Chapter 17.54
Hazards and Shoreline/Bluff Development
Sections:
17.54.030 Limitations on Development
17.54.040 Application Requirements
17.54.050 Site Planning and Project Design
17.54.060 Shoreline Protection Structures
17.54.070 Floodplain Development
17.54.010 - Purpose
This Section provides requirements to ensure that development in the Coastal Zone shall:
A. Minimize risks to life and property in areas of high geologic, fire, and flood hazard;
B. Ensure structural integrity and stability; and
C. Neither create nor contribute significantly to erosion, geologic instability, or destruction of the site or surrounding area, nor in any way require the construction of protective devices that would substantially alter natural landforms along bluffs and cliffs.
17.54.020 - Applicability
The provisions of this Chapter apply to all development and new land uses proposed on blufftop and shoreline parcels and within areas of high geologic, fire, and flood hazard.
17.54.030 - Limitations on Development
A. Prohibition on development needing protection. Proposed development shall not be approved where the review authority determines that shoreline protective structures will be necessary to protect the new structures at the time of development, or within 100 years of development.
B. Public structures. All development, including stairs, retaining walls, fences, pipelines, and similar public or quasi-public facilities located on coastal bluffs shall require a Coastal Permit.
17.54.040 - Application Requirements
Land use permit applications for development on blufftop and shoreline parcels shall include the following information where applicable, in addition to all the information required by Section 17.70.040 (Application Preparation and Filing) and 17.71.045 (Coastal Development Permit).
A. Erosion control plan. All land use permit applications for blufftop and shoreline parcels shall include a site specific erosion control plan. The plan shall be prepared by a registered engineer qualified in hydrology and soil mechanics, and shall ensure that the development will not create nor contribute to the erosion or failure of any bluff face, and will eliminate or mitigate any adverse impacts on local shoreline sand supply to the maximum extent feasible.
B. Geology report. Applications for blufftop and shoreline development located in or near an area subject to geologic hazards, including but not limited to, areas of geologic hazard shown on Map SF-1 of the Coastal General Plan, shall be required to submit a geologic/soils/geotechnical study that identifies all potential geologic hazards affecting the proposed project site, all necessary mitigation measures, and contains a statement that the project site is suitable for the proposed development and that the development will be safe from geologic hazard.
C. Preparation and contents of geology report. A required geology report shall be prepared by a qualified, licensed Certified Engineering Geologist (CEG) or Geotechnical Engineer (GE) approved by the City, and shall be submitted with the planning permit application for the proposed development. The report shall consider, describe, and analyze the following:
1. Cliff geometry and site topography, extending the surveying work beyond the site as needed to depict unusual geomorphic conditions that might affect the site;
2. Historic, current, and foreseeable cliff erosion, including investigation of recorded land surveys and tax assessment records in addition to the use of historic maps and photographs where available, and possible changes in shore configuration and sand transport;
3. Geologic conditions, including soil, sediment, and rock types and characteristics, in addition to structural features such as bedding, joints, and faults;
4. Evidence of past or potential landslide conditions, the implications of such condition for the proposed development, and the potential effects of the development on landslide activity;
5. Impact of construction activity on the stability of the site and adjacent area;
6. Ground and surface water conditions and variations, including hydrologic changes caused by the development (e.g., introduction of sewage, effluent, and irrigation water to the groundwater system, alterations to surface drainage, and the like);
7. Potential erodibility of the site and mitigation measures to be used to ensure minimized erosion problems before and after construction (i.e., landscape and drainage design);
8. Effects of marine erosion on the coastal bluffs
9. Potential effects of seismic forces resulting from a maximum credible earthquake;
10. Any other factors that might affect slope or bluff stability.
11. Whether the proposed project will be subject to or contribute to significant geologic instability throughout the 100-year life span of the project;
12. Effects of future sea level rise on the development;
13. Slope stability and bluff erosion rate determination performed as outlined in Section E and F below; and
14. An alternatives analysis of, and mitigation measures for, all potential impacts.
In addition to all applicable information required by section (C)(1)-(14) above, all applications for new shoreline structures shall include an analysis of beach erosion, wave run-up, and tsunami and flood hazards prepared by a licensed civil engineer with expertise in coastal engineering. These reports shall address and analyze the effects of said development in relation to the following:
15. The profile of the beach;
16. Surveyed locations of mean high tide lines acceptable to the State Lands Commission;
17. The availability of public access to the beach;
18. The area of the project site subject to design wave run-up, based on design conditions;
19. Foundation design requirements;
20. The long-term effects of proposed development on sand supply;
21. The FEMA Base Flood Elevation and other mapped areas (A,B, or V zones);
22. Future projections in sea level rise; and
23. Project alternatives designed to avoid or minimize impacts to public access.
D. Public Access information. Applications for blufftop or shoreline development, including but not limited to shoreline protective structures, shall include a site map that shows all existing easements, deed restrictions, or OTD’s and/or other dedications for public access or open space and provides documentation that the development shall be located outside of and consistent with the provisions of such easement or offers.
