RIASSUNTO
Abstract
It is increasingly important that decision makers for large capital projects (including development and decommissioning project phases) evaluate all project alternatives to determine the optimal final project configuration. The decision making process must take into account several important aspects including the long-term environmental impact or benefit of various project alternatives. Determination of the optimal project alternative often has long-term cost implications. In recent years, several innovative tools have been developed to streamline and optimize the decision making process. One of those is the use of the Net Environmental Benefit Analysis (NEBA) to determine the environmentally superior project alternative.
Here we utilized an innovative approach to the NEBA process by developing a semi-quantitative model that provides a relative ranking of project alternatives based on the expected environmental benefit. Our use of NEBA includes evaluation of initial project impact, impact recovery rate, and final (i.e., post-recovery) benefit level for each considered project alternative. The NEBA tool utilizes a streamlined approach designed to rely on a consensus scoring approach to various project attributes. The results of the model provide a relative ranking of project alternatives based on their net environmental benefit and irrespective of project cost or other considerations. In this respect, our approach provides a "pure" environmental vision of the project. As a consensus approach it is ideal for use in workshop formats with stakeholders and regulators avoiding lengthy iterations to determine a project outcome.
Our case study is made to rank five different project alternatives for offshore platform jacket decommissioning following evaluation of ten environmental aspects. Specific environmental aspects considered include the physical and chemical quality of air, water, and sediments at the project location. The ecology of marine fish, benthic organisms, mammals, and seabirds are also considered as are impacts to fisheries, coastal and terrestrial ecology. We bounded impact recovery rates to 100 years and evaluated five different recovery slope factors in the NEBA model. Following application of scoring and specific weighting factors to each environmental aspect, a quantitative NEBA score was developed for each project alternative evaluated. The result of our NEBA approach was a quantitative ranking of project alternatives in the context of the environmental benefit of each approach.
Our approach provided a comprehensive evaluation of project alternatives and returned a clear environmentally superior project alternative. The results of this approach provide project development decision makers with a cost effective and efficient tool to make defensible decisions to choose the most appropriate project alternative.