Air Force Bases

Minuteman Missile Silo Destruction

For nearly a third of the 20th century, Minuteman missiles stood sentry along the northern borders of the U.S. But with the end of the Cold War came the 1991 Strategic Arms Reduction Treaty that called for dismantling some missile sites. Omaha District has played an integral role in efforts to comply with the treaty's requirements.

In 1995 the federal Base Realignment and Closure Commission decided to empty the Minuteman III missile silos under the jurisdiction of Grand Forks Air Force Base in eastern North Dakota. The last missile was removed from its silo in June 1998 in preparation for demolishing the silos and their control facilities.

The first silo was imploded last Oct. 6 near Langdon, N.D., just a few miles from the Canadian border. Thirteen more were imploded before the demolition work was halted the ground froze.

The Corps worked with the Air Force to prepare the specifications and drawings and is currently supervising the $13,758,000 construction contract for demolishing 150 underground missile silos and 15 underground missile launch control facilities. The contract is in three phases, with each phase including 50 silos and five control facilities. The missile sites cover about 11,000 square miles, ranging from a 30-minute to a 3.5-hour drive from Grand Forks

Fiscal year 2000 (FY00) funding has been received for the second phase, and work will start this spring. The third phase is to be funded in FY01.

The completion date of the silo implosion is November 2001, as required by the treaty. All of the silos must be imploded by the date, according to Erv Fahrenkrug, Chief of ICBM Facilities Engineering of the Air Force Space Command.

"Everything seems to be moving along pretty well," said Fahrenkrug. "We're making progress." Observation and final site grading will be completed after November 2001.

Omaha District project manager Larry Bringewatt, noted that the Air Force is a repeat customer for the U.S. Army Corps of Engineers on the demolition project. "We put the package together in 1992 and 1993 when 150 missile silos were demolished at Ellsworth Air Force Base, S.D., and 150 at Whiteman Air Force Base, Mo. The Air Force was really pleased with those projects. They saw what we could do and wanted us to do it again."

The Grand Forks project was not identical to the previous projects. " Grand Forks was built later than the ones at Ellsworth, and there was an evolution of the system," Bringewatt said. "The generators were in a capsule underground, while at Ellsworth they were in a building that was partially out of the ground. The top of the silos and the lids for the silos were more heavily reinforced at Grand Forks ."

The Corps design team worked with the Air Force to find information on the facilities.

"The silos and control facilities were built in the '60s," said Tim Campbell, lead designer. "The Air Force Missile Group did a really good job of keeping as-built information. They had a lot of changes to the facilities during the years, and they had worked on keeping drawings up-to-date to show what was done. There are always some things that are different, because it's hard to keep track of so many years of modifications and changes. We collected quite a few as-built drawings and information about the sites ; it was a big part of the project."

The 150 silos are built of quarter-inch steel liner plate, which is surrounded by 14 inches of reinforced concrete. They are 12 feet in diameter and 90 feet deep. "The 15 launch control facilities are basically underground bunkers, two capsules 60 feet below grade," Bringewatt said.

One capsule had mechanical equipment, air handling equipment, and the generator, while the other was the living space with the control equipment.

"There were environmental issues since some of the sites are close to wetlands, and we made sure that we weren't impacting them," Campbell said. "Because there was living space in a one-story building above grade and in a capsule, "sewage was discharged into the lagoons. Some of the sludge had to be sampled and tested as part of the closure," although most of the lagoons were dry.

"The Air Force is probably leading the way on the environmental aspects," said Sgt. Rob Mims, Public Affairs Officer of Grand Forks Air Force Base. "We have to set the example, so we're probably leading the way as far as being environmentally sound and turning it back to nature."

Delma Stoner, Omaha District environmental engineer, noted that the sites included underground storage tanks and sewage lagoons. "They have to be in compliance with the state regulations; all the tanks at the site either are removed or stay in place, but in accordance with regulations."

Instead of removing the lagoons, they will be backfilled and tested to be sure there is no contaminant. "The main thing is to be sure that the environment is safe for someone who would take over the site." The Corps reviewed the environmental assessment.

