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Title: Sampling and Analysis Plan for Environmental Control Number: Revision Date: Page 15 of 23 Groundwater Monitoring PUE.EN.D.026.03 1 10/18/2019 Two types of data qualifiers are recognized for environmental samples, including: 1) flags placed on results by the laboratory to denote problems with associated blanks, spikes, etc. (i.e., laboratory flags), and 2)flags placed by data validation personnel to denote problems or issues associated with sample collection, site conditions or documentation (i.e., validation flags). Documentation Reviews Samples are analyzed within the required holding time limits specified in the analytical method or the appropriate reference. Samples are preserved in accordance with applicable method specifications. Samples not analyzed within specified holding time limits, and/or not appropriately preserved, are invalidated unless professional judgment dictates that flagging would be more appropriate (e.g., consistent with historic observations). Field QA Sample Review The preparation of an equipment rinsate blank is required when sampling groundwater with reusable sampling equipment. However,use of a water level measuring probe decontaminated in accordance with Section 3.5 will not in and of itself trigger the requirement for a field rinsate blank. Flagging is not required when fewer field blanks than required are collected, but a QA memo will be included with the data. However, sample results associated with contaminated equipment rinsate blanks (i.e., samples collected prior to the equipment blank's preparation) are flagged if the sample blank concentration exceeds 10% of the sample concentration. Further, sample results may be invalidated if the blank concentration exceeds 50% of the sample concentration (subject to professional judgment). Data are not flagged if the sample concentration is below the reporting limit, regardless of the blank concentration, because the sample is not cross-contaminated. Sample concentrations are not corrected by subtracting blank concentrations. Field duplicates are samples intended to assess variations due to sample collection, handling or analysis. It is recognized that natural variations in the environment can cause variations in concentrations. Field duplicate concentrations should agree with one another as described below: Relative Concentration Relationship Criterion Concentrations < 5 Times the Reporting Limit Reporting Limit Concentrations > 5 Times the Reporting Limit RPD (± 50% for metals, 20% for other analytes) The RPD (Relative Percent Difference) is calculated with the following equation: RPD (%) = (S 1-S2)/[(S 1+S2)/2] * 100 where: S 1 and S2 are the two duplicated values or the highest and lowest values if more than two sample duplicates are analyzed.