Memorandum to Docket EPA-HQ-RCRA-2010-0695

Subject: Personal Communication with Vince Holohan, PHMSA, U.S. DOT 

From: Ross Elliott, U.S. EPA, Mark Baldwin, U.S. EPA. 

Date: 03/09/2011

Summary

On 3/9/2011, in response to an inquiry from Ross Elliott of U.S. EPA regarding the regulatory

status and definition of supercritical CO2 under 49 CFR Part 195, U.S. Department of 

Transportation’s (U.S. DOT) Pipeline and Hazardous Materials Safety Administration (PHMSA) 

engineer Vincent Holohan provided clarity on how PHMSA regulates the transportation of CO2

via pipeline. Of particular interest to U.S. EPA was determining if federal regulations governing 

the transportation of supercritical CO2 via pipeline would be affected by a potential RCRA 

hazardous waste classification.

Mr Holohan stated, “Accordingly, if EPA classifies CO2 as a hazardous waste for purposes of the 

environmental laws it enforces, that would not diminish or otherwise affect the authority of 

PHMSA's Office of Pipeline Safety to regulate the safe transportation of CO2 as a liquid.” 

Furthermore, because PHMSA’s pipeline regulations do not differentiate between a commodity

supercritical CO2 stream and a waste supercritical CO2 stream, all CO2 pipelines would need to 

comply with safety requirements found in 49 CFR 195. For additional information regarding the 

correspondence please see the attached email.
Elliott,

Sorry for the delayed response as I was checking with other parts of PHMSA. 

First, to the extent your question involves hazmat (HM) authority in Chapter 

51 of Title 49, U.S. Code and CFR Parts 172 and 173, be advised that pipeline 

safety authority comes from an entirely different organic act and is found in 

Chapter 601 of Title 49, U.S. Code. Even if a (non-petroleum) substance is 

regulated for HM purposes under Chapter 51 and is in the HM table in Part 

172, that does not mean it is automatically regulated for pipeline safety 

purposes under Chapter 601.

Second, with respect to the safe transportation of CO2 by pipeline, there is 

a specific controlling statute: 49 USC 60102(i). It clearly gives PHMSA 

authority to regulate the transportation of CO2 by pipeline as a liquid 

(i.e., in a supercritical fluid phase), but expressly excludes the 

transportation of CO2 as a gas.

Third, note that PHMSA does not need to classify a substance as "waste" to 

regulate its safe transportation by pipeline. If a substance is flammable, 

toxic, or corrosive it would likely be regulated for purposes of pipeline 

safety regardless of whether it was in pure "virgin" form or was mixed with 

other substances/contaminates as a result of being produced from some 

industrial process. In other words, if it is flammable, toxic or corrosive, 

its origin does not matter for purposes of PHMSA's pipeline safety authority 

and there is no need for PHMSA to designate it as "waste."

Accordingly, if EPA classifies CO2 as a hazardous waste for purposes of the 

environmental laws it enforces, that would not diminish or otherwise affect 

the authority of PHMSA's Office of Pipeline Safety to regulate the safe 

transportation of CO2 as a liquid.

To the extent you have questions about the hazmat table in Part 172 or the 

transportation of CO2 by means other than pipeline (such as in tanks, 

containers, and vessels), please contact Joe Solomey, Asst. Chief Counsel for 

HAZMAT, at 202-366-0977. Let me know if you have further questions regarding 

pipelines. I hope that this helps. Thanks.

Vinnie

Vincent D. Holohan

Engineer

US Department of Transportation

Pipeline and Hazardous 

Materials Safety Administration

1200 New Jersey Ave, SE

E22-203

Washington, DC 20590

202-366-1933 (o)

202-493-2311 (f)

vincent.holohan@dot.gov