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Flooding and erosive flows following a 2004 rainstorm caused this bridge collapse in El Paso County. East Sand Creek had been

Hazards, Water

November 11, 2022

Case study: Fluvial Hazard Zone

“The Fluvial Hazard Zone (FHZ) is defined as the area a stream has occupied in recent history, may occupy, or may physically influence as it stores and transports water, sediment, and debris.” The CGS often collaborates with local, state, and federal agencies on projects concerning emergency preparedness and community…

Hazards

February 10, 2011

Hazardous Soils in Colorado

This educational video, produced in 2011, explores the various problems that arise from hazardous soil conditions — expansive, collapsible/compressible,  hydrocompactive, dispersive, swelling/expansible — across the state. These geologic hazards combined cause more infrastructure damage in Colorado than any others. The video also covers the types of damage, methods for prevention…

Retaining wall settlement at the center of the image with the sorority houses in the background and the IM field in the foreground. Photo credit: T. C. Wait for the CGS.|The Rockwell clay mine area immediately south of the CSM campus along US 6 in 1977 before more recent reclamation as a golf course. The green area to the top left is part of the IM field where the subsidence occurred. Photo credit: Colorado Geological Survey.|DC resistivity survey crew from the engineering firm Zapata/Blackhawk laying out the multicore switch cables across the IM field area in 2008. Photo credit: T. C. Wait for the CGS.|Subsidence road damage near one of the sorority houses at CSM in August 2005. Photo credit: T. C. Wait for the CGS.|A drill-rig preparing boreholes for subsurface grouting under the IM field in August 2005. Photo credit: T. C. Wait for the CGS.|One of the several subsidence features in the IM field at the Colorado School of Mines in 2005. Photo credit: T. C. Wait for the CGS.|Figure from DC resistivity report from 2009 detailing some of the infrastructure

Geology, Hazards

April 26, 2005

Case Study: mine subsidence, CSM

For decades, the west side of the Colorado School of Mines (CSM) main campus had subsidence issues related to historical mining activities. At one point, in the 1990s, one of the married student housing units in that area was so badly damaged that it was condemned.  In the early…

A precarious rock above Manitou Springs started to move in 1995 after a period of wet weather. As an emergency measure

Hazards

June 20, 1995

Case Study: Rockfall – Manitou Springs

[ED: This report from 1995 was written by Jon White, (Senior Engineering Geologist, Emeritus). It looks at a specific rockfall situation in the central Front Range town. ] Manitou Springs occupies a narrow valley where Fountain Creek emerges from the foothills northeast of Pikes Peak and west of Colorado Springs. The valley slopes are composed of interbedded resistant sandstone and conglomerates (i.e., gravelly sandstone), and weaker mudstones and shale. The outc...