DECEMBER 1993
This report was prepared by the staff of the California Coastal Commission as part of a Project of Special Merit for the Office of Coastal Resource Management of the National Oceanic and Atmospheric Administration. It has not been approved by the Commission.
TABLE OF CONTENTS
I. INTRODUCTION
II. COASTAL ACT POLICIES AND INTERPRETIVE GUIDELINES THAT ADDRESS LAND FORM ALTERATION
II.A. CALIFORNIA COASTAL ACT POLICIES ON LAND FORM ALTERATION
II.B. REGIONAL INTERPRETIVE GUIDELINES
III. LCPs AND APPROACHES TO LAND FORM ALTERATION
IV. OTHER PLANNING TOOLS WHICH ADDRESS LAND FORM ALTERATION
V. REGULATIONS OR STANDARDS WHICH ADD TO LAND FORM ALTERATION
VI. CONCLUSIONS
The alteration of natural land forms often results in significant impacts on coastal resources, such as erosion and siltation into streams or wetlands, visual scarring of scenic areas or reduction of biologic productivity. The alteration of natural land forms and the impacts from such alteration were raised as concerns during the development of the California Coastal Plan and subsequently in the preparation and implementation of the Coastal Act. This concern carried into the regional interpretive guidelines and the certified Local Coastal Programs (LCPs). These elements, the California Coastal Act, the Regional Interpretive Guidelines, and the LCPs encompass the Commission's regulatory policies that relate to land form alteration.
The Coastal Act, Commission regulatory decisions, and certified LCPs have worked, through decisions, policy guidance, or regulations to avoid or mitigate the negative impacts from land form alteration. On the other hand, requirements from other agencies such as Fire Districts or local government engineers may require land form alteration for roads, water tanks, etc. in excess of what the Commission would otherwise find acceptable, resulting in significant negative impacts of coastal resources and an inconsistent decision-making process for applicants.
No regulations or policies require that land form alteration be maximized; however, there are various safety regulations which often establish development standards that are normally met through land form alteration. Developed land must provide safe access, manageable by fire equipment, access to water and electric service, either sewer access or on-site septic, and a cleared area for structures and their foundations. While it is often relatively easy to provide these needs for a flat or lowland site without substantial land form alteration, it can often be difficult to do so on steep slopes or in areas prone to landslides. Typically, access to and development of steep slope areas has been achieved with massive cut and fill slopes to level out the land, and slope instability has been corrected through either removal and recompaction of the slide material or construction of a large buttress fill. Significant land form alteration is a result or by-product of these efforts.
This report discusses:
- the overall guidance which was given to local governments concerning land form alteration, through the California Coastal Act and the Regional Interpretive Guidelines
- general techniques used in the LCPs to address land form alteration, and
- other policies and practices which tend to conflict with efforts to minimize land form alteration.
This report is the second of three reports prepared to examine the policy aspects of land form alteration. The first report identified many of the problems which can occur from excessive land form alteration. The final report will be policy guidance for land form alteration. These three policy reports have been prepared to complement an earlier technical report which provided an overview of engineering techniques which can be used to minimize grading.
II. COASTAL ACT POLICIES AND INTERPRETIVE GUIDELINES THAT ADDRESS LAND FORM ALTERATION
A. CALIFORNIA COASTAL ACT POLICIES ON LAND FORM ALTERATION The California Coastal Act (Cal. Pub. Res. Code Sections 30000 et seq.)[1], the foundation of the California Coastal Management Program (CCPM)[2], was enacted by the State Legislature in 1976 to provide for the conservation and development of the state's 1,100-mile coastline. The Act established the California Coastal Commission as a permanent state coastal management and regulatory agency and created a unique state and local government partnership to assure that public concerns of statewide importance are reflected in local decisions about coastal development. The Coastal Act contains specific policies establishing standards to which coastal development must conform (Sections 30200 - 30264; 30700 - 30721). These policies relate to land and water use, natural resources, industrial and residential development, energy, public access and recreation, transportation, agriculture, offshore oil development and other used of the coastal zone.
Authorities In carrying out the objectives and policies of the Coastal Act, the Coastal Commission delegates much of its authority to control coastal development to local government. Coastal Act Section 30004 declares that:
to achieve maximum responsiveness to local conditions, accountability, and public accessibility, it is necessary to rely heavily on local government and local land use planning procedures and enforcement.
To this end, the Act directs the cities and counties lying wholly or partly within the coastal zone to prepare for Commission review and certification a Local Coastal Program (LCP) for local government's portion of the coastal zone. Following LCP certification, the local government assumes responsibility for administering coastal development permits (CDPs) within its jurisdiction in the coastal zone subject to limitations set forth in Section 30519[3]. Coastal Act policies or the policies in an approved LCP establish the criteria for granting or denying permits in a given area.
