The ISGS study of the distribution and character of aquifers and non-aquifers in McHenry County also continued in 2010 and 2011. During this period, ISGS researchers continued work with County officials on development of a 3-D hydrogeologic map to assist the County with water supply management and planning. A generalized version of the 3-D hydrogeologic map was provided to ISWS researchers for their use in a groundwater flow modeling study of the County. In addition, ISGS researchers are working with County officials to identify their needs for decision support tools derived from the 3-D map. To date, the ISGS has drilled, cored and logged 17 controlled boreholes, installing groundwater observation wells in 14 of these boreholes, collected 51 kilometers of shallow seismic reflection profiles and 39 kilometers of high-resolution resistivity profiles to describe the character and distribution of glacial sediments and the location of the bedrock surface. ISGS researchers have also helped County officials and U.S. Army Corps of Engineers staff on the location, collection and logging of 14 borings and construction of 27 groundwater observation wells in a related groundwater well network study, and collaborated with USGS researchers in making several of the ISGS groundwater wells available for inclusion in the USGS real-time network of groundwater levels (http://waterdata.usgs.gov/il/nwis/current/?type=gw). The ISGS is scheduled to complete the 3-D map and a draft report in early 2012.
East-Central Illinois – The Mahomet Aquifer is the major groundwater resource in east and central Illinois, extending from the Indiana state line to the Illinois River. Investigation of the hydrogeology of the Mahomet Aquifer and the aquifers overlying it continued to be a high priority at the ISGS in 2010 and 2011. During this period, ISGS researchers continued a study funded by the Illinois American Water Company, to develop a 3-D geologic map of a portion of the Mahomet Valley and overlying sediments. The study area for this project includes an area roughly centered on Champaign-Urbana and the recently developed Illinois American Water Company well field. ISGS provided controlled drilling for several boreholes during this period and collected several miles of seismic reflection and high-resolution resistivity profiles across portions of the study area. These results were combined with other data to help develop a new understanding of the geologic framework of the sediments overlying the Mahomet Bedrock Valley. A generalized 3-D geologic map from this study was provided to researchers at the ISWS who are using it to assist in groundwater flow modeling of this area. The 3-D geologic mapping and associated results are being compiled in a report to the water company in 2011.
Analytic Element Modeling of Groundwater – In 2010, the ISGS published a report documenting the use of an analytical element groundwater flow model to improve predictions of groundwater recharge, and to improve the understanding of both groundwater-surface water interactions, and variations in the hydrogeologic characteristics (Mehnert 2010). The study showed that an analytical element groundwater flow model of the Blackberry Creek watershed in Kane and Kendall Counties was useful for improving estimates of groundwater recharge and for partitioning the watershed into regions of varying geologic complexity and different patterns in groundwater-surface water interaction. Estimates of these hydrologic parameters can be obtained rapidly through analytic element modeling and can serve as valuable input parameters in numerical modeling efforts of groundwater flow.
Geothermal Heat Pumps – Groundwater source geothermal heat pump systems, also called open-loop systems, are very efficient for space heating and cooling, refrigeration, and industrial process cooling. These systems, if properly designed, can result in increased energy efficiencies compared to closed-loop geothermal systems. Information concerning the local hydrogeologic conditions is necessary for successful implementation of open-loop systems. The ISGS is working with the Illinois Sustainable Technology Center and the ISWS on a pilot project that will evaluate the availability of groundwater
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