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Sulfolane Remedial <br /> Investigation Work Plan <br /> ARCADIS Former Occidental Chemical Corporation <br /> ' Lathrop, California <br /> 4.2.3 Sulfolane Shallow Groundwater Delineation <br /> ' To evaluate the lateral and vertical extent of sulfolane impacts in shallow groundwater <br /> beneath the Site, approximately sixteen(16)direct-push borings will be advanced to <br /> approximately 70 feet bgs. In'addition, as many as four direct-push borings will be <br /> advanced to approximately 90 feet bgs pending the results of the 16 groundwater <br /> samples collected at 70 feet bgs. Proposed groundwater investigation boring locations <br /> ' are detailed on Figure 5. <br /> Three to four discrete groundwater samples will be collected from each boring using <br /> ' Hydropunch®groundwater sampling methodology. Groundwater samples will be <br /> collected from approximately 5 feet into the water table(approximately 20 feet bgs), 35 <br /> feet bgs, 70 feet bgs,and/or 90 feet bgs,where applicable,and analyzed for sulfolane <br /> by APPL by APPL SOP ANASULF using a GC/MS on a standard turnaround time <br /> basis.Soil boring locations will be surveyed in the field using a handheld GPS device. <br /> The SOP for Hydropunch®groundwater sample collection provides the necessary <br /> ' equipment and sampling and documentation procedures and is included in <br /> Appendix B. <br /> ' 4.2.4 QA/QC Samples <br /> Quality control/quality assurance(QA/QC)procedures will be employed in both the <br /> field and the laboratory. Field duplicates will be collected at a rate of 1 per 10 field <br /> samples of similar matrix. Field duplicate locations will be identified to include sample <br /> locations with suspected contamination to ensure precision calculations can be <br /> ' performed. <br /> One equipment rinsate blank will be collected each field day that includes collection of <br /> samples by nondisposable(reusable)sampling equipment.The locations and depths <br /> ' of the QAIQC samples will be determined in the field. <br /> Analytical data will be validated by Conestoga-Rovers&Associates(CRA)prior to <br /> ' review by ARCADIS. <br /> Matrix spike/matrix spike duplicate analysis will be completed by APPL from primary <br /> samples collected in the field. Field documentation procedures will be kept in <br /> accordance with the ARCADIS SOPS provided in Appendix B. <br /> rmcvrixort ynn¢AlllAoc 9 <br />