C. In addition to ground cover, slopes exceeding fifteen (15) feet in height shall be planted with trees at twenty (20) feet O.C. or shrubs at ten (10) feet O.C. or a combination of both at equivalent spacings.
Trees shall be selected from the following list:
Albizia julibrissin, Mimosa
Chilopsis linearis, Desert Willow
Koelreuteria paniculata, Golden Rain Tree
Pistacia chinensis, Chinese Pistacio
Cedrus deodora, California Christmas Tree
Pinus eldarica, Mondell Pine
Pinus pinea, Italian Stone Pine
Requests for substitutions shall be submitted in writing and shall be based upon climatic, ecological and site conditions. Substitutions shall be demonstrated to have rooting characteristics necessary for erosion control.
Planting need not be provided for cut slopes rocky in character and not subject to damage by erosion and slopes protected against erosion damage by other methods when such methods have been specifically recommended by a soils engineer, engineering geologist or equivalent authority and found to offer erosion protection equal to that provided by the planting specified in this section.
Slopes required to be planted shall also be irrigated with a permanent, electrically controlled automatic system designed to cover all portions of the slopes.
The irrigation system shall be installed with an approved backflow device.
All piping shall be installed underground. Trenches shall be compacted to the adjacent grade.
Impact type irrigation heads shall not be allowed. Stream rotors are required for large areas.
A minimum of head to head coverage is required.