There are few if any slopes in the City of Malibu that truly can be said to be "mountainous" which means, in the abstract, an area of considerable extent with slopes that are especially high and steep. In this regard, mountainous terrain in the western Santa Monica Mountains lies only within the unincorporated areas of Los Angeles, and Ventura counties, and even there, they don't hold a candle to the mountainous terrains of the San Gabriels and the San Bernardinos. Nevertheless, of Malibu's reported 19.9 square miles of land area, roughly 10 square miles is hillside or mountainous terrain. As pressure for development increases, questions regarding hillside development become more important.

The use of hillside areas in Malibu for residential development is limited essentially in two ways. One is the environmental aspects of planning as reflected in the necessity to conform to the Local Coastal Program (LCP) and particularly its Local Implementation Plan (LIP). The other is the physical aspect particularly in terms of its topography and its geology.

LIP RATIONALE FOR HILLSIDE DEVELOPMENT

According to the Malibu's LCP, (LIP Ch. 8) - 8.1 grading should be kept to a minimum in order to minimize the "... visual and resource impacts of grading and landform alteration." To do this:

Development shall be planned to fit the topography, soils, geology, hydrology, and other conditions existing on the site so that grading is kept to an absolute minimum (8.3).

The LIP limitations present the issue of aesthetics: to whom is the decision left as to what is or is not aesthetically acceptable? Inherent in the LIP is the underlying conceptual idea concerning hillside development in Malibu, seems to be that attributed to architect Frank Lloyd Wright, that a structure should be "organic" with its environment. In other words, a hillside structure should somehow blend with the topography, vegetation, and perhaps other local conditions. It's a nice idea, but Frank is no longer around. So how do we decide aesthetic-wise? In Malibu, the LIP codification of Wright's organic idea is essentially limited to requiring a minimum amount of grading.

LIP LIMITATIONS ON HILLSIDE DEVELOPMENT

LIP hillside design criteria are used to enforce aesthetic conceptual planning in Malibu rather than their normal use as a matter of safety. This is done by certain limitations on grading. Among them are: [i] a maximum of 1,000 cubic yards of exported earth materials or import of earth material for fill, or some combination of the two (LIP Sec. 8.3, B, a-d); [ii] a maximum single retaining wall height of 6 feet and no combination walls higher than 12 feet with 3 feet or more between them (LIP Sec, 8.3C); [iii] a maximum gradient of 3:1 for any cut or fill slope to serve as a site for structures or yards (LIP Sec. 8.3D); and [iv] where feasible, the elimination of flat building sites in favor of split-level structures notched into slopes (LIP Sec. 8.3 E4).

Limitations [i] - [ii] are strict design standards whereas limitation [iv] is a subjective design principle likely to raise an issue of feasibility. The definition of "feasible" needs qualification. In practice, it ranges from "possible" to "economically practical," and is a sure source of conflict in interpretation, simply because both the single cut-and-fill pad may be more or less desirable on the part of the developer. The idea is, of course, that a split-level structure more or less draped down a slope is visually more pleasing to someone, some would say "big brother," than is a simple cut-and-fill level pad. In any event, with regard to steeper slopes possible for practical development, say those with slopes in the range of 25 to 30 degrees, the maximum building pad width without resorting to adjacent down-slope fill is 28.5 to 20.8 feet, respectively because of limitation [ii].

NORMAL PHYSICAL LIMITATIONS ON HILLSIDE DEVELOPMENT

Exclusive of aesthetics, the two basic problems of hillside development in Malibu or anywhere else for that matter, are those of access and slope stability. The concern regarding access is whether the roadway meets Los Angeles County Fire Department standards. For years these have been: [i] a 20-foot wide roadway; [ii] a maximum roadway gradient of 20 percent; and [iii] a so-called "hammerhead" area for turning Fire Department vehicles. This may introduce the necessity for special grading. In the past, sites where access for Fire Department vehicles is not practical, an interior sprinkler system and an adequate supply of stored water has been required. However, it is best to consult with Fire Department representative at the County offices in the Malibu Civic Center for current specific requirements.

The problem of slope stability in Malibu is the same, in principle, as that in most California jurisdictions. It is simply that any slope that might fail as a landslide thereby adversely affecting either the property proposed for development, or a neighboring property, must be shown to have a safety factor of at least 1.5 before a grading permit or a building permit would be issued for that property. In this regard, either one or more natural slopes or one or more proposed slopes might be of concern, but in any case, shear strengths of the materials of which the slope is composed must be determined. Such determinations might be made in the laboratory from collected samples of those materials, which is costly, or from reasonable estimates of shear strength. It is not unheard of that sampling and testing has been required by the City geotechnical staff where the project geotechnical engineer, supported by the project engineering geologist, considers laboratory testing unnecessary.

CONCLUSION

It should be understood that the development of hillside areas in Malibu is strongly controlled by an arbitrary and overriding standard of aesthetics rather than safety or personal concerns. The prospective developer is well advised to become familiar the LUP as the fundamental controlling criterion in considering the manner in which property must be designed and hence its value.

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