Experts learn from Exxon Valdez and Deepwater Horizon to plan for future accidents

July 13, 2015 - Five years ago this week, engineers capped the leaking Macondo well 1,500 meters below the surface of the Gulf of Mexico, effectively ending the largest marine oil spill in U.S. history. The Gulf spill started three months earlier, when the Deepwater Horizon (DWH) oil rig exploded into fire—an accident that killed 11 workers—and then sank into the sea. During the 86 days of the spill, 4.9 million barrels of oil and 200,000 metric tons of hydrocarbon gas spewed into the Gulf.

Earlier this month, BP, the principal developer of the oil field, announced a proposed $18.7 billion settlement with federal and state authorities for environmental and economic damage related to the spill. The deal would bring the total that the company will spend on the spill to more than $40 billion.

The DWH spill came two decades after the second-largest spill in the U.S., when the oil tanker Exxon Valdez ran aground in Prince William Sound, Alaska, and released 260,000 bbl of crude into the water there. The area’s cold, rocky beaches and larger ecosystem still show vestiges of the spill.