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LED Fluorescence Detectors and Fuel Fluorescence Detection (FFD)

Hydrocarbons: including gasoline, kerosene, diesel fuel, jet fuel, lubricating and hydraulic oils, and tars and asphalts contain Polycyclic Aromatic Hydrocarbons (PAH’s). Polycyclic Aromatic Hydrocarbons (PAH’s) distributed in soils and groundwater fluoresce when irradiated by ultraviolet light. Because different types of PAHs fluoresce at different wavelengths, each has its own fluorescence signature. Using an instrument that measures the intensity and wavelength of the fluoresced hydrocarbon enables the assessment of the hydrocarbons present. This makes UV Fluorescence a useful technology to use in characterizing surface, subsurface and groundwater hydrocarbon contamination. We call this Fuel Fluorescence Detection (FFD). What's the right fluorescence detector for you? Using handheld UV lights enables site technicians to establish the nature and distribution of contamination above ground. For surface spills such as what gathers along a shoreline or for surface based operations such as above ground tanks and pipes, this can be a useful place to start. For underground storage tanks a useful way to begin site characterization is with a subsurface probe. Engineers trying to establish the limits of the ‘plume’ or the depth of the contaminant as it travels underground. Plumes will extend outward, downward and upward depending upon factors such as the flow of groundwater and the confining layers of clay and rock. Leveraging the ability to generate and measure fluorescence underground requires a step up in technology. In the case of CPT, a UV light source is placed in the cone itself. Fiber-optic cables transmit the resulting fluorescence to the surface where the intensity and wavelength can be measured. Because of the efficiency of CPT, large and complex sites can be characterized quickly and efficiently. The data logs are available immediately to influence critical decision-making which can help to manage costs in the long term. For instance monitoring wells may need to be installed [...]

By smadi66|December 5th, 2019|Geotechnical Wisconsin, Geotechnical Wyoming, Geotechnical Alabama, Geotechnical Connecticut, Geotechnical West Virginia, Introductory, Soil Testing, Geotechnical Arizona, Geotechnical Arkansas, Geotechnical California, Geotechnical Colorado, Geotechnical Washington|0 Comments

Ensuring That Your CPT Data is Correctly Reported and Interpreted

It is important to understand when interpreting CPT data the physics of how the data is produced. This will lead to a better appreciation of where CPT data should be validated with other types of tests in order to ensure that it is being correctly reported and interpreted. In CPT (Cone Penetration Testing), when the tip of the cone is being advanced, there is pressure exerted on the tip itself. This pressure is created from the resistance to downward force by whatever soil is resisting on the cone tip. However, this pressure is not simply exerted from the ground immediately in front of the tip. Rather, the cone forces the ground immediately in front of it to compress. This compression forces the ground in front of it to 'fail' that is, the soil cohesion is not sufficient to resist the tip load, and the soil compresses further down or moves out of the way down, sideways or a little bit away from the cone itself, upwards. Because of this movement and compression, the pressure exerted back on the cone tip is generated from a large area of soil below, around and a bit behind the cone tip itself. This means depending on soil stratification that the instruments in the tip sense soil resistance from around 5 or more cone diameters ahead and around the tip of the cone. Using a cone of 1.5 inches in diameter means that you are actually taking an average cone resistance measurement. This is sometimes called a 'tip influence zone'. If you are pushing through a sub-surface feature, such as a landslide slip face or a layer of softer clay that is a foot or less, it is quite possible to miss this feature entirely. In engineering speak, you might read something like 'exercise caution [...]

By smadi66|December 5th, 2019|Geotechnical West Virginia, Cone Penetration, Soil Testing, Experienced, Geotechnical Arizona, Geotechnical Arkansas, Geotechnical California, Geotechnical Colorado, Geotechnical Wisconsin, Geotechnical Delaware, Geotechnical Alabama, Geotechnical Wyoming, Geotechnical Connecticut|0 Comments

