A forgotten water course and a failing dam

In recent months, visitors to Burrs have been faced by the unfamiliar spectacle of a new waterfall cascading off the northern buttress of the pipe bridge, and the area around the Lamppost Café being under enough water to result in wet feet and temporary closure of the café on two occasions.  Many major floods have occurred at Burrs over the last few decades, but nothing like this has arisen before.

It is now 30 years since the landscape around Calrows Mill was restored, at a cost somewhere well in excess of £200,000 of public money.  The centrepiece of this work was the massive masonry wheelpit which had contained a 100hp waterwheel, and the plan was to introduce a crashing cascade of water into the wheelpit, to demonstrate graphically how water power could drive a large textile mill.

New ‘pipe bridge’ over Irwell under construction in 1992, Stock Street visible in distance.

To this end, civil engineers Parkes-Winstanley and contractors Groundwork Landscapes were engaged by Bury MBC to carefully reinstate the industrial water system, which was last used in about 1920.  In 1992 a new footbridge was erected across the river by Morripon Bridges & Structures, containing a pair of large water pipes, to replace the original timber and masonry aquaduct.  The headrace through to the Calrows Mill site was carefully cleaned out and regraded, as was the adjacent millpond, requiring the use of a heavy RB32 dragline.

Newly-dredged fishing pond on left, newly-graded headrace on right, extending towards ‘Brown Cow’.

The wheelpit was re-excavated and consolidated, and the tailrace back to the river was in part replaced by a concrete pipe, to repair damage caused in 1984 by the construction of a manhole down to the North-South Sewer Interceptor Tunnel.  Finally, hundreds of tonnes of silt was removed from the open tailrace which runs parallel to the river.

Damaged tailrace tunnel near wheelpit, centre left is concrete manhole down to interceptor sewer, top left Stock Street is visible.

And the whole of this water system was carefully calculated and carefully balanced, so that if regularly maintained, water would continue to flow through the system, washing out any silt and organic matter, and ensuring that any flow would be contained within the system.

Almost three decades has elapsed since this restoration was completed, and I don’t believe that any maintenance or cleaning of the Higher Woodhill water system has occurred, and a sorry state of affairs has emerged.  The headrace is so badly silted and overgrown (even containing mature trees) that the flow has been reduced to no more than a sluggish trickle.

Graded headrace channel just right of centre, Stock Street visible upper left.

 

In addition to the sluice being damaged at the big weir, this was part of the cause of the recent waterfall at the pipe bridge, because most of the water reaching that point had nowhere else to go.  By the café, the flooding scoured out the bedding beneath the flags, requiring expensive repairs.   

And when water does reach the Higher Woodhill mill site, instead of cascading into the wheelpit, perhaps 50% of it spews through gaps in the northern wheelpit wall, indicating a deeply-buried engineering issue.  And you don’t have to look far to identify the origin of this water problem.

Wheelpit with water gushing through fissures in right-hand (northern) wall.

On the adjacent dam, a paved area surrounds an interpretation board.  Here, just behind the dam wall, is a deep open fissure, which is undermining the paved area.  It appears that the clay core of the dam is washing out, and the water forcing its way through underground channels, and then through the wheelpit wall.

Paved area between millpond and wheelpit. Arrow indicates location of fissures where dam has been voided by water pressure. Stock Street visible upper right.

It is only a matter of time before the dam slumps and all of the water is lost, and no amount of prevarication and long-winded consultation will cure that particular problem.  Professional engineering advice and works are well overdue, and if that doesn’t happen, then a substantial part of the Burrs water system may be irretrievably lost.           

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