After $3.6 million and months worth of work, the underground Cheyenne Mountain Operations Center is ready for the monsoon.
The main entrance to the secretive underground complex was blocked by up to 12 feet of mud and debris Sept. 12, when 14 inches of rain hit the mountain in a day. Drainage systems that had worked well since the 1960s were overwhelmed.
And while the underground command center stayed operational through the storm, roads to get to it were blocked by mud, boulders and trees that washed down the mountain's near-vertical face.
"You can't fight it downstream, you have to fight it upstream," said Jason Cook, the complex's deputy civil engineer.
Once the debris was hauled away and the water receded, Air Force leaders took a hard look at the mountain to redesign its stormwater system.
Col. Travis Harsha said a key concern was making sure the deluge running from the complex doesn't flood neighbors in housing developments downhill.
"Safety has always been paramount," he said.
The new storm drainage system starts on the granite high above the entrance to the underground complex. Structures to catch falling debris were placed in stream channels running down the mountains face.
Near the mountain's main entrance, a debris-blocking system was installed along with a 6-foot culvert to channel water away to the storm drain system at nearby Fort Carson.
Thousands of tons of rock were installed along a stretch of road leading to the mountain to slow runoff and guide it into a pair of massive catch basins.
All that rain caused little damage in the tunnels that house the workings of the mountain.
"They built it well," Harsha said.
The facility was constructed in the early 1960s to serve as a missile warning and air defense command post that could withstand a 30 megaton nuclear blast.
The mountain now houses a backup command center for the North American Aerospace Defense Command and the rest of the 4.5 acres of tunnels is full, with most of the tenant list classified.
"If we were a hotel, we would have a no-vacancy sign," Harsha said.
But the September storm worried commanders that rainfall could do what most weapons couldn't - impact the underground missions at the site.
Initial work to clear debris at the mountain was conducted by Air Force and Army teams. Later, hydrologists, geologists and engineers checked the mountain to find stormwater fixes and determine whether all that water had damaged the granite.
The Air Force issued emergency contracts to repair damage and improve drainage. One issue for commanders: The debris at the north entrance took out fences designed to provide an extra layer of security for the place outside its blast doors.
Harsha said another key post-storm concern is protecting the mountain from wildfires that have struck the Pikes Peak region in recent years. They have done that by thinning trees and brush around the base.
"We're on it like gangbusters," the colonel said.
The next step, starting this week, is cleaning up the last vestige of damage from the storm.
Debris falling near the mountain's main entrance cracked a line leading to a device that separates oil from stormwater. Officials estimate that 10 gallons of heavy lubricating oil seepage from the mountain's diesel generator, was washed away.
Harsha said contractors will be checking the neighborhood downhill from the complex to find oil or oil-soaked soil so it can be hauled away.
While the oil isn't considered toxic and the release was small, Harsha said cleaning up remnants is part of being a good neighbor.
"We're going to start that cleanup next week," he said.