An explosion Wednesday afternoon at the Imperium Grays Harbor Biodiesel Plant sent debris into neighboring properties and rattled windows two miles away. There were no injuries.

An explosion Wednesday afternoon at the Imperium Grays Harbor Biodiesel Plant sent debris into neighboring properties and rattled windows two miles away. There were no injuries.

A news release from Seattle-based Imperium blamed the 2:30 p.m. blast on over-pressurization of a glycerin-processing tank. The explosion damaged another tank containing sulfuric acid. Company spokesman John Williams says the 1,500-gallon sulfuric-acid tank was contained.

Imperium said the plant, between Aberdeen and Hoquiam, had been evacuated and that all six employees working at the site were accounted for.

The plant opened in 2007 and was built to produce up to 100 million gallons of biodiesel per year, according to Imperium’s Web site. In March, as a result of reduced demand for biodiesel, the company laid off 24 employees, the majority of its staff in Grays Harbor County.

The plant recently had begun producing biodiesel again but was not running at full capacity, Williams said.

Imperium was started in 2005 by John Plaza as Seattle Biodiesel, according to the company’s Web site. The company originally produced the fuel in Seattle. It no longer owns that facility; the Seattle plant was sold in June to General Biodiesel.

According to Imperium, glycerin is a co-product of biodiesel production. The company said the molasses-like liquid gave the appearance of charred material in the area of the blast but that there had been no fire.

According to The Associated Press, a large chunk of the tank was blown at least 100 feet away and crashed through a chain-link fence. The company said the explosion sent aluminum and insulation across the plant and into nearby properties.

The company said the plant will be shut down until a damage assessment can be made. Once Imperium officials are allowed access to the plant, they will conduct an investigation into what led to the blast, the company said.

Information from Seattle Times archives was used in this report.