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USER FRIENDLY MODELS FOR EVALUATING HYDROGEOLOGIC BARRIERS TO VIRUSES
Citation:
Faulkner*, B P. USER FRIENDLY MODELS FOR EVALUATING HYDROGEOLOGIC BARRIERS TO VIRUSES. Presented at Regional ORD Training Workshop on Emerging Issues Associated with Aquatic Environmental Pathogens, Ft. Meade, MD, 09/06/2001.
Description:
Impending regulations in U.S. EPA's forthcoming Ground Water Rule (Federal Register, 2000) will require public water systems (PWS) to more closely monitor their groundwater systems for contamination by pathogens. As part of this process, State resource managers will assess the sensitivity of ground-water systems supplying drinking water. If it can be shown that the risk is low due to the presence of a hydrogeologic barrier, the State can exempt the PWS from a high risk status. A hydrogeologic barrier is defined as a subsurface region through which viruses must pass from a source in order to reach PWS wells that provides at least 4-log (99.99%) attenuation of active pathogenic viruses. The proposed rule indicates attenuation factors are "physical, biological, and chemical" acting "singularly or in combination." In instances where the groundwater system in question is connected to potential virus sources by karst, fractured rock, or gravel, the system will be classified as high risk. In other cases the assessment process is likely to utilize mathematical modeling. Therefore, EPA's Office of Water has requested that quantitative models, simple to use and understand, be developed to assist State managers in hydrogeologic sensitivity assessments. This talk presents the development of a proposed model to evaluate attenuation as viruses are carried with percolating water in an unsaturated, naturally existing soil layer. The model itself will ultimately be a applet which can be run on any computer connected to the World Wide Web.