220 CMR, § 111.03
Unless otherwise ordered by the Department in any particular case, no street, place or way subject to the provisions of 220 CMR 111.00 shall be constructed over a high-pressure gas main except where it is necessary for said street, place or way to cross said main. Whenever such crossings are required, they shall be made as nearly as practicable to an angle of 90E to the center line of said main. The main shall be enclosed in a casing and constructed in a manner which meets the requirements of the specifications issued by the American Petroleum Institute - API RP 1102 (7th ed.), Steel Pipelines Crossing Railroads and Highways, except that the minimum distance from the top of the casing to the used surface of the road shall be four feet six inches and the casing shall extend beyond the edges of the pavement or used surface of the street, place or way where there is no pavement a distance of not less than 25 feet or to the line of the right of way for the street, place, or way, whichever is the lesser. In cases where said right of way is not defined, the casing shall extend 25 feet beyond the edges of the pavement or the used surface of the street, place or way where there is no pavement. The Department will ordinarily grant a reduction in depth of cover limitations provided that all such construction be in accordance with the specifications for excavation and backfill set forth in 220 CMR 111.04, and the Department will also grant a variance from the requirement of casing if the pipeline facility can be adequately safeguarded and such installation is made in accordance with 220 CMR 111.04.
220 CMR, § 111.03