Falls Dam reconstruction using roller compacted concrete

The 53 hydroelectric facilities operated under Nova Scotia Power Inc. are being reviewed as part of the utility's comprehensive dam safety program to ensure compliance with the 'Dam Safety Guidelines' published by the Canadian Dam Association. The 70 year old Falls Dam, located in southwestern Nova Scotia, was placed in a 'high' consequence category based on the results of the review. The dam controls a drainage area of 68 square miles. The original structure consisted of a 40 foot high concrete gravity dam with two 10 foot wide stop-log gates and a 200 foot long earthfill embankment. The review indicated a need for additional spillway discharge capacity and greater stability. Five procedures were identified as having potential for upgrading the facility. After a review of the alternatives, it was decided that a 312 foot long free overflow spillway dam made of roller compacted concrete (RCC) would be constructed to replace the existing structure. Over a period of seven days of continuous operation some 1100 cubic yards of facing concrete and 4000 cubic yards of roller compacted concrete were placed. 5 refs., 2 tabs., 8 figs