£10m overhaul begins on city's barrier against tides

The Environment Agency is spending £10m upgrading Hull's tidal barrier, which protects 17,000 properties in the city.

The barrier, one of only three of its kind in the country, was built in 1980 in response to the last severe tidal flooding to hit the city in 1969.

Workmen have started preparing for a programme of work that will see the installation of a new drive mechanism, which lifts and lowers the barrier.

Every bolt and rivet on the 212-tonne steel gate will be checked and replaced if necessary, while the agency has also submitted a planning application for larger buildings at the base of the barrier's two towers to house the new engine and equipment.

The work can only be carried out in a three-month window when low tides are predicted.

The first phase is expected to be completed in July, with workmen returning to finish the project over the same three-month period next year.

Peter Holmes, the agency's area flood-risk manager for North and East Yorkshire, said: "It's vitally important to protect Hull from flooding from the Humber.

"We estimate if the barrier wasn't there then about 17,000 properties would be at greater risk of flooding.

"It's the first time we have done this and we are making sure it can keep going into the future for another 25 to 30 years."

The barrier protects the city from tidal surges, which occur when low pressure in the north of Scotland causes winds which push great volumes of water south along the East Coast.

The effect is magnified in river estuaries, particularly when combined with spring tides.

The barrier, which is usually operated by two people, is used on average about 12 times a year and can be deployed within half an hour of a flood warning.

The agency gets information from a storm tide warning service run by the Met Office.

Hull Council estimates 118,000 properties are at risk from river flooding and in 1969 many homes and businesses were ruined by a tidal surge on the River Hull.

This led to the Hull Tidal Surge Barrier Act of 1973, and the opening of the barrier seven years later.

There have been no major breaches since, and the barrier was credited with preventing a serious incident in 2005 when it resisted one of the highest tidal surges in decades.

The city discovered it was also vulnerable to surface water flooding two years ago after an unprecedented deluge devastated homes and livelihoods in large parts of Yorkshire and the South West.

Latest figures show that 8,790 domestic properties in Hull were affected, with about 4,500 households forced to move out. Last month 431 households were still living in temporary accommodation. The number of victims may continue to rise as a result of secondary flooding, or rising damp.

Since January 2008, 910 properties have been vacated after secondary flooding, although 592 have since been reoccupied.

In the East Riding 112 households are still in temporary housing.

Hull Council's cabinet agreed last month to extend council tax relief for another financial year for victims. The extended relief will cost the authority about £120,000 – but will be covered by a £265,000 surplus from a grant given to the council by central government for flood relief.