|GOTKOWITZ, MADELINE - Wisconsin Geological And Natural History Survey|
|BRADBURY, KENNETH - Wisconsin Geological And Natural History Survey|
|ZHU, JUN - University Of Wisconsin|
Submitted to: Environmental Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/18/2016
Publication Date: 7/19/2016
Publication URL: http://handle.nal.usda.gov/10113/5394249
Citation: Gotkowitz, M.B., Bradbury, K.R., Borchardt, M.A., Zhu, J., Spencer, S.K. 2016. Effects of climate and sewer condition on virus transport to groundwater. Environmental Science and Technology. 50:8497-8504. 2016.
Interpretive Summary: In communities that rely on groundwater for their drinking water supplies, the wells are often located within the community. While having wells in close proximity is cost effective, one disadvantage is that the wells are then near the community’s sanitary sewers, which can possibly leak and contaminate the supply wells. We related characteristics of sanitary sewers near 22 wells in Madison, Wisconsin to how often these wells were contaminated with human viruses that originate from sewer wastewater. We found that the older the sewer pipes near a well, the more likely the well was contaminated with viruses. The density of the sewer network was not related to well contamination. The relationship with sewer age was only evident during time periods when there was precipitation that could move the viruses downward through the ground. During dry periods, no relationships could be found between sewer characteristics and well contamination. Our findings highlight the importance of precipitation as a factor in groundwater contamination by pathogens in wastewater and likely other fecal sources such as manure. Moreover, our findings will help guide decisions on when sanitary sewers should be replaced to protect groundwater quality.
Technical Abstract: Pathogen contamination from leaky sanitary sewers poses a threat to groundwater quality in urban areas, yet the spatial and temporal dimensions of this contamination are not well understood. In this study, 16 monitoring wells and six municipal wells were repeatedly sampled for human enteric viruses. Viruses were detected infrequently, in 17 of 455 samples, compared to previous sampling at these wells. Thirteen of the 22 wells sampled were virus-positive at least once. While the highest virus concentrations occurred in shallower wells, shallow and deep wells were virus-positive at similar rates. Virus presence in groundwater was temporally coincident, with 16 of 17 virus-positive samples collected in a six-month period. Virus detections were associated with precipitation events and occurred infrequently during a prolonged drought. The study purposely included sites with sewers of differing age and material. The rates of virus detections in groundwater were similar at all study sites during this study, but showed a relationship to sewer age during an earlier study conducted during an extended period of high precipitation. The finding that pathogen transport to groundwater increases during periods of precipitation may explain an association between precipitation and waterborne illness documented in communities supplied with non-disinfected groundwater.