Screening for Soil Contamination Levels with CPT

Expanding from geotechnical Cone Penetration Test (CPT) into other services is a great way to grow your business. Evaluating subsurface soil contamination provides many business opportunities and a way to differentiate yourself from other CPT service providers – allowing you to protect your business, while expanding into new regions and adding clients. In many instances, the existence of environmental contaminations in an area is known, but the question that needs to be answered is, “where is it”? In other posts, we explain how CPT works, and how it can be used to characterize the strata underground hundreds of feet deep, depending upon the actual subsurface conditions, the equipment being used etc., In addition to identifying soil types by layer and depth, geo-technical CPT testing also helps to establish groundwater levels and potential migration pathways. This makes it useful for identifying where contamination may migrate or be confined. Establishing a depth profile of the contamination underground and how the ‘plume’ is located and migrated, or where it is likely to expand in the future is vital to establishing a cleanup or remediation plan. Once contamination has been shown to be likely, our discrete soil and ground water sampling equipment delivers physical samples for confirmation. Once CPT became well-established and proven as a geo-technical evaluation tool, it was natural to try and see what other types of testing could be accomplished using the same tools. In addition to mapping groundwater conditions with in-situ pore pressure transducers, CPT tools that sense the direct presence of various types of hydrocarbons and other volatile organic compounds at depth are now available. A variety of cone sensors can be used to test for specific types of contamination. Multiple CPT equipment modules can be configured with multiple sensors, including soil moisture resistivity, video, radiation and sensing for [...]

Hollow Stem Augers Don’t Provide the Accuracy that CPT has to Offer

Geo-technical Boring is less accurate, less efficient and more expensive than Cone Penetration Testing (CPT), here's why. When it comes to selecting a method for subsurface investigation and testing you are presented with different options. From the Standard Penetration Test (SPT), which is a type of Geo-technical Soil Boring to Cone Penetration Testing (CPT) there are many options to consider, and each provides certain advantages over the other. Today we’re going to compare Geo-technical Boring to CPT. Geo-technical boring is a method of drilling which is performed for site investigation. This drilling technique is most commonly used to obtain information on the physical properties of soil and rock under a foundation. This information helps to determine the depth of the foundation, ensure the site is safe and determines if structural compensations will be needed. This also ensures that the foundation, caissons and various supports are built in the right place. Hollow Stem Augers One type of geo-technical boring using a hollow stem auger is the Standard Penetration Test. Like it's name suggests, a hollow stem auger is a drilling tool that enables you to capture soil samples in the hollow portion of the drill for retrieving to the surface. One advantage of this approach is that you have actual soil samples you are working with. In the case of identifying the presence, location and depth of specific types of contaminants, this can be useful. Cone Penetration Testing Though geo-technical boring seems like a sufficient option for site subsurface investigation, geo-technical boring doesn’t provide the accuracy and efficiency that Cone Penetration Testing (CPT) can offer. Geo-technical Boring has the advantage that it uses many of the skills of conventional well drilling. Because the Boring operations and technical analysis, such as laboratory tests, are separate, Geo-technical Boring can require less skilled operators [...]

The Importance of Proper Soil Quality

Sometimes it's hard to imagine how important designing the proper foundation support for a structure can be. The public may assume that the ground we are standing on is pretty much stable and should be able to hold whatever we build on it, without consideration of soil quality. However, there are examples throughout history of structures that were built upon soil conditions that were not suitable for their weight. Perhaps the most famous is the Leaning Tower of Pisa. With better soil quality, it may have been known today as the Tower of Pisa Unfortunately for the constructors, the Tower was built upon a patch of soil that was too soft on one side for the pressure the structure would exert as it's height climbed. The Tower actually had begun leaning during the construction process and had quite a tilt before it was even completed. Over time, builders began to realize that in order to build magnificent structures, and to have them endure over time, they had to understand the geology they were building on. They had to be able to translate an understanding of the soil quality that is not able to be seen into foundation designs that would support even the tallest skyscrapers we build today. Through lots of experimentation, science, engineering and creative solutions, we've been able to evolve our understanding of how to perform a variety of soil tests and how to link that to solid design and construction methods that will support structures as varied as highway bridges and high-rise buildings. As you explore the resources that we've provided in our CPT University, you'll learn about a variety of soil tests and the advantages of each. Tests such as Standard Penetration Tests (SPT), Cone Penetration Tests (CPT) and other forms of testing all have their [...]

Why Are There So Many Kinds of CPT Rigs?