Although the Commission delegates certain authority to local governments, the Commission retains several well-defined regulatory responsibilities. For example, the Commission:
Commission authority over land form alteration projects The Coastal Act's primary direction relating to land form alteration in presented in Section 30231 which states that "biological productivity ... shall be maintained and, where feasible, restored through ...... controlling runoff, ..., maintaining natural vegetation buffer areas that protect habitats and minimizing alteration of natural streams," and Section 30251 which states that, "Permitted development shall be sited ... to minimize the alteration of natural land forms ... ".Both of these sections direct the Commission to address effects to land forms and drainage in its review of projects. In addition, land form alteration can directly or indirectly impact many other resources such as Environmental Sensitive Habitat Areas, riparian habitat, archaeological resources, all of which are addressed by the Coastal Act. A detailed discussion of the environmental ipcts from land form alteration can be found in the Commission's March 1993 report," Landform Alteration Policy Concerns".
The Coastal Commission may become involved in the process of reviewing permits for land form alteration in a number of ways. The following is a brief overview of provisions for Commission involvement.
1) If the proposal includes development[4] in an area of the coastal zone[5] where the city of county does not have a fully certified LCP, a CDP from the Coastal Commission will be required under Coastal Act Section 30600(a).
(2) The Commission retains permit jurisdiction over any portion of a project that is in state waters, on land up to the mean high tide line, or on lands subject to the public trust. If development is proposed within these areas, a Commission permit will be required.
(3) The Commission will review LCP amendments that provide for land form alteration or development which could lead to land form alteration.
(4) In areas where there is a certified LCP, a proposed project may be appealable to the Commission under the appeal provisions of Coastal Act Section 30603.
B. REGIONAL INTERPRETIVE GUIDELINES: Regional interpretive guidelines have been adopted by the California Coastal Commission to assist in applying the policies of the Coastal Act (Act) to proposed development prior to certification of an LCP and provide guidance for preparation of an LCP which could be certified. Regional interpretive guidelines were adopted for most of the Coastal Zone between 1978 and 1981, but there are some areas within the Coastal Zone (Del Norte, Mendocino, Humboldt, and San Mateo Counties) for which Interpretive Guidelines have not been prepared. The regional interpretive guidelines commonly recommend policies or techniques which limit natural land form alterations or grading within the Coastal Zone. The methods of development guidance are grouped under headings: Steep Slope Development, Ridge or Bluff Development, Habitat Protection and General Development Guidelines.
For most areas, the Regional Interpretive Guidelines have been replaced or supplanted by Land Use Plans (LUP) or LCPs. These locally prepared plans may modify or completed change the recommendations made in the Regional Guidelines, but usually maintain the general intent of the guidelines. The summary of the Regional Guidelines is followed by a second summary of the land form alteration policies of the LCPs.
North Central Coast Region (Sonoma, Marin and San Francisco Counties)
The interpretive guidelines for the North Central Coast provide guidance for land form alteration, erosion/sediment control, and slope development on a community by community basis.
Steep Slope Development
Ridge or Bluff Development
Habitat Protection
General Development Guidelines
Central Coast Region (Santa Cruz and Monterey Counties)
Interpretive guidelines for the Central Coast Region provide development controls on a generalized basis. Specific development guidelines and design standards for development within the Coastal Zone were provided as appendices. The design guidelines contained in the appendices cover limits of site disturbance, site coverage, impervious surface area, seasonal grading limitation, slope modification restriction and requirements that applications include: topography, limits of disturbance, surface coverage, and impervious surfaces, location of septic, and proposed landscaping.
Steep Slope Development
Ridge or Bluff Development
Habitat Protection
General Development Guidelines
South Central Coast Region (Cayucos, Morro Bay, and Oceano Beach)
Regional Interpretive Guidelines for the South Central Region provide both site specific and generalized development restrictions.
Steep Slope Development
Ridge or Bluff Development
Habitat Protection
General Development Guidelines
South Coast District (Malibu -Santa Monica Mountains)
The District Interpretive Guidelines for Malibu and the Santa Monica Mountains are very comprehensive, making reference to specific areas within the district and as well as providing generalized development guidance for the whole district. The guidelines identify "Significant Ecological Areas (SEAs), buffer areas for the SEAs, a mechanism for transfer of development credits, calculations for allowable gross structural area, road and driveway designs, fuel modification, fire/emergency access guidelines, stream alteration restrictions, bluff top development, and buffer areas.
Steep Slope Development
Ridge or Bluff Development
Habitat Protection
General Development Guidelines
South Coast Region (Los Angeles)
The South Coast Region Interpretive guidelines prepared for the Los Angeles area, excluding Malibu and the Santa Monica Mountains, provide development direction on an area specific basis. The guidelines for individual areas refer almost exclusively to standardized development restrictions contained in the appendices.
Steep Slope Development
Ridge or Bluff Development
Habitat Protection
General Development Guidelines
South Coast Region (Orange County)
Interpretive Guidelines for the Orange County Region utilize the same format as the Los Angeles Region with development restrictions contained in appendices.
Steep Slope Development
Ridge or Bluff Development
Habitat Protection
General Development Guidelines
San Diego Region
Interpretive Guidelines for the San Diego Region refer to specific areas; however, provide little or no guidance on limitation for grading and stream alteration restriction.
