The warning came over a dump truck operator's radio as he and another man were working in the Pikeview Quarry pit:
"Get out of there."
In what witnesses say sounded like a jetliner and looked like cake batter being poured into a pan, 2 million tons of limestone came crashing down the stair-stepped ledges of the quarry wall in a span of about 10 seconds on Dec. 2, 2008.
A giant plume of dust erupted, the debris buried the road out of the pit, and the men were forced to abandon their machinery and scramble over the rubble to escape.
The slide, detailed in a report to the U.S. Department of Labor, is one of many in the quarry's long record of unstable terrain that raises questions about whether it's safe to build a "world class bike park" on the massive foothills scar on Colorado Springs' northwest side. That plan has become the centerpiece in a local concrete company's quid-pro-quo to build a new quarry south of Colorado Springs.
Transit Mix Concrete announced this month that it was willing to sell the Pikeview property to Colorado Springs at a discount if it's able to get permission from the state and El Paso County to mine part of the Hitch Rack Ranch off Colorado 115 near Little Turkey Creek Road.
Renderings of the bike park have generated excitement among members of the cycling community, and the El Pomar Foundation has donated $1 million to the city to help pay for the construction of the park on the quarry scar or another site.
But opponents of the proposed Hitch Rack Ranch project, who fear the new quarry could threaten local wildlife habitat and their water supply, have dismissed the bike park proposal as a fanciful public relations ploy.
The Pikeview Quarry site has what the Colorado Geological Survey has called "a history of slope failures and rockslides" dating back to the 1970s, according to a 2009 report. The site is located in an area susceptible to landslides, a map produced by the Survey shows, and has experienced slope failures as recently as 2015.
"There's so many risks involved with having a public park on any area that's unstable," said City Council President Richard Skorman, a vocal opponent of the proposed new quarry. "I wouldn't want that liability."
Engineers working for Transit Mix have told The Gazette the land will be a safe spot for a bike park once the land has been reclaimed. State regulators will ensure that the quarry is fully stabilized as part of the reclamation process before it's available to the city, an engineer said.
Only about 11 acres of the roughly 160-acre mining area have been reclaimed so far, and the cost of the entire process has been estimated to be more than $21 million, according to records filed with the Colorado Division of Reclamation, Mining and Safety. El Pomar's donation for the new park wasn't site specific, although city officials have said they would be interested in the Pikeview property if it becomes available. Foundation CEO William Hybl has said he doesn't believe the proposed bike park needs to hinge on the new quarry being approved, despite Transit Mix having repeatedly said it won't be able to end operations at Pikeview unless it has a new source of aggregate.
The foundation's $1 million pledge comes just a few weeks before the state's Mined Land Reclamation Board will decide whether to grant Transit Mix a permit for the new quarry. The board denied Transit Mix's first application at the end of 2016, citing many of the same concerns as quarry opponents. The company submitted a second application last October.
If the board approves the second application, Transit Mix will still need a permit from the county.
A rocky history
The 2008 slide, which covered nearly 15 acres and left a scarp 70 feet high, led to another slope failure the following year that sent a million tons of limestone tumbling down the quarry walls.
The state mining board found Transit Mix was at fault in the 2008 slide and issued a cease-and-desist order in June 2009, requiring that the company pay a $4,200 fine and submit a new plan to stabilize and reclaim the quarry. The board found that miners had removed rock that was serving as a buttress to a slope, which ultimately triggered the failure. Transit Mix admitted at a hearing before the board that it mined more than it should have, according to the board's order.
But it wasn't all the company's fault - the Colorado Geological Survey noted that the nature of the land also played a factor in the 2008 slide. Its report attributed the slope failure, in part, to "the inherent weakness of the rockmass" caused by "the abundant discontinuities related to the Rampart Range fault zone."
The mine wasn't declared safe until 2013.
The company says that it's moved more than 3 million tons of material from the path of the slide to the toe of the mass. It's also installed a monitoring system that records movement of the land, notifying mine operators of any impending failures. The system has not alerted Transit Mix to any dangerous conditions in at least two years, said Transit Mix aggregate production manager Brandon Heser.
The quarry experienced its latest slide following the floods of May 2015, according to an inspection report filed with the state. The Waldo Canyon fire had stripped the vegetation from the area above the quarry, exposing the walls of the mine to increased runoff, and weakening a mass of rock that miners anticipated would eventually fall.
Paul Kos, a senior geological engineer at Norwest Corporation, said the 2015 slide was a result of the 2008 incident.
Material loosened during the slides continues to settle, and the slope won't be fully stabilized for several years, said Kos, whose firm is paid by Transit Mix to monitor quarry conditions.
Transit Mix employees are still prohibited from accessing the main slide area "out of an abundance of caution," Kos said.
Issues with instability have affected quarry operations for decades, according to the Colorado Geological Survey's report. Two slides took place in the 1970s, when rock slabs 20- to 30-feet thick and hundreds of thousands of tons in size came loose. In 1993, near the area of the 2008 slide, a 25-foot thick rock slab weighing about 500,000 tons slid 400 to 500 feet down the slope.
Reclaiming the scar
The quarry's reclamation schedule suggests that it would be years before the bike park proposal could become a reality.
Transit Mix President Jerry Schnabel has said that, if the company receives the permits for the new quarry and is able to end operations at Pikeview, crews will spend about two years moving dirt before transitioning into a five-year final reclamation period, in which they'll plant vegetation and wait for the roots to take hold.
Reclamation efforts at Pikeview began in the early 2000s, when volunteers planted thousands of Douglas firs and Rocky Mountain junipers high in the mine. But much of that work - all but 11 acres - was wiped out by the 2008 slide, and not much more has been accomplished since, according to annual reports the company has filed with the state.
Transit Mix's amended plan for Pikeview states that reclamation is expected to cost more than $21 million, although Kos said the company has found ways to reduce that cost.
Generally, reclamation of Colorado mines takes about five years, although it can take longer if erosion causes issues or the vegetation doesn't grow properly, said Todd Hartman, a spokesman for the Division of Reclamation, Mining and Safety. That reclamation work must include "geotechnical work that provides slope stability at the site," Hartman said.
Transit Mix's bond - which totals about $4.2 million - won't be released until the division deems that reclamation has been complete, he said.
Contact Rachel Riley: 636-0108