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Stability of Slopes


A “slope” could be the inclined side of a hill (a natural slope) or the side of a man-made earth or stone structure as a dam or an embankment (an artificial slope). The failure (collapse) of the material (soil or rock) beneath a slope is called a “slide”. A slide can be caused by the gradual deterioration of the soil beneath the slope, or the increase of the pressure of the water in the soil after a heavy rain, or the shock from an earthquake, or for no apparent reason. A slide can happen slowly or suddenly.

The paramount factor in the cause of a slide is the kind (the quality or the properties) of the soil beneath the slope. The soil of a natural slope has a rather “chaotic” structure with infinitely varying properties. A man-made, artificial embankment, etc, constructed by compacting previously selected soil in layers of a few inches thick, has more or less known properties and is easier to deal with, compared to a natural slope. So, given the haphazard parameters entering the problem of slides, man is faced with the extremely difficult task of finding how slide-prone, or how stable, is a slope, especially a slope covered with houses. As with quakes, so with slides the media presume that the people who deal with slides are the geologists. In reality, it is civil engineers, specialized in the complex subject (or “art”) of soil mechanics, the ones that study the problem of slides, that is the “stability of slopes”. One of the foremost authorities in the world on the stability of slopes, Professor Emeritus Ralph Peck of the University of Illinois writes:

“Because of the extraordinary variety of factors and processes that may lead to slides, the conditions for the stability of slopes usually defy theoretical analysis.” Yet, civil engineers with expertise in soil mechanics and experience in the field can have an educated opinion (on the side of safety) on how slide-prone is a given natural slope. All the above sound a bit pedantic, if not uninteresting, as would an article on tsunamies three weeks ago. Not so with the people of La Conchita in the Ventura County of California, who yesterday (1/11/05) lost their houses, built on the slope of a hill. History teaches that human societies are rather “mature” entities, as proven by their survival up to now. However, there are a few areas that they display rather immature behavior. These are: wars, quakes, and slides. After the calamity they bury the dead and forget. It takes the money earned in a lifetime to acquire a house for one’s family. So, the only people that will not forget are the ones in La Conchita who lost their houses. But why did the people of La Conchita built their houses on that hillside? Let us follow the procedure for acquiring a piece of land in the existing social system (of the civilized world, i. e. the US, etc). A family (usually a young middle-class couple) contacts the owner (??) of the land (personally or through an agent) in a PRIVATE deal away from the community of people that live in the area. The important points to be considered in the deal are the view from the hillside, the access road to the land, and the price. At no point there is a serious discussion of the stability of the slope of the hill.

To hold such a serious discussion this should be based on the following: a series of borings should be driven in the hillside soil down to at least 100 feet (the usual depth of the surface of a slide), a great number of soil samples should be taken and tested in a soils-laboratory. Finally, a civil engineer should write a report on the stability of the slope on the basis of the lab results. It is obvious that ordinary families cannot bear the cost of such a stability study. The couple buys the land, builds the house and lives happily ever after, until the next fatal heavy rain or quake. But, is there an alternative way for the couple to get a roof over their heads? We think there is a utopian (that is rational) way to do that. The solution of the problem should begin with the original inhabitants of the community that chose to live in a certain geographic area. If the houses are to be built on the slope of a hill,the first thing that the prospective community should investigate is the stability of the slope with the help of engineers.

The cost can be born by the entire community. So, when a young couple arrives in the area seeking a place to live the first thing they should do is contact the members of the community and get all the pertinent information about the land they intend to build on. This is going to be a COLLECTIVE transaction not a private deal. In a more advanced society the land should be given to the couple by the community as there would be no ownership of the land. Are there people who would agree with such a “utopian” alternative system? Yes, they are the survivors of La Conchita and the past and future La Conchitas. Also, the millions that survived the Indian Ocean tsunami who by now are willing to accept an alternative system of collective behavior. Parecon offers a very effective “guide” to start dealing with the extremely difficult problems of slides, tsunamis, and quakes. (Parenthesis: At some point in history someone should solve the mystery of the ownership of land. Is it Zeus, the Christian God, Allah, the Buddha, etc, etc, the ones that donated the land to the original humans? Let us take the case of Mount Pendeli, the mountain from which the marble of the Parthenon was quarried. The land of this huge mountain belongs to the local Greek Christian Orthodox monastery. The titles of ownership originate from the Turkish occupiers [!] of Greece between the 15th and the 19th century.

Since 1945, after WWII, the monks of the Pendeli Monastery have been selling this land to affluent Greeks for billions of dollars. The mystery gets even deeper if one were to ponder about the goods and services on which the monks spend this huge amount of money. Also, did the Christian God donate the land to Rumsfeld which he sold to that American actress who needed it to raise her twin children on a land surface a few hundred times bigger than the land on which the ordinary American family raises its children? End of parenthesis.) What about the communities with houses already built on hillsides? Again the actions should be collective (pareconish) ones. A list of possible actions could be as follows:

1. Check the slide-history of the wider area, especially by means of air-photo interpretation.

2. Carry an engineering survey (borings, lab-work, report), as a community.

3. Evacuate the area after a heavy rain.

4. If the engineering report concludes that the hillside is slide-prone: a) install a warning system (even if it is of limited reliability) with instruments put in the borings of the survey and b) accept the fact that the existing social system has forced you to make a mistake that could ruin your life by losing your house even if you survive a slide. It is interesting to note that the community of La Conchita has applied item 3 of the above list. “…(The) Ventura County fire officials asked residents…to leave voluntarily. About 200 complied…’ a few did not’..” (International Herald Tribune, Jan. 12, 05). Of course the dead are among those that did not leave. Which raises the socially and anthropologically interesting question of what kind of people were they? What was their opinion about Bush the Second and his Iraq war? Was their attitude “let the slide come” as it was of the courageous and benevolent President about the Iraqi Resistance fighters? Catastrophic (suddenly occurring) slides are not a very frequent phenomenon. Yet, why should even a single human being be forced to suffer the agonizing death of being buried alive? The people of slide-prone areas should act collectively as a community to protect themselves. The people of Redondo Beach, of Daly City, of Alaska, of Brazil (and its Favellas), of mountainous Greece, etc, etc can do that.

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