Due to improperly tied in retrofit water stop, major leaks occurred at the joint where an old tunnel met a new one at this water treatment plant. With the water table high year-round, water gushed out of these joints and had to be sealed off from spraying with tin flashing. We removed the concrete topping slab (3′ thick) and began removing elements of the joint. Once down to the sub-slab we began filling the joint with Kryton water stop plug to immediately stop the flow of water, which was being aided by using 3 different sump pumps. After a few rounds we were able to eliminate all but 1 of the sump pumps and began the installation of Sealboss 1510 injection foam to completely stop the water and allow us the time to begin prepping for a concrete pour using the Kryton KIM additive to the mix design to seal off any further migration of moisture. We then started prep work for installation of EMSEAL Submerseal system. Due to the fact we were trying to stop the water from coming in, the Submerseal system was installed upside down; a challenging application but one that worked flawlessly. After the Submerseal was done we added one final layer of protection by installing Sika Combiflex over the entire joint; soffit to wall to slab to wall. This joint is completely bone dry after gushing water for months. A complex project but a satisfying result.