigation, additional soil matrix samples (up to a total of 12 samples) will be collected from the corresponding locations and depths using the USEPA Method 5035 sampling and field-preservation method. These samples will be analyzed for VOCs using USEPA Method 8260B. If soil samples are collected for VOC analysis, enough sample will be collected to allow determination of the moisture content as well. To provide required data for the human health and ecological hazard screening conducted as part of the PEA, two soil samples will be analyzed for physical parameters including soil moisture content, total porosity, bulk density, grain-size distribution, pH, TOC, and effective permeability. These samples will be collected from the continuously-cored boring at 5 feet bgs and at 15 feet bgs or at the interval of a significant change in soil lithology within the first 15 feet bgs. In addition to the planned samples, if areas significantly stained with waste oil or other petroleum products or organic constituents are observed, URS will recommend to DTSC additional soil sampling, and will proceed as directed by DTSC. Recommended analyses for such samples would include SVOCs, TPH and lower detection limit analysis for polynuclear aromatic hydrocarbons (PAHs) by EPA method 8310. Recommended sampling intervals would likely be at 0 to 0.5-foot and 2 to 3 feet bgs. The sampling protocol for the soil matrix samples is discussed in Section 4.2.4. Appropriate quality control samples including equipment rinsate blanks and field duplicates will be collected in accordance with the PEA Guidance Manual specifications. No background soil samples will be collected, as DTSC will provide background data from a similar nearby site. 4.2.3 Water Sampling Table 3 presents a summary of the water matrix sampling and analyses planned for this PEA. The only water samples anticipated are equipment rinsate blanks discussed in a later section of this work plan. No groundwater samples are currently planned under this PEA as groundwater is reportedly first encountered at greater than 110 feet bgs in the Site vicinity. Should perched groundwater be encountered during the drilling operations, groundwater sampling will be attempted using the Hydropunch technique (or equivalent) in order to provide screening-level data. Water samples will be analyzed by USEPA- approved methods for Title 22 metals, VOCs, SVOCs (including PAHs), OCPs, PCBs, and TPHs. Regarding metals analyses,equipment rinsate blanks will be analyzed for total metals, while groundwater samples, if collected, will be analyzed for dissolved metals. The groundwater samples will also be field tested at the time of collection for turbidity, pH, temperature, and specific conductivity by properly calibrated instruments. To provide for the possibility of groundwater sampling, protocol has been included in a later portion of this sampling plan. Page 15 PAPEA Lockeford\Work PlanULockeford WP.doc