In August 2019, OnSite received an emergency call from Kier (on behalf of the Canal & River Trust) asking for us to attend Toddbrook Reservoir and join the team looking to protect the residents of Whaley Bridge, Furness Vale and New Mills from a potentially catastrophic dam failure. We immediately dispatched specialist teams and equipment from across our national operations, to support the multi-agency engineering design team.

The heavy rainfall experienced in the preceding days had partially dislodged the large concrete slabs on the overflow spillway undermining the underlying structure of the Whaley Bridge dam. The approach adopted to secure the structural integrity of the dam was to fill the void/shore up the dam with aggregate and grout it in place. OnSite quickly mobilised over 400 tonnes of grouting materials, which arrived at Whaley Bridge by Friday afternoon, ready to support the spectacular airdrop of hundreds of one-tonne bags of ballast onto the dam by an RAF Chinook helicopter.

Over the next 48 hours, the RAF airdropped 525 tonnes of aggregate onto the spillway to help secure it. In between drops, OnSite secured the bags of aggregate into place using grout and foam-concrete to ensure maximum contact between the added weight and the face of the dam. Our teams worked tirelessly, day and night, over that weekend to get the job done in a challenging, dangerous environment. Teams remained on standby until residents were able to return to their homes on 7^th August.

The local community are to be commended for their composure during such an emergency and we thank them for the hospitality they showed to our crews.

Download Case Study