Steep Slope Development
Ridge or Bluff Development
Habitat Protection
General Development Guidelines
Local governments have addressed land form alteration for many years through planning, zoning, and ordinances. While the Coastal Act heightened local governments' awareness of the concern for land form alteration, many of the regulatory techniques to minimize such alteration were already being used by local governments. For example, the City of Los Angeles adopted the first grading ordinance in 1952, in response to destructive rains during the 1951-52 winter, and in 1966 Los Angeles County adopted a brush removal ordinance for hilly and mountainous areas. Chapter 70 of the Uniform Building Code was first issued in 1964 to provide guidance on minimum safety standards for cut, fill and excavations. And many local governments had existing zoning and ordinances to address some or all of the concerns for steep slope development and land form alteration which they incorporated in their LCPs.
Probably the most significant effort to address the minimizing of land form alteration is through controls on steep slope development and efforts to protect sensitive habitat. The following discussion is a general overview of techniques or approaches taken throughout the coast. A portion of this discussion is taken from a September 28, 1984 Memorandum to the Commissioners and Interested Parties from Jim McGrath, Coastal Program Analyst, relating to Development Restrictions on Steep Slopes.
Within California there are 126 existing LCP segments. Of those, 104 have an effectively certified Land Use Plan, 85 effectively certified Implementation Plans and 81 have certified LCPs and are issuing permits (from Annual LCP Status Report, as of July 1, 1993, presented to the Commission August 31, 1993.). While only 64% of the total segments have fully certified LCPs, these segments cover 85% of the coast, by geographic area. "There are a number of areas within the Coastal Zone which for one reason or another have not been included in an LCP (or any segment thereof) and will need to be addressed at some time in the future." These areas are mostly fully developed areas, such as Wilmington, which make up a small geographic portion of the coastal zone. These areas, along with Areas of Deferred Certification and uncertified LCP segments receive project review based on the Coastal Act, with planning assistance as needed from the Interpretive Guidelines and relevant effectively certified Land Use or Implementing Plans.
Most of the Del Norte County coastal zone is a gently sloping coastal terrace, or is lands that are in public ownership and managed for public recreation or resource protection. The LCP for Del Norte County developed generalized stability maps which indicate areas where further stability analysis or foundation investigations should be made for roads, subdivision or critical structures. Geologic reports are required for all development, including roads, in landslide prone areas, and high hazard areas should be used for recreation, open space and low intensity park activities, if feasible. Residential development is discouraged on slopes that exceed 30%, and "modifications of hills to the north and east of Smith River should be undertaken only after a qualified assessment is made of the potential for upsetting the tenuous natural balance." (Del Norte County LCP, pg. 216)
Unlike Del Norte County, Humboldt County has a number of steep areas that are regulated in the LCPs to protect resources. The grading requirements in Chapter 70 of the Uniform Building Code are followed throughout the county. To protect natural land forms, topography must be restored as closely as possible to natural contours and it should be revegetated. Access roads and utility corridors should follow natural contours and in hilly areas, minimum street widths can be waived if the reductions are consistent with public safety. Large portions of the county are forested and the LCP incorporated county wide efforts to adopt "best management practices" to protect and conserve timber soils and limit the intensity of development in timber and other steep slope areas.
The Trinidad LCP requires that no structures, septic tanks or driveways be placed on unstable soils, and that structures, septic tanks or driveways be placed on lands of questionable stability or within 100 feet upslope of unstable lands only if a geologist indicates that the proposed development will not significantly increase erosion, slope stability of septic failure. In sensitive or scenic areas, vegetation removal is limited to than allowed by the City Engineer to address imminent hazard. No slab foundations can be used on slopes greater than 15%; no development is allowed on portions of lots with slope greater than or equal to 20% or in areas requiring access on slopes greater than or equal to 20%.
Mendocino County has both grading and erosion standards. The LCP uses development overlays to address various resource protection or development constraint needs. The maximum lot coverage is based on a percentage of the parcel size and each zoning category requires minimum lot sizes, setbacks, building heights, accessory uses and dwelling density. No development is allowed for slopes greater than 30% unless evidence is given by a civil engineer that no increased erosion will occur. Development in areas that results in hazardous road cuts shall not be allowed; roads should follow ridge lines when possible. The Mendocino County LCP also requires a permit from the Planning Director for major vegetation removal and harvesting, where major removal is considered to be removal of vegetation from a slope greater than 15% or adjacent to an ESHA, removal of trees with contiguous ground cover of 6,000 sq. ft., or removal of more than 15 trees or more than 10% of the total trees with diameter of 12" of more, at breast height.
Much of the Sonoma County coastal zone is agricultural lands and the general approach to resource protection is a strict limitation on development and parcel size in areas suitable for agriculture. Development controls are established for continued build-out of existing subdivisions. Rural residential densities are based on both water and sewer availability, and maximum lot coverage is 35% regardless of lot size. Site development provisions were proposed for the entire county, but were never adopted; therefore, some of the development provisions for the coastal zone are not mirrored by similar county-wide provisions. Within the county, all lot development proposals are reviewed individually, and there are no absolute provisions against steep slope development for reasons of grading impacts or site disturbance. For reasons of health and safety, no leach fields are allowed on lands steeper than 30%.
