WAC 480-75-640
Depth-of-cover survey.
For pipelines constructed after April 1, 1970, each pipeline company must conduct a depth-of-cover survey in its pipeline rights of way every five years to ensure the minimum depth-of-cover as required by subsections (1) and (2) of this section has been maintained for the entire pipeline. In areas subject to erosion and subsoiling, the survey must be conducted every three years.#
(1)Unless specifically exempted in this section, each pipeline company must bury all pipe so that it is below the level of cultivation. Except as provided in subsection (2) of this section, the pipe must be installed so that the cover between the top of the pipe and the ground level, road bed, river bottom, or sea bottom, as applicable, complies with the following table:#
LocationCover(inches)For normal excavationCover(inches)For rock excavationIndustrial, commercial, and residential areas3630Crossings of inland bodies of waterwith a width of at least 100 ft. from high water mark to high water mark4818Drainage ditches at public roads and railroads3636Deepwater port safety zone4824Any other area3018#
(2)Cover less than the minimum required by subsection (1) of this section may be used if:#
(a)It is impracticable for the pipeline company to comply with the minimum cover requirements; and#
(b)The pipeline company provides additional protection equivalent to the minimum required cover.#