Cheyenne Mountain North Portal work nearing completion

  • Published
  • By Dave Smith
  • 21st Space Wing Public Affairs staff writer
CHEYENNE MOUNTAIN AIR FORCE STATION, Colo. --  Just more than two years ago the Colorado Springs area experienced what some called a 500-1,000 year rain storm. Anywhere from 10 -14 inches of rain reportedly fell in a 72-hour time frame causing tremendous flooding and mudslides from Ft. Collins to Colorado Springs.

Included in the catastrophic aftermath was Cheyenne Mountain Air Force Station. Fortunately the facility is located deep underground, secured in the granite of Cheyenne Mountain. Unfortunately, the underground complex's main entrance, the North Portal, was in the path of a massive mud and rock slide. The slide deposited about 7,200 cubic yards of debris on the North Portal access road while destroying drainage culverts, retaining walls, and undermining pavement.

The ensuing projects to not only restore, but prevent similar events in the future, are nearly complete. The final thrust of work began in August and is slated to be finished by year's end. During this phase of the repair project, vehicular traffic through the north portal is being severely restricted, requiring most traffic to enter the complex through the alternate South Portal entrance.

Erik Waldrip, 721st Civil Engineer Squadron project manager understands the inconvenience of using shuttles and entering through the South Portal, but said it is worth it for the long haul. When the current work is completed another, similar storms will not do the same amount of damage. A quick band aid would have been less bothersome for those working inside the mountain, but the same thing would happen in the case of another flood like the one in 2013.

"This facility will be far better prepared for another huge storm event," said Brian O'Leary, a 721st CES mechanical engineer.

Vehicle access through the North Portal was opened to vehicle traffic a few days after the rock slide, leading military and mission partners to assume the portal was up and running for good, but in mid-August of this year the portal was closed to allow final work to be completed.

Reverting to using the South Portal as the main entrance is a point of contention for some. But the amount of debris that inundated the facility and the damage it caused must be considered. Waldrip said trees about one-foot in diameter, large boulders 10 feet in diameter and tons of mud went 500 feet deep into the North Portal. For some perspective, the 7,200 cubic feet of debris in the portal area equates to about 1,500 standard dump truck loads.

Not only does the physical work of removing such a formidable debris pile take time, but so does making sure it won't happen again. Months of study was required simply trying to figure out what to do and to ascertain the degree of damage. Add on top of that efforts to determine the best methods of prevention and it can take a long time for such a project.

Assessments, geotechnical studies, designs and analysis took about 11 months, O'Leary said. After initial cost estimates were developed, contractors capable of completing the work within budget constraints had to be found. Improvements to the South Portal were needed as well, so it could handle the increased use while North Portal work was ongoing. Prior to the rock slide its primary function was as an emergency ingress to the facility.

When all is said and done improvements, repair and prevention measures will include a series of steel nets in the canyon adjacent to the North Portal to catch large debris, the paving and improvements to the South Portal, an enlarged drainage basin of at least 8,500 cubic yards, and shoring up of the roadway near the North Portal and lower parking lot.

"There was a serious debate concerning the cost benefit analysis associated with the basin capacity and the design event when measured against the physical constraints of the mountain." said Anthony Alecci 721st CES operations flight chief. There may be more work into 2016 related to parking, and NORAD Road but it will not interfere with portal access.

"Basically there is only one way in and out. That's a benefit and a challenge," Waldrip said. "We came close to losing the road and access to the upper parking lot. Protecting the infrastructure in this zone is critical to prevent erosion and get back to normal use."

Vehicle traffic through the North Portal will resume on Dec. 23. Bus pick up will remain at the current location in the parking lot as the protection-level one security screening area remains under renovation. However instead of the current 15 passenger vans traveling down NORAD Road, up South Portal Road to await clearance for the single lane traffic inside the blast tunnel there will still be a one lane traffic section, but it will be about a tenth of what it was previously. Riding the bus inside should take five to 10 minutes instead of the current 10 to 30 minutes. Pedestrian traffic will remain unchanged.

"Cheyenne Mountain Air Force Station is quickly approaching its 50th anniversary of full operational capability in April and the work that has gone into this project by 721st Mission Support Group will ensure that CMAFS will survive whatever mother nature has in store for the next 50 years and beyond," said Col. Gary Cornn, 721st MSG and CMAFS installation commander.

 

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