In the coastal zone there may be no development or grading on slopes greater than 30% (unless this restriction would completely prohibit development on a legal lot) and site development must follow the guidelines provided in the Erosion and Sediment Control Handbook, prepared by Perry Amimoto for the State of California Conservation Department. Grading permits are required for exploratory excavations exceeding 200 sq. ft., cleared vegetation exceeding 1,000 sq. ft., excavation exceeding 4 ft. vertical depth or a fill slope exceeding 5 ft. in height. There can be no disturbance of native vegetation more than 15 days prior to grading and exposure must be limited to the area of immediate construction. All residential development greater than 1,000 sq. ft. must be served by an all-weather road with a minimum width of 12 ft., maximum grade of 15% and turnouts every 300 ft. if designed as a single lane road.
Sea Ranch is a 5,200 acre low-density residential development in Sonoma County. A Sea Ranch Review Committee has developed design guidance, requiring that homes be sited to take advantage of natural land forms and vegetation, that buildings be clustered in some areas to achieve screening and greater open space. The overriding aim of the Sea Ranch Review Committee is to insure that new development is visually compatible with existing development and the rural setting. Much of the visual concern leads to minimization of land form alteration through the protection of native vegetation, avoidance of development of ridge lines and encouragement of natural landscape compatibility.
The basis resource protection approach in Marin County is similar to that of Sonoma County -- protection of agricultural areas by limiting development and parcel size. The County's grading policies apply to all projects involving 150 cubic yards or more of grading and they require that development be designed to fit the site's topography and that grading, cut and fill operations be kept to a minimum. No construction, land form alteration or vegetation removal is allowed in riparian protection areas and the only alteration of stream channels shall be for water supply or flood impoundment, where no other protection is possible. Development plans shall include sediment, erosion, runoff controls and revegetation measures, and all sediment shall be retained on site. No limits are placed on the time that grading can occur; however, land clearing in the rainy season is discouraged and stabilizing slopes shall be in place before the beginning of the rainy season.
In Marin County, road construction is believed to have a greater impact on land resources than the subsequent construction of houses. The County's grading policy strictly limits creation of new lots and development of existing steep lots on ridges. No construction is permitted on top or within either 100 ft. vertical or 300 ft. horizontal of visually prominent ridges if other suitable locations are available. Finally, the County recognizes that many lots are characterized by one or more geologic hazards and thus conditions many permits to make clear that the permit is not a warrant of the property's safety and requires that a waiver of liability be executed.
San Mateo County has county Regulations of Grading and Excavation Operations and well as Topsoil Regulations. The LCP requires that new development, roads and other structural improvements be designed to fit the natural topography to minimize grading. Private drives should be shared, where possible and development should be prohibited where it requires grading that would substantially alter or destroy the appearance of natural land forms. Maximum densities are determined from the slope of the site and the existence of geologic constraints such as landslides or active faults. In Half Moon Bay, Dystra Ranch, there can be no development on slopes in excess of 25% or above the 160 ft. contour.
On slopes of 30% or greater, development, including land division that would create steep slope parcels, should be prohibited, unless no alternative exists. If development must be sited on steep slope lots, engineering geology reports shall be required to minimize hazards and the Design Review Zoning Ordinance and Community Design Manual for Development on Slopes 30% or Greater shall be followed. In addition to concern for steep slopes, the County has developed a Geologic Hazard District which overlays zoning maps for areas of landslide and seismic hazard. Development in such areas requires a geotechnical investigation and no permit shall be approved until it has been approved by the County geologist and a deed restriction has been recorded.
Santa Cruz County included the steep, heavily wooded Santa Cruz mountains. Policies regulating development on steep slopes include the prohibition of discretionary development on slopes greater than 30% and require a geologic hazard assessment in all cases where development is planned on slopes greater than 30%. Erosion policies exclude lands with slopes greater than 30% in urban areas and greater than 50% in rural areas from density calculations for land division purposes. The County also uses an Urban Open Space designation for various lands, including slopes over 30%. Site slopes are a component of the County's Density Determination Matrix system for guiding development in rural areas, with distinctions made for different slopes, soil types, landslide potential, proximity to a fault zone, availability of utilities, and others. (from McGrath, 9/28/84)
All exposed soils must be protected from October 15th to April 15th; all disturbed sites must be stabilized and all erosion and sediment must be controlled on site. Site disturbance must be limited to 25% of the site, with final disturbance after revegetation limited to 15%; and impervious surfaces must be limited to 10%. The County has guidelines for development in steep slope areas, such as clustering development and limiting the size of cut or fill slopes to less than 10 feet. Step or pole foundations should be used for slopes greater than 15% and pole foundations only for slopes greater than 30%. Roads must be at least 16' wide, or 12' with turnouts that are approved by the fire department; no access roads may cross slopes steeper than 30%. Erosion control plans are required for any clearing more than one acre, except for existing agriculture. For areas with high erosion potential, final site development, drainage and erosion control plans must be prepared and approved prior to any clearing or grading activity.
The Monterey County coastal zone encompasses much of the Elkhorn Slough watershed and extends far inland in the north part of the county. Much of the concern in this area is for erosion and sedimentation controls, resulting primarily from agricultural practices. The certified North County LCP uses slopes to establish development standards, protect vegetation, require soils and geologic reports and reduce or mitigate erosion in each sub-watershed. Slopes greater than 25% are designated as Critical Erosion Areas, as are other soils of high erosion potential. Development must avoid these Critical Erosion Areas, unless avoidance is not possible. No oak woodland or chaparral may be removed from slopes steeper than 25%.