Omaha District geologist Tim Jensen worked on requirements for closing wells, which include water wells, cathodic protection wells, and monitoring wells. "We used some cutting-edge methods," he said. "These wells were built in the '60s-'70s time frame; well construction and environments are stricter now."

The Corps awarded the $13.7 million contract to demolish the silos and launch facilities to Veit and Company, Inc., of Rogers, Mo. Subcontractors include R & N Hide and Fur for salvage, and Demteck for demolition. Bart Anderson, Veit vice president, said that one of the challenges of this project is "just the magnitude, spread out to 165 different sites across 11,000 square miles. This summer we might be working on 20 different sites all on one day."

Mark Mailander, Black Hills Area Engineer for the Omaha District, commented on the schedule. "We have a very fine-tuned operation that we've developed since we awarded it, then and now. We have the subcontractors pretty well lined out. They know what they can do and how long it takes them, and we have a pretty good idea what we need to do from here on out. Weather will play a big part in that plan. Also funding."

Blasting was discontinued in December because of frozen ground conditions. "But there is still a lot of salvage going on in the silos themselves," said Steve Hasner, Omaha District resident engineer at Grand Forks Air Force Base. "We have a contractor that has been pretty easy to work with, as well as a local missile engineering group that has been extremely cooperative and easy to work with."

"So far it seems to be working well," said Scott Rudolf, chief missile engineer. "We haven't run into anything yet that was unexpected. The contract got off to a late start because the environmental impact statement took a little longer to get signed and finished than what was programmed. So we didn't get the whole summer of 1999. But I think with the easy winter we are having they will catch up in a hurry this summer. Everything seems to be going very well."

According to Veit representative Anderson, the process in the silos includes first salvaging metal liners from the silos. Holes are then drilled into the silos and packed with about 800 pounds of explosives; then the silo is blasted.

"They move in with the heavy equipment, usually two back-hoes, and start tearing it apart," Anderson said. "They dig it out to a depth of 20 feet."

The silo with its observation cone then sits for 90 days during the observation phase required by the START treaty. During that time, the Russians can verify by technical means that it has been dismantled according to the treaty.

Don Speulda, Omaha District project office, verifies the activity and notifies the Treaty Compliance Office. According to Speulda, "these milestones or activities have a specific timeline by treaty requirements and are non-negotiable and will not be compromised for any situation."

After 90 days, "we come in and backfill it -- take all the dirt and throw it back in the hole, compact it, level it off, and spread gravel or grass seed," Anderson said.

The 110-ton silo cap is buried 10 feet below the surface in front of the destroyed silo. "The lid doesn't shatter very well, so rather than trying to shatter it, they just bury it," Bringewatt said.

Speulda described the implosion of the first silo last October. "The implosion sent chunks of concrete about 100 feet into the air. All you could hear was a muffled boom and then a grayish brown dust cloud with debris filling the air."

Campbell, who also witnessed the first silo implosion, said that the contractor drilled 66 holes into the silo and set the explosives with seven separate delays "so a certain amount would go off and then another and then another in rapid succession. By doing seven delays he limited the amount of ground shock and sound that resulted from the explosion."

In the launch facilities, the contractor salvages anything usable from the capsules, then the door is welded shut and the elevator shaft is filled. When finished, the land will be disposed through the government disposal regulations.

Some remnants may remain for future generations to view. The START treaty includes provisions for displays. Stan Rogers, natural and cultural resource planner at Grand Forks Air Force Base, said that the Grand Forks system was eligible for the Register of Historic Places based on Cold War criteria. They are developing an agreement with Grand Forks Air Force Base, Army Material Command, and Space Command with the State Historical Society of North Dakota for displaying Cold War artifact associated with the Minuteman mission in North Dakota. The exact nature of the presentation has not been determined.

Some images have been preserved, however. Mark Mailander explained that the launch control capsule that housed the personnel while they were on duty had graffiti on the walls.

"When you spend a lot of time down in the control, I guess you write on the walls or draw pictures on the walls. They had some real interesting…we'll call it artwork."

The artwork has been photographed so that it will be preserved after the capsules are sealed and inaccessible.