CLIENT: RWE Innogy
TYPE: Offshore wind farm
LOCATION: Liverpool Bay
WATER DEPTH: 13.4m – 21.4m
DATES: 2011 to 2015
LOC Scope of Work
Marine warranty surveying is usually a requirement of the developer’s ‘Construction All Risk’ insurance and experience has shown that it can significantly reduce the number of claims, which in turn reduces the insurance costs. LOC was appointed as marine warranty surveyor to review the operational procedures and to inspect the principal offshore construction vessels to confirm their suitability for use on this project.
LOC has worked closely with the developer, the insurance underwriters and brokers to identify the key reviews and surveys for this project. These include attending on site for the first performance of each key operation to provide the necessary assurance to developer and insurer. If it is performed well then the surveyor need not attend each time the operation is repeated, thus saving considerable costs.
LOC’s work includes the review of procedures and making recommendations on their implementation, attendance on site and the issue of Certificates of Approval before each first key operation of monopole foundation, tower, nacelle and blade installation, transformer platform, scour protection and directional drilling operations for the export cables. We were in attendance for the whole export cable transportation and installation phase, and the witnessed the first ten array cable installations. LOC also carried out surveys of the principal offshore jack-ups, barges and their support craft and reported on their suitability.
Brief Project Details
The site developers are RWE Innogy. The development involved the installation of a 576 MW wind farm comprised of 160 wind turbines and 2 offshore substations located in Liverpool bay 13km from Prestatyn, North Wales. Soil conditions high tidal flows, scour and several cable and pipeline crossings all provided additional construction challenges which had to be properly engineered and carefully implemented. It involved the laying of approximately 140 miles of cable and included 4 beach pull-ins, all the cables were buried.
A wide selection of vessels was used on this site including jack-up construction vessels, heavy lift vessels, DP vessels and barge for cable laying and ploughing. Specialised rock dumping vessels for scour protection were also used as well as cargo vessels/barges for the trans-shipment of cables from the Netherlands and Norway.
Birkenhead, Liverpool and Burntisland were used as mobilisation and transhipment ports.