In the aftermath of a natural gas pipeline explosion on September 9, 2010 in San Bruno, California, the National Transportation Safety Board (NTSB) identified several concerns with the Pipeline and Hazardous Materials Safety Administration’s (PHMSA’s) oversight of performance-based safety programs, and recommended that the Secretary of Transportation conduct an audit to address these concerns.

Pipeline safety in the U.S. and many other parts of the world relies on the regulatory concept of Integrity Management. Integrity Management programs – required by the federal Pipeline and Hazardous Materials Safety Administration (PHMSA)– stipulate how and where pipeline operators must identify, prioritize, assess, evaluate, repair, and validate the integrity of their pipelines that could, in the event of a leak or failure, endanger human health.

san bruno explosion

The San Bruno pipeline explosion killed eight people at 6:11 pm PDT on September 9, 2010.

Until recently, Integrity Management programs primarily focused on managing risks to human health in High Consequence Areas (HCAs), generally defined as areas along a pipeline in which 20 or more buildings intended for human occupancy could be significantly impacted in the occurrence of a pipeline failure. In other words, the buildings fall within the pipeline’s potential impact radius (see Figure 1). While the potential consequences of a pipeline accident are deemed higher within HCAs, nearly half of all pipeline accident-induced injuries, property damages, and fatalities have occurred outside of HCAs since the promulgation of Integrity Management rules.

Signaling an industry-wide move toward more comprehensive risk management, PHMSA released new rules on October 1, 2019 that expand Integrity Management programs for gas transmission pipelines beyond HCAs to include Moderate Consequence Areas (MCAs). MCAs are defined as areas along a pipeline in which 5 or more buildings intended for human occupancy are located within the pipeline’s potential impact radius in the event of a failure (down from HCAs’ 20-building threshold) (§ 192.3). Additionally, MCAs include sites where 4-or-more-lane arterial roadways are located within a pipeline’s potential impact radius.

medium consequence areas as defined by new PHMSA regulation

Figure 1. Example of how a pipeline’s potential impact radius and nearby structures interact to determine High Consequence Areas and Medium Consequence Areas where operators must implement Integrity Management programs. Wherever an MCA is identified, operators must conduct integrity assessments (§ 192.710) and reconfirm the pipeline segments’ Maximum Allowable Operating Pressure (MAOP) (§ 192.624).


According to the new rules, MAOP reconfirmations are required for all HCA and MCA pipelines segments that can accommodate inline inspection instruments and whose MAOP is equal to or greater than 30% of the pipeline’s specified minimum yield strength(§ 192.624).Operators must develop procedures for MAOP reconfirmation of qualifying MCAs by July 1, 2021.

The new rules present a tight timeline for compliance. If operators are to meet the deadline of producing MAOP reconfirmation procedures by mid-2021, they must immediately begin to identify the newly required MCAs – zones that operators have never needed to consider until now.The arc of policy is pushing the pipeline industry evermore toward risk abatement and stewardship of human health. SolSpec’s mission is to help industry efficiently align with and lead the trajectory toward safety and sustainability. SolSpec uses high-performance computing and artificial intelligence to empower operators with fast, meaningful data and analytics that set the bar for hazard identification and prediction, resource allocation, and risk management.

Traditional integrity management programs focus on the integrity of the pipeline; yet, a pipeline’s safety also depends on the stability of its surrounding environment. The Right-of-Way Integrity Management solution addresses external threats to pipelines for a more complete integrity program. The RIMSpec’s annual subscription includes access to high-fidelity terrain and orthomosaic libraries through SolSTAC, access to the SolSpec viewer and deliverables in the form of risk prioritization, monitoring plans, emergency response plans, and analytic layers.

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