Formatted Title
Integrating Multi-Source Data for Targeted Remediation of Long-Term Chlorinated Solvent Contamination in Groundwater: A 3-D Geospatial Approach
Background/Objectives
The identification of the contamination source and plume in a site-specific hydrogeological context is a key element for interpreting contamination dynamics and designing and implementing targeted remediation strategies adapted to the site-specific hydrogeochemical and physical characteristics. This study presents a comprehensive remediation project for a site contaminated long-term by chlorinated solvents in groundwater, focusing on the identification of the contamination source, the reconstruction of the conceptual site model (CSM), and the design of the remediation strategy. The research integrates various data sources, including geological boreholes, groundwater monitoring points, and membrane interface probe (MIP) data, for the step-by-step reconstruction and refinement of a multi-source and geology-focused CSM that unveils the mechanisms of pollutant migration in groundwater and guides the deployment of a remediation strategy in line with the principles of remediation geology.
Approach/Activities
A geospatial data geodatabase collected information from 113 geological boreholes and 184 groundwater monitoring points. The data, collected between 2005 and 2023, included information on stratigraphic contacts, piezometric measurements, and chemical analyses. Permeability tests and pumping tests were conducted to obtain aquifer parameters. MIP techniques provided high resolution vertical profiles of subsurface contamination levels. Geomodeling operations guided by the geodatabase aimed to generate a 3-D hydrogeophysical model capturing site-specific hydrogeochemistry, identifying the contamination source within the stratigraphic context, defining groundwater flow patterns and preferred pathways of flow and transport guided by the hydraulic gradient and subsurface stratigraphic discontinuities. Data-driven modeling influenced the design of a groundwater recirculation barrier intervention with groundwater circulation wells (GCW) to intercept and treat the plume.
Results/Lessons Learned
The 3-D multi-source model overlays and depicts both the source distribution and the contamination plume in a georeferenced space, with geometries strongly influenced by site hydrogeology, mobility, and physico-chemical characteristics of the contaminants. The configuration of the virtual recirculation barrier reflects the need to target the contamination plume originating from the source identified by the CSM. Traditional hydrochemical monitoring coupled with multilevel sampling validates the interception of the contamination plume by the groundwater recirculation barrier. The study demonstrates the effectiveness of this multi-source approach in conceptualizing the distribution of contamination plumes originating from sources and integrating them into the geological framework. The results also highlight the potential of GCWs in a barrier configuration in intercepting the contamination plume, mobilizing contaminants within the aquifer, and achieving decontamination. The findings contribute to a sustainable and data-driven remediation strategy for contaminated sites.