In January 2017, the Doe Run Company began monitoring sulfur dioxide at three new sites in the vicinity of its Buick Resource Recovery Facility near Boss. Although Doe Run owns and operates the three sites, the Missouri Department of Natural Resources provides quality assurance. Environmental specialists with the department conduct periodic on-side performance audits, just as they do at state-operated sites. Doe Run is operating the monitors under a quality assurance project plan (QAPP) approved by the department.
According to the federal SO2 Data Requirements Rule finalized in August 2015, air agencies must characterize air quality around sources that annually emit 2,000 tons or more of SO2. The EPA gave two choices for characterization: modeling or monitoring. The department included the Doe Run facility on Missouri's list of affected facilities even though reported emissions were below 2,000 tons per year. At that time, the department was reviewing data from the facility, in part, because of uncertainty over emission figures. In consultation with Doe Run, the department chose air monitoring to meet the EPA rule, which covers the third and fourth steps toward implementation of the 2010 SO2 standard. 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 standard.
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 emissions.