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Police were called out to one geotechnical investigation site in metro Sydney, Australia last week after residents unhappy with the proposed WestConnex project entered the work site. The crew abandoned drilling tools and equipment on the site, an apartment complex. WestConnex geotechnical contractors canceled another planned investigation as well based on the public reaction. Residents of the apartments were notified in advance of the work, and WestConnex indicated that the proper permission for drilling had been obtained from property owners and/or apartment complex management. But there is clearly a very vocal group of opponents to the project that would link the congested M4 motorway to Sydney Airport and Botany Bay. [Source: Read more about the protests in the Daily Telegraph. Image: Daily Telegraph]
Today is the anniversary of Karl Terzaghi's birthday. I have a tradition of marking the anniversary by sharing a quote or some other piece of info I've learned about the man we commonly refer to as the father of soil mechanics and geotechnical engineering. This year I marked the occasion a day early by arranging for geotechnical engineers in my office of Golder Associates to watch a video over our lunch hour by The GBA from 1988 of a presentation given by Ralph Peck entitled "Growing Pains of a New Profession - Soil Mechanics 1925-1940".
It's always remarkable to me to think that we are only one generation, or at most two, removed from the men like Terzaghi that developed the theories and practices that form the foundation for our profession. Although Peck's presentation did not focus on Terzaghi entirely, he did note that in his opinion, there were three factors that marked the transition to what we know as modern soil mechanics in the United States.
The first of these was Terzaghi's establishment of the principles of the new science: the mathematical theory of consolidation and the acompanying recognition of effective stress, the deformation conditions controlling earth pressure, and the determination of numerical values for the pertinent physical properties of earth materials.
Peck discusses the contributions of many other names, some that I had heard of, a number that I wasn't as familiar with, and talks about some of the controversies, personality clashes and egos in the early soil mechanics community. I recommend the video, or at least Peck's paper, to anyone interested in geotechnical engineering. If your firm is a GBA member, you can get either for free (just create a free login at the GBA homepage, instructions for getting the video for free on Vimeo are listed in the description of the video). Happy KTB everyone!
Dewind One Pass was involved in constructing a cut-off wall to address seepage issues at Tyler Dam in Tyler, Texas. The earthen dam was constructed of clay, but the foundation soil consisted of a very permeable silty sand material. The remediation involved a mixed-in-place soil, cement, and bentonite cutoff wall on the downstream face of the dam, about halfway between the crest and the toe. Dewind won the job, and the City's consulting geotechnical engineer narrates this video explaining everything about the project and gives them very glowing reviews. It is well worth your time to watch! [Source: Dewind YouTube Channel. Image: YouTube]
Moretrench was contacted by NYCDEP after turbid water was noticed seeping from the toe of their Cannonsville Reservoir Dam, in the Catskill Mountains. The problem was determined to be related to an exploratory borehole conducted for a hydroelectric plant project that intercepted an artesian aquifer in the underlying glacial till. Moretrench first installed a series of wells to dewater the artesian unit using the Sonic drilling method. Once the artesian aquifer was depressurized, the owner was able to stop their reservoir draw down and Moretrench was able to grout the borehole to seal off the aquifer. As a geotechnical engineer, my take-away from this project is the dangers of creating very serious problems when drilling exploratory holes around an active dam if your boreholes are not properly abandoned. [Source: Read More about the project at Moretrench. Image: Moretrench]
The Texas Railroad Commission issued preliminary findings saying that the hydraulic fracturing wastewater injection well operated by an Exxon Mobil subsidiary was not to blame for earthquakes that shook Reno, Texas in 2013 and 2014. From the Manufacturing.net article:
Commission investigators concluded that a well where Exxon Mobil subsidiary XTO Energy pumps millions of gallons of the wastewater likely didn't cause the quakes, but also said there wasn't enough evidence to demonstrate the earthquakes were naturally occurring. Parties have 15 days to respond.
Bureau of Reclamation Commissioner Estevan LÃ³pez has announced the selection of 23 projects to receive grants totaling $5.2 million for proactive drought planning and other efforts to build long-term drought resiliency in nine states in the West."The western United States has faced an unprecedented drought this year and will face many more water challenges in the future," Commissioner LÃ³pez said. "This funding will help the selected communities prepare for future droughts."Through a competitive process, Reclamation selected 12 drought resiliency projects and 11 drought contingency planning projects in the states of Arizona, California, Colorado, Idaho, Nevada, Oklahoma, Oregon, Texas and Washington.
The second in a series of videos by Terracon on the various steps of site characterization. If you are someone new to geotechnical engineering, these videos are a great overview of what we do! [Source: Terracon YouTube Channel. Image: YouTube]
Archaeologists using high-resolution ground penetrating radar (GPR) have located a massive collection of stones less than 3 km from the well-known Stonehenge site. This grouping of 90 stones, up to 4.5 meters tall (14.7 feet) have apparently been pushed over and buried. Renderings of the site have been created showing what the row of stones would have looked like. The exact purpose and how this site relates to Stonehenge is still a mystery. [Source: Read the source article at CNN. Image: Ludwig Boltzmann Institute via CNN]
The repaired cutterhead has been in the pit several weeks now, and the final three pieces of shielding for the Bertha TBM have been lowered into the access pit. Seattle Tunnel Partners team members will complete the reassembly of the machine, and manufacturer Hitachi Zosen will conduct a series of tests to make sure the TBM is fit to resume tunneling. The most recent STP schedule indicates they expect to resume tunnel boring in the later part of November. [Source: Alaskan Way Viaduct WSDOT. Image: WSDOT]
The troubled Alaska Way Viaduct Replacement Tunnel TBM known as Bertha has reached a milestone in its repair. The front cutterhead has been repaired, and has been lowered back into the access shaft to be re-attached to the TBM. The time-lapse video below shows the cutterhead being lowered down into the access shaft. What caught my eye was the number of steel cables on the crane blocks...that's a heavy lift!
The source website is calling this some kind of 'reverse sinkhole', which is definitely not the case. The article says there was a period of very heavy rain for about 11 days before this happened, with some areas seeing rainfall intensity up to 6.7 inches in 12 hours. It sounds like the water table rose to very close to the surface and buoyant forces pushed the pool out. The building inspector called it a 'popped pool'. [Source: Go see a video of this poor homeowners's pool at Weathernetwork.com via Geoengineer.org. Image: WFLA.com]