MARCH 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.
Since its inception, the California Coastal Commission has reviewed thousands of applications for Coastal Development Permits for construction along the coast for, among others, homes, commercial and industrial buildings, subdivisions, highways, shopping centers, and sports complexes. While many of these permits involve small amounts of land form alteration, such as clearing a small area for a driveway, excavating soil for a basement, grading a level site for a foundation, the Commission also regularly reviews development projects which propose large amounts of grading, alteration of natural drainage and vast areas of disturbance. The Commission is charged directly with concern for land form alteration through Section 30251 of the Coastal Act. The Commission often takes an expansive view of alteration of natural land forms, but for this report, the term only encompasses vegetation clearing and all forms of earth moving, such as cut, fill, removal and recompaction; it does not extend to placing rip-rap, retaining walls, buildings or other structures.
In addition to the concern for alteration of natural land forms, the Commission, through other Sections of the Coastal Act, is mandated to minimize streambed alteration, and to protect water quality, environmentally sensitive habitat areas, and other resources. Since land form alteration often can lead to or result in stream bed alteration, sedimentation and degradation of water quality, and disturbance of sensitive habitats, minimizing land form alteration can result in minimizing a broad range of environmental impacts.
While the concern for the minimizing the alteration of natural land forms is compatible with many other environmental concerns, it can be at odds with concerns about fire safety, adequate access, site stability or design needs (such as providing flat areas for specific building designs, tennis courts, pools, riding facilities, etc.). In addition, since it is relatively inexpensive to move dirt from one part of a site to another, the preferred economic option is often to reconfigure the site to the project, rather than design the project to fit the site and minimize grading.
This report discusses:
- the basis for Commission concern about alteration of natural land forms,
- the environmental effects associated with land form alteration, and
- the potential conflicts between minimizing the alteration of natural land forms and other issues of land use or public safety concerns.
This report is the first of several reports which examines the policy aspects of land form alteration. The second report will deal with regulatory policies and processes and explore, in more detail, the conflicts and coordination between various policies that affect land form alteration. The final product will be policy guidance for land form alteration, with workshops on this effort.
The 1976 Coastal Act established the California Coastal Commission's role in providing for the conservation and orderly development of California's 1,100 mile coastline. The Coastal Act's policies guide coastal zone conservation and development decisions to protect California's coastal resources and provide for their prudent use. Two policies specifically address concerns for alteration of land forms and natural stream beds. Section 30251 states:
The scenic and visual qualities of coastal areas shall be considered and protected as a resource of public importance. Permitted development shall be sited and designed to protect views to and along the ocean and scenic coastal areas, to minimize the alteration of natural land forms, to be visually compatible with the character of surrounding areas, and, where feasible, to restore and enhance visual quality to visually degraded areas. (Emphasis added)
Section 30231 states that:
The biological productivity and the quality of coastal waters, streams, wetlands, estuaries, and lakes appropriate to maintain optimum populations of marine organisms and for the protection of human health shall be maintained and, where feasible, restored through, among other means, minimizing adverse effects of waste water discharges and entrainment, controlling runoff, preventing depletion of ground water supplies and substantial interference with surface water flow, encouraging waste water reclamation, maintaining natural vegetation buffer areas that protect riparian habitats, and minimizing alteration of natural streams. (Emphasis added)
Both of these sections direct the Commission to address effects to land forms and drainage in its review of projects. In 1975 the California Coastal Zone Conservation Commissions prepared and issued the California Coastal Plan, a predecessor to the Coastal Act of 1976. This document discusses many of the coastal problems and issues and recommended policies which often formed the basis for Sections of the Coastal Act. The Coastal Plan found that:
The soils and minerals of the coastal zone are irreplaceable resources of California. The Plan requires that local building and grading ordinances include effective measures to control erosion. (California Coastal Plan, 1975, page 7)
Although the language of this policy was not incorporated into the Coastal Act, much of the underlying intent can be found throughout the Act.
