There are strict regulatory requirements for pipeline construction at river and stream crossings. The requirements for monitoring, surveillance and maintenance of existing crossings on the other hand are limited to a few lines in Section 10 of CSA Z662-99.
Systematic procedures for assessing stream channel stability are not readily available to the operators of pipelines. As a consequence, many monitoring and inspection programs focus more on detecting exposures than on preventing them.
In this paper, the AEC Pipelines Ltd. approach to monitoring river and stream crossings is reviewed and discussed. The program involves application of basic geomorphic concepts and use of aerial photographs to define channel characteristics at crossing sites and to determine which crossings may be subject to future channel instability or erosion problems. From these in-house evaluations, decisions are made to either proceed with more in-depth assessments by river engineering specialists or continue with routine aerial and ground surveillance. As part of the overall program, procedures for completing routine channel surveys and a checklist of data to be gathered during regular reconnaissance trips have been developed.