Current

Fundamental to proper sampling of well water to assess groundwater contamination is an understanding that the composition of water collected from a well is frequently a function of the extent to which the well was pumped (or bailed) prior to sampling, the length of time since water was last withdrawn from the well, and—in some instances—the method of sampling. This is a result of several factors. The ground water of an area fre-quently occurs in multiple strata or aquifers that con-Investigators should never assume that commonly used sampling and analytical methods are applicable to all situations. tribute ground water to a well at different rates depending on the head, the permeability of the aquifer material, and other variables. Further, it is rare that the chemica