April 2002 Meeting Abstract
Engineered technologies like pump-and-treat and iron reactive walls are becoming more effective at treating contaminants from groundwater. Unfortunately, the cost of operating, maintaining, and replacing these types of systems over the length of time required for remediation, often on the order of a century or more, represents an increasing portion of the total remedial budget. In the past 5 years, remedial strategies are being re-evaluated to determine whether traditional engineered systems can be replaced by simpler, effective, and more cost-sensible alternatives that achieve regulatory objectives. Remediation experts are also realizing that source remediation of contaminants that form dense, non-aqueous-phase liquids (DNAPLs) is difficult and is limited by the rate of desorption of these contaminants from the substrate into the soluble phase.
Wetlands have long been considered nature's "kidneys." These complex ecosystems naturally contain interdependent physical, chemical, and biological processes that can effectively remove many pollutants. These processes (microbial degradation, mixing, adsorption, precipitation, dilution, volatilization, and phytoremediation) act singly or together to remove different types of organic and/or inorganic contaminants. Wetland habitats are particularly well suited to natural attenuation of organic compounds including DNAPL-forming compounds such as trichloroethene (TCE) and its degradation products. Wetlands are slow moving, nutrient-rich environments high in organic carbon, where a dense and diverse community of wetland microorganisms can thrive. Wetlands are better suited to microorganisms than groundwater aquifers - where most of the recent studies concerning natural attenuation have focussed.
Ecology & Environment, Inc. (E & E) has performed bench-scale and full-scale pilot studies to measure the effectiveness of using constructed treatment wetland technology to passively capture and degrade a groundwater-contaminant plume, composed predominantly of TCE and its degradation products, cis-1,2-dichloroethene and vinyl chloride. The theory behind this remediation concept, as well as results of these studies, will be presented. A general introduction to the constructed treatment wetland technology will also be provided.
Tom Ferraro, principal hydrogeologist with E & E in Buffalo, New York, will give this presentation. Tom has worked as a professional geologist for the last 25 years. He holds a master's degree in geology from Oklahoma State University and a bachelor's degree in geology from James Madison University.
See you there.
Lea Cervi
Executive VP