E. Slope Stability Analysis. For the purpose of this section, quantitative slope stability analyses shall be undertaken as follows:
1. The analyses shall demonstrate a factor of safety greater than or equal to 1.5 for the static condition and greater than or equal to 1.1 for the seismic condition. Seismic analyses may be performed by the pseudostatic method, but in any case shall demonstrate a permanent displacement of less than 50 mm.
2. Slope stability analyses shall be undertaken through cross-sections modeling worst case geologic and slope gradient conditions. Analyses shall include postulated failure surfaces such that both the overall stability of the slope and the stability of the surficial units is examined.
3. The effects of earthquakes on slope stability (seismic stability) shall be addressed through pseudostatic slope analyses assuming a horizontal seismic coefficient of 0.15g, and shall be evaluated in conformance with the guidelines published by the American Society of Civil Engineers, Los Angeles Section (ASCE/SCEC), “Recommended Practices for Implementation of DMS Special Publication 117, Conditions for Analyzing and Mitigating Landslide Hazards in California.”
4. All slope analyses shall be performed using shear strength parameters (friction angle and cohesion), and unit weights determined from relatively undisturbed samples collected at the site. The choice of shear strength parameters shall be supported by direct shear tests, triaxial shear test, or literature references.
5. All slope stability analyses shall be undertaken with water table or potentiometric surfaces for the highest potential ground water conditions.
6. If anisotropic conditions are assumed for any geologic unit, strike and dip of weakness planes shall be provided, and shear strength parameters for each orientation shall be supported by reference to pertinent direct sheer tests, triaxial shear test, or literature.
7. When planes of weakness are oriented normal to the slope or dip into the slope, or when the strength of materials is considered homogenous, circular failure surfaces shall be sought through a search routine to analyze the factor of safety along postulated critical failure surfaces. In general, methods that satisfy both force and moment equilibrium (e.g., Spencer, Morgenstern-Price, and General Limit Equilibrium) are preferred. Methods based on moment equilibrium alone (e.g., Bishop’s Method) also are acceptable. In general, methods that solve only for force equilibrium (e.g., Janbu’s method) are discouraged due to their sensitivity to the ratio of normal to shear forces between slices.
8. If anisotropic conditions are assumed for units containing critical failure surfaces determined above, and when planes of weakness are inclined at angles ranging from nearly parallel to the slope to dipping out of slope, factors of safety for translational failure surfaces shall also be calculated. The use of a block failure model shall be supported by geologic evidence for anisotropy in rock or soil strength. Shear strength parameters for such weak surfaces shall be supported through direct shear tests, triaxial shear test, or literature references.
9. The selection of shear strength values is a critical component to the evaluation of slope stability. Reference should be made to American Society of Civil Engineers, Los Angeles Section (ASCE/SCEC), “Recommended Practices for Implementation of DMS Special Publication 117, Conditions for Analyzing and Mitigating Landslide Hazards in California.” when selecting shear strength parameters.
F. Bluff Retreat Rate. For the purpose of this section, the long-term average bluff retreat rate shall be determined by the examination of historic records, surveys, aerial photographs, published or unpublished studies, or other evidence that unequivocally show the location of the bluff edge through time. The long-term bluff retreat rate is an historic average that accounts both for periods of exceptionally high bluff retreat, such as during extreme storm events, and for long periods of relatively little or no bluff retreat. Accordingly, the time span used to calculate a site-specific long-term bluff retreat rate shall be as long as possible, but in no case less than 50 years. Further, the time interval examined shall include the strong El Nino winters of 1982-1983, and 1997-1998.
The expected bluff retreat rate over the expected life of the development shall be based in part on the historic bluff retreat rate, but shall also include consideration of the effects of continued historic rates of sea level rise, potential accelerated sea level rise, increase in significant wave heights, and increase in storm intensity and frequency, as is expected under most scenarios of the Intergovernmental Panel on Climate Change.
17.54.050 - Site Planning and Project Design
A. Design. All development adjacent to coastal bluffs and the beach shall be sited and designed to reduce the visual impact of bulk and scale.
B. Height limits. Height limits for structures on blufftop and shoreline parcels are established by the applicable zoning district.
C. Setbacks. Development proposed on blufftop and shoreline parcels shall comply with the setback requirements of the applicable primary zoning district, and shall also comply with the required set back from the top of the bluff as provided by this Subsection.
1. Bluff retreat setback requirements. All new development located on a blufftop shall be setback from the bluff edge a sufficient distance to ensure that it will be stable for a projected 100-year economic life. This entails an assurance that a factor of safety against slope instability of 1.5 (static) and 1.1 (pseudostatic) shall be maintained for the economic life of the development as determined by a site-specific geology report, prepared in compliance with Section 17.54.040.C (Preparation and contents of Geology Report); provided that in no case shall the minimum setback be less than 25 feet. Stable shall be defined as maintaining a minimum factor of safety against sliding of 1.5 (static) and 1.1 (pseudostatic) as defined in Section 17.54.040 (E). This requirement shall apply to the principal structure and accessory or ancillary structures. Slope stability analysis and erosion rate estimates shall be performed by a licensed Certified Engineering Geologist or Geotechnical Engineer.
