The Mingtan Power Plant has a 58-meter-high concrete gravity dam. Verticalcontraction joint leakage problems occurred, and with the water level at itshighest, the leakage rate was 2,100L/min.The main challenge of the project was how to achieve water stoppage effect, without blocking the original drainage pipes buried in the contraction joints.The solution to the water leakageproblem was implemented utilizing a variety of grouting methods, including polyurethane resin injection, high pressure LW grouting and ducted cement bentonite grouting.Using the combined characteristics of the different grouts,a very significant result of 96% reduction in water leakage was achieved.This project had been finished in December 2000. The total contract amount was about 5 million NT dollars.