Short Term Hydrotechnical Risk Control Measures Used During the Implementation of Watercourse Pipe Replacement Projects

摘要

Pipeline watercourse crossings are designed according to the best available industry/technical standards at the time of construction. Older pipeline systems were typically installed without the benefit of modern hydrotechnical engineering practices with little or no allowance for ongoing fluvial processes. The level of protection at specific crossings can deteriorate such that a relatively small flood (i.e. 1:10 year) can pose a significant integrity threat. The hazards associated with maintaining an existing crossing may not be acceptable for the continued safe operation of a pipeline; therefore, a pipe replacement may be required. The designing, planning, permitting, funding, contracting and construction of any pipe replacement option can require considerable time to implement. In most watercourses in Canada and the United States this means that the pipeline at risk, but not in an emergency situation, will likely go through at least one spring freshet and/or other seasonal peak flow event(s) prior to implementation of the pipe replacement project. Four examples of short term risk control measures are discussed for river crossings in and around central and northern British Columbia, Canada.