unplanned events (non-emergency)
The semi-submersible drill rig and associated support vessels used for the exploration activity may be sourced from overseas locations and brought to the exploration area through international waters. Marine plant or animal species not native to Australia that have been introduced by human activities such as shipping are known as introduced marine pests. Marine pests attach themselves as biofouling to vessel hulls and internal compartments, anchor chains, fishing gear and recreational equipment. They can also travel in a vessel’s seawater system, including pipes, bilge and ballast water.
There are currently more than 250 introduced marine species in Australia, with 43 found in South Australian waters. While some are relatively harmless, others may become invasive when outside their natural environment, potentially threatening the environment, human health and the economy.
Unplanned discharge - diesel or non-aqueous drill fluid (NADF) spill during bunkering/transfer operations
During exploration, there is the risk of diesel fuel or non-aqueous drilling fluids (NADFs) being accidentally released to the marine environment. This could occur during bunkering and transfer operations between the support vessels and the drill rig.Due to the distance of the exploration activity from the nearest land, the drill rig will require refuelling. During this process, a diesel spill could occur as a result of bunkering hose failure, coupling failures, loss of connection, overfilling or leaking flanges, valves and hose connections. NADFs could be accidentally released to the marine environment if there is a failure of the rig’s drill fluid system, equipment failure or accidental valve release.
The risk and impact risk assessment scoping exercise identified a number of environmental risks that were not considered credible or applicable. Risks identified as not credible or not applicable do not form part of the risk assessment.