Chapter 18.160
PROTECTION STANDARDS FOR NATURAL FEATURES
Sections:
18.160.030 Bluffs and erosion hazard areas.
18.160.040 Ravines and ravine buffers.
18.160.050 Floodplains – Floodways.
18.160.070 Soil erosion and sedimentation control.
18.160.010 Purpose.
All development shall be preceded by the identification of any environmental or natural feature described in MCMC 18.160.020 through 18.160.070 and shall meet the environmental protection standards applicable to each natural resource identified therein. Reference in this chapter to “open space” is intended to mean the term as it is defined in Chapter 18.10 MCMC. [Ord. 508 § 5.04.0, 1982].
18.160.020 Steep slopes.
In areas of steep slopes, the following standards shall apply:
(1) Twelve to less than 16 percent slope: no more than 40 percent of such areas shall be developed and/or regraded or stripped of vegetation.
(2) Sixteen to 25 percent slope: no more than 30 percent of such areas shall be developed and/or regraded or stripped of vegetation, with the exception that no more than 20 percent of such areas may be disturbed in the case of poor soil suitability (i.e., Nonpareil No. 5).
(3) More than 25 percent slope: not more than 15 percent of such areas shall be developed and/or regraded or stripped of vegetation, with the exception that no more than five percent of such areas may be disturbed in the case of very poor soil suitability (i.e., Nonpareil No. 6).
(4) All erodible slopes shall be protected in accordance with the control standards contained in MCMC 18.160.070. [Ord. 508 § 5.04.1, 1982].
18.160.030 Bluffs and erosion hazard areas.
(1) All such areas shall remain as permanent open space. No uses or improvements other than those permitted herein shall be permitted in any erosion hazard area or any area consisting of bluff as defined by this title.
(2) In the erosion hazard area associated with bluffs, any nonstructural recreational use is permitted, including pedestrian accessways.
(3) Erosion hazard areas may be used to provide vehicular access to nonhazard areas. In this event, an environmental assessment (or site investigation report) shall provide the basis for location of such access. Minimum damage to the area shall be the guide in location of the access.
(4) All erodible slopes shall be protected in accordance with the control standards contained in MCMC 18.160.070. [Ord. 508 § 5.04.2, 1982].
18.160.040 Ravines and ravine buffers.
(1) At least 98 percent of all ravines shall remain in permanent open space. At least 80 percent of all ravine buffers shall remain in permanent open space. No uses or improvements other than those permitted herein shall be permitted in any area consisting of ravines or ravine buffers as defined by this title.
(2) Ravines shall not be the site of any land use or development, with the exception that access to other areas may be provided in ravine areas. In this event, an environmental assessment (or site investigation report) shall provide the basis for location of such access. Minimum damage to the area shall be the guide in location of the access. The protected areas of ravine buffers shall be used only for passive recreation.
(3) All erodible slopes shall be protected in accordance with the control standards contained in MCMC 18.160.070. [Ord. 508 § 5.04.3, 1982].
18.160.050 Floodplains – Floodways.
(1) The determination of floodplain boundaries and the standards for flood hazard area protection are contained in the regulations for the special district/flood hazard area. Whenever any land located in a stream channel or body of water is disturbed, a soil erosion or sedimentation control plan shall be submitted in accordance with MCMC 18.160.070.
(2) Located within areas of special flood hazard are areas designated as floodways. In accordance with the natural resources element of the comprehensive plan, the floodway shall be designated as open space, forming a greenway, and is to be incorporated in the recreation/open space system proposal. Rights-of-way or easements, whenever feasible, shall be provided at the time of development on all properties located in the floodway as shown on the open space (greenway) proposal.
(3) Greenways are linear green belts linking residential areas with other open space areas. These greenways may contain bicycle paths, footpaths and bridle paths. Connecting greenways between residences and recreational areas is encouraged. Maintenance is limited to minimum removal and avoidance of hazards, nuisances, or unhealthy conditions. [Ord. 508 § 5.04.4, 1982].
