Regaining ground

How to bring contaminated land back into use.
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Remediation based on risk assessment acknowledges that removing all contaminants from an area of affected land is not usually feasible.

Over hundreds of years, industrial activities including mining, chemical production, manufacturing of consumer goods and agriculture introduced pollutants into the soil, contaminating it along with groundwater, often over large areas. Past practices were different from today's: waste was dumped in an uncontrolled way or used in applications that are no longer acceptable, while unabated emissions to air and water had widespread impacts on surrounding populations and the environment.

Several notorious cases of pollution led to increasing public awareness of the risks related to the uncontrolled use and disposal of certain substances. One example is the mercury poisoning that emerged in 1956 in the Japanese city of Minamata, caused by emissions from a nearby chemical company that had bioaccumulated in fish eaten by local people. Another is DDT, the synthetic pesticide used extensively after the Second World War. DDT harmed wildlife, was identified as a potential human carcinogen and linked to premature births.

In the 1970s, concern grew that (re)using contaminated land could pose a serious risk to human health. In 1978, Love Canal – a neighborhood in Niagara Falls, New York, where a school and houses were built on and next to a former chemical waste landfill - became a national media issue in the United States. Numerous families exhibited serious health effects and had to be relocated. In 1979 a similar case occurred at Lekkerkerk in the Netherlands, where 300 families had to be rehoused because their homes were built on a waste dump.

Global economic growth together with population expansion has created the need to use additional land. Suitable uncontaminated land has become scarcer and awareness has grown that leaving land derelict has a negative and stigmatizing effect on the surrounding population, even causing feelings of insecurity and an increase in crime. At the same time, it is increasingly recognized that natural land and ecosystems have to be preserved and protected. All this has contributed to the realization that contaminated land should be brought back into use in a suitable and safe way.

It was quickly apparent that removing all contaminants from an area of affected land is unfeasible in almost all cases because of the cost and the time required. So the concept of remediation based on risk assessment was introduced as a valid and acceptable tool. Such an assessment estimates the nature and probability of adverse health effects in humans and the wider environment that could be exposed to chemicals in contaminated environmental media (such as soil and groundwater), now or in the future. It takes into account, for example, the nature of contaminants and their impact on human health, the way that people are likely to be exposed, and for how long.

Humans can be exposed in different ways: directly ingesting contaminated soil and groundwater; inhaling soil particles; consuming vegetables and fruit grown on contaminated land; inhaling volatile contaminants present in groundwater and migrating as vapors in buildings; and taking in contaminants through the skin.

The level of exposure depends on how the land is used. Obviously, residential uses – including schools, daycare centres and hospitals – are more sensitive than industrial uses where only healthy adults are present. Similarly, parks, football fields, golf courses and other recreational uses are less sensitive, since people spend only limited time in these areas. Sensitive land uses therefore require more stringent land management and/or remediation efforts. Clearly spatial land-use planning is extremely important, as well as a system that tracks the history of each piece of land so as to avoid future Love Canals and Lekkerkerks.

Increasingly, professionals working with contaminated land recognize that sustainability considerations are a key factor in holistic solutions, especially when dealing with the redevelopment of old industrial areas and bringing contaminated sites back to beneficial use. Sustainable remediation – integrating environmental, social and economic aspects – provides a framework for balanced decision-making in selecting the strategy to address soil and groundwater contamination. This is an integral part of sustainable land use.

Communication and stakeholder engagement are key to the success of any project, and trust between stakeholders needs to be built from the very beginning. Good communication is crucial for reaching a common understanding of a sustainable remediation management plan. The majority of stakeholders should accept and agree not just the final choice of redevelopment, but also the way to get there by choosing the most appropriate remediation and management options.

While risk assessment remains the basis for understanding the seriousness of contamination and its longer-term impact, sustainable remediation brings in other tools to better balance decision-making. Examples are: carbon footprint and lifecycle assessment; energy efficiency assessment; quality of life assessment; and cost-benefit analyses and financial risk assessment. Sustainable land management is the appropriate way to deal with contaminated land by: offering protection of human health and the environment; guiding the allocation of resources; and enabling the cost-effective management of risks, based on sound and agreed decision-making.

In 2010, The Network for Contaminated Land in Europe (the predecessor of the Network for Industrially Co-ordinated Land Management in Europe) published a Road Map to Sustainable Remediation that shows this process graphically. It has defined the way forward into the next decade. Sustainability considerations will truly bring together economics, environment and social needs in transforming contaminated land so that it is suitable for its future intended use and can be assimilated back into our communities.