NTSB Safety Recommendation P-15-012

NTSB safety recommendation P-15-012.

TO THE PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION: Evaluate the safety benefits of the four risk assessment approaches currently allowed by the gas integrity management regulations; determine whether they produce a comparable safety benefit; and disseminate the results of your evaluation to the pipeline industry, inspectors, and the public.

Priority: CLASS II

Overall Status: Closed - Acceptable Action

Issued Date: 2015-02-10

Adopted Date: 2015-01-27

Overall Date Closed: 2020-07-16

Synopsis: There are approximately 298,000 miles of onshore natural gas transmission pipelines in the United States. Since 2004, the operators of these pipelines have been required by the Pipeline and Hazardous Materials Safety Administration (PHMSA) to develop and implement integrity management (IM) programs to ensure the integrity of their pipelines in populated areas (defined as high consequence areas [HCAs]) to reduce the risk of injuries and property damage from pipeline failures. An operator’s IM program is a management system designed and implemented by pipeline operators to ensure their pipeline system is safe and reliable. An IM program consists of multiple components, including procedures and processes for identifying HCAs, determining likely threats to the pipeline within the HCA, evaluating the physical integrity of the pipe within the HCA, and repairing or remediating any pipeline defects found. These procedures and processes are complex and interconnected. Effective implementation of an IM program relies on continual evaluation and data integration. The IM program is an ongoing program that is periodically inspected by PHMSA and/or state regulatory agencies to ensure compliance with regulatory requirements.

Ntsbnumber: DCA14SS002

Report Number: SS-15-01

Addressee Name: PHMSA

Addressee Status: Closed - Acceptable Action

Addressee Date Closed: 2020-07-16

Addressee Acronym: PHMSA

Addressee Organization Type: G-Federal Government

Communication Date: 2026-03-26

Communication Type: Recommendation Mention

Communication Contents: From the report “Atmos Energy Corporation Natural Gas Fueled Home Explosions and Fires, Jackson, Mississippi, January 24, 2024, and January 27, 2024” published on March 26, 2026: 1.7.2.2 Report on Pipeline Risk Models In 2020, PHMSA published a report highlighting the strengths and limitations of the different types of pipeline distribution integrity management risk models. Footnote: PHMSA published this report in response to Safety Recommendation P-15-12. Safety Recommendation P-15-12 is classified Closed—Acceptable Action. In the report, PHMSA reviewed four risk model types and evaluated the effectiveness of each type in supporting pipeline operator risk assessments and decision-making. PHMSA assessed the qualitative model, the relative assessment (index) model (relative risk model), the quantitative system and probabilistic model, and the probabilistic model. The report notes that quantitative and probabilistic models are more robust than qualitative and relative-risk models. PHMSA made several conclusions in the report, including: (1) Probabilistic risk models were a best practice for large, complex systems and systems lacking data because they were more versatile and provided greater capabilities for risk insights and decision making support than the other types of models. (2) Pipeline operators who continued to use relative-risk models should supplement personnel judgment (subject matter expertise) with as much pipeline physical attribute data (system data) as could reasonably be acquired over time. Footnote: The report noted that relative-risk models were best suited for small, less complex pipeline systems. (3) Pipeline operators should take ongoing actions to improve and update (system) data quality and completeness over time (PHMSA 2020). (See section 1.9.3.2 for more information on Atmos’s distribution integrity management risk model.)

Addressee Acronym: PHMSA

Addressee Organization Type: G-Federal Government

Communication Date: 2016-12-05

Communication Type: Official Correspondence

Communication Contents: We note that, in 2015, you held a risk-modeling workshop to address how operators may move beyond risk index models. Further, we understand that a guidance document will be developed and disseminated by AB in 2017. In 2015, we supported your plans to evaluate the safety benefits of the four risk-assessment approaches currently allowed by the gas integrity management regulations; however, your update does not provide specifics on how you evaluated the approaches, nor does it provide any information on how you will determine whether they produce a comparable safety benefit. Therefore, we request that you provide amplifying information on how you evaluated the safety benefits of the four risk-assessment approaches and how you reached your conclusions. Pending this information and our determination that these actions satisfy the intent of Safety Recommendation P-15-12, it is classified OPEN—ACCEPTABLE RESPONSE.

