Assessment of virus presence and potential virus pathways in deep municipal wells

Among the many waterborne pathogens of humans, enteric viruses have the greatest potential to move deeply through the subsurface environment, penetrate aquitards, and reach confined aquifers. Previous research revealed the presence of viruses in water from two of three deep bedrock wells sampled in Madison, WI. Virus presence in these wells was particularly surprising because the wells were cased through a regional aquitard thought to provide protection for the wells. This present study is a follow-up to the previous work, and is intended to determine the potential sources of the viruses and their pathways to the wells.

Objectives

The objectives of this project are (1) to obtain a time series of virus, isotopic, and geochemical data from several municipal wells completed in a deep bedrock aquifer, (2) to use these data sets to evaluate virus presence and, if present, the potential sources of the viruses and pathways to the wells, and (3) to evaluate the possibility that virus transport occurs through the well casing, grout or annular space. This one-year project was entirely conducted in Madison WI, using wells owned and operated by the Madison Water Utility.