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DESIGN AND OPERATION OF A HORIZONTAL WELL, IN SITU BIOREMEDIATION SYSTEM
Citation:
Weesner, B., S Acree*, T. McAlary, AND J. J. Salvo. DESIGN AND OPERATION OF A HORIZONTAL WELL, IN SITU BIOREMEDIATION SYSTEM. First International Conference of Chlorinated and Recalcitrant Compounds, Monterey, CA, 5/18-21/1998.
Description:
A large field demonstration using nutrient addition to stimulate insitu anaerobic bioremediation of chlorinated solvent contaminated soil and ground water was performed at the former U.S. Department of Energy Pinellas Plant in Largo, Florida, from January through June, 1997. Insitu anaerobic bioremediation was evaluated after recommendation by participants in the Innovative Treatment Remediation Demonstration (ITRD) Program, as an innovative technology that could accelerate the removal and destruction of chlorinated volatile organic compounds (VOCs) in a sandy, shallow, anaerobic aquifer at the Northeast Site.
Laboratory batch and column studies conducted through the ITRD Program using site soil and ground water showed that a population of anaerobic microorganisms existed capable of remediating the chlorinated contaminants of concern. These studies suggested that contaminant degradation could be significantly enhanced by the addition of nutrients such as benzoate, lactate, and methanol. Therefore, the challenge of the design and operation of the field bioremediation demonstration was to insure proper nutrient delivery to the treatment area.
System design required a relatively accurate characterization of site contamination and ground water flow directions and rates since the study area included about four soil layers with
higher VOC concentrations in layers of lower hydraulic conductivity. Field and laboratory-scale tests were conducted to characterize the hydraulic properties. Computer modeling was used to evaluate various nutrient delivery systems. A vertical flow system with two horizontal wells and a series of surface infiltration galleries was selected to facilitate nutrient delivery vertically across the low conductivity layers.
Construction and operation of the system required groundwater extraction and infiltration capabilities, a control scheme to allow continuous operation and nutrient injection, and aggressive construction techniques for proper location of the system components. These activities, including numerical modeling, laboratory studies, construction techniques, and operational results are summarized in this paper.