Environmental and socio-economic impact assessment of Ekoreef, a multiple platform rigs-to-reefs development

The North Sea Ekofisk oil field is approaching the end of its production, and various options are being considered regarding future use or demolition of the platforms. One option is the rigs-to-reefs initiative. OSPAR and Norwegian national legislation contain provisions that allow for the creation of artificial reefs providing they do not hinder other users and do not cause significant pollution. More generally, the creation of sizeable artificial reefs using redundant offshore steel structures is only sensible if positive impacts outweigh negative impacts. At an early stage in the cessation process, we carried out an impact assessment to identify factors that would present special environmental or socio-economic risks or benefits. Thirty-nine impacts, positive and negative, were identified and grouped under the following headings: exploitable fish stocks (8); local biota (7); sediments (4); water column (2); energy and emissions (2); socio-economics (10); other (6). Techniques by which to estimate their likely severity in general and the potential for their reduction (negative impacts) or maximization (positive impacts) are summarized. Semi-quantitative severity scores for all impacts identified were assigned to each of 11 reef-creation options. These were totalled and the options were then ranked accordingly. From an environmental and ecological (including commercial fish stocks) perspective, the results indicate that reef use for protection would be a better option than use for commercial fishing, although differences between the two were not large. The rank order did not discriminate among four of the suggested reef locations. However, toppling in situ was clearly identified as the worst scenario, whereas reef creation at a relatively clean site offered the most promising perspective. Copyright 2002 International Council for the Exploration of the Sea. Published by Elsevier Science Ltd. All rights reserved.