It could be another week before Tesoro Hawaii officials are able to check inside a liquid asphalt storage tank to determine what caused it to smolder on Tuesday, the company said.

Tesoro, the state's only producer of asphalt, won't resume production until the investigation is complete.

The tank can hold 25,000 barrels of liquid asphalt and should be less than half full by the end of today, Tesoro spokesman Nathan Hokama said yesterday. Investigators cannot check inside the tank for damage until it is empty, Hokama added.

The tank contained 18,000 barrels Tuesday. It is being emptied as customers take delivery of liquid asphalt.

During Tuesday's incident, there was smoke but no flames from the tank. The company evacuated workers from the tank farm area at Campbell Industrial Park.

Tesoro Hawaii has plans to reconfigure other tanks to increase its liquid asphalt storage capacity to 100,000 barrels by the end of July, Hokama said.

Reach Rod Ohira at rohira@honoluluadvertiser.com.