Site Suitability Analysis

The implications of installing a new landfill or expanding an existing landfill can be extremely controversial and extremely complex with the possibility of endangering many people if precautions are ignored or overlooked.  California’s largest toxic waste landfill located in the central valley in Kettleman city plans to expand its facility, but concerned state officials placed a moratorium on the expansion until an investigation regarding effects of the landfill on drinking water is completed.  Reports of higher than normal levels of arsenic have been found along with birth defects in the area.  Whether these are directly related to the landfill or a byproduct of the pesticides and other chemicals widely used by the agricultural community has yet to be determined.

As far as the expansion of landfill, a site suitability analysis still needs to be performed. A site suitability analysis takes many different factors into account and then determines where the best locations for a specific activity to take place should be, or where a specific structure should be built.  Different activities as well as different types of structures obviously use different factors to narrow down the best place. Generally a site suitability analysis finds locations where all the desirable factors are overlapping, or where all the undesirable locations are not present.  It is a very efficient way to determine the best site for building, or performing a certain activity.

In the case of the landfill expansion site suitability test five factors were taken into account to determine the best locations to enlarge the current landfill.  Slope, distance from streams, land cover, distance from the existing landfills, and the drainage of different type of soils were the five factors that were used to determine the ideal expansion sites.  While some site suitability analyses treat each factor equally our analysis weights each factor based upon its overall importance. The type of soil and its drainage properties along with the slope of the terrain were each weighted at .3, while distance from streams was weighted as .2; land cover and distance to existing landfills were weighted as .1. The weighting of all five factors gave a final output combining all five factors into one standardized ranking system.

While a site suitability analysis is very useful for visualization of an areas viable options for expansion, it must also be backed up by field operations.  The city of Kettleman may already be experiencing negative effects of the landfill and would be further impacted by any type of expansion.  The investigation must be completed determining the impacts of the landfill in its current state.  In general site suitability test are useful in determining viable areas that should then be followed up by extensive field work to assess the areas that are being suggested.

Overall Suitability Analysis Function is an extremely powerful tool to have access to.  It not only saves huge amounts of time, labor, and money it is one of the most efficient ways of assessing land suitability.  While it is an extremely useful guide to model reality, it should never substitute reality.  Suitability analyses should always be confirmed in the field and many more tests should be conducted to confirm your finding.  Suitability Analysis is to be used as a model that should always backed up by tangible evidence such as drainage properties, slope surveys, soil composition, watershed examinations, etc.  Suitability analyses will continue to be a valuable tool as long as they are used responsibly and are always checked for accuracy.