Time variyng groundwater flux measurement using a single well tracer technique

Poster (2013, April 24)

Contaminant mass discharge measurements are often performed at given times or integrated over a certain period of time, using active or passive sampling techniques. One problem arising is that such ... [more ▼]

Contaminant mass discharge measurements are often performed at given times or integrated over a certain period of time, using active or passive sampling techniques. One problem arising is that such measurements may not be representative of the temporal dynamics of the mass discharge variations. These variations can be caused by fluctuations in contaminant concentrations or, more frequently, by changes in the groundwater fluxes. Pollutant mass fluxes are typically estimated through a combination of solute concentrations and groundwater fluxes measured across a control plane made of several multi-level wells. Accurate measurements of local transient Darcy fluxes have been recognized as the weakest points in most of the developed techniques for groundwater contaminant mass flux measurements. The main objective here is to extend the FVPDM technique for temporal monitoring of groundwater fluxes and to demonstrate its ability to be used in combination with passive sampling devices for measurement of contaminant mass fluxes in groundwater. The Finite Volume Point Dilution Method (FVPDM) is a single well tracer technique for the measurement of local groundwater fluxes based on the continuous injection of tracer at very low injection rate (Brouyère et al. 2008). These developments are based on the application of the adapted technique on a case study in a fractured granitic aquifer in Ploemeur (France). This application investigates transient groundwater fluxes that are controlled by pumping in a well nearby the tested piezometers. Long monitoring time series have been recorded under these controlled conditions of transient groundwater flow. Results show the high sensivity of the FVPDM technique to small variations in groundwater flow velocities and its aptitude for long term monitoring of groundwater fluxes. The comparison between the results of FVPDM and classical point dilution tests performed in same conditions shows close correlation. Interpretation of FVPDM tests in transient conditions have been developed together with an evaluation of the uncertainties that can happen if the frequency of the groundwater flow variations is high. The tests carried on the Ploemeur site also illustrate the first ever application of the FVPDM technique between a double-packer system used for the investigation of a defined layer of an aquifer. This innovative application of the FVPDM using packers opens concrete perspectives for investigation of vertical heterogeneities of groundwater fluxes across a well. [less ▲]

Modélisation régionale des eaux souterraines dans le cadre de la mise en œuvre de la Directive Cadre sur l’Eau : exemple du projet Synclin’Eau

Conference (2012, October 10)

Flux-based Risk Assessement of the impact of Contaminants on Water resources and ECOsystems

Report (2012)

Quantification and monitoring of contaminant mass fluxes in heterogeneous subsurface media

Poster (2011, May 26)

Since the beginning of the years 2000, a consensus has been growing among the scientific, technical and decision makers community concerning the fact that the characterisation and the management of ... [more ▼]

Since the beginning of the years 2000, a consensus has been growing among the scientific, technical and decision makers community concerning the fact that the characterisation and the management of contaminated sites have to be performed in terms of contaminant flux metrics instead of to be based on a simplistic study of pollutant concentration coming from piezometers randomly spread over the site. Contaminant plumes and associated pollutant mass fluxes are extremely variable in space as well as in time. The scientific and technical challenge is to capture this double heterogeneity in order to consider it explicitly or statistically for the management of a contamination issue. This requires (1) the interception of the entire contaminated groundwater flowing section with a control panel; (2) the ability to measure and to calculate accurately groundwater and contaminant fluxes across that panel; and (3) the repetition of the measurement to bring out the spatial and the temporal variation of contaminant fluxes. This research project aims to develop an integrated pollutant flux measurement approach for contaminated groundwater at the scale of the contaminant plume. This approach lays on a triple integration of (1) single well tracing techniques – (2) passive sampling – (3) control panel. Spatial and temporal variability of groundwater fluxes will be quantified by the point dilution tracing method derived from the “FVPDM” technique (Brouyère et al. 2008). In the same time, the amount of pollutant flowing through the same location will be determined by the adequate passive sampling technique (PS). The integration of these two measures in an interpretation schema based on mathematical and numerical modelling will allow quantifying contaminant fluxes and their variability over time. The adaptation at the scale of the contaminant plume will be based on a logging-type use of techniques, repeated along the vertical axis of the monitoring wells and repeated from one well to an other of a control panel implanted to intercept the plume. All the research results and developed techniques will then be integrated into a complete measurement system (PS-FVPDM), mobile and easily usable on field. The whole development and testing will take place on several pilot contaminated test site located in various hydrogeological context. [less ▲]

