Environmental benefits of leaving steel-piled jacket platforms in place

Abstract

With many of the Bass Strait reservoirs having reached the end of their productive life, Esso has been planning and preparing for the decommissioning of facilities including the currently non-producing steel-piled jacket platforms (platforms). Given many of these platforms have been in place for several decades, it is important to understand the ecosystem that has established around them to ensure that the environmental impacts and risks of decommissioning are appropriately assessed. Esso undertook an offshore environmental survey in 2021 using a remotely operated vehicle (ROV) to collect visual imagery of the environment around a representative set of platforms (and pipelines), including reference sites (natural seabed environment), to supplement available literature with site-specific data. The Australian Institute of Marine Science (AIMS) performed detailed analysis of the fish and benthic communities that are associating with the infrastructure to provide insights into understanding the habitat value of the infrastructure. An equal or better environmental outcome assessment undertaken by Esso identified that preserving the marine communities that have established on and around the platforms is a key consideration between complete removal of platforms and the proposed end state of retaining the lower sections (minimum 55 m below mean sea level) of selected platforms in situ.