Second Gold Hill Mesa expansion on hold as geologists ask for more testing
The Colorado Geological Survey is withholding its recommendation for approval of a second development phase at Gold Hill Mesa, where 55 single-family lots are planned on nearly 9 acres.
The survey’s report calls into question the stability of the site’s northeast slope, in addition to existing concerns of settlement and liquefaction. Without additional testing, construction at the second plot above the century-old mine tailings pile isn’t recommended, the document says.
The document was submitted at the request of Colorado Springs city planners and engineers who asked the state agency to examine the proposed expansion, called Filing 10.
Without further testing, the agency cannot give its consent to moving ahead with the project, says the Oct. 19 report written by Jonathan Lovekin, senior engineering geologist for the agency. The document was reviewed and approved by the agency’s director, Karen Berry, and sent on her letterhead.
Lovekin echoes concerns he expressed in recent months about another plot, Filing 11, and the development as a whole.
Considering Lovekin’s recommendations and comments, city planners and engineers have put construction at Filing 10 on hold for now.
Approval of home construction in the Filing 11 area was put on hold in April after Lovekin asked that the developer — Gold Hill Mesa — test the plot for its settlement potential. He also asked that the entire site be tested for its “liquefaction potential,” destabilization that could be set off by seismic activity from nearby faults.
Lovekin offered the same recommendations for Filing 1w0, but also called for an additional slope stability analysis.
“There are minimal records to indicate how the mill tailing slimes were placed but we know of no compelling reason to expect the tailings were placed carefully or in the type of controlled conditions that would be conducive to residential development,” Lovekin wrote of Filing 10.
Gold Hill Mesa sits on the former site of the Golden Cycle Mill, which refined ores mined in Cripple Creek from the early 1900s to 1949. Portions of the development sit atop an old decant pond full of tailings left over from that refining process. That old pond reaches an estimated 130 feet deep in places, and instability has been a chief concern since the development’s inception. Mine tailings are known for their instability and settlement potential.
Sinking soils and consequent damage to homes has been recorded at Gold Hill Mesa, Lovekin reported this year.
‘That’s their opinion’
The developer’s representatives and many residents flatly deny that there has been an inordinate amount of sinking or subsidence of land there. Rather, construction defects are responsible for any reported cracking of foundations and other damage to homes, they say.
Bill Hoffmann, the senior principal engineer for CTL Thompson, a regional engineering firm hired by the developer, said he disagrees with Lovekin’s assessment. The land is stable and safe for construction, he said.
Regarding the survey’s Filing 10 report, Hoffman said, “That’s their opinion.”
Heather Kelly, a public relations specialist hired by the developer, said at one point city staff had approved Filing 10 for construction.
“So this latest report is sort of a change in that,” Kelly said.
After a small alteration was made in the site’s development plan, city staff “kicked it back up” to the Colorado Geological Survey for examination, said Barry Brinton, development manager for Gold Hill Mesa.
Filing 10 was originally approved in 2018 before it was resubmitted to the state agency, city spokeswoman Jamie Fabos said in an email.
The vast majority of filings at Gold Hill Mesa were approved by city staff without the Colorado Geological Survey examining each individual phase. Rather, the state agency reviewed a broad proposal in 2004 and it’s upon that review that the subsequent phases were approved.
“We accepted a ‘revalidation’ report from CTL Thompson which concluded that the 2004 report was still acceptable,” Fabos said of past approvals.
Then, in early 2017, the Colorado Springs City Council unanimously passed an ordinance requiring the state agency to review site plans and make recommendations in advance of development across the city. That relatively recent ordinance is the reason state geologists reviewed filings 10 and 11 at Gold Hill Mesa and called for additional testing.
Before it was approved, Hoffmann spoke out against the ordinance in front of the Colorado Springs Planning Commission, calling it a solution looking for a problem.
The commission approved the ordinance with six members in favor, two absent and one recused. The measure then passed the City Council by unanimous vote.
Only two phases of development have been reviewed by state geologists after the ordinance was enacted and construction at both has been put on hold, pending tests.
While construction is on hold for filings 10 and 11, work can continue at already approved phases.
Asked multiple times for comment, Mayor John Suthers was “disinclined” to speak out about Gold Hill Mesa, Fabos said. She did not elaborate when asked for clarification, but instead offered a short statement from the city’s chief executive.
“Filings 10 and 11 (are) under review by the Colorado Geological Survey and city engineering,” Suthers’ statement reads. “I am confident in the abilities of the professionals involved to reach a satisfactory resolution.”
Councilman Bill Murray noted that he, other elected officials and city staff aren’t geological experts and must rely on the data they’re given before allowing additional construction anywhere in town. Now, the survey’s recommendations have called the data presented by Gold Hill Mesa into question, he said.
“We trust the information given to us, until we don’t,” Murray said. “I want to halt (construction) based on the geological survey — if that’s what they call for — for further review and I want to be situationally aware of anything and everything that impacts that entire hilltop.”
The decision of whether to approve construction at Filing 10 ultimately rests with city planners and engineers, not the council. And Murray said that staff should give weight to Lovekin’s concerns.
“After all, we’re the ones who brought them in (to examine) all this property,” he said.
