1. Generally, remediation means providing a remedy, so environmental remediation deals with the removal of pollution or contaminants from environmental media such as soil, groundwater, sediment, or surface water for the general protection of human health and the environment or from a brownfield site intended for redevelopment. Remediation is generally subject of many regulatory requirements, and also can be based on assessments of human health and ecological risks where no legislated standards exist or where standards are advisory.
2. In the USA the most comprehensive set of Preliminary Remediation Goals (PRGs) is from the Environmental Protection Agency (EPA) Region 9. A set of standards used in Europe exists and is often called the Dutch standards. The European Union (EU) is rapidly moving towards Europe-wide standards, although most of the industrialised nations in Europe have their own standards at present.
3. Once a site is suspected of being contaminated there is a need to assess the contamination. Often the assessment begins with preparation of a Phase I Environmental Site Assessment. The historical use of the site and the materials used and produced on site will guide the assessment strategy and type of sampling and chemical analysis to be done. Often nearby sites owned by the same company and have been reclaimed, levelled or filled, are also contaminated. For example, a car park may have been levelled by using contaminated waste in the fill. Ceiling dust, topsoil, surface and groundwater of nearby properties should also be tested, both before and after any remediation. This is a controversial step as: No one wants to have to pay for the cleanup of the site; If nearby properties are found to be contaminated it may have to be noted on their property title, potentially affecting the value; No one wants to pay for the cost of assessment.
4. In the US there has been a mechanism for taxing polluting industries to form a Superfund to remediate abandoned sites, or to litigate to force corporations to remediate their contaminated sites. Other countries have other mechanisms and commonly sites are rezoned to "higher" uses such as high density housing, to give the land a higher value so that after deducting clean up costs there is still an incentive for a developer to purchase the land, clean it up, redevelop it and sell it on.
5. Standards are set for the levels of dust, noise, odour, emissions to air and groundwater, and discharge to sewers or waterways of all chemicals of concern or chemicals likely to be produced during the remediation by processing of the contaminants. These are compared against both natural background levels in the area and standards for industrial zones and against standards used in other recent remediations. If the emission is emanating from an industrial area, it does not mean that in a nearby residential area there should be permitted any exceedances of the appropriate residential standards.
Monitoring for compliance against standards is necessary to ensure that exceedances are detected and reported both to authorities and the local community.
Enforcement is necessary to ensure that continued or significant breeches result in fines or even a jail sentence for the polluter.
Penalties must be significant because otherwise fines are treated as a normal expense of running business. Compliance must be cheaper than to have continuous breeches.
6. Remediation technologies are many and varied but can be categorised into ex-situ and in-situ methods. Ex-situ methods involve excavation of effected soils and subsequent treatment at the surface, In-situ methods seek to treat the contamination without removing the soils.