Browsing the ADI Updates

From time-to-time, U.S. EPA will publish a Federal Register notice announcing updates to the Applicability Determination Index (ADI).  The ADI is a searchable database that contains memoranda issued by U.S. EPA on applicability and compliance issues associated with regulations such as Standards of Performance for New Stationary Sources (NSPS), National Emissions Standards for Hazardous Air Pollutants (NESHAP), chlorofluorocarbons (CFC), etc.  On May 22, 2012, U.S. EPA announced forty-four new postings to the ADI.  It is always prudent to browse the updates to take a quick look to see what the regulated community is “petitioning for” or “seeking clarification of” from U.S. EPA.  The ADI update that caught my eye this time was not a recent development, but something to add to my own regulatory library.  U.S. EPA is denying alternative monitoring petitions (AMP) for sources with wet scrubbers that propose parametric monitoring in lieu of continuous opacity monitoring systems (COMS) for sources subject 40 CFR 60 Subpart Db.  COMS are not effective in moisture saturated exhaust stacks due to the interference of the water droplets with the opacity monitor.  For regulations that have a particulate matter (PM) continuous emission monitoring system (CEMS) as an alternative compliance option, such as 40 CFR 60 Subpart Db, it looks like U.S. EPA may require a PM CEMS (which can be installed on “wet stacks”) in lieu of a COMS.  Petitions that are submitted to the ADI are handled on a case-by-case basis by U.S. EPA, and you can make your case for a parametric monitoring system.  However, it looks like these types of requests may not be approved thereby requiring the installation and certification of costly PM CEMS.  The ADI is full of these glimpses of U.S. EPA thoughts that can influence the direction of a project.  It is one my first stops when planning a project.  The ADI is found at www.epa.gov/compliance/monitoring/programs/caa/adi.html.