The Commission regularly reviews applications for large amounts of grading within the coastal zone. For example, in 1990, two applications were received which together totaled over 5.3 million cubic yards of cut and 4.8 million cubic yards of fill. These two projects were for large subdivisions and both were denied. As proposed, these projects would have cleared extensive areas of land, redirected numerous small drainages and rivulets, and dramatically altered the existing character of the community for which they were proposed. In the same year, the Commission reviewed and approved an emergency permit for a section of Highway 1 which was closed by a landslide and approximately 1 million cubic yards of material was moved to reconstruct 800 feet of highway. These are but three of a large number of projects involving massive grading and land form alteration, proposed in steep, undeveloped and highly scenic areas which have been proposed all along the coast.
In the winter of 1991/1992 and again in the winter of 1992/1993, major coastal storms hit southern California. Following these storms, Commission staff viewed first-hand the erosion, runoff, and water quality degradation that can occur from grading. Weather forecasts warned many property owners of the storms, giving them time to protect exposed areas with temporary erosion control devices. Despite these preparations, many construction sites showed evidence of gullying and erosion; some roads and major highways were closed temporarily due to mud and debris flows; sediments that had been deposited periodically in streambeds were carried by flood flows far downstream, into coastal wetlands or onto coastal beaches. The damage that occurred was not solely due to erosion from site grading; however, the numerous grading projects throughout the region clearly contributed to the total problem.
Through the permitting process, the Commission and staff can often work with applicants to reduce the amount of grading proposed for projects, and insure that impacts from grading are reduced by erosion and runoff controls. There are many situations where grading amounts have been reduced severalfold by careful examination of the type and extent of proposed land form alteration. For example, a project proposed 129 thousand cubic yards of grading for a 5 lot subdivision. After working with staff, the applicant was able to reduce the amount of grading to under 25 thousand cubic yards of cut and fill, and develop a project which received approval from the Commission.
Usually, these efforts to reduce grading during the permit process are undertaken on a case-by-case basis. In 1992, the Commission studied the California Coastal Management Program (CCMP) and found, among others, that the current implementation of CCMP hazards policies fails to consistently discourage excessive grading. As stated in the Coastal Hazards Strategy, submitted to the Office of Ocean and Coastal Resources Management,
Coastal landform alteration is a serious Coastal hazard problem in two respects. First, inadequate identification and assessment of geologic hazards in the coastal zone is often a precursor to excessive or unnecessary grading in development projects. This grading, in turn, leads to adverse cumulative resource impacts, including: increased erosion, siltation, and shifts in depositional areas; changes in sedimentation rates and patterns resulting in contaminated surface and groundwater systems and public drinking water; visual degradation in mountainous areas and along coastal bluffs; and the disturbance of the stability of environmentally sensitive habitats in and around excessively graded areas. Second, poorly implemented grading, whether it is excessive or not, can lead to secondary threats to life and property due to increased erosion and landsliding, particularly under extreme circumstances such as the recent storms and flooding in Southern California.
Due to the Commission's familiarity with these concerns relating to grading and the realization that these concerns are not now being addressed adequately, the Commission proposed to report on priority land form alteration policy concerns, to report on the CCMP coastal hazards regulatory process, and to draft policy guidance on the alteration of natural land forms. This report is the first step in the Commission's efforts, a summary of land form alteration policy concerns.
When land is graded, there can be impacts not only to the graded land, but impacts to adjacent properties, downstream lands and the flora and fauna which depend on the environmental quality of these lands. The impacts due to land form alteration can vary from project to project, but there are a number of common concerns which arise from most grading projects, regardless of the project specifics. Perhaps the best way to illustrate the various concerns of the Commission with land form alteration is to discuss some of the various steps of a typical grading project.
Grading Is Used For Site Stability And Design: Most often, grading is done to make land a safer or more acceptable building area than existed previously. Many geologic hazards, such a small landslides or poorly consolidated soils, can be corrected by grading, either excavating the slide or poorly consolidated soil or replacing it with recompacted soil. If a project design requires a flat pad for siting a building, tennis court, road, riding stable, etc., and the property is not naturally flat, the required pads can be created by cutting material from an area with excess soil or elevation and moving it to low areas which can be raised. Much of this grading can often be avoided, and later documents will address ways to avoid or reduce grading, but, when grading is done, it is usually done for these two reasons -- improving the geologic stability of the site or creating buildable area in the site.
