Metals Monitoring: In 1996 Performance Specification 10 (PDF)(11 pp, 43 K, April 1996) was proposed in conjunction with the original Hazardous Waste Combustor NESHAP, but because the measurement technology had not been fully developed and demonstrated, the specification was not promulgated. More recently, EPA has evaluated, at several facilities, a commercial version of an x-ray fluorescence metals CEMS capable of measuring most of the MACT hazardous metals in nearly real time (the instrument was built by a small business instrument developer, Cooper Environmental). Eli Lilly Company received approval from the EPA to use this instrument as a CEMS as an alternative in lieu of parameter monitoring on a hazardous waste incinerator. Lilly invested in much laboratory and field work to prove to the EPA that their CEMS is accurate, reliable, and verifiable. The US Army has successfully installed and evaluated one of these CEMS on a hazardous waste incinerator. These studies resulted in several monitoring methods and performance standards for the x-ray technology. These documents may be found under the Other Methods section of this web site.

The EMC is presently evaluating ambient fence line multimetals monitoring for compliance determination, ambient health exposure studies, and for locating and evaluating unknown sources of metals emissions. The knowledge gained from, and the success of, the Lilly study has provided support in the transition to a study of the fence line monitoring platform of this x-ray fluorescence technology. A stakeholder group has been formed to provide feedback to EMC on the project. A validation field study is underway in Missouri to compare the fence line monitor to existing PM-10 ambient monitors.

Mercury Monitoring: Like Performance Specification 10, Performance Specification 12 for mercury (Hg) CEMS was also proposed in conjunction with the original Hazardous Waste Combustor NESHAP, but because the measurement technology was not fully developed nor demonstrated at that time, it was never promulgated. Between 2003 and 2005, Performance Specification 12A for Hg CEMS was proposed and promulgated in conjunction with the Clean Air Mercury Rule (CAMR) after extensive demonstration of Hg CEMS and identification of appropriate performance parameters. In 2007, CAMR was vacated by the DC Circuit Court, which called into question the legality of using Performance Specification 12A. It has since been re-proposed in conjunction with amendments to the Portland Cement NESHAP.

In order to obtain high quality mercury monitoring data, it is necessary to have Hg calibration gas standards of known concentration and known uncertainty. EPA's Clean Air Markets Division, working with EPA's Office of Research and Development and EMC, have recently completed two interim EPA traceability protocols to establish procedures for the qualification and certification of elemental and oxidized Hg gas generators.