As you look through our website, you'll see that there are a number of different types of CPT Rigs. As you can imagine, they each have their purpose, or 'application'. In order to understand why different types of CPT Rigs exist, it's helpful to remember how CPT works in the first place. The goal of Cone Penetration Testing is to drive a hardened cone vertically into the the ground and to keep it moving at a specific rate of progress. The force that it takes to maintain the cone moving downward at a defined rate is an indicator of how hard the soil is at a given depth. The friction the cone sleeve encounters along the way gives us an indication of the make up of the soil. As you can imagine, as the cone progresses further downward and encounters different types of soils, sands, clays and rocks it can take a substantial amount of pressure to keep it moving! One of the first factors that influences the design of CPT Rigs is the maximum amount of pressure that will be required to perform a specific test, to a specific depth in a given geological area. As much as 20 tons of downward force may be required to perform a broad enough range of tests to make a given rig viable for a market. For every ton of downward pressure on the test cone through the rod system, you have to have a reaction force equal to this to keep the Rig from lifting up. This means that either the Rig has to be heavier than the maximum push force, plus a safety margin, or it needs to be anchored down in some way as to reliably resist the upward force generated by the test (or 'sounding'). Depending upon the [...]

Using a Compaction Test to Determine Site Safety Standards

Compaction is an engineering term used to describe the ability of a soil type to be treated with mechanical energy and compressed such that air voids are removed. With individual grains compressed to remove air voids, it becomes more difficult for the soil being compressed to 'settle' further on its own. The strength of the soil in loads other than compression can be increased because the individual particles within the soil become interlocked and friction can become a more important function of the soil behavior. Compacted soil, because air spaces between the particles are reduced has lower hydraulic conductivity (passes water less easily under a given pressure). Why do a Compaction Test? Compaction can be important when high loads such as building foundations may cause a soil to settle over time causing shifting or even collapse. It can be valuable for soil that you want to retain in place, such as along an embankment or behind a retaining wall to be compacted. The compaction process, by increasing the friction in the compacted soil helps to maintain against horizontal slippage which can either result in a landslide off from an embankment or in higher pressure behind a retaining wall, causing it to bow outwards. Because compaction lowers hydraulic conductivity, it can be useful, or even essential in the functioning of earthen dams, drainage ditches and levees. A measurement of compaction is the change in density, or weight per unit volume increase after the soil in question is compacted. That's why sometimes 'compaction' is also called 'densification'. This is actually not a correct designation as 'densification' actually includes both 'compaction' which is described above as well as 'consolidation'. Consolidation involves fluid flow out of the soil being densified, such as when you are treating clay heavy soils. Water is squeezed out from [...]

A Short Introduction into CPT and the ASTM Standards

If you have been thinking about expanding into the Cone Penetration Testing business but still need some more information to feel confident with your decision; or need further details to bring to your employer, you have come to the right place. This post is an introduction to the basics of CPT and how it correlates with the ASTM Standards to meet your needs and better serve your business. If this is the first time you have really considered entering the CPT business; CPT is the use of a hardened cone shape that is pushed into the ground to substantial depths for the process of collecting immediate onsite data. CPT has proven to be an inexpensive option that not only is safe and efficient but delivers accurate data at a faster rate. Not only is CPT an effective and inexpensive option for your drilling assignments, but it also meets the ASTM Standards, ensuring that it meets the standard of excellence (safe, quality, etc). CPT Data & ASTM Standards "ASTM International, formerly known as the American Society for Testing and Materials (ASTM), is a globally recognized leader in the development and delivery of international voluntary consensus standards. Today, some 12,000 ASTM standards are used around the world to improve product quality, enhance safety, facilitate market access and trade, and build consumer confidence" [ASTM]. To take a deeper dive into the value of ASTM Standards, take a look at this video: [/fusion_youtube]

Soil Quality in Geological Engineering

Agronomists, Civil Engineers, Geological Engineers and more will often talk about 'Soil Quality'. As a result, there can be varying definitions of what 'quality' soil means. That means that there are a wide variety of tests to determine 'Soil Quality'. What Does Soil Quality Mean for You? For the Agronomist, Soil Quality refers to the capacity of soil to provide a kind of function related to growing capacity. This will take into account the soils ability to support life as in its chemical properties (does it have enough nitrogen etc.), it's biological properties (does it have the right bio-system to support the production of certain types of crops), will it retain the right amounts of water, is it's grain size suitable for tilling etc. There are many tests that will help one to evaluate the agricultural viability of soils. For the Civil and Geological Engineer some of these tests might be valuable. For instance, in making recommendations in how to reclaim a 'brown field' (a site that was formerly industrial that is now being re-developed for other purposes) it can be useful to identify the level of ability of an area to support specific types of grasses. When performing earthworks, it is not uncommon to use plantings such as trees as part of the anchor system to help to hold berms and such in place. Knowing Soil Quality in this respect can help to support a good decision with respect to the structural support that a living ecosystem can bring. Generally though, Engineering types are after more specific physical properties in order to 'do the math' on how an engineered system will interact with the soil conditions that are present. This enables engineers to either recommend changing the systems in place (such as by excavating large quantities of soil out, [...]

