With spring season well underway, gas pipeline operators have been gathering and compiling annual report data related to Pipeline and Hazardous Materials Safety Administration (PHMSA) requirements. This year, 2022, is a bit different than previous years as new criteria are required in the newly updated form. A new term, moderate consequence areas (MCAs), has emerged since the PHMSA Mega Rule was in development and MCAs are now required to be reported annually to the PHMSA.

The Mega Rule — which focuses on safety standards and procedures for pipeline owners and operators — is well into its second year of publication. As a result, many operators have already changed the way they are documenting and handling records and information for pipeline safety, including MCA reporting. MCAs are defined under PHMSA’s 49 CFR Part 192.3 as:

An onshore area that is within a potential impact circle, as defined in Part 192.903, containing either:

(i) Five or more buildings intended for human occupancy; or

(ii) Any portion of the paved surface, including shoulders, of a designated interstate, other freeway, or expressway, as well as any other principal arterial roadway with 4 or more lanes, as defined in the Federal Highway Administration's Highway Functional Classification Concepts, Criteria and Procedures, Section 3.1, and that does not meet the definition of high consequence area, as defined in Part 192.903.

When identifying high consequence areas (HCAs), consideration similarly includes buildings intended for human occupancy. The big differences, however, are in the number of buildings intended for human occupancy within a potential impact circle and a new consideration for principal arterial roadways.

The new definition focuses on human safety, as well as the risk of damage to critical infrastructure, when a pipeline incident occurs. Now that operators must report mileage of paved surfaces and accompanying assessments and repairs, they have a better understanding of the areas outside of their HCAs and can mitigate potential risks to their pipeline systems and surrounding areas that may not have been previously considered.

The first stage in identifying MCAs is reviewing their pipeline system in a spatial format, ideally with a geographic information system. Much like for HCAs, a potential impact radius will need to be calculated (per Part 192.903) and the resulting potential impact circle is then utilized to determine the MCA segments along the pipeline(s). Criteria are provided under 49 CFR Part 192.3 for determining the MCAs and associated axial length along the pipeline. Structure data from current HCA studies may be utilized for the MCA determination, but roadway data will likely need to be procured, which can be obtained from the Federal Highway Administration. One thing to remember is that if it is an HCA, it can’t also be an MCA.

The second stage includes initial or baseline assessment of the MCAs. If the pipeline segments identify as an MCA, operate at or above 30% specified minimum yield strength, and can accommodate inline inspection (ILI) tools, they must have initial assessments complete by July 3, 2034 (or as soon as practicable but not to exceed 10 years after the pipeline segments meet the conditions of Part 192.710(a)). ILIs are performed using tools commonly called “smart pigs,” which have on-board electronic sensors and computer processors that travel through a pipeline to record information about the internal and external conditions of the pipeline. The requirement for the MCA to be piggable does not require that an ILI tool be used as the assessment method, as operators are able to choose any method that is similarly used for assessments of HCAs. The inclusion of piggable MCAs is intended to limit the immediate burden that these additional inspections may create. Potential requirement updates to convert existing non-piggable MCA segments to piggable do not seem likely as of now based on cost-benefit analysis, but operators are required under Part 192.150 to design and construct any new transmission line or replacement to accommodate the passage of internal inspection devices.

The last stage is the continual or periodic reassessments of the MCAs, which shall be performed at least once every 10 years, but not to exceed 126 months, as required by Part 192.710. Depending on the number of MCAs that will require assessments, it may be necessary for operators to develop a staggered assessment strategy, as to not overload themselves to meet the deadlines for completion. Good record keeping is also a critical factor; this will be vital for tracking assessments, repairs and the data necessary for reporting.

Maintaining pipeline operations that are safe for people, the environment and other nearby infrastructure is the goal; identifying MCAs is one big step in achieving that.


The PHMSA Mega Rule creates both challenges and opportunities for utility operators.

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Faye Cradit, senior pipeline integrity engineer at Burns & McDonnell, has more than 18 years of industry experience. In her role, she has developed a passion for working with and helping clients operate and maintain their assets with safety and compliance in mind.