Management of reactive and carbonaceous materials in the earthworks design for the Hunter Expressway, Minmi to Buchanan section

One of the greatest project challenges and risks for the eastern (Minmi to Buchanan) section of the Hunter Expressway was the management and design for the proportionally large amounts of poor quality materials derived from the Newcastle Coal Measures formation. The near balanced earthworks design, coupled with the very strict clearing restrictions and challenging terrain, compelled designers to incorporate expansive and carbonaceous materials, which would otherwise be spoiled because of their poor engineering properties, into the road formation. This paper presents the geological setting, characterisation of the earth materials, development of the encapsulation design approach used and implementation to date. In conclusion opportunities for further design development are discussed.