Initial Publication Date: March 26, 2008

Videoclips of Sand Tank Models

These videoclips show how contamination introduced just below the water table on the W.R. Grace property would travel to discharge locations for three different scenarios. The first scenario (Videoclip #1) demonstrates how contamination entering the flow system at W.R. Grace would travel if Wells G and H were not pumping. The second scenario (Videoclip #2) shows how contamination from W.R. Grace would travel if Wells G and H were pumping at moderate rates. The final scenario (Videoclip #3) demonstrates how contamination would move through the flow system if Wells G and H were pumping at high rates.

The videoclips are overly simplistic representations of an actual three-dimensional, transient flow in a highly heterogeneous flow system using two-dimensional, steady-state flow in a sand tank as a model. The videoclips should be limited to demonstrating major concepts such as flow to wells, river/aquifer interactions, recharge/discharge relations, and vertical hydraulic gradients. The contaminant is represented by red food dye, which manifests the processes of advection and dispersion. Unlike TCE, the red dye is not attenuated in the sand tank by biochemical and geochemical processes. The various of geologic materials are represented by mixtures of sand, gravel, and silt. Flow within the sand tank is controlled by aquarium pumps.