City, county and UC San Diego officials will investigate what caused a load of refuse from a university chemistry laboratory to catch fire as it was being loaded into a trash truck Wednesday morning.
They will also attempt to determine what chemicals were in the refuse.
After the waste caught fire, the driver of the truck drove to the nearby Torrey Pines Glider Port, where he dumped the trash.
San Diego Fire Department officials decided to let the fire burn itself out to lessen the threat from the chemicals, which they feared might be explosive. The fire burned itself out after about six hours.
There were no injuries, and damage to the truck was minimal, according to a spokesman for the university's environmental health and safety department.
The truck, from a private trash collecting firm, picked up a container holding an unknown amount of material from a chemical research building at 11:15 a.m., Fire Department spokeswoman Ida Cheney said.
"As the trash (was) lifted over the truck, apparently there was . . . suddenly quite a bit of fire," said Scott Wilson, a university safety officer.
The truck driver dumped the burning waste in a vacant area at the glider port, near the south end of the Torrey Pines Golf Course, Cheney said.
San Diego firefighters responded to the blaze, as did city and county hazardous-waste management teams.
Firefighters decided not to try to put out the fire because they feared that some of the chemicals might react violently with water. They also wanted to prevent any toxic chemicals from soaking into the ground, Cheney said.
The Fire Department's hazardous-waste team decided to let the trash burn, and used blowers to make sure it was thoroughly destroyed by the flames.
Wilson said he suspected that the fire may have been the result of reactive chemicals improperly placed in a container for regular trash.
"We have a very thorough waste-management program at UCSD," he said. " . . . When they (laboratories) are finished with chemicals, we come by and pick them up, put them through the waste facility we operate, and dispose of them properly.
"Our suspicion is somebody bypassed that system and put one or more containers of chemicals into ordinary trash."
Wilson said that, when the trash was lifted over the truck, the bottles holding the chemicals probably "clinked together and broke," igniting quickly.
He said it may be difficult to determine the cause of the blaze because the "heat of fire would pretty well destroy any labels on the bottles."
Wilson said his department "will thoroughly review our disposal program and ask for even tighter voluntary compliance" from the university departments involved.