EPA Moves to Designate Denver Region Nonattainment Area as ‘Serious’

On Thursday, August 8, 2019, the Environmental Protection Agency (EPA) proposed the Denver metro area failed to meet federal air quality standards by the provided deadline and is initiating action that will lead to more stringent regulatory requirements. The proposed rulemaking was published to the Federal Register on August 15th, opening up the 30-day public commenting period.

Some Background
EPA specifies a maximum allowable air concentration for ozone in outdoor air, referred to as a National Ambient Air Quality Standards (NAAQS).  Although the formula to determine whether a region exceeds the NAAQS standards is complex, the impact of violating this standard is significant.  Areas where air quality does not meet specified standards become nonattainment areas.  Nonattainment areas can be designated as marginal, moderate, serious, severe, or extreme.  Under the 2008 NAAQS, areas had to improve air quality to 75 parts per billion (ppb) by 2018.  With portions of Colorado averaging 79 ppb between 2015-2017, the EPA proposed reclassifying the Denver-North Front Range Nonattainment Area from moderate to serious.

How Serious is Serious?
When the EPA finalizes this change to the Denver-North Front Range, the Colorado Department of Public Health & Environment (CDPHE) will be required to apply a higher degree of scrutiny to emissions sources. Once an area becomes "serious," the state must revise its State Implementation Plan (SIP) to comply with more stringent regulatory requirements. Revisions include establishing new reasonably available control technology (RACT) requirements, and for many sources, would require installation of new volatile organic compounds (VOC) and NOx controls.

There's More
The move to a serious classification will also lead to more complex permitting requirements.  Under the current "moderate" nonattainment area classification, about 200 sources have potential VOC or NOx emissions greater than 100 tons per year, and as such, must have a Title V permit.  Under a "serious" classification, the standard moves to 50 tons per year, and the CDPHE estimates an additional 600 sources would be required to apply for Title V permits. Additionally, current permits would have to be modified to reflect the new standards, and new construction projects will be required to obtain emission offsets to ensure overall VOC and NOx emissions are reduced.

Location, Location, Location
A notable complication for Colorado is that standards are applied in a one-size-fits-all approach.  Denver's mountainous topography combined with its geographic weather systems can act as a net, capturing global pollutants and holding them in the area.  This – combined with the fact that standards only become tougher under a serious classification – complicates the Denver-North Front Range region's ability to meet requirements.

Can I Provide Feedback?
You can.  EPA will hold a public hearing September 6, 2019 at 9:00am at the Agency’s Region 8 office (1595 Wynkoop St., Denver, CO 80202) and written comments can be made through September 16, 2019.

What to Learn More?
Contact a Trihydro team member today:

John Pfeffer, Senior Air Professional

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