With construction underway on Burbo Bank Extension, DONG Energy required the delivery and installation of two 200-tonne transformers at the onshore substation, which was done by Collett, a UK company specializing in Heavy Haulage, Heavy Lift, Marine Agency and Transport Consulting.
SDV UK Ltd called the company to facilitate the ship’s discharge at the Port of Mostyn and the transport to site of the two large cargoes. With the ship arriving in July, the Collett team was onsite to undertake the project with two ballast tractors and a 14 axle modular hydraulic flat top trailer.
Having already undertaken the required planning for discharging the vessel, the Collett Heavy Lift Team began the task of unloading the components from the hull of the ship utilising a 1,200-tonne crane.
Each load was lifted from the ship and delivered to the awaiting 14 axle trailer. The loads were then transported to an agreed holding position at the port where they were stored on stools until a suitable construction stage at the substation allowed for delivery.
The delivery of the two loads took place in September, but due to the size and weight of the transformers, therefore a more specialist method of delivery had to be devised to facilitate the loads owing to height and structure restrictions en route.
In order to utilize the load exit at the Port of Mostyn, the loads were required to travel over a level crossing. Due to the weight of the loads and the size of the rail track, Collett were required to obtain official track possession. This allowed the two transformers to travel over the level crossing on modular trailers.
The loads would then be positioned in a local layby, approximately one mile from the Port, for transhipment from the 12 axle flat top to the 550-tonne capacity Girder Bridge for onward transportation. The loads once again had to be positioned on stools whilst the Collett Team took to building the modular Girder Bridge around the load.
Once constructed, the overall dimensions of the combination and load required specialist route planning from the Collett Consulting Team, providing Traffic Management Plans and route analysis ahead of the project to ensure a safe delivery. This required the team to pore over mapping data for several days, planning the route to prove suitability, undertaking Swept Path Analysis and conventional surveying techniques to plan the project.
The final route plan highlighted a weak bridge, too fragile to accommodate the Girder Bridge and load, consequently the team obtained a temporary traffic restriction order, which required a 12-week approval process. This allowed Collett to contraflow the A55 dual carriageway in the wrong direction, therefore avoiding the bridge and allowing the combination to re-enter the A55 in the correct direction.
Travelling under police escort, Collett’s 10-man team departed from the Mostyn layby on a late evening in September.
Once on site, the team unloaded the transformer and maneuvered it into position onto a plinth and aligned onto anti vibration pads. Five days later and following the exact same procedure, the second transformer was collected from the layby and delivered to the site.