JEFFERSON COUNTY - It is the last unfinished segment of a beltway that would serve the Denver metro area. If the planners of the Jefferson Parkway are successful, the toll road could be completed in 3 to 5 years.

If the Sierra Club has its way, the project won't be built as planned.

The Sierra Club labeled the 10 mile stretch of the Jefferson Parkway as one of the 50 worst projects in America. The Sierra Club has several concerns about the project, including the urban sprawl it says the road will cause. The group is mostly concerned about a three mile stretch of the roadway that will be built on land that was previously part of the Rocky Flats Nuclear Weapons facility.

"Anyone who was here paying attention knows that this land, lovely as it is, is plutonium laced and the Sierra Club is very concerned about putting a highway through an area that is plutonium laced," Rebecca Dickson, co-chair of the Sierra Club's Indian Peaks Group, said.

"You put a highway through here you are going to tear up the land. Whatever plutonium is in the ground gets tossed up into the air," Dickson said. "The Sierra Club believes that doing that could lead to cancers possibly. People who live here or work here are going to develop cancer that they otherwise would not develop."

The Jefferson Parkway Public Highway Authority acquired the three mile stretch of land that parallels Indiana Street at the end of 2012. The parcel represents about 100 acres of land along the eastern edge of the Rocky Flats National Wildlife Refuge.

Rocky Flats operated as a nuclear weapons facility during the cold war years from 1952 until 1992. Once it was closed as a weapons facility the cleanup of the property was finally declared finished in 2005. It was designated as a wildlife refuge in 2007, but much of the property remains closed to the public.

Supporters of the Jefferson Parkway point to the improved transportation it will provide and the economic development it will spur.

"It will also, as was demonstrated by the Denver Regional Council of Governments to lead to a net increase in regional air quality and will increase mobility for people transportation of all kinds throughout the metro area," said Bill Ray, executive director of the Jefferson Parkway Public Highway Authority.

Ray says there have been numerous studies done over the years by federal and state agencies that have concluded the property on which the Jefferson Parkway will be built is safe.

"There is nothing that we have seen that there is anything above background radiation that is present throughout this particular section of what was formerly part of the Rocky Flats National Wildlife Refuge," Ray said.

The Jefferson Parkway now faces a 14 to 18 month environment study process with the Colorado Department of Transportation.

The project is planned as a public-private partnership which means a private company will design, build, operate and maintain the toll road.

Ray says the Jefferson Parkway Public Highway Authority plans to monitor the construction, especially the portion built along Rocky Flats.

"It is our full intention to work in cooperation with the Colorado Department of Health, the Jefferson County Health Department and other appropriate offices to make sure there is accurate and appropriate monitoring through the course of construction," Ray said.

For their part, the Sierra Club plans to continue fighting to stop the project.

"We're going to fight until the day they start digging it up and then we might continue to fight it. It is just not a smart move," Dickson said.