SAVANNAH, Ga. — A mining company seeking to dig for minerals near the vast wildlife refuge in the Okefenokee Swamp has reworked its plan to substantially shrink the mine's initial footprint in an environmentally sensitive area near the Georgia-Florida line.

The Army Corps of Engineers made public Friday a new permit application submitted by Twin Pine Minerals of Alabama, which withdrew its original proposal last month. The company wants to mine for titanium dioxide less than 3 miles (4.8 kilometers) from the swamp's edge.

The swamp is home to the Okefenokee National Wildlife Refuge, the largest federally protected refuge east of the Mississippi River, covering nearly 630 square miles (1,631 sq. kilometers). Critics have warned the mining project could cause irreparable harm to the swamp's fragile ecosystem that serves as habitat to alligators, bald eagles and other protected species.

The company's new permit application submitted March 4 would shrink the size of the initial area to be mined to 898 acres (3.6 square kilometers), compared to a proposed 1,450 acres (5.87 square kilometers) under the original proposal. Twin Pines' application calls the new acreage a "demonstration mining project" to show that minerals can be extracted "in an environmentally responsible manner."

"We believe it fully addresses points raised in our discussions with the U.S. Army Corps of Engineers about reducing the size of our permit area," Twin Pines President Steve Ingle said in a statement Friday.

The company's initial proposal last year said it ultimately plans to expand its mining operation to six tracts of land covering 12,000 acres (48.5 square kilometers).

"Twin Pines understands once it gets a foot in the door and gets the first phase permitted, it'll face much less procedural difficulty in gaining access to the larger 12,000 acre plot," said Christian Hunt of Defenders of Wildlife, a conservation group.

The U.S. Fish and Wildlife Service, which manages the Okefenokee refuge, said in a letter to the Army Corps in October that there's "great uncertainty" surrounding how mining near the swamp's edge might affect its ability to hold water. That's because the soil would lose its distinct layers after it's scooped at average depths of 50 feet (15 meters). Once minerals are removed, the soil would be returned to the ground as a homogenized mixture.

"The Service cannot definitively say that the mining proposal will significantly affect the environment," the agency said its letter. "However we have concerns that the proposed project could pose substantial risks for adverse impacts to (the Okefenokee refuge) and the surrounding environment that may be irreversible even with mitigation."

Twin Pines earlier this year released a 91-page report detailing its own scientific studies that concluded the proposed mining "will have negligible impact" on the swamp.