Southern Monterey County is a relatively undeveloped area and visual quality and habitat protection are significant concerns. The overall regulatory approach to development in the southern part of the county is to establish low intensity development, with 1 unit per 40 acres for slopes less than 15%, 1 unit per 80 acres for slopes between 15 and 30% and 1 unit per 320 acres for slopes greater than 30%. There is also a county-wide restriction against grading during the winter months, between October 15th and April 15th.
San Luis Obispo County has a very rural character, with rather large land holding throughout much of the county. To protect the visual character of the area, development is prohibited on slopes greater than 20% in all rural areas, or in areas outside central Pismo Beach and Morro Bay. No grading is permitted in the county from November through March, and revegetation must be started as soon as possible after grading is completed. Road alignments are to be designed and constructed to minimize terrain disturbance, consistent with safety and construction costs. The LCP provides maps of Geologic Study Areas where geologic and soils studies are required for approval of new development.
Much of Santa Barbara County is also rural, with large agricultural land holdings; concentrated development is limited to the major urban centers. Two of the dominant concerns in Santa Barbara which affect land use planning are water availability and agricultural lands preservation. No new land subdivisions are allowed unless the applicant can demonstrate that adequate water is available to serve the newly created lots, except for lots designated as "Not A Building Site". Several communities in Santa Barbara County have developed Community Plans to address decisions of land use and resource protection. For example, Goleta's Community Plan provides protection of many upland areas through habitat protection policies. Two hundred foot buffers are required the in Mountainous GOL for riparian vegetation in which grading and vegetation removal shall be limited, consistent with the purpose and intent of the overlay district. Throughout the entire community, excessive grading for the sole purpose of creating or enhancing views shall not be permitted.
In much of the north part of the county the minimum lot sizes are 100 or 320 acres, and a Slope Density Curve is used throughout the county for lot development. Structures shall be subordinate in appearance to natural land forms and no above ground structure, except utilities or agricultural fences may be sited on undisturbed slopes exceeding 40%. A Brush Removal Permit is required for construction of service roads or clearing of natural vegetation for orchards on slopes greater than 20%. If major vegetation removal on slopes steeped than 20% is proposed for non-agricultural development, the Soil Conservation Service must be consulted and their recommendations should be followed. Projects requiring grading may be denied if it is determined that the development can be carried out with less alteration of natural terrain and areas which, due to hazardous conditions , are not suitable for development, should remain open space. When grading is undertaken, the exposed areas should be as small as practicable and shall be quickly revegetated. No site clearing can occur during the winter months and all eroded sediments should be retained on site or moved to an appropriate dumping location.
The most significant steep slope area in Ventura County is the Santa Monica Mountains. This zone also includes a narrow portion of the frontal slope of the Santa Inez Mountains along the north coast. In these areas, the county uses a slope density formula for new development, requiring at least 10 acres per unit for slopes less than 15% to 100 acres per unit for slopes greater than 35%, average slope. In addition, many upland habitat areas have been mapped for protection and areas with slope greater than 30% are to be preserved as open space. Development is not to intrude onto ridge lines, or into the view sheds of public recreation areas. Grading is not permitted from November 15th to April 15th. (from McGrath, 9/28/84)
Much of the Santa Monica Mountains extend south into Los Angeles County and the City of Malibu. Unlike the portion in Ventura County, much of the Los Angeles portion has been substantially subdivided. There are often significant resource concerns associated with development of these sites, including view shed impacts, slope stability, suitability of the site for septic tanks and impacts to sensitive resources. Many habitat concerns have been highlighted through the mapping of Significant Ecological Areas (SEAs), where development is prohibited. Due to the alteration of drainage associated with road construction, the Commission has tried to limit the further expansion of new roads and driveways. Due finally to the large number of small lots or lots with significant development constraints, the Commission also instituted a program of Transfer of Development Credits to encourage preservation of these sensitive areas as open space. Development levels through the area are based on a slope density formula in combination with Transfer of Development Credits.
The Malibu Land Use Plan (Malibu has a certified LUP, but the Coastal Commission continues to issue Coastal Development Permits since the area does not have a certified LCP) has a number of policies addressing land form alteration. Geology Reports must be prepared for any development proposed within potentially geological unstable areas. Hillside Management Procedures must be followed for sites with average slopes greater than 25%; there can be no grading or development-related clearing where slopes exceed 25%, except that driveways and utilities may be located on such slopes where there is no less environmentally damaging feasible alternative means of providing access to home sites located on slopes of less than 50%. All new development is reviewed to ensure that it will not generate increased run-off, debris and/or chemical pollution.
Areas of the Santa Monica Mountains have been subdivided into very small, urban scale parcels; however, it is expected that many of these sites will not build out due to slope or geologic conditions, septic limitations, development costs or other. A 1978 study found that an estimated 3,614 parcels would be considered "non-conforming" which could, theoretically be built out. The LUP proposes a mix of techniques, such as development allocation, fee acquisition, offers of tax delinquent parcels, lot consolidations, redevelopment and surplus land exchange to mitigate potential effects and reduce build out.
