Geologic and Hydrologic Implications of Hazardous Wastes Management Rules on Siting in North Carolina

Abstract

Site evaluation can be involved and expensive if the scientific community must predict the ultimate fate of disposed wastes. In selecting a site we accept the basic proposition that the suitability of the site depends on the degree to which it and the surrounding natural system prevents release of wastes to the human environment while they are still toxic. Furthermore, we must accept that the basic scientific difficulties in determining the suitability of a waste storage site or assessing effects of release of waste to the geologic environment are the understanding, measuring, and quantifying of the on-site natural phenomena. Prediction of the effects of sorption, mechanical dispersion, ionic diffusion, and osmosis on waste species concentration in time demands an accurate model of the groundwater flow system and mathematical simulation of solute transport and concomitant chemical changes. The need to know the chemistry of the host rocks and their contained pore fluid, chemistry of leachate, redox potential, and moisture content in the zone of aeration, for example, dictates selection of the least hydrologically and geologically complex site possible. Ideally, this means storage in or above flat-lying, homogeneous, non-fractured siltstone, clay, and/or silty sandstone well above the water table. Unfortunately, this ideal is met almost nowhere in North Carolina. Federal and State regulations recently promulgated under the Resource Conservation and Recovery Act enforce use of presently accepted safe disposal practices and monitoring techniques. The financial impact of these regulations on waste generators and the ultimate success of environmental protection depend much on the degree to which the regulations realistically address geohydrologic complexities.