Performance Evaluations of TCEQ Automated Gas Chromatograph (AutoGC) Monitors
In working to ensure that the TCEQ’s ambient monitoring network is performing properly, the agency will routinely conduct performance evaluations of the monitors throughout a calendar year. These performance evaluations normally follow a prescribed Quality Assurance Project Plan, which details the quality-assurance procedures, quality-control activities, and other technical activities that are implemented for a specific program. In general, the agency will conduct these performance evaluations twice a year for each of its AutoGC monitors. Additionally, if there are contractors operating the AutoGC monitors for the TCEQ, the agency may request that the contractors conduct a separate performance evaluation of the monitors. Both the agency’s and the contractor’s evaluations consist of introducing control samples that contain a variety of compounds prepared from known chemical standards. As part of the performance evaluation, the standards are different from the standards used to calibrate the monitors on a daily basis. The results from the performance evaluation are then used to identify any potential instrument, operation, or validation issues.
In April 2010, two new AutoGC monitors started collecting sampling data, one in the city of Dish and the other in the area of Eagle Mountain Lake. The TCEQ conducted a statewide performance evaluation beginning in May 2010 that included the Dish and Eagle Mountain Lake monitors for the first time.
Since the University of Texas Center for Energy and Environmental Resources (CEER) has contracted with the agency to operate the DISH and Eagle Mountain Lake AutoGC monitors, CEER—along with its subcontractor—was requested to conduct an independent performance evaluation of the two monitors.
Finally, the U.S. Environmental Protection Agency (EPA) conducted a technical-systems analysis of the TCEQ’s Air Monitoring Program during the month of September 2010. As part of this TSA visit, the EPA also conducted an audit of the DISH AutoGC monitoring station.