Summary of Studies for

Richard Statom, Fiessinger Scholarship Winner 2001

(Report - summer 2002)

The contamination of groundwater by leachate from municipal solid waste landfills is a well-documented phenomenon that is found throughout the world.  The remediation of groundwater at these facilities can involve a variety of technologies, depending on factors such as the type, concentration, and physical extent of the contamination.  A remediation alternative that has gained popularity in recent years is known as natural attenuation.  Natural attenuation is the reduction in concentration of contaminants in groundwater by natural processes.  These processes can be geochemical and biological, and are dependent on factors such as the cation exchange and sorption capacity of the aquifer material, dilution, the microbial population, microbial carbon sources and nutrients, and the type and quantity of the contaminant to be attenuated.

Landfills can be continuous sources of contamination for many years, therefore, in order to evaluate an aquifer’s capacity for natural attenuation of groundwater contamination from landfill leachate, the chemical characteristics of the leachate need to be defined for the present and the future.  Prediction of future changes in leachate chemistry usually requires the use of a geochemical model, and such models should be calibrated to actual data before employed in a predictive mode.  Thus, the monitoring of leachate chemistry and evaluation of the data over the life of a landfill is needed to formulate and calibrate a model that can make long-term predictions on the nature of the leachate. 

In general, previous studies conducted to determine the temporal changes in leachate chemistry were based on simulated landfill cells, small numbers of lysimeters, or landfills of different ages involving relatively short (4 years or less) sample periods.  In this phase of my research, over 12 years of quarterly leachate chemistry data from a lined landfill cell in Florida was investigated and the changes in concentrations of various parameters that are commonly analyzed by landfill operators were evaluated.  By analyzing the data from a single landfill cell over an extended period of time, the variability of factors inherent in studying simulated landfills and landfills of different ages (such as geography, climate, waste composition, landfill volume, geometry, and moisture content) are not a concern, and do not complicate the analysis of the influence of landfill age on leachate chemistry.

This line of research has already revealed some interesting temporal trends in leachate chemistry, including decreasing concentrations for many parameters with increasing landfill age, covariance of several parameters over time, and the apparent affect of closure of the landfill on leachate chemistry. 

A preliminary report of this investigation was presented at the 2002 Rocky Mountain Section of the Geological Society of America meeting and is listed in the GSA Abstracts.  The final report will be presented at the 2002 Annual meeting of the Geological Society of America in Denver, Colorado in late October.

Publication List for Richard A. Statom (Landfill related)

Statom, R., 1997. Lantana Landfill: A history of environmental management 1965-96.  Proceedings of the 22^nd Annual Conference of the
     National Association of Environmental Professionals, 877-886

Maliva, R., Missimer, T., Leo, K., Statom, R., Dupraz, C., Lynn, M., Dickson, J., 2000.  Unusual calcite stromatolites and pisoids from a landfill
     leachate collection system. Geology, 28(10), 931-934 

Statom, R., A., Thyne, G., McCray, J., E., 2002.  Temporal changes in leachate chemistry of a municipal solid waste landfill in florida.  Geological
     Society of America Programs and Abstracts, 34(4) A46