The Valley Lake Project involved the rehabilitation of a former basalt quarry for residential development. Prior to rehabilitation, the quarry was partially filled with stockpiles of waste rock and overburden materials and a lake had formed in the quarry base. Rehabilitation involved the removal and processing of approximately 2.4 million cubic metres of stockpiled fill for placement as engineered fill, the creation of a feature lake and stabilisation of existing quarry walls.
The project encompassed many geotechnical challenges including the development of a strategy to engineer deep fill platforms using Quaternary age Newer Volcanics material varying from high plasticity basaltic clays to weathered basalt rock with boulders up to 3 m in size. Critical to the residential housing development was the settlement behaviour of the engineered fill, particularly with regard to the performance of shallow footings founded on a fill thickness of up to about 35 m.
This paper presents the results of monitoring of settlement plates installed within the fill profile. The results of the settlement monitoring show the behaviour of the various fill materials during construction, post-construction and during the recovery of groundwater levels within the fill.