The costs of after-care of landfills consists of regular costs for monitoring and maintenance, and a sum to cover environmental risks in the after-care period. Before 2003 the financial impact of environmental risks of landfills in The Netherlands, in general, was covered by a fixed percentage of the regular after-care costs. This system did not include site-specific aspects. For this reason the Association of Dutch Provinces (IPO) decided to introduce the probabilistic Risk-analysis method.
The probabilistic Risk-analysis method is being used to estimate the costs of environmental risks, such as a large and uncontrolled contamination of groundwater or local damage of top cover. The probabilistic risk assessment method is objective and requires input from landfill engineer experts. Proper documentation of input data is needed as well as communication with landfill operators is of vital importance to achieve a broadly based acceptance.