OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT
2012 Abandoned mine Land reclamation Award
small project Award winner
Abandoned Mine Reclamation Program
Utah Division of Oil, Gas & Mining
Salt Lake City Utah
For defeating a 60 year old coal fire, for developing new techniques to fight the fires, and for the difficulty involved in accomplishing the goal, the Small Project Award was presented to the Abandoned Mine Reclamation Program, Utah Division of Oil, Gas & Mining, Salt Lake City Utah.
Workers on a steep-slope drilling pad as part of the effort to extinguish the Maclean mine fire.
Utahís Abandoned Mine Reclamation Program worked for more than 20 years to extinguish an underground mine fire that ignited in 1945. Putting out the 67-year old fire, which migrated underground, required the use of new mapping technologies as well as creating new chemical fire retardants, while working on extremely steep slopes.
The mine in question began operating in 1919, then closed in 1945, when the underground fire ignited. By the time the state program came into existence in the 1980ís, what was thought to be one fire had spread into several, with fissures, crevices, and landslides allowing oxygen in, and multiple seams of coal were burning. A full acre of land had slumped because the fire had burned away underlying coal. In addition to threatening air quality, the fire created several public safety hazards.
An example of the many crevices that formed as the fire migrated underground. Some cracks were large enough to swallow large animals.
The ground surface near the fire was prone to caving underfoot; some crevices were large enough to swallow a person or livestock. The fire also threatened to ignite forests above ground. Even though the state reclaimed the area in the mid-80ís, sealing mine portals and burying coal refuse piles, the fire raged on.
One of the biggest challenges was determining the exact location of the fires. By 2010, foot wide cracks appeared on the mountainside about 170 feet above the old mine site. Using signs on the surface proved unreliable, even using infrared photography. To determine the location, project managers drilled dozens of boreholes and modeled the data in three dimensions, then overlaid the data on traditional geologic and mine working maps. The fire affected an area that covered 400 vertical feet on very steep slopes. Creating work pads to drill the boreholes and build seals were difficult.
Workers prepare to inject fire retardant and grout into one of the crevices.
In spite of these obstacles, on May 31st, the Utah Abandoned Mine Reclamation Program declared the Maclean fire officially extinguished after three tries to put it out, in 1990, 1992, and then 20 years later. The difference, project managers say, was developing the skills to work in cramped, unstable high slope areas while applying state of the art, Utah-developed fire retardants into specific locations.
Workers had little room to work while drilling the boreholes to locate the fire, and then inject fire retardant to extinguish the fire.
Utah has about a dozen similar underground fires currently burning. The state will apply the techniques and tools developed at the Maclean fire to extinguish those fires at lower cost and in less time.
Link to Utah Division of Oil, Gas & Mining, Abandoned Mine Reclamation Program Website at http://linux1.ogm.utah.gov/WebStuff/wwwroot/