Addressee Acronym: PHMSA

Addressee Organization Type: G-Federal Government

Communication Date: 2020-07-16

Communication Type: Official Correspondence

Communication Contents: You previously told us that, on September 9 and 10, 2015, you held a risk-modeling workshop to address how operators can move beyond risk index models, when needed, to improve investigative and forensic capabilities and to enhance stakeholder engagement. Further, you established a risk-modeling working group that included industry and other stakeholders and that addressed perceived shortcomings in certain risk models. On March 6, 2020, you published the final report, Pipeline Risk Modelling—Overview of Methods and Tools for Improved Implementation, on your website. This report was based on the findings of your risk-modeling workgroup and considered the major types of pipeline risk models, as well as the effectiveness of each type in supporting risk assessments when applied to pipeline operator decisions. Specifically, the report discusses the following: • major types of pipeline risk models and the effectiveness of each type to supporting risk assessments, as applied to pipeline operator decisions. • potential threat types that could interact and guidance on evaluating their effect on contributing to pipeline failures. • various threats with interaction potential, as well as methods for incorporating threat interactions into risk models. • the completed PHMSA-funded project DTPH56-14-H-00004, which provides tools and techniques to account for interacting threats in risk assessments. We note that the report also evaluates the suitability of four basic risk-modeling approaches to support risk management decisions required by integrity management regulations. We further note that you have disseminated your evaluation to the pipeline industry, inspectors, and the public. These actions satisfy the intent of Safety Recommendations P-15-10 and -12, which are classified CLOSED--ACCEPTABLE ACTION.

Addressee Acronym: PHMSA

Addressee Organization Type: G-Federal Government

Communication Date: 2020-01-23

Communication Type: Official Correspondence

Communication Contents: As we pointed out in our discussion of Safety Recommendation P-15-10, we were aware that, on September 9 and 10, 2015, you held a risk-modeling workshop to address how operators can move beyond risk index models, when needed, to improve investigative and forensic capabilities and to enhance stakeholder engagement. Further, you established a risk modeling work group that included industry and other stakeholders and that addressed perceived shortcomings in certain risk models. Although you expected to develop risk-model guidance for operators by July 2017 that includes how to evaluate for interactive threats, you said the publication date for this guidance would be delayed until 2018. We note that you published your Pipeline Risk Modeling Report for public comment in the Federal Register on August 16, 2018. We further note you have completed the final report and included applicable public docket comments, and that you believe this report, when it is published, will be responsive to Safety Recommendations P-15-12 and -13. However, you are currently evaluating how the DOT’s new guidance on cost–benefit considerations will impact your publication plans. We are pleased with the progress you have made in response to these recommendations. Please notify us when you have published the report so we can assess whether it meets the intent of these recommendations. Pending publication of the report and our review, Safety Recommendations P-15-12 and -13 remain classified OPEN--ACCEPTABLE RESPONSE.

Addressee Acronym: PHMSA

Addressee Organization Type: G-Federal Government

Communication Date: 2018-02-21

Communication Type: Official Correspondence

Communication Contents: In your response to Safety Recommendation P-15-10, you described the September 9 and 10, 2015, risk-modeling workshop that you held and the work group that you established to address how operators may move beyond risk index models. You previously told us that, to satisfy Safety Recommendation P-15-12, you were developing a guidance document based on the risk modeling work group’s results that would be made available by an AB. We note from your current letter that you continue to develop this guidance. In our December 5, 2016, letter, we pointed out that this recommendation asks that you evaluate the safety benefits of the four risk assessment approaches currently allowed by the gas IM regulations; however, your August 17, 2016, update did not provide specifics on how you evaluated the approaches, nor did it provide any information on how you will determine whether the four risk assessment approaches produce a comparable safety benefit. Therefore, we asked you to provide information on how you evaluated the safety benefits of the four approaches and how you reached your conclusions. In your current letter, you responded that guidance development is based on input from the risk-modeling work group. We reviewed the group’s meeting minutes and we were unable to find any focused consideration of the four approaches or if they provide comparable safety benefits. Your plan to publish an AB will satisfy this recommendation if it provides a focused discussion in a single location of the four risk assessment approaches, and if they provide comparable safety benefits. The AB will need to describe the methods used to determine if the safety benefits from each risk assessment approach are comparable. Pending guidance with that information, Safety Recommendation P 15-12 remains classified OPEN--ACCEPTABLE RESPONSE.

