Contra Dam

On May 6, 1960, Verzasca SA was formed to construct the dam as the center-piece of the Verzasca Hydroelectric Complex. Construction of the dam began in 1961. The dam was designed and its construction supervised by Lombardi & Gellaro Ltd. Because the Contra Dam is at a lower elevation compared to other Swiss dams, warmer weather allowed construction to be carried out year-round. To divert the river and prepare a dry work-site for the dam, cofferdams were constructed, one of which redirected the river through a diversion tunnel with a capacity. As the river can have flows much higher than the tunnel's capacity, this was accepted as a risk by engineers. Excavation of the right side of the dam had to be expanded due to unforeseen weathered rock and designs were altered within 15 days. and in September 1965, the reservoir was full and the dam completed. As many as 25 shocks occurred a day. and no damage was found. After refilling, the shocks decreased and an "equilibrium" was believed to have been reached, one that did not respond to variations in water load. Another large shock occurred several years after filling. By 1971, there were no more seismic shocks around the dam or reservoir. No known detailed geological studies were conducted prior to construction of the dam and several faults are known to exist in the area. ==Specifications==

Dam The Contra Dam is a concrete slender arch dam with a height of and crest length of . The dam is wide at its base and wide at its crest. The dam structure contains of concrete and the structure itself has a surface area of . The dam is slender in design and its horizontal arches are in an elliptical shape. The horizontal curvature of the dam decreases from the center of the dam towards its abutments and the curvature from the center of the arches increases from the crest down to the foundation. The thickness is constant with the exception of where the dam is received by its abutments; here it is thicker to reduce pressure on the rock, which can accept pressure of . Vertically, the thickness of the dam increases from the crest down to the foundation and has a slight curve from the center towards the crest. This helps alleviate tensile stress for when the reservoir is not only full but empty. The dam's outlet works consist of two discharge pipes, capable of releasing up to each. One discharges into the original diversion tunnel and another is located at the base of the dam and discharges into the river valley below. Spillways The dam has two spillways, each located on the structure, near its abutments on either side which have a maximum discharge capacity of . Each spillway contains six fixed-crest weirs that are wide. From each opening, the water flows down a single chute to a flip bucket at the bottom of the spillway. The flip buckets dissipate and deflect the water towards the center axis of the valley below. The spillways were later modified to improve releases and function by increasing the size of the piers and adding additional lateral deflectors near the crest. Power plant The dam supports a 105 MW power station that contains 3 × 35 MW Francis turbines and generates an average of 234 GWh annually. Water from the reservoir at above sea level is transferred to an underground power station downstream at above sea level, affording a maximum hydraulic head of . The power plant can discharge up to of water which exits via a tailrace tunnel into Lago di Verbano. ==In popular culture==

The opening scene of the 1995 James Bond film GoldenEye featured Bond jumping off the dam. The stunt was performed by British stuntman Wayne Michaels. The jump was voted as best movie stunt of all time in a 2002 Sky Movies poll. The dam doubled as the fictional Arkhangelsk Chemical Weapons Facility located in the northern Soviet Union during the Cold War. The climax scene of the Indian Bollywood movie Dhoom 3 was shot at this dam. In October 2022, an artificial climbing wall built on the dam hosted an event called Red Bull Dual Ascent, the first competition climbing event in a multi-pitch format. == Notes and references ==