A report to Mayor Tom Bradley on last month’s flash fire that injured two workers at the city’s Hyperion Treatment Plant calls for comprehensive new safety procedures and equipment modification to pbevent similar accidents.
While the “exact cause” of the flash fire at the sewage treatment facility south of Los Angeles International Airport has not been determined, according to a private consultant’s report, the workers were allowed to begin repairs on a machine that was still dangerously hot and contained volatile materials.
The results of the investigation by Hercules Aerospace Co., a West Virginia firm hired by the city, are presented in a Nov. 8 report forwarded to the mayor this week by Edward J. Avila, city Board of Public Works president.
The Times obtained a copy of the report late Wednesday.
Two Workers Burned
On Oct. 3, James Cooke and Don Berg were removing a faulty plate on a hydro-extractor, a prototype machine at Hyperion that dries sewage for conversion to energy, when a volatile mixture of sludge exploded and seriously burned them. On Wednesday, both men, employees of private contracting firms, were discharged from Torrance Memorial Hospital after more than six weeks of treatment, a spokeswoman said.
The accident prompted the shutdown of the experimental project. The troubled $400-million Hyperion Energy Recovery System has cost three times more than originally estimated, is two years behind schedule and has undergone numerous modifications since another fire in February.
In a memo to Bradley accompanying the report, Avila appeared to concur with a union official, who said last month that the hydro-extractor had not cooled down enough before workers attempted repairs.
“The conclusion that is most significant . . . is the implementation of a formal written shutdown procedure for the hydro-extractor to obtain a lower temperature (less than 140 degrees),” Avila wrote. “This will mitigate the possibility of oil vapor being present and reduce the possibility of powder as a self-heating ignition source.”
Temperature Too High
The temperature of the machine at the time of the fire was 160 to 180 degrees, according to the consultant’s report, and “less than 140 degrees is considered essential” because that temperature is the flash point for oil present in the sludge being treated.
Nonetheless, the report states, the exact cause of the accident, which was described as a flash fire, “cannot be determined with certainty.”
In addition to the temperature of the machine, which may have created flammable oil vapors, the report cites as factors the combustible qualities of the mixture of sludge and oil, possible small leaks of oxygen into the machine and an “inrush” of oxygen during repairs.
“Fuel and oxygen were certainly present,” the consultant wrote. “Which fuel was first ignited by the ignition source is uncertain.”
The report calls for further study of the spontaneous “self-heating” properties of the sludge treated by the machine and of the possibility that a spark or static electricity ignited the blaze.
Among the key recommendations offered to prevent further accidents:
- Detailed written safety procedures for cooling down and preparing the machine for repairs.
- Comprehensive training for all personnel in those procedures.
- Installation of valves to regulate a continuous flow of nitrogen into the machine during the cooling process to prevent the intrusion of oxygen.
- Monitoring of flammable oxygen and vapor levels before any maintenance takes place.
- Implementation of a more reliable material for machine parts in order to reduce the frequency of repair and replacement.
- “As a minimum,” fire resistant coveralls, leather gloves and face protection for maintenance workers.
The city’s Bureau of Sanitation has prepared a program to instruct employees on safe work practices and plans frequent inspections at the plant to correct potential hazards, Avila said.