What is an EMBA?

The environment that may be affected, known as the 'EMBA', is the largest geographic area where operational activities could potentially have a direct or indirect environmental impact under worst-case scenarios.

The EMBA is divided into an operational area for activities like drilling and vessel resupply, and a planning area where emergency response plans must be ready for activation in the unlikely event of an accident.

The EMBA is also used to define the broadest area where environmental values and sensitivities are defined, the potential impacts assessed, and control measured to mitigate these impacts developed.


Beach recognises the environmental, cultural, heritage, social and economic values in our activity and planning areas. We have a proud track record for safety and environmental performance, adhering to performance measures set out in environment plans and Safety Cases accepted by regulators.

Environment plans detail potential impacts from the proposed activities, and control measures to reduce and manage potential environmental impacts and potential risks to ALARP and acceptable levels.

ALARP stands for ‘As Low As Reasonably Practicable.’ It is a principle commonly used in the process of undertaking an environmental risk assessment and reducing potential impacts and risks. Click here for more information on how the National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA) assesses ALARP.

To define the extent of an EMBA, oil spill trajectory modelling is undertaken. Worst-case scenarios are factored into emergency preparedness plans.

In drilling a well this would be the uncontrolled loss of hydrocarbons from the well. Hydrocarbons are gas and condensate (a very light diesel-like fuel) for this project. The loss of hydrocarbons is modelled over winter and summer months under various ocean conditions and for a period of just under three months. A scenario of this type has not occurred offshore of Victoria and has only occurred once in the last 20 years offshore of Australia.

Beach also considers the loss of marine fuel from the sinking of a supply vessel. As per Australian Maritime Safety Authority (AMSA) guidance, Beach model the full loss of the largest fuel tank on the supply vessel. There are also no records of this occurring offshore of Victoria or Tasmania.

The modelling calculates the transportation, spreading, entrainment and dispersion in the sea and considers things like evaporation, biodegradation, sedimentation, emulsification and other environmental factors that naturally break down the hydrocarbons.

Modelling includes both stochastic and deterministic modelling:

  • Stochastic modelling is created by overlaying a large number (often hundreds) of individual computer-simulated hypothetic models to generate a large composite area that could theoretically be impacted. The primary use for this type of model is incident preparedness and planning.
  • Deterministic modelling is the predictive modelling of a single incident. This incident is then subject to a single sample of weather and sea conditions over time. This model is used for incident planning and predicting time to potential occurrences like shoreline contact.

Modelling is carried out for summer and winter conditions. It applies over 200 different scenarios where a hydrocarbon release could result in the spread of fuels in different ways:

  • Floating is visible oil on the sea surface in accordance with the Bonn Agreement (2009). This visible oil would be characterised by a rainbow / sheen on the sea surface.
  • Dissolved hydrocarbons that are not visible. These are the water-soluble component of the hydrocarbon that could potentially impact marine life.
  • Entrained hydrocarbons that are suspended in the water column. Entrained hydrocarbons are not visible and could potentially impact marine life.
  • Shoreline hydrocarbons that contact the shoreline. The volume used is based on scientific risk assessments, with a low level of hydrocarbon loading used (10g/m2). This is approximately two teaspoons per square metre.

The modelling is used in preparing environment plans. An assessment of the likelihood and consequences of any hydrocarbon release is undertaken. This must be reduced to ALARP through a range of control measures and include detailed response plans.

For more information about Beach’s emergency response, click here.

For more information on hydrocarbon release modelling and why it is required for the preparation of environment plans, click here to watch a video on the NOPSEMA website.