EPA’s Newest SO2 Requirements and

What You Need To Know

October 8, 2015

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On August 10, 2015, the U.S. Environmental Protection Agency (EPA) finalized requirements for air agencies to monitor or model ambient sulfur dioxide (SO2) levels in areas with large sources of SO2 emissions. This comes as a result of EPA’s 2010 ruling on the 1-hour SO2 National Air Ambient Quality Standard (NAAQS).

 

Here is what you need to know:

 

• At a minimum, air agencies must characterize air quality around sources that emit 2,000 tons per year (tpy) or more of SO2.

 

For these sources, state agencies would opt either to locate ambient SO2 monitors nearby; or to have either the facility emitting the source conduct the modeling analysis, or the agency themselves conduct the modeling analysis. EPA is recommending that state agencies work with these sources to determine and implement, if needed, any federally enforceable emission limits. This would allow the states to avoid nonattainment designations and the requirements placed both on the states and on future development that such a designation brings.

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• There are benefits for a facility to conducts its own air modeling.

 

Given the certainty of the new rule, we expect that the majority of these facilities would opt to conduct an air dispersion modeling analysis of their facility themselves, rather than let the state agencies conduct it for them. Benefits include:

 

• Ambient monitoring tends to be more costly and time consuming. By self-evaluating through modeling, facilities can decide immediately what their options might be. The options would likely include changes to emission limits, fuel changes, physical changes (stacks, air pollution control equipment, etc.), or actual operational restrictions.

 

• Modeling can evaluate effects the changes would have to the predicted concentrations. Initial results are obtained within weeks and decisions can be determined on alternative options quickly. It should be noted that any modifications to the facility (physically or operationally) to comply with the 1-hour SO2 NAAQS would be made to the current permits as a federally enforceable permit condition. 

 

• Minimize outside involvement. Environmental groups have been known to acquire source data from existing permits (freely available through the Freedom of Information Act). Groups may choose to conduct modeling with their own specialists and submit their findings (good or bad) to local agencies.

 

For a more information on EPA’s Programs and Requirements for Reducing Sulfur Dioxide, click here.

 

If your facility would like support in modeling to determine if your facility meets this updated requirement, contact us.

 

Epsilon’s talented team of Certified Consulting Meteorologists (CCMs) and air quality engineers provide dispersion modeling and engineering services. In the event of modeled SO2 levels above the standard, Epsilon’s air quality will provide facilities with advice on operational changes, which, if possible, would be more amenable than physical air pollution controls or process modifications.