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Section 1.0 Quality Assurance Objectives The primary objective for a sampling plan is to collect samples that will allow measurements of chemical properties of a waste that are both accurate and precise. If the chemical measurements are sufficiently accurate and precise, they will be considered reliable estimates of the chemical properties of that waste. The goal of the Gettler-Ryan Sampling Plan is to produce field sampling data that are accurate, precise, complete, and comparable. Accuracy is a measure of the relative percent difference (% RPD) between a measured value and the "true" or accepted reference value. The objective for accuracy of field sampling measurements is to achieve and maintain factory equipment specifications on field instrumentation. Field measurements cannot be assessed for accuracy by spiking a field sample with the analytical parameter and measuring a response; therefore, these instruments can only be assessed for accuracy by the response to a known sample (such as a calibration standard) used to standardize it. A copy of the Gettler-Ryan Equipment Calibration Sheet can be found in Appendix A. The pH meter and conductivity meters are calibrated with reference solutions which are traceable to a reference, such as the National Institute of Standards and Technology (NIST) or Environmental Protection Agency (EPA) reference materials. Precision is the agreement between a set of replicate measurements without assumption of knowledge of the true value. The objective for precision of field data collection methods is to take replicate (two or three) measurements for field parameters to determine the reproducibility of these measurements. For the pH meter, precision will be tested by multiple readings in the medium of concern. Consecutive readings should agree within plus or minus 0.1 pH unit. The thermometer will, be visually inspected before each use. Consecutive measurements should agree within plus or minus 1 degree Celsius. Conductivity meters are tested by placing the sample electrode in potassium chloride buffer solutions of 100, 1000, or 10,000 umhos/cm. Consecutive readings should agree within ±5%. Comparability expresses the degree of confidence with which one data set can be compared to another. The comparability of all data collected is ensured by: 1 ) using identified standard methods for both sampling and analysis phases of this project; 2) ensuring traceability of all analytical standards and/or source materials to EPA or NIST standard references, and 3) using standard reporting units and formats including the reporting of QC data. Completeness is defined as the percentage of measurements made which are judged to be valid. The QC objective for completeness is the generation of valid data for at