30    CONTROL OF METHANE FROM MUNICIPAL SOLID
WASTE LANDFILLS BY INJECTION
OF LIME AND FLYASH
Riley N. Kinman, Professor
Janet Rickabaugh, Research Associate
Martha Lambert, Research Associate
Dept. of Civil and Environmental Engineering
University of Cincinnati
Cincinnati, Ohio 45221
David L. Nutini, General Manager
RNK Environmental, Inc.
Covington, Kentucky 41011
INTRODUCTION
Pressure injection grouting of lime slurry has been used for a variety of purposes. In recent years
this technique has been used with lime/flyash slurries for prevention of methane gas formation and
stabilization at sanitary landfills. In the landfills the grout is injected such that all or most of the void
space is filled with the slurry. This should have a twofold effect. First, since the flyash will set into a
cement-like substance there will be an overall increase in strength of the area and a subsequent
decrease in settlement of the landfill. Second, the massive dose of lime added should raise the pH of
the fill resulting in an environment inhospitable to those microorganisms necessary for the production
of methane. Little laboratory data exist for evaluation of this lime or lime/flyash injection method to
prevent methane formation. However, limited field data suggest that this method has been successful
in increasing the strength of a fill and in preventing methane formation.1 Since the conclusion that
methane generation was prevented was based upon indirect measurements {i.e. after lime/flyash
injection measurable quantities of methane were not found in a building that had measurable quantities of methane prior to injection) there is some question whether methane generation has actually
been prevented, retarded or simply deviated to some other area in the field site. Furthermore, since
field applications of this method have simply injected as much lime/flyash slurry as possible there is
no indication of the actual amount of lime slurry needed to prevent methane gas generation. Due to
the difficulty in developing a reliable methane collection system it is not practical to answer these
questions at a field site. Therefore, six experimental sanitary landfills housed in the USEPA Center
Hill Solid and Hazardous Waste Research Facility in Cincinnati, Ohio, were injected with lime or
lime/flyash mixtures to evaluate this procedure for methane prevention. This report describes the
procedures used and the results obtained over the 17 months of this project.
Background
In January, 1980, the Department of Energy initiated a project designed to study methods of
generating a higher quality and quantity of methane for use as an energy source. Sixteen laboratory
scale lysimeters were loaded with shredded municipal refuse. The 16 cells were paired, with each pair
receiving a different gas enhancement technique. The enhancements investigated included moisture
addition, elevation of temperature, leachate recycle, sewage sludge addition, buffer addition, and
nutrient addition. Several years into the project the Gas Research Institute took over the study at
which time one of each of the original pairs of cells received an additional enhancement. After five
years of data collection the gas enhancement project was terminated and 10 of the 16 test cells were
dismantled in a USEPA project designed to characterize the quality of the gas produced and to gather
information on the types of organisms that were active within the municipal solid waste. The remaining six test cells were then used as the experimental landfills for this lime injection project.
43rd Purdue Industrial Waste Conference Proceedings, © 1989 Lewis Publishers, Inc., Chelsea, Michigan 48118.
Printed in U.S.A.
239