New Geotechnical Exploration Firm in Southeast US: PalmettoINSITU

Vertek S4 Push System In Action Extracting underground data to determine soil parameters in order to efficiently provide foundation requirements Vertek customer Michael Cox has launched PalmettoINSITU, LLC, a geotechnical exploration firm specializing in extracting and presenting more exact data from coastal, southeastern, and southwestern soils prior to development and construction projects. Geotechnical engineers will contract with PalmettoINSITU to extract underground data to determine soil parameters in order to efficiently provide foundation requirements for: Bridges, multi-story buildings, private residences, nuclear power plants, wind turbines, cellular communication towers, municipal water tanks, water treatment facilities, sinkholes, profiling top-of-rock, directional boring, and many other critical applications prior to development and construction. About Michael Cox: Michael Cox spent 13 years with S&ME, a global Top-100 engineering firm before launching PalmettoINSITU in June of 2014. Michael Cox graduated from Florida Institute of Technology with an MS in Information Technology and a BS in Computer Information Systems. Cox also earned an AS in Civil Engineering Technology, including AutoCAD and Surveying certificates from Trident Technical College in Charleston. Michael Cox is known as the "Indiana Jones" of capturing soil data in the geotechnical engineering space, due to his reputation and innovation for getting in and out of some of the most challenging site locations. Before beautiful residences, commercial buildings, or major facilities are built, their raw land is typically rough, wooded, wet, or otherwise a challenge to physically enter in order to begin testing the soil. Vertek's S4 Push System offers maximum flexibility to access these site locations due to application on a variety of equipment. Michael Cox earned over a decade of geotechnical experience working on the following projects: Norfolk Naval Shipyard (Virginia), Andrews Air Force Base (Maryland), The Boeing Facility (South Carolina), The Bellefonte Nuclear Station (Alabama), Robinson Nuclear Power Plant (South Carolina), The Google [...]

Incotec Q&A: Cone Testing in Bolivia

CPT in South America Vertek's S4 Push System has made entry into the CPT market accessible for a growing list of geotechnical professionals. Here on our CPT U blog we often provide a closer look at some of these organizations and how their regional markets operate. One such company is a Bolivian construction and engineering group that's been in operation since 1968, but has just recently added CPT to their offerings thanks to a Vertek S4. Read on for our Q&A with Mario A. Teceros of Incotec. Provide a brief background on your company. How/when did it originate? It was established in 1968. Is one of the oldest operating construction companies in Bolivia. It was initially created to build urban infrastructure and housing. Rapidly entered to the civil works and the deep foundations market. Incotec also started with the first geotechnical equipment (SPT and DPM) in 1968. Since then, beside the experience in different type of projects (ranging from concrete structures to industrial constructions and dams), the speciality in deep and special foundations has been the main "stamp" of Incotec. Is family company and now the third generation is working. What is the scope and focus of Incotec today? More specialization in all the fields of its activities, mainly with the incorporation of cutting edge equipments for soil tests (SCPTu from Vertek), deep foundation construction (BG18, BG20 and BG 30 from Bauer, with tools for Full Displacement Piles, Cutter Soil Mixing, cased piles) and quality controls (From Pile Dynamics, PIT, Cross Hole and PDA). But the main product developed by Incotec during the last decade is the EXpander Body, a steel folded "balloon" that is installed at the tip of a pile or an anchor. The EB is then injected with grout to expand it, compacting the surrounding soil and [...]

Geotechnical Investigation and CPT Papers Now Available From CPT ’14

Did you attend CPT '14 in Las Vegas, Nevada? If so then you know the wealth of geotechnical expertise that was shared, and if not, then be sure to examine the scope of professional papers published from the event available for review now on their website. FEATURED PAPERS Whether you are a seasoned CPT veteran or just considering entering the cone penetration profession, the topics covered at CPT '14 provide current geotechnical expertise that you can benefit from. Some of the topics covered include: The effect of sleeve diameter on fs measurements Axial and torsional axisymmetric laboratory interface shear tests for CPT attachment studies Geotechnical Offshore Seabed Tool (GOST): A new cone penetrometer Evaluating rolling dynamic compaction of fill using CPT Verification of compaction grouting program using CPT in liquefiable soils Use of CPT for stability and performance evaluation of Mississippi River Revetment slope in New Orleans Role of CPTu in design of large Atlantic port terminal in Costa Rica Use of CPT for design, monitoring, and performance verification of compaction projects Using piezocone to assess strength gain of gold tailings in semi-arid environment Interpretation of geotechnical parameters from seismic piezocone tests Novel applications of CPT for verification of ground improvement projects Fault study using CPT, drill and trenching data Shear strength evaluation of preloaded stabilized dredged sediments using CPT