This crucial weir, which maintains levels to allow navigation to the Huddersfield Broad Canal, upstream to the Rochdale via the Calder & Hebble and downstream along the Calder & Hebble, is midway through a £2m million winter overhaul to install a new 40 metre weir and a new fish pass.
In the past two years this section of waterway has been forced to close on two occasions as emergency temporary repairs were undertaken by Canal & River Trust staff to repair failed sections of the weir which led to the navigations being closed.
Weir critical to trans-Pennine routes
The weir is critical to two of the trans-Pennine routes which use the Huddersfield Narrow Canal and Rochdale Canal which are enjoyed by thousands of boats each year. The Calder and Hebble and Huddersfield Broad navigations have not had to be closed during the works and the new weir is expected to last around 120 years.
Linda Milton, the Canal & River Trust's project manager for the Cooper Bridge weir scheme said: “This is the largest project happening anywhere on the waterway system during this maintenance period and is really important for these navigations. The weir is a completely new structure with a heavily reinforced base around four metres below the crest level. The remaining structure is constructed with fibre mesh concrete with steel sheet piles up and downstream tying into a sloping concrete apron to the upstream and a stepped concrete apron to the downstream. The weir also includes a bywash facility for fish migrating downstream. The main fish pass is a Larinier type and also incorporates an elver pass.
“The river cannot be closed fully and so extensive temporary works in the way of steel sheet piles have had to be driven into the river bed to form two cofferdams so the works can be carried out in two halves across the river; some of the piles are 13m in length. This enables the works to be constructed in the dry and at the same time maintain the river flow. However, due to all the heavy rainfall in 2012 this has proven a real challenge and several major floods to the river have caused delays as levels have been so high they have flooded the cofferdams out.
“The aim has been to install a new durable, robust, low maintenance structure that safeguards the navigations. Because of the nature of this river system, there is a high probability that these failures would have kept occurring so it's important we've taken this action to avoid any further disruption to the three navigable waterways which rely on this weir.”
Ian Ward, site agent for May Gurney who are carrying out the reconstruction, comments: “The recent spells of bad weather have caused quite a few incidents of flooding to the site which demonstrates the challenges we face when tackling these types of constructions job in this environment. However, the team have been working really hard and are making steady progress and we hope, weather permitting, to have the works complete by the end of April.”
The works are split into three phases and currently work is underway on phase two. This involves the construction of the main weir structure, a bywash facility to the left bank and a high retaining wall to the left bank. The main weir has a reinforced concrete base and on top of this there are six further lifts of concrete to form the weir. The retaining wall and bywash are now complete and the third lift to the weir is currently being formed and the structure is programmed to be complete by the end of January.