St. Anthony Falls Navigation Project

St. Peter sandstone is a soft loosely bonded rock that disintegrates readily when subjected to flowing water. This type of foundation, encountered in the St. Anthony Falls project, called for careful geological investigating and testing. De-watering excavated areas required special precautions for the control of subsurface seepage. Deep seated steel sheet piling, wellpoint system and chemical grouting were adopted as essential construction safety measures. A type of structure was selected in order to assure that the foundation under and adjacent to the completed locks and dams would not be disturbed. Meticulous regulations of the pool levels within the metropolitan areas requires the use of control gates that will minimize interference with the operation of existing structures and utilities. Radiant heating and low pressure bubbler systems were adopted to keep the gates operable during cold weather periods. Railway bridge alterations made under sustained traffic required the coordination of planning and execution by the contractor, the operating agency, and the designing engineer.