A damaged flame arrestor was the cause of a gas pipe explosion that rattled businesses in Iwilei and prompted the evacuation of hundreds of employees and store customers on Sept. 10.

The explosion near the Dole Cannery and Dole Office Building ripped apart the plastic gas pipe, which was three-fourths of an inch thick. No one was injured.

State heath official Steven Mow today said landowner Weston Solutions Inc. determined the cause of the explosion after conducting an investigation.

Weston has been working to restore the soil at 616 Iwilei Road, a site formerly used for manufacturing gas. Mow said Weston was injecting chemicals into the ground to remove toxins such as tar and benzene.

The pipe carried byproduct gases to a burner, where the gases would be burned off. But a damaged flame arrestor allowed flames into the pipe, causing the explosion, Mow said.

Mow, the state project manager for the site, said Weston will not be fined because it followed procedures agreed to by the state Department of Health and that there was no sign of negligence.