Coal Age Magazine - For more than 100 years, Coal Age has been the magazine that readers can trust for guidance and insight on this important industry.
Issue link: https://coal.epubxp.com/i/706026
July 2016 www.coalage.com 25 coal ash continued tially across all 11 TVA plants, with 7,000 sensors in the field sending data to a GIS database every five minutes. While initially created outside of the TVA due to IT space, the system is now owned and operated by the utility. It is an ongoing process to keep it at peak perfor- mance, and the group is continually build- ing upon it. "We're in operational mode," Hill, TVA's environmental scientist, said. "We're always looking at the instruments, procedures with them [plants]…[and] calibrations." The network is flexible, so as instru- ments are added and removed from TVA's plants, the system can easily incorporate new and abandon old segments. As part of this effort to go high-tech with an old problem, the TVA has also com- mitted itself to moving from wet impound- ments to dry storage, something it moved toward even before today's fast-chang- ing federal regulations were introduced. Its goal is to have all wet impoundments closed in four to six years in favor of dry storage. With that change, the risk of an- other Kingston-type breach is eliminated. "That's where the birth of intelligent compaction has come from," said Walker. "We wanted to make sure material would never go anywhere once [placed]." That portion of the project began in 2011, when the TVA joined together with Iowa State University to research how to calibrate the ash storage area's technology for the easiest monitoring. What once de- pended on individuals to perform in the field and analyze manually (and remotely by sending information to the university, then await a response) TVA can now view via a dashboard with all collected data in one place, the ability to view anomalies in the now ultra-compacted ash pile quickly, and even a camera feed of the compaction roller at work. Verification of stability can then be achieved by auditing the data, including density, strength, voids and other factors us- ing in-ground vibratory equipment; in short, when things don't add up, the utility knows that something is amiss with the specific landfill being examined. A system of num- bers and associated colors on the monitors also aids in discovering potential problems and staying ahead of issues. The label "cut- ting-edge" certainly applies, considering that all previous technology and methods simply did not have these capabilities. The intelligent compaction systems are currently deployed at two TVA sites, and a third is expected to be mobilized lat- er this year. The TVA is aiming to have six landfills outfitted with the system by 2023 or 2024, though that figure could change if the number of plants in its portfolio change in that time span. "From the very beginning, it was al- ways about safety, of people and environ- ment. [It will also] improve costs to the ratepayer and provide efficiency in the field," McClung said. "We're making sure we're reducing environmental impacts, any impacts, for TVA. In the long run, what we want to do is automate things, reducing the amount of people that need to go get the info. Making it real time — we can then make changes more efficiently." The top goal, the group stressed, was indeed safety and to be good stewards to the public and regional communities. Looking ahead, that goal will not change, and they noted that the TVA is "light years" ahead of the industry in terms of managing ash placement; its role for the future, then, is continuing to make the en- tire system smarter and better. "Most of these landfills are going to have to be managed 30 to 50 years; [this] management tool will help us place this in smallest space possible. We will get smart- er in terms of understanding ash itself [and] will be learning much more about ash and how it forms," McClung said, add- Students and researchers at North Carolina A&T; State University's Center for Composite Materials Research recently announced a breakthrough in its work, a new technique to store coal ash underground safely and also to recycle the ash byproduct into lightweight building materials. At the heart of the group's work is mixing the coal ash with polyurethane to create a substance that can then be pressed together for home siding, decking material and mold- ings. For long-term storage, the school said that pressing into blocks; in addition to tak- ing less room at a fill site, it could also be at the ready for recycling uses down the line. "This coal ash is not waste," said Kuni- gal Shivakumar, director of the center, in a June interview with the Greensboro News and Record. "It is a valuable resource if we handle it properly. ... We have a problem, and yes, we have a method of solving the problem." Local chemist Wade Brown holds the patents for parts of the polyurethane pro- cess. He noted to the paper that while the coal ash provides bulk for the material, it is chemically inactive while a part of that mixture, because the urethane component is doing the work. NC A&T;'s work came from a two-year, $400,000 grant from the state of North Car- olina to examine the potential of coal ash for "beneficial reuse." It also follows work the school had already completed on a nautical coal ash product, Eco-core, which uses only a specific type of ash. The Future of Ash, According to North Carolina A&T; Proper, effective compaction has helped the utility reduce its environmental footprint while also making its Proper, effective compaction has helped the utility reduce its environmental footprint while also making its sites safer.