The silos and silo electronic rooms "that sustained water intrusion at Fort Greely last June because of massive rainfall were all under construction and did not have any interceptors installed," the MDA told UPI.

The MDA refuted claims by the Project on Government Oversight last week that up to 25 percent of of the deployed GBI interceptors were rendered inoperable by the rains.

"All of the 18 completed silos at Fort Greely, including the silos containing flight-ready interceptors, had no water intrusion at all and were sealed tight, as per their design, and even the silos under construction sustained no structural or mechanical damage from the water," the MDA said.

"The reason the electronics equipment in the silo interface vault -- the SIV -- were damaged is because the SIV is delivered to the construction site as a pre-fabricated unit with the electronics already installed. This saves a great deal of money vs sending technicians to Alaska to hand-install each piece of equipment. This was an unfortunate incident, but Mother Nature sometimes knocks you for a loop," the MDA said.

"The rainfall last June was the highest daily rainfall ever recorded at the installation, which has been a military post since the 1940s. There were more than 6 inches of rain in just a few days in a location that gets approximately 11 inches of rain per year," it said.

Ironically, the high state of alert and readiness of the deployed interceptors at the time contirbuted to the problems caused by rain in the construction of the new silos, the MDA said.

"The fact is, the interceptors at Fort Greely at that time were on a high state of alert -- with no degradation of capability whatsoever because of the rain -- and so construction personnel were not permitted onto the silo construction site because of the danger that would be involved if the interceptors had to be launched at a moments notice if the North Korean missile had threatened the United States after it was launched," the agency said.

In an earlier statement responding to the Project for Government Accountability claims, the MDA noted that since the construction of the ABM interceptor fields began at Fort Greely in 2001, "rain had not been a problem for the Ground-Based Midcourse Defense (GMD) program due to a very low water table (over 200 feet deep) and the very high porosity of the glacial gravel."

In the June 2006 heavy rains, "although there was no mechanical or structural damage to the missile silos under construction, the unusual heavy pattern and rate of rainfall caused water to enter into seven SIVs (prefabricated underground rooms adjoining the missile silos that house factory-installed electronics) through the incomplete underground drainage and conduit systems. Due to reliability concerns caused by water, water vapor, or condensation exposure, 40 percent to 70 percent of the electronics modules are being replaced in the seven SIVs at an estimated cost of $38 million."

"Due to the subterranean entry of water into the SIVs, the false floor (covering the bottom 4 inches of the SIV), and the lack of power to the SIVs at that point in construction (preventing permanent lighting and water intrusion alarms from being operational), the initial water intrusion into the silos would have been difficult to spot during the typical 10-hour daily construction shift, and it would not have been detected at night," the MDA said.

"The initial rains subsided on 24 June. An alarm indicated water in a utility access port that was complete but had power. Construction crews removed the water and checked a representative silo (#306) under construction and saw no evidence of water intrusion. The rain resumed on 26 June, and when alarms again indicated more water in the utility access port, construction crews discovered all seven silos under construction had significant water intrusion," the agency said.

"Due to the subterranean entry of water and lack of visibility of the hydrostatic pressure and water table fluctuations during this unprecedented rain period, the date of initial entry of water into the silos is unknown," it said.

"If the initial water intrusion were spotted, it is likely that much of the factory installed SIV electronics would still have to be replaced, due to the inability to stop the flow of water through not yet completed subterranean drainage and conduit systems. The sensitive electronic modules are highly susceptible to water damage. Earthwork with heavy construction equipment to prevent pooling of water above the silos may have mitigated the flow of water, but not prevented the hydrostatic pressure and rising water table that caused water to enter all seven SIVs through the drainage systems. Pouring asphalt to prevent ground seepage was also not feasible during the rain and would have taken many days to complete," the MDA said.

"The unusually high rainfall at FGA in June 2006 revealed a vulnerability of the prefabricated SIV and missile silo construction process. The configurations of the SIVs have been changed to include water flow valves in the underground drainage and conduit entry points to prevent water intrusion in the future," the agency said. "Additionally, interim remote sensor water alarms have been activated until permanent power is installed at each silo," it said.

Also, POGO said the GBIs cost $9 billion a year. However, the MDA pointed out that is its total annual budget for all missile defense research, development, testing, acquisition. The budget for Fiscal Year 2007 as appropriated by Congress, shows the GBI element as about $2.5 billion.

Email This Article

Related Links
Learn about missile defense at SpaceWar.com