Design Standards Summary
The design standards for grading are presented in detail in Volume III of the County Design and Improvement Standards Manual. Provided below in summary form are the key standards common to most grading projects.
(Excerpts from Volume III of the County Design and Improvement Standards Manual)
Excavation – Cut Slope Standards
Slope steepness: No excavation shall be made with a cut face steeper in slope than two horizontal to one vertical (2:1), exclusive of required terraces and roundings.
Terrace requirements: For cut slopes up to 60 feet in height, terraces at least 8 feet (2.4 meters) in width shall be established at not more than 30-foot (9.1 meters) vertical intervals on all cut slopes to control surface drainage and debris except that where only one terrace is required, it shall be at midheight.
Terrace rounding: Cut slopes shall be rounded into the existing terrain to produce a contoured transition from cut face to natural ground.
Fill Construction Standards
Ground preparation for fill placement: The natural ground surface shall be prepared to receive fill by the removal of all unsuitable material such as vegetation, top soil, landslide deposits or other unstable earth material and existing fill not installed in conformance with this ordinance.
Placement of fill: Fills shall be constructed in layers. The loose thickness of each layer of fill material before compaction shall not exceed eight inches.
Slope steepness: No fill shall be constructed with a face steeper in slope than two horizontal to one vertical (2:1), exclusive of required terraces.
Terrace requirements: For fill slopes up to 60 feet in height, terraces at least 8 feet (2.4 meters) in width shall be established at not more than 30-foot (9.1 meters) vertical intervals on all fill slopes to control surface drainage and debris except that where only one terrace is required, it shall be at mid-height. Terraces shall slope a minimum of 5 percent gradient toward the hillside and be accessible for maintenance.
Drainage
General requirements: Drainage structures and facilities shall be designed and constructed in accordance with the standards included in this Volume, other applicable sections of the Design and Improvement Standards Manual(PDF, 6MB), the County Drainage Manual(PDF, 10MB), the California Building Code, Natural Resource Conservation Service guidelines, and other documents as determined by the Director.
Disposal requirements: All drainage facilities shall be designed to convey surface runoff and subsurface waters to the nearest available street, storm drain, watercourse, detention basin or other disposal point adequate to accommodate the estimated flow from the proposed development as determined by the Director.