Ameren Missouri owns and operates the North SO2 monitoring site near its Labadie Energy Center, but the Missouri Department of Natural Resources provides quality assurance. Environmental specialists with the department conduct periodic on-site performance audits, just as they do at state-operated sites that monitor SO2. Ameren is operating the North site and other sites under a quality assurance project plan (QAPP) approved by the department.
Working with the department, Ameren Missouri established the site in January 2017. It joined three other sites established in the vicinity of Ameren Missouri in Labadie because of EPA's Data Requirements Rule (DRR). It gave the state two choices for characterizing air quality in areas with large sources of SO2 emissions: modeling or ambient air monitoring. In consultation with Ameren, the department chose air monitoring. The rule covers the third and fourth steps toward implementation of the 2010 SO2 standard of 75 parts per billion. Industry and department personnel used EPA guidelines to pick the monitoring sites; for example, they had to verify that the monitors are appropriate distances from trees, buildings and minor sources of SO2.
Data from monitors and audits will be part of EPA's Air Quality System. The federal agency will use the data collected over an initial three-year period to determine compliance with the one-hour SO2 standard.