Boris Johnson tries to save park from supersewer

Boris Johnson has urged Thames Water to move work on its £3.6billion "supersewer" in order to prevent a popular park being turned into a building site.

In a letter to the firm, the Mayor of London warns that the 20-mile long tunnel could spoil residents' enjoyment of the King Edward VII Memorial Park, "a heavily-used section of the Thames Path" in Wapping.

Thames Water plans to construct the tunnel, broadly along the route of the river, to collect millions of tonnes of sewage discharge triggered by rainfall. It says 39 million tonnes of untreated waste flows into the river a year as the Victorian sewer system cannot cope.

Campaigners fear work at the park could last for up to seven years. It could include drilling an access shaft or "concreting over" the grass to run lorries and cranes to the foreshore.

In a joint letter, the Conservative Mayor and Dee Doocey, the Liberal Democrat chairwoman of the London Assembly, said: "King Edward VII Memorial Park is an important amenity for people who live in this area."

The Mayor joins about 4,000 Londoners, celebrities such as Dame Helen Mirren and Lee Hurst, and Tower Hamlets council in opposing the plans. He said a nearby outdoor activity centre could also be "compromised".

The letter highlights two alternative sites identified by local campaigners and the council, one housing a concrete plant in nearby Butcher Row and another on the south bank of the Thames at Chambers Wharf.

Mr Johnson writes: "We ask that Thames Water review these alternatives to assess their feasibility, costs and benefits and show how they compare to the current preferred option."

Emma Dunsire, of the Save KEMP campaign group, said: "Boris Johnson's support is a great achievement for us. Now it is up to Thames Water to listen and, most importantly, respond. So far they have let us down."

Thames Water has warned there are "no easy answers" in Wapping, where its current overflow discharges more than 784,000 tonnes of sewage a year.

The letter was addressed to Richard Aylard, Thames Water's sustainability director, who said today: "We welcome the Mayor's approach and will be responding positively.

"We have started looking at alternatives proposed by the Save KEMP group and will prepare the feasibility report requested by the Mayor. The point of our public consultation is to listen. We will continue to listen to Londoners' views to inform our plans, on which no final decisions have been taken yet."