Linking Management Responses to Quantitative Assessment of Cumulative Environmental Impact Consequences

Abstract As part of the Cumulative Environmental Impact Study for Australia's North West Shelf (NWS) province, and in the absence of suitable techniques linking management responses to cumulative impacts, a methodology was developed to assess cumulative impact consequences, both on a qualitative and quantitative level, for existing and future activities. An Impact Consequence Assessment Matrix was developed, derived from the combination of Environmental Effect (qualitatively or quantitatively assessed from ‘Serious’ to ‘Non-Significant’) and Effect Duration (‘Permanent’ to ‘Transient’). In a manner familiar within risk matrices, the combined position within the Matrix defines the Impact Consequence Level. Using these defined impact consequences, ALARP principles are applied to environmental impact assessment in a structured and systematic manner to guide management responses, in a similar manner to their traditional use within risk assessment. The technique was applied to the assessment of cumulative impacts for both oil & gas and non-O&G industry activities affecting the offshore and nearshore marine, atmospheric and terrestrial environments on the NWS. Due to the very high levels of environmental assessment and management embedded into the design and operation of existing projects, individual environmental impact consequences were typically quantified at the lower impact levels which are tolerable without further additional management action. Some individual and a number of cumulative effects from multiple projects/activities resulted in higher level impact consequences requiring management response appropriate to the level and certainty of consequence. This innovative methodology has the ability to identify appropriate environmental management actions, for currently operated projects and potential future projects, based on quantification and ranking of individual and cumulative environmental impacts across all environmental settings. It is immediately applicable for environmental managers to help better manage the environment for which they are responsible, as well as a tool to assist with environmental planning of future projects.