Right-of-Way and Pipeline Monitoring in Permafrost: The Norman Wells Pipeline Experience

Abstract

Enbridge Pipelines (NW) Inc. (Enbridge) owns and operates a 323.9 mm outside diameter crude oil pipeline from Norman Wells, Northwest Territories, Canada to Zama, Alberta, Canada (Norman Wells Pipeline). The first of its kind in North America, this pipeline, completely buried in discontinuous permafrost, is approximately 869 kilometres in length. The pipeline, designed to operate at ambient temperatures, was constructed during the winter seasons of 1983–1984 and 1984–1985 and began operations in April 1985. Enbridge (formerly Interprovincial Pipe Line (NW) Ltd.), under various regulatory terms and conditions, is required to monitor and report the effects of pipeline construction and operations associated with the environment and right-of-way. The company has been an active participant in joint research and monitoring working groups consisting of various departments of the Government of Canada, Government of Northwest Territories, and other agencies. Over the past seventeen years, Enbridge has developed a monitoring and surveillance program that ensures the safe operation of the pipeline and protection of the environment. Any significant issues arising from the monitoring program result in mitigative actions based on engineering assessments. Furthermore, Enbridge is mandated to inform the appropriate agencies of issues resulting from the monitoring program. This paper will focus on the terrain and geotechnical monitoring programs initiated by Enbridge over its years of operation of this pipeline and will discuss topics including operations and maintenance activities key to pipelines installed in discontinuous permafrost, condition of the pipeline, and the on-going terrain and slope monitoring program.