California Association of Sanitation Agencies
Sewage Sludge Incineration
On February 23, 2011, US EPA published final regulations for Sewage Sludge Incinerators (SSI),which addressed many of the comments submitted by CASA, CASA member agencies, NACWA, and others. Also published that day were regulations defining non hazardous solid waste for combustion purposes. The solid waste definition determined that sewage sludge is a solid waste when combusted, which forced EPA to develop the new SSI rules. Under the new regulations, SSIs are subject to section 129 of the Clean Air Act rather than section 112, under which SSIs have historically been regulated. Under section 129, EPA was required to develop Maximum Achievable Control Technology (MACT) standards for nine pollutants, along with other regulatory controls. In the original proposed regulations EPA set "beyond the floor" MACT standards for mercury. This meant that mercury standards were set at significantly more stringent levels than would have been set at simply the MACT standard. Comments were submitted that EPA used flawed data to set this standard. EPA also determined that all new SSIs would be fluidized bed (FB) incinerators so did not establish New Source Performance Standards (NSPS) for multiple hearth (MH) incinerators. This would have precluded even existing MH incinerators from undergoing significant improvements in the future since this would have forced them to meet the NSPS standards for FB incinerators. CASA provided comments on both rules as did NACWA, WEF, and Central Contra Costa SD [link] and Palo Alto [link]. Both of these provisions were dropped in the final rule and along with other significant changes. EPA was forced to develop these regulations due to a court order and given the significance of the comments they received sought an extension from the court until July 15, 2011. This request was denied. Recently, it became known that some confusion was created by EPA’s response to comments in the Solid Waste Definition regarding contained gaseous fuels. The confusion could have resulted in EPA applying the Commercial and Industrial Solid Waste Incinerator (CISWI) rules to units combusting methane from anaerobic digesters. However, EPA has acknowledged that it was not its intent to change any regulatory framework for biogas as explained in the following letter.