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USING TRACERS TO DESCRIBE NAPL HETEROGENEITY
Citation:
Espinoza, F., A L. Wood*, M. C. Brooks, AND C G. Enfield*. USING TRACERS TO DESCRIBE NAPL HETEROGENEITY. Presented at American Geophysical Union (AGU) Meeting, San Francisco, CA, December 13 - 17, 2004.
Impact/Purpose:
To inform the public.
Description:
Tracers are frequently used to estimate both the average travel time for water flow through the tracer swept volume and NAPL saturation. The same data can be used to develop a statistical distribution describing the hydraulic conductivity in the sept volume and a possible distribution of the NAPL in the heterogeneous flow field. To determine the statistical distributions we use a simple genetic algorithm to evaluate the parameters of an advective dominated stochastic Lagrangian model. Eight possible NAPL architectures are considered in an attempt to describe the NAPL heterogeneity. The method is appropriate when transverse dispersion is small but would not be appropriate where the formation is dominated by interbeded sands and clays. The approach is illustrated using tracer data from two different sites. Once the model parameters are determined the effects of the site specific NAPL heterogeneity on pump-and-treat remediation can be observed. Changed in contaminant mass flux and fraction of contaminant mass removal are projected as a function of the number of pore volumes extracted by the pump-and-treat system.