Access To Start Grading Will Disturb The Site: The first step in the grading process is getting the grading equipment to the portion of the property which needs to be graded. Since most grading is undertaken to make a site more suitable for human use, usually, this access can serve as permanent access to the property after the grading is finished. Once it is decided to alter a portion of a site, it will usually be necessary to develop a roadway from an existing road system to that portion of the site.
Initial Site Clearing Will Remove Vegetation And Habitat: The first and often most obvious effect from grading is that the area to be graded and the access to the area will be stripped of vegetation. This step alone can cause visual scars in scenic areas and change the visual character of the area, and is a concern of the Commission through Section 30251. It also will reduce the amount of vegetation cover and habitat for native, and in some cases environmentally sensitive species (Section 30240). Once the vegetative cover is removed, if the soil is exposed to surface water, through rainfall or runoff from other areas, the soil can be eroded and carried off site, causing excess sedimentation and possibly water quality degradation if this material gets into a stream, creek, wetland estuary or the open ocean (Sections 30231, 30233 and 30236).
Cut And Fill Can Disturb Drainage Patterns: In a normal grading operation, once vegetation is removed, excavation will begin. If the intent is to simply excavate an area to provide a buildable site, and if none of the excavated area is to be revegetated, all the material can be removed and carried off site for disposal or reuse. The effects from this action will be the loss of habitat from the cleared area and possible changes to surface drainage and rainfall infiltration. If, for example, a building pad is notched into a hillside, the surface runoff which previously flowed down the hill and across the building pad, will be interrupted by the building and will be redirected around the building.
Disposal Of Excess Material Can Increase Surface Disturbance: Often, even if the project only requires removal of material (or a cut), the excess material will be dispersed on site to avoid transportation costs and the impacts associated with hauling dirt. On-site disposal, however, can cause site impacts by disturbing additional area and possibly covering productive habitat with the excess dirt, creating a new source of sediment and possibly causing water quality degradation if the excess material is not protected from drainage and runoff.
Stockpiling Of Topsoil For Revegetation Can Add To Eroded Areas: If it is necessary to clear more area than will ultimately be covered by buildings, for example, when a landslide along a roadway is being stabilized or when material is removed from one area to provide an elevated building pad in another part of the property, it is normal to separate the top soil from the underlying, less productive soils and save the topsoil for reuse. To do this, topsoil will be scraped from the exposed area and it will be stockpiled elsewhere on the site to be reused during site restoration. For projects where the topsoil is stockpiled, the stockpile itself can require a cleared area as well as cleared access between the grading sites and the stockpile site. In addition to the loss of vegetative cover and habitat, the stockpile must be protected from surface erosion, just like all other exposed portions of the site or it can cause sedimentation and possible water quality degradation. If the topsoil is not stockpiled, the additional surface disturbance and possible sedimentation from the stockpile can be avoided, but it is often much more difficult to revegetate a site when topsoil is not available.
Engineered Slopes Different From Natural Slopes: In nature, soil can often achieve a rather steep slope, due to natural cementation and compression during formation and surface water can penetrate into the soil or form irregular drainage patterns. Once an area is "worked" or engineered, however, there are often codes or standards which dictate slopes and drainage configurations necessary to maintain a safe slope. These codes or standards have been developed from years of experience and observation of what seems to be effective ways to create safe slopes; however, strict adherence to these standards can lead to a very orderly and unnatural-looking landscape, with gentle 2:1 slopes, regularly spaced terraces and down drains, and all runoff diverted into controlled channels. In areas with steep slopes and dramatic relief, this can lead to an extreme change in the visual character of an area. Vegetation that had existed in the area previously may or may not be able to reestablish on these designed slopes even if the top soil is stockpiled. Following extensive grading it can take several years for the site to fully revegetate, assuming that full revegetation is possible. All the time that the site is being revegetated, portions of the site will be exposed to surface runoff and erosion, causing sedimentation and possible water quality degradation well past the time that the site was graded and that these effects were anticipated.
