Case studies

• Customer: Cotterell Thomas & Thomas
• Project: Haven Green Baptist Church, Ealing
• Date: 2009

The Challenge

When Cotterell Thomas & Thomas were instructed to undertake renovation work on the 125 year old Haven Green Baptist Church in Ealing, London W5, they were mindful of the fact that the available underground information of a church of this age would be not be good. With, foundations or voiding around the building, it was decided that undertaking a survey to update their understanding of the subsurface was a must.

The Project Manager, Tony Stevens, recalls that “the potential problem of siting scaffolding over unknown voids was a major safety issue that we had to manage before arriving on site. If any part of the scaffold was to collapse into a void or shallow hole in the ground, the results could prove fatal to either site personnel or any public in the area”.

The Solution

Cotterall Thomas & Thomas instructed Geotec Surveys to undertake a detailed survey looking for voids where the temporary structures were planned to be erected. The survey teamed deployed ground penetrating radar as the key technology in the survey as this would detect changes in the ground makeup and highlight anomalous areas where underground openings could lie. This technology meant that no excavations or disturbance to the church grounds were made, as the data is collected from above ground by sending radar pulses into the soil and measuring the returned reflections.

The Result

The survey proved useful in pre-planning the scaffold design, upgrading the church records and improving efficiencies of planning before the site work commenced. All of this aided improvements in the Safety Plan for all personnel on site as well as saving costs on exploratory excavations in a very sensitive environment.

Testimonial

Underground mapping is not a tool we had used very often before, but this one situation has shown the variety of benefits that can be achieved by making it a part of our pre-site planning schedule