A Model for Risk Assessment of Wastewater Collection Networks

Wastewater collection networks are constantly faced with crises and risks, because of some problems during their operation. Assessment of risk in these networks is essential, because of its effects on human health and environment. In this paper a model is presented for increasing readiness of sewer networks to face the crisis. To calculate the network risks, at first possible threats are identified, then with the opinion of experts, the threats are ranked and those by higher hazard for the risk analysis are considered. Risk parameters, probability of threats, severity of their impact and vulnerabilities of network components have been measured by fuzzy multi criteria decision making methods, questionnaire and defined criteria. The relative weights of the criteria are obtained of paired comparisons by hierarchical fuzzy, Buckely method. Then Bunisson method is also used for comparison of the options‟ grade about any of the criteria. Thus the risk of any threat is achieved from the fuzzy multiplication of its independent factors including the threats occurrence probability, severity of its impact and network components vulnerability from the threats. Considering the magnitude of the calculated risks, threats are classified in several groups (low risk threats to high risk threat) and therefore approaches to dealing with each category are defined on the basis of those risks. These approaches are divided into three main categories, dealing with risk, risk transfer or risk acceptance. This method has been studied for a regional wastewater collection network in Tehran

Keywords:

Risk Assessment , Risk Management , Wastewater collection system , Multi Criteria Decision Making , Fuzzy Sets , Analytical Hierarchy process