Oceana Gold Project Quattro Project Quattro Geochemical Assessment – Tailings and Overburden, Treatment and Mitigation \\na.aecomnet.com\lfs\APAC\Christchurch-NZCHC1\Legacy\Projects\605X\60544823\6. Draft Docs\6.1 Reports\Waihi North\App D - Kinetic and Column Testing\WNP Draft v6_App D (Kinetic Column Testing)_20220504.docx Revision 5 – 07-Aug-2020 Prepared for – Anderson Lloyd – Co No.: 5719274 D3 Column Testing D3.1 Methodology Initially, six column tests were undertaken on-site to support and supplement the findings of the kinetic testing to characterise likely trace element loadings and treatment options, and to define a methodology for backfill placement. Three of these columns were subsequently disbanded and replaced with three additional columns. The standard operating procedure for the columns set up and operation is provided in Attachment A. This document refers to Gladstone and Favona rock. The Favona rock is from similar depths to the GOP hydrothermal breccia and andesite materials, so overlying the Favona underground, and is located in an area immediately north of the GOP. The rock sample from outside the GOP void are referred to as “adjacent to GOP” to differentiate between samples that are from within the GOP void and those to the north of the void. Approximately 60 kgs of overburden was required for each of the nine columns. At the time of selection, samples were selected on the basis of the availability of material, with the volumetric ratios of Andesite and Hydrothermal Breccia encountered in the pit maintained and tested in the columns. These ratios have since been amended within the final pit profile, therefore the ratio of Andesite:Breccia within the columns differ than expected in the balance of overburden material from the Gladstone pit. However, the observed differences are considered insignificant. Refer to Table D8 for a summary of the column setup. Table D8 Ratio of Andesite to Breccia Material in Column Set Up Column Name Treatment Method Treatment Week Ratio of PAF Andesite Material Ratio of PAF Breccia Material Gladstone Pit Balance Inclusive of all Overburden Material 38% 13% Relative Gladstone Pit Balance Only Andesite / Breccia Material 75% 25% Col 1 - - 79% 21% Col 2 Saturated Week 11 79% 21% Col 3 Limestone Dosed Week 11 79% 21% Col 4 - 69% 31% Col 5 Saturated Week 11 69% 31% Col 6 Limestone Dosed Week 11 69% 31% Col 7 Compacted Week 0 82% 18% Col 8 Layered Week 0 82% 18% Col 9 Limestone Blended Week 0 63% 37% Col 10 Control - - - The following criteria were used to guide selection: • Core intervals were selected from cores spatially distributed across the projected pit volume where possible; • In order for there to be sufficient volume of material, core intervals from a wider area (i.e. outside of the projected pit) have been utilised. Where this has occurred, care has been taken to select material that is considered similar in nature (geologically and geochemically) to overburden material expected from the Gladstone pit. • Core intervals with ore-grade concentrations of Au (where existing data was available) and veins or highly silicified zones were excluded;
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