Leachate leakage investigation, assessment and engineering countermeasures for tunneling underneath a MSW landfill

• Published in: Engineering geology Vol. 265
• Main Authors: Feng, Shi-Jin, Zhao, Yong, Zhang, Xiao-Lei, Bai, Zhen-Bai
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.02.2020
• Subjects: Electrical resistivity tomography; Geological drilling; Leachate leakage evaluation; Mountain tunnel; Municipal solid waste landfill; Transient electromagnetic method; Geological drilling; Electrical resistivity tomography; Leachate leakage evaluation; Mountain tunnel; Municipal solid waste landfill; Transient electromagnetic method
• ISSN: 0013-7952; 1872-6917
• DOI: 10.1016/j.enggeo.2019.105447

The Jigongshan mountain tunnel (Shenzhen, China) was designed to cross underneath the Xiaping Municipal Solid Waste (MSW) Landfill with the shortest vertical distance of 36 m. To take suitable measures to make the tunnel leachate-proof, the geological conditions and the leachate distribution in and under the landfill were detected and evaluated in this study. Firstly, geological and geophysical methods, including electrical resistivity tomography (ERT), transient electromagnetic method (TEM), and geological drilling and sample analysis, were employed on the ground and in the underground to perform a multi-pronged investigation. Meanwhile, the leakage levels were established to evaluate the extent of the leakage as well as its effects on the tunnel. Furthermore, the corresponding measures to achieve a leachate-proof tunnel were also provided. The test results indicated that the leachate was well confined by the liner system in the landfill. Although fracture zones containing water were detected under the landfill, which may preferentially act as pathways for the leachate flow, no pollution index of the underground water exceeded the allowable value, and no leachate leakage had occurred yet. Eventually, an integrated strategy comprised of a multi-pronged investigation, leakage assessment, and engineering countermeasures was developed to ensure the safety of the tunnel construction and operation. This study offers a valuable reference for similar investigative projects concerning underground construction near MSW landfills worldwide. •The relationship between degree of weathering rock and electrical resistivity was obtained.•Landfill and subsurface properties were identified by both ground and underground investigations.•Integrated investigation strategy for tunnel construction under MSW landfills was established.•Leachate-proofing and treatment measures based on leakage levels were provided.