Golder Associates New Zealand Limited were part of the geotechnical site investigation for a proposed tailings storage facility and raw water dam associated with the Phu Bia Mining Gold-Silver Project in Laos. The site geology is primarily a strong sandstone unit that exhibits `corestone` weathering, leading to a distribution of corestone boulders present within residual soil. The role of Golder Associates was to characterise the subsurface, with a view towards identifying any significant corestones. It will be necessary to ensure that foundation loads are supported by bedrock, rather than corestones.

Golder Associates had to characterise the subsurface with a view towards identifying any significant corestones. A range of Electrical Resistivity (ERI) arrays and acquisition setups were tested in order to determine the most effective and efficient approach to surveying at the site. Data collected in the field underwent preliminary processing each evening for QA/QC. This allowed for guidance of the following day`s activities.

ERI surveying was found to be effective at targeting a range of subsurface features, including clear structure, resistive laterite soils and buried corestones. Similar ERI results were observed across the survey site, implying consistent ground conditions. The results also displayed a high level of repeatability, implying that the data collected was of good quality and representative of ground conditions.