CIDH: Cast in Drilled Hole Piles are used to support or reinforced structures built on ground subject to movement. They are simply reinforced concrete piles cast in holes drilled thru unstable ground layer to predetermined elevations. A borehole is drilled into the ground, then concrete (and often some sort of reinforcing) is placed into the borehole to form the pile. Rotary boring techniques allow larger diameter piles than any other piling method and permit pile construction through particularly dense or hard strata. Construction methods depend on the geology of the site; in particular, whether boring is to be undertaken in 'dry' ground conditions or through water-saturated strata.