Los Angeles County requires grading permits for any activity involving excavation greater than 3' below ground level, fill greater than 3' above ground level or more than 20 cubic yards on any one lot, any fill that obstructs a drainage course, or any fill having a natural grade steeper than 3:1. Grading plans must be prepared by a registered civil engineer and if grading exceeds 1,000 cubic yards, a bond may be required. Fill slope design must follow the recommendations of Chapter 70 of the Uniform Building Code. In addition to a grading requirement, the County has developed a Brush Removal Ordinance which controls the removal of brush and vegetation from hillside and mountainous areas. Permits area required from the Department of Public Works for removal of vegetation from all slopes greater than 8%, unless clearing will be less than 2.5 acres in any 12 month period, or is for clearance on order of the Fire Department. The County has strict erosion control measures during the rainy season, including penalties for non-compliance. Leach fields cannot be built on slopes steeper than 30%; however, seepage pits have no such slope limitation and have been approved for use in fill slopes, bedrock shales and above landslide scarps.
The City of Manhattan Beach's Land Use Plan was approved recently by the Commission, with requirements for an aggressive response to dealing with storm water and non-point source pollution. The city initiated a storm water pollution abatement program and is developing codes and standards to implement the Good Housekeeping Requirements and Best Management Practices of the Santa Monica Bay Restoration Project Action Plan.
The City of Rancho Palos Verdes is perhaps best known for the Portuguese Bend landslide, an large active slide which has destroyed or damaged over 150 residences since it was activated in 1956. Total losses from the slide have exceeded 9 million dollars, making the City very conscious of the long-term problems which can occur from development on a landslide. As a result, Rancho Palos Verdes is one of the few local governments which requires detailed geologic reports and soils tests for thorough landslide identification prior to approval of any subdivision. In addition, Rancho Palos Verdes has a coastal setback line to minimize land form alteration along the coast.
Much of the Orange County coastal zone is developed. The two steep slope areas which are part of the coastal zone are the Irvine Ranch and Aliso Canyon, both in south Orange County. Within the Irvine Ranch, the downcoast two-thirds of the property has been protected through either purchase of the land for public recreation or dedication of the land for open space. This effort has protected these steep slope areas and associated habitats from disturbance. In Aliso Canyon, the Commission adopted a policy of preserving Wood Canyon and natural hillsides from the ridge top to the stream. In both situations, significant land holdings were available to establish both developable areas and protected areas.
In the areas of Orange County where development is allowed, erosion control plans are required for grading between October 15th and April 15th, and grading is prohibited if sedimentation cannot be controlled. Runoff controls have been incorporated into the plans for development on Irvine Ranch and in Aliso Canyon, with the intention of preventing long-term erosion from stream beds. In addition, Orange County has developed a handbook on Grading Fundamental Principles and Design Considerations which serves as a source of information for the development of alternative grading standards such as contour grading and the use of vegetation for site development and erosion control. Siltation, however, is viewed as a valuable source of beach quality material and the County supports efforts to insure that this material can reach the coast.
The San Diego County coast consists of a number of steep coastal bluffs and an extensive network of coastal lagoons. Most of the restrictions on steep slope development have attempted to address sedimentation of wetlands from upland development. In the Batiquitos watershed, the LCPs attempt to concentrate development on slopes less than 20%, or less than 10% for highly erodible soils; grading is prohibited between November 1st and March 31st. The County has mapped sensitive chaparral habitat for preservation and prohibits development throughout the county on slopes greater than 25%. This combination of slope and habitat protection has lead to a network of open space along the bluffs fronting the lagoons as well as preservation of significant riparian corridors.
Many of the urban areas in the County have developed maximum site densities based on the average slope of the site. Drainage from the site must be controlled to be equal to or less than pre-project levels. Soils studies are required for all subdivisions. The City of Oceanside has developed a Hillside Development Manual and Ordinance, allowing development on 20 to 40% slopes only if geologic stability is verified and the integrity of the slope of preserved. Runoff must be controlled on site or diverted to channels or culverts that provide energy dissipation to prevent erosion and siltation into rivers.
Over the years a number of reports and handbooks have been prepared on techniques to minimize or control runoff and sedimentation from various land use activities. In 1978, the State of California, Department of Conservation published an "Erosion and Sediment Control Handbook", prepared by Perry Amimoto. More recently, the Department of Forestry has published a Draft "Soil and Water Conservation Handbook: Water Quality Management for National Forest System Lands in California", the State of California Department of Transportation has published the "Storm Water Pollution Prevention Plan Handbook", and under the direction of the State Water Resources Control Board and other agencies in the Storm Water Task Force, Camp Dresser & McKee prepared the "State of California Storm Water Best Management Practice Handbooks".
