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Cleanup in Vulnerable Communities'Initiative Discovery Project Reference:Favorite Cleaners and Enforcement Discovery Investigation Work Plan Project Number:60688620 4.3 Data Collection and Evaluation The AECOM QA Manager or her/his designee, will review the laboratory reports and prepare a data-review verification sheet that will be appended to the Discovery Investigation report. The laboratory reports will be reviewed for the following: • Data completeness, • Chain-of-custody, • Holding times, • Sample preservation, • Blanks, • Laboratory control samples, • MSs/MSDs, • Surrogates/internal standards(as applicable), and • Field QC samples. Data that do not meet the DQOs set forth in Section 4.2 above will be qualified and flagged. Data qualification flags will indicate whether results are considered anomalous, estimated, or rejected. Only rejected data are considered unusable for decision-making purposes; however, other qualified data may require further verification, such as reviewing the laboratory's raw data in accordance with USEPA's Guidance on Environmental Data Verification and Data Validation(USEPA 2015c). Detection limits associated with the analytical data will be reviewed before eliminating chemicals from the human health screening evaluation because they were not detected. In some cases,the detection limit for a chemical may be greater than the corresponding standards, criteria,or concentrations derived from toxicity reference values; therefore, the chemical may be present at levels greater than these corresponding reference concentrations, which may result in undetected risk. In other cases, a particular detection limit may be significantly higher than positively detected values in other samples in a data set.After considering these cases and any other reasonable reasons why contaminants may not have been detected, chemicals that have not been detected in any medium will be eliminated if appropriate. If information exists to indicate that the chemicals are present,they will not be eliminated.The Report will identify the possibility of undetected or non-sufficiently characterized contaminants and recommend additional sampling as part of further investigation, as appropriate. A laboratory may identify VOC and semi-volatile organic compound tentatively identified compounds(TICS)during sample analysis. Both the identity and reported concentration of a TIC are not definitive. Depending on the relative number of TICS compared to non-TICs,options exist to address TICS during the screening evaluation(USEPA 1989). If a significant number of TICS are identified during the investigation,the use of these data in the human health screening evaluation will be discussed with DTSC. For analytical results,various qualifiers pertaining to the quality of the data may be assigned to certain analytical results by either the laboratory conducting the analysis or by persons conducting data review as discussed above. For example, some results may be marked as estimated if the concentration is below the verifiable or contract- required detection limit but may be detected at a lower value by the instrument.All qualified results will be reviewed prior to use of the chemical data set for the human health screening evaluation.Any data discrepancies will be reviewed and explained in the Discovery Investigation report. If enough data are rejected as unusable for decision- making purposes, such that the DQO for completeness is not achieved,then corrective actions such as reanalysis or resampling will be performed,with DTSC concurrence(USEPA 2004). 4.4 Data Management The AECOM Project Manager will review the field notes,field forms(such as boring logs), and chain-of-custody forms to evaluate completeness of the field records, appropriateness of the field methods employed, and whether the chain- of-custody forms were completed correctly.When the laboratory reports are submitted to AECOM, an independent reviewer will prepare a data verification checklist. Subsequently, the data will be entered onto tables to be included in Prepared for: California Department of Toxic Substances Control AECOM 29