£700,000 project to restore underwater tunnel

10:24pm Friday 4th July 2008

Comments (1)   Have your say »

A 200-YEAR-old underwater tunnel has received £700,000 worth of work as part of an ambitious plan to restore it to its former glory.

Denham Culvert near Denham was built to divert the river Frays beneath the Grand Union Canal when it was constructed in the 18th century.

This allows the river to flow beneath the canal, which runs through a raised embankement that crosses the Frays.

The recent repairs were carried out by British Waterways.

Simon Bamford, general manager for British Waterways London, said: "The original canal engineers followed the instructions of their funders - usually powerful local landowners. A number of mills operated in the Denham area at the time of the construction of the Grand Union Canal towards the end of the 18th century.

"The mill owners insisted that local rivers which powered their mills be unaffected by the new canal and so rivers like the Frays were diverted beneath the canal using a series of tunnels.

"It's essential that these historic structures are maintained as part of our work to keep water in the canal. Fracturing of these old tunnels can lead to flooding. We regularly inspect all our structures and draw up a repair and maintenance programme which is focused on the winter months to minimise disruption to canal users.

The project took 18 months of planning and six months of construction time, plus an unexpected delay when a moor hen decided to nest on the site. Work was suspended until her eggs were hatched.