Field measurement of pore pressures and liquid-gas distribution using drilling and ERT in a high food waste content MSW landfill in Guangzhou, China

Abstract

Systematic field measurements were carried out at the sliding area of the Xingfeng Landfill, which is a large high food waste content municipal solid waste (HFWC-MSW) landfill. Sixteen boreholes were drilled and pore pressure transducers, gas pressure pipes and inclinometer pipes were installed to measure pore water pressures, pore gas pressures and waste displacements, respectively. Two measuring lines of electrical resistivity tomography (ERT) were arranged to analyze the liquid-gas distribution in the waste mass. In addition, a stability analysis was conducted on the basis of the measured results. The main findings are as follows: (i) In the regions at the depths of 5–15 m in the waste mass, the saturation level of the waste was relatively high, and high gas pressures were not evident. However, in the regions at depths blow 15–20 m, the waste was unsaturated, and there were obvious local high gas pressures, (ii) The low-water-content and high-water-content zones obtained by ERT corresponded to the low-saturation and high-saturation zones inferred by the measurements of the water and gas pressures, respectively, indicating the consistency between the results of ERT and drilling, and (iii) By field measurement and stability analysis, the correlation between high gas pressures and sliding was confirmed, indicating high gas pressures may be the critical cause for the frequent waste sliding. In addition, the possible causes for the liquid-gas distribution and high gas pressures in the waste mass were discussed by considering the biodegradation characteristics of HFWC-MSW. This study provides the references for field measurement and stability control in similar landfills.