LAND DISPOSAL OF CHEMICAL SLUDGE
Nicholas Scambilis, Lieutenant Colonel
U.S. Air Force
Headquarters, Strategic Air Command
Engineering Services, Environmental Quality Division
DEVQ, Offutt Air Force Base, Nebraska 68113
John Novak, Associate Professor
University of Missouri—Columbia
Columbia, Missouri 65201
INTRODUCTION
The purpose of this investigation was to determine testing procedures to be used for
the evaluation of the effects of chemical sludges on soils.   The chemical sludges used in
this study were the by-products of water treatment processes and the residues from coal-
burning power production plants.
The disposal of chemical sludges from water treatment plants and coal-burning power
plants is not a new problem.  The majority of water treatment plants dispose of their
solids by returning them to surface waters.  The power plants dispose of their scrubber/fly
ash solids by dumping the dried residues in sanitary landfills.   Under recently enacted federal and state legislation, however, these wastes are generally considered pollutants.  Current legislation prohibits the disposal of water plant by-products and pollutants to certain
small streams and rivers.   For large rivers, such as the Missouri River, disposal of water
plant by-products is not prohibited.   Investigations are, however, currently being conducted
to determine the effect of water plant by-products on the overall river water quality.
The disposal of power plant residues in sanitary landfills causes, under anaerobic conditions, the release of heavy metals.  These heavy metals are leached through the landfill
and eventually reach the ground water.   In areas where the ground water is the major
source of water supply, the heavy metals would be a source of pollution.   The disposal of
the residues on sanitary landfills could therefore become prohibitive.
Chemical sludges from water plants and power plants are highly variable in composition.
These sludges are produced continuously but are discharged intermittently.   Since the wastes
from each plant are different, no specific treatment process will yield the same results.   Experience in the disposal of these wastes has been very limited.   Even more limited, however,
has been the experience in the disposal of these wastes when using the soil as a disposal
medium.
The evaluations and predictions determined in this investigation are viewed from three
closely related disciplines:   namely, soil mechanics, soil science and sanitary engineering.
Even though the effects of the sludges on the soil are similar for all three disciplines, the
tests to evaluate their effects differ.  Specifically, the soil mechanics discipline looks at the
effect of sludge on the soil structural properties; the soil science discipline looks at the
effects on the soil agricultural properties; and the sanitary engineering discipline looks at
the effects on the environment.
MATERIALS AND METHODS
Materials
Four common Missouri soils, two topsoils and two subsoils, and four chemical sludges
were selected for use in this study.  The soils were selected for their varying properties
272