Engineered Slopes Can Alter Drainage Patterns: The original drainage from this site would have been dispersed as sheet flow or small concentrations of runoff into gullies and rivulets, with some infiltration of surface water through the soil. The overland and near surface flows would have supported surface vegetation and riparian habitat. Surface drainage from an engineered slope will be concentrated in terrace drains and down drains. Subsurface flows are often collected too, and all water from the site is often discharged at a few concentrated points. It is often necessary to irrigate engineered slopes to support the revegetation efforts since much of the rain and subsurface water available to the site is carried away from the slopes into controlled drainage channels. Concentrated discharge from these drainage channels can both cause downstream scour and reduce the extent of riparian habitat which had relied previously on this unconcentrated, overland flow.
Grading Has Cumulative Impacts Due To Quantity And Size Of Projects: This is not a complete picture of the possible effects from grading, but a general overview of some of the more common effects from grading. It is but a small example of the interconnectedness of our environment and how action in one area can have profound effects in other areas. In addition, some or all of these effects can be expected from every grading project which is undertaken. Since grading is such a standard part of site development, these impacts occur throughout most watersheds, wherever there is construction activity. The concern is not only for the one big project which has extensive impacts, but also for the vast number of small projects which cumulatively contribute to drastic visual changes, loss of habitat, sedimentation and water quality impacts.
Steep Slopes Can Accentuate Grading Needs And Impacts: Development in steep slope areas can often require extensive land form alteration to site structures safely. Steep slope areas often contain geologic instabilities that must be mitigated to make the site safe. Even if the site is stable, many of the components of a development, such as roads, utilities, and septic, have requirements for flat or gently graded areas, which are independent of the local topography. Since steep slope areas are often visually dramatic and since it is much more difficult to control erosion and runoff from a steep slope, grading or land form alteration in a steep slope area can have significantly more impacts than the same amount of grading or land form alteration in a more gently rolling area.
Quantification Of Grading Impacts Is Difficult: There are a number of ways to quantify grading and grading related impacts. The area extent of disturbance provides information on the amount of vegetation and habitat that will be removed, and is easy to quantify. The volume of cut and fill can provide information on the extent of grading and amount of soil that will be moved, and also can be determined. The amount of erosion and sedimentation from a graded site is difficult to quantify and will depend significantly on rainfall intensity, erosion control efforts, site characteristics and management, etc. The extent of exposed land and the amount of soil being moved can provide some indication of the potential for significant erosion and runoff. Many efforts at predicting soil loss, erosion or sedimentation base their efforts on the amount of exposed land or average slope of the site. In general studies of sedimentation, the York County Soil Conservation District found that acre for acre, construction sites can produce 5 to 500 times the sediment of developed lands and 10 to 20 times the sediment of agricultural lands, with estimated sedimentation rates ranging from 36.5 to 1,000 tons/acre/year (York County Soil Conservation, 1990 ). From a general review of the literature and discussion with erosion control specialists, this possible range of sedimentation rates is realistic, and it is difficult is predict accurate sedimentation rates for a specific development project.
Added Uncertainty Exists In Predicting Grading Impacts On The West: California and other western states have precipitation characteristics which can lead to extreme variations in erosion and sedimentation rates. In most of California, rain tends to be very seasonal and average rainfall amounts have little significance. For example, an area may have an average annual rainfall of 20 inches, and in much of the country the year to year rainfalls may vary from 15 inches to 25 inches per year. However, California can have several years of drought followed by rain, and the 20 inch rainfall average can occur as 5 inches per year for 4 drought years and 80 inches of rain for the rainy year (for a total of 100 inches over a 5 year period, or 20 inches per year). Efforts to predict sedimentation rates for a specific site in California are hampered greatly by the uncertainty of future rainfall intensities. A site may have minimal runoff for a number of years, since there is little if any rainfall, followed by extensive erosion during a brief period of intense rainfall.
