U.S. EPA Releases 1-Hour NO2 NAAQS Modeling Guidance

The U.S. EPA Air Quality Modeling Group (AQMG) recently released a new guidance document for NO2 modeling.   The document outlines procedures that can be used to calculate the NO2 design values for comparison to the new 1-hour NO2 National Ambient Air Quality Standard (NAAQS).  The new 1-hour NO2 standard of 100 ppb goes into effect on April 12, 2010.  This 1-hour NO2 standard is based on the 3-year average of the 98th-percentile of the annual distribution of daily maximum 1-hour concentrations.

Right now, AERMOD, U.S. EPA’s current regulatory air quality dispersion model, can only calculate 1-hour averages.  Therefore, the guidance document describes procedures on how to manually post-process the AERMOD results to calculate the 3-year average of the 98th-percentile of the annual distribution of daily maximum 1-hour concentrations.  Additionally, the document states that AQMG is currently working on a post-processor that will automatically post-process AERMOD output files to calculate the 3-year average of the 98th-percentile of the annual distribution of daily maximum 1-hour concentrations.  This post processor should be released in the near future and will be found here.

The guidance document also outlines procedures to use when modeling with National Weather Service (NWS) data.  Since Appendix W of 40 CFR Part 51 requires the use of five (5) years of NWS meteorological data for air quality modeling evaluations, the document states that the 5-year average of the 98th-percentile of the annual distribution of daily maximum 1-hour concentrations should be calculated and compared to the new 1-hour NO2 NAAQS standard.  Specifically, the document states that “while the 1-hour NAAQS for NO2 is defined in terms of the 3-year average for monitored design value to determine attainment of the NAAQS, this definition does not preempt the Appendix W requirement for the use of 5 years of NWS data, and the 5-year average serves as an unbiased estimate of the 3-year average for purposes of modeling demonstration with the NAAQS.”

At this time, AQMG has not outlined procedures to follow when using site specific meteorological data.  When using site-specific meteorological data for air quality modeling evaluations, Appendix W of 40 CFR Part 51 only requires one (1) year of on-site meteorological data to be used.  As mentioned previously, AQMG is recommending following Appendix W of 40 CFR Part 51 guidance as an appropriate substitute for the proposed NAAQS when using NWS data.  Therefore, the use of a one (1) year average for onsite data could presumably be utilized as outlined in Appendix W of 40 CFR Part 51.  The NO2 modeling guidance document can be found here.

U.S. EPA Promulgates Final Air Toxics Standards for Compression Ignition RICE

On March 3, 2010, U.S. EPA promulgated final National Emissions Standards for Hazardous Air Pollutants (NESHAP) for existing compression ignition (CI) stationary Reciprocating Internal Combustion Engines (RICE) that were not previously regulated by the existing, so called, RICE MACT (i.e., 40 CFR Part 63, Subpart ZZZZ).  The RICE MACT rule was originally promulgated in 2004.  The March 3, 2010 final rule sets limits on emissions of carbon monoxide (CO) and formaldehyde (CH2O) for the following units: 

1. CI RICE located at area sources of air toxics emissions,
2. CI RICE with site ratings of less than or equal to 500 brake horsepower (bhp) located at major sources of air toxics emissions that were constructed or reconstructed before June 12, 2006, and
3. CI RICE with site ratings of greater than 500 bhp located at major sources of air toxics emissions that were constructed or reconstructed before December 19, 2002. 

RICE affected by the March 3, 2010 final rule are typically located at power plants and chemical and manufacturing facilities, and are used to generate electricity in periods of utility power outages or to power pumps and/or compressors.  However, many other types of facilities use emergency generators that will now be covered by the rule.  For example, information technology (IT) and/or business sector companies utilizing emergency generators to power servers in times of utility power outages will also be affected as well as hospitals, municipalities (e.g., sanitary pumping stations, wastewater treatment plants), detention centers,  and other operations that rely on back-up power generation.

The March 3, 2010 final rule is the result of revisions to the rule originally proposed on February 25, 2009.  The February 25, 2009 proposed revisions originally included requirements and emission standards affecting both CI RICE and spark ignition (SI) RICE.  However, U.S. EPA has only promulgated those portions of the proposed revisions that affect CI RICE.  U.S. EPA projects that final emission standards for existing SI RICE that burn gasoline, natural gas, and landfill gas will be promulgated by August 10, 2010.

The Usual Suspects – U.S. EPA 2011 – 2013 Enforcement Initiatives

The U.S. Environmental Protection Agency (U.S. EPA) has announced its 2011 through 2013 National Enforcement Initiatives to handle national environmental and public health problems. For air pollution, the initiatives include addressing air pollution from the usual suspects: the largest sources of particulate matter, nitrogen oxides, and sulfur dioxide.  This includes continued recent enforcement actions on coal-fired utilities and cement, glass, and acid production facilities.  U.S. EPA will also be targeting to protect the health of communities from toxic air pollution resulting from excess emissions through enforcement of existing MACT rules and with a new enforcement initiative for excess emissions from startup, shutdown, and malfunction events.  U.S. EPA has recently announced a number of enforcement settlements that are directly in line with these announced priorities.  ALL4 expects increased enforcement actions by U.S. EPA to target many previously identified New Source Review (NSR) permitting violations and events where it determines that excess toxic emissions resulted from non-routine operations.  In addition to the air pollution initiatives directed towards large sources and excess emissions of hazardous air pollutants, U.S. EPA also announced enforcement initiatives that target stormwater and raw sewage discharges, groundwater contamination by confined animal feeding operations (CAFOs), multi-media discharges from mineral processing operations, and multi-media impacts associated with resource extraction operations.  A summary of U.S. EPA’s enforcement goals can be viewed here.