CLAY BEDS FOR STORING SOLID INDUSTRIAL WASTES-
A SURVEY
Robert L. Sanks, Professor
Department of Civil Engineering
Montana State University
Bozeman, Montana 59715
Earnest F. Gloyna, Dean
College of Engineering
The University of Texas
Austin, Texas 78712
INTRODUCTION
Much of the land area in the southern United States is underlain by massive clay formations, many of which would be ideal repositories for industrial wastes if their performance characteristics could be predicted.   Clay has many advantages for sequestering
wastes.   It often occurs in thick, massive beds, and it is very impermeable.   Most clays
have high adsorptive capacities and have considerable cation exchange capacities.   The
large buffering capacity of the clay is capable of neutralizing acids and bases.   The carbonate associated with clay is available for the precipitation of heavy metals.   And, finally, a
rich population of bacteria from surface layers can provide biochemical destruction of
pollutants.   Landfills designed for minimum moisture movement reduce the driving force
for movement of pollutants.   The total result is a passive barrier which contains many effective mechanisms.
On the other hand, there are some disadvantages in using clay.   It is difficult    to obtain good engineering data for design.   Even the measurement of permeability is very difficult.   In its undisturbed state, the permeability of clay is so low that realistic measurements of adsorption or ion exchange may require months or years.   Clays shrink and swell
excessively with moisture changes and control of dimensional changes is difficult during
construction.   Clays tend to crack as they dry and the cracks can penetrate many feet
deep, so the integrity of a completed repository may be undermined.   Continual, long-
term monitoring after the repository has been filled and the site abandoned may be difficult to ensure.   These problems are compounded by the number and variety of chemicals
buried.   Other methods have been proposed and some are in limited use, but landfills will
continue to be the most practical solution for many years.
OBJECTIVES
The aim of this study was to explore the state-of-the-art and the suitabdity of using
clay basins for storing a few selected wastes.   More specifically, the objectives were to
develop test procedures for measuring pollutants, to discover the factors that affect repeatability and accuracy, to assess the suitability of clay, and to develop rational design
procedures.
The limitations of funds and time precluded more than a survey, and consequently the
work was limited to batch tests of five selected clays and industrial wastes represented by
hydrochloric acid, caustic, four organics (phenol, acetone, acetaldehyde, and benzene),
five heavy metals (arsenic, chromium, mercury, lead and zinc) and one pesticide, DDT.   The
batch tests were utilized to select three clays (Beaumont, Catahoula and Eagle Ford) and
five wastes (acid, base, phenol, lead and mercury) for column tests.
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