Mapping fly-ash water pond leakage with TEM and IP data at Loy Yang coal-mine (Australia)
A. Viezzoli, J.P. Cull and D. Massie
Journal name: Near Surface Geophysics
Issue: Vol 4, No 5, October 2006 pp. 305 - 311
Info: Article, PDF ( 1.74Mb )
Price: € 30
The fly-ash water pond at the Loy Yang power station (Latrobe Valley, Victoria, Australia) seeps and therefore presents a hazard to the local environment from its high total dissolved solids content. A transient electromagnetic survey (TEM) was completed to investigate the contaminant plume in more detail. The contaminate plume was successfully delineated; however, multiple contiguous soundings featured late-time negative decays not typically recorded in coincident-loop TEM surveys. This indicates that conductivity is frequency-dependent. These anomalous soundings suggested the presence of a shallower contaminate plume than that mapped by the boreholes and therefore further analysis was required. An induced polarization survey revealed that the area where the late-time negative responses were recorded coincided with a shallow conductive and extremely chargeable anomaly. A simple power-law relationship holds between the negative transients decay rates and normalized apparent chargeability. Analysis on soil samples obtained from auger holes related the polarization anomaly to clay-, organic- and metal-rich layers of fill material.