According to World Architecture News, the station will "...boost the British economy by at least £20bn, creating and supporting thousands of jobs and adding 10 per cent extra capacity to London's public transport network."
A project this size hasn't been seen in London for over 50 years, and fortunately building techniques have changed for the better. The building of the station is being carried out with
"...environmentally responsible construction methods, including the silent piling rigs and coffer dam to partially dewater the dock, minimise disruption to office occupiers, local businesses and residents.”
While pictures indicate a green roof on the Canary Wharf station, there has been controversy as to whether other stations will have green roofs also.
According to Building, in its 20 October 2008 article,
Cabe’s design review panel said the practice’s material for the proposed Isle of Dogs station was “largely illustrative,” and complained of a “lack of hardline drawings giving exact information”.
It said it was not convinced the scheme’s green roof could be achieved, asked for clearer detail on the predicted movement flow through the station, and said more work could be done to open up the park element of the scheme to visitors.
Although I haven't found any further updates on the controversy, London does have at least four additional designs for green roofs. More information can be found here.
This improvement to the underground system in London will provide not only improved quality of life inside the city, but also a better environment through green roofs.