In town planning, brownfield land is an area of land previously used or built upon, as opposed to industry or mining and therefore may be contaminated by hazardous waste or pollution. Generally, designated brownfield sites exist in a town's industrial section, in abandoned factories or other previously high-polluting buildings. For example, many dry cleaning establishments produced high levels of ground contaminants in previous years. In the process of cleaning contaminated sites, surprises are frequently encountered, such as buried railroad tank cars containing wastes.
Some governments prohibit the development or use of such land, others legally require that such areas are reused for housing or for new commercial use in order not to destroy further arable land. The redevelopment of these brownfield sites is an important part of new urbanism.
For historical reasons, many brownfield sites are located close to important thoroughfares such as highways and rivers; their reclamation can therefore be a major asset to a city. This is being done in Atlanta, for example, where the Atlantic Station project is developing the large brownfield left by the former Atlantic Steel plant.
In the United States, reclamation is accomplished by health codes and Environmental Protection Agency (EPA) regulations. Again in the U.S., the EPA, together with local and national government, often provides funds for the cleanup of designated sites, as well as tax incentives for cleanup that is not paid for outright (specifically, cleanup costs are fully deductible in the year they are incurred  (http://www.epa.gov/brownfields/bftaxinc.htm).)
In the United Kingdom, contaminated land is dealt with by part IIA of the Environmental Protection Act 1990, which requires Local Authorities to search their area for potentially contaminated land and, where it is deemed necessary, carry out site inspections. Responsibility for funding lies with the original pollutors, in line with the 'Polluter Pays Principal'
See also: remediation