Eighth International Conference on Case Histories in Geotechnical Engineering
Monitoring Seasonal Variation of Soil Hydraulic Conductivity of Evapotranspiration (ET) Cover
Publication: Geo-Congress 2019: Geoenvironmental Engineering and Sustainability (GSP 312)
ABSTRACT
One of the main purposes of landfill cover system is to prevent the water infiltration into the waste mass and eventually minimize the generation of leachate. In this effort, the most prevalent parameter to control is the percolation of rainfall through the cover system into the waste mass. In addition to this, if the cover system utilizes an evapotranspiration (ET) or water balance cover, understanding the hydraulic behavior of soil becomes especially important. Environmental loading conditions can change drastically throughout the seasons, which in turn can substantially alter the hydraulic conductivity of the cover soil, and hence, affect the performance of the ET cover system. Therefore, assessment of seasonal variation of soil hydraulic conductivity is vital. To address this, a study was conducted on an existing ET cover in the city of Irving landfill. The objective of the study was to monitor the change in the saturated hydraulic conductivity of the ET cover soil at variable environmental conditions. Due to its versatility, the Guelph permeameter was used to estimate the in situ saturated hydraulic conductivity of the ET cover soil. However, the more commonly used Boutwell permeameter (two-stage borehole test) was also used to compare the two methods. To develop a better understanding, the selected sites were monitored monthly at depths of: 15.24 cm (6″), 30.48 cm (12″), and 60.96 cm (24″). Based on the field investigation, it was observed that the average saturated hydraulic conductivity decreased proportionally to an increase in the investigated depth. The registered saturated hydraulic conductivity value during fall (October 2016) at 15.24 cm (6″) depth (2.38×10-5 cm/sec) was almost 100 times higher than the 60.96 cm (24″) depth (4.68×10-7 cm/sec). Furthermore, it was observed that the saturated hydraulic conductivity of the cover soil at all of the investigated depths, varied in a cyclical pattern in accordance to the changing seasons. The highest values were logged during the summer seasons, whereas, the lowest values were observed in the winter season. Saturated hydraulic conductivity values measured at different times of the year varied as much as 100 times at corresponding depths.
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Information & Authors
Information
Published In
Geo-Congress 2019: Geoenvironmental Engineering and Sustainability (GSP 312)
Pages: 72 - 81
Editors: Christopher L. Meehan, Ph.D., University of Delaware, Sanjeev Kumar, Ph.D., Southern Illinois University Carbondale, Miguel A. Pando, Ph.D., University of North Carolina Charlotte, and Joseph T. Coe, Ph.D., Temple University
ISBN (Online): 978-0-7844-8214-8
Copyright
© 2019 American Society of Civil Engineers.
History
Published online: Mar 21, 2019
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