ABSTRACT
As mentioned in the Literature (Rail, 1989), groundwater constitutes a significant source of water in most areas of the United States and may be defined as subsurface water that occurs beneath the water table in soil and geologic forms that are fully saturated (Freeze and Cherry, 1979; Pye et al., 1983; U.S. EPA, 1990; Zoller, 1994; Adriano, 1994; Bois and Luther, 1996; Boulding, 1995; Deutsch, 1998; Palmer, 1996). Groundwater [URL Ref. No. 7-8] is also a integral part of the hydrologic cycle [URL Ref. No. 162], an impor tant natural resource, and any evaluation of contamination problems should recognize this (Van der Leeden, 1971; Bois, 1994; Bois and Luther, 1996; Bois, 1998). The hydrologic cycle [URL Ref. No. 51-52], according to the U.S. Geological Survey (1978), is a natural machine, a constantly running distillation and pumping system, that is supplied by energy from the sun. Gravity keeps water moving from the earth to the atmosphere via the vehicles of evaporation and transpiration. Water moves from the atmosphere to the earth in the form of condensation and precipitation. It then moves between points on the earth in streamflow and groundwater movement systems. This closed ecosystem [URL Ref. No. 182] does not lose water or gain it, but the amount of water available to eventual users fluctuates because of variations that can occur at the source. The U.S. Geological Survey (1978) summarizes aspects of the hydrological cycle [URL Ref. No. 51-52] as follows:
• Every second, millions of molecules heated by the sun evaporate and supply water for the hydrologic cycle.
