Test Hole Drilling
ENWRA drilled approximately 40 test holes total across the three pilot study sites in cooperative agreement with CSD between 2006 and 2009. The test holes provide high-quality geologic data and are required in order to make a direct association between HEM survey results and subsurface geology. Downhole geophysical tools are used to log both electrical resistivity and gamma-ray emissions of the geologic materials encountered in the test holes. Test hole drilling continues today in cooperation with ENWRA NRDs to both ground truth AEM survey areas and provide additional borehole constraint on future AEM data processing and interpretation. Click here for a link to CSD's Statewide Test-hole Database and here for more information on the CSD Geological Sample Repository.
Many cross sections were produced by the CSD over the years across portions of eastern Nebraska using the test holes to characterize the regional geology of unconsolidated Quaternary deposits and the bedrock units that lie directly beneath them. These CSD test holes were drilled specifically to investigate subsurface geology and therefore represent the highest quality data available. An archive of CSD drafted cross section locations in eastern Nebraska (includes unpublished) is available in the "Xsectionscans" folder of the ENWRA Archive online.