An index-based risk assessment approach for accidental contaminant release from waste management facilities during flood events

Student thesis: Doctoral Thesis

Abstract

Natural hazards can trigger technological disasters in installations such as waste management facilities, and chemical and processing plants, leading to explosions, fires, and/or the release of dangerous substances. The likelihood of these ‘Natech’ incidents can be exacerbated by climate change intensifying very wet weather patterns leading to floods. Rising sea levels may further contribute to heightened flood risk. Consequently, the number of ‘at risk’ installations to flooding is increasing, and this trend is expected to continue as our climate warms. The Seveso Directive provides guidelines for identifying installations handling dangerous substances and mandates safety measures to minimise the likelihood and impact of accidents. However, the risk of contaminant release during floods is not limited to installations falling under the Seveso Directive. Various small and medium-sized facilities, such as waste management facilities, often located near residential areas, also handle hazardous waste and pose a threat to both human health and the environment in the event of accidental release. This research assesses the vulnerability of waste management facilities to flooding. We use an adapted form of the Water Risk Index (WRI), originally designed for large-scale industrial facilities, to estimate risk of flooding to waste facilities on a facility-by-facility basis. The initial application of the WRI to waste management facilities revealed significant gaps such as the absence of detailed georeferenced areas representing the spatial extent of the waste management facilities, the neglect of the spatial context, and the lack of consideration for waste materials that can degrade into smaller particulates such as microplastics. Here we address these gaps to enhance the evaluation methods for understanding the impacts of flooding on waste management facilities and the potential consequences on the environment and community resilience. Three primary methodologies have been developed and tested in Great Britain (GB) to address the knowledge gaps. The first methodology determines the spatial extent of waste management facilities, providing a comprehensive understanding of their footprint. In testing their vulnerability to inundation, the results indicate that a decrease in flood likelihood corresponds to an increase in the number of affected waste management facilities and the severity of the impact. Specifically, out of the 1,049 facilities tested, 10% (23 sites) displayed more than 40% of their footprint at risk from high flood likelihood (with a 10% annual probability). These percentages rise to 33% (88 sites) and 35% (111 sites) for medium (0.5%) and low likelihoods (0.1%), respectively. The second methodology assesses the vulnerability of waste facilities to flooding at the national scale by considering contextual factors from physical and human geography. These factors form a new multi-index-based assessment considering hazard, vulnerability, and exposure. The aim was to identify hotspots that necessitate additional analysis at the local level to efficiently mitigate the risk. The overall risk index (categorised as low, medium, and high) is estimated for a total of 7,292 facilities across GB. Approximately 15% (1,094 sites) classified with a high-risk index are located in areas at high risk of pluvial flood likelihood. Medium and low flood risks increase these figures to 37% (2,697 sites) and 44% (3,204 sites), respectively. We show that facilities with a high-risk index outweigh those with medium and low risks, particularly in scenarios with a high likelihood of floods, whether fluvial or pluvial. These results indicate that for flood-affected waste management facilities, the vulnerability of receptors is frequently triggered at the full potential. Finally, the third methodology establishes a framework to assess the plastic mobilisation potential from waste management facilities by estimating the location and quantity of waste materials capable of releasing synthetic micro-components into floodwaters. The term Microplastic Releasers (MPRs) is introduced to describe waste materials capable of degrading into synthetic microplastic components. MPRs include plastic, synthetic textile, and rubber waste. When applying the method to waste management facilities across GB, the results indicate a significant amount of MPRs at high risk of fluvial flooding, totalling nearly 1 million tonnes. However, the impact of pluvial flooding is even more severe: in the case of flood events ranging from a 5-year to a 1,000-year return period, the exposure of MPRs to floodwaters increases tenfold, from 1 to 11 million tonnes. By integrating the methodologies developed in this research, hotspots for further research on risk management and mitigation at the local level can be identified. Stakeholders and policymakers may reconsider the placement of waste facilities to non-flood-prone areas. If relocation is not possible, mitigation measures such as the implementation of flood defences as well as site-specific containment systems designed to minimise the release of synthetic micro components during a flood event can be introduced. The results have significant implications not only for waste management practices but also for broader discussions on environmental management, risk assessment, and the resilience of industries in the face of climate change.
Date of Award14 Nov 2023
Original languageEnglish
Awarding Institution
  • University Of Strathclyde
SponsorsUniversity of Strathclyde
SupervisorChris White (Supervisor) & Doug Bertram (Supervisor)

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