Does not include interest on capital investment, or capital construction after 1977. Where thaw-stable soils were found, the pipeline was buried in the conventional manner. In areas of thaw-unstable soils, and where heat from the oil in the pipeline might cause thawing and consequent loss of soil foundation stability, the pipeline was insulated and elevated above ground by means of a unique support system. Specially designed vertical supports were placed in drilled holes or driven into the ground.
Heat is transferred through the walls of the heat pipes to aluminum radiators atop the pipes.
The pipe is underlain with a layer of fine bedding material and covered with prepared gravel padding and soil fill material, in a ditch from 8 ft. to 16 ft. Zinc ribbons, which serve as sacrificial anodes to inhibit corrosion of the pipe, are buried alongside the pipeline. The Atigun pipe replacement section, 8.5 miles in length, has four magnesium ribbon sacrificial anodes installed. The zinc anodes act like grounding rods to safely return these currents back to the earth, reducing the risk of damage to the pipeline. In areas of thaw-unstable soils calling for elevated pipeline construction, but where the pipeline had to be buried for highway, animal crossings, or avoidance of rockslides and avalanches, the line was insulated, to protect the permafrost from the heat of the pipeline, and buried.