Soil pollution is widespread in industrial, urban and agricultural areas and is often the result of years of intentional or accidental discharge of pollutants. The methods of remediation are as varied as the pollutants and have to be adapted to each locality. Urban soil pollution is most commonly caused by lead previously used in cars and in house paint, or by insecticides used in gardens or under and around houses.

The health effects of lead on children (see Lead) can be greatly diminished by eliminating bare, dusty areas in the garden and play areas, and by scrupulous hygiene and removal of dust from the house. Vegetables grown in lead-polluted soil must be carefully washed and peeled, but the best idea is not to use root vegetables from such soil.

Pesticide pollution is mostly due to the use of arsenic or the long persistent organochlorine chemicals in past termite treatments. Although no longer in use, these organochlorines may still be present and may continue to emit toxic vapours which can penetrate into the living areas of the treated houses. The risk can be minimised by providing good ventilation under the houses. This also decreases the risk of future termite infestation by keeping the area dry. (See Termite treatments.)

If the area around the house has been treated, risk from insecticide vapour can be reduced by either removing the top 10 cm of the soil to somewhere further away from the house, or by sealing it with concrete. While the soil is being moved or disturbed the exposure to the pesticide vapour will be increased.

Industrial soil pollution can take many forms. Old gasworks sites are always heavily polluted with phenols and sulphur compounds. Heavily polluted industrial sites may contain chlorinated benzenes, chlorophenols, pesticides, dioxins and furans. Sometimes they can be remediated by a combination of biological methods and entombment of the most toxic soil in a constructed impervious area on the site. Biological methods involve selecting bacteria, which can decompose the particular chemicals found on the site, and assisting the bacteria's growth. The method is completely site specific and slow to be effective. Another technique for remediation is thermal adsorption and decomposition. In this the soil is heated and the desorbed contaminants decomposed by further heating. This technology has been used on some of the most contaminated soil at the Homebush Bay Olympic site.

Other sites, like oil depots or service stations with leaking underground tanks, are sometimes treated by digging up the soil and exposing it to air oxidation over many months. However, this is not sufficient if leaded petrol has leaked into the ground.

Chemical pollution of agricultural land is found in fields which have been treated with organochlorine pesticides (DDT, aldrin) in the past, or on fence lines where they have been used to protect the fence posts. Dip sites where chemicals were used to treat sheep and cattle are often heavily contaminated with arsenical compounds and organochlorines. There are many hundreds of such dip sites throughout the country and their rehabilitation for other uses is a major problem.

If you suspect the soil on your property may be contaminated, contact your local council or state environment protection authority for advice.