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Case Study: Niagara Tunnel breaks barriers

Case Study: Niagara Tunnel breaks barriers

In an ambitious project, an engineering landmark takes shape 140 m under the Niagara Falls in Canada. When finished, the project will increase output by about 1.6 billion kWh, enough to supply renewable energy to 160,000 homes. Aaron Rosland writes about an upcoming landmark in Canada's powerscape.
 
The Niagara Falls, straddling the international border between the states of Ontario, Canada, and New York, USA, is a valuable source of hydroelectric power. The Sir Adam Beck Hydroelectric Power Stations is a complex of two hydro-generation stations in the city of Niagara Falls, Ontario, the first of which started producing power in 1922. Together,
the two stations generate 1,926 MW, making it one of Canada's largest power generation parks. The complex plays a key role in Ontario's Long-Term Energy Plan, a vision document presented in 2010 that aims at building a clean, modern and reliable electricity system for tomorrow. The province is replacing coal fired plants with renewable energy projects from water, wind, solar and bio-energy. It has already helped create 20,000 jobs across the province. The Sir Adam Beck Stations Complex is operated by Ontario Power Generation (OPG), a public company wholly owned by the Government of Ontario. OPG is responsible for appro­ximately 70 per cent of the electricity generation in the Province of Ontario, Canada.

OPG's Niagara Tunnel Project recently completed the drilling phase.  

Adam Beck I Station contains 10 generators. Adam Beck II contains 16 generators and it is this station (first commissioned in 1954) that is undergoing major modi­fication in the form of the Niagara Tunnel Project in order to improve its generation output. Currently, water is diverted from the Niagara River above the falls through underground pipes. A reservoir has been created that permits the holding of water, diverted during the night, for use during the day. The Niagara Tunnel, expected to be in operation by late 2013, will comple­ment the existing water delivery system and overall will increase the efficient use of the power of the Niagara River.

The Niagara Tunnel is 10.4 km long, 14.4 m in diameter and runs under the city of Niagara Falls. Its capacity will be 500 cu m (17,660 cu ft) of water per second, and this will increase the generating capacity by 150 MW and will help bolster the current power system, which is close to exceeding its capacity during peak months.

The Government of Ontario has invested C$985 million in Niagara Tunnel Project, making it the largest renewable energy project of its type under construction anywhere in the world. In the construction phase itself, the project has created more than 400 full-time jobs and brought approximately $1 billion in economic benefits to the region.

Niagara Tunnel will be a source of pride not only as an engineering feat, but also as a practical solution for meeting Ontario's energy demands through clean sources. The Niagara Tunnel will allow Ontario Power Generation to increase output at the Sir Adam Beck generating stations by about 1.6 billion kWh. This me­ans power for approximately 160,000 homes. Ontarians now, and in the future, will benefit from the hard work. With minimal maintenance costs, all this energy will be generated year-in, year-out for a hundred years or more.
 
The Wonder that Is Big Becky
In August 2005, OPG appointed Strabag of Austria as the contractor to build the Niagara Tunnel Project at a cost of C$600 million. After designing the Tunnel, Strabag selected The Robbins Co of Solon, OH (US) to design, manufacture and deliver a new 14.4 m (47.5 ft) diameter high performance, state-of-the-art main beam hard rock tunnel boring machine (TBM) to be used for the excavation of the tunnel. To meet the aggressive con­struction schedule, the TBM needed to be supplied as ready-to-bore within a 12-month period after the con­tract was awarded to Robbins in September 2005. 

The engineers shipped in machinery parts from all over the world to the job site at Niagara Falls. They bro­ught parts in by road, by sea, and by rail. And then they built
the largest hard-rock TBM in the world – an incredible 150 m (500 ft) in length, 14.4 m (47.3 ft) in height and weighing more than 4000 tonne, That's more than 800 elephants.
The new Robbins HP main beam TBM was affec­tionately named “Big Becky” in honour of Sir Adam Beck, pioneer and advocate of Canadian hydroelectri­city. For her sheer size, Big Becky more than deserves her name.
 
The Process of Drilling
Digging a tunnel 14.4 m wide, at a depth of up to
140 m, and for a total distance of 10.2 km was the major challenge of this project but Big Becky has just completed this engineering marvel. In the process, this massive un­dertaking has connected the City of Niagara Falls to the Sir Adam Beck Complex, creating about
1.6 million cu m of rock and debris. Big Becky operated about 140 m below the ground, and as a result, the vibrations from the machine were hardly felt on the surface.

The 14 m (45 ft) diameter cutting head is equipped with dozens of rotating discs that carved up the rock in front of the drill. The rock then fell through open slots in the cutter head, and would land in collector bins, from where a conveyor belt below would whisk it all away.
As Big Becky carved through the rock, the crew sealed up the walls of the tunnel behind her with concrete to keep the interior smooth. This lets the rushing water of the Niagara River pass through without obstructions. All this work is designed to keep the tunnel operational for over 100 years.
 
The Milestone Breakthrough
Becky drilled forward at about 4 m (about 13 ft) per hour, and had been at work for the Niagara Tunnel Project since 2006. On 13 May 2011, at approximately 12:34 pm, Becky finally broke through the last few met­res of rock and reached the end of its course. The cere­monial breaking through took place before a large num­ber of government officials, OPG executives, workers, media and invited guests. The breakthrough occurred at 10,143.026 m.
With the drilling phase over, one of the major cha­llenges in the project has been crossed. The Niagara Tunnel is now well on its way to be commissioned by its target completion date in 2013.
 
Looking Forward
This major milestone brings the Province of Ontario one step closer to increasing the supply of clean, ren­ewable power and an important achievement as Ontario continues to transform and modernise its electricity system. The state's energy plan is creating thousands of good jobs, cleaning the air, and keeping the lights on in homes and businesses. By tapping into Ontario's original electricity source-Niagara Falls-the province is help­ing to create a better future for the local economy and Ontario families.

As part of the Open Ontario plan, the government is moving Ontario from coal dependency to a clean, mod­ern and reliable energy economy that creates jobs. Energy is one of the engines of the economy and employs more than 95,000 Ontarians. Recent investments to modernise the system are helping to create and support jobs and opportunities for people and communities acr­oss the province. Ontario's landmark Green Energy and Green Economy Act, 2009 is projected over three years to support over 50,000 direct and indirect jobs in smart grid and transmission and distribution upgrades, rene­wable energy and conservation.
 
 
How did Becky get her name?
According to tradition, a Tunnel Boring Machine needs a name before work begins. The students in Mr Dyck's Grade 6 class at Port Weller Public School in St Catharines wanted to enter the naming contest for the giant drill. They knew the important role Sir Adam Beck had played in developing hydroelectricity in Ontario. However, they couldn't name the TBM after him because, like ships, all TBMs have female names. So the class converted Adam Beck's last name to “Becky” and added the descriptor “Big” to create their award-winning entry.
 
The author is Counsellor (Commercial-Ontario), International Marketing Centre-India, Canadian High Commission.

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