Installing a pipeline is much like an assembly line process, with sections of the pipeline being completed in stages. First, the path of the pipeline is cleared of trees, boulders, brush, and anything else that may prohibit the construction. Once the pipeline’s path has been cleared sufficiently to allow construction equipment to gain access, topsoil from both the permanent and temporary easement is removed and stockpiled along the edge of the temporary easement, taking steps to avoid compaction during removal and stockpiling. Tops soil may also be referred to as A or Ap horizon, the soil layers at the surface. On agricultural land where clearing is not necessary, topsoil removal is the first construction activity. Sections of pipes are then laid out along the intended path—a process called “stringing” the pipe. These pipe sections are typically from 40 to 80 feet long and are specific to their destination— that is, certain areas have different requirements for coating material and pipe thickness.
After the pipe is in place, trenches are dug alongside the laid-out pipe. These trenches are typically 5 to 6 feet deep. In certain areas, however, including road crossings and bodies of water, the pipe is buried deeper. Soil from trenching is stockpiled separately from the topsoil stockpiles, again taking steps to avoid compaction. Once the trenches are dug, the pipe is assembled and contoured. This includes welding the sections of pipe together into one continuous pipeline and bending it slightly, if needed, to fit the contour of the pipeline’s path. Coating is applied to the ends of the pipes (the coating applied at a coating mill typically leaves the ends of the pipe clean, so as not to interfere with welding), and the entire coating of the pipe is inspected to ensure that it is free from defects.