Workers rappelled down Cheyenne Canyon's walls Thursday afternoon, breaking away boulders loosened during heavy rains in mid-September.

At the same time, an excavator rumbled along steep slopes farther up the mountains west of Colorado Springs feverishly working to repair a 100-foot section of Gold Camp Road also damaged in what experts have called rains of "Biblical proportion."

Both jobs were necessary after more than 12 inches of rain fell on the slopes and cliffs that dump into the portion of Cheyenne Creek that flows through North Cheyenne Canon Park. The storm that lasted from Sept. 11 through Sept. 15 not only left streams, streets and homes flooded in the Pikes Peak region, it dumped floodwaters all the way to the Wyoming border.

Colorado Springs officials were forced to close North Cheyenne Canon Park and the U.S. Forest Service shut down Gold Camp Road.

Jeff Hovermale of the Forest Service stood next to where the road used to be Thursday and spoke above the roar of the excavator. He said more than 12,000 cubic feet of fill dirt would be needed to shore up Gold Camp Road and added that he has not seen a project "to this scale along forest roads."

That much dirt would fill about 600 large dump trucks.

The washed-out section is about midway between two mountain tunnels along the gravel corridor that links Helen Hunt Falls to the area near Bear Creek Regional Park. Hovermale said he expects the chore to be completed by mid-December.

Colorado Springs parks officials joined Hovermale and local media on a tour of the damaged slopes and repair work Thursday. Karen Palus, director of Parks, Recreation and Cultural Services, said North Cheyenne Canon Park is tentatively expected to reopen in early December.

The rock scaling work is part of a larger project in North Cheyenne Canon Park that cost the parks department more than $300,000, not including road repairs. Work began in September. Crews have cleared dangerous trees, reshaped steep slopes, completed extensive maintenance to the Mount Cutler and Columbine trails, and repaired washed-out roads.

The rock work is focused on areas directly above the roadway where there is "rockfall potential," said Chris Lieber, the city's park development manager. Lieber said a consulting firm was hired and assessed the slopes and cliffs. Yenter Companies pinpointed 10 areas that needed work. Two of those required "significant scaling," he said.

Crews were working Thursday to send rocks with cracks from water damage tumbling down the cliffs. They inserted thin air bags about the size of a book into the cracks, inflated them with compressed air, and broke away sections of rock. Workers have also removed large boulders left in precarious positions by earth that washed away.

"They are eventually going to fall," Lieber said. "Natural conditions are always going to win out."

Lieber said some boulders tumbled on their own and have settled into soft spots along the slopes.

"Once they settle in, they are going to be there for a long time," he said.