AAI drilled more than 30 holes into the Ingals & Haas Inc. (IHI) coal mine fire located near Rifle, Colorado, for a Colorado Division of Minerals and Geology (DMG) project in 1999. The IHI fire burned for more than 70 years in steeply dipping strata of the Grand Hogback prior to drilling activities. Goodson & Associates, Inc., Consulting Engineers (GAI), of Lakewood, Colorado contracted with the Colorado DMG to extinguish the fire using foam-filled cementitious grout. AAI subcontracted to GAI to provide drilling and hole completion services on the second phase of drilling.
AAI drilled into the fire using AAI’s track-mounted Aker MP5 drill rig fitted with a Longyear HW casing advancer (4½ inch diameter). A track-mounted rig was used because of its ability to tram over 1 mile to the drill site under its own power and work on the rough drill roads cut into the 45° to 65° sloping hillsides. Angled holes were drilled into the burning seam to avoid potential subsidence collapse above the outcrop. Holes were typically 40 to 70 feet long. Foam and water were used to cool the drill bits from the 550° Fahrenheit (F) to 1,700°F downhole temperatures. AAI’s crew wore special clothing and masks and maintained a gas tester on-site to protect against steam and toxic gases emitted from the fire.
The holes were completed with 3.0-inch-diameter black steel pipe, grouted with bentonite grout, and capped. GAI used the holes to successfully pump approximately 2,700 cubic yards of cementitious grout into the mine fire. The second phase project cost a total of $445,125, of which approximately one-quarter was drilling costs.