U.S. EPA’s Recent Round of ADI Updates and Key Takeaways

This article is available as a podcast episode on ALL4’s Air Quality Insider

The United States Environmental Protection Agency (U.S. EPA) intermittently publishes Federal Register notices announcing updates made to the Applicability Determination Index (ADI).  The ADI is a database containing notices that determine applicability and compliance with the New Source Performance Standards (NSPS), National Emissions Standards for Hazardous Air Pollutants (NESHAP), and chlorofluorocarbons (CFC).  We discussed ADI’s last year in our 4 The Record Article: “U.S. EPA’s Recent Interpretations on Refinery Rule Alternative Monitoring Plans: Helping Pave a Path to Facilitate Your Facility’s Compliance“.  The most recent summary from U.S. EPA contained 54 new determinations and was released on May 16, 2018.  While a large variety of topics are covered in the ADI, it is often wise to do a quick scan of the determinations to gather an idea of what types of requests are being made and where U.S. EPA’s decisions fall on these matters.  I noticed many of the submissions regarded the approval of alternative monitoring petitions (AMP), often centered on the feasibility of continuous monitoring systems (CMS), replacing calibration gasses, and wet versus dry basis concentration monitoring.

Alternate Monitoring Petitions for Atypical Operation Periods

Keeping with a theme seen in the 2017 ADI update, several of the ADI Determinations were requests for U.S. EPA approval of an AMP for monitoring airborne chemical concentrations during infrequent and short-term operations.  Examples of these would be degassing, cleaning, and maintenance activities.

• Numerous refiners¹ subject to Subpart 40 CFR Part 60, Subpart J (Standards of Performance for Petroleum Refineries) and 40 CFR Part 60, Subpart Ja (Standards of Performance for Petroleum Refineries for Which Construction, Reconstruction, or Modification Commenced After October 14, 2011) were successful in receiving AMP approval to not install the hydrogen sulfide (H₂S) and sulfur dioxide (SO₂) continuous emissions monitoring system (CEMS) for fuel gas combustion devices for temporary and portable thermal oxidizer(s) or flare(s).  U.S. EPA recognized the impractical nature of installing CEMS on thermal oxidizers used for intermittent operations such as tank degassing and other operations that use a temporary and portable thermal oxidizer for the purposes of volatile organic compound (VOC) destruction.  U.S. EPA denoted that because the thermal oxidizers are temporary and portable it was economically infeasible and technically impractical to install CEMS for H₂S or SO₂ monitoring.

In each instance, U.S. EPA approved substituted monitoring measures (e.g., colorimetric stain tubes for determination #1700023) that can be completed before or during the operation of the short-term equipment.  One important thing to note is that the approved AMP expires on the effective date of any changes U.S. EPA makes to the pertinent Federal code.

Calibration Gas Safety

U.S. EPA fielded several requests for the replacement of calibration gasses with those of lower concentrations.  Multiple refiners² subject to Subpart Ja and 40 CFR Part 60, Subpart A (General Provisions), received approval for alternative Quality Assurance/ Quality Control (QA/QC) requirements to eliminate the daily use of potentially dangerous high concentration calibration gases on a routine basis because of safety concerns.  These requests were in regard to daily calibration checks and cylinder gas audits (CGAs), and the U.S. EPA approved AMPs with modified high-level concentrations for those two tests.  As was the case in 2017, most of the AMPs were conditionally approved with occasional testing of high concentration calibration gas being required, often on a three-year basis.  Most of our avid readers will recognize this is yet another continued trend in U.S. EPA determinations from previous summaries.

Wet basis vs. Dry basis Continuous Monitoring

The final theme I noticed was the inclusion of determination submissions surrounding the substitution of wet basis continuous emission monitoring system (CEMS) data for dry basis values required by Federal codes.  In several instances, this methodology was approved. Requests to monitor minimum percent oxygen gas (% O₂) limits using wet basis CEMS during startup and shutdown were unconditionally approved³.  The reason for these AMPs was the potential disruption of analyzer that dry basis measurement presents.  Both requests were justified by expressing concerns with catalyst fines plugging the analyzer, resulting in greater downtime.  U.S. EPA allowed wet basis concentration to be substituted when minimum % O₂ was in question, as wet basis oxygen concentration will always be lower.  As such, if wet basis % O₂ passes, dry basis would pass.

In more complex situations, it was requested that wet basis measurements of gas concentrations be submitted for dry basis, using moisture factors and U.S. EPA approved equation.  An interesting case study of this can be seen comparing ADI #’s 1700019 and 1700034.  In both circumstances, the applicant was requesting an alternative wet basis monitoring method.  Both applicants requested the ability to make the conversion from wet to dry-basis using a static moisture factor.  U.S. EPA noted that Performance Specification 2 of Appendix B to Part 60 allows data to be monitored on a dry basis or be corrected to a dry basis using continuously monitored moisture data.  For this reason, ADI #1700019 was denied.  However, ADI #1700034 was approved under very specific conditions laid out by U.S. EPA.  The facility was given roughly half of a year to use the requested approach while a dry-basis CEMS was being installed to monitor O₂ and SO₂ concentrations.  This is important to know for any clients looking to use an alternative monitoring method on a temporary basis until the proper systems can be installed.

A review of U.S. EPA’s yearly ADI update is an effective method for staying informed of recent regulatory determinations that affect your industry.  This review of the determinations can provide information to use when requesting an applicability determination from U.S. EPA, providing insights that may lead to a higher likelihood of success.  The requested approvals may also provide potential solutions that your facility hasn’t considered for demonstrating compliance.  You can always reach out to ALL4 to discuss recent determinations and interpretations.  ALL4 regularly assists clients in tracking regulatory changes including U.S. EPA determinations and interpretations. Our goal is to keep the regulated community informed and to maintain our own knowledge base so that we can assist our clients with optimum compliance strategies.  If you have any questions, feel free to reach out to me at 610.933.5246 x172 or email at mgray@all4inc.com.