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Legacy pollution

Pollution caused by historical use of a chemical

  • 14 min read
  • 6 chapters

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These chemicals often have outsized impact in countries’ jurisdictions with little or no environmental monitoring or regulation—because the chemical were often produced in new jurisdictions after they were banned in more heavily regulated jurisdictions. Often in these countries, there is a lack of capacity in environmental regulatory, health and civic infrastructure to address the impact of the pollutants.

The impact of legacy pollutants can be visible many years after the initial polluting process, and require environmental remediation. Grassroots communities and environmental defenders frequently advocate for responsibility of industry and states through environmental justice action and advocacy for recognition of human rights, such as the right to a healthy environment.

Brownfields

Brownfield is previously developed land that has been abandoned or left underused, and which may carry pollution or a risk of pollution from previous industrial use. The definition varies and is decided by policy makers and land developers within different countries. The main difference in definitions of whether a piece of land is considered a brownfield or not depends on the presence or absence of pollution. Overall, brownfield land is a site previously developed for industrial or commercial purposes and thus requires further development before reuse.

Many contaminated post-industrial brownfield sites sit unused because the cleaning costs may be more than the land is worth after redevelopment. Previously unknown underground wastes can increase the cost for study and cleanup. Depending on the contaminants and damage present adaptive re-use and disposal of a brownfield can require advanced and specialized appraisal analysis techniques.

Mine tailings

In mining, tailings or tails are the materials left over after the process of separating the valuable fraction from the uneconomic fraction (gangue) of an ore. Tailings are different from overburden, which is the waste rock or other material that overlies an ore or mineral body and is displaced during mining without being processed. Waste valorization is the evaluation of waste and residues from an economic process in order to determine their value in reuse or recycling, as what was gangue at the time of separation may increase with time or more sophisticated recovery processes.

Tailings are likely to be dangerous sources of toxic chemicals such as heavy metals, sulfides, and in some cases radioactive content. These chemicals are especially dangerous when stored in water in ponds behind tailings dams. These ponds are also vulnerable to major breaches or leaks from the dams, causing environmental disasters, such as the Mount Polley disaster in British Columbia. Because of these and other environmental concerns such as groundwater leakage, toxic emissions and bird death, tailing piles and ponds have received more scrutiny, especially in developed countries, but the first UN-level standard for tailing management was only established in 2020.

Abandoned mines

An abandoned mine refers to a former mining or quarrying operation that is no longer in use and has no responsible entity to finance the cost of remediation and/or restoration of the mine feature or site. Such mines are typically left unattended and may pose safety hazards or cause environmental damage without proper maintenance. The term incorporates all types of old mines, including underground shaft mines and drift mines, and surface mines, including quarries and placer mining. Typically, the cost of addressing the mine's hazards is borne by the public/taxpayers/the government.An abandoned mine may be a hazard to health, safety or environment.

Abandoned gas wells

Orphan, orphaned, or abandoned wells are oil or gas wells that have been abandoned by fossil fuel extraction industries. These wells may have been deactivated due to becoming uneconomic, failure to transfer ownerships (especially at bankruptcy of companies), or neglect, and thus no longer have legal owners responsible for their care. Decommissioning wells effectively can be expensive, costing several thousands of dollars for a shallow land well to millions of dollars for an offshore one. Thus the burden may fall on government agencies or surface landowners when a business entity can no longer be held responsible.

Orphan wells are a potent contributor of greenhouse gas emissions, such as methane emissions, contributing to climate change. Much of this leakage can be attributed to failure to have them plugged properly or leaking plugs. A 2020 estimate of abandoned wells in the United States was that methane emissions released from abandoned wells produced greenhouse gas impacts equivalent to three weeks of US oil consumption each year. The scale of leaking abandoned wells is well understood in the US and Canada because of public data and regulation; however, a Reuters investigation in 2020 could not find good estimates for Russia, Saudi Arabia and China—the next biggest oil and gas producers. However, they estimate there are 29 million abandoned wells internationally.

Abandoned wells have the potential to contaminate land, air and water, potentially harming ecosystems, wildlife, livestock, and humans. For example, many wells in the United States are situated on farmland, and if not maintained could contaminate soil and groundwater with toxic contaminants.

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