How much needs to be excavated?

This depends on the type of soils that you are dealing with. If you are excavating for foundations then you will need to remove all topsoil and organic material along with any localised softer areas before you commence construction of your foundations. Testing can be undertaken to confirm the actual likely depths that will need to be removed. Construction of roadways and building platforms often requires large volumes of excavation to be undertaken. Normally during the design processes an attempt will be made to balance cut and fill volumes so that no material needs to be removed from the site or, alternatively, imported from quarries.