Proposed Portland Cement MACT Rule Amendments and Performance Specifications for Mercury CEMS

U.S. EPA is proposing to amend the National Emission Standard for Hazardous Air Pollutants (NESHAP) rule that established Maximum Achievable Control Technology (MACT) for the Portland cement (PC) manufacturing industry.  These regulations are codified at 40 CFR Part 63, Subpart LLL and are referred to as the PC MACT rules.  The proposed amendments, published on May 6, 2009, will affect both major and area PC MACT sources.  Included are proposed new limits for particulate matter, mercury, and total hydrocarbons (THC) from major and area HAP sources, and hydrochloric acid (HCl) limits for major HAP sources only.  An important note for other MACT source categories is the inclusion in the proposal of performance specifications for the use of mercury continuous emission monitors (CEMS).  Amendments and additions to Appendix B of 40 CFR Part 60 that address the mercury CEMS are part of the proposed rulemaking package.

The proposed new PC MACT particulate matter standards for cement kilns are based on the tons of clinker produced rather than the kiln system dry feed rate as currently promulgated, and are established at 0.085 lb/ton for existing cement kilns and 0.080 lb/ton for new kilns.  The mercury limits are also based on clinker production but are specified as 30-day averages.  The proposed mercury limit for existing kilns is 43 lb/million tons of clinker produced and the proposed limit for new kilns is 14 lb/million tons of clinker produced.  The proposed THC limits are concentration-based and are also specified as 30-day averages with the existing kiln limit set at 7 ppmv and the new kiln limit set at 6 ppmv.  While all of these limits would apply to kilns at both major and area HAP sources, the proposed new HCl limit would only apply to kilns at major HAP sources. The proposed HCl limits are also specified as 30-day averages and are set at 2 ppmv for existing sources and 0.1 ppmv for new sources.

In addition to the new limits for cement kilns, the proposed amendments include new limits for clinker coolers and raw material dryers.  New particulate matter limits identical to the kiln limits are proposed for clinker coolers: 0.085 lb/ton for existing coolers and 0.080 lb/ton for new coolers.  Note that these limits would also be based on clinker produced rather than on the kiln system dry feed rate as for the current limits.  For raw material dryers, new THC limits are specified for both major and area sources.

In addition to the proposed new emission limits for each of the identified PC MACT sources, the proposed rule includes new performance testing and monitoring requirements.  As noted above, many of the new limits are now production-based.  The proposed rule will require that permanent weigh scale systems be installed to directly measure clinker production rates.  As a result of the proposed new mercury limits, the ban on the use of fly ash from utility boilers that is included in the current rule will also be eliminated.

The compliance date for the new PC MACT limits for existing sources would be three years from the effective date that the proposed amendments become final, which U.S. EPA envisions as sometime in 2013.  Compliance dates for new sources are tied to the effective date of the final amendments.  Note that the requirement to install a weigh scale system for measuring clinker production at existing kilns would be effective 30 days following the effective date of the final rule.  U.S. EPA is accepting comments for a 60-day period that ends July 6, 2009. The Portland Cement Association and other groups are actively involved in this rulemaking process.  However, given the stringency of some of the proposed new limits, regulated facilities would be wise to evaluate the potential impact of the revised PC MACT Rule on their existing operations and take the opportunity to comment on the proposal.  Details can be found on U.S. EPA’s website at http://www.epa.gov/ttn/oarpg/new.html.