Kármentesítési Konferencia - 2003. május 21.

The Methodology of Quantitative Risk Assessment in Polluted Site Remediation in Hungary
(A Research and Development Project Commissioned by the Ministry of the Environment and Water Management)
Dr Gyula Dura
National Institute of Environmental Hygiene
Gyula Dankó
Golder Associates Hungary Ltd.
Dr Ferenc Gondi
BGT Hungaria Ltd.

Quantitative risk assessment in cases of certain polluted sites aims to determine the concentration value of hazardous priority substances and thus fix the desired or target clean-up values.

While applying this methodology one must determine the clean-up target value around the source of pollution and the necessary extent and way of remediation actions to reduce risks. All this should be done with the view to the transport processes, exposure pathways and the extent to which environmental, ecological and human receptors are expose to.

Risk assessment is a step by step iterative procedure in the course of which initially overestimated values of the risk level are successively adjusted to approach the real extent of risk potential receptors are exposed to. The method of risk assessment evaluates the extent of pollution in the pollution source – pathway – receptor system. Domestic practice puts special emphasis on the protection of extensive aquifer systems, which are the main source or drinking water resources within the Carpathian Basin. The method has to be applied in a way, which would prevent the shallow ground waters from penetrating the pollution detected in soil. In case pollution has already reached groundwater, measures must be taken to prevent it from spreading beyond fixed boundaries (the points of compliance).

What decides the rate of environmental risks and, consequently, the type of required measures of prevention, is the degree of concentration of hazardous priority substances, which the pollutant - through the migration started at the source of pollution – reaches or may reach the receptors with, and what kind of receptors will or can be reached. The level of risk is estimated by comparing actual and tolerable exposure levels.

With the help of risk assessment one must determine the target concentration of hazardous priority substances at the sources of pollution – that is the environmental quality standards (the D standards). These standards guarantee that pollutants do not spread beyond fixed boundaries and pose no risk to the environmental elements as well as ecological and human receptors.