Abstract
In February 2008, the ISGS was asked to prepare a report on the state of karst terrane in northeastern Jo Daviess County by the Jo Daviess County Board. This action was precipitated by an application for the siting of two Mega-dairies in the county by a California firm. The company proposed constructing two large dairies that would house 6,850 animals at each site. The next month the ISGS was asked to update the report for the Illinois Attorney General’s Office. Subsequent to those reports, the dairies have proven to be highly controversial and local landowners are concerned about potential contamination of their groundwater supplies. Jo Daviess County lies within the Driftless Area of northwestern Illinois, so-called because of the lack of glacial drift overlying bedrock in the area. Bedrock underlying the proposed dairy sites consists of Middle and Upper Ordovician carbonate-dominated Galena-Platteville Group and the shale-dominated Maquoketa Group. Carbonate rocks of the Galena Group overlie those of the Platteville Group and are composed of fine-grained limestone and dolomite. Thin remnants of Maquoketa shale overlie these carbonate rocks in many places. Most of Jo Davies County has been characterized as karst based on the dominance of creviced carbonate bedrock (Weibel and Panno, 1997). This creviced carbonate bedrock is an important aquifer for municipal and private wells throughout the county. The dairy sites are underlain by this carbonate bedrock that is overlain by 5 to 20 feet of unconsolidated materials (some of which includes Maquoketa shale). Aerial photographs of the sites taken in 1947 revealed sinkholes in an undeveloped section of land immediately adjacent to one of the proposed sites. Subsequent agricultural activities on this land have totally obscured those features. Further, contamination of the aquifer (probably from road salt, private septic systems, and N-fertilizers) at depths of hundreds of feet suggest that the karst aquifer is highly susceptible to surface-borne pollutants, contains a well-connected fracture system, and has rapid groundwater travel times. Given that the planned waste lagoons containing over 100 million gallons of waste will be sitting above the karst aquifer, the potential for groundwater contamination from spills and/or seeps of animal waste would be very high. The position of the California firm is that the area is not karst, based on roughly 5 boreholes drilled into bedrock at each site. Because the boreholes did not intersect any karst features, they maintain that there are no karst features beneath the dairy sites. They made this statement in spite of the fact that bedrock exposures literally surrounding the sites contain abundant solution-enlarged crevices. Engineers and a geologist working for the California firm contend that the crevices are due to blast damage from quarry operations, and backhoe marks, and that the sinkholes are actually hog wallows, tile blowouts, or unmapped “dogholes” from early mining efforts. Based on their site characterization efforts, the IL Department of Agriculture has granted permission for construction of a dairy on one of the sites; a ruling on the other site is pending. Local residents are attempting to stop construction through litigation; hearings are scheduled through October 20 of this year. This presentation will chronicle the efforts to resolve this issue and describe the role played by the Illinois State Geological Survey in the field and in the courtroom.
Original language | English (US) |
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State | Published - 2008 |
Event | Illinois Groundwater Association 2008 Fall Meeting - Utica, United States Duration: Oct 22 2008 → Oct 22 2008 |
Conference
Conference | Illinois Groundwater Association 2008 Fall Meeting |
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Country/Territory | United States |
City | Utica |
Period | 10/22/08 → 10/22/08 |
Keywords
- ISGS