CPT Case Study: GEI Consultants

30 years of Cone Penetration Testing with GEI We're proud of the relationship we have with our long time customers. We succeed together. One of these groups is GEI Consultants, which has been delivering engineering services around the globe since 1970. Sean Brady, Senior Instrumentation Specialist with GEI, provided CPT University with background on their operation as it pertains to their CPT efforts. Briefly describe GEI’s engineering focus. What do you do for whom? GEI is a medium size engineering firm with around 700 employees in the United States. Our business line within GEI is Geo-technical, non-destructive testing, and geophysics. Our engineering’s have designed over 75% of downtown Chicago’s foundations and most of the tallest buildings in the world. We often are part of the design team when difficult and challenging soils are encountered. We perform CPT’s on earthen dams/embankments, river sediment depths, USCOE projects from Ft. Peck Montana to New York, RR alignments, bridge embankments, and Power plants. A little of everything you can imagine from Water, RR bridges, Landfills, stability of tail basins for the mines. We also oversee other companies performing CPT. We just worked in Asantana, Kazahkstan overseeing a new energy exposition 2016 project for both SPT’s and CPT. Also have overseen CPT testing in Doha, Qatar. When did CPT first become of interest and why? We have over 30 years of CPT testing experience. In the late 80’s we purchased a 30T CPT truck and traveled around the US performing CPT on challenging geo-technical projects. In the mid-90’s we sold our truck and started to perform CPT testing behind drill rigs. At the time we had a fleet of 18 drill rigs from track mounted, ATV, truck mounted, Barge mounted, etc. We get involved with delicate soils all the time. In some cases even when [...]

By smadi66|December 4th, 2019|Geotechnical West Virginia, Vertek Partners, Geotechnical Texas, Geotechnical Utah, Geotechnical Vermont, Geotechnical Virginia, Geotechnical Washington, Geotechnical Wyoming, Geotechnical Tennessee, Geotechnical Wisconsin, Geotechnical Alabama|0 Comments

Cone Penetrometer Testing via Speed Lock Rods

The strongest direct push rods in cone penetration testing. Unsurpassed Joint Strength Vertek manufactures a full line of CPT push rods with our proprietary Speed Lock dual-lead thread design. Speed Lock Rods provide unsurpassed joint strength, up to 50% stronger than industry standard V-threads. Our unique rope thread design uses less of the available wall thickness and balances the strength between the male and female thread ends. Speed Lock coupled joint achieves nearly 90% of the strength of the heat treated rod stock. Increase Speed, Reduce Operator Fatigue Our dual-lead thread provides fast coupling; 2.5 turns to couple or uncouple compared with 5-7 turns for competitor’s rods improving worksite productivity. Flexibility and Adaptability to Variety of Cones Speed Lock Rods are available in standard 1.44” and 1.75” diameters. Custom sizes include 2”, 2.25” and 2.5”. Vertek also manufactures custom adapters to permit use of our advanced thread design with your current inventory of CPT equipment. Make the most of your CPT rig and cone penetrometer testing equipment with Vertek Speed Lock Rods!

By smadi66|December 4th, 2019|Experienced, Geotechnical Arizona, Geotechnical Arkansas, Geotechnical Utah, Geotechnical Vermont, Geotechnical Virginia, Geotechnical Washington, Geotechnical Wyoming, Geotechnical Wisconsin, Geotechnical Alabama, Geotechnical West Virginia|0 Comments

The Application of Dynamic Cone Penetration Testing (DCPT)

Assessing the level of compaction of sub-surface soils can be essential to designing and building structures, particularly those subject to transient or cycling loads. A perfect example is roadways. If the soil beneath a roadway is not compacted sufficiently, then over time the cycling loads of passing traffic will compact the soil further, leading to surface failure such as large cracks, potholes and displaced pavement. Assessing the compaction of non-cohesive soils such as fine sands is a difficult challenge. As we've noted in other blog posts, removing a sample from the ground and sending it to a lab is not only time consuming and expensive, but can be highly inaccurate in non-cohesive soils because the samples by necessity are disturbed from their sub-surface condition. The Dynamic Cone Penetrometer Test (DCPT) is one of many forms of in-situ soil characteristic tests that are designed to assess soil density. It shares some characteristics of both SPT and CPT testing, which enables it to provide a useful and in the right application can deliver a complementary data set and is less expensive and troublesome than Nuclear Density testing. The Standard Penetration Test (SPT) is done by using a sample tube which has thick walls to prevent deformation during the test. To conduct a test, a borehole is drilled to a specified depth. The sample tube is driven into the bottom of the borehole using a drop hammer of a defined weight dropped a defined distance. The number of blows (N) needed to drive the sample tube 6, 12 and 18 inches is recorded. The SPT provides a rough indication of the soil density at depth. As noted in previous posts (link here), getting accurate data for soil density can be a complex challenge. SPT provides an estimate but is not as accurate as [...]

