A Qualitative Approach to the Seismic Estimation of Wastewater Treatment Plants and Potential Impacts on the Hydrosphere

Many quantitative and qualitative methods have been developed to estimate the seismic vulnerability of Wastewater Treatment Plants (WWTPs). The research approach using questionnaires is the most common qualitative process to quickly access estimation results. In the present study, the Experts’ Judgment method was implemented. A representative questionnaire was distributed to a hundred and sixteen (116) operators of Greece’s WWTPs according to proportional stratified sampling for seven months. The questionnaire was based on the main parameters that contribute to seismic vulnerability (structural, non-structural and operational matters). The examination of the results included the search for reliability and validity. Their collection also revealed that the average seismic vulnerability of the samples was found at a low level after a direct question, and was slightly increased after analyzing a group of questions. In the case of soil–water pollution during the post-seismic period, the answers showed low percentages for the contribution to the seismic vulnerability (at the partial mode), and divided answers existed at low and slightly increased percentages. Non-structural and operational vulnerability somewhat increased the percentages in the judgments. During the 24 h post-seismic period, the possibility of soil–water pollution was expected at low percentages and it remained constant. The results of this study could be compared to future surveys for qualitative approaches to disaster risks or could be used in addition to the results from quantitative methods.