Project: William Girling Reservoir
Scope: Install Secondary Isolation
Location: William Girling reservoir, Chingford
In March 2017 we were commissioned by Barhale/Thames Water to locate, measure and provide isolation plates for their four inlet pipes located at circa 16 metres water depth.
We adapted one of 20’ safety vessels to house our low frequency sonar to work effectively at medium range speeds and with the sonar scale set to 40 metres we found the twin pipelines within a couple of hours, we then narrowed the range to 10 metres and focused on a detailed asset survey.
The high level of detail from the sonar imaging allowed us to estimate the silt level around each inlet, along with any potential hazards likely to be encountered during the subsequent diving operation.
We marked each inlet with a longitude / latitude coordinate allowing repeatable visits to each location without the use of marker buoys.
Contouring the reservoir depth gave us vital information for implementing a safe dive-plan for the installation of the secondary isolation seals.
Once on location, our dive team set about cleaning mussel growth from around the inlets and then carried out an accurate survey of each one to determine the precise dimensions for the fabrication of the secondary isolation seals.
The Isolation seals were designed and fabricated in house to a very fine tolerance and were manoeuvred into position on site utilising an ‘A’ frame and lifting winch was set up on the dive support pontoon.
Testimonial: WSG has provided an excellent service on my projects, from ROV surveys to installing secondary isolation plates in reservoirs. WSG/Tunnel Vision are very professional and a pleasure to work with.
Andy Simpson– Client