AN INTEGRATION OF GEOPHYSICAL METHODS AND GEOCHEMICAL ANALYSIS TO MAPACID-MINE DRAINAGE - A CASE-STUDY

Discharge waters from 88 sites in the central Wasatch Range, Utah have been evaluated over a 1060 km(2) study area. Generally, these groundw ater systems have Ca2+ and HCO3- as principal ions; many samples have Mg2+ and SO42- as abundant secondary ions (Loucks, 1993). In the study area, mine drainage waters were collected from fourteen mine-adit ope nings, and at these sites, delta(13)C and delta(34)S compositions were used to identify the controlling factors of acid mine drainage (AMD). Minerals in the area were mined by either subsurface or surface (stri p) methods, both of which can disrupt the natural flow of groundwater and cause pollution. Electrical and electromagnetic methods can be use d to map the existence and approximate level of contamination by mappi ng ground resistivity (or conductivity). When combined with some knowl edge of the subsurface hydrogeology, the resistivity map can give a go od indication of the structure and extent of the sources and flow of t he groundwater contamination. The lower resistivity values correlate w ith the contamination plume and the areas of AMD. In this study, resis tivity sounding data were collected at 79 locations around a mine-adit opening located in Little Cottonwood canyon, near Sandy, Utah. The lo wer resistivities outline the flow of groundwater contamination caused by AMD, and correlate with higher contamination and acidity found in nearby wells.