Introduction and background

Introduction and background

The understanding of the fate and transport of contaminant plumes from contaminated sites in limestone aquifers is important because they are a major drinking water resource. This is challenging because they are often heavily fractured and contain chert layers and nodules, resulting in a complex flow and transport behavior. Different field methods have been developed to quantify the flow field and transport behavior in such aquifers and to estimate the contaminant distribution. This wiki will give an overview of some useful methods for fractured limestone aquifer. Modeling can be a useful tool for the interpretation of measurements and for the prediction of the contaminant behavior in the aquifer. It can be used as a tool to advance the conceptual understanding and for decision support for risk assessment and the planning and assessment of remedial actions.

Several fracture flow and transport models are available for the modeling of contaminant transport in fractured media. This wiki aims at giving an overview of modeling tools that can be used for the interpretation and prediction of flow and transport processes in fractured limestone aquifers. The focus is on chlorinated solvents (PCE, TCE etc.) as contaminants. The different modeling concepts are presented in the chapter Model concepts. They will be compared for their suitability to simulate field data and to represent typical features of fracture flow and transport using a field example (Example: Akacievej). Furthermore, it will be exemplified how to establish a conceptual model for a contaminated site. The steps how to build up a suitable numerical model will be described.

Physical processes

Advection, diffusion and dispersion, fracture flow, sorption and retardation

Flow

Groundwater flow in porous media is usually described by Darcy's law, giving a relation between hydraulic head gradient and groundwater flow. Flow equation.

Contaminant transport

Transport equation

Properties of limestone

Borehole cores from the Akacievej field site.

Low conductive matrix - can be heavily fractured - chert layers and nodules - sorption behavior for chlorinated solvents

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