Coastal-defence works

Description

IoACC are working in partnership with Stena Line Port Ltd to develop a refurbishment scheme for Holyhead Breakwater which is 1,5 miles long and is a historic Grade II* listed structure. Royal Haskoning DHV have developed a solution however the design is still subject to refinement. The project is likely to be delivered in phases and potentially separate contracts. IoACC are working in partnership with Stena Line Port Ltd to develop a financially viable refurbishment scheme for Holyhead Breakwater. The aim of the project is to reduce erosion of the existing rubble mound, thus securing the structure for future generations. The Holyhead breakwater structure is 1,5 miles (2,4 km) long, is considered the longest breakwater in Europe and is protected by CADW as a historic Grade II* listed structure. A Grade II listed lighthouse is also located at the head of the breakwater. Royal Haskoning DHV have developed a solution however the design is still subject to refinement, particularly at the roundhead. The project is likely to be delivered in phases and potentially separate contracts and IoACC and Stena are currently looking to gain all the necessary consents and funding. We would like to invite expressions of interests for this scheme construction. It is likely to cost in the region of 60 000 000 GBP and could be programmed to straddle financial years or in phases. Works – the solution comprises: Seaward side The existing rubble mound foundation will be protected by 2 layers of concrete tetrapod armour units which are supported by a 2 concrete chevron units at the toe. The width of the tetrapod/chevron berm will be 30 m. A standard tetrapod armour unit size of 45 t has been selected, which is equivalent to a 18,1 m3 unit and the chevrons units are 60 t. In places the existing rock mound foundation will need to be widened by using rock. Leeward side It is envisaged that the rubble mound on the lee side will be reinforced with an articulated concrete block mattress (ACBM) 150 mm thick. Indicative timescales Design and consents summer 2020 Funding applications 2020/21 Tendering 2020 Construction 2021-2026