INDIANAPOLIS (AP) — Months after an uproar over BP's new water permit for its planned Whiting refinery expansion, state officials released a proposed air permit Tuesday the company needs approved before work can begin on the $3.8 billion project.

State environmental officials also set a public hearing, for Feb. 25 at the Hammond Civic Center, at which they will explain the permit's nuances and take public comments.

Environmental activists said Tuesday it would take them several days to digest the draft permit and a separate document detailing the changes the refinery would undergo to make it a hub for processing heavy Canadian crude oil.

The two documents, which run about 1,370 pages each, were posted online late Tuesday morning on the Indiana Department of Environmental Management's Web site.

Both are filled with technical descriptions and tables that activists will spend the next several days reading to grasp their meaning, said Erin Crofton, a resource specialist with the Michigan City-based Save the Dunes Council.

"We haven't even had a chance to look at it yet. That's a lot to go through, so we don't know if there's anything to complain about or worry about," she said.

IDEM spokesman Rob Elstro said Tuesday he did not have a breakdown of the changes in pollution emissions the proposed permit would allow. But he said IDEM expects the refinery's emissions to drop due to equipment upgrades planned as part of the expansion.

"Modification, upgrades, new equipment — the end result will be decreases from emissions from this facility, even though they'll expand its capacity to process Canadian crude," he said.

BP officials have said that since 2001, the 1,400-acre refinery's overall air emissions have declined 68 percent due to an ongoing modernization project that has cut sulfur dioxide, nitrogen oxide, particulate matter and other emissions.

BP spokesman Scott Dean said Tuesday in a statement that emissions of some individual components, such as sulfur dioxide and particulate matter, are expected to increase when the refinery project is completed in 2011. But he said levels of those pollutants "will remain below currently authorized limits."

Last summer, IDEM granted BP a wastewater permit that allows the Whiting refinery to increase the amount of ammonia it dumps into the lake by 54 percent and its discharges of suspended solids into the lake by 35 percent by 2012.

That permit sparked weeks of criticism from environmentalists who said the permit amounted to a reversal of decades-long efforts to reduce pollution in the lake.

In August, BP abandoned its plans to increase the amount of pollution it discharges from the refinery under that permit. Company officials said they would either find a way to stay within the limits set in its previous discharge permit or drop the expansion plans for the refinery about 20 miles southeast of Chicago.

Cameron Davis, executive director of the Alliance for the Great Lakes, said the Chicago-based group would study the permit closely. Davis said he's particularly interested if the expansion will boost emissions of mercury because that heavy metal ends up in the food chain, and in fish that people catch and eat.

In November, the U.S. Environmental Protection Agency alleged that BP violated a host of Clean Air Act provisions by making unapproved changes to its Whiting refinery that significantly boosted the plant's pollution emissions.

Those modifications caused "significant increases" in the refinery's releases of sulfur dioxide, nitrogen oxide, particulate matter and carbon monoxide, the EPA said.