There is a steep decline in oil tanker spills worldwide over the last 46 years according to an international agency that tracks petroleum releases into the marine environment.

The global safety record for oil tankers has improved in step with the global safety record for the maritime industry. Today, the worldwide incident frequency involving oil tankers is among the lowest of all marine vessels; only a fraction of the incidents reported for oil tankers resulted in the release of oil.

The International Tanker Owners Pollution Federation (ITOPF), based in London, reports an average of 1.7 large spills per year from tankers in this decade compared to 24.5 per year in the 1970s. Industry safety is steadily improving — the number of tanker spills has fallen 50 per cent since 2000-2009, for example.

The downward trend is continuing despite a doubling in the volume of crude oil, petroleum and gas transported by tanker between 1970 and 2016. Quantities of oil released each year have also plunged.

“The ongoing reduction in the amount of oil spilt through accidents involving tankers is encouraging news for tanker operators and governments alike as they continue to work to improve standards of operations in sea-borne oil transportation. Today, some 99.99 per cent of crude oil transported by sea arrives safely at its destination,” the ITOPF noted in a news release.

The ITOPF data includes all spills greater than 700 tonnes. In 2016, there was one spill in that range, worldwide.

The capacity of a medium-sized tanker, such as the Aframax vessels that call at Trans Mountain Pipeline’s Westridge Marine Terminal, is about 120,000 tonnes fully loaded. (Tankers departing Westridge load to about 80 per cent of capacity).

Trans Mountain is proposing to increase capacity of its pipeline system to 890,000 barrels per day from 300,000 at present. The Trans Mountain Expansion Project will potentially increase tanker traffic to Westridge from about five ships per month to about 34. Even then, Project-related tankers would represent less than seven per cent of large-scale vessel movements in the area — and less than half of all tanker traffic in the Juan de Fuca Strait.

Trans Mountain has operated Westridge for more than 60 years without any tanker-related oil spills. Post expansion, Trans Mountain will continue to load the same types of double-hulled vessels it does today, and those ships will travel the same well-established, well-managed marine route through the Salish Sea.

Det Norske Veritas, an international marine risk consultancy that carried out the marine oil spill risk analysis for Trans Mountain, found the region’s robust marine safety regime is well managed, with important risk controls in place for all traffic, for oil tankers in particular, and meets global standards. Post expansion, the likelihood of a credible worst-case spill involving a laden Project-related tanker would continue to remain an unlikely event, estimated by DNV as once in 2,841 years.

Increased probability of oil spills due to an increase in Project-related tanker traffic will be mitigated by additional marine safety and prevention measures proposed by Trans Mountain and included in the 157 Project conditions set down by the National Energy Board, of which 34 directly address marine activity.

These measures, such as the requirement to extend tug escorts for laden tankers to cover the entire route between Westridge and the mouth of the Juan de Fuca Strait, will help maintain the probability of tanker-related oil spills in the region at levels similar to that existing today.

Notwithstanding that, Trans Mountain is committed to making significant enhancements to the region’s marine safety regime to minimize the risk of a spill, including enhancements to oil spill response capability through investments in the Western Canada Marine Response Corporation.