The Pipeline and Hazardous Materials Safety Administration (PHMSA) has issued an advisory bulletin to remind owners and operators of natural gas and hazardous liquid pipelines of the potential for damage caused by earth movement from landslides and subsidence in variable, steep and rugged terrain and for varied geological conditions.

“These conditions can pose a threat to the integrity of pipeline facilities if those threats are not identified and mitigated,” PHMSA said.

In the notice, published in the Federal Register earlier this month, PHSMA advised operators to consider taking a series of actions to ensure pipeline safety, including identifying areas that may be prone to large earth movement, utilizing geotechnical engineers during design, construction and operation of pipelines, and developing design, construction, monitoring and mitigation plans for pipelines.

PHMSA said it was “aware of recent earth movement and other geological-related incidents/accidents and safety-related conditions throughout the country, particularly in the eastern portion of the United States.”

Events identified by PHSMA over the past three years included gasoline, crude oil, propane and natural gas spills as well as pipeline ruptures caused by flooding, soil erosion and landslides in five states.

Other notable recent events include an Energy Transfer Partners LP pipeline in Western Pennsylvania that slipped and exploded in September, likely because of a landslide. A landslide was also blamed for an explosion on Columbia Gas Transmission LLC’s Leach Xpress in June 2018.

Such incidents have the Mariner East and other pipeline projects facing additional scrutiny from lawmakers and regulators.