Other states are also developing guidance and handbooks relating to slope management, for example "Slope Stabilization and Erosion Control using Vegetation: A Manual of Practice for Coastal Property Owners", prepared by Myers Biodynamics, Inc. for the State of Washington Department of Ecology. Likewise, many local governments have developed grading or slope stability guidance such as, "Grading: Fundamental Principles and Design Considerations" prepared by Center for Planning and Research for Orange County; "Groundwork: A Handbook for Erosion Control in North Coastal California", prepared by Liza Prunuske for the Marin County Resource Conservation District; "Hillside Residential Design Guidelines Manual", prepared by Gast and Hillmer for the City of San Raphael; "Single Family Residence Design Guidelines" prepared by a Guidelines Sub-Committee for the City of Santa Barbara; "Grading Guidelines", prepared by the County of Los Angeles, Department of Public Works; "Planning Guidelines: Landform Grading Manual", by the Department of City Planning, City of Los Angeles; or "Manual of Standards for Erosion and Sediment Control Measures", by the Association of Bay Area Governments.
For site development there are a number of requirements for site safety which often result in land form alteration. The three primary concerns are the Fire Department concerns about site access, it concern about fuel modification and the Health Department concern about septic systems and water supply. In areas prone to land slides, there is a fourth concern relating to general site stability. For efforts at minimizing land form alteration to be truly effective, the issues of access, fuel clearance, sites for septic systems and, if appropriate, the potential for landslides need to be addressed at the time that legal lots are being established. It is at the subdivision stage that areas can be determined to be undevelopable due to unstable slopes, unacceptable levels of grading for road access or excessive site clearing for fuel modification. More appropriately, it is at the subdivision stage that the developability of each lot should be demonstrated, since there are rarely clear definitions of what is either unacceptable or undevelopable.
Once a lot is legally subdivided, the general assumption is that the lot can be made safe for development through various engineering and technical efforts. At this point, planners are often faced with large quantities of non-discretionary grading necessary to safely develop a remote site or site on steep terrain. Regulatory agencies find it very difficult to deny permits for massive quantities of grading, if the grading is the minimum necessary to allow a property owner to develop their lot. As stated by William M. Brown, Physical Scientist for the U.S.G.S., for landslides, but equally applicable to other site development concerns, " Avoiding hazards can be done by selecting suitable sites for construction; this activity is one of intelligent foresight or, more commonly, is controlled by land-use zoning or building codes." (in "Coping With Landslide Hazards in California and the San Francisco bay Region", by William M. Brown III, Menlo Park, no date.)
Fire protection is one of the major concerns affecting the land form alteration requirements of new development, especially residential development. The two major factors in protecting a structure from fire are accessibility by fire equipment and distance from flammable material. Following the 1991 fires in North East Washington State, the National Wildland/Urban Interface Fire Protection Initiative found, among others factors, that, "roadways and restricted driveways to homes limited response and operational choices of fire fighters. The terrain features roads that twisted to follow the hillsides and ridges." (in "Fire Storm '91: Case Study") The study also found that, " The most consistent factor associated with structure loss of the homes studied in these fires was the distance of the homes from adjacent combustible vegetation. In most cases, the proximity of homes to flammable fuels was 20 feet or less." Structural features too can be a factor, where the study found that, "wood exterior construction and open wood decks, porches, or balconies also provided a ready source of easily ignitable fuel. Desks, porches and balconies did serve as an easy path for burning vegetation to reach structures ..... (becoming) even more hazardous when the areas underneath them were used to store combustibles such as firewood."
Most local governments have road requirements which are established to insure that the available fire equipment can access a possible fire site. For the County of Los Angeles, for example, the Fire Code Standard for Private Access Roads and Driveways for Single Family Dwellings requires that, "access roads must be provided which will support Fire Department apparatus". The code goes on to discuss requirements for grade, width, curve radii, paving, drainage, turnouts, etc. Similarly most local and county governments have requirements in low density development areas for fuel modification or fuel clearing to provide a safety buffer between the structure and combustible material.
Once the need for fire access roads or vegetation clearing has been established and the extent of land form alteration from these actions has been found to be excessive, there are some opportunities to modify the access or clearing requirements to reduce the level of impact. Most fire equipment is custom designed, allowing communities which have a significant amount of hillside development to specific design options which allow access along windy hillside roads. In the same way that developers often transfer flat land designs to hillside and steep slope development, many developed hillside fire prevention efforts center around using flat land equipment, requiring the site to adapt to the available technology. Rather than a classic hook and ladder truck, hillside fire fighting efforts may rely more on equipment that can be mounted on pick-up trucks, with hydrants and other supporting equipment provided as part of the hillside development. For example, most of the fire vehicles used in Marin County are four-wheel drive trucks which can negotiate the narrow steep roads that provide access to hillside development. For areas without hydrants, water is supplied by water towers or tenders mounted on four-wheel drive vehicles. Hillside fire fighting may also rely strongly on aerial equipment. Such equipment changes, if possible, would limit road access to a size appropriate for the ingress and egress requirements of the residents.
When equipment modifications area not feasible or reasonable, some modification to the standard access may allow for some reduction in the extent of land form alteration. Most fire access requirements allow a one lane road with turnouts to be substituted for a two lane access road. This can often reduce the total grading required for access. Alternatively, a split road could reduce total land form alteration by using two small road cuts rather than one large road cut. Bridges, too can be used to span areas which would otherwise require significant cut and fill to develop an access route or to maintain a gentle grade. A variety of access options should be examined if the initial access proposal would lead to excessive land form alteration.
