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In the dock

Canal revival - A contaminated canal basin is being restored and brought back to life.Andrew Mylius reports from picturesque Stourport.

With ripples bouncing spring sunlight into your eyes, bright painted narrow boats tugging gently at their mooring ropes and ducklings foraging in the canal-side grass, it is easy to share environmental contractor Woodford Group's vision for a run-down quarter of Stourport, Worcestershire. The firm is in the process of recreating an 18th century canal basin which was inlled 50 to 60 years ago.

Woodford will reconnect it to the Staffordshire & Worcestershire Canal. And around it will be built 140 new houses.

Woodford's ructural consultant Alan Brookes notes that Stourport owes its very existence to the canal. In the 18th and 19th centuries, the town grew on the back of trade between ships plying the River Severn and barges on James Brindley's new canal network, which linked to Birmingham and the industrial Midlands.

'The canal was at the heart of Stourport.' That heart was largely lost during the 20th century as canal trade dried up. The town's four dock basins were lled in and turned over to manufacturing and timber treatment. Industry buoyed Stourport's economy for a short while, but in time it declined too.

The last 20 years - and the last 10 in particular - have seen a steady revival in use of the UK's canal network, however.

Commercial trafc has given way to leisure boating. Stourport is eager to capitalise on its canal town heritage, and Woodford has seized the opportunity to restore a part of it.

Restoring the 1.76ha canal basin is not simple. Timber treatment carried out on the site during the 1950s has left a legacy of creosote in the ground, and contamination from a defunct gasworks on an adjacent site, says senior environmental consultant John Davies.

Woodford started its £2M reclamation and remediation scheme by locating an original outfall culvert connecting basin and river and blocking it off, cutting the pollution pathway.

An intensive borehole site investigation identied creosote hot spots on site. These are being excavated and removed as hazardous waste to landll.

Clean material will be sent to ordinary landll. Davies says that the relatively small volume of contaminated material did not justify the expense of carrying out on or off-site remediation.

Excavation is being carried out with backhoe excavators down to the basin's original puddled clay base, 2.5m below ground level. This overlies river terrace beds of predominantly gravels. A self-annealing bentonite-geotextile sandwich will be placed once excavation is complete to ensure the basin remains watertight throughout its 120 year design life.

Unstable dock walls are being replaced with cast insitu L-shaped concrete walls. 'The L-shape means we don't have to excavate below dock oor level to create a foundation, so we're not going to create potential pathways for residual contamination into groundwater.

And it means we don't have to support the new wall using anchors. It's a simple, cheap, effective way of building a wall, ' says Davies. It will be capped with reclaimed sandstone coping to match the original.

Woodford is over half way through its project. Completion is due at the end of September.

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