Step 3: Spill Moves Through Aquifer Towards Wells
The contaminant continues to spread. As the plume expands, parts of the plume are drawn towards the wells by the suction force created from pumping the well
The rate at which a contaminant will move through the aquifer will vary not only with the characteristics of the aquifer but also with the characteristics of the contaminant. Some contaminants are heavier than water and will continue to sink until reaching an impervious surface. These types of substances are often called “sinkers” or DNAPL’s (dense non-aqueous phase liquids). Many chlorinated solvents such as perchloroethylene (“per-kloro-ethyl-een”), a cleaning solvent, are sinkers. Other contaminants are lighter than water and “float” near the water table. These types of substances are called “floaters” or LNAPL’s (light non-aqueous phase liquids). Petroleum is an example of a floater.
It is important to remember that although most pollutants tend to float or sink, all can dissolve in water to a certain level, further increasing the severity of contamination and difficulties involved in remediating the contamination.