Slump Repair
by Bill Iseminger

During 1984-85 there were major slumps on the east and west sides of Monks Mound. The east slump was repaired by filling in the large scar left by the descending mass of earth. The west slump stabilized after dropping about 2 feet, but reactivated in 1994-95 and the slippage increased along what is referred to as the Second Terrace, so that now the total drop ranges from 3 to 8 feet, and extends over nearly half the length of the mound. This was already an irregular area of ridges and valleys, which may, in part, be due to ancient slumping. The west slump was also very irregular, and could not be repaired in the same way as the east slump.

In recent years, new technology has been developed and the plan is to install a number of Horizontal drains" along the west side. Perforated pipe will be drilled into place, starting near the base and arcing slightly upward into the mound.

The purpose is to relieve the internal water content of the mound which appears to be the agent which activates and aggravates the slumps. New dirt will also be added to fill in the dropped areas and stabilize the surface, and to deter surface water penetration through the large cracks that have formed.