Cal/OSHA, the state agency responsible for ensuring workplace safety, concluded its review of Chevron’s oil refinery in Richmond on Friday morning, clearing the way for the company to resume full production at the facility.
The refinery had been running at 60 percent capacity since a fire erupted at the plant last August.
The fire injured six people and sent a plume of toxic smoke into the air that caused more than 15,000 people to go to area hospitals complaining of breathing problems.
The fire was sparked by a rupture in a corroded pipe that Chevron had known about since 2002, but failed to repair or report to safety regulators until after the fire, state regulators testified at a hearing Friday.
The California Occupational Safety and Health program had previously issued an order barring use of the refinery's crude distillation unit - the heart of the plant - where the fire broke out.
WATCH: Raw Video of Chevron's Richmond Refinery Fire
Ellen Widess, chief at Cal/OSHA, told NBC Bay Area Chevron has made changes to safety procedures in the wake of the disaster.
The lifting of the order should not, however, be interpreted as an endorsement of the safety of the entire refinery, Cal/OSHA chief Ellen Widess said at the hearing.
State regulators strongly criticized Chevron for 25 examples of unsafe maintenance at the refinery, and fined the company $1 million -- the maximum amount allowable under law.
The company did not replace the corroded pipe that ruptured and caused the fire, and Chevron did not "follow its own emergency shutdown procedures" and did not protect workers, regulators found.
Chevron was pleased by the announcement and has previously said it planned to resume operations before the end of June.
"We have also implemented a number of actions based on the preliminary findings from our investigation of the incident in order to strengthen safety and reliability of the refinery," Chevron said in a statement.
Also Friday, Contra Costa County officials announced that they plan to conduct an extensive safety audit of the refinery .
The county sent a letter to Chevron stating its intention to inspect and evaluate the refinery's safety culture and practices, Supervisor John Gioia said today at a hearing in Richmond on the refinery fire. The hearing, led by state Sen. Loni Hancock, D-Oakland, and Assemblywoman Nancy Skinner, D-Berkeley, included reports from Cal/OSHA and other regulatory agencies on the fire investigation and regulatory response.
The county safety audit process announced today has only been used three times in the past 15 years, and the last time was in 2003, according to Randy Sawyer, the county's chief environmental health and hazardous materials officer.
The audit will be conducted by a consultant, to be paid for by Chevron, and an oversight committee created in cooperation with the City of Richmond, Sawyer said. It could take around six months to complete. The county's move to review the plant's safety management system came the same day that the California Division of Occupational Safety and Health lifted the order prohibiting use at Chevron's Crude Unit #4, according to agency spokesman Peter Melton.