DEFINITION of 'Tier 3 Spill'
One of the three levels of oil spills as categorized by the International Petroleum Industry Environmental Conservation Association (IPIECA). Tier 3 spills are the most severe; they cannot be contained with the resources of the producing company and require substantial external resources to deal with them.
BREAKING DOWN 'Tier 3 Spill'
The IPIECA has defined the three tiers according to various characteristics. Tier 3 spills usually require resources from stockpiles of national or international cooperatives. In most cases, these co-ops will be subject to governmental control.