The existing membrane had failed and was scheduled to be replaced. The existing over burden was removed to expose the existing membrane. The existing liquid membrane was removed from the concrete substrate. The concrete substrate was reviewed for existing defects such as divots, voids and delamination of the reinforcing steel rebar. Once the substrate defects were repaired, the low point was located by plugging the single drain and flooding the membrane. A new mechanical drain was installed and tied into the existing storm system. The prepared substrate was covered with a new 2 ply SBS membrane system. Over the completed SBS membrane drainage board was installed, followed by 2” Type IV extruded insulation (loose laid) and then a filter fabric was installed on top of the insulation. The final step was to install 2” of drain rock on top of the filter fabric.