Abstract

Minerals in the central Wasatch Range, Utah have been mined by either subsurface or surface (strip) methods, both of which can disrupt the natural flow of groundwater and cause acid mine drainage (AMD). Mine drainage waters were collected from fourteen mine-adit openings, and at these sites, δ¹³C and δ³⁴S compositions were used to help identify the controlling factors of AMD. In addition, electrical methods were used to map the existence and approximate level of contamination by mapping ground resistivity. When combined with some knowledge of the subsurface hydrogeology and geochemistry, the resistivity map can give a good indication of the structure and extent of the sources and flow of the groundwater contamination. Lower resistivity values typically correlate with areas of AMD, while areas of relatively higher resistivities indicate AMD-free water.

In this study, resistivity sounding data were collected at 49 locations around a mine-adit opening located in Little Cottonwood Canyon, near Salt Lake City, Utah, and at 18 locations near a mine-adit opening located in American Fork Canyon (Pacific Mine), approximately 19 km (12 miles) north of Provo, Utah. At the Little Cottonwood Canyon site, the lower resistivities outline the flow of groundwater contamination caused by AMD, and correlate with higher contamination and acidity found in nearby wells. The associated adverse effects on the groundwater, soil, flora, and fauna systems become very important considerations for future building and development in this area. In contrast, at the American Fork Canyon site, higher resistivities indicate that the groundwater is free of AMD.