A soil test allows a land owner to balance the potential impact of harm from soil contamination against the cost of undertaking a cleanup operation with the advice of a soil testing lab.
Soil testing is used as part of contaminated land rehabilitation projects to determine the presence and levels of harmful substances. A site is deemed to be contaminated when areas or the entire site has toxic chemicals in the ground that are harmful to humans or the environment at levels higher than those normally found in the region.
Soil testing companies are able to test for the presence of heavy metals like arsenic, lead, mercury, and zinc, other toxic metals such as cobalt, beryllium, nickel, and chromium, carcinogenic solvents like toluene and benzene, oils, fuel additives, radioactives, cyanide, pesticides, poisons, and fertilizers.
These substances can make their way into the ground from sites of heavy industry like smelters and factories, manufacturing plants, transit infrastructure like airports, docks, the roads, rail yards, and other vehicle depots, from leaking storage tanks and pipelines, runoff from agriculture, waste disposal sites and dumps, and even from commercial and residential sources.
As well as direct exposure, contaminants can make their way into environments that have never directly housed toxic substances, by blowing onto the site from neighboring properties through the wind, or leeching into the local soil and groundwater through the underground aquifers.
Once a soil test determines that toxic substances are present on a site, you need to consider how likely it is to affect those who come into contact with it. This depends very much on which substances are present and their quantities, where the site is, and what it shall be used for.
Some contaminants can cause harm to humans simply by inhaling dust from the air, or by contact with the skin and mucus membranes such as the eyes and mouth. In other cases, drinking tainted water can cause health problems. Towns which have high levels of heavy metals in the environment show increased rates of birth defects, retardation of newborns, lower IQs, and increased rates of many types of cancer.
In agricultural areas, plants and livestock can also be affected by these contaminants in the same way, and after being tainted, can pass on toxic substances to anything that eats them through several stages of the food chain.
In residential areas where children are likely to be present, contaminated soil testing is crucial, as lower concentrations of toxins are considered acceptable when compared with zones near heavy industry like ports and rail yards.
Moreover, children typically come into closer contact than adults with the dirtier parts of the environment by their nature, whether that means getting dirty while playing or ingesting dirt directly.
Government guidelines for contaminated soil testing and management vary across different regions, however, they tend towards an approach of risk management: It is necessary that some areas become polluted for the wheels of industry to keep turning, so town planning focuses on concentrating heavy polluters with waste disposal, landfill, and high-risk operations like chemical factories, away from the residential and commercial districts. When soil tests show the presence of toxic substances, it does not always make sense to launch a clean up operation, at least until levels get so high as to violate EPA regulations.
Instead, what action is to be taken depends on likely it is that the contamination will cause harm. The risk of damage to business and lives must be balanced against the potential impact of such harm occurring and the cost of remedy.
Fortunately, there are many ways you can commence soil remediation following unwelcome test results, with potentially cheaper options available for sites that have a low risk of causing harm.
Ideally, the leading soil testing labs will be able to advise you on which of these is the most appropriate for a given site.
In extreme cases, it may be necessary to completely excavate the affected soil, and seal it in below ground pits or an alternative waste storage repository. This is the method used to decontaminate areas affected by radiation and radioactive fallout, such as nuclear test zones, and the aftermath of nuclear power plant accidents.
Modern landfills are usually interleaved with layers of thick plastic membranes where there is a risk of contaminants reaching the groundwater, thus spreading.
Agricultural soil affected by excessive fertilizers and pesticides can be reconditioned by flushing with large quantities of water, as the containments tend to be concentrated water-soluble salts. Some contaminants can be bound in place with the addition of cement, while other harmful substances can be broken down by burning, rinsing with biodegradable chemical solvents, or with the addition of microbial agents into the soil.