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

Excess Emission CEMS vs Compliance CEMS in Subpart Db

Nov 7, 2018
Nov 7, 2018

For some reason, NOx CEMS in Subpart Db seems to be coming up a lot lately in my work. I have recently had several conversations with clients and regulatory agencies regarding how NOx CEMS are treated in Subpart Db. And there seems to be some[…]

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Btu per SQUARE FOOT? What the heck is EPA’s Flare Dilution Factor?

Oct 12, 2018
Oct 12, 2018

OK… This is a long one.

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Danny Landry: Drones for Inspection and Air Quality Monitoring

Sep 27, 2018
Sep 27, 2018

Danny Landry is a pioneering entrepreneur in the field of drone (or UAV) use for industrial inspection and air quality monitoring. In this episode of Hot Air, I talk with Danny about various UAV applications in air quality monitoring, optical gas[…]

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Jim Guenthoer: The Successful Stack Test

Sep 27, 2018
Sep 27, 2018

In these inaugural episodes of CleanAir's podcast series Hot Air, I sit down with Jim Guenthoer to talk about the elements necessary for a successful stack test. Jim brings his 40+ years of stack testing experience to the table and provides lots[…]

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It’s Time to Rethink Flare Velocity Limits

Sep 26, 2018
Sep 26, 2018

US EPA’s flare velocity limits were originally issued in 1986. Since then, they have found their way into flare regulations around the world. They were developed following a series of EPA sponsored tests conducted in the 1980’s that examined how[…]

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The ACE Rule: When is an Emission Increase an Emission Increase?

Aug 21, 2018
Aug 21, 2018

The Trump EPA's new Affordable Clean Energy (ACE) rule proposal announced today aims to replace the Obama EPA's Clean Power Plan (CPP) for limiting CO2 emissions from coal-fired power plants. The new proposal finds that the Best System of[…]

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New Flare Consent Decree: WRB Refining/Phillips 66

Aug 20, 2018
Aug 20, 2018

On August 10, 2018, the US Department of Justice lodged a proposed consent decree with the United States District Court for the Southern District of Illinois in the lawsuit entitled United States and Illinois v. WRB Refining LP, et al., Civil[…]

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What's Up with MATS? The Rule 28 Years in the Making and Still Cookin'

Jul 17, 2018
Jul 17, 2018

EPA’s long-suffering Mercury and Air Toxics Standards (MATS) rule regulates emissions of mercury and other air toxics from coal-fired power plants. The rule has its origins 28 years ago with the passage of the Clean Air Act of 1990. The Act[…]

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infoBits: Condensable Particulate Sampling Bias

May 4, 2018
May 4, 2018
  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[…]

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EPA Responses to Refinery Flare AMELs Hit Federal Register

Apr 25, 2018
Apr 25, 2018

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[…]

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EPA Proposes Refinery Sector Rule Amendments - Part 2

Mar 21, 2018
Mar 21, 2018

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.

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EPA Proposes Refinery Sector Rule Amendments - Part 1

Mar 20, 2018
Mar 20, 2018

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[…]

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EPA Finalizes New Enclosed Flare AP-42 Emission Factors

Mar 20, 2018
Mar 20, 2018

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[…]

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Shell Flare Consent Decree Lodged

Feb 16, 2018
Feb 16, 2018

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[…]

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infoBits: Smoking Flares

Feb 6, 2018
Feb 6, 2018
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[…]
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