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Micropiles are the most effective deep foundation system in difficult karst geology. In Subsurface Building's solution area, karst is found in the hills of Virginia https://milkyway.cs.rpi.edu/milkyway/show_user.php?userid=5424209 as well as eastern Tennessee. Because karst consists of layers of hard rock and soft soil or gaps, micropiles can be cased through the soft areas to proficient rock.