ESG Poster ESG4: A quantitative method for evaluating ecological risks associated with long-term degradation of deep-sea plastic-containing infrastructure
Alexander N. Testoff A *A Montrose Environmental Solutions, Sandy Springs, GA 30350, USA.
The APPEA Journal 62 - https://doi.org/10.1071/AJ21429
Published: 3 June 2022
Abstract
Poster ESG4
Presented herein is a newly developed quantitative approach for assessing potential ecological risk resulting from long-term degradation of deep-sea plastic-containing infrastructure. The risk characterisation involves four iterations of modelled ‘risk’ through forward or backward calculation of a deterministic hazard quotient, mathematically defined as the ratio of estimated exposure to a reference dose (or concentration) for a similar exposure period. The assessment focuses on direct effects of microplastics exposure, wherein exposure concentrations are based on modelled estimates of microplastic mass formation resulting from structure deterioration over time. Predicted no effect concentrations (PNECs) protective of slightly-to-moderately disturbed ecosystems and ecosystems of high conservation value were determined based on a species sensitivity distribution (SSD), in accordance with the current Australian and New Zealand Guidelines for Fresh and Marine Water Quality. Each iteration of risk characterisation is performed irrespective of burial, with varying exposure unit dimensions (i.e. geographically localised and broader regions of microplastic dispersal) and degrees of plastic degradation, designed to conservatively bound the risk characterisation. Additionally, two SSDs derived from different ecotoxicological data sets prioritising either particle shape or marine species are also provided for a sensitivity analysis of the PNEC. Thus, the bounding exercise encompasses all possible outcomes. The risk characterisation approach is reviewed for a case study of two larger plastic-containing flowline assets in an oil production field offshore of Australia. The outcome of the risk assessment is the same for all model iterations: degradation of the subsea plastic-containing flowlines does not pose a risk to the local marine community.
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Keywords: degradation, ecological risk, microplastics, NEBA, net environmental benefit analysis based comparative assessment, offshore decommissioning, plastics, risk assessment, toxicity.
Alex Testoff is a registered professional environmental engineer and senior consultant at Montrose Environmental Solutions. Mr Testoff holds two degrees in environmental engineering: a Bachelor of Science from Ohio State University and a Master of Science from John’s Hopkins University. Mr Testoff has 8 years of experience in contaminated site assessment and remediation consulting in the United States, primarily practicing in the CERCLA (Superfund) and RCRA regulatory areas, and in application of net environmental benefit assessment based comparative assessment (NEBA-CA) and habitat equivalency analysis (HEA) in decision-making associated with competing decommissioning strategies for international offshore oil/gas developments. Mr Testoff has unique capabilities in quantitative ecological risk characterisation and terrestrial ecological studies, and has developed an approach to quantitatively assess the potential for ecological impairment due to microplastics exposure resulting from long-term degradation of plastic-containing structures in offshore oil/gas developments. |