2. Bluff Face and bluff retreat setback development. Prohibit development within the bluff retreat setback and on a bluff face except that the following uses may be allowed with a conditional use permit:
a. engineered accessways or staircases to beaches, boardwalks, viewing platforms, and trail alignments for public access purposes;
b. pipelines to serve coastal dependent industry;
c. habitat restoration;
d. hazardous materials remediation; and
e. landform alterations where such alterations re-establish natural landforms and drainage patterns that have been eliminated by previous development activities.
All allowable ocean-front and blufftop development shall be supported by findings that no feasible less environmentally damaging alternative is available and that feasible mitigation measures have been provided to minimize all adverse environmental impacts. Require as a part of the coastal development and conditional use permit applications, a full environmental, geological, and engineering review. Such structures shall be constructed and designed to not create nor contribute to erosion of the bluff face and to be visually compatible with the surrounding area to the maximum extent feasible.
3. Access and recreational area setbacks. Additional blufftop setbacks may be required in compliance with Local Coastal Plan policies to accommodate public access and recreational areas, in compliance with Chapter 17.56 (Shoreline Access).
D. Drainage and Erosion control. Proposed blufftop and shoreline development shall be designed and constructed to incorporate appropriate drainage and erosion control measures, in compliance with the City’s grading standards and shall include measures to insure that:
1. No stockpiling of soil or construction materials shall occur on the shoreline;
2. All grading shall be properly covered and sandbags and/or ditches shall be used to prevent runoff and siltation;
3. Measures to control erosion shall be implemented at the end of each day’s work;
4. No machinery shall be allowed in the intertidal zone at any time to the extent feasible;
5. All construction debris shall be removed from the beach.
6. All development shall provide adequate drainage and erosion control facilities that convey site drainage in a non-erosive manner in order to minimize hazards resulting from increased runoff, erosion and other hydrologic impacts to streams.
7. All development shall:
a. avoid creating concentrated runoff, particularly over steep slopes and bluff faces, by locating and directing drainage away from the bluff face and by installing energy dissipating devices;
b. create drainage swales, detention, and retention basins where appropriate;
c. control the timing and manner of new construction so that there are no bare soil slopes during the rainy season.
E. Structures on sandy beach. No permanent structures shall be permitted on a dry sandy beach except facilities necessary for public health and safety, including lifeguard towers.
F. Deed Restriction. All ocean-front and blufftop development shall be sized, sited and designed to minimize risk from wave run-up, flooding and beach and bluff erosion hazards and avoid the need for a shoreline protection structure at any time during the life of the development. To inform future owners of such restrictions, the property owner shall be required to record a deed restriction against the property that ensures that no shoreline protection structure shall be proposed or constructed to protect the development approved and which expressly waives any future right to construct such devices that may exist pursuant to Public Resources Code Section 30235 or the provisions of the certified LCP.
In areas where the City, or Coastal Commission on appeal, determines that there are geologic hazards, a development permit shall not be issued until the applicant has signed as a condition of coastal permit approval, a waiver of all claims against the City, or Coastal Commission on appeal, for future liability or damage resulting from permission to build. All such waivers shall be recorded on the deeds for subject properties.
17.54.060 - Shoreline Protection Structures
A. Prohibition of Shoreline Structures. Revetments, breakwaters, groins, harbor channels, seawalls, cliff retaining walls, and other such construction that alters natural shoreline processes shall be prohibited unless the review authority determines that the structure is:
1. required (1) to serve coastal-dependent uses, or (2) to protect public beaches in danger from erosion, or (3) to protect existing structures that were legally constructed prior to the effective date of the Coastal Act, or that were legally permitted prior to the effective date of this Coastal General Plan provided that the CDP did not contain a waiver of the right to a future shoreline or bluff protection structure, or (4) for a development consistent with Section 30233(a) of the Coastal Act;
2. The least environmentally damaging feasible alternative;
3. Designed to successfully eliminate or mitigate adverse impacts on local shoreline sand supply;
4. Designed to avoid significant rocky points and intertidal or subtidal areas;
5. Designed to provide lateral beach access, where feasible;
6. Designed to respect natural land forms and minimize visual impact to the extent possible, through means including the use of visually compatible colors and materials; and
7. Designed to avoid interference with commercial or recreational boating traffic.
17.54.070 - Floodplain Development
A. Floodplain development. Development within an identified floodplain in the Coastal Zone, including but not limited to those areas shown on Map SF-2, shall be limited to those uses allowed in the Open Space land use designation consistent with all other applicable requirements of the LCP.
1. Standards for all uses. Each use shall be designed to minimize danger of loss of life and property during a flood, both on and downstream from the site.
2. Pudding Creek area. No new development shall be allowed within the 100 year flood plain portions of the Pudding Creek hazard area, as identified by the Coastal General Plan.