ABSTRACT
The Brighton Group is an important geological unit of Melbourne because of its extensive surface coverage of the south eastern suburbs. The Group comprises two major formations, namely the Red Bluff Sands and the underlying Black Rock Sandstone. The Red Bluff Sands comprise clays, sandy clays, clayey and silty sands, sands and occasional silts. Apart from some sewers, few engineering structures reach the Black Rock Sandstone. The Melbourne and Metropolitan Board of Works have constructed several sewers in the Brighton group between Mordialloc and Caulfield using some open cut but mostly tunnelling techniques. The properties of the soils were determined by the Board of Works in investigations for the North Western Sewer between Brooklyn and the Maribyrnong River at Maidstone. During construction of the Mentone Interception sewer, frequent occurrence of organic material such as bark and leaves" was reported in clayey sands. The existence of such materials in the Red Bluff Sands appears to be rare, though rootlets are reported.