Stability, erosion, settlement
Reports on Filing 10 submitted to the city by the developer “do not include a detailed subsurface investigation with sampling and testing,” Lovekin wrote. Details offered about the soils there are apparently based on “limited drilling” from one 1999 study and a 2004 seismic study.
Those reports “do not contain the information needed to demonstrate a thorough understanding of the physical and engineering properties of the tailings,” Lovekin wrote.
Hoffmann took issue with that assessment, however, and said he has completed a proper slope analysis of the site.
“I did additional slope stability analysis and addressed the items that they brought up. … I think they have reviewed it, but I don’t know that,” Hoffmann said. “They need to describe to me what more they’re after.”
Soils at Filing 10 are highly saturated, Lovekin wrote. One boring from 1999 showed a water content of 73.2% in deep silts. Above a certain saturation point, soils behave like liquids and become unstable, he has said.
And further developing Filing 10 could weigh down those soils and increase that saturation level, which could cause slope failure, Lovekin wrote.
“I will agree there are some saturated soils there, but I disagree that it’s a major concern,” Hoffmann countered. “Based on performance and some other testing that I’m in the process of working on.”
Hoffmann declined to share or characterize the results of those tests, which are not yet complete. He said the findings will eventually be discussed with state geologists.
As for performance, Hoffmann said, “We haven’t seen any issues out there. … Anywhere.”
The sensitivity of those saturated soils should be tested and analyzed, Lovekin wrote. In addition, a stability evaluation should either consider the site’s worst-case scenario or be based on site-specific drilling, sampling and testing, he wrote.
Murray previously expressed concern that the developer’s engineer, rather than an independently contracted firm, was conducting new testing. That work is under the purview of CTL Thompson and Bryant Consultants, a Denver consulting firm hired by the developer.
Drainage and erosion should also be considered, Lovekin wrote.
The silts and sands “located on the face of the tailings dam are highly erodible,” he wrote. That erosion could damage slope stability.
“It will be important that no concentrated flows be allowed to discharge down the steep dam face without adequate protection,” Lovekin wrote. “This includes discharges from downspouts, sumps or swales.”
No settlement calculations were provided for the filing either, Lovekin wrote. Nor was there discussion or analysis about consolidation rates or what plans exist should the soils shift differently than anticipated.
“CGS cannot recommend approval of Filing No. 10 until” further testing is completed to resolve unanswered questions, Lovekin wrote.
The entire site should be tested for its liquefaction potential, Lovekin has said, because liquefaction anywhere in Gold Hill Mesa could damage the filings he’s examined.
Lovekin declined to comment for this article and said he could not say whether settlement concerns expand to the developed portions of the site because city engineers and planners have not asked for his input on those areas.
Also asked whether Lovekin’s comments have implications for the rest of the site, Hoffmann responded: “I’m in the process of doing some additional analysis and what not, and I will respond to CGS’ comments when I get everything done.”
It’s too early to say what work might be done on Filing 10, Kelly, the public relations specialist, said.
Additional testing is underway at Filing 11, Hoffmann said. Crews are conducting settlement and liquefaction analyses there.
Although Lovekin’s recommendations are to test all of Gold Hill Mesa for its liquefaction potential, Hoffmann would only confirm that he’s testing Filing 11. Asked whether he’ll test the entire site as recommended, he said, “I’ll think about it.”
Past reports and the future
Speaking on the condition of anonymity, some residents have told The Gazette that they fear retribution by the developer and neighbors if they voice concerns about homes or issues being raised by state geologists and others.
Several geologic experts have called for the entire site to be tested for its settlement potential, rather than the two phases recommended by Lovekin. Reports of damage might be sporadic now, but more problems might show up, those experts say.
Lovekin’s most recent recommendations come as the developer has hosted a private series of informational seminars about the land for residents.
“We are diligently working to address the questions CGS has raised, perform additional testing, and are prepared, as we always have been, to take all necessary actions with each step of the development to ensure the safety and stability of our community,” Stephanie Edwards, executive vice president for the developer, wrote to residents last month, responding to The Gazette’s coverage.
Edwards then turned her focus to an analysis which stacked 162 images captured by satellite cameras and concluded that portions of Gold Hill Mesa sank a cumulative 3 inches over a six-year period.
Save for an area fraught with slow-moving landslides on the city’s west side, that movement is greater than could be measured throughout the rest of Colorado Springs, Lovekin previously told The Gazette. And it’s concerning enough to warrant additional investigations of the mine tailings pile.
The satellite analysis was completed by the University of Rome. Edwards questioned the accuracy of that study.
Hayden Fischer, chief technical officer of Bryant Consultants, the Denver firm, said Gold Hill Mesa’s additional tests at Filing 11 should be complete before the end of the year and then the developer will communicate with the city and state geologists as to how to move forward.
Looking out over Gold Hill Mesa, a housing development in Colorado Springs.
An excavator moves rocks and dirt on Friday, Oct. 25, 2019, below the Gold Hill Mesa housing development at the former site of the Golden Cycle Mill, which refined ores mined in Cripple Creek from the early 1900s to 1949. (The Gazette, Christian Murdock)