WDA Consultants Inc.

Industrial waste disposal site Münchehagen: Confinement of dissolved contaminants by discharging saline water

K.U.Weyer, Ph.D., P.Geol. and D. A. van Everdingen, Ph.D.
WDA Consultants Inc., 4827 Vienna Drive NW, Calgary, Alberta, Canada

© 1995 WDA Consultants Inc.


Subsurface migration of contaminants is primarily a function of groundwater flow direction. The main constraints to groundwater flow are the configuration of the groundwater table and the distribution of variously permeable subsurface layers. In response to these parameters and thermodynamic constraints distinct local, intermediate, and regional groundwater flow systems co-exist.

Contamination in one flow system normally cannot migrate into another flow system. Thus groundwater dynamics are an efficient means to determine the direction and endpoint of contaminant migration and to predict which parts of the subsurface will remain untouched by a migrating contaminant.

The thermodynamic position and configuration of all parts of a groundwater flow system are integrally related. The regional, often saline, flow system, bounded by the groundwater surface, determines and contains the configuration of local groundwater flow systems.

The configuration of groundwater flow and contaminant migration at the Münchehagen (Germany) waste disposal site is an excellent example of how regional groundwater flow can, near regional discharge areas, restrict the migration of dissolved contaminants within a local groundwater flow system.

At Münchehagen regional discharge of saline water effectively confines the migration of dissolved contaminants to the limited volume of the local flow system. The regional flow system originates in the Rehburg Hills, some 7 km away, and penetrates 800-900 m into evaporitic layers before discharging saline water [spec. conductivity 55000 µS/cm; density = 1.026 g/cm3] into the channel of the river Ils. In accordance with the hydrodynamic principles of potential theory an approximate solution of this variable density flow has been calculated with a cross-sectional mathematical model.

The model reflects to a remarkable degree the extensive hydrodynamic and hydrochemical measurements from the site. At Münchehagen, dissolved contaminant migration is confined to a limited part of the subsurface by the regional flow of saline water within the thermodynamic entity of the overall groundwater flow system.

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