(Adds 2017 waiver update)
WASHINGTON, March 28 (Reuters) - The U.S. Environmental Protection Agency is likely to release its decisions on applications for small refinery waivers from the U.S. biofuel laws for 2018 in April, three sources familiar with the matter said on Thursday.
One of the sources said the 2018 waiver decisions could come in a couple of weeks. But refiners were expecting to find out about their petitions before the end of the month, which is the deadline for proving compliance under the U.S Renewable Fuel Standard for the 2018 calendar year.
The RFS requires refiners to blend certain volumes of biofuels like ethanol each year or purchase blending credits from those that do. But small facilities with a capacity of less than 75,000 barrels per day that can prove compliance would cause them significant financial strain can seek exemptions.
The EPA granted an additional 2017 small refinery waivers from the nation's biofuel laws, bringing the tally to 35, the agency disclosed on Thursday.
The EPA vastly expanded the program under President Donald Trump, granting waivers to plants of oil majors, including Exxon Mobil Corp and Chevron Corp, drawing ire from the corn industry, a key Trump constituency. The number of small refinery exemptions granted grew from seven in 2015 to at least 35 in 2017, EPA data shows.
There is still one outstanding application for 2017, EPA data shows.
The RFS program has been an economic boom for corn farmers in the Midwest, but merchant refiners say it has added hundreds of millions of dollars in compliance costs.
For 2018, there are a total of 39 petitions pending, according to EPA's website.
The EPA was not immediately available to comment.
Reporting by Humeyra Pamuk in Washington and Jarrett Renshaw in Philadelphia; editing by Chizu Nomiyama, Matthew Lewis and Dan Grebler