PARSC 007 – Recommended Practice for Cleaning Pipelines for Abandonment

June 2021

Executive Summary

Pipeline abandonment occurs when a pipeline is permanently removed from service at the end of its useful life, which may consist of abandonment in place or excavation and physical removal of the pipeline. The need for understanding possible long-term concerns associated with pipeline abandonment has become increasingly prevalent in industry. The cleaning of a pipeline for abandonment is an important factor to consider during development and implementation of an abandonment program.

posed the question of “How Clean is Clean?” as a guide for industry to consider both the condition inside an abandoned pipeline and the potential for migration of any materials out of an abandoned pipeline [1,2]. In 2007 the NEB established the Land Matters Consultation Initiative (LMCI) to consider land related matters with input from various stakeholders including industry members and land owner groups [3], and in 2010, the NEB commissioned a literature review to summarize known technical issues related to pipeline abandonment and to identify knowledge gaps to be addressed in future studies [4, 5]. This review identified several knowledge gaps and recommended topics for future studies,

General cleaning guidelines were published within the 1996 Discussion Paper on Technical and Environmental Issues and the Pipeline Abandonment Research Steering Committee (PARSC) has recently published an industry report summarizing existing practices and technologies for cleaning; however, currently there are no published standards that define acceptable levels of cleanliness for decommissioned or abandoned pipelines [6]. A key recommendation from this Discussion Paper was to pursue development for a set of criteria for allowable levels of residuals in an abandoned pipeline, to establish an acceptance level below which residuals remaining in a pipeline would pose no detrimental impact to the environment if integrity of the abandoned pipeline was compromised.

In the context of permanent abandonment, it has previously been acknowledged that corrosion will even eventually result in through-wall perforations of the pipeline over a significant time [1, 4, 5]. These perforations could result in the abandoned pipeline allowing water or soil to enter the pipe through the pipe wall perforations and then under certain circumstances, flow to lower elevations, with the pipeline acting as a water conduit. Water and soil flowing through an abandoned pipeline could carry residual contaminants through the pipeline, depending on the level of cleaning performed prior to abandonment. Additionally, even without water flow along the abandoned line, once the abandoned pipeline is perforated an opportunity exists for any residual internal contaminants to be exposed to the surrounding soil and groundwater. Therefore, a systematic cleaning program development is recommended as part of a thorough pipeline abandonment program.

Final Report