Photonics Makes Refinery a Good Neighbor

Kathleen G. Tatterson

RODEO, Calif. -- As part of a "good neighbor" agreement, Unocal Corp. plans to incorporate seven infrared, ultraviolet and laser sensors into what it calls the world's most comprehensive refinery air-monitoring system. The agreement ends two years of negotiations prompted in part by a 16-day chemical leak in 1994 that reportedly sickened 60,000 nearby residents.
Unocal will use the data from these sensors to compile and submit a monthly chemical emissions report to the Bay Area Air Quality Management District, the Contra Costa County Health Department and various community groups. The company will also make raw data available to the public.
The enhanced setup will scan for 35 toxic chemicals; standard volatile organic compound monitors test only for hydrogen sulfide and sulfur dioxide. The system will also enable the company to obtain a county land-use permit to manufacture cleaner-burning fuels.
Unocal has contracted with Terra Air Services of League City, Texas, for the project, which should be on-line by late June.
The contractor will install each of the seven sensors atop a concrete sonotube inside a 10 3 5 3 5-ft shelter. The laser beam from each unit will travel a half-mile to a retroreflector, which deflects the beam back to the unit using 160 corner-cube mirrors.

Clear warning
The tranceiver then compares the information with the system's database of 300 chemical compounds. If it detects unacceptable chemical levels, the system warns workers.
Unocal representative Kevin Elliott said the agreement is unique to the Rodeo, Calif., refinery, and that there are no immediate plans to install the system at Unocal's other two refineries.