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NTSB ADVISORY
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National Transportation Safety Board
Washington, DC 20594

January 3, 2011

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NTSB ISSUES URGENT SAFETY RECOMMENDATIONS AS A RESULT OF
PRELIMINARY FINDINGS IN SAN BRUNO PIPELINE RUPTURE
INVESTIGATION; HEARING SCHEDULED FOR MARCH

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The National Transportation Safety Board today issued seven
safety recommendations, six of them classified as “Urgent,”
as a result of its investigation into the pipeline rupture
and explosion that killed eight people and destroyed 37
homes in San Bruno, Calif., on September 9, 2010.

The recommendations were issued to address record-keeping
problems that could create conditions in which a pipeline is
operated at a higher pressure than the pipe was built to
withstand, although it is not known at this time if that is
what happened in the San Bruno accident. The urgent
recommendations call on pipeline operators and regulators to
ensure that the records, surveys, and documents for all
pipeline systems accurately reflect the pipeline
infrastructure as built throughout the United States so that
maximum safe operating pressures are accurately calculated.

As detailed in an investigative update the NTSB issued on
December 14, 2010, investigators found that although the
records of the pipeline operator, Pacific Gas and Electric
Company (PG&E), indicated that the pipeline in the area of
the rupture was constructed of seamless pipe, it was
instead, at least in part, constructed of longitudinal seam-
welded pipe. In addition, some of the seams of this section
of pipeline were welded from both the inside and the outside
of the pipe, while others were welded only from the outside.

The NTSB is concerned that the seam-welded sections may not
be as strong as the seamless pipe that was indicated in
PG&E’s records. Because it is critical to consider all of
the characteristics of a pipeline in order to establish a
safe maximum allowable operating pressure (MAOP), the NTSB
believes that these inaccurate records may lead to
potentially unsafe MAOPs.

To address this issue, the NTSB issued three safety
recommendations, two of which were classified as urgent, to
PG&E asking the utility operator to do the following: 1)
Conduct an intensive records search to identify all the gas
transmission lines that had not previously undergone a
testing regimen designed to validate a safe operating
pressure (urgent recommendation); 2) Determine the maximum
operating pressure based on the weakest section of pipeline
or component identified in the records search referenced
above (urgent recommendation); and 3) If unable to validate
a safe operating pressure through the methods described
above, determine a safe operating pressure by a specified
testing regimen.

The NTSB is also concerned that other pipeline operators may
have discrepancies in their records that could potentially
compromise the safe operation of pipelines throughout the
United States. Because of this, the NTSB has made an urgent
recommendation to the Pipeline and Hazardous Materials
Safety Administration (PHMSA) to expeditiously inform the
pipeline industry of the circumstances of the San Bruno
accident and investigative findings so that pipeline
operators can proactively implement any corrective measures
for their respective pipeline systems.

“While it may seem like a small paperwork error, if
companies are basing operating pressures on inadequate or
erroneous information contained in their records, safety may
be compromised,” said NTSB Chairman Deborah A.P. Hersman.
“We believe this safety-critical issue needs to be examined
carefully to ensure that operators are accurately gauging
their risk and that pipelines are being operated at
pressures no higher than that for which they were built to
withstand.”

The NTSB also directed three of the urgent recommendations
to the California Public Utilities Commission (CPUC), which
regulates PG&E’s pipeline operations as well as all
intrastate pipeline operations within California.  CPUC was
asked to ensure that PG&E “aggressively and diligently”
search documents and records to determine which pipeline
segments had not previously gone through a testing regimen
to determine a safe operating pressure and to provide
oversight of any testing conducted by PG&E if the document
and records search cannot be satisfactorily completed. CPUC
was also asked to immediately inform California intrastate
natural gas transmission operators of the circumstances of
the San Bruno accident so these operators can likewise
proactively implement any corrective measures for their
pipeline systems.

Additionally, the five Members of the NTSB voted to hold a
fact-finding hearing as part of the investigative process.
“This accident has exposed issues that merit further
attention and have implications for the pipeline
infrastructure throughout the country,” said Chairman
Hersman. “The hearing will gather additional factual
information for the investigation, and will also provide the
pipeline industry, state and federal regulators, and our
citizens with an opportunity to hear more about this
accident and important safety issues as the investigation
progresses.”

The two-day en banc hearing, which will be chaired by NTSB
Chairman Hersman and webcast at www.ntsb.gov, will be held
on March 1-2, 2011, at the NTSB’s Board Room and Conference
Center, 429 L’Enfant Plaza, S.W., Washington, D.C. The
hearing is open for public observation and free to attend;
no registration is required.  The agenda, including a list
of technical witnesses called to testify, will be publicized
several weeks prior to the proceedings.

SAFETY RECOMMENDATION LETTERS TO:

Pacific Gas and Electric Company: http://go.usa.gov/rWz

Pipeline and Hazardous Materials Safety Administration:
http://go.usa.gov/rWJ

California Public Utilities Commission:
http://go.usa.gov/rWS

RELATED INFORMATION:

Investigative Update issued on 12/14/10:
http://go.usa.gov/rWj

Preliminary Report issued on 10/13/2010:
http://go.usa.gov/rWD

Launch of investigation: http://go.usa.gov/rWW

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NTSB Media Contact: Peter Knudson
peter.knudson@ntsb.gov
(202) 314-6100

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