By smadi66|December 3rd, 2019|Geotechnical Arizona, Geotechnical Arkansas, Geotechnical California, Geotechnical Colorado, Geotechnical Virginia, Geotechnical Washington, Geotechnical Wyoming, Geotechnical Wisconsin, Geotechnical Alabama, Geotechnical West Virginia, Soil Testing|0 Comments

Ensure Properties are Accurate Using Sediment Cone Testing

Obtaining a representative and undisturbed sample of cohesive sedimentary soil, such as sand, is very difficult and often times impossible. Because of this, determining the properties of sandy or fine grained soils is best done in-situ, making Cone Penetration Testing (CPT) one of the best testing methods for measuring mechanical properties of sediment. Sediment Cone Testing When conducting cone testing of sediment the horizontal stress and sediment density are the most influential parameters on the cone tip resistance. The cone penetration tip resistance is influenced by the soil properties ahead and below the tip. If you're dealing with a sand layer that is less than 70 cm., it's important to consider what types of stratification it is located between. For example, if it's located between deposits of soft clay the CPT may not reach it's full value within the sand layer, meaning the relative density of the sand may be underestimated. By monitoring the CPT pore pressures, these influencers can be identified. The substantial effects of soil compressibility on CPT measurements are considered to be an advantage if they are identified correctly. Compressibility is one of the key factors to successfully determining soil properties and classifying soil types. Using CPT, relative density and friction measurements soils can be broken up into high, medium and low compressibility. By classifying sediment compressibility during cone testing you can better measure the particular sediment properties. Sand for example, originates from quartz or silica; it contains hard materials, does not have cleavage planes and is resistant to weathering. Certain sands, for example siliceous sand, contain trace portions of other minerals, like chlorite. Compared to other types of soil, the compressibility of sand is most complicated because it is dependent on several different factors, including: grain size and shape, particle crush-ability, angularity, grain mineralogy, void ratio, [...]

By smadi66|December 3rd, 2019|Experienced, Geotechnical Arizona, Geotechnical Arkansas, Geotechnical California, Geotechnical Colorado, Geotechnical Delaware, Geotechnical Wyoming, Geotechnical Wisconsin, Geotechnical Alabama, Geotechnical Connecticut, Geotechnical West Virginia|0 Comments

What to Consider Before Buying a Used CPT Rig

When faced with the prospect of a major purchase, it’s common to look into the possibility of buying used. In most circumstances, this is a perfectly valid option with a number of upsides, the most obvious of which being a lower upfront investment. However, when it comes to buying a used CPT Rig, you might be better off buying a new rig from a trusted vendor. Here’s why. Used Means Used First and foremost, Cone Penetration Testing is too important to leave up to chance. Sure, your used CPT Rig may appear in fine working order and you may have acquired it from a reputable seller, but there’s no getting around the simple fact that a used rig has a higher chance of failing than a brand new one. This point is further compounded when you consider the fact that even the best used CPT Rig dealer can’t match the expertise of a CPT Rig manufacturer. Expertise Straight from the Source When you buy a CPT Rig from Vertek CPT, you’re also getting access to our knowledgeable technical sales staff; something used CPT Rig sellers can’t offer. Additionally, in some instances, Vertek CPT will provide comprehensive training and will even accompany you to your first job site to maximize your chances of success. You can’t get that kind of service or expertise from a used CPT Rig dealer. Even if you think you have enough experience with CPT Rigs to ensure success with a used rig, though, it’s also worth noting that not every CPT Rig is right for every task. A Wide Variety of CPT Rigs If you have a broad enough knowledge base to feel comfortable buying and setting up a used CPT Rig, then you probably also know that there are many kinds of CPT Rigs. Cone [...]

By smadi66|December 3rd, 2019|Geotechnical South Carolina, Geotechnical South Dakota, Geotechnical Texas, Geotechnical Utah, Geotechnical Vermont, Geotechnical Virginia, Geotechnical Washington, Geotechnical Tennessee, Geotechnical Wisconsin, Geotechnical West Virginia, Introductory|0 Comments

Cone Penetration Testing Glossary of Terms

This brief glossary contains some of the most frequently used terms related to CPT/CPTU. These are presented in alphabetical order. CPT: Cone Prenetration Test or the act of Cone Penetration Testing. CPTU: Cone Penetration Test with pore water pressure measurement - a piezocone test. Cone: The part of the Cone penetrometer on which the end bearing is developed. Cone penetrometer: The assembly containing the cone, friction sleeve, any other sensors and measuring systems, as well as the connections to the push rods. Cone resistance: The total force acting on the cone, divided by the projected area of the cone. Corrected cone resistance: The cone resistance corrected for pore water pressure effects. Corrected sleeve friction: The sleeve friction corrected for pore water pressure effects on the ends of the friction sleeve. Data acquisition system: The system used to measure and record the measurements made by the cone penetrometer. Dissipation test: A test when the decay of the pore water pressure is monitored during a pause in penetration. Filter element: The porous element inserted into the cone penetrometer to allow transmission of the pore water pressure to the pore pressure sensor, while maintaining the correct profile of the cone penetrometer. Friction ratio: The ratio, expressed as a percentage, of the sleeve friction, to the cone resistance, both measured at the same depth. Friction reducer: A local enlargement on the push-rod surface, placed at a distance above the cone penetrometer, and provided to reduce the friction on the push rods. Friction sleeve: The section of the cone penetrometer upon which the sleeve friction is measured. Normalized cone resistance: The cone resistance expressed in a non dimensional form and taking account of stress changes in situ. Net cone resistance: The corrected cone resistance minus the vertical total stress. Net pore pressure: The meausured pore [...]

