Wednesday, August 31, 2011

NTSB Cites 4 SCADA Related Findings in San Bruno Disaster

Yesterday the National Transportation Safety Board (NTSB) held a public meeting about the results of their investigation of the 2010 San Bruno, CA pipeline explosion/fire. At the same time their web site posted a synopsis of the yet to be officially released report on the investigation. That synopsis lists 28 separate findings that resulted from their investigation; four of which specifically address SCADA related issues. Those findings are:

• PG&E lacked detailed and comprehensive procedures for responding to a large-scale emergency such as a transmission line break, including a defined command structure that clearly assigns a single point of leadership and allocates specific duties to supervisory control and data acquisition staff and other involved employees.

• PG&E's supervisory control and data acquisition system limitations contributed to the delay in recognizing that there had been a transmission line break and quickly pinpointing its location.

• The 95 minutes that PG&E took to stop the flow of gas by isolating the rupture site was excessive.

• Use of automatic shutoff valves or remote control valves along the entire length of Line 132 would have significantly reduced the amount of time taken to stop the flow of gas and to isolate the rupture.

Additionally there were three control system recommendations that the NTSB is making to the Pipeline and Hazardous Material Safety Administration (PHMSA) out of the 12 PHMSA recommendations. Those recommendations are:

• Require operators of natural gas transmission and distribution pipelines and hazardous liquid pipelines to ensure that their control room operators immediately and directly notify the 911 emergency call center(s) for the communities and jurisdictions in which those pipelines are located when a possible rupture of any pipeline is indicated. Â [Supersedes Recommendation P-11-2]

• Require that all operators of natural gas transmission and distribution pipelines equip their supervisory control and data acquisition systems with tools to assist in recognizing and pinpointing the location of leaks, including line breaks; such tools could include a real-time leak detection system and appropriately spaced flow and pressure transmitters along covered transmission lines.

• Amend Title 49 Code of Federal Regulations 192.935(c) to directly require that automatic shutoff valves or remote control valves in high consequence areas and in class 3 and 4 locations be installed and spaced at intervals that consider the factors listed in that regulation.

Additional information on the rationale and reasons for these findings and assessments will be available when the full final report is published in the coming weeks.

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