The ORBEEC alignment required crossing the historic Drumanard property to complete the connection of I-265 between Kentucky and Indiana. The Drumanard property is listed on the National Historic Register and surface disturbance of the property is not allowed. The most viable option to overcome this obstacle required a pair of shallow three lane tunnels each approximately 1700 ft. long for the Kentucky HWY 841 approach to the proposed bridge. In order to determine the feasibility of a tunnel a limited geotechnical boring program was performed. The program included groundwater monitoring, core sampling and a small geophysical mapping program which was completed during the 2004 to 2007 time frame. These data were used for the prefeasibility study and a comprehensive test drift and underground coring program was designed and bid with the information to be used to form the geotechnical basis for a final design. For various reasons the test drift plan was abandoned and in 2011 a series of three horizontal core holes, one in each tunnel crown and one in the pillar was completed by S&ME. This data was incorporated into a comprehensive Geologic Baseline Report (GBR) and Geologic Data Report (GDR) prepared by Golder Associates. The GBR and GDR are used in the tunneling industry to present a baseline of geologic conditions a contractor may expect to encounter on a given project and used for input into planning, designing, and performing the work. Included in the GBR are the hydro-geologic conditions, the physical characteristics of the rock mass, the classification of the rock lithologic units to be excavated and the ground support requirements for initial excavation, the stress within the units, and the instrumentation requirements to monitor the reaction of the rock mass to the excavation process.
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