All crossings of the roadbeds of the trunk highways shall be made by boring inside a casing or carrier pipe, or by jacking, unless this procedure is modified in the special provisions of the permit for construction. The auger shall not lead the casing or carrier pipe by more than one inch. Open trenching shall be restricted to the area from five feet beyond the shoulder to the right-of-way line except as modified in the special provisions of the permit for construction.
When pipes with bells or flanges are installed, the crossings of the roadbeds of trunk highway shall be made by boring inside a conduit, as provided in the preceding paragraph, of jacking a conduit of sufficient diameter to permit threading the carrier pipe through it.
All voids caused by jacking or boring shall be filled by pressure grouting. The grout material shall consist of a sand-cement slurry of at least two sacks of cement per cubic yard and a minimum of water to assure satisfactory placement.
The underground utilities shall be so installed as virtually to preclude any necessity for disturbing the roadbeds to perform maintenance operations.
Underground installations shall be accomplished without damaging or destroying the principal root structure of specimen trees.
MS s 161.45
August 6, 2012