DESIGN AND CONSTRUCTION OF A SUB-LINER DRAIN SYSTEM FOR THE LUDINGTON PUMPED STORAGE PLANT

摘要

The Ludington Pumped Storage Plant (LPSP) is an 1872 megawatt capacity hydroelectric plant located on the eastern shore of Lake Michigan. The facility was the largest pumped storage plant in the world when it was put into service in 1973. At 842 acres and 27 billion gallons of water, the upper reservoir is still the largest man-made pumped storage reservoir in the United States. Water flow into and out of the upper reservoir is through a massive concrete intake structure. The upper 80 vertical feet of the interior slope of the reservoir is protected by a hydraulic asphaltic concrete liner system (asphalt liner) that contains a gravel drain layer with dike drain pumps for seepage detection and control. Shortly after construction, a bulge developed in the asphalt liner adjacent to the intake structure. The bulge cracked the upper asphalt layer in 1974, activating the dike drain pumps. Investigations of the bulge area found excessive hydrostatic pressures existed beneath the asphalt liner. A well-point dewatering system was installed in 1975 to relieve sub-liner pressures but further deformation of the asphalt liner occurred. The well-point system was also periodically damaged by ice loading. A new drain system, to be constructed below the asphalt liner, was designed to replace the well-point system. Construction was completed in 2009 by around-the-clock operations during a three-week outage.