Destruction from the collapse of a subway tunnel in Cologne, Germany which swallowed Cologne's Historical Archive

Subway Tunnel Collapse in Cologne Germany

Destruction from the collapse of a subway tunnel in Cologne, Germany which swallowed Cologne's Historical ArchiveEarly indications are that a collapse of a subway tunnel station still under construction was to blame for the sinkhole that destroyed Cologne’s Historical Archive, home to documents dating back to 922 A.D. More info after the break. (Photo by DPA via Spiegel Online)


Pine Hills Sinkhole, Pine Hills, Florida, 2002
Project Related

Video: The Pine Hills Sinkhole – Central Florida, 2002

Pine Hills Sinkhole, Pine Hills, Florida, 2002On June 11, 2002, a 150-foot wide and 60-foot deep sinkhole opened up in Pine Hills, Florida and came within a few feet of two 3-story appartment buildings. Geotechnical and Environmental Consultants (GEC) was contacted by the owner of the site to design emergency temporary and permanent stabilization measures to protect the buildings. The sinkhole mitigation began with a chemical stabilization of the soil using an injected sodium silicate chemical grout (incidentally, that work was performed by John N. Puder, Inc., recently acquired by Moretrench) to stabilize the sands underneath the buildings and adjacent to the sinkhole. After some GPR surveys, borings and other investigations, final sinkhole repair consisted of a 200-foot long wall omprised of interlocked 36-inch diameter steel tubular piles that extended to a depth of 50 feet. They were driven by Giken America Corp. using the press-in method which helped to avoid damage to the adjacent buildings. The entire stabilization was completed within 1-month of the initial sinkhole collapse! Click through for this fascinating video. (Photo credit Giken America Corp. by way of GEC)


Sinkhole in Karst Topography being used as a drainage structure
Journal Article Reviews

Mitigation of Karst and Sinkholes for New Hospital Structure

Sinkhole in Karst Topography being used as a drainage structureThe site for the new Harrison County Hospital, approximately 25-miles west of Louisville, Kentucky had 15 sinkholes formed by limestone dissolution, a geomorphologic process referred to as Karst topography.  There were a number of geotechnical engineering and geological engineering challenges associated with the characterization, excavation, backfilling, foundation engineering and other mitigation measures as described by Peggy Hagerty Duffy, P.E. in her article entitled “Karst and Complications” in the August 2008 issue of Civil Engineering Magazine (Duffy, 2008b).

Mitigation measures for the sinkholes included use of graded filters with geotextiles, careful inspection of rock socket foundations along with pilot holes and careful geotechnical inspection throughout the construction process. One particularly interesting aspect of the project is that several of the sinkholes were used as drainage facilities to receive surface water runoff. Read on for a summary of this interesting article. (Photo of sinkhole in Karst Topography being used as a drainage feature, from Duffy (2008b), Civil Engineering Magazine)



Johannasburg Sinkhole Opens after Tunnel Collapse

A 12m long sinkhole opened up on Oxford Road in northern Johannesburg South Africa after a partial tunnel collapse in the Gautrain rail tunnel being constructed underneath the road. Eyewitness accounts say there was a broken water pipe flooding the sinkhole, but no word on which occurred first. The road is expected to be closed for 2 weeks. Gautrain representatives said the tunneling would resume after geotechnical/geological investigations into the collapse are completed, which could take "several weeks". (Photo credit: Werner Beukes, Sapa via

Via The Star (Zambia) and (Johannesburg?)



7 Amazing Holes

A colleague of mine (thanks Jamie!) sent me an email with this intriguing title. I have no idea where it originated, but it is an interesting compilation of some amazing photos and short descriptions of various natural and man-made "holes". A few sinkholes, glory holes, and of course open pit mines. By the way I didn’t write (or edit) this, just some minor formatting updates. Check it out. 



City of Vancouver sues over failed shoring

The City of Vancouver is suing a developer, excavation contractor and their consulting engineer for the costs of repairs, overtime for city employees and lost revenue from parking meters etc stemming from an apparent failure of a shoring system that formed a 30-meter sinkhole. No mention of the developer’s name or the engineer, but the contractor was Matcon Excavation and Shoring. The site will be the future home of high-rise condominiums…if the City lifts it’s stop work order.

The failure of the shoring caused a break inf a 20-cm water main ultimately flooding the site. It also necessitated the closure of the adjacent street. Of course this invites the whole chicken or the egg scenario. The defendants will probably argue that the water line failed first causing the failure of the shoring, but of course the City Engineer, Tom Timm was not shy about fingering the shoring as being deficient.

"It’s some kind of a failure of the shoring system . . . either a design issue or the way it was put in place."