Rainfall Variability Can Complicate Site Protection: Coupled with the difficulty in predicting sedimentation rates, due to the great variability in rainfall, is the difficulty in determining the level of site protection that is necessary to minimize erosion and runoff. Protective efforts which may have been adequate for several years of drought may be ineffective during a rainy year. Rainfall variability can also hamper revegetation efforts. During drought years, irrigation will likely be necessary, but during a rainy year, the rains may be sufficiently intense that poorly-established vegetation may be washed away, adding to the material that can be carried into stream beds and drainage courses. During periods of drought, there is the added problem of wind erosion of bare, unvegetated sites, and the difficulties of providing adequate water to quickly establish new vegetation.
While it is possible to mitigate many of the possible effects from grading through innovative grading or soil preparation techniques (some of which are discussed in the Commission's report on Techniques to Minimize Grading in Land Development within the California Coastal Zone, Draft Report), or to control erosion and scour through careful site management (discussed in the U.S. Environmental Protection Agency's Guidance Specifying Management Measures for Sources of Nonpoint Pollution in Coastal Waters, in preparation), the best way to minimize these impacts is through the source -- the grading itself. Most of the Coastal Act policies which relate directly or indirectly to land form alteration support the approach of impact avoidance as a preferred approach and mitigation of the impacts only when they prove to be unavoidable. Due to the extent of possible water quality and habitat impacts which can result from grading actions, the Commission views the reduction of grading as the first opportunity to address all these concerns, rather than attempting a piecemeal, bandage approach to correct or reduce the after effects of grading.
Land development can cause a number of changes or modifications to both the developed area and its surroundings. Just as there are a number of impacts which can occur from land form alteration, there are also a number of factors which can influence the type and extent of land form alteration that is needed.
Land form alteration occurs for two major purposes -- to remove or mitigate a geologic hazard, or to create a more buildable site. Efforts to reduce the amount of land form alteration must recognize the underlying reason for the grading. Much of the grading for geologic hazards can be reduced by avoiding the hazard or by working with an engineering geologist or project engineer to develop site-specific stabilization techniques. Efforts to minimize the amount of grading for a buildable site would rely more on modifications to the project design or scale of development. In many steep slope areas, these two factors are intertwined and may be difficult to separate.
As mentioned earlier, some of the components of a development project have site requirements which are fairly independent of the local topography. For example, water lines need to be rather straight and pumping facilities will be needed to lift water to the top of a hill. Most development sites must provide some type of sewer or septic system and again installation of these systems will require some amount of land disturbance to either lay sewer lines or construct an on-site waste disposal system. These systems, too, will be sized to serve the projected demand from the project and typically the site is modified to accommodate the needed utilities.
The biggest disturbance to many sites can come from the required road access. Most local governments have developed standards for roadway widths, grades, curve dimensions, etc. which are intended to provide safe access to the site for regular vehicles and emergency equipment, but significant site alteration is often required to meet these standards. Some of these standards can be modified for steep slope development, and innovative access designs or safety equipment may reduce the amounts of grading that would be required; nevertheless, safety equipment, such as fire engines, must be able to access sites which are developed for human occupancy, and people must be able to escape an area if the primary access route is blocked. As with many concerns, this one has two mutually compatible approaches -- to carefully plan and consider access early in the planning process and to explore ways to design roads and safety equipment to minimize grading requirements.
There are a number of agencies which review a land development project for specific concerns, such as fire abatement and access for fire equipment, air quality impacts from construction equipment, noise and traffic impacts, and water quality concerns, there is no agency which has as its primary responsibility the minimization of grading. Nor is there an identified point in the project development and review process where land form alteration is considered consistently. While the State Water Resources Control Board requires that all projects with more than 5 acres of grading obtain a National Pollution Discharge Elimination Permit (NPDES), smaller projects do not receive such scrutiny. Most local governments review grading plans, but the reviews normally address the effectiveness and safety of the proposed grading, and do not address the quantities of grading. In an effort to comply with the concerns of these numerous agencies, the concern for land form alteration can, at times, be overlooked or minimized.