Fuel clearing is often viewed as a major factor in land form alteration, but often can be accomplished without causing significant impacts. Ideally, fuel clearing will result not in a barren swathe surrounding the structures to be protected, but in a reduction in combustible vegetation and in a replacement of high hazard fuel types with more fire-resistant vegetation. Much clearing can be done manually, eliminating the need for heavy equipment or vehicle access in the area surrounding the structures. Clearing can be done during times of the year when the clearing activities are least likely to trigger erosion and sedimentation. Finally, since utility corridors and proximity of power lines to flammable vegetation to are often identified as the causes of non-arson fires, the clearance requirements for utilities needs to be considered in locating utilities. In some cases, underground utilities may be reasonable options when the issues of vegetation clearing and fire protection are considered.
Septic systems with leach fields require fairly gently sloping land with granular soils to be effective. Most local health departments are familiar with the slope and soil requirements for safe septic operation. In addition to testing that the soils on site will percolate, it is normal for leach fields to be limited to slopes less than 30%. In some locations this limitation can effectively prohibit development on a lot; however, some areas such as Los Angeles county allow seepage pits to be used if leach fields cannot be established. Recent water quality standards which encourage greater use of on-site disposal systems may expand the use of such systems. For a multi-unit subdivision, a community-wide treatment plant or septic system may replace individual leach fields and allow a reduction in site disturbance.
While some restriction on site modification can be relaxed to accommodate development, restriction on septic design are usually taken as absolute, with no relaxation of requirements possible. However, if a lot has an area suitable for a septic system, this may not only dictate developability but also the location of development. Site disturbance would include not only the disturbance for the structure, but also disturbance for the septic system and necessary construction equipment. A second issue with septic systems or seepage pits in steep terrain is that these systems function by carrying waste water into the ground to be cleaned as it migrates downslope. In areas with landslide potential, slides can be activated by increases in groundwater. Complete analysis of a site must consider all the constraints which may occur. Although a single septic system may not be enough to raise concern about the activation of a landslide, the cumulative impact from ten or twenty lots, with septic systems, irrigated landscaping and other small sources of groundwater, may pose a serious concern.
In steep coastal areas with the potential for landslides, landslide remediation can result in significant alteration of natural land forms. When landslide activity has played a major role in developing the dominant land forms, efforts to mitigation landslides can have a dramatic effect on the region. In addition to changing the visual character of the area, large engineered slopes can change to natural runoff and drainage characteristics since most efforts to assure slope stability are concerned with preventing water from percolating into the engineered slope. Ignoring or improperly mitigating landslides can also have a dramatic effect; in California between 1973 and 1983, it has been estimated that one hundred million dollars in damage occurred annually due to landslides (adapted from Brabb, 1984; presented in Federal Emergency Management Agency, "Landslide Reduction: A Guide for State and Local Government Planning", August 1989).
In areas with high landslide potential, the best way to minimize alteration of natural land forms is often to locate and avoid all slide hazards. (While avoidance may be the best way to minimize land form alteration and the expense of landslide remediation, property owners have been found liable for the impacts from slides, even on undeveloped property which encourages property owners to consider remediation even when avoidance is possible.) Numerous papers and books have been published on landslide mitigation efforts, descriptions of various techniques, comparisons between various techniques for specific slide types, and other landslide mitigation topics. In almost all cases, land slide mitigation requires land form alteration, either to remove and recompact the slide, or to access the area to install stabilizing to retaining efforts. The Commission staff report, "Overview of Engineering Techniques to Reduce Grading," describes many of the common techniques to stabilize landslides and discusses options for reducing the amount of land form alteration; however, only the option of avoidance eliminates the need for some amount of land form alteration.
When the City of Manhattan Beach was working to amend its Land Use Plan to address storm water pollution abatement, one of the findings was, "In the process it was found that a number of ordinances already exist on the books that cover most of the original concerns [relating to illegal dumping to catch basins and the storm drain system]. It was determined that those significant codes contain strong enforcement capabilities and that the present city staff needs to be educated and made aware of those existing codes ..... The program is to develop codes and building standards ......., educate staff, eliminate potential loopholes within the existing code sections ..... ." Similarly, it seems that for land form alteration, there are available state regulations, interpretive guidelines, local policies and ordinances, and a broad range of handbooks and technical guidance to promote land development efforts which minimize land form alteration. There are also established codes and practices for the various efforts which tend to exacerbate efforts to reduce land form alteration, such as requirements for fire access, health and safety requirements for septic systems or established practices for land slide remediation.
Despite this vast array of information, the concerns for land form alteration often are either overlooked or relaxed in the face of detailed technical requirements. The review of planning material relating to land form alteration shows an understanding on the concerns for land form alteration and a broad range of regulations and guidelines to safeguard against both excessive land form alteration and the resultant problems which can occur from any alteration activity. However, these concerns for land form alteration are often relaxed to comply with the absolute health and safety requirements for septic design, road widths or stability of landslide remediation. Development activities can often accommodate all planning, health, safety and stability concerns, but all the concerns must be examined early in the project design phase, and all concerns need to be approached with some flexibility and opportunity for alternatives or modifications.
ENDNOTES
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