An integrated approach to environmental assessment for decommissioning outcomes

Abstract

As the Esso/BHP infrastructure in Bass Strait is prepared for decommissioning, it is imperative to develop an enhanced understanding of the environment that has evolved around the infrastructure over the past 50 years of production operations. To meet this need, Esso is progressing an integrated environmental assessment program. The first stage of the program recognised that Esso held a wealth of underwater remotely operated vehicle (ROV) imagery collected over many decades of routine inspections. Working in partnership with third-party marine scientists and biologists, the ecological value of this imagery was assessed. Approximately 1000 h of subsea imagery was analysed to identify species to the lowest possible taxa. To supplement this information, Esso then undertook comprehensive offshore environmental surveys, collecting further underwater imagery to assess marine biota, fish and benthic communities during the summer of 2020/2021. Esso also engaged a leading Australian research organisation to design an environmental survey for the collection and analysis of sediment samples around targeted infrastructure, including reference sites, to increase our understanding of the potential impacts different decommissioning options may have, including disturbance and resuspension of sediments. This integrated approach to environmental assessment has enabled industry, leading marine scientists and research organisations to work collaboratively to better understand the ecological role of oil and gas infrastructure in Bass Strait. This knowledge will assist in identifying optimal decommissioning outcomes for all infrastructure types.