Power Station Construction in Canada's Wilderness
Jürgen Kronenberg, Putzmeister AG
The ongoing energy development of Hydro-Québec is part of a $2 billion project undertaken by SEBJ (Société d'énergie de la Baie James). For Hydro-Québec, SEBJ has been instrumental in the development of a very rich hydroelectric area via numerous power stations installed since the 1970s. The new Eastmain-1 hydroelectric power plant located on the Eastmain River near James Bay is designed to generate 480 MW of electric power for Hydro-Québec. This was preceded by extensive negotiations with the Cree Indian clans resident in the region.
The enormous project includes a powerhouse, a main dam across the Eastmain River, the spillway on the right bank of the river, and 33 dikes for reservoir closure. The construction of the project's complex was broken down into five major contracts, awarded independently via open public bids.
The largest of all structures being built is the 50 m tall, 125 m long and 55 m wide powerhouse where three huge turbines will generate the power. This surface powerhouse, built into a rocky hill, is on the left bank of the Eastmain River. By the time the water exits through the tailrace, it will have dropped over 60 m from the water intake. This head, combined with the flow, develops kinetic energy that causes the turbines and generators to turn, producing electricity.
In particular, the major $108 million powerhouse, penstocks, and water intake project were started in the spring of 2004 under the direction of Canadian contractor Aecon-Hochtief JV. The Aecon Group is one of Canada's largest publicly traded construction companies, and the group is 49%-owned by German construction giant Hochtief. Upon completion in early 2006, the reputable general contractor will have pumped over 46 000 m3 of concrete. This amounts to about two-thirds of the total 68 000 m3 needed for the entire project.
Aggregates of granite, a little water and low cement content
Instead of typical 125 mm pipe, 150 mm diameter was needed throughout the delivery system in handling the extremely harsh concrete mix supplied by the on-site batch plant. The brutal mix comprises crushed granite at 38 mm wide yet an inconceivable 100 mm long. Due to the abrasive mix, high pressures, and distances involved, Putzmeister ZX pipes and couplings are also being used. In addition, with generally lower water/cement values, the concrete for many constructional elements have hardly any free water and the cement content is often significantly reduced in order to reduce the hydration heat.
Concrete mixing trough as an additional "buffer"
The second trailer pump serves as backup because cold joints are absolutely forbidden or the powerhouse would be structurally deficient. Consequently, in case of an equipment malfunction, the second pump can finish a pour.
Mr. Chryssolor said, "We basically have to almost duplicate equipment needs because of our remote location 15 hours away from Montreal. With 600 men on a job, we can't afford down time. Fortunately, no major problems have resulted to-date, and the equipment has performed to our demanding expectations."
From April to November 2004, concrete work for the powerhouse took place. Two 24 m tall placing boom towers were anchored with bolts and had to be precisely mounted in specified locations so no cold joints would interfere with the flow of water upon project completion.
The two placing booms first provided full coverage to place concrete for both the walls of the huge turbines and the powerhouse structure itself.
In November, the two towers were moved to handle the intake structure. This time, they were supported by 4.5 m x 4.5 m x 1.2 m high poured concrete mats, and the placing booms still provided ample reach to all concrete placing areas.
Especially noteworthy is the placing boom's Multi-Z boom configuration, which proved exceptionally maneuverable in working under the low roof of a temporary overhead steel structure. The structure was specially built so construction could continue during the frigid winter months.
Aecon-Hochtief is also handling the horizontal concrete work for the penstocks. The three enormous penstocks are concrete-lined conduits excavated in the rock to channel water from the reservoir to the powerhouse turbines and are designed to maximize the head (drop in level).
During a peak period in summer 2004, nearly 2400 workers were housed in dormitories. Work is carried out in alternating shifts, each lasting 42 days. There are then ten days free. Similar to a mini-town, the site offers a variety of services such as cafeteria, hair salon, convenience store, post office and library along with indoor and outdoor recreational facilities. Once the project is complete, the approximate 1,3 km2 workcamp will be dismantled and transported to another job site.
Besides building the concrete intensive powerhouse, other construction projects on site are also utilizing various Putzmeister models. This includes a electric-powered trailer pump being used by Norascon-Hebert S.E.N.C. joint venture, two companies well established in Québec. The unit is competently placing concrete for all incline work associated with the penstocks.
In addition, a belt conveyor was utilized for placing concrete on the main dam across the Eastmain River. The contractor, Hamel Construction took full advantage of the conveyor's special functionality to place unusually tough mixes and other aggregates such as sand, gravel and rock with ease.
For construction of the numerous dams, various trailer-mounted pump models were utilized for shotcreting by Norascon-Hebert and also by Construction Injection E.D.M. Inc., who were sub-contracted by La Compagnie de Constuction et de Développement Crie Ltée in Montreal. In addition, a diesel-powered rotor/stator pump handled injection grouting for EBC Inc..
Even the Dynajet high-pressure cleaners were on-site working six months for Neilson Inc. of Québec City. Next to the dam, two Type 500 models sprayed water at high 500 bar pressures to thoroughly clean selective areas of rock before concrete placement was possible.
As of spring 2005, the entire Eastmain-1 project was 66% complete. Plans are for the facility to be operational by late 2006.
Self-confident First Nations peoples
After years of dispute over the dam project in their Reserve at James Bay, several clans of the Canadian Cree Indians, such as the Mistissini, the Nemaska and the Waskganish, agreed to a negotiation compromise between the provincial government of Québec and their chieftains in February 2002, after an agreement was reached among the clan members in the nine villages of the Reserve.
According to this agreement, the Cree people will receive a total of $3,4 billion over a period of 50 years as compensation for the construction of dams at the Eastmain and Ruppert Rivers, and as compensation for the flooded areas. The Cree people want to use the money to develop the economy, the infrastructure and living space. The negotiated compromise was strongly disputed, especially among the younger members of the clans.
Today, there are around 1 million "First Nations" or "Inuit" people. They are believed to have reached the country via a land bridge from Siberia to Alaska. The first contact between Europeans and the First Nations people occurred around 1000 years ago when Vikings settled predominantly in Newfoundland. Due to its rich supply of oil and gas, Canada is today one of the leading energy exporters in the world. However, huge amounts are spent on using natural energy resources in their own country.
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