Kimble stated that it had conducted an investigation into the cause of the excess opacity levels and determined that a faulty electrostatic precipitator (ESP) was likely the cause. Kimble had the ESP repaired and, by a Section 114 request by U.S. EPA, conducted a particulate matter (PM) stack test to verify compliance with both the visual emissions limit and the PM emissions limit. The stack test indicated compliance with both limitations. However, based on historical repair records, the operating performance of KimbleÂs ESP has been poor. As a result, Kimble has agreed to monitor stack opacity levels via a continuous opacity monitor (COMS) coincident with ESP performance parameters to insure long-term compliance with the visual emission limit.