A study issued in April 2016 by the INGAA Foundation, an arm of the natural gas transmission industry, stated that “land movement, particularly in variable, steep, and rugged terrain, can pose a threat to the integrity of a pipeline if those threats are not mitigated. Mitigation of Land Movement in Steep and Rugged Terrain for Pipeline Projects: Lessons Learned from Constructing Pipelines in West Virginia was prepared, “to educate and inform those in the pipeline industry about the threats of land movement and outline practical mitigative measures.” It was filed with FERC on October 31, though not by INGAA.

The study identifies number of critical items when mitigating land movement on pipeline rights of way (ROW), including:

  • The importance of identifying landslide and erosion hazards, and incorporating that information into the design, planning and construction phases of a project;
  • The critical role of route selection in identifying and avoiding hazards that may impact pipelines and ROWs;
  • The need to incorporate site-specific mitigation measures into the project planning process, to address threats to the pipeline and the ROW;
  • The association between land movement and surface and subsurface water in combination with changes in the local ground conditions from recent or historical changes in geologic conditions and/or construction-related activities;
  • Structural measures are also available to address unstable slopes, such as retaining walls, soldier piles, sheet piles, wire mesh systems, mechanically stabilized earth systems and other mechanical structures;
  • Consideration of the landslide and erosion processes, and the origin of the source(s) of water relative to the constructed pipeline ROW.

The susceptibility of landslides along the ACP route was highlighted in an August 23 filing with FERC by Dominion Transmission, Inc. in response to questions posed by the agency regarding potential disruption and harm that could occur within the George Washington and Monongahela National Forests. One of the pieces of information filed by Dominion was that the susceptibility to landslides along the ACP route through the National Forests is 98%, 33% of the route being categorized as having a Medium to High susceptibility for landslide incidences, and 65% of the route being estimated as having a High (or greater) susceptibility. For more on this, see ABRA Update 94 (August 25, 2016, article at the top of page 2).

Industry Study Warned of Threats to Pipeline Integrity
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