The Trump administration is expected to roll back an Obama-era regulation meant to limit the leaching of heavy metals like arsenic, lead and mercury into water supplies from the ash of coal-fired power plants, according to two people familiar with the plans.

The Keystone pipeline system, an addition to which has been the subject of environmental protests for years, leaked about 383,000 gallons of crude oil in North Dakota, covering an estimated half-acre of wetland, state environmental regulators said.

The waiver enables Icahn’s CVR Energy Inc (CVI.N) to avoid tens of millions of dollars in costs related to the U.S. Renewable Fuel Standard (RFS) program. The regulation is meant to cut air pollution, reduce petroleum imports and support corn farmers by requiring refiners to mix billions of gallons of biofuels into the  nation’s gasoline and diesel each year.

Just one day after Environmental Protection Agency (EPA) Administrator Scott Pruitt told lawmakers on Capitol Hill that the agency did not have plans “at present” to target California’s special fuel economy waiver, the Trump administration announced that it would be putting a six-year hold on Obama-era standards for fuel efficiency, starting in 2020, while at the same time revoking California’s waiver to set its own standards.

The Trump administration is expected to launch an effort in coming days to weaken greenhouse gas emissions and fuel economy standards for automobiles, handing a victory to car manufacturers and giving them ammunition to potentially roll back industry standards worldwide.