ABSTRACT
The Werribee Formation is the lowest unit in the sequence of Tertiary sediments and lavas that were deposited in the Port Phillip Basin. The Werribee Formation consists of terrestrial estuarine, fluvial and some paludal sediments. The Werribee Formation is rarely found in outcrop within the Melbourne area. The main knowledge of the Werribee Formation has come from ground investigations for engineering projects. The clean sands and gravels of the lower Werribee Formation are highly permeable groundwater aquifers. Groundwater from the Werribee Formation pumped from a borehole is used to augment supply and improve the quality of water in Cherry Lake, Altona. Because the Werribee Formation sediments in many cases consist of low cohesive to uncohesive mixtures of silt, sand and gravel, soil moisture is a critical factor in excavation stability. West of Melbourne, the Werribee Formation contains a confined aquifer with a high pressure head which has led to flooding problems associated with two large excavation projects.
