IT’S York’s biggest “garage door” – and it’s set to save Christmas for thousands of York homes and businesses. It’s the Foss Barrier, on which work started 25 years ago. Mike Laycock reports

AT 9.30pm on Thursday evening, Paul Maw keyed in a password to a computer and a 16.5 tonne barrier slowly slid down like a giant garage door to block the River Foss at its confluence with the River Ouse.

Then a series of mighty pumps began pumping water out of the Foss into the Ouse at the rate of up to 30 tonnes of water per second.

For the sixth time in this wettest of years, the Foss Barrier and pumping station had swung into action, prompted by the Ouse’s rise to more than 2.8 metres above normal summer levels.

With more heavy rain predicted today and in coming days, the Environment Agency’s complex looks set to prevent Christmas being ruined for hundreds – maybe thousands – of households by the misery and devastation of flooding from the River Foss, Tang Hall Beck and Osbaldwick Beck.

Paul, a barrier operator, says that until the barrier was built in the late 1980s, more properties in York used to be flooded by the Foss and the two becks than by the Ouse. The problem was that floodwater from the Ouse used to surge up the already-swollen Foss and becks, causing them to overtop their banks.

The £3.34 million barrier project, which started in 1987, is an engineering marvel which has solved that problem time and again, most dramatically in November 2000 when the Ouse reached its highest levels in centuries and the pumps had to run for ten consecutive days. It was again of vital importance in September this year, when river levels were only half a metre lower and the pumps ran for almost a week. Colin Atkinson, a senior emergency planning advisor for the agency, says the pumping station would still work even if the area was hit by a massive power cut. Two huge diesel-powered generators at the heart of the complex can create enough electricity to power four of the eight pumps.

Paul stresses that while the pumps’ capacity is huge, the extra water pumped into the Ouse is still only a fraction of the total flow of 300 tonnes a second, and therefore cause Ouse floodwaters only to rise by a centimetre or so.

When the pumps are operating, someone must be on site at all times, and so Paul and agency colleagues, including Richard Boaz and Ian Westmoreland, are now resigned to coming in on an emergency rota over the Christmas period to help keep York flood-free.