PROJECTS

Colorado School of Mines Mine Subsidence Remediation

CLIENT Colorado School of Mines

Location Golden, CO

The western portion of the Colorado School of Mines (CSM) campus is underlain by historic clay and coal mining pits (stopes).

Underground clay and coal mining also occurred in the area.  Previous investigation found up to 50-foot thick backfill in the pits, with several low-strength zones.

In 2004, a sinkhole developed in West Campus Drive where the street passes near or over the old mine workings.  A year later, a sinkhole reoccurred in the same area, along with two smaller subsidence openings in an adjacent athletic field.  In addition, some settlement was observed both in a newly constructed retaining wall supporting West Campus Drive and in a storm sewer under the roadway.

Following the second subsidence event, CSM retained Shannon & Wilson to develop an approach and specifications for emergency repair of the sinkhole using compaction grouting techniques.  We also assisted CSM personnel with a pre-bid site meeting and contractor screening, and provided construction monitoring during the compaction grouting activities.  A total of 63 holes ranging in depth from 14 to 86 feet required compaction grouting.

KEY PERSONNEL

David Asunskis
Engineer

Gregory Fischer
Senior Vice President & Denver Office Manager

Matt Grizzell
Senior Engineering Geologist

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