The project, for the Energy Alliance, involved the emergency demolition and replacement of a dilapidated tower, complicated by the fact the structure was located on the estuary of the Afon Dwyryd, near the Penrhyndeudraeth toll bridge in Gwynedd.
“The specific challenge of this project was simply the location” says Groundforce Bridge Manager, Terry Mead. “This is an estuary, very close to the coastline and so tide times have taken dominance in the scheduling of working hours.”
The requirements from the client included a bridge width of 6m, to accommodate a 200 tonne piling rig, which was used during the remedial works. A critical factor of the scheme was the scheduling. With immediate emergency works taking place once the tower was condemned as no longer fit for purpose, a high speed mobilisation from Groundforce Bridge was paramount. Within one working week, the scheme developed from an initial enquiry to a complete installation of the 6m x 10m Vehicle Bridge.
This task was achieved with the joint efforts of Groundforce Bridge operational staff, technical staff and the assistance of operational staff at Groundforce’s Hilton depot in Derbyshire who carried out modifications to the handrails.
A combination of soft alluvial soil and constant tidal fluctuations presented a significant challenge for the construction team.
Groundforce Bridge met this challenge by providing a site presence for full days at a time, working up to 15 hours per day with the client’s maritime trained team, enabling them to continue installing the bridge amongst the flooded terrain during high tide times.
Groundforce Bridge also liaised with the client’s temporary works engineers, providing product information to incorporate into their design, which was amended after first-install.
This design modification required Groundforce Bridge to send a second operational crew to site to undertake remedial works, which included a full recovery and install over a period of 15 hours during low tide. During the same operation, the crew installed a 7m Vehicle Bridge at a second location further down the power line, in order for the client to continue their works unhindered during this critical time of their schedule.
Martin Woodford, project change engineer for Babcock said “Groundforce were chosen primarily due to the availability of two large temporary bridges and the company’s willingness to modify the bridges to suit our needs at very short notice, demonstrating acute customer awareness and ability to react to pro-actively to challenging customer demands.”
“The paramount installation times, working near water during high tide and the extensive referencing of information with the temporary works engineers for Energy Alliance made this project one of the more complex schemes of 2013” commented Terry Mead.
Work started in October 2013 and the 10m x 6m Vehicle Bridge is still currently on site.