SAND AND GRAVEL RESOURCE OF MCHENRY COUNTY, ILLINOIS: DISTRIBUTION, THICKNESS AND LAND USE

Parts of McHenry County in northeastern Illinois are underlain by extensive deposits of sand and gravel, which makes it a leading county in Illinois for sand and gravel production. An up-to-date aggregate resource map is needed to identify potential resources before it is preempted by urbanization.We use borehole data and water well records to prepare a resource map to show the thickness, burial depth, distribution and availability of sand and gravel in McHenry County. The thickness data of the sand and gravel were exported from the three-dimensional geologic framework model of McHenry County, by combining the individual thickness data of multiple, interconnected sand and gravel deposits. Depth of burial was extracted from individual deep drill hole data maintained by the Illinois State Geological Survey. In addition to the geological aspect of the sand and gravel deposits, we also assessed whether these deposits were available for mining under current land use practices. For example, the sand and gravel resources are not minable in the residential and other developed areas. This map shows that a significant loss of minable resources has occurred in McHenry County due to land use, especially in the eastern half of the county, which is heavily urbanized and where aggregate resources are most needed.This map can help constituents in the sand and gravel industry find needed construction resources with implications for aggregate quality, transportation, and economic feasibility. As the Chicago metropolitan area population continues to grow, the distribution of economically mineable sand and gravel deposits in McHenry County and nearby counties will become increasingly important for land use, environmental planning and groundwater resource decisions.