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Engineering Prosperous Futures | Article

The Central Artery/Third Harbour Tunnel Project, also known as the Big Dig, is one of America's most challenging geotechnical jobs. The Big Dig, the nation's most complex and costliest highway project, was completed in 2007. The cost was originally estimated at $14.8bn. However in 2013 the actual cost was made public and stood at a staggering $24bn.

The Central Artery in Boston was erected in 1953 and had six lanes to accommodate 75,000 vehicles daily.  In the years that followed, the network had to accommodate over 200,000 vehicles a day, resulting in traffic jams, wasting fuel and slowing down economic growth in certain parts of the city.

The Big Dig project was set up to relieve congestion across Boston, replacing the out of date Central Artery road, closing the division between the North End, Waterfront neighbourhoods and the busy economic city of Boston.

The overall project can be split into two main construction jobs. The first was to take the existing Central Artery (an elevated six-lane highway) and replace it with an extended subterranean highway with a 14-lane two-bridge crossing of the Charles River at the northern end.

Second was to extend the Massachusetts Turnpike, south of downtown Boston, through a tunnel under South Boston and Boston Harbour to Logan Airport (Boston's Central Artery).

When construction ended in 2007, criticism of the project came from all angles. However, since the completion of the Big Dig, downtown Boston has been opened up for the first time in 50 years. People are now beginning to agree that Boston's huge 'super-project' has been a huge success.

With congestion and excess traffic now a thing of the past, the economic benefits of the 'Big Dig' are beginning to shine through. Southwest Airlines have shown economic growth; the presence they now have at Logan International Airport is a direct result of how the Big Dig has improved the movement of goods in the area.

Not only has the Big Dig improved the economy of surrounding areas, it has also improved the aesthetics of Boston as a city. The build and re arrangement of landscape has given space for other projects such as the Greenway, a chain of parks and greenery that takes advantage of the 15 acres of land that is now available. Downtown Boston has become more accessible, putting money back to areas that had once been forgotten.

Some of the challenges faced during the Big Dig have impacted on many geotechnical projects successfully delivered in the UK by Alan Wood & Partners. Although methods will be adapted to meet the challenges of different circumstances, the key principles of the Big Dig remain.

Alan Wood & Partners successfully delivered a contamination remediation on the Colwick Industrial Estate in Nottingham. The Cowlick Industrial Estate has great history in manufacturing, and has housed companies such as Trent Concrete, one of the largest prefabricated concrete businesses in the United Kingdom. The Colwick Industrial Estate was originally conceived as an inland port to Hull and eventually the North Sea.

Being an inland port, the estate had large areas that were used for bulk fuel storage, serviced by a network high pressure pipelines from the North Sea. Since the recent decommissioning of these fuel storage facilities, the area has been subject to numerous phases of Geo-Environmental investigation by Alan Wood & Partners. These identified significant hydrocarbon contamination of the underlying near surface soils and groundwater, resulting from major historic leaks and spillages of hydrocarbons. The underlying groundwater is in direct hydraulic continuity with the nearby River Trent.

Alan Wood & Partners have provided their client, City Estates with specialist advice on the most effective ways of remediating the site prior to its sale. This was achieved by undertaking Phase 1 Desk Studies followed by targeted Phase 2 Intrusive investigations. The data from these investigations were utilised to provide ground water and human health detailed quantitative environmental risk assessments (DQRA).

Alan Wood & Partners successfully negotiated with the Planners and the Environmental Agency.

Since the Geo-Environmental investigation, City Estates have drawn up proposals to transform the land into a high-quality, mixed-use development.

The proposals will see the land on the site brought back into use, much to the benefit of the area.

This includes the decontamination and clean-up of the site, a new Sainsbury’s supermarket, a family restaurant and pub, a fast food restaurant, a nine-pump petrol station with a car wash, extensive landscaping, improved roads and pedestrian/cycle links and the creation of up to 1,000 new jobs.

Alan Wood & Partners deliver unrivalled expertise in the disciplines of environmental science, environmental engineering, engineering geology, foundation engineering and geotechnics. Their specialists work globally, providing geotechnical and geoenvironmental consulting services.

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