WORK has started on a £13 million upgrade of York's Foss barrier and pumping station, even before planning permission has been granted.

But Environment Agency chiefs say they still don't know why the control room - meant to be watertight - was inundated by floodwaters on Boxing Day, forcing them to raise the barrier.

Homes and businesses along the course of the Foss and its tributaries were flooded after the defences were overwhelmed by the sheer volume of water coming down the river.

The pumping station was designed to be able to pump about 30 tonnes of water per second from the Foss into the Ouse and it was unable to deal with an estimated 35 tonnes per second that evening.

The upgrade, which will include the installation of eight more powerful replacement pumps, is set to increase its capacity so it can handle at least 40 tonnes per second.

The first stage of the scheme is the construction of a temporary concrete platform alongside a flood wall on the edge of St George's Field car park, on which a temporary control room will be constructed.

Planning permission will be needed for this but an agency spokeswoman said this was still pending, adding: "However we have, with the agreement of City of York Council, started work on the platform to ensure we maintain progress of work."

She said work on the platform would take about five weeks to construct and the agency was still working to its programme to complete the works by November next year.

The agency has said previously that an investigation into the leak of water into the control room was due to be completed by the end of March.

But the spokeswoman said yesterday: "We are still waiting for the investigation report to be completed.

"This has taken longer than expected because there was a period of time when we couldn’t start the investigation until the water levels had dropped at the barrier, so this delayed our work slightly. As soon as we have the final report we’ll share it with you."

Howard Hawley, who recently committed to buying a property in Hungate - whose underground garage was flooded by the Foss - said he was concerned by the delay.

He believed the problem was either mechanical, electrical or human, or the design was simply overrun, and it should not take three months to say which was responsible.

"If, as I suspect, it was human error then the people of York need to be assured that it will not happen again and that systems have been put in place," he added.