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About is a community of practitioners of geotechnical engineering, geological engineering, engineering geology, geophysics, hydrogeology and related disciplines. We offer members and visitors the foremost collection of geo-related articles, news, and online resources to keep those geo-professionals in practice at the forefront of their respective fields.

Protestors Cause Geotechnical Work to Shutdown for Sydney WestConnex Project
GeoNews - Project Related
Written by Randy Post   
Monday, 05 October 2015 23:34
Protestors of the proposed WestConnex project

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]

Site Characterization Services: Step 3 Field Exploration
GeoNews - Available Resources
Written by Randy Post   
Monday, 05 October 2015 23:32

Another in the series of excellent videos by Terracon. This video addresses the field exploration techniques they use. [Source: Terracon YouTube Channel. Image: YouTube]

Last Updated on Tuesday, 06 October 2015 06:34
Terzaghi's Birthday 2015 and Growing Pains of a New Profession
GeoNews - Available Resources
Written by Randy Post   
Friday, 02 October 2015 05:44

Happy Karl Terzaghi's Birthday!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!

Last Updated on Friday, 02 October 2015 06:09
Dewind Remediates Seepage at Dam in Tyler, Texas
GeoNews - Project Related
Written by Randy Post   
Wednesday, 23 September 2015 22:52

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]

Last Updated on Thursday, 24 September 2015 05:55
Moretrench Remediates Dangerous Seepage Problem at Dam in Catskill Mountains
GeoNews - Project Related
Written by Randy Post   
Wednesday, 23 September 2015 22:09
Moretrench's Cannonsville Dam Project to remediate seepage encountered at the toe of the structure

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]

Texas Regulator Clears Oil And Gas Company Of Causing Quakes
GeoNews - Miscellaneous
Written by Randy Post   
Thursday, 17 September 2015 21:54
Hydraulic fracturing (fracking) wastewater injection well

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 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.
[Source: via AEG Insider. Image: Larry MacDougal/Canadian Press via AP Images via]

USBR Selects 23 Projects Totaling $5.2 Million to Build Drought Resiliency in Nine States
GeoNews - Available Resources
Written by Randy Post   
Thursday, 17 September 2015 21:52
Drought resiliency grant awarded by the USBR

From the USBR Press Release:

Bureau of Reclamation Commissioner Estevan López 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 López 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.
[Source: Read the full press release at the USBR. Image: Walnut Creek Magazine]

Site Characterization Services: Step 2 Methods Consulting
GeoNews - Available Resources
Written by Randy Post   
Sunday, 13 September 2015 23:01

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]

Last Updated on Monday, 14 September 2015 06:04
GPR Used to Locate Possible 'Superhenge' Near Stonehenge
GeoNews - Geoarchaeology
Written by Randy Post   
Sunday, 13 September 2015 23:01
Ground penetrating radar (GPR) antenna mounted on a small tractor surveying near the Stonehenge monument as part of a larger project that identified a row of 90 previously undiscovered stones less than 3 km from Stonehenge.

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]

Final three pieces of tunneling machine safely in the access pit
GeoNews - Project Related
Written by Randy Post   
Sunday, 13 September 2015 23:00
One of the final pieces of the Bertha TBM being lowered into place

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]

Tunneling machine's front end bolted in place
GeoNews - Project Related
Written by Randy Post   
Sunday, 30 August 2015 23:25

Bertha TBM cutterhead being lowered back into access shaft

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!

Time Lapse Video

[Source: WSDOT Alaskan Way Viaduct Project Page. Image: WSDOT]

Last Updated on Monday, 31 August 2015 06:29
Florida Pool Pushed Out Of Ground After Heavy Rains
GeoNews - Failures
Written by Randy Post   
Sunday, 30 August 2015 23:24
Popped pool in Holiday, Florida

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 via Image:]

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