The design called for the new playing field to be elevated five to six feet above the grade of the old parking lot. The additional fill necessary to accommodate this design would have increased the load on the weak native soils an estimated 700 pounds per square foot. The additional load would cause significant settlement, requiring lengthy and expensive soil surcharging until the settlement subsided and construction could resume. Most of the proposed solutions for this situation were costly and would have a negative impact on the construction schedule. The initial plan to reduce the load on the native soils included 4 feet of lightweight aggregate as fill, bearing a density of approximately 55 pcf after compaction.
Alternatively, the specialty contractor recommended the use of AQUAERiX pervious cellular lightweight concrete (PCLWC) as a subbase. The PCLWC has an average density of 29 pcf, attaining strengths of 80 psi. In order for the value-engineered option to be accepted by the owner, the AQUAERiX PCLWC was required to be as free-draining as the originally specified lightweight aggregate resulting from the lack of an infield drainage system that would support using a non-pervious fill material.