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 (SA) was quantified from the soil water characteristic curves (SWCC) which were developed based on laboratory experiments and field instrumentation data. Required SWS (SR) was also measured from the field monitoring results. Based on analysis, the relative storage ratio (SR/SA) was observed to be greater than unity (1) in most of the cases, indicating potential percolation. The SR/SA 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.

Highlights

  • Water balance cover, known as evapotranspiration (ET) cover, is an emerging method for landfill closure

  • To address the effect of change in the unsaturated hydraulic properties of the soil on the percolation rate, this paper evaluates the directly measured percolation from six constructed lysimeters and compares with estimated percolation from soil water characteristic curves (SWCC) parameters

  • The study was conducted at the City of Denton municipal solid waste (MSW) landfill, Denton, Texas, which is geographically located in the semi-humid region

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Summary

Introduction

Known as evapotranspiration (ET) cover, is an emerging method for landfill closure. Many field demonstrations of ET cover have been evaluated through lysimetry method It is reported from different research that large lysimeters (> 100 m2) provide greater sensitivity. Field measured unsaturated soil parameter may potentially provide a better resolution to predict the rate of percolation for water balance covers [14]. To address the effect of change in the unsaturated hydraulic properties of the soil on the percolation rate, this paper evaluates the directly measured percolation from six constructed lysimeters and compares with estimated percolation from SWCC parameters. Both laboratory generated and field constructed SWCCs were considered in the analysis. The thickness of the cover storage layer was evaluated from the field investigated water balance data

Materials and Method
Test Section and Instrumentation
Sensor Installation
Physical and Hydraulic Soil Properties
Vegetation
Soil Properties
Measurement of SA from Field SWCC
Results and Discussion
Computation of Percolation
Evaluation of Storage Layer Thickness
Conclusion
Full Text
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