MARTINEZ, Calif. -- Oil manufacturing giant Tesoro has agreed to pay a $4 million settlement for violations of air pollution regulations found at the company's Martinez refinery.
Bay Area Air Quality Management District officials said in a statement today that regulators found during a seven-year investigation that waste fluids were periodically drained into the refinery's on-site sewer and water treatment system, allowing propane and butane to evaporate into the air, district officials said.
The air district documented the draining practices from 2007 to 2014 and found violations as recently as in 2013 and early 2014. Once informed the practice was illegal and dangerous, Tesoro committed to stopping it, according to the air district.
Draining directly into the on-site sewer system and bypassing required abatement technology contributed significantly to ozone and smog, according to the air district.
"We require Bay Area refineries to control their emissions at every step of their process," air district executive officer Jack Broadbent said in a statement. "Through the air district's aggressive enforcement program, these violations were discovered and this uncontrolled release of air pollution stopped."
Tesoro officials acknowledged the penalty today and said the company strives to fix any regulatory violations once brought to its attention.
"Tesoro takes compliance with environmental regulations seriously and strives to comply at all times," Tesoro officials said in a statement. "In all cases, Tesoro responded quickly to the cited incidents once they were identified, and has taken corrective measures to avoid their recurrence."