Addressee Acronym: PHMSA

Addressee Organization Type: G-Federal Government

Communication Date: 2015-07-15

Communication Type: Official Correspondence

Communication Contents: We note that the upcoming modeling workshop discussed above will provide a public forum for gathering data that will assist you in developing guidance on risk assessment approaches. We support your plans to conduct an evaluation of the safety benefits of the four risk assessment approaches currently allowed by the gas integrity management regulations and to disseminate the results by July 31, 2016. Pending the completion of these actions as scheduled, Safety Recommendation P 15-12 is classified OPEN—ACCEPTABLE RESPONSE.

Addressee Acronym: PHMSA

Addressee Organization Type: G-Federal Government

Communication Date: 2020-04-20

Communication Type: Official Correspondence

Communication Contents: -From Howard R. Elliott, Administrator: PHMSA proposes closure of this recommendation. As discussed in PHMSA’s response to P-15-10, on March 6, 2020, PHMSA published a report titled “Pipeline Risk Modeling - Overview of Methods and Tools for Improved Implementation.” The report evaluates the suitability of four basic risk modeling approaches to support risk management decisions required by integrity management regulations.

Addressee Acronym: PHMSA

Addressee Organization Type: G-Federal Government

Communication Date: 2019-12-03

Communication Type: Official Correspondence

Communication Contents: -From Howard R. Elliott, Administrator: Our response to NTSB Safety Recommendation P-15-10 describes the steps PHMSA has taken to publish the report titled "Pipeline Risk Modeling - Overview of Methods and Tools for Improved lmplementation."10 PHMSA believes this report will meet the intent of this recommendation.

Addressee Acronym: PHMSA

Addressee Organization Type: G-Federal Government

Communication Date: 2019-04-01

Communication Type: Official Correspondence

Communication Contents: -From Howard R. Elliott, Administrator: Our response to NTSB Safety Recommendation P-15-10 describes the steps PHMSA has taken to publish the report titled "Pipeline Risk Modeling - Overview of Methods and Tools for Improved Implementation," also known as the "Pipeline Risk Modeling Report." PHMSA believes this report will meet the intent of this recommendation.

Addressee Acronym: PHMSA

Addressee Organization Type: G-Federal Government

Communication Date: 2017-11-13

Communication Type: Official Correspondence

Communication Contents: -From Howard R. Elliott, Administrator: PHMSA is currently drafting guidance to meet this recommendation. PHMSA notes that the NTSB requested amplifying information on how PHMSA evaluated the safety benefits of the four risk-assessment approaches and reached our conclusions. PHMSA's guidance development is informed in part by the input from the work group, based on presentations and team discussions. Meeting minutes (available at https://primis.phmsa.dot.gov/rmwg/meetings.htm) memorialize these discussions. The group has held meetings since late 2015 to develop and discuss guidance for operators on risk models, including the evaluation of interactive threats, which will be finalized by PHMSA and communicated to stakeholders. Due to extensive coordination, PHMSA now expects to publish guidance by April 30, 2018.

