This elevator shaft was leaking groundwater in between the floor and the first course of concrete filled block walls. Although this shaft has a drainage system, it needed to be dry to pass the final building inspection. To stop the unwanted inflow, polyurethane grout was injected to seal the leak paths. The grout used was Hyperflex and was injected by a pump and mechanical packers. Hyperflex is a single component, pre catalyzed, moisture activated polyurethane that is NSF/ANSI/CAN 61 approved for contact with potable water. Hyperflex is manufactured by SealGuard, and the grouting was performed by Sub-Technical, Inc.