MK Tunnels - Buckhorn Wash, UT
The Morrison Knudsen Tunnels are located in the San Rafael Swell area of south central Utah. I first heard about this site in 1997 and it took some digging to figure out the exact location. At that time, there was no published material and the only internet reference was a cryptic posting that mentioned a military "thing" with a massive blast tunnel near the "Wedge Overlook". Mistakenly, I assumed that the Wedge Overlook was the ridge that overlooked the Utah Launch Complex. I combed the area around the complex for hours searching for some hidden tunnel. After several inquiries, I eventually found a BLM employee who was kind enough to send me a map with an X marking the spot....roughly 40 miles from where I had been searching.
What exactly are the MK Tunnels? From the Sun Advocate:
In 1948, when the United States Department of Defense was looking for naturally occurring defenses from air-delivered explosives, its search brought it to the Western flank of the San Rafael Swell. Several horizontal shafts were created, after which varying amounts of explosives were detonated above them at ground level. The relatively soft rock of the Navajo Sandstone probably didn't perform as well as the hard granite of Colorado where NORAD and other military facilities were ultimately located. There were no military installations developed here. However, the craters that resulted from the detonations, along with the prepared shafts, gained some local notoriety and have come to be known as the "MK Tunnels," taking their name from Morrison Knudsen, the contractors DOD enlisted to prepare the shafts.
Also from the Sun Advocate:
According to the records that were released later, blasts were set off ranging from a number of charges with 320 lbs. of explosives to the biggest blast that took place on or around Oct. 4, 1948 that employed 320,000 lbs. of explosives.
Officially known as Buckhorn Wash Underground Explosive Test Site #8, the site of the MK Tunnels was used by the Department of the Army as an explosive test area between 1948 and 1952. Located in Emery County, Utah, the site encompasses 1,920 acres in a geologic area known as the San Rafael Swell.
These tests were part of the Army’s Underground Explosion Test (UET) program whose purpose was to test the effects of explosive detonations on underground structures buried in soil and/or rock. This was during the height of the Cold War and the Defense Department needed to know how best to protect underground installations. The UET program sought answers to questions about the depth and type of cover needed to protect against enemy attack, the effect of repeated bombing on underground structures, ways to improve the design of tunnel openings and so forth.
Fractured rock above main tunnel.