Addressee Acronym: PHMSA

Addressee Organization Type: G-Federal Government

Communication Date: 2015-05-12

Communication Type: Official Correspondence

Communication Contents: -From Timothy P. Butters, Deputy Administrator: The Pipeline and Hazardous Materials Safety Administration’s (PHMSA) mission is to protect people and the environment from the risks of hazardous materials transportation. We are committed to continual improvements to our oversight program to positively influence the safety performance of pipeline operators. PHMSA has a long history of cooperating and collaborating with the NTSB, and we take our responsibility to address all recommendations seriously. Integrity Management (IM) is a performance-based, process-oriented regulatory program developed by PHMSA in response to the Accountable Pipeline Safety and Partnership Act of 1996 (P.L. 104-304), the Pipeline Safety Improvement Act of 2002 (P.L. 107-355), and PHMSA’s oversight experience. Integrity management regulations supplement PHMSA’s prescriptive safety requirements and set systemic performance requirements for operators. IM is based on practices employed by many safety-oriented organizations, whereby safety is continually improved through an iterative process of collecting data, identifying and prioritizing risks, undertaking corrective actions, and assessing performance. We understand that successful implementation of performance-based systems for pipeline safety requires a significant operator commitment to the approach, a diverse set of skills possessed by the operator and regulator that extend beyond pipeline engineering, detailed information on pipeline system and operating conditions, and an understanding of the causes of incidents and near-incidents. For both operators and regulators, the heart of integrity management is to identify the most serious risks through an evaluation of system and incident data, to take data informed corrective action to address risk, and to evaluate program effectiveness and implement new measures based on ongoing assessments of the results. PHMSA is working to improve pipeline safety and the IM program through regulatory development and other means at our disposal. Our Notice of Proposed Rulemaking (NPRM) titled “Pipeline Safety: Gas Transmission,” updating gas transmission pipeline regulations, was recently sent to the Office of Management and Budget (OMB) for review. This NPRM will address many of the NTSB’s recommendations, and we expect it to help pipeline safety by both setting new requirements for operators to follow, and clarifying existing ones. PHMSA’s National Pipeline Mapping System (NPMS) Information Collection was published in the Federal Register on July 30, 2014. We expect the revised Information Collection to lead to improved positional accuracy and address the need for additional pipeline attribute information to support our internal risk models. We believe both of these efforts will be responsive to the NTSB recommendations made in their respective areas. In parallel with our rulemaking and information collection efforts, PHMSA utilizes a variety of non-regulatory approaches to improve pipeline safety and communications. Our public awareness, emergency response training, research and development (R&D), technical workshops, and enforcement programs have helped to advance pipeline safety. For example, since February 2014, PHMSA has conducted seven workshops and public meetings on technical topics such as R&D, cracking, class location, Safety Management Systems, and the National Pipeline Mapping System. PHMSA is also planning a risk-modelling workshop for the summer of 2015 to address the need for operators to move to more sophisticated risk models. Finally, pipeline operators, as owners of the pipeline infrastructure, are required to know and understand their pipeline system operating environments. PHMSA challenges operators to focus on performance and aim beyond the minimum compliance standards established through pipeline safety regulations, to ensure the safety of the public that lives and works around pipelines. Concur. PHMSA will conduct an evaluation of the safety benefits of the four risk assessment approaches currently allowed by the gas integrity management regulations and disseminate the results by July 31, 2016. The upcoming modelling workshop referred to in response to P-15-10 will provide a public forum for PHMSA to gather data to inform guidance on risk assessment approaches.

Addressee Acronym: PHMSA

Addressee Organization Type: G-Federal Government

Communication Date: 2016-08-17

Communication Type: Official Correspondence

Communication Contents: -From Marie Therese Dominguez, Administrator: On September 9-10,2015, PHMSA held a risk modeling workshop to address how operators may move beyond risk index models, where needed, to improve investigative and forensic capabilities, and to enhance stakeholder engagement. After the workshop, PHMSA established a risk modeling work group that includes industry and other stakeholders, to address perceived shortcomings in the application of certain risk models. The expected outcome of this work group is guidance on risk assessment approaches currently allowed by the gas integrity management regulations. This guidance will be communicated to stakeholders through an appropriate mechanism such as an advisory bulletin. PHMSA originally anticipated publishing guidance by May 31, 20 16; however, to allow for critical stakeholder involvement, as discussed during the workshop, we now expect to publish by July 31, 2017.

Addressee Acronym: PHMSA

Addressee Organization Type: G-Federal Government

Communication Type: Official Correspondence