Stabilisation of biosolids with admixtures for potential use as an embankment fill material

Biosolids are an end product of the wastewater treatment process and contain many of the constituents removed from the influent wastewater. This paper is based on a project currently implemented in Victoria to assess the viability of using biosolids as engineered fill material for road embankments. A series of geotechnical lab tests were conducted to evaluate the engineering properties of biosolids samples retrieved from Western Treatment Plant (WTP) in Victoria, Australia. The laboratory tests undertaken include particle density, moisture content, organic content, Atterberg limits, particle-size distribution, proctor compaction, California Bearing Ratio (CBR) and consolidation tests. Geotechnical laboratory tests were carried out on untreated biosolids as well as biosolids stabilised with 1%, 3% and 5% by weight of cement and lime. The test results were subsequently compared with the existing local road authority specification for embankment fill material.