--> ABSTRACT: Geochemical Consequences of Deep-Well Injection of Hazardous Wastes, by Rodney A. Crother, Matthew W. Totten; #91020 (1995).

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Geochemical Consequences of Deep-Well Injection of Hazardous Wastes

Rodney A. Crother, Matthew W. Totten

EPA and other local agencies commonly grant exemptions to the ban on land disposal of hazardous wastes when the operators claim injected wastes will be structurally, hydrologically, and stratigraphically isolated from fresh-water aquifers for at least 10,000 years. A major factor in the prediction of this prolonged isolation is the physical characteristics of the formation that is receiving the waste. Some of these characteristics such as porosity and permeability directly affect the ability of the reservoir aquifer to store injected waste. Injection of liquid waste into deeply buried aquifers can cause unforeseen chemical changes to the waste or the aquifer due to the elevated temperatures and pressures found in the deep subsurface. These injection wells frequently exhib t increased injection pressures, probably because of decreases in the porosity and/or permeability.

By using a dynamic flow-through reaction vessel, cores of the injected formation can be subjected to simulated subsurface conditions. Hazardous waste solutions are then injected into these cores, and resulting changes in the porosity and permeability can be measured.

Laboratory tests show that the organic chemicals flowing through deeply-buried aquifers (simulated 1800 m, 60° C, 100 bars) for as little as one week will hydrolyze and form gel-like substances that can cause a substantial loss of porosity and permeability.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995