Measurement of Deformations in Buried Pipeline

Since 1986, measurements of deformations have been made on a section of large‐diameter buried natural gas pipeline in northern Alberta. Precise conventional survey techniques are used to measure the deformations. Three‐dimensional translation components of the deformations are determined through the use of a survey network, while three‐dimensional rotation components of the deformations are determined by making special types of measurements with a one arc second theodolite. The monumentation required for this project, as well as the instrumentation, observational procedures, and analysis procedures used to determine the translations and rotations are described. The results indicate that part of the section of buried pipeline moved a significant amount in the downhill direction during the period from 1986, when the first survey was carried out, to 1989. This prompted a decision to excavate and rebury the entire section of line, and to continue monitoring deformations. Further remedial work, such as attempting to stabilize the slope or rerouting the pipeline, might be considered in the future.