18.160.060 Drainageways.
No more than 50 percent of such areas shall be developed. The remaining 50 percent shall remain as permanent open space. Regrading, stripping of vegetation, or filling is permitted in these areas; provided, that:
(1) The time of concentration of stormwater flows remains unchanged or is lengthened.
(2) Stormwater and ground water storage capacity is unchanged or increased.
(3) Vegetation is replanted.
(4) The resultant new drainageway has less velocity than preexisted or reduces streambank erosion through the provision of erosion control measures. [Ord. 508 § 5.04.5, 1982].
18.160.070 Soil erosion and sedimentation control.
(1) SESC Plan. In order to prevent both soil erosion and sedimentation, a soil erosion and sedimentation control plan shall be required as part of an application for development whenever any land located in a stream, stream channel or body of water is disturbed and whenever a development will involve any clearing, grading, transporting, or other form of disturbing land by the removal of earth, including the mining of minerals, sand, and gravel; provided, that any one of the following descriptions applies to said movement of land:
(a) Excavation, fill, or any combination thereof will exceed 500 cubic yards.
(b) Fill will exceed three feet in vertical depth at its deepest point as measured from the natural ground surface.
(c) Excavation will exceed four feet in vertical depth at its deepest point as measured from the natural ground surface.
(d) Excavation, fill, or any combination thereof will exceed an area of 5,000 square feet.
(e) Plant and/or tree cover is to be removed from an area exceeding 5,000 square feet on any parcel of land.
(Note: Specifically exempted from the requirement of a soil erosion and sedimentation control plan are agricultural uses.)
(2) Definitions for the purpose of this section are:
“Erodible slope” shall mean all land with inclines in excess of four percent.
“Large flat surface area (unpaved)” shall mean an area which is flat or whose slope is less than four percent and which consists of more than 1,000 square feet of exposed soil.
“Sedimentation” shall mean the settling out of the soil particles which are transported by water or wind. Sedimentation occurs when the velocity of water or wind in which soil particles are suspended is slowed to a sufficient degree and for a sufficient period of time to allow the particles to settle out of suspension or when the degree of slope is lessened to achieve the same result.
“Soil erosion” shall mean a removal and/or loss of soil by the action of water, ice, gravity, or wind. Erosion includes both the detachment and transport of soil particles.
(3) Erosion Control Measures. All measures necessary to minimize soil erosion and to control sedimentation in the disturbed land area shall be provided, which includes obtaining any appropriate state and/or federal erosion control permits. Specifically, the following protection shall be provided for all disturbed areas: Minimize velocities of water runoff, maximize protection of disturbed areas from stormwater runoff, and retain sedimentation within the development site as early as possible following disturbances. A list of major problem areas for erosion and sedimentation control follows. For each one, the purpose(s) of requiring control is described. Soil erosion and sedimentation control measures for all such areas shall be provided with a view toward achieving the specific purpose listed below for which a control plan is required.
(a) Erodible Slopes. Prevent detachment and transportation of soil particles from slope.
(b) Streams, Streambeds, Streambanks, Bodies of Water, Shorelines. Prevent detachment and transportation of soil particles.
(c) Drainageways. Prevent detachment and transportation of soil particles (which would otherwise deposit in streams, bodies of water, or wetland); promote deposit or sediment loads (traversing these areas) before these reach bodies of water.
(d) Land Adjacent to Streams, Ponds, Lakes, and Wetlands. Prevent detachment and transportation of soil particles.
(e) Enclosed Drainage Structure. Prevent sedimentation in structure, erosion at outfall of system and deposit of sediment loads within system or beyond it.
(f) Large Flat Surface Areas (Unpaved). Prevent detachment of soil particles and their off-site transportation.
(g) Impervious Surfaces. Prevent the detachment and transportation of soil (in response to an increase in the rate and/or volume of runoff of the site or its concentration caused by impervious surfaces).
(h) Borrow and Stockpile Areas. Divert runoff from face of slopes which are exposed in the excavation process; convey runoff in stabilized channels to stable disposal points; leave borrow areas and stockpiles in stable condition.
(i) Adjacent Properties. Prevent their erosion and/or being deposited with sediment. [Ord. 508 § 5.04.6, 1982].