Portable Secondary Containment For Drums, Tanks, Equipment And Vehicles. Stake Wall Model Containment Berms feature a unique design that allows the sidewalls to collapse in either direction and spring back automatically to their upright position! Roll drums over the sidewalls, drive trucks through them, and the sidewalls always return to vertical without assistance. Does not rely on inflation, hinged straps or cumbersome frames to keep sidewalls up. No set-up required - unfold and the sidewalls automatically spring into their vertical position.