LANDSLIDE MAPPING AND HAZARD ANALYSIS FOR A NATURAL GAS PIPELINE PROJECT
The landslide dataset collected from the mapping was subsequently used as input to a qualitative hazard assessment, which began with determining the lateral extent, basal shear depth, pipeline proximity, and activity of each landslide within 100 m of the pipeline centerline. Based on information determined from this review, the field mapping classification was updated to a project specific classification system with three mechanisms (falls, slides, and flows) and multiple types of landslides for each mechanism.
Initial screening on whether a landslide posed a risk to the pipeline was based on the mechanism of movement and pipeline proximity. At this stage, landslides were either determined to pose no credible hazard and eliminated from further evaluation or determined to pose a credible risk and evaluated further. The next stage of evaluation involved considering movement scenarios for each of the landslide mechanisms and the consequence to the pipeline of such movement. Using these movement scenarios, the potential for pipeline rupture was determined based on the position of the pipeline relative to the slide combined with a determination of whether the slide was active or not.
The result of this evaluation was to identify those landslides that posed a credible risk to the pipeline. Where space was available within the right of way, rerouting was recommended as the preferred mitigation strategy. Engineered solutions will likely be required for remaining landslides where rerouting is not an option.