How to deal with combined soil layer & groundwater contaminations?

When a contamination is present in both soil and groundwater, both concentrations can be entered simultaneously in S-Risk. S-Risk will first calculate the outdoor and indoor air concentrations separately for each soil layer and for the groundwater layer. Afterwards, the maximum of these calculated outdoor air concentrations and of each indoor air concentration (if the scenario requires such) is taken forward to the exposure assessment and risk characterization step. So, the soil layer-specific concentrations resulting from volatilization are not summed together, nor are the concentrations resulting from volatilization from soil and groundwater. Instead, it is the maximum contributing layer that determines the final exposure & risk.
In application III, this poses a problem. Since S-Risk only calculates critical concentrations for one single layer at a time, it can not provide guidance when multiple layers significantly contribute to the risk together. In these cases, it is advisable to calculate critical concentrations for each layer separately, ignoring the contamination in the other contributing layers. This is explained in more detail in the OVAM guidelines for soil remediation experts, see http://www.ovam.be/sites/default/files/21-02-2014_Richtlijnen_BSD.pdf (section on "Locatiespecifieke saneringsdoelstellingen voor bodem en voor grondwater").
 
last modified on 24/11/2014 - 08:59

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