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DGM Environmental Monitoring QAPP <br /> Section 9 DATA QUALITY INDICATORS AND ASSESSMENT <br /> Data quality indicators reflect the quality of measurement data. Evaluation of this quality <br /> is based on evaluation of those indicators addressed throughout this and other sections <br /> of this QAPP. These indicators vary from more subjective QA indicators to distinctly <br /> objective and measurable QC indictors. There is some overlap of these characteristics <br /> among the various data quality indicators. <br /> 9.1 Quality Assurance Indicators <br /> Some data quality indicators do not lend to objective measurement but are used to <br /> provide subjective indications of data quality, these are referred to as QA indicators and <br /> are used to assure sample and analytical data quality and usability. Various blank, <br /> blind, and other samples are utilized for QAe purposes. Some monitor field variables, <br /> others are designed to monitor procedural variables, and others provide indication of <br /> laboratory data quality. The sample type and sampling procedure determine which QA <br /> indicator sample is appropriate and required. These samples are monitored for trends <br /> or anomalies. <br /> 9.1.1 Quality Assurance Indicators of Field Sampling Performance <br /> QA field samples are QA samples taken to investigate possible contamination or <br /> anomalies resulting from field sampling practices or field conditions. <br /> 9.1.1.1 Equipment Blank— Sampling Equipment Decontamination Effectiveness <br /> On the day that water sampling is conducted, an equipment blank is collected to insure <br /> that non-dedicated sampling devices and filtration equipment have been cleaned <br /> effectively. This is accomplished by flushing ASTM Type II reagent grade water through <br /> the sampling and filtration equipment and collecting a sample of the water in an <br /> appropriate sample container. This sample is collected after the sampling equipment <br /> has been decontaminated preferably after sampling a location known to have relatively <br /> high levels of constituents of concern or contaminants. The sample is submitted to the <br /> laboratory for analysis like any other sample. <br /> 9.1.1.2 Blind Samples - Field Parameter Measurement Verification <br /> The validity of the field parameter measurements of pH and conductivity may be <br /> verified using blind samples on a non-scheduled basis. <br /> • A blind sample may be submitted by the QAO to the Sample Technician for field <br /> pH determination. The blind sample may be a pH buffer standard or a pH <br /> sample obtained from a reliable source such as EPA or a commercial vendor. <br /> An acceptable pH measurement will be either +/- 0.2 pH units or 2 standard <br /> deviations from the known value, whichever is most restrictive. <br /> • A blind sample may be submitted by the QAO to the Sample Technician for <br /> specific conductance determination. This sample may be prepared from stock <br /> Page 16 <br />