Captage de Pêchet: Etude hydrogéologique en vue de préciser l'extension des zones de prévention

Report (2011)

Hydrogéologie du bassin du Samson

in Michel, Georges; Thys, Georges; De Broyer, Claude (Eds.) Atlas du Karst Wallon. Bassins du Bocq et du Samson (2011)

Ce chapitre décrit l'hydrogéologie du bassin du Samsonvdans la partie "articles thématiques" de l'Atlas du karst consacré aux bassins du Bocq et du Samson. Après une description générale, la nature et les ... [more ▼]

Ce chapitre décrit l'hydrogéologie du bassin du Samsonvdans la partie "articles thématiques" de l'Atlas du karst consacré aux bassins du Bocq et du Samson. Après une description générale, la nature et les potentialités aquifères du bassin du Samson sont abordées : les unités hydrogéologiques sont décrites, des aspects quantitatifs et des bilans hydrogéologiques sont détaillés et des aspects qualitatifs sont développés. [less ▲]

A regional flux-based risk assessment approach of contaminated sites on groundwater bodies

Poster (2010, April 22)

In the context of the water framework directive, management plans have to be set up about water quality in surface and groundwater bodies in the EU. One of the first steps is to evaluate the risk of ... [more ▼]

In the context of the water framework directive, management plans have to be set up about water quality in surface and groundwater bodies in the EU. One of the first steps is to evaluate the risk of contamination of these water resources, and particularly the risk posed by contaminated industrial sites. From the perspective of water resource management, each of these sites taken individually does not necessary constitute a major threat. However, in heavily industrialised and urbanised areas, the cumulative effect of multiple contaminant sources is likely to present a risk. In order to propose adequate but still economically reliable measures, the calculated risk should be based on a so-called megasite approaches using criteria reflecting the water quality deterioration, in a cumulative way, at the scale of the whole surface water or groundwater body. A GIS-based regional risk assessment approach is developed here for groundwater bodies using the SEQ-ESO currently used within the Walloon Region as indicator to reflect the quality status of the groundwater body. The approach is applied on the groundwater body RWM073 “Gravels and alluvial deposits of the Meuse river between Engis and Herstal”, identified at risk of not reaching a good quality status by 2015. The different steps of this methodology consist of an inventory of proved or potential contaminating industrial sites, a numerical modelling of pollutants behaviour at the scale of the groundwater body and the application of the SEQ-ESO that finally gives a global quality status of the whole groundwater body. This analysis also serves as basis for a socio-economic approach intending to provide indications on costs and benefits generated by total or partial remediation of the contaminated groundwater bodies according to the different management scenarios. [less ▲]

Délivrable 1 : Plan de travail et méthodologies pour l’exécution des différentes activités de la convention A du projet

Report (2009)

Caractérisation hydrogéologique et support à la mise en œuvre de la Directive Européenne 2000/60 sur les masses d’eau souterraine en Région Wallonne (Projet Synclin’EAU) : délivrable D.3.12 Rapport sur la caractérisation hydraulique des aquifères et l'estimation des ressources en eaux souterraines – partie RWM011. Convention RW et SPGE-Aquapôle

Report (2009)

Caractérisation hydrogéologique et support à la mise en œuvre de la Directive Européenne 2000/60 sur les masses d’eau souterraine en Région Wallonne (Projet Synclin’EAU) : délivrable D.3.12 Rapport sur la caractérisation hydraulique des aquifères et l'estimation des ressources en eaux souterraines – partie RWM012. Convention RW et SPGE-Aquapôle

Report (2009)