Early groundworks monitoring for One Nine Elms, London

ITM Monitoring, now SOCOTEC Monitoring UK Ltd, was initially awarded a 10-week contract – which was extended until early 2018 – to provide monitoring of the early groundworks at One Nine Elms using existing instrumentation, which had been installed by a previous monitoring contractor, to analyse the impact of works on the surrounding congested area.

Summary of the works

Client: Multiplex
Start Date: Summer 2017
Completion Date: Early 2018

System

Inherited instrumentation, including:
Inclinometers
Levelling studs
Invar rods
Retro targets
3D prism targets
Data Presentation
Calyx Online Monitoring Software™


Nine Elms is the largest regeneration project in Europe, transforming 3km of London’s riverside into an ultra-desirable residential quarter, international business district and outstanding cultural and leisure destination. Soaring over 50 storeys, One Nine Elms will offer luxurious private apartments alongside a world-class five-star hotel.


The monitoring system features a mix of automated and manual instruments, including inclinometers installed in the diaphragm walls (D-wall) to monitor displacement of the walls during basement excavation works. Levelling studs in pavements and the capping beam around the perimeter of the site measure settlement and heave. In addition, a number of Invar rods – a nickel-iron alloy which is less susceptible to temperature changes – are installed in the crown of the Thames Water sewer running through the middle of the site, to monitor settlement and heave of the sewer. Several retro-reflective targets, mounted on two redundant buildings located at the boundary of the site and the adjacent New Covent Garden Market site, monitored movement of those structures prior to their demolition, and 3D prism targets are present on the D-wall capping beam to monitor the impact of the basement excavation works. ITM Monitoring’s Calyx OMS (Online Monitoring Software)™  is used to collect and display all of the automated data from the inclinometers, and the manual data is also uploaded to provide a complete picture of the impact of the early groundworks on the existing surrounding infrastructure.

'One Nine Elms is a congested site in the centre of Vauxhall and the groundworks being carried out onsite change on a daily basis, which can impact our site access. One day the monitoring team might have access to an area, and the next day it could be off limits within an exclusion zone. Ensuring that the routes used by our surveyors to carry out the daily manual monitoring remain accessible has involved close communication between ITM and the client, who mandated that – as one of the most important aspects of the works – monitoring surveyors should be granted the required access even if it involves temporarily pausing groundworks. Working closely with the client, we have built strong relationships with the people onsite to allow us to quickly access the required areas and ensure that works aren’t unnecessarily delayed.' Simon Hough, Project Manager at ITM Monitoring