Integrated geophysical and atmogeochemical survey applied to abandoned soviet military areas contaminated by LNAPL in the Czech Republic
by
Stanislav Mares
Charles University of Prague, Dept. of Applied Geophysics, Albertov 6, CZ-12843 Praha 2, Czech Republic
Coauthors: Jiří Kvapil, Jaroslav Kněz, Jiří Dohnal, Zdeněk Jáně, Ladislav Zima

Two different geoelectrical models must be considered in the case of Light Non-Aqueous Phase Liquids (LNAPL) contaminating soil and groundwater: a) short time residence of hydrocarbons in the soil (up to several months after the accident), b) long time residence of hydrocarbons in the soil (several years or decades of years). In the latter case, changes in physical properties of the rock medium caused by the biodegradation processes must be taken into account what has consequences for the application of geophysical methods. The hydrocarbon contamination of abandoned soviet military areas in the Central and Eastern European countries has a typical character of long time residing organic pollutants in the soil medium.

During last years a series of papers was devoted to possibilities of geophysical methods in detecting long time residing LNAPL plumes in the granular sediments. Sauck (2000) developed a new conceptual geophysical model for this case taking into the account geochemical processes caused by the bacterial biodegradation of hydrocarbons. The existence of the low resistivity zone below the LNAPL plume is the only chance to estimate indirectly the extent of the plume by resistivity survey (multielectrode measurements, vertical electrodes) and ground penetrating radar. Cone penetration tests combined with logging of penetration holes enable the direct detection of LNAPLs in the vertical section of sandy aquifers. We combined the geophysical techniques with the soil vapour survey using the new method and instrumentation (Ecoprobe 5) based on the combination of photo-ionisation and selective infra-red analysers. The efficiency of this approach is documented on materials from an abandoned military area in the northern part of the Cretaceous of Bohemia built by sandy sediments with relatively low content of clayey particles. The area is of great interest from the hydrogeological point of view being a part of the infiltration area for Middle Turonian sandstones - important aquifer supplying drinking water to some communities in the southern part of the Cretaceous basin.

Date received: July 12, 2004

Copyright © 2004 by the author(s). The author(s) of this document and the organizers of the conference have granted their consent to include this abstract in Atlas Conferences Inc. Document # caon-07.