Water was leaking out of this lake because it was flowing under the spillway instead of over it. Polyurethane grout injection was used to remedy the situation. Holes were drilled on the face deep enough to reach the backside of the spillway. Mechanical packers were then placed in the hole. The installed packers are now an injection port to hook up to the grout pump, which pumps the polyurethane to the back side of the spillway. The grout used was Hyperflex, a moisture activated polyurethane. Once in contact with the water, it foams to fill the voids and seal the leak paths. Hyperflex is NSF/ANSI/CAN 61 approved for contact with potable water and is manufactured by SealGuard, Inc. The grouting was performed by Sub-Technical, Inc.