title: Investigation of degree of saturation in landfill liners using electrical resistivity imaging.
abstract: During construction of compacted clay liners and evapotranspiration (ET) covers, quality control involves laboratory and field tests in individual lifts. However, the available methods may be inadequate to determine non-uniform compaction conditions, poor bonding of lifts, and/or variable soil composition. Moreover, the applicability of the available methods is restricted, in many instances, when spatial variability of the subsurface is expected. Resistivity Imaging (RI) is a geophysical method employed to investigate a large area in a rapid and non-destructive way. High resistivity of clay liner soil is an indication of a low degree of saturation, high air-filled voids, and poor lift bonding. To utilize RI as a quality control tool in a landfill liner, it is important to determine the saturation condition of the compacted soils because compaction and permeability of liner soil are functions of degrees of saturation. The objective of the present study is to evaluate the degree of saturation of a municipal solid waste (MSW) landfill liner, using RI. Electrical resistivity tests were performed in the laboratory, at varied moisture contents and dry unit weights, on four types of soil samples, i.e., highly plastic clay (CH), low plastic clay (CL), Ca-bentonite, and kaolinite. According to the experimental results, electrical resistivity of the specimens decreased as much as 15.3 times of initial value with increase in the degrees of saturation from 23% to 100%. In addition, cation exchange capacity (CEC) substantially affected resistivity. A multiple linear regression (MLR) model was developed to correlate electrical resistivity with degree of saturation and CEC using experimental results. Additionally, RI tests were conducted on compacted clay liners to determine the degrees of saturation, and predicted degrees of saturation were compared with the in-situ density tests. The study results indicated that the developed model can be utilized for liner soils having CEC, resistivity and degrees of saturation between 13.3 and 79cmol+/kg, and 2.6 and 504.3Ohmm, and 21.8% to 100%; respectively.
authors.affiliation: Drash Consultants, 1045 Central Parkway North, Suite 103, San Antonio, TX 78216, United States. Electronic address: golam.kibria@mavs.uta.edu.
authors.forename: Golam
authors.initials: G
authors.lastname: Kibria
authors.affiliation: Department of Civil Engineering, University of Texas at Arlington, 417 Yates St, NH 404, Arlington, TX 76019, United States. Electronic address: hossain@uta.edu.
authors.forename: Md Sahadat
authors.initials: MS
authors.lastname: Hossain
mesh_terms: D002412:Cations / Q000737:chemistry; D007474:Ion Exchange; D008962:Models, Theoretical; D012037:Refuse Disposal / Q000379:methods*; D012989:Soil Pollutants / Q000032:analysis*; D062611:Solid Waste / Q000032:analysis*; D064091:Waste Disposal Facilities
chemical_list: D002412:Cations; D012989:Soil Pollutants; D062611:Solid Waste
keywords: Clay liner; Degree of saturation; Final cover; Quality control; Resistivity imaging; Statistical model