Multidisciplinary monitoring of an in-situ remediation test of chlorinated solvents

Pollutions on and within the underground poses risks for groundwater contamination and is a widespread global problem. Common remediation methods based on digging and removal can be expensive and have limitations, while in-situ remediation is an attractive alternative. However, there is a need to develop tools to monitor the effectiveness both in terms of the successful injection of remediation fluids but also the effectiveness of the treatment, i.e., degree of degradation/removal of the pollutants and possible metabolites. This paper presents a methodology for monitoring the changes following an in-situ remediation treatment of a site contaminated with chlorinated solvents. The methodology consists of two different methods, where Direct Current resistivity and time-domain Induced Polarization (DCIP) was used to acquire daily data and geochemical analyses on water samples were collected approximately every three months. The geophysical results provide insights on how the injected fluids are spreading and assist in acquiring a better understanding of the geological and hydrogeological system. On the other hand, the geochemical sampling enhances our knowledge about the hydrochemistry of the system and the concentration of the pollutants. Our research highlights the challenges of monitoring in-situ bioremediation experiments in complex environments and in cases where pollutants are situated in low hydraulic conductivity formations. The joint interpretation of the data shows the importance of an interdisciplinary approach to understand complex systems.

An overview of in situ testing and geophysical methods to investigate municipal solid waste landfills

Municipal solid waste (MSW) management is challenging as a whole. Global waste generation is expected to continue to increase in the coming years, and landfills are currently the primary destination. Therefore, the stability of these structures must be carefully evaluated to prevent failures and associated health and pollution risks, which implies the determination of waste properties using more reliable approaches. This paper presents a scoping review of field data from MSW landfills and outlines suggestions for future work. Studies published in the past twenty years were selected following a systematic search process in databases. Aspects discussed include (1) strength parameters and soil behavior type from in situ testing, (2) elastic moduli from seismic wave propagation, and (3) moisture content from geoelectrical measurements. Although the values of geotechnical parameters have varied due to waste heterogeneity and applied methods, the trends observed with depth and age could be compared. Research opportunities involve the spatial analysis of mechanical properties at a given site, seismic response of landfills with high organic content and saturation degree, interpretation of long-term resistivity monitoring, and combination of electrical properties to assess the degradation stages within the waste mass.

Groundwater potential zonation using VES and GIS techniques: A case study of Weserbi Guto catchment in Sululta, Oromia, Ethiopia

Groundwater is an appreciated and vital natural resource in the world, and it is of the utmost essential for the growth and development of a country. Nevertheless, assessing the groundwater potential and its recharge region is still ambiguous due to the nature of groundwater. In this study, the groundwater potential of the Weserbi Guto Laga Qawe Catchment Sululta area was assessed using VES and GIS methods. For the model, thematic layers were generated from the geophysical investigation, existing maps, and field survey results and were integrated into the GIS environment to delineate the groundwater potential zones. Factors such as lineament density, drainage density, elevation or topography, slope gradient, aquifer resistivity, and lithology were derived, reclassified, and scaled to common ranges and assigned with appropriate weights. The groundwater potential zonation model of the site was produced by the multicriteria evaluation method. Accordingly, the geometrical interval method was utilized to classify the index into three zones (high, moderate, and low) to produce the map. The model result revealed that a large part of the study area fell into the high zone with 50.14 % (3669.99ha). whereas 35.85% (262.72ha) and 14.01% (1024.95ha) show moderate and low groundwater potential, respectively. The resulting map was validated using eleven existing water level data points and the result was found to be in good agreement with the model.