Magnox Sizewell

Case Study Overview

Red7Marine (R7M) installed 2 x 350mm HDPE pipes through an existing outfall culvert at Sizewell A power station as part of the stations decommissioning works.

At a glance

  • Location: Sizewell A Power Station, Suffolk
  • Plant used: Haven Seajack
  • What we did: Red7Marine installed two 350mm replacement pipelines as part of the decommissioning work at the station

The Challenge

Red7Marine was approached to provide an innovative solution in the fitting of two new pipelines to run along an existing outfall culvert. The existing outfall ran from a submerged outlet offshore, to a limited access inshore pit eighteen metres deep with approximately ten metres of water in at all times.

Several items of bespoke plant were required including the fabrication of ROV access frames and pipe storage mounts which were used on the Haven Seajack to pull the pipes through the existing outfall. Specialist pipe weights were also designed and fabricated in house by the R7M engineering department.

The project presented further challenges with its location being on the secluded east coast of England.

Sizewell Challenge

The Solution

The R7M team worked both inside and outside of the nuclear facility, making close liaison and the
on-going communication with the client imperative. It was also paramount that very high standards of safety and environmental awareness were always maintained. R7M incorporated its safe systems of work into the client’s systems using a collaborative approach.

This project encompassed the hire of various items from R7M’s extensive marine fleet including our Jack Up Barge ‘Haven Seajack 1’ and a custom fabrication of a submergible steel shute – specifically designed to fit within the existing outfall pipe to assist with the pipe pull in.

R7M’s labour, supervisors and plant was critical in the installation of the two new 350mm pipes. Through careful marine planning and innovative solutions, the operations were completed successfully.

R7M also supplied various smaller items of marine plant, skilled operatives and use of its vast diving services in various roles to allow for an efficient installation of the new pipelines.

A specialist ROV subcontractor was utilised and managed by R7M. The contractor was appointed early in the supply chain ensuring its agreement with the method and buy in to the proposed works. This partnering agreement bore dividends with a successful project carried out by both parties.

All operations occurred within the close vicinity of the Magnox Power Station and therefore specialist care and safety codes were followed by R7M to accommodate for these restrictions.

Sizewell Solution

Sizewell Solution

Complete Package Delivery

Red7Marine provided equipment, crew and engineering support to the project to ensure our clients’ successful delivery.

Solutions Provider

Red7Marine provided specialist barge and marine experience to the project.

Skilled Team

Red7Marine’s operations and engineering teams are all highly skilled and experienced in the marine environment providing partners with an industry-leading service.




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“I wanted to share the excellent feedback on the piling works for Barrier Gardens Pier. A success all round project in terms of task at hand, depth, timing, budget, comms and health and safety.  We’d be happy to work with the Red7Marine team again and I shall be in touch as soon as something comes up. Please pass on our thanks to the team for making the project a success.”

Richard Hopperton, Head of Procurement Port of London Authority