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Vapor Intrusion Assessment Work Plan Project number:60653972 5.2.5 Completeness Completeness is defined as the percentage of valid measurements to planned measurements.Valid data are values that are not rejected for any reason, including deviations from QC requirements.An objective of the sampling program is to establish the quantity of data needed to support the investigation. This objective will be achieved by obtaining samples for the types of analyses required at each individual location;a sufficient volume of sample material to complete the analyses; samples that represent possible contaminant situations under investigation; and samples at critical data locations, such as background and control samples. Completeness will take into consideration adverse environmental conditions and the potential for justifiable change with respect to schedule and sample locations.The completeness goal for this project is 90 percent. 5.3 Quality Control Samples and Procedures 5.3.1 QC Checks The QC checks of both field and laboratory sample analysis will be used to assess and document data quality and to identify discrepancies in the measurement process that need correction. Field QC samples may consist of field replicates(duplicates),trip blanks, and temperature blank samples. Laboratory QC may consist of method calibration,LCS,method blanks, surrogate spikes,and MS/MSD samples.The analytical laboratory shall also report any QC failures, such as calibration check samples that exceed control limits. 5.3.2 Field Replicates (Or Duplicates) Field replicates(or duplicates)will be collected at selected locations to evaluate the environmental variability and precision at a location.Appropriate sample containers will be filled to yield an appropriate sample volume for each type of analysis to be conducted by the laboratory.The field replicates will be handled and analyzed in the same manner as the other environmental samples. Field replicates (duplicates)will be collected and submitted for analysis.AECOM will collect up to four duplicate pairs of soil gas samples(in SUMMA Canisters)for analysis by USEPA TO-15 SIM for confirmation and comparison QA/QC. 5.3.3 Method Calibration An initial calibration must be performed at the method specified frequency. The continuing calibration shall be performed at a minimum of once daily, or if the instrument exceeds calibration limits. Calibration for each target analyte will be performed,to ensure that the analytical instrumentation is functioning within the established sensitivity range.Target analytes must be present in the initial and continuing calibrations, and these calibrations must meet the acceptance criteria specified by the respective method. Calibration standards and solutions will be of known concentration and purity to achieve the criteria necessary for validation of the analytical results. Standards used in this program will be prepared and maintained under the normal laboratory standards tracking system,which ensures preparation, checking,documentation, storage, and disposal of standards according to method-specified procedures and schedules. Field equipment will be calibrated according to the manufacturer's schedule or, at a minimum,prior to use in the field. 5.3.4 Laboratory Method Blanks A laboratory method blank sample analysis will be performed by the laboratory daily or per analytical batch,whichever is more frequent. The laboratory blank undergoes the entire sample preparation and analysis process to demonstrate that the laboratory/instrument is clear of background contamination and operating at acceptable detection limits. Prepared for: California Regional Water Quality Control Board,Central Valley Region AECOM