Existing comment:
American Falls De-watered:
Concern over the occurrence of major rockfalls like those of 1954, and their effect on the appearance of the American Falls, led to one of the most dramatic man-made accomplishments in Niagara's history.
The ambitious shutting down of the Falls in 1969, gave the United States and Canada valuable information which has served as a guide to prevent further geological related events and disasters.
A cofferdam was constructed between the east-end of Goat Island and the American mainland. The entire American Rapids channel and falls were de-watered, a feat never performed by man before and seldom by nature.
From June to November 1969, a complete and detailed geologic investigation was made.
The purposed of the study were threefold: (1) determine if erosion of the American Falls could be controlled, (2) determine if removal of the rock debris at the base of the American Falls was desirable, (3) determine if other measures were necessary to preserve the beauty of the Falls.
The de-watering study furnished geologic and engineering information and an understanding of conditions at the American Falls that had been unattainable previously.
An additional authorization was made in 1970 to include a study of Luna Island and Terrapin Point viewing areas. These investigations revealed unstable sections and instruments were installed to monitor rock movement and to provide warning of future massive rockfalls.
In 1955, the Cave of the Winds walk below the Bridal Veil Falls was permanently altered. Originally, a large ledge of Lockport Dolostone below the crest of Bridal Veil directed water away from the face of the cliff and allowed people to walk directly behind the Falls.
This ledge, approximately 30 feet deep, was judged to be unsafe and was removed by blasting. In spite of this, the Cave of the Winds walk is still a spectacular trip that leads to the base of Bridal Veil Falls, but not longer passes behind it.
In 1972, remedial work was performed at Luna Island and the Bridal Veil Falls. This falls was de-watered and steel dowels, rock bolts, and cable tendons were installed in an intricate pattern to strengthen and stabilize the area. A series of drain holes were drilled to relieve the hydrostatic pressure of ground water. |