Oakleigh Depot – Embankment Monitoring, UK

Project summary

The Oakleigh Road Depot, located in Barnet, North London, is a logistics facility for local waste disposal and council maintenance vehicles.

The entrance to the depot and fuel refill station showed signs of significant underlying ground movement and subsidence, with apparent surface cracking and bulging within the adjacent retaining wall.

The brief

Due to the critical movement, Murphy Geospatial mobilised a team within twenty-four hours of notification to the site to install a comprehensive autonomous and manual monitoring system, measuring horizontal and vertical movement along the top of the nearby retaining wall and all surfaces within the vicinity. The system also included relative inclination and structural deflection of the retaining wall and nearby buildings.

The system was set up to allow for around the clock data visualisations, and real-time alarming in case the rate of movement breached the critical limits. The manual monitoring network was set up as a secondary system for redundancy purposes and confirmation of movement.

The challenges:

Our task was to create a stable control network in an area influenced by substantial ground movement and commission the system quickly. This was achieved by installing multiple reference prisms beyond the area of movement with additional large baselines beyond the depot that the manual network could coordinate and orientate from. Before mobilising to the site, photos of the affected area and the depot, in general, were issued so some decisions could be made prior to attendance.

Our work:

Murphy Geospatial commissioned the following automated system to ensure the ground movement was monitored accordingly where mitigation actions could be taken if required, which reported in near real-time, measuring highly accurate, absolute, and relative movement.

2 no. Total Stations
15 no. Bi-axial Wireless Tilt Sensors
+30 no. Geodetic survey prisms
1no. GNSS Monitoring Station
2no. Wireless Optical Displacement Sensors

All data was collated and viewed through an online web portal via graphical and tabulated displays where trends could be analysed.

In addition, the Murphy Geospatial team attended the site to carry-out 3D manual monitoring checks and measure pre-installed inclinometers to determine below the surface ground movement. The solution provided geospatial certainty to our client, allowing the stabilisation works to be carried out with the assurance and confidence that the embankment and surrounding ground was no longer at risk of further subsidence.

Our team:

Our highly-skilled engineering team installed an automated and manual monitoring system, along with our surveyors implementing the control and network coordination. This gave us the detailed information required for the project, ensuring that we gave vital support to the council during the stabilisation works.

We are renowned for our knowledge and experience in providing a comprehensive range of monitoring services to clients and delivering verified geospatial data recorded over time.

Results

The observation data was viewed via an online portal and summarised in a weekly report. If a trigger was breached or a critical event occurred, the site team and the council were ready to take the necessary action before it was too late.

The success of this project underlines our reputation in delivering services to equip our clients with the data and information they need to make decisions at every stage. We draw on the experience and skills of our people to deliver certainty our clients can trust.