Thames Tideway

Cofferdam construction in the heart of London within a complex site, delivered and serviced via barge

Scope. Installation of steel tubes vibrated into the London Clay to a depth of 31m. All piling works were undertaken from a jack-up barge within the river, while all deliveries were also made via the river – with the exception of the concrete, where deliveries utilised low entry cab vehicles due to the proximity of the super cycle highway which ran adjacent to the site.

We undertook the marine piling works to facilitate the cofferdam works to allow critical path activities to commence – mainly the construction of the CSO drop shaft in the western cofferdam.

About the site. The site is located on Victoria Embankment next to Blackfriars underpass and adjacent to the super cycle highway. Blackfriars is one of Tideway’s largest sites, and one of a small number located in the heart of central London and on the river Thames.

Working from jack-up barges. All works were carried out from jack up barges on the river Thames. To prevent bored material from the piles entering the river, specially designed casing funnels were used to prevent spillage. To work on the river, all staff and piling operatives attended a 1-day riverside awareness training course. The piling works were executed within 24-weeks without any lost time injuries. In addition to the standard site inductions the piling staff and operatives also successfully completed an online ‘risk perception’ training course.

One section of the work site piling was near the Waterloo and City Underground tube line and these works were carried out during engineering hours throughout the night. Extensive measures were put in place to ensure minimal sound and noise pollution because of the proximity of residents to the south of the site.

Overcoming challenges. The location of the site was challenging – which we overcame through maximising river transportation, with minimal deliveries by road. With the exception of concrete, all deliveries were by barge from Tilbury or Northfleet Dock.

Although the project was complex from a logistical perspective, the entire piling works were managed by one project manager and site supervisor, working closely with the Principal Contractor daily to ensure best value was delivered for the client.

Expanded Geotechnical were also heavily involved in detailing the pile cage reinforcement.