Shoreham Adur Tidal Walls: a flood defence scheme with ArcelorMittal sheet piles

Shoreham-by-Sea is an historic seaside town situated on the River Adur estuary in West Sussex. In recent years, it had become vulnerable to flooding with existing defences breached in 2013 after heavy rainfall and a tidal surge. The Environment Agency carried out extensive research to calculate potential flood risk in the River Adur estuary, resulting in the Shoreham Adur Tidal Walls scheme.

Detailed information

Protecting residential and business properties, preserving flora and fauna

The 45 million GBP Shoreham Adur Tidal Walls (SATW) flood defence scheme was funded by the Environment Agency, with additional funding from the Coast to Capital Local Enterprise Partnership, Adur District Council, and West Sussex County Council. The scheme comprises 7.2 km of new defences along the River Adur: 1.8 km on the east bank between Coronation Green and the A27 road bridge and 5.4 km on the west bank between the river mouth and the A27 road bridge.

The challenge was to develop a new flood defence scheme to protect residential and business properties on either side of the estuary for the next fifty years with minimum impact on the lives of the residents, whilst preserving the flora and fauna of the area which includes significant expanses of saltmarsh and mudflat.

7 out of the 10 sections use steel sheet piles

The design, by Mott MacDonald, divided the works into ten different sections or tidal 'Reaches' with each one representing a different challenge and requiring a different solution. Seven out of the ten Reaches used steel sheet piling. Other solutions included embankments, rock revetments, flood glass, and property level protection.

The work was carried out by Mackley, as part of Team Van Oord, a joint venture partnership. ArcelorMittal Sheet Piling collaborated with Mott MacDonald and Mackley on design and installation issues and for all Reaches for which steel sheet piles were used.

Sheet pile construction started in September 2016 and was completed in March 2018. ArcelorMittal worked closely with Mackley on the logistics, supplying over 5000 tonnes of steel sheet piling. The ArcelorMittal steel sheet piles were produced in Luxembourg where liquid steel is made from 100% scrap before being rolled on its steel mills and transported by train and then ship directly to its facility located in Shoreham port.

Sheet pile installation with reduced noise and disruption

Engagement with the local community was a key aspect of the construction, and at Reach W5 – Riverbank Mackley were able to obtain a design change to allow them to use a pressing installation technique along with PU28 U-Piles from ArcelorMittal.

A Giken piling machine (the so called "silent" press) was chosen as it is able to work in confined spaces, installing piles hydraulically which creates less noise and disruption. 1176 piles at 11 m long were installed in close proximity to house boats along the river. At Reach E1 - Tollhouse Bridge, Mackley installed 500 tonnes of ArcelorMittal’s proprietary HZ®/AZ® system from a jack-up barge.

Other parts of the scheme used the AZ 26-700 and AZ 28-700 Z-sheet piles developed by ArcelorMittal for their weight efficiency. The completed scheme significantly reduces flood risk to more than 2300 properties, including 169 commercial properties in Shoreham and East Lancing, as well as the road network, railway line, and Shoreham Airport for the next 100 years.

Project information

  • Shoreham-by-Sea
  • United Kingdom
  • 2018
  • Client:
    UK Environment Agency
  • Designer:
    Mott MacDonald
  • Contractor:
    Mackley, part of Team Van Oord
  • Photos:
    Courtesy of Mackley, part of Team Van Oord
  • Text:
    ArcelorMittal Sheet Piling