REL Storm Drain Concrete Installation . Cary out ground preparation, base layers, compaction, and pavement design to suit design loads. . Lay Rel Storm Drain on a bed of compacted sand, cracker dust or road base. A concrete base for vehicle applications is recommended in poor sub soil. . Encase REL Storm Drain in concrete, minimum of 4 inches (100mm). Ensure concrete is consolidated around the channel to eliminate air pockets . Lay concrete to suit design loads .