By smadi66|December 3rd, 2019|Geotechnical Texas, Geotechnical Utah, Geotechnical Vermont, Geotechnical Virginia, Geotechnical Washington, Geotechnical Tennessee, Geotechnical Wyoming, Geotechnical Wisconsin, Geotechnical Alabama, Geotechnical West Virginia, Introductory, Cone Penetration|0 Comments

What Can You Reveal Using Fluorescence Detection?

Even if you use CPT technology daily to test soil, you may not be aware of the further advantages CPT testing has to offer beyond its more commonly used or basic geotechnical functions. Take fluorescence detection, for example. Fluorescence detection records a fluorescent response to a specific excitation of automatic carbons in a chemical. This excitation is caused by an ultraviolet light source. But you're probably wondering how fluorescence detection can help you. Read on to find out! The Common Uses of Fluorescence Detection Before delving into scenarios in which fluorescence detection is useful, let's take a closer look at how it works in relation to CPT. One method of fluorescence detection is done using handheld UV lights to investigate above ground contamination. With CPT, the UV light source is placed in the cone, with fiber-optic cables transmitting resulting fluorescence to the surface where it can be measured in voltage responses. At Vertek CPT, we use LEDs and mercury lamps to generate UV light. Whether above ground or below, fluorescence detection reveals two ranges of fluorescent emissions: 280-450 nm wavelengths and wavelengths above 475 nm. The test is capable of detecting a variety of chemicals within these ranges, including: Polycyclic aromatic hydrocarbons (PAHs) Coal tars (DNAPL compounds) if mixed with compounds, like fuels Creosote sites that contain naphtalene, anthracene, BTEX and pyrene Total petroleum hydrocarbon values (TPH) as low as 100 ppm in sandy soil Fluorescence detection is also able to detect a number of contaminants, such as jet fuel, diesel, unleaded gasoline, home heating oil and motor oil. As you can imagine, this makes fluorescence detection extremely beneficial at fuel spill sites and sites with leaking storage tanks. However, if you already use CPT testing regularly, it's worth considering fluorescence detection in other scenarios to add capability and additional [...]

By smadi66|December 3rd, 2019|Geotechnical Utah, Geotechnical Vermont, Geotechnical Virginia, Geotechnical Wisconsin, Geotechnical Washington, Geotechnical Alabama, Geotechnical Wyoming, Geotechnical West Virginia, Introductory, Cone Penetration, Soil Testing, Geotechnical Arizona, Geotechnical Arkansas|0 Comments

Is a Sieve Analysis Accurate?

If you regularly use Cone Penetration Testing on the job, you probably already know that there are a number of alternative soil testing methods out there. Some of the more common procedures include the Standard Penetration Test, which has been covered before in this blog, and the sieve analysis, also known as the gradation test. Most commonly used in civil engineering, this basic soil testing method is used to assess the particle size distribution of soil and other granular material. But is sieve analysis accurate? As is the case with Standard Penetration Testing, sieve analysis can provide accurate results, but only in the right conditions or scenarios. In fact, sieve analysis can achieve optimal accuracy only if certain conditions are met. First off, sieve analysis needs a proper representative example of soil from the building site, meaning particles must be mixed well within the testing sample. The sample must also be of the right size, so it does not overload the sieve and skew the results. In terms of equipment, sieve analysis requires: Test sieves that conform to relevant standards Reliable sieve shaker and analytical balance Error-free evaluation and documentation Proper cleaning and care of equipment, especially sieves When these conditions are met, it is possible to get accurate and consistent results from sieve analysis, but only with coarse materials larger than #100 mesh. When it comes to finer materials smaller than #100 mesh, sieve analysis becomes less accurate. The reason for this is the mechanical energy used to move particles through the dry sieve can compromise particle size. Fortunately, this can be offset somewhat with wet sieve analysis as long as the testing particles aren't changed by the addition of water. Sieve testing is also less accurate for non-spherical particles as they may have trouble fitting through the mesh. [...]

By smadi66|December 2nd, 2019|Geotechnical Virginia, Geotechnical Washington, Geotechnical Wisconsin, Geotechnical Wyoming, Geotechnical Alabama, Geotechnical West Virginia, Introductory, Soil Testing, Geotechnical Arizona, Geotechnical Arkansas, Geotechnical California, Geotechnical Colorado|0 Comments