PHMSA observes that severe flooding is the kind of unusual operating condition that can adversely affect the safe operation of a pipeline and require corrective action under the Pipeline Safety Regulations (49 CFR parts 190– 199). §§ 192.613(a) and 195.401(b).

In October 1994, major flooding along the San Jacinto River near Houston, Texas, resulted in eight pipeline failures and compromised the integrity of several other pipelines. Similar flooding has occurred along the Yellowstone River in the past few months.

While the cause of the accident is still under investigation, ExxonMobil Pipeline Company experienced a pipeline failure near Laurel, Montana, on July 1, 2011, resulting in the release of crude oil into the Yellowstone River.

—PHMSA notice

In the advisory notice, PHMSA urges pipeline operators to take the following actions to prevent and mitigate damage to pipeline facilities in areas affected by flooding:

• Evaluate the accessibility of pipeline facilities that may be in jeopardy, such as valve settings, which are needed to isolate water crossings or other sections of a pipeline.

• Extend regulator vents and relief stacks above the level of anticipated flooding, as appropriate.

• Coordinate with emergency and spill responders on pipeline location and condition. Provide maps and other relevant information to such responders.

• Coordinate with other pipeline operators in the flood area and establish emergency response centers to act as a liaison for pipeline problems and solutions.

• Deploy personnel so that they will be in position to take emergency actions, such as shut down, isolation, or containment.

• Determine if facilities that are normally above ground (e.g., valves, regulators, relief sets, etc.) have become submerged and are in danger of being struck by vessels or debris; if possible, such facilities should be marked with an appropriate buoy with Coast Guard approval.

• Perform frequent patrols, including appropriate overflights, to evaluate right-of-way conditions at water crossings during flooding and after waters subside. Determine if flooding has exposed or undermined pipelines as a result of new river channels cut by the flooding or by erosion or scouring.

• Perform surveys to determine the depth of cover over pipelines and the condition of any exposed pipelines, such as those crossing scour holes. Where appropriate, surveys of underwater pipe should include the use of visual inspection by divers or instrumented detection. Information gathered by these surveys should be shared with affected landowners. Agricultural agencies may help to inform farmers of the potential hazard from reduced cover over pipelines.

• Ensure that line markers are still in place or replaced in a timely manner. Notify contractors, highway departments, and others involved in post-flood restoration activities of the presence of pipelines and the risks posed by reduced cover.