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TRANSECT STUDY OF THE INTRINSIC BIOREMEDIATION TEST PLOT: DOVER AFB
Citation:
Ei, T. A., D. J. Barnes, G. M. Klecka, D. E. Ellis, E. J. Lutz, AND M. W. Holmes. TRANSECT STUDY OF THE INTRINSIC BIOREMEDIATION TEST PLOT: DOVER AFB. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-02/022 (NTIS PB2002-106289), 2002.
Description:
The work described in this report is part of a project undertaken by the Bioremediation of Chlorinated Solvents Action Team of the Remediation Technologies Development Forum, a joint U.S. Federal agency-industry collaboration, to study the natural attenuation of chlorinated ethenes in the groundwater in Area 6 of Dover Air Force Base, Delaware USA. The purpose of this part of the study was to determine the mass flux of chlorinated ethenes, calculate apparent first-order decay rates, and compare these result to mass flux and degradation estimates from conventional groundwater monitoring well data. The study evaluated the distribution and mass flux of tetrachloroethene (PCE); trichloroethene (TCE); cis-1,2-dichloroethene (cis-1,2-DCE); vinyl chloride;and 1,2-dichloroethane (DCA) in the unconsolidated, fluvial, Columbia Aquifer by collecting samples and determining hydraulic conductivity at 103 discrete points along three transects across the plume. Comparison of the results support the hypothesis that detailed plume analysis by collecting point data is not necessary to demonstrate natural attenuation at a site in which the vertical and lateral morphology of a plume is defined by monitoring well data. The transect study provided no significant information that had not previously been determined from exisiting monitoring well data to justify the estimated study cost. The mass flux for each compound was generally consistent between the transect and monitoring well data. Further analysis of the transect data indicates that mass flux is sensitive to the hydraulic gradient in areas where large variations in hydraulic conductivities were observed.