ARCHIVED REPORTS_DRAFT - PHASE I REMEDIAL INVESTIGATION REPORT

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Kennedy/Jenks Consultants ' The TPHd detected in two of the soil equipment blanks is also not considered to significantly affect the findings or conclusions of the investigation. On days when TPHd was detected in the soil sample equipment blanks, TPHd was not detected at concentrations exceeding analytical ' reporting limits in many of the soil samples, indicating that cross-contamination between samples and borings was minimal or absent. TPHmo was commonly detected at greater concentration than TPHd in soil samples but TPHmo was not detected in the equipment blanks, ' further indicating that cross-contamination between samples and borings was minimal or absent. ' The zinc and nickel concentrations detected in the soil equipment blanks listed above are not considered to significantly affect the findings or conclusions of the investigation. Zinc and nickel were detected at low concentrations in only two of the soil sample equipment blanks. These metals were detected in soil samples collected on the days the blanks were collected, but were also detected at similar concentrations in samples collected on other days as well. Other metals, such as copper, were detected at greater concentrations in the soil samples than zinc and nickel yet were not detected in equipment blanks. 4.2 Data Validation and Usability This section discusses the QA activities that occurred after the data collection phase of the project. Implementation of the following actions ensured that the data conformed to the specified criteria for achieving the project objectives. 4.2.1 Data Review, Verification, and Validation ' Field and laboratory data generated during the remedial investigation were reviewed, verified, and validated. Field data entered into the database were verified. Errors identified during the verification of data were corrected prior to release of the final data. ' The laboratory was responsible for verifying analytical results prior to the submittal of the data to Kennedy/Jenks. Initially, all analytical data generated by the laboratory were verified by the ' laboratory. During the analysis process, the analyst and the laboratory QA Manager verified that the results met various performance-based control limits (e.g., surrogate recoveries and continuing calibration). Non-conformance of various method QC requirements and control limits 1 warranted the re-analysis and/or re-extraction of a sample. Once the laboratory released the data, the data were reviewed by the Kennedy/Jenks project staff. The data package was reviewed to verify that all samples were accounted for. Finally, the data were verified and validated based on the quality objectives specified in the QAPP. If data did not meet required criteria, they were flagged with data qualifiers as specified under the action portion of each requirement of the functional guidelines (EPA 1999, 2002). 4.2.2 Verification and Validation Procedures ' During implementation of the SAP, the Kennedy/Jenks was responsible for overseeing field • measurements and data recording. The laboratory forwarded chain-of-custody forms to Kennedy/Jenks upon receipt of samples. The chain-of-custody forms were reviewed by DRAFT Phase I Remedial Investigation Report Page 20 ' Former Tracy Railyard, Tracy, California g:\is-group\adminljob\05\0565777.18_uprr\00-feportslri rpUeAdoc