Abstract

Most contaminated site investigations still rely on conventional characterisation approaches based on collecting a limited number of soil samples and installing long-screened wells. However, it is widely recognised that these methods cannot adequately capture the subsurface heterogeneity largely governing the fate and transport of contaminants. Following the example of cone penetration testing (CPT), multiple direct-push profiling tools have been developed over the years to investigate and manage contaminated sites in a more efficient and sustainable way. The objective of this work is to present well-established and emerging direct sensing technologies for contaminated site investigation and demonstrate how their application does not just result in a reduction of uncertainties but also in improved sustainability outcomes. The assessed technologies included the Hydraulic Profiling Tool (HPT), laser-induced fluorescence (LIF), Membrane-Interface Probe (MIP), and nuclear magnetic resonance (NMR). Direct-push profiling techniques were found to be valuable throughout the project lifecycle, from initial site screening phases to remedial design and closure. The high-density data collected helped to delineate contaminant source zones, preferential migration pathways and low-permeability zones. This information complemented the analysis of a reduced number of physical samples to optimise remedial designs and monitoring networks. Additional benefits related to sustainability concepts included the production of minimal investigation-derived waste, the need for less field campaigns and the little impact caused to site owners and their activities. High-resolution site characterisation approaches are paramount to conduct informed risk assessments and effectively achieve remediation goals.