As the first anniversary of work on the U.K.’s 225-km London-Birmingham high-speed railroad (HS2) is reached, news of a major bentonite leak of more than 1,500 cu m at the project’s first tunnel has revived opposition to the project.
The leak occurred as the first two of 16 panels forming the diaphragm wall were being excavated near an 80-m deep emergency and ventilation shaft about 35 km west of London. It is the first of five shafts on the 16-km Chiltern twin tunnels, being built by the Align joint venture of Bouygues Travaux Publics, VolkerFitzpatrick and Sir Robert McAlpine.
“While we regret the loss at this location, monitoring has not identified any adverse effects on the aquifer or on water supplies, and the Environment Agency and water company have raised no concerns," an HS2 spokesman said.
A similar slurry loss followed at panel 9 that September. The leaks were stemmed by ground treatment, but not before a section of an aquifer was polluted. Align is one of four joint ventures handling the line’s main civil work, valued at around $17 billion.
Align mobilized two tunnel-boring machines earlier this year, while the first of the remaining eight TBMs will set off “in the coming months,” says Mark Thurston, CEO of HS2 Ltd. Nearly a third of the line’s $56-billion target price, including land and real estate purchases, has been spent, and around $17.5 billion contracted.