Damaged equipment intended to contain flames 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 yesterday said landowner Weston Solutions Inc. determined a damaged flame arrester was the cause of the explosion.

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 gases from the toxins to a burner, where the gases would be burned off. But a damaged flame arrester 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.

Mow said the remediation work at the site has been suspended while Weston works on a new design that improves safety.

Mow said the state is also looking for a different approach to take the toxins out of the soil.

"At this point, we’re going to see if there are any alternatives," he said.

Dave Griffin, Weston’s operations manager in Hawaii, said the damaged flame arrester had a perforation that allowed flames into the gas pipe.

Griffin said in the redesign, the company will use the same technology but build in redundant safety systems.