PHMSA Offers HCA Guidance to Owners and Operators of Gas Pipelines

PHMSA Issues Guidance on Best Practices for Identifying and Verifying High Consequence Pipeline Areas

On December 12, 2016, PHMSA issued an Advisory Bulletin to owners and operators of gas pipelines to provide guidance on how to identify and periodically confirm High Consequence Pipeline areas. The advisory also recommends operators add a buffer zone to an area of potential impact to help ensure proper high consequence area identification. Read more about PHMSA’s update here.

The advisory bulletin in the Federal Register provides suggestions for accurately mapping and integrating High Consequence Areas (HCAs) data, documenting how mapping systems are used, periodically verifying and updating their mapping systems, utilizing buffer zones (tolerances) to provide additional protection around the calculated potential impact radius (PIR) along their pipelines, and ensuring the accuracy of class locations. The bulletin emphasizes that HCA identification relies on pipeline-specific information regarding the location, size, and operating characteristics of the line, as well as the identification of structures, specified sites, and their intended usage along the pipeline right-of-way.

PHMSA provided the basis for defining HCAs- Get the details here.

  1. A facility housing person of limited mobility, or
  2. An outdoor area where people congregate and which is occupied by 20 or more people on at least 50 days per year, or
  3. A building occupied by 20 or more people 5 days per week, 10 weeks in any 12-month period

Following the publication of the regulations and advisory bulletin, PHMSA inspections have revealed that operators may need further guidance regarding the identification of HCAs, as operators have been inconsistent in determining HCAs using “identified sites.”

A list of PHMSA-provide frequently asked questions on this subject can be found on the gas IM site at

PHMSA recommends operators frequently and consistently review their data- including class location data- for potential inaccuracies or limitations, and add a buffer zone to the calculated PIR to help ensure proper HCA identification. The purpose and usage of buildings, open structures, and outside areas can shift over time, changing the number of “identified sites” in a PIR, and therefore, whether an area is an HCA. PHMSA believes that if operators review class location and PIR data on an annual basis as a part of the Integrity Management (IM) programs, the accuracy of HCA determinations will be greatly improved.