CleanAir Blog

Scott Evans

Mr. Evans has over 30 years experience in the air pollution field. Currently, Mr. Evans directs Clean Air’s Consulting Group and is involved with a variety of research projects, white papers, and industry presentations. As Technical Leader of the Consulting Group, his responsibilities include tracking United States and international legislation and regulations affecting Clean Air clients and advising clients on the impact of new and existing regulations. He prepares regulatory briefs for Clean Air personnel and clients on issues such as test method applicability and development, data quality issues, and permitting. Mr. Evans lectures extensively on these and a variety of other air quality issues. Much of Mr. Evans recent work involves assisting refiners and petrochemical plants with issues involving industrial flares as well as implementation of EPA regulations such as NSPS Subpart Ja, MACT Subpart CC, and others. In this regard, Mr. Evans has provided technical support and consulting to several refineries and petrochemical producers involved in consent decree negotiations with US EPA regarding flare performance and efficiency and has participated at the table in these negotiations on behalf of industry. He has been directly involved with the planning and execution of most of the flare test projects that have occurred since 2009. He has provided litigation support services on flare related issues on such topics as: evaluation of true combustion/destruction efficiency, proper assist ratios for assisted flares, debunking flare analyses based on FLIR infrared and visual observation/photographs, viability of flare gas recovery, general flare performance issues, strategies for reduction of supplemental gas, and other related topics.

Posts by Scott Evans

infoBits: Condensable Particulate Sampling Bias

  1. Particulate is defined by the method used to measure it. Unlike chemically distinct emissions like carbon monoxide or nitrogen oxide, “particulate” can be composed of many different distinct compounds. Some of these compounds may be volatile[…]


EPA Responses to Refinery Flare AMELs Hit Federal Register

EPA today published their response to Alternative Means of Emission Limitation (AMEL) requests from four refineries and a chemical plant. These are: ExxonMobil (Baytown), Marathon (GBR and Garyville), Chalmette (Chalmette), and the chemical plant[…]


EPA Proposes Refinery Sector Rule Amendments - Part 2

This is Part 2 of my blog post on EPA's proposed amendments to the Refinery Sector Rule (RSR). Part 1 covered changes to Subpart CC (MACT 1). Part 2 covers changes to Subpart UUU (MACT 2) and Subpart Ja.


EPA Proposes Refinery Sector Rule Amendments - Part 1

On Monday, March 19, 2018, US EPA issued proposed amendments to the Refinery Sector Rule (RSR). These amendments are based on three petitions of reconsideration filed with the agency -- two of these were joint submissions by the American[…]


EPA Finalizes New Enclosed Flare AP-42 Emission Factors

On February 5, 2018, the EPA finalized its review of the existing VOC emissions factor for flares at natural gas production sites.

EPA evaluated test data available for flares at natural gas production sites, data from testing conducted by[…]


Shell Flare Consent Decree Lodged

On February 12, 2018, the Department of Justice lodged a proposed consent decree with the United States District Court for the Eastern District of Louisiana. The alleged violations involve flares used at a chemical plant owned and operated by Shell[…]


infoBits: Smoking Flares

1) Flares tend to smoke (produce soot) in fuel-rich areas of the combustion zone when there is insufficient oxygen/temperature to complete the combustion process. In high efficiency flames, visible soot is produced within the combustion zone and[…]

Lima Refining Company Flare Consent Decree

The Department of Justice recently entered a Consent Decree with the United States District Court for the Northern District of Ohio in the lawsuit entitled United States v. Lima Refining Company, Civil Action No. 3:17-cv-01320-JZ.Among other issues[…]

Proposed Exxon Mobil flare consent decree

On October 31, 2017, the Department of Justice lodged a proposed consent decree with the United States District Court for the Southern District of Texas in the lawsuit entitled United States and the Louisiana Department of Environmental Quality[…]


New Flare Consent Decree Lodged

A new flare consent decree has been released by the Department of Justice. Excerpt from the June 6, 2017 Federal Register...

On May 30, 2017, the Department of Justice lodged a proposed Consent Decree with the United States District Court for the[…]


Flare Nerdvana: Flare Velocity Limits - Part 1

I know, I know.... You are asking yourself "Where has this video on flare velocity limits been all my life?" Well, the wait is over. In this first (of potentially several) videos on miscellaneous flare topics, I discuss those pesky flare velocity[…]


Using Drones to Measure Stack Emissions

On a recent project, CleanAir used an open-path Active FTIR (AFTIR) system coupled with a drone (or unmanned aerial vehicle, UAV) to analyze pollutants in on a high, inaccessible stack. This is not the Passive FTIR system employed in many of the[…]