Working to reduce risk of flooding for residents of historic town

Working on behalf of the Environment Agency, Team Van Oord is successfully delivering emergency flood prevention works to protect the historic town of Sandwich in Kent.

Sandwich lies close to the coast on the River Stour, and a short section of approximately 35 metres of the river wall at Pillory Gate Wharf was identified as being on the verge of ‘catastrophic collapse’ – and therefore deemed to be posing a safety risk to the public.

The Environment Agency instructed Team Van Oord to carry out emergency works to construct and install a new anchored sheet pile wall, with capping beam and new brick wall to match the existing vernacular.

The pile installation was programmed for three weeks, but the 41 sheet piles were actually successfully installed in just one week – using a 38T excavator with Movax and hammer attachments, operating from a jack-up barge.

A jack-up barge is a mobile platform used when working in a water environment. The legs are lowered to the riverbed to secure the barge in position, and then raised to allow it to be moved when required.

The jack-up barge and excavator were deployed to complete the following works:

  • To install concrete plugs and partially backfill between the sheet piles and existing wall;
  • Welding and installation of waling to the back of the sheet pile wall;
  • Coring and stitch drilling to enable the ground anchor installation. The extent of this final element of the works was greater than anticipated due to the thickness of the existing river wall.

Joe Granger from Team Van Oord said: “The pre-mobilisation probing and proofing of the pile line that we carried out in advance proved valuable and, combined with an obstruction-free path and favourable ground conditions, greatly assisted with the speedy installation of the piles.

“We monitored vibration levels throughout the piling works to allay concerns expressed by some local residents, and this will continue until we have completed the ground anchor installation.

“Throughout the works we will also continue to provide letter drops to local residents to update them on progress and timescales.”

The earlier than expected completion of the piling element of the project allowed the Team Van Oord project team to carry some other works prior to sub-contractor Keller UK arriving on site to install the ground anchors.

These works included installation of a temporary floodwall using polythene enwrapped jumbo sand bags, and demolition of the existing brick wall to ground level.

Keller UK was then mobilised over the weekend of 28-29 March, to enable the ground anchor installation to commence as planned on 30 March, to coincide with the neap tide.

While on site, the project team was also asked to carry out emergency works to replace the roof of a local pumping station damaged by Storm Dennis in February 2020.

The project is scheduled for completion by the end of July.

23 April 2020

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