BPC-016 Retaining Wall Designs

The following are five (5) approved retaining wall designs. They may be used in lieu of a retaining wall designed by an engineer or architect. A site evaluation (see form CNI-002) and a building permit is required. Deviations from these plans or surcharge loads from adjacent structures, driveways, parking areas, terraced retaining wall(s), or steep slopes within a 45 degree angle from the bottom of the footing require a complete engineer’s design.

Notes

1. 1' minimum compacted fill soil cap shall be moisture conditioned to near optimum moisture content and compacted in 8" maximum lifts to provide an impermeable barrier to surface water infiltration.
2. Per CBC 1803.3 the ground adjacent to a building foundation must slope away from the building at 5% minimum for at least 10feet, or to approved alternative method for diverting water away. Impervious surface within 10' of the foundation must be sloped 2% minimum.
3. Minimum 12" wide, class 2 aggregate base rock or crushed rock wrapped in an approved non-woven filter membrane. A minimum of 2" must be below the drainage pipe and 6" minimum above the pipe.
4. Minimum 4" schedule 40 perforated pipe, holes placed down, sloped 2$ minimum to an approved outlet location. Cleanouts shall be provided as necessary. All 90° bends shall be made with (2) 45° pieces or additional cleanouts may be required.