What is a Tier 3 Spill

Tier 3 spill is one of the three levels of oil spills as categorized by the International Petroleum Industry Environmental Conservation Association (IPIECA).

Oil spill preparedness and response is one of the critical issues addressed by IPIECA guidelines and publications. IPIECA identifies spill preparations and containment and clean-up plans to be a fundamental priority which all companies in the oil and gas industry must include in their internal emergency management plans. As part of its recommended oil spill preparedness principles, IPIECA has developed a system of ranking spills by a scale consisting of three tiers.


International Petroleum Industry Environmental Conservation Association (IPIECA) is a not-for-profit association which supports the global oil and gas industries. The organization has a focus on social and environmental issues and concerns. They encourage and facilitate discussions and cooperation among companies within the oil and gas industry. This cooperative effort helps all of the operations involved benefit from shared insights and developments to address and solve major critical issues that may be too large for individual companies to resolve on their own.

The IPIECA has defined the three tiers according to various characteristics based more on the capabilities of the response than on the volume or size of the spill. They compiled a definition of 15 response capabilities, which work in conjunction with one another to provide immediate relief. Capabilities include in-situ controlled burning, shoreline clean-up, wildlife response, and waste management.

  1. Tier 1 events use locally held resources and are less severe spills allowing the containment and addressing by a company’s internal spill management team. These accidents tend to be operational in the cause and happen at or near the operator's facility. This team provides the initial response and include trained on-site staff and local contractors. 
  2. Tier 2 spills are accidents which may require national or regional response teams with specialized knowledge to intervene. These events extend outside the operational area of the oil or gas facility. A higher number of people are involved in a Tier 2 response. This team has access to additional training and equipment such as aircraft, communication, and the ability to institute mutual aid agreements between groups and government bodies.
  3. Tier 3 accidents are global in need for necessary, available, large-scale resource response. 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. The third tier will respond with industry-controlled, cooperatively-held equipment, stockpiles, and personnel. Examples of the type of common pool resources (CPR) and equipment available with a Tier 3 response include the high-volume aerial dispersant, at-sea and large-scale containment equipment, and specialized shoreline and inland clean-up capabilities. This team can respond to remote drilling sites which may not have access to extended local capabilities. Personnel on this level are equipped to train and direct large numbers of workers through wide-spread logistics. 

​​​​​​​IPIECA publishes the Tiered preparedness and response: Good practice guidelines for using the tiered preparedness and response framework which summarizes current views on oil spill preparedness and response. The most recent publication is dated January 2015. IPIECA guidelines are internationally-recognized and help to guide the industry's response of personnel, equipment, and support to spill events.

Accident Preparations and Tier 3 Spills

Companies in the oil and petroleum industries must prepare for spills, and other types of accidents and facilities must have a plan in place dictating the process for addressing, containing and cleaning up any spills that may occur. However, even with strict and well-planned emergency procedures and strict preventive measures, a company cannot always guarantee that emergencies will not happen. Accidents, natural disasters, and equipment failure can all cause spills of varying degrees. The 2010 Deepwater Horizon spill is an example of a Tier 3 event.