||Source Technology Associates, Research Triangle Park, NC. ;Cadmus Group, Inc., Raleigh, NC.;Environmental Protection Agency, Washington, DC. Acid Rain Div.
The inclusion of the t-test for bias in the Acid Rain Regulations, 40 CFR Part 75, signaled a marked improvement in the capability to detect a significant source of measurement error that had previously remained hidden. The capability to detect bias left environmental technicians and instrument operators with the often daunting job of, first, diagnosing the cause of the measurement bias, and, then, taking steps to correct it. This publication is intended to make that job easier. A pull-out chart, entitled Eliminating Bias in CEMS -- A Checklist, provides a comprehensive listing of the monitoring system problems that can cause systematic error. A brief description and potential corrective actions are shown for each problem. Finally, the Checklist directs users to the appropriate pages in the accompanying Operator's Guide, where fuller descriptions of problems and remedies can be found. The accompanying Operator's Guide to Eliminating Bias in Monitoring Systems is organized into eight chapters. The problem areas covered are: Probe Location and Stratification (Chapter 2), Extractive Sampling Systems (Chapter 3), In-Situ Gas Monitoring Systems and Opacity Monitors (Chapter 4), Flow Monitors (Chapter 5), Gas Analyzers (Chapter 6), and Data Acquisition and Handling Systems (Chapter 7). Chapter 8, the last chapter in the Operator's Guide, discusses elements that should be incorporated into ongoing Quality Assurance Programs to detect and prevent the problems that produce systematic error in monitor measurements.