David Lees and Associates was appointed by Austress Freyssinet to develop a soil mixing/jet grouting technique and to carry out trials at Sydney Airport..

The Parallel Runway at Sydney Airport is a reinforced earth structure in Botany Bay. The precast panels around the structure have geotextile covering the joints to prvent washout of the sand behind. In some places this material has failed causing significant sttlement behind the panels and exposing the steel reinforcement strips. A method was proposed to replace this material in-situ with a series of interlocking grout columns.
David Lees and Associates assisted in the development of the equipment and carried out site trials to develop and prove the system.