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Special projects

Some construction or rehabilitation projects are so complex that they demand the creation of innovative, custom solutions. Queformat is often called upon to work on such projects. Here are just a few examples.

PONT-ARNAUD DAM, CHICOUTIMI RIVER
During the torrential rains of July 1996, the Chicoutimi River flooded the clayey plains, tore a 14-metre-deep, 80-metre-wide breach in the Pont-Arnaud dam. To close the massive gap and bring the waters of the Chicoutimi River back to their original bed, Queformat was mandated by Hydro-Québec to design a new rock-fill dam.

The challenge was to stabilize the (very sensitive) clay block in a straight line, excavate a canal in the rock-bed of the left bank of the Chicoutimi River and erect a rock-fill structure across the gap, which was blocked up with disturbed soil and debris, all in under four months.

MACHU PICCHU
The Machu Picchu power station in Peru was built in 1965 and expanded in 1985. Situated on the Rio Vilcanota, it produces 90% of the electricity consumed in the province of Cuzco. In February 1998, a debris flow flooded into a tributary of the Rio Vilcanota, burying its confluent under nearly 50 metres of sediments. The debris—which contained blocks over five metres in diameter—and the lake that formed as a result of the disaster swallowed the power station and the other facilities completely.

Hydro-Québec International asked Queformat to help re-start the power station. As part of its mandate, Queformat developed and oversaw an exploratory program the bedrock and the 50 metres of sediments that had accumulated over the power station. The company then developed various rehabilitation scenarios for the power station.

Furthermore, an exploratory visit was carried out along the 20 kilometres of the Rio Vilcanota tributary, between its mouth and source, the Nevado Salcantay, a glacial plain located at an altitude of over 5,000 metres. This visit allowed Queformat to assess the risk of a similar event occurring in the future.

PALAIS DES CONGRÈS DE MONTRÉAL EXPANSION PROJECT
The expansion of the Palais des Congrès required 15 or so metres of soil to be excavated. Invited to submit a proposal for materials testing, Queformat specialists were intrigued by the client's decision to use a diaphragm wall as a temporary support for the walls of the excavation site—a costly and time-consuming method.

Following several discussions, the client gave Queformat permission to complete the geotechnical investigation that had been undertaken by other consultants, by means of bore-holes. The results obtained from in situ tests and thorough analyses demonstrated that so long as the client made sure to strictly control retention and runoff water, it could support the soil using a wall. 

Using Queformat’s recommendations, the client carried out the excavation project efficiently, completing the work three months ahead of schedule and cutting costs by some hundreds of thousands of dollars. This came as no surprise to the experts at Queformat. They did, however, astound their competitors from the firm that committed the grave error of doubting the accuracy of their analyses.