2022-02-09_PERMIT FILE - M2021046 (6)

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DGM Environmental Monitoring QAPP potassium chloride by an analytical laboratory or obtained from a commercial source. Results are deemed acceptable when the RPD between the known value and the measured value is less than +/- 10% for conductivity greater than 500 pmho and less than +/- 20% for conductivity less than 500 pmho. 9.1.1.3 Field Duplicates — Sampling Procedure Repeatability and Precision A field duplicate sample is a separate sample collected at the same time and location as the original sample to which it is compared. Field duplicates are collected and analyzed to provide an assessment of sample collection consistency and associated sample result variability. At least one field duplicate of a sample type should be collected by the Sample Technician during each sampling episode or for each twenty samples collected. For example, in the case of DGM baseline determination sampling, one field duplicate would be collected during the quarterly groundwater sampling of less than twenty sample locations unless specified otherwise. 9.1.2 Quality Assurance Indicators of Analytical Laboratory Performance 9.1.2.1 Unknown Samples A standard solution may be submitted by the QAO to the analytical laboratory as an unknown or in place of a routine sample. The reported analytical result can provide a qualitative indicator of acceptable laboratory performance. 9.1.2.2 Independent Performance Evaluations The results of a laboratory's participation in subscribed independent proficiency testing and inter-laboratory exchange performance evaluation programs should provide qualitative indications of acceptable laboratory performance for a wide range of analytes. The third party laboratory should be willing to provide their performance evaluation results for inspection by DGM personnel or their agents upon request. 9.2 Quality Control Indicators — Measurement Performance Criteria QC indicators are determined, prepared, monitored, and reported by the third party laboratory performing and reporting analytical results. These data quality indicators or measurement performance criteria provide objective measurement of the sensitivity, accuracy, and precision to provide an indication of the reliability of the analytical results to which they are applied. They may include instrument detection limits, lower limit of detection, method detection limit and minimum detectable activity 9.3 Quality Control of Analytical Results - Accuracy/Bias Samples According to the EPA IDQTF UFP-QAPP Manual: "Accuracy is the degree of agreement between an observed value and an accepted reference value. Bias describes the systemic or persistent distortion associated with a measurement system." Page 17