DECONTAMINATION OF A POLLUTED AQUIFER USING AN INTERCEPTION SORPTION TRENCH - DISPERSION-ADVECTION ANALYSIS WITH LINEAR HEREDITARY SORPTION

In many instances, a soil may be demonstrably polluted by a chemical but not pose an immediate threat to the environment. In this case, it may be acceptable to put in place a decontamination strategy that ensures the pollutant will remain within a prescribed region and gradually be sorbed onto a substrate over a period of time. One practical way of implementing such a decontamination strategy is to simply excavate a trench around the polluted area and backfill the trench with a sorbant material. Over time, the contaminant will be transported through the soil and sorbed onto the material contained within the trench. When decontamination of the polluted soil is deemed complete, the sorbant material may be removed from the trench in readiness for ultimate disposal. The engineer responsible for the design of such a decontamination strategy would be interested in such questions as the required thickness of sorbant material within the trench, the influence of the partitioning coefficient of the sorbant material on the trench thickness, the time required for contaminant transport through the sorbant material, and the time at which decontamination of the polluted soil is deemed to be complete. This Paper employs a one dimensional dispersion-advection equation to generate non-dimensional design charts that can assist the design engineer in estimating the performance of the proposed decontamination strategy. The potential application of the design charts is demonstrated by means of illustrative examples.