Noise and Vibration Mitigation

CSJV and Kilnbridge worked collaboratively to explore options for South D Wall reduction. This activity involved removing 1650 tonnes of reinforced concrete from the 268m wall which is up to 1.5m thick.

Various methods were put forward including:

• Drilling and bursting
• Mechanical breaking (excavator)
• Plunge (and normal) wire sawing

Plunge wire sawing was chosen as the preferred methodology as it is the least disruptive to local, sensitive receptors including high profile commercial and hospitality firms.

Holes are cored into the concrete, into which wires are inserted that cut through the concrete under tension into blocks. This is the largest plunge wire sawing project undertaken in Europe and potentially the world.

This method avoids the need for excavators and breaking. It therefore has significantly lessened noise impacts than the other proposals (considerably less than mechanical breaking ~130db). This approach also creates minimal vibration.

The blocks are then lifted by crane and transported off site to be crushed further avoiding noise impacts in a highly sensitive area.

This was presented to local authorities and was commended by Westminster City Council as excellent best practice in the construction industry and a true demonstration of working to Best Practicable Means.