The explosion occurred just before 2:30 p.m. at the Imperium Renewables plant, said Hoquiam Chief of Police Jeff Myers.
The 10,000 gallon tank containing heated glycerin overpressurized and ruptured, causing the glycerin to mix with the cold air and create a large vapor plume. The glycerin, a co-product of biodiesel production and a non-toxic substance, was spread across the incident area, giving the appearance of charred material.
The explosion sent debris into a 5,000 gallon sulfuric acid tank, causing a leak. However, the leak was contained to the immediate area, and no one was injured.
Twisted metal and debris from the explosion was spread as far as 100 yards from the site, and the glycerin tank now has a gaping hole in it.
Firefighters evacuated some nearby businesses as a precaution, including the Westport Shipyard and Grays Harbor Paper.
The company spokesperson said the plume after the explosion was likely water vapor and there was no fire.
The company will bring in teams to clean up the mess as fire investigators look for the cause.