Thousands of abandoned and inactive mines are located in environmentally sensitive mountain watersheds. Water moving through the waste rock material leads to the generation of acid and subsequent leaching of heavy metals from the rock (Figure 1). The resulting leachate can contaminate both surface and groundwater systems. Funded by the US Bureau of Mines and the US Bureau of Land Management.

A bank of humidity cells containing mining waste rock material (Figure 2) is used at the U of Utah in laboratory-based, accelerated weathering experiments. Experiments conducted using these cells are aimed at determining if and when the material will produce acid rock drainage which can leach out heavy metals and contaminate surface or ground waters.

U of Utah Researcher: Ed Trujillo, Chemical & Fuels Engineering

The chemical evolution of lakes that form in abandoned open pit mines (Figure 3) plays an important role in controlling groundwater quality. A key issue is to understand the residence time of water moving through a pit lake. Long times lead to enhanced geochemical interaction with the wallrock. Chemical stratification controls the variations in redox state that must be incorporated in predictive models of lakewater quality.

The following conclusions were reached after studying the Yerington Pit Mine Lake, Nevada (Figure 4):

U of Utah Researcher: Paul Jewell, Geology & Geophysics