(1) The grade of the top of pipe within the highway right of way shall comply with the applicable Design Standard for Underground Utility Encroachment.

(2) Where less than minimum cover is made necessary to avoid obstacles, the pipe should either be rerouted or protected with a casing or concrete slab acceptable to the department.

(3) Cover for pipelines carrying transmittants which are flammable, corrosive, expansive, energized, or unstable shall not be reduced below safety limits as specified in the appropriate industry standards and specifications.