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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]
Plaintiffs whose homes were destroyed by the Yeager Airport Landslide in March of 2015 filed a suit naming Central Regional West Virginia Airport Authority and Triad Engineering as well as several others. The CRWVAA and Triad have filed answers to the complaint, and two other plaintiff have filed motions to dismiss themselves from the lawsuit according the the West Virginia Record. Apparently Triad was monitoring the mechanically stabilized earth retention structure as far back as 2013 when cracks were observed. In July of 2014, 28 monitoring points were installed. According to the complaint, every one of the 28 indicated movement between July and August of 2014. That strikes me as odd. Why no mention of movement after that point? Maybe there is more in the actual complaint, but having done that type of monitoring before, I wonder if there were survey issues? I think one take-away here for me is to put some monitoring points outside the potential zone of movement so you can verify that your measurements are accurate. At any rate, the article describes what Triad and the Airport Authority Board knew or didn't know. This is interesting to me, but there is a lot of legal jargon in the article. So if you have any additional interpretations of what it says, let me know with a comment below! [Source: Read more in the West Virginia Record. Image: West Virginia Record]
How would you feel if you were subjected to 75Gs of centrifugal force? Well, at least you would know what the soil feels like in some of the cutting edge geotechnical modeling being done at the UC Davis Center for Geotechnical Modeling (CGM). This article is a fascinating overview of the history of the lab, and the types of geotechnical experiments they can run using the 9 meter radius centrifuge. It can spin a 5-ton payload at 90 revolutions per minute! No other lab in the world can boast those numbers. [Source: Read the full blog post from the College of Engineering at UC Davis. Image: UC Davis]
Modified from the YouTube description: Video of a DeWind One-Pass Trencher installing a Soil-Bentonite Wall 55' deep. This is a mix in place technology capable of installations up to 125' feet deep. The soils are evenly homogenized with the additives from top to bottom and from start to finish. An Average of 300 LF installed per day. No messy mixing ponds, open excavations, very little spoils, One piece of equipment and only 4 men are required for this 5000 LF installation reducing safety exposure.