No one was seriously hurt in the accident.
Since then, the state has tightened laws regulating hazardous-waste facilities, and Environmental Quality Industrial Services has paid out more than $200,000 in reimbursements to the town of Apex and its residents.
The leak at the EQ plant on Investment Boulevard sent several large plumes of chlorine gas into the air. A large fire broke out, sending flames more than 100 feet into the sky and setting off multiple explosions. The fire raged for more than a day.
EQ agreed in October 2007 to not to rebuild its Apex site to settle a dispute with state regulators. The company agreed to pay more than $400,000 in penalties, fees and reimbursements to the state.
The state Division of Waste Management levied a record $553,225 fine against the company in March 2007, citing previous violations of the company's hazardous waste permit at the Apex site, including unreported fires and chemical leaks.