GROUNDWATER SAMPLING METHODS USING GLASS WOOL FILTRATION TO TRACE HUMAN ENTERIC VIRUSES IN MADISON, WISCONSIN

Human enteric viruses have been detected in the Madison, Wisconsin deep municipal well system. Earlier projects by the Wisconsin Geological and Natural History Survey (WGNHS) have used glass wool filters to sample groundwater for these viruses directly from the deep municipal wells. Polymerase chain reaction (PCR) analysis techniques provided laboratory identification and quantification of the viruses. The WGNHS work indicated the sanitary sewer system was the most probable source of these viruses.

Current work involves using viruses as a groundwater tracer to confirm that the sanitary sewer is the source of the viruses and to constrain pathways by which effluent constituents travel from the sanitary sewer into the deep municipal water supply well. During April 2010, two groundwater monitoring wells were installed next to a municipal well and all three wells were sampled using the glass wool filtration technique. Due to the low concentration of viruses, a total of 1,000 liters of groundwater was pumped through each glass wool filter to obtain a sample. Four liter composite samples were collected from the sanitary sewer near the well to characterize the source. A total of six sampling iterations were conducted from May to July 2010. This innovative approach to concurrent virus sampling of sanitary sewers, shallow monitoring wells, and deep municipal wells demonstrated the usefulness of utilizing viruses to characterize urban hydrogeological settings. Although some logistical challenges had to be overcome, glass wool filtration is a low cost method to collect viruses for use as a spatial and temporal groundwater tracer.