DECOMMISSIONING OLD PLANTS

DECOMMISSIONING OLD PLANTS
There are three aspects:
– old plant and equipment,
– old dump-sites,
– polluted soil.
Old fertilizer plants are being shut down for economic or environmental reasons, and phosphate and
potash mines are being mined out. The problem of site remediation and clean-up of past contaminated
sites is fast becoming a fact of life for many plants that have been careless about leakage of chemicals and
on-site disposal in the past. The process of cleaning and restoring polluted soil and water is a complex
and costly undertaking, for which the plant/site owner is normally liable. Legal prudence dictates a
regulated framework for plant decommissioning and site remediation. No matter how thorough a voluntary
cleanup may be, there can be no protection from the possibility of subsequent litigation. In any case, the
industry has a “duty of care” obligation with respect to disposal to external disposal sites. Many
governments are now requiring by law that companies clean up their sites. This is often under specific
‘contaminated sites’ legislation, or general environmental regulation
The diverse range of chemicals, and the difficulty of recovering them from the surrounding soil groundwater,
means that clean-up is very expensive. Many of the contaminated sites requiring most urgent attention
are former landfills.
To date there are no clear guidelines to ‘how clean is clean’, with the result that many companies are
unsure of how far to go. A number of countries such as the USA, Canada, France, Germany, The
Netherlands, Switzerland, the U.K. and Australia have attempted to prepare guidelines as to soil standards
expected from successful clean-up operations.

In the USA, the Comprehensive Environmental Response, Compensation and Liability Act, popularly
known as Superfund, addresses this problem with procedures including preliminary assessment, site
inspection, remedial investigation, feasibility study (including a definition of remedial methods and a
calculation of the respective costs), public comment and/or hearing, and design and construction of the
remedial project. This process can take several years before the project is actually implemented, and
subsequent periodic monitoring may also be involved.
As regards the options, removal of soil has the advantages of being quick and certain, factors which are
important for a developer. Removal of the contaminated soil to a landfill has generally been the cheapest
method of remediation to date, but with the tighter regulation of landfill this method may become more
expensive. Cleaner soil is brought in from another part of the site or elsewhere to replace the soil removed.
Removal to landfill does not eliminate the contaminants and the transport adds to environmental costs
but the transfer of contaminants to properly designed and managed disposal sites has its advantages.
Capping involves covering the contaminated soil. The top layer is usually clay in order to minimize the
amount of rainwater reaching the contaminated layer. Below the clay layer is a capillary break, often of
rubble, to prevent water from the contaminated layer rising towards the surface through capillary action.
There may be vertical barriers to prevent the horizontal movement of the contaminants.