14.60.150 Slopes.
Slopes shall be constructed with due regard for drainage, access, maintenance, impacts to adjacent property, and aesthetics. Constructed slopes shall comply with all applicable codes and standards and the following criteria:
(1) Fill slopes shall be constructed no steeper than three horizontal to one vertical. Cut slopes may be constructed at a maximum slope of two horizontal to one vertical upon approval of the Director and recommendation of a geotechnical engineer for those areas lying outside the building envelope. In addition, the following standards shall apply to cut and fill slopes:
(a) Minimize clearing and grading on slopes 15 percent or greater. Clearing and grading on slopes shall meet any applicable critical areas standards set forth in Chapter 18.65 CMC.
(b) Slopes shall comply with the land use code restrictions applicable to slopes 40 percent or greater and to areas of colluvial or landslide deposit on slopes of 15 percent or greater.
(c) Do no clearing, excavation, stockpiling, or filling on the potential slide block of an unstable or potentially unstable slope unless it is demonstrated to the Director’s satisfaction that the activity would not increase the load, drainage, or erosion on the slope.
(d) Do no clearing, excavation, stockpiling, or filling on any unstable or potentially unstable areas (such as landslide deposits) unless it is demonstrated to the Director’s satisfaction that the activity would not increase the risk of damage to adjacent property or natural resources or injury to persons.
(e) Intercept any groundwater or surface water drainage encountered on a cut slope and discharge it at a location approved by the Director. Off-site stormwater (run-on) or groundwater shall be diverted away from slopes and undisturbed areas with interceptor dikes, pipes and/or swales. Off-site stormwater should be managed separately from stormwater generated on the site.
(f) Excavated material shall be placed on the uphill side of trenches, consistent with safety and space considerations.
(g) Check dams shall be placed at regular intervals within constructed channels.
(h) At the top of slopes, collect drainage in adequate pipe slope drains or armored channels to prevent erosion.
(2) Existing slopes shall not be over-steepened beyond the criteria in subsection (1) of this section by placing fill or by constructing a fill wall near the top of the slope.
(3) If building sites are prepared by constructing slopes near the property boundary, the slope shall be constructed in accordance with CMC 14.60.135.
(4) Drainage at the top and toe of any slope shall be appropriately collected and discharged.
(a) The ground surface above a slope shall be graded to direct surface runoff to an appropriate collection point. Water shall not be allowed to discharge over the top of a slope.
(b) Slopes shall not be constructed in a location or manner in which surface runoff and debris are permitted to drain onto an adjacent property.
(c) Slopes shall be designed and protected to minimize erosion.
(d) Terraces at least 10 feet in width shall be sloped away from the face of a slope and shall be established at not more than 25-foot vertical intervals to control surface drainage and debris. Swales or ditches on terraces shall have a maximum gradient of five percent.
(e) The tops and the toes of cut and fill slopes shall be set back from property boundaries as far as necessary as determined by a geotechnical engineer for safety of the adjacent properties and to prevent damage resulting from water runoff or erosion. The tops and toes of cut and fill slopes shall be set back from structures as far as is necessary as determined by a geotechnical engineer for adequacy of foundation support and to prevent damage as a result of water runoff or erosion. (Ord. 04-19 § 2 (Exh. B); Ord. 08-13 § 1 (Exh. A))