Project Description

The dam site is located on the Sturgeon River approximately 16 km north of Sturgeon Falls in Northern Ontario. It was constructed in 1921 by Abitibi Power for hydroelectric power generation. Ontario Hydro purchased the site in 1935. In the mid 1980’s the main dam and the north channel dam were replaced using reinforced mass concrete gravity structures. The powerhouse underwent rehabilitation to increase its stability by constructing concrete tailrace piers and installing 47 post tensioned rock anchors, 6 anchorages for the upstream side of the powerhouse and 41 for the tailrace piers, and some contact grouting.

The bedrock beneath the structures was found to be a granitic gneiss with no apparent adverse geological features. Field investigations included bedrock and concrete sampling. Piezometers were installed to monitor uplift conditions for the powerhouse. Nondestructive ultrasound concrete and borehole camera surveys were reviewed. Underwater dive inspection findings for steel pile tips supporting the tailrace deck on an inclined bedrock surface were reviewed. An inspection of structural concrete, bedrock and seepage conditions was conducted. A stability review included a variety of loading conditions including normal and flood hydraulics for the headwater and tailwater levels, uplift, OBE and MDE earthquakes and ice loading. The IDF and PMF characteristics were reviewed to develop an incremental hazard rating.

The findings and the recommendations of the Phase 1 Dam Safety Assessment outline priorities for a Phase 2 field investigation and monitoring program.