More problems have been found at the Cambria County site. DEP has ordered the company to stop injecting gas into its storage wells and submit a clean-up plan.
The rule covers conventional oil and gas sites that have already been built or drilled. Reducing VOC emissions is expected to also lower leaks of methane, a potent greenhouse gas.
Low-producing wells provide just 6% of oil and gas production in the U.S. But a new study found they emit half of the industry's climate-warming methane.