COMPREHENSIVE ENVIRONMENTAL BASELINE STUDIES: THE FIRST STEP IN REASONABLE AND RESPONSIBLE MINING REGULATIONS

Sustainable mining requires that resource extraction be done in an environmentally responsible fashion at a reasonable economic cost. Successful permitting of metallic or non-metallic mining operations necessitates adherence to all relevant environmental regulations. It is vital that these regulations are developed with a comprehensive understanding of current environmental conditions. The rapid expansion of silica sand mining in the upper Midwest provides an illustrative example of the need for recognizing preexisting natural conditions prior to instituting environmental regulations. The Wisconsin Department of Natural Resources recently proposed regulations that require monitoring of trace metals (n=25) in wastewater discharge, but developed these regulations without considering existing environmental conditions. For example, current regulation requires speciation of trivalent and hexavalent chromium, even though the background level of chromium in surface water and groundwater in western Wisconsin is <1 ppb, two orders of magnitude lower than the US EPA drinking water standard (100 ppb).

A source to sink study was designed to provide a comprehensive assessment of surface water and groundwater chemistry across western Wisconsin. The study area encompasses the majority of silica sand operations and targets surface water form 2^nd, 3^rd and 4^th order streams (n=~80), groundwater from municipal wells (n=~15), geochemical analysis of the regional stratigraphy (n=~100) and analysis of mine storm water, process water and waste material in order to determine the range of metal concentrations in each setting. Initial results show trace metal concentrations are orders of magnitude below EPA drinking water standards in surface water and groundwater. Average values include: As <1 ppb (EPA= 10 ppb), Cr <1 ppb (EPA=100 ppb), Pb <5 ppb (EPA=15 ppb). Whole rock geochemistry suggests there is limited mobility from the geologic material to the water. Ongoing sequential extraction analysis will characterize trace metal mobility in both natural and disturbed settings. These studies are fundamental in providing industry and legislators with data that can be used to create reasonable and responsible regulation that will safeguard natural resources and foster economic growth throughout the region.