Client: Network Rail
Contractor: Dyer and Butler
Duration: 2 months
Date posted: 11-11-2013
MMC Diving Services were contracted to design and fabricate a deflecting barrier from steel to divert up to 2500 tonnes of water away from the bridge abutment. A custom designed containment curtain was then to be hung around the working area to encapsulate the works.
Due to the sensitivity of this beautiful site, being SSSI & RAMSAR, all plant and equipment were sanitised; only plant with panolin bio-oil / grease were used within 10m of the river.
Once this was achieved, existing rock rolls were removed from the riverbed so excavation could begin in preparation for the Enviroform bag work. This was placed in position and grout pumped across the river in a double lined casing.
Scour, caused by swiftly moving water, can scoop out scour holes, compromising the integrity of a structure. Bridge scour is one of the three main causes of bridge failure (the others being collision and overloading).
It has been estimated that 60% of all bridge failures result from scour and other hydraulic-related causes. Water normally flows faster around piers and abutments making them susceptible to local scour.
At bridge openings, contraction scour can occur when water accelerates as it flows through an opening that is narrower than the channel upstream from the bridge.
Degradation scour occurs both upstream and downstream from a bridge over large areas. Over long periods of time, this can also result in lowering of the stream bed.
"This project certainly isn't the largest we have ever undertaken, but I can assure you it has become the most important project we have on at the moment and the most sensitive. Your team have done everything by the book. I would personally like to thank you for your persistence and professionalism throughout this entire project."
"I have to say Sam, the organization and operation that you run is exemplary: from the supervisors right down to the operatives. I would gladly recommend MMC to other major construction companies and I look forward to working with MMC in the future."
Site Manager & HSEQ
Dyer and Butler