Numerical Modeling of Head Losses in Different Types of Well Screens.

Quantifying total well loss through well screens has been traditionally undertaken through experimentally based empirical equations or equations derived for water flow through (circular) orifices. Advances in computer capacity enables incorporation of CFD formulations at millimeter scale, coupling Darcy flow and Reynolds Averaged Navier Stokes (RANS) to better understand and quantify processes related to well loss for different screen types. This study provides a methodology of quantifying well screen head loss using numerical models, coupling Darcy flow (aquifer and filter/gravel pack) with turbulent flow (in-well and through screen) at a sub-millimeter scale.

Estimates of Horizontal Groundwater Flow Velocities in Boreholes.

Currently, monitoring tools can be deployed in observation boreholes to better assess groundwater flow, flux of dissolved contaminants and their mass discharge in an aquifer. The relationship between horizontal water velocity in observation boreholes and Darcy fluxes in the surrounding aquifer has been studied for natural flow conditions (i.e.

Towards optimal sampling schedules for integral pumping tests.

Conventional point sampling may miss plumes in groundwater due to an insufficient density of sampling locations. The integral pumping test (IPT) method overcomes this problem by increasing the sampled volume. One or more wells are pumped for a long duration (several days) and samples are taken during pumping.

Investigation of sewer exfiltration using integral pumping tests and wastewater indicators.

Leaky sewers affect urban groundwater by the exfiltration of untreated wastewater. However, the impact of sewer exfiltration on the groundwater is poorly understood. Most studies on sewer exfiltration focus on water exfiltration, but not on the impact on groundwater quality.

Integral quantification of contaminant mass flow rates in a contaminated aquifer: conditioning of the numerical inversion of concentration-time series.

A series of integral pumping tests (IPTs) has been conducted at a former gasworks site to quantify the contaminant mass flow rates and average concentration in groundwater along three control planes across the groundwater flow direction. The measured concentration-time series were analysed numerically with the help of the inversion code CSTREAM and a flow and transport model representing the highly heterogeneous aquifer. Since the control planes cover the entire downstream width of the potentially contaminated area, they allow conclusions to be drawn about the current location and spread of the contaminant plume.

Comment on "Analysis of groundwater contamination using concentration-time series recorded during an integral pumping test: Bias introduced by strong concentration gradients within the plume" by Allelign Zeru and Gerhard Schäfer.

We consider the results of a recent paper in this journal [Zeru, A. and Schäfer, G., 2005.

Monitoring groundwater contamination and delineating source zones at industrial sites: uncertainty analyses using integral pumping tests.

Field-scale characterisations of contaminant plumes in groundwater, as well as source zone delineations, are associated with uncertainties that can be considerable. A major source of uncertainty in environmental datasets is due to variability of sampling results, as a direct consequence of the heterogeneity of environmental matrices. We develop a methodology for quantifying uncertainties in field-scale mass flow and average concentration estimations, using integral pumping tests (IPTs), where the contaminant concentration is measured as a function of time in a pumping well.