Land form alteration have been identified in the Coastal Act as an issue to be considered in the review of development projects. This concern stems from an interest in protecting the general character and visual quality of coastal areas. In addition to the direct concern for this alteration, there are concerns about the resultant effects from such alteration, including but not limited to, erosion and siltation, habitat loss, water quality degradation and long term alteration of drainage patterns and surface water flows. Impacts from land form alteration can occur from the first efforts to clear vegetation and continue well after the bulldozers have left the site and all the grading work has been finished.
While the best approach to minimizing land form alteration may be to avoid all grading or vegetation clearing, this is not always possible or reasonable. Once a site has been subdivided and determined to be developable, there are a number of necessary support items, in addition to the development itself, that will be required. Roadways, utility installations, fire breaks, slope stability and others may all require some land form alteration. Policies to minimize land form alteration can conflict with policies to provide safe access, water supplies, adequate septic service and a buildable site. While most of these concerns are addressed by specific agencies and covered by various codes and standards for development, there is no one agency or review point which addresses land form alteration.
In summary,
California Coastal Commission, 1993, California Coastal Act of 1977.
California Coastal Commission, 1992, "Techniques to Minimize Grading in Land Development within the California Coastal Zone", Unpublished Draft Report.
California Coastal Commission, 1981. "Statewide Interpretive Guidelines".
County of Los Angeles, Fire Department, "General Access Guide for Single Family Residence" and "Private All-Weather Access Standards", from L.A. County Fire Code Standards.
Edil, T.B., and L.E. Vallejo, 1980. "Mechanics of Coastal Landslides and the Influence of Slope Parameters", Engineering Geology, 16, pp. 83-96.
International Conference of Building Officials, 1988. Uniform Building Code, Whittier, CA.
International Erosion Control Association, IECA Report, Steamboat Springs, CO.
Kerr, Sinclair, 1987. "Legal Issues of Landslides: An Outline", prepared for the course entitled, Slope Stability and Landslides.
Plant, Nathaniel and Gary Griggs, 1990. "Coastal Landslides Caused by the October 17, 1989 Earthquake Santa Cruz, California", California Geology, Vol. 43, No. 4, pp. 74-84.
San Francisco Estuary Project, 1992. "State of the Estuary: A Report on Conditions and Problems in the San Francisco Bay/Sacramento-San Joaquin Delta Estuary" , Oakland, CA.
San Francisco Estuary Project, 1992. "Draft Comprehensive Conservation and Management Plan for the Bay and Delta", San Francisco, CA.
Scullin, C.M., 1983. Excavation and Grading Code Administration, Inspection and Enforcement, Prentice-Hall, N.J.
State of California, Department of Conservation, 1981. Erosion and Sediment Control Handbook, Sacramento, CA.
State of California, Department of Conservation, (Perry Amimoto, ed.) 1989. Erosion and Sediment Control Handbook, Sacramento, CA.
State of California, Department of Transportation, Division of New Technology, Materials and Research, 1992. "Storm Water Pollution Prevention Plan Handbook", Sacramento.
State of California, Division of Mines and Geology, "Guidelines for Standards of Practice of Geology in California, CDMG Note #37, 43, 44, 46, 47, 48, 49". Sacramento.
State of California, Division of Occupational Safety and Health, 1992. "Excavation Trenches Earthwork, Construction Safety Orders, Sections 1504, 1539-1547, Title 8", California Code of Regulations.
Sydnor, Robert, et al., 1990. "Coastal Bluff Landslides in Santa Cruz County Resulting from the Loma Prieta Earthquake of 17 October 1989" California Division of Mines and Geology, Special Publication #104.
U.S. Environmental Protection Agency, 1992, "EPA Guidance Specifying Management Measures for Sources of Nonpoint Pollution in Coastal Waters", Unpublished Work Group Working Paper.
U.S. Environmental Protection Agency, Office of Water, 1989. "Saving Bays and Estuaries: A Primer for Establishing and Managing Estuary Projects", Washington, D.C.
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