The state Health Department will also be investigating the fire at Hawaiian Waste Systems, a spokeswoman said.
Health Department spokeswoman Janice Okubo said investigators will be visiting the site to determine whether proper procedures were followed and if the company has proper permits.
Investigators will also check to see if any problems have been caused by runoff from the water used to extinguish the two-alarm blaze.
In May, the Health Department fined Hawaiian Waste Systems $40,000 for the illegal storage of waste at Campbell Industrial Park.
The company is contesting the fine.
Okubo said the Health Department and Hawaiian Waste Systems are discussing a possible settlement.
About 20,000 tons of trash piled up at the company’s warehouse last year after the federal government denied Hawaiian Waste Systems a permit to ship the plastic-wrapped bales of Honolulu city trash to the mainland.
The company had signed a contract with the city to dispose of the waste. The contract was canceled last summer and the company has been trucking the trash to the HPOWER garbage-to-energy plant since September.