Broadbent, M. 1992 Leachate detection using electrical resistivity measurements at a refuse disposal landfill near Kaiapoi. Lower Hutt: Institute of Geological & Nuclear Sciences. Institute of Geological & Nuclear Sciences science report 92/13. 36 p.
Abstract: Schlumberger resistivity soundings and Wenner resistivity traverses have been made in the vicinity of the long used Kaiapoi refuse disposal landfill and tip. The near flat area around the tip is underlain by about 10 to 12 m of sands and grits overlying thin fine lagoonal deposits, which themselves overlie predominantly coarser sediments. The water table is mostly at a depth of between 1 and 2 m, and the average horizontal hydraulic gradient in the surface sediments is very low. An area of anomalously low resistivity has been defined which is probably associated with a leachate plume from the tip. Specimens of leachate were recovered from the area where resistivities were anomalously low. The resistivity measurements suggest the leachate is spreading preferentially in a direction about 100 east of south. The physical features of the investigated site make it suitable for comparative tests of galvanic resistivity, inductive resistivity, and radar measurements for detecting and defining leachate.