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2.74 mg/kg to 6.71 mg/kg. Lead results in the remaining confirmation samples ranged from 8.48 mg/kg to 25.3 mg/kg. Based on the comparison of the data to the screening criteria, there were no exceedances. As such, the excavation area was backfilled and construction for the SPCC Containment Structure was initiated. As part of the excavation operations at the Site for the SPCC Containment Structure, 387.10 tons of material, impacted with MGP-related contaminants, was removed, transported and disposed at the Waste Management Altamont Facility located at 10840 Altamont Pass Road in Livermore, California. The letter report entitled Final Summary Report for the Oversight of Excavation Operations for the Removal of Impacted Soil- Spill Prevention Control and Countermeasure (SPCC) Containment Structure at the PG&E Tracy Service Center [Formerly the Tracy Manufactured Gas Plant (MGP)] Site, Tracy, California, which documents the removal of MGP impacted materials associated with the construction of the SPCC Containment Structure is provided in Appendix N1. On February 11, 2009, the DTSC provided a no further action (NFA) letter for the area associated with the SPCC structure (Appendix N2). As such, future remedial action documents will not include the SPCC area. 4.6 DATA QUALITY Data generated during this RI/SSI complied with the QAPP presented in the DTSC-approved April 2008 Workplan (Parsons, 2008). The QAPP addresses the organization, objectives, functional activities, and specific QA/QC activities associated with the collection of environmental data during the implementation of RI/SSI work. Together with the April 2008 Workplan, the QAPP presents the plan for sampling and analysis as part of the RI/SSI to be performed under the direction of the DTSC. The purpose of the QAPP is to identify the methods to be employed to establish technical accuracy, precision, and validity of data that is generated during the RI/SSI. The QAPP contains general information and specific details regarding field sampling, laboratory, and analytical procedures that apply to activities described in the April 2008 Workplan (Parsons, 2008) and the Final Technical Memorandum (Parsons, 2009). It provides field and laboratory personnel with instructions regarding activities to be performed before, during and after field investigations. These instructions insure that data collected for use in project decisions will be of the type and quality needed for their intended purpose. 4.6.1 Data Validation As part of the QA/QC processes for developing technically accurate, precise, and valid data, a senior chemist from Parsons reviewed the data generated for the RI/SSI. The laboratory analytical results were assessed to evaluate the quality of the laboratory tests. As part of the QA/QC requirements for this project, a detailed Level II data validation report was prepared for data collected during this remediation. Level II data validation was performed on approximately 10% of the data, and the report is provided in Appendix O. Based on the Level II QA/QC data validation performed on 10% of the samples collected at the for the RI/SSI at the Former Tracy MGP Site, results are considered accurate, precise, complete and representative of conditions that currently exist at the Site. Additionally, these results are sufficient for their intended use. PARSONS 43 FINAL RI REPORT-FORMER TRACY MGP APRIL 2010