PLANS to replace sewage tankers with barges on the River Ouse at Ely are still in the pipeline, Anglian water said this week.

A decision over the scheme was due at the end of last year. But almost six months later Anglian Water said it was still looking into the costs and environmental issues surrounding the project, while more work had to be carried out on how tides in the fast-flowing river might affect the project.

“We learned a lot from the river trials carried out last year and the various meetings that we’ve had since then,” a spokesman said. “It’s early days, but all of this has helped us understand a lot more about how we might be able to use the river.

“We knew that the fast tides and the significant variation in the levels of the tide were going to pose challenges, and it has been interesting to see how these could be dealt with.

“There is more work to be done to understand exactly what the operating window on the river would be, given tides, bridge heights and daylight hours – and whether this window would allow us to transport a sufficient quantity of sludge by using barges on the river.”

Anglian Water is also looking at whether the non-tidal Relief Channel, which runs between Denver and Saddlebow, could be used instead of the tidal river.

“As there is no lock at the Kings Lynn end, we would need to explore the possibility of converting the existing sluice to allow for lock facilities,” the spokesman added.

“However, all of these options add significant capital and operating costs.”

Anglian Water believes the move would cut the number of lorries travelling to and from its plant at Clenchwarton, near King’s Lynn, from 60 to 10.

Tugs towing 400-tonne barges would bring sludge from the treatment works beside the river off Cresswells Lane, on the outskirts of Ely, to moorings near Lynn.

The sludge, which would be piped to the Clenchwarton treatment plant, could then be turned into biogas or fertliser. A trial carried out last September was a success, with the 40-mile journey taking two days. Major rivers through the Fens were once the main cargo-carrying routes.