1.1 ,This guide provides procedures for the installation of DWV piping in buildings that are built where soil conditions require the use of pier or piling supported grade beam construction or in filled ground where the soil compaction is less than 95 ,%. These procedures are intended to ensure that the DWV piping suspended from the on grade concrete slabs is not damaged or destroyed by movement of the soil or fill under the slab after the building is completed and occupied.