The exterior brick wall of the gymnasium at PS 192, which is supported on a retaining wall, had tilted outward and separated from the adjacent columns. YU & Associates, Inc. (YU) was called in to investigate and determine if the defective condition of the gymnasium wall was the result of settlement or movement of the supporting retaining wall.
YU developed and supervised a field investigation program involving excavation of test pits at the toe of the retaining wall to determine the foundation bearing condition. Holes were also cored through the retaining wall to determine if hydrostatic pressure existed behind the wall and to measure the wall thickness. In addition, a dye test was performed for the roof drain pipe to determine if any of them discharged or leaked into the area behind the retaining wall.
Our investigation concluded that the supporting retaining wall was geotechnical stable, and that the overlying brick wall movement was unrelated to any settlement of the retaining wall. It was believed that persistent roof leakage had softened the mortar of the brick wall and caused its outward deflection. Recommendations were then given to monitor the brick wall, replace the roofing material, check the structural integrity of the retaining wall, and develop a permanent structural remedial design.