Efforts ensure special places have a future

Apr 5 2008 by Tony Henderson, The Journal

Environment Editor Tony Henderson on the scale of the task to tackle flood risk.

HEXHAM has been hit by flooding for more than 200 years. After the Northumberland town suffered in 1993, 94, 95 and 2000, and with climate change threatening regular repeats, something had to be done.

But the task turned out to be the most complex flood protection project ever undertaken in the North East.

Yesterday, £7.6m and three years of work later, the scheme was declared operational by Environment Agency chairman Sir John Harman.

The Hexham scheme has highlighted how natural waterways running through and under settlements – which are a major reason why they were established in the first place – can remind everyone that they are still there.

Newcastle, with its Hidden Rivers project, used artworks to mark waterways such as the Pandon, Lort and Skinner burns which are culverted under the city.

At Hexham, the town is dissected by the Cockshaw, Halgut and Wydon burns, above and below ground.

In heavy rain and storm conditions, the waterways can flood.

Environment Agency North East flood risk and operations manager Ian Hodge says: “There could be very fast- flowing water through the town, and before this protection scheme there was a risk to around 150 properties and also to life and limb.

“This scheme was the most complex we have done in the North East because of its urban situation and the need to ensure that businesses and people could continue to go about their everyday lives while the work was carried out on their doorsteps.

“There were also health and safety issues – we had to make sure that people didn’t fall down holes in the ground.”

One of the main problems in Hexham was that the natural courses of the Cockshaw and Halgut burns were not adequate to deal with storm flows.

What made the situation worse was that the burns came together in an 80-year-old culvert under Alexander Place, which could not cope with storms.

“At the start of the project, as the agency tried to work out the best cost-effective scheme, it drew up a list of 35 options. It chose a combination of channel deepening and widening, raising the height of flood walls, new water diversion tunnels and upstream storage.

“It was a mosaic of defences,” says Ian.

Another aim was to seek environmental benefits on top of the practicalities of flood defence.

Water quality was improved in the burns, and concrete bottoms of above-ground channels were taken out to be replaced with more attractive cobbled surfaces.

Alexander Place junction was dug up to expose the culvert and 500 metres of new underground tunnel was built, with a flood diversion chamber.

“It was a huge job,” says Ian.

Four large steel pipes were driven under the Newcastle-Carlisle railway line. Because the track could not be dug up or closed, the work had to be done overnight during Christmas.

The main environmental bonus came when the agency bought the old, disused Wydon reservoir from Northumbrian Water on a hill to the south of the town.

The plan is that, during storm conditions, flow from the Wydon Burn can be diverted into the reservoir, which can take 13,000 tonnes of water.

The 10-acre site, now called Wydon Park, is being turned into a landscaped lake stocked with 10,000 coarse fish, 20 fishing and dipping platforms, and a kilometre of pathways. A public opening will be held in the summer.

“We have taken an overgrown, fairly ugly, brackish site and turned it into a place people can use and enjoy,” says Ian.

At Sele Well in Sele Park, an unsightly concrete and steel trash screen, which traps floating debris in the Cockshaw Burn, has been replaced.

Artist Matthew Fedden was commissioned to create a curved metal screen the shape of a ship’s bow. Instead of vertical concrete or steel columns to trap floating logs and trees, Matthew devised four oak totem poles with copper flashing to reflect the light.

The poles are mounted on steel piles driven eight metres into the burn bed.

Even as work was going on at the Wydon site, flood water was diverted last January, saving an estimated £2m in damage.

“We are delighted that the project has been completed and that it has already started to pay back its cost,” says Ian.

Stephen Marshall, contracts manager for contractors Volker Stevin, says: “It has been a large and complex undertaking.”

Agency project manager Nigel Darling says: “This scheme is a landmark in the history of the town.”