Raising the game in environmental assessment: Insights from tiering practice

The organised transfer of information between Strategic Environmental Assessment (SEA) and Environmental Impact Assessment (EIA) processes – also known as tiering – has the potential to enhance the overall efficiency and effectiveness of environmental assessments and improve the coherence of information to support decisions. Nevertheless, research on tiering practice is limited and the added value of tiering to SEA, EIA and planning processes remains largely unexplored. This paper addresses this knowledge gap by examining tiering practice across sectors and planning tiers in the Republic of Ireland. It reviews nine SEA environmental reports and associated EIA reports, supplementing the review findings with 14 national expert interviews. The research reveals that SEAs can streamline processes by shaping alternatives, anticipating project-level issues and mitigation, and thus setting the terms of reference for EIA for more focused assessments and actions. When SEA and EIA ‘talk’ to each other, there is greater coherence, purpose and clarity of information which can result, ultimately, in better integration of environmental considerations across tiers, helping ensure that impacts are not significant on the ground. Although more apparent and effective in certain procedural stages, overall, tiering streamlines and strengthens environmental assessment processes, ‘raising the game’ through improved practice.