Design of Parallel Pipelines

Parallel pipelines are becoming more common in urban areas as space within existing roadways becomes limited and as demands exceed existing pipeline capacities. This paper provides a summary of the technical information used to design new pipelines in parallel with existing pipelines. Of primary concern are separation distance, dead and live loads during construction, and failure and subsequent risk of erosion. Sufficient separation distance is required between parallel pipelines to maintain stability of the supporting soil around the existing pipeline and to minimize the potential for cross contamination. During construction, dead and live loads on existing pipelines must be considered when evaluating constructability and estimating the required construction work zone width. Failure of a pipeline and erosion from discharged fluids may undermine adjacent pipelines. A project currently in design is used to illustrate the design of a new pipeline to be constructed parallel to existing pipelines. The location of the new pipeline and required construction width were an important element of the Environmental Impact Report.