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Chapter 72 : Placement of Drinking Water Wells and Their Protection
Source Water Assessment and Protection Programs (SWAPPs) require states to delineate and assess the areas of land that contribute to public water systems using both surface and groundwaters. An integral part of these programs is an analysis of the susceptibilities of these systems to chemical and microbial contamination. There are several methods that can be used to establish placement of drinking water wells to minimize microbial contamination. The six most common delineation methods, listed in order of increasing technical complexity, are as follows: arbitrary-fixed-radius method; calculated-fixed-radius method; simplified variable shape method; analytical method; hydrogeologic mapping; and numerical transport models. An analysis of hydrogeology, an understanding of the contaminants and the factors that control their fate and transport in specific environments, and an analysis of the effectiveness of existing prevention and mitigation measures are essential so that states can apply the assessment results to source water protection. There are several components of the proposed groundwater rule (GWR) that require similar assessments of groundwater vulnerability or sensitivity to microbial contamination to those performed by the SWAPP. There are many different methods that can be used to delineate zones around drinking water wells to protect the water supply from microbial contamination. Finally, many of the wells that are used for drinking water are owned and operated by small communities and individual businesses.