The U.S. Army Corps of Engineers is still gathering information to learn how construction of the final five miles of Interstate 485 might affect streams, waterways, wildlife and other public resources.
The public can offer comments through Aug. 14 about the expected environmental impact of the proposed project, an eight-lane freeway that would stretch from Old Statesville Road to I-85.
N.C. Department of Transportation plans to begin construction within days of receiving a building permit.
"We look forward to the completion of this next step in the project process, and for the roadway work to get under way as soon as it can," said Barry Moose, the Division 10 engineer who will oversee the project.
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The Corps of Engineers is charged with protecting U.S. wetlands, streams and waters in North Carolina.
The agency could issue a permit to the state, impose modifications or conditions, or deny the state's request based on concerns about water quality or other issues.
Comments from the public will be used to measure the potential impact construction might have on endangered species, historic properties, water quality and the other public interests.
The Corps will consider requests for a public hearing, if a valid concern is raised.
Building the last section of the loop, between Interstates 77 and 85 in northeast Charlotte, would be a large-scale project.
Plans call for work on the interchange at Old Statesville Road near I-77 and new interchanges at Prosperity Church and Mallard Creek roads.
That portion of the project is expected to be completed in December 2014 at a cost of $139 million.
At the same time, crews would widen 6.8 miles of I-85 to eight lanes from Mecklenburg County into Cabarrus County while also reconfiguring the I-485 interchange at I-85.
A bridge on Mallard Creek Road over I-85, north of the proposed interchange, would be realigned and expanded. About a half mile of Mallard Creek Road would be realigned.
The $92.2 million interchange project is scheduled to be completed in July 2014. The $125 million widening project is expected to be completed in November 2013. Construction is expected to have an impact on 14,155 linear feet of stream channel and 8.09 acres of wetlands, according to N.C. DOT.
Impaired streams within the project area are Clarks Creek, Stony Creek and Rocky River.
NC DOT proposes to provide compensatory mitigation to a state ecosystem enhancement program for "impacts" to U.S. waterways.