Supporting Technical Assessments

Oceana Gold New Zeland Limited Hydrogeology Support for WKP Underground Updated Conceptual Model 2.2. Review of Golder field notes and data indicate that it was not possible to measure downhole water levels in most of the angled boreholes prior to starting packer tests. Static water levels were estimated from available data using the following assumptions: For each packer test, the data-logging pressure transducer (datalogger) is inserted into the test interval. Once packers are inflated, the test interval is hydraulically connected to the surrounding fractured rock aquifer. The initial pressure head on the datalogger (prior to water injection) reflects the water column in the surrounding aquifer system. These assumptions may not be met in all cases, and water levels calculated using these assumptions are therefore considered approximate. To estimate static water levels, FloSolutions converted downhole depth of the test interval / datalogger in the angled borehole to elevation above MSL (mean sea level) and added the measured datalogger pressure to obtain the water table elevation. Specific steps taken to estimate water levels from packer test data and import them into leapfrog were: Compilation of drillholes: coordinates, azimuth, dip and depth of the hole. Compilation of tests intervals (from / to). Import information in Leapfrog to get the projected coordinates of each interval. Analysis of each packer test data (DataCan Information Sheet) to get the depth of the logger and meters of water above the logger. Conversion of units to projected elevations using the dip of the hole. Generation of a CSV file with projected coordinates and projected WL for import in Leapfrog. Generation of a 3D surface in Leapfrog using the water level data from packer tests. Borehole data used for water level calculations is summarized in Table 2-1. Table 2-1 Drill collars and survey data for tests holes, VWPs, and standpipe piezometers Hole ID Collar Az Dip1 Depth Type E N Z

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