DEVELOPMENT AND TESTING OF A CONTAMINATION POTENTIAL MAPPING SYSTEM FOR A PORTION OF THE GENERAL SEPARATIONS AREA, SAVANNA RIVER SITE, SOUTH-CAROLINA

A methodology was developed to evaluate and map the contamination pote ntial or aquifer sensitivity of the upper groundwater flow system of a portion of the General Separations Area (GSA) at the Department of En ergy's Savannah River Site (SRS) in South Carolina. A Geographic Infor mation System (GIS) was used to integrate diverse subsurdata, face geo logic data, soils data, and hydrology utilizing a stack unit mapping a pproach to construct mapping layers. This is the first time that such an approach has been used to delineate the hydrogeology of a coastal p lain environment. Unit surface elevation maps were constructed for the tops of six Tertiary units derived from over 200 boring logs. Thickne ss or isopach maps were created for five hydrogeologic units by differ encing top and basal surface elevations. The geologic stack-unit map w as created by stacking the five isopach maps and adding codes for each stack-unit polygon. Stacked-units were rated according to their hydro geologic properties and ranked using a logarithmic approach (utility t heory) to establish a contamination potential index. Colors were assig ned to help display relative importance of stacked-units in preventing or promoting; transport of contaminants. The sensitivity assessment i ncluded the effects of surface soils on contaminants which are particu larly important for evaluating potential effects from surface spills. Hydrogeologic/hydrologic factors did not exhibit sufficient spatial va riation to warrant incorporation into contamination potentail assessme nt. Development of this contamination potential mapping system provide s a useful tool for site planners, environmental scientists, and regul atory agencies.