Tunnelling means the construction of any tunnel beneath the natural surface of the earth for a purpose other than the searching for or winning of a mineral
Tunnel means a subterranean passage made by excavating beneath the over burden into which a building worker enters or is required to enter to work;
Dewatering means the removal of water for construction activity. It can be a discharge of appropriated surface or groundwater to dry and/or solidify a construction site. It may require Minnesota Department of Natural Resources permits to be appropriated and if contaminated may require other MPCA permits to be discharged.
Dike means an embankment or ridge of either natural or man-made materials used to prevent the movement of liquids, sludges, solids, or other materials.
Perimeter means the fenced or walled area of the institution that restrains the movement of the inmates.