Sayano-Shushenskaya Dam

Speculation

The official RusHydro assessment was deemed overly optimistic by the opposition. The dam, which has no major flood control structures upstream, must bear the brunt of spring freshets, and due to a snowy winter and late thaw, in the first week of June 2010 the amount of spring flood water influx was about twice the normal (peaking at 9,700 m³/s on 5 June and expected to stay around 7,000 m³/s throughout the second and third weeks of June). Due to the August 2009 accident, only 2 out of 10 turbines were operable and capable of routing only 690 m³/s of water. Consequently, most of the water influx into the reservoir must be drained through a poorly designed spillway, which previously had already suffered extensive damage as a result of spring floods in 1985 and 1988. As of 8 June, drainage through the spillway was roughly 5,000 m³/s. While it would be possible to increase the spillway drain to 7,000–7,500 m³/s, such an operation was previously deemed unsafe to the structure,^] and could result in further erosion of the dam's already weakened foundation even as the reservoir continues to fill. The damage would occur by direct impact of the falling water to the spill well (which, once its concrete slab lining were destroyed, would expose and erode the dam's bedrock support) as well as by intense vibrations created by the waterfall, which the concrete dam, lacking steel reinforcement, is not designed to withstand for prolonged periods. To date, only one section of the bypass spillway had been completed, and was capable of routing only 2,000 m³/s of water, meaning that the main spillway, probably already worn and torn from the 2009 winter's heavy ice deposition on the dam, must continue to be operated for some time before repairs will be possible.

This situation has led some of the local population to petition for controlled draining of the reservoir and deconstruction of the dam, since the consequences of the dam's failure, should it occur, would be catastrophic. The resulting flood wave, which could be from 50 to 200 m high near the breach and moving at up to 200 km/h, would destroy the downstream Maynskaya HPP in a matter of minutes; the nearby town of Sayanogorsk would be flooded in under half an hour, and the heavily populated area including Abakan and Minusinsk (altogether more than 200,000 people)—within 40 minutes to several hours. After reaching the Krasnoyarskaya HPP further downstream, the flood wave would rise its reservoir by roughly 10 m and spill over its dam, destroying the power plant machinery. If that dam should fail too (the possibility of which exists in this scenario), the resulting mass of water could wash away the city of Krasnoyarsk and its suburbs, drowning or displacing their population of over 1,000,000.


On 17 August 2009 at 8:13 AM, the hydro-electric plant suffered a catastrophic accident that caused flooding of the engine and turbine rooms, and two 711 MVA electric generators to explode underwater as a result of a short circuit. All other machinery was damaged to some extent, with only four hydro-aggregates ultimately recoverable; the remaining six required replacement. As of 10 September 2009, 75 people, including 1 pregnant woman, were confirmed dead, while one person was still listed as missing forty days after the disaster

Power generation from the station ceased completely following the incident, with the resulting blackout in residential areas being alleviated by diverting power from other plants. Aluminium smelters in Sayanogorsk and Khakassia were completely cut off from the grid before power supplies were replaced using alternative power sources. Russia warned that in the longer term it might lose up to 500,000 tons of aluminum output due to the power shortage, and called for accelerating the construction of the Boguchanskaya hydroelectric power station to replace lost generating capacity.

The accident caused an oil spill with at least 40 tonnes of transformer oil released, spreading over 80 km (50 mi) downstream of Yenisei.^[31][34]
The plant restarted operations on 24 February 2010, while repairs were complete by November 2014. According to Russian Energy Minister Sergei Shmatko the rebuilding of the engine room alone would cost $1.2 billion.
Dam subcontractor Gidroelectroremont's chief accountant has been accused by the Khakassia police of embezzling 24 million rubles from the funds allocated by RusHydro for repairing the dam.