November 11, 2021

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Girish Kumar Coauthored a Paper on a New Model for Effects of Leachate Recirculation System Variables on Bioreactor Landfill Performance in the International Journal of Geomechanics

Girish Kumar, Ph.D. (California) coauthored a paper entitled "Effects of leachate recirculation system variables on long-term bioreactor landfill performance using coupled thermo-hydro-bio-mechanical model" that was published in the International Journal of Geomechanics in Volume 21, Issue 5 May 2021.

Girish was the lead author, and his coauthor was Krishna R. Reddy.

Girish Kumar is a Senior Staff Professional based in California with a focus on site assessment and remediation consulting. He has academic and research experience in geotechnical and geoenvironmental engineering, including landfill design and analysis; environmental remediation; numerical modeling and analysis of geosystems; and life cycle assessment and sustainability quantification. Girish has published over 40 research articles and his work has been recognized by several professional organizations including the American Society of Civil Engineers (ASCE), Environmental Research and Education Foundation (EREF), Solid Waste Association of North America (SWANA), and Air & Waste Management Association (A&WMA).

The International Journal of Geomechanics (IJOG) focuses on geomechanics with emphasis on theoretical aspects, including computational and analytical methods and related validations. Applications of interdisciplinary topics such as geotechnical and geoenvironmental engineering, mining and geological engineering, rock and blasting engineering, underground structures, infrastructure and pavement engineering, petroleum engineering, engineering geophysics, offshore and marine geotechnology, geothermal energy, lunar and planetary engineering, and ice mechanics fall within the scope of the journal. Specific topics covered include numerical and analytical methods; constitutive modeling including elasticity, plasticity, creep, localization, fracture and instabilities; neural networks, expert systems, optimization and reliability; statics and dynamics of interacting structures and foundations; liquid and gas flow through geologic media, contaminant transport and groundwater problems; borehole stability, geohazards such as earthquakes, landslides and subsidence; soil/rock improvement; and the development of model validations using laboratory and field measurements.


This study will apply a newly developed coupled thermo-hydro-bio-mechanical (CTHBM) numerical model to a typical full-scale landfill cell geometry with horizontal trenches (HTs) as the leachate recirculation system (LRS) and will evaluate the effect of the leachate injection pressure (IP), the horizontal spacing of the leachate injection locations (IS), and the mode of leachate injection (IM), on some of the major long-term hydraulic (e.g., wetted area), mechanical (e.g., differential waste settlement), biochemical [e.g., methane (CH4) gas production], and thermal (e.g., elevated temperatures) characteristics of bioreactor landfills. Based on the results from a series of numerical simulations with different IP, IS, and IM, it was determined that the variable IP had the most significant impact on the landfill performance compared with IS or IM. Higher IPs lead to a linear increase in the wetted area and a corresponding increase in the degraded waste area, thereby reducing the time taken for waste stabilization. However, an increase in IP leads to larger elevated temperature zones within the landfill and larger differential settlements on the landfill surface. Larger IS caused significantly higher differential waste settlements due to the formation of unwetted zones within the landfill cell. Increasing the duration of gaps between the intermittent injection periods significantly reduced the extent of elevated temperature zones formed within the landfill. The relative shear displacements in the geosynthetic interface in the bottom liner and final cover system were mainly influenced by the IP.

More Information

Learn more about the article: Effects of Leachate Recirculation System Variables on Long-Term Bioreactor Landfill Performance Using Coupled Thermo-Hydro-Bio-mechanical Model | International Journal of Geomechanics
Learn more about the International Journal of Geomechanics: International Journal of Geomechanics | ASCE Library
For consultation regarding the geotechnical and geoenvironmental practice, contact Girish Kumar at This email address is being protected from spambots. You need JavaScript enabled to view it.
Learn more about Girish at: Girish Kumar | LinkedIn