During any proposed development the most difficult portion of the works to change or alter is the ground conditions prior to the development.

The impact of soft sediments, water tables, reactive clays or hard rock can have huge cost implications and result in costly delays during excavation and construction if they are unknown or not planned for. Geotechnical site investigations conducted prior to final design and construction provide detailed data on the actual site conditions to allow optimal design and construction of structures within the client’s budget.


A medium scale excavator can easily drill pier footings to 5 – 6m depth through the clay soils and weathered shale that exist throughout most of the western half of Sydney, in search of refusal on ‘hard’ bedrock. However what if the structural engineers footing design only requires extremely low strength bedrock, which appears like a clay and is sometimes located at <3m depth?. That could result in half the volume of required concrete and steel for the footings. For a standard residential structure requiring 100 pier footings that can result in a potential saving of $15 000 in concrete alone, plus add steel and installation costs (July 2014).

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