What's About to Happen?
Ten counties, including a large portion of Weld County, are part of the Denver Metro North Front Range (DMNFR) ozone non-attainment area. The area is currently classified as "Moderate" for the 2008 standard and "Marginal" for the more stringent 2015 ozone standard. Though ozone concentrations as measured by various monitoring stations are decreasing, the trend is slow and there are still enough exceedances that the area is expected to be re-classified as "Serious" for the 2008 standard in the next few months.
Among the various impacts from the new classification are lower emission thresholds for permitting requirements for new or modified sources, and more stringent controls for some existing sources. The latter is known as Reasonable Available Control Technology or RACT.
When the "Serious" classification is finalized, more existing sources such as backup generator engines, medium sized boilers, tank batteries, and many other sources of nitrogen oxides and/or volatile organic compounds may be required to retroactively consider adding new or additional emission controls. Alternately, a source might avoid the expense of implementing RACT by voluntarily reducing emissions by taking limits on processing or operation time. There are other options as well, but the bottom line is permitting and operating many common emission sources will become more complicated and expensive.
What is RACT?
Section 182(b)(2) of the federal Clean Air Act requires State Implementation Plans (SIP) for ozone nonattainment areas classified as "Moderate" and worse to include requirements for existing major sources of ozone precursor pollutants (VOC and NOx) to apply RACT. Per 44 FR 53762, RACT is defined as "the lowest emission limitation that a particular source is capable of meeting by the application of control technology that is reasonably available considering technological and economic feasibility". The Colorado Air Quality Control Commission Common Provisions Regulation Section I.G further states that "[RACT] may require technology that has been applied to similar, but not necessarily identical, source categories. It is not intended that extensive research and development be conducted before a given control technology can be applied to the source. This does not preclude requiring a short-term evaluation program to permit the application of a given technology to a particular type of source."
In plain language, if some facility, anywhere in the US, has successfully implemented a control method or technique to reduce emissions on a broad source category (e.g. engines of certain size and/or fuel use), that control method or technique could be required on your source.
It's a bit more complicated than the plain language version, of course, but when the CDPHE makes RACT "easy" it's by specifically defining RACT for a broad category of sources. For example, an older engine may become subject to modern performance standards. You might say, it's not economically feasible to make my old engine comply with the current standard, but then you have to formally prove that with a defendable "RACT analysis".
What Can Facilities Do Now?
The last round of RACT implementation occurred in 2017 when the non-attainment area was bumped up to "Moderate". In that round, approximately 50 facilities were impacted. The state is currently evaluating which sources and facilities will be pulled into RACT when the area is re-classified again to "Serious", but with the lower emission thresholds, that number could be in the hundreds.
Some facilities have already received notice that new RACT analyses will likely be required. While RACT may be a complicated process, there's enough history here in Colorado and around the nation that a simple analysis of your facility's emission sources and emissions can provide a measure of risk.