Infiltration of Municipal Effluent Into Deep Dolomite Wells Located Near the Upper Fox River and its Implications
Mentor 1
Timothy Grundl
Location
Union Wisconsin Room
Start Date
28-4-2017 1:30 PM
End Date
28-4-2017 4:00 PM
Description
The upper Fox River in Waukesha County, WI receives a large amount of effluent, which is being discharged from three municipal wastewater treatment plants located on the river. Previous studies have shown that effluent is infiltrating into shallow sand/gravel wells located directly adjacent to the Fox River. This deduction was made by an observed increase over time in Na and Cl. This observation paired with an observed high B/Cl ratio distinguishes the effluent from road salt, the other primary source of excess Na and Cl in urban areas. This study explored the infiltration of municipal effluent into two other wells located near the Fox River that draw water from a deeper dolomite aquifer. The methods utilized in this experiment include analyzing the temporal changes in major ion content via AA, IC and ICPMS techniques. The mineral dissolution/precipitation and other geochemical reactions were also assessed. The numeric model PHREEQC developed by the U.S. Geological Survey was used to analyze the geochemical reactions within the system. Our findings indicate that the two deep dolomite wells display Na and Cl levels that rise to 2 and 3 times greater than background levels within the deep dolomite aquifer, respectively. Background conditions in the dolomite aquifer were established by examining a third well distal from the river that pumps pristine aquifer water. Furthermore, the B/Cl ratio of observed in these wells indicates that treated effluent is in fact entering the system, as opposed to road salt infiltration. The background well demonstrates neither of these trends. This study establishes that wastewater treatment effluent directly affects the water quality of those municipal wells in the Waukesha area that are located in close proximity to the Fox River. Implications for the transport of other, potentially dangerous compounds into shallow riparian wells in SE Wisconsin will also be discussed.
Infiltration of Municipal Effluent Into Deep Dolomite Wells Located Near the Upper Fox River and its Implications
Union Wisconsin Room
The upper Fox River in Waukesha County, WI receives a large amount of effluent, which is being discharged from three municipal wastewater treatment plants located on the river. Previous studies have shown that effluent is infiltrating into shallow sand/gravel wells located directly adjacent to the Fox River. This deduction was made by an observed increase over time in Na and Cl. This observation paired with an observed high B/Cl ratio distinguishes the effluent from road salt, the other primary source of excess Na and Cl in urban areas. This study explored the infiltration of municipal effluent into two other wells located near the Fox River that draw water from a deeper dolomite aquifer. The methods utilized in this experiment include analyzing the temporal changes in major ion content via AA, IC and ICPMS techniques. The mineral dissolution/precipitation and other geochemical reactions were also assessed. The numeric model PHREEQC developed by the U.S. Geological Survey was used to analyze the geochemical reactions within the system. Our findings indicate that the two deep dolomite wells display Na and Cl levels that rise to 2 and 3 times greater than background levels within the deep dolomite aquifer, respectively. Background conditions in the dolomite aquifer were established by examining a third well distal from the river that pumps pristine aquifer water. Furthermore, the B/Cl ratio of observed in these wells indicates that treated effluent is in fact entering the system, as opposed to road salt infiltration. The background well demonstrates neither of these trends. This study establishes that wastewater treatment effluent directly affects the water quality of those municipal wells in the Waukesha area that are located in close proximity to the Fox River. Implications for the transport of other, potentially dangerous compounds into shallow riparian wells in SE Wisconsin will also be discussed.
