Estimation of percolation of water balance cover using field scale unsaturated soil parameter

¹ Prairie View A&M University, Civil Engineering Department, 100 University Drive, Prairie View, TX 77446, USA
² SUNY Polytechnic Institute, College of Engineering, 100 Seymour Road, Utica, NY 13502, USA
³ University of Texas at Arlington, Civil Engineering Department, 416 Yates Street, Arlington, TX 76019, USA
⁴ SCS Engineers, Department of Solid Waste Service, 12651 Briar Forest Drive, Houston, TX 77077, USA

^* Corresponding author: mdalam@pvamu.edu

Abstract

Water balance covers for landfill closure are used as a barrier which act with the natural processes to reduce percolation. The ideal performance of water balance cover is characterized by the minimal quantity of percolation. The rate of percolation of water balance cover largely depends on unsaturated soil behavior. In this study, percolation was evaluated through unsaturated soil parameters of six instrumented lysimeters. The field instrumentation included moisture sensors, tensiometers, rain gauge, dosing siphon, and pressure transducer. Soil water storage (SWS) capacity (S_A) was quantified from the soil water characteristic curves (SWCC) which were developed based on laboratory experiments and field instrumentation data. Required SWS (S_R) was also measured from the field monitoring results. Based on analysis, the relative storage ratio (S_R/S_A) was observed to be greater than unity (1) in most of the cases, indicating potential percolation. The S_R/S_A was also found competent to identify the lysimeter with higher quantity of percolations. The estimated percolation from the laboratory experimented and field generated SWCCs fairly resembled with the actual field measured percolation. The analyzed results also developed a framework to estimate the thickness of the cover storage layer required to manage percolation for the specific region of the study area.