How a Pipeline Project Comes Together
Almost 2 million miles of pipeline carries natural gas around the country as of 2016, according to the U.S. Department of Transportation. Construction on new pipelines takes place to connect new drilling sites to the processing facilities that distribute the energy source, but how does it all come together?
The rush to move natural gas to markets places pipelines too close to homes, with construction taking place in backyards, farms, pastures, and right at the mailboxes of residents throughout the country. Let’s study the process of pipeline construction.
After all federal and state level permits are approved and easement agreements or eminent domain condemnations are completed, the process of pipeline construction can begin. Crews flag the boundaries of all locations where construction activities will take place. The flags mark the extent of the temporary construction zone surrounding the pipeline right-of-way (ROW), as well as the staging and storage areas.
Cutting the ROW
After the equipment is accessible in the staging area, work will begin to clear cut the pipeline right-of-way. Large trees are stockpiled or hauled off, while the branches and tree tops are placed into piles and burned. A stump grinder then removes the remaining tree stumps in the ROW.
Excavating the Trench
The trench for the pipeline is dug after the ROW is cleared of trees. Sandbags are placed within the trench to restrict water flow and to support the pipe.
Stringing and Assembly
When the trench is completed, pre-coated segments of pipe (usually 40 feet in length) are transported from stockpiles in the staging area to the ROW. Pipes are laid above ground beside the trench or within the trench on top of supportive sandbags in steep terrain. The pipe sections will then be welded together and sandblasted, and the weld joints will be coated with epoxy to prevent corrosion. Finally, the weld joints will be inspected with x-ray to ensure their quality. Connected lengths of pipe can then be lowered into the trench.
Dealing with Obstacles
Pipelines cross existing roads, highways, streams, rivers and wetlands. Typically, pipelines are constructed underneath these obstacles by either boring for shallow depth or using horizontal directional drilling (HDD) for deeper placement. Each obstacle requires a unique method and order of operations.
Testing and Restoration
After the pipe is inspected, the trench is filled in. Before completing the project, the pipeline integrity must be verified using hydrostatic testing. After this, the surface of the ROW is seeded and fertilized, and above-ground markers are placed along the pipeline path. The land is then returned to its natural state.
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