What question did this study set out to answer?

This study aims to map weak zones and leachate pathways beneath the Rumah landfill using shear-wave imaging.

May 26, 2026Open Access

Dense MASW shear-wave imaging of weak-zone networks and preferential leachate pathways beneath rumah landfill site, central saudi arabia

Key Points

This study aims to map weak zones and leachate pathways beneath the Rumah landfill using shear-wave imaging.
Acquired 26 MASW profiles with a 24-channel split-spread array using a 10 kg weight-drop source.
Processed data to image near-surface conditions to a depth of approximately 30 m.
Identified three geoseismic units based on shear-wave velocities (Vs) and interpreted localized low-Vs weak zones.
Detected low-Vs weak zones (< 0.76 km/s) mainly in the upper 2-12 m, indicating reduced shear stiffness.
Identified three geoseismic units with varying stiffness and thickness, affecting local hydraulic susceptibility.
Provided a framework for evaluating susceptibility to leachate migration and subsurface conditions.

Abstract

Landfills in arid regions may contribute to potential soil and groundwater concerns, as episodic rainfall, heterogeneous cover materials, and fractured carbonate bedrock may create preferential infiltration pathways. In central Saudi Arabia, landfill sites commonly overlie carbonate formations where weathering, fracturing, and dissolution can produce strong lateral variations in near-surface stiffness and hydraulic susceptibility. This study presents a dense MASW-based stiffness model to screen for shallow weak zones and fractured/weathered carbonate intervals beneath Rumah landfill site in central Saudi Arabia. We acquired 26 MASW profiles using a 24-channel split-spread array with 1 m receiver spacing and a 10 kg weight-drop source, and processed the data to image the near surface to an effective depth of approximately 30 m. The resulting 2D shear-wave velocity sections define three Vs-based geoseismic units: (1) a surficial cover/near-surface low-stiffness unit with Vs of approximately 0.35-0.76 km/s and thickness of about 2-8 m; (2) an intermediate fractured/weathered carbonate interval with Vs of approximately 0.76-1.50 km/s and typical thickness of about 5-15 m; and (3) a deeper competent carbonate/limestone domain with Vs > 1.50 km/s, locally approaching approximately 2.3 km/s. Localized low-Vs weak zones (< 0.76 km/s) are repeatedly detected, mainly within the upper 2-12 m and commonly 2-6 m thick. These anomalies are interpreted as zones of reduced shear stiffness that may reflect disturbed ground, elevated moisture, increased porosity, weathering, fracturing, or combinations of these factors. The results, therefore, provide a defensible MASW-based pathway-susceptibility screening framework and identify priority targets for confirmatory drilling, hydrochemical sampling, and fluid-sensitive geophysical methods such as ERT/IP. The findings should be interpreted as evidence of susceptibility and subsurface heterogeneity, not as direct proof of active leachate migration.

Ask AI

Helpful

Bookmark

View Full Paper