The expression “preliminary risk assessment” appeared in connection with environmental protection in the early 1990s first, when remediation programs aimed at the elimination of permanent environmental damages were established with state support in several developed countries.
During the surveys performed in the preparation phase of these programs a multitude of pollution sources – jeopardizing the environment -, as well as sites potentially polluted or already damaged were recorded countrywide. Their order of magnitude – several ten thousands - evinces the necessity of a very money- and time-consuming remediation process, the implementation of which requires the setting of priorities to enable the ranking of remediation projects.
In order to determine priorities sites have to be characterised and compared principally on the basis of the magnitude of environmental and human health risk.
At that time only the so-called quantitative risk assessment methods were available, which had already been in use in the field of environmental protection in connection with the assessment and handling of industrial risks.
Methods of this kind were already applied f. e. in the course of the SUPERFUND remediation program in the USA in the 1980s.
In Europe the Netherlands were the first to start the countrywide organisation of remediation tasks and the application of risk assessment in remedial practice.
The quantitative risk assessment methods used for the specific risk assessment of polluted sites require a large input database, which needs detailed site investigations, measurements, investigations and observations. Further necessary information sources are statistical and experimental data banks.
As site investigations are rather expensive, the compilation costs of the necessary input database may amount to heavy expenditure and may significantly slow down the preparation of remedial actions, especially if there are many sites to be investigated. Upon the whole there is no need for very accurate data at the starting phase of remediation. Actually in order to support decision-making low-cost resources appropriate to give quick answers to the following two questions are required:
- on which of the recorded sites are remedial interventions presumably necessary,
- in the case of the latter which priorities should determine the ranking of the necessary interventions and the preparatory measures for those.
Considering the above-mentioned aspects most of the countries implementing remediation programs elaborated their preliminary risk assessment methods. These methods are based on the uniform qualitative evaluation of risk processes and require a minimum on on-the-spot measures using mainly available data.
The methods have different names in different countries: relative risk assessment method, reduced risk assessment model, uniform hazard evaluation method, national classification system for pollution sources and polluted sites, etc. All names are appropriate and reflect the typical methodological characteristics of the given preliminary assessment process.
Preliminary risk assessment methods came into use in Germany and Canada first. Afterwards the reduced risk assessment model and classification system for the priority ranking of contaminated sites was elaborated in France.
According to publications pre-qualification methods based on similar principles are used in Finland, Sweden, Switzerland and other countries. In the Netherlands the assessment system based on the hazardousness of activities and materials is mainly used for the pre-qualification of contaminated sites, but in some projects preliminary risk assessment methods are applied as well.
Great Britain has not established a state-supported countrywide remediation program yet. That is most probably the reason why the classical method of quantitative risk assessment has preference.
In the USA risk assessment methods were acknowledged and used in remediation practice in the middle of the 90s, in the course of the remediation aimed at the elimination of military pollution sources supported by the US Department for Defence.
In Hungary the elaboration of the preliminary risk assessment methods started in 1994 to promote the planned assessment and qualification of the point pollution sources endangering groundwater. Till now three versions of risk assessment methods have been elaborated in the framework of the National Environmental Remediation Program, and further developments are currently in progress.
Although preliminary risk assessment has been successfully applied in international practice for almost 10 years, in Hungary it is still one of the rather unacknowledged evaluation methods. The elaboration and application of the risk assessment method under elaboration is hotly debated, as there are significant differences in the ideas on it’s conception, use and the expectations towards it.
This booklet describes the methodological basis and application characteristics of preliminary risk assessment methods based on international experience.
Thereto – following to a short comparative analyses – you will find the presentation of the characteristics of the preliminary and of the detailed quantitative risk assessment and the significant differences in methodology and application.
International examples are mentioned to present possible methodological solutions and their differences (originating from strategies and theoretical approach).