Cone penetration testing (CPT) is an advanced site investigation method for assessing and recording the properties of sediments. The field test involves the use of a static hydraulic advancement system to slowly advance a probe equipped with multiple measurement sensors into the sediment directly below. The CPT system collects and records high resolution data to determine site characteristics such as density, shear strength, soil behavior type, and other derived properties. The data is then analyzed by engineers to understand what improvements need to be made to support the proposed load bearing structure.
A lesser-known application for CPT is the investigation of coal-fired power station by-product deposit sites, sometimes referred to as “coal ash ponds.” Keep reading to learn why CPT is a great method for investigating these sites.
How CPT Testing is Helpful
Coal ash can take many forms, including solid particles, liquid slurry, or gas. Coal ash is often disposed of in large ponds enclosed by earthen dams, which can be a potential hazard if the material is not homogenous, or the confining dam fails. As one might expect, coal waste sites are highly regulated by the U.S. Environmental Protection Agency (EPA) and require investigation to evaluate the overall site’s stability and failure risk. By understanding the composition and strength of coal ash and confining structures, geotechnical engineers can make informed decisions and predictions based on collected site data, such as how sediment may behave during an earthquake or severe weather event and what risk mitigation efforts should be implemented preventing catastrophic damage.
CPT site characterization allows engineers to measure high resolution sediment characteristics safely and efficiently with minimal disruption to subsurface material. Measuring sediment properties in-situ, or “in the original place,” is important as it gives engineers the most accurate assessment of what is deposited at specific depths. Other, more invasive testing methods may disrupt the soil enough that the collected samples are not an accurate reflection of the in-situ sediment conditions.
CPT is an effective and easy way to investigate subsurface conditions of coal ash deposits as shown above. However, not every CPT system is the right fit for coal ash and other waste sites.
Vertek’s S4 CPT Sounding System offers modularity and can be used with a wide track skid steer to provide low ground pressure footprint and lower capital investment. The benefit of the S4 is that it can used as needed on a site and be adapted to common construction equipment via quick attach or mounted to a custom self-sufficient trailer.
Vertek’s Track CPT Systems offer the ability to have a powerful track-mounted CPT system that also offers low ground pressure and built for high levels CPT production testing. With a lighter and distributed footprint, these track systems are ideal for navigating less stable ground.
As former CPT providers, Vertek builds systems that provide the reliability and ease of use we would want and demand from a system. With less than a day of training, we can have you up and running. Contact Team Vertek to discuss your needs and our solutions.