PR350-174515-R01 Guidance on Excavation and Backfill in Areas of High Axial Strain and Stress

Excavation and backfill of in-service pipelines in areas of geohazards could face some unique challenges. The buried pipelines could be subjected to moderate to high levels of longitudinal/axial strains and stresses at the time of excavation. Operators need to make decisions on when and how to excavate and backfill, which can have impact on the public safety, environment, safety of the personnel working on the site, and pipeline operations. Industry-wide guidance or best practice does not yet exist.

This report provides guidance for excavation and backfill procedures in the areas of geohazards and addresses site stability and pipeline integrity for the pipeline segments already or potentially under high axial strain and stress. The guidance covers recommendations on three key work areas: preparation, excavation, and backfill.

The guidance can be used as a reference by pipeline operators and contractors when carrying out excavation and backfill in areas of geohazards. Alternatively, elements of the guidance could be incorporated into existing company procedures as appropriate. Even with known gaps in this subject area, the adoption of the recommendations in this guidance should lead to improved safety and integrity of pipelines.