WKP PFS – Geotechnical Section Approved by: Approval Date: TBA OceanaGold PEX-000-PLN-046-A Page 5 of 22 1.4 Rock mass quality parameter The logged parameters Jn, Ja, Jr and rock quality designation (RQD) that were provided in the geotechnical database were used to calculate Barton’s Q’ value (Barton et al., 1974; NGI, 2015). Q’ = (RQD/Jn) x (Jr/Ja) (Equation 1) All geotechnical logging located within the current PFS mine design area was considered. Logging related to the area adjacent to the T-Stream vein was excluded because it is located too far away from the current PFS mine design zone. The data that was analysed involves a sample size population of 516 rows of logging data with the full suite of Q’ parameters. The total length of core that was evaluated was 1,910 metres. The logging intervals were based on geotechnical domains, therefore the interval lengths for each line of data is not equal. The data was analysed according to 1st quartile and 2nd quartile (median) values. The Q-ratings were converted to Geological Strength Index (GSI) values using the standard empirical conversion formula. The GSI ratings were converted to a weighted average that was based on the interval length, and then the final GSI weighted average was converted back to a Q’ value using the standard empirical conversion formula. GSI = 9*lne(Q’) + 44 (Equation 2) The table below shows a summary of the drill holes and zones used to evaluate the rock mass quality. The actual geotechnical logging database has Q’ drill hole intervals that are a subset of the zone lengths shown below. Because the current WKP mine design involves development and stoping on a series of sub-parallel veins, the data cannot be easily categorized as being “20m into the hanging wall” or “20m into the footwall.” However, the geotechnical logging intervals were categorized as being located in either the hanging wall, the footwall, or the vein. This was done by looking at each drill hole in the drill hole database model, and then looking at the relative location within the solids models of all the known veins. In the case of a drill hole traversing through subparallel veins, the description of “footwall” or “hanging wall” was based on the relative location to the nearest vein. Table 2: Summary of drill holes and zones used to evaluate the rock mass quality Drill hole From To Metres WKP50 45.0 110.8 65.8 WKP50 133.0 160.0 27.0 WKP50 170.9 171.7 0.8 WKP50 187.7 194.3 6.6 WKP50 195.0 347.0 152.0 WKP50 352.5 396.6 44.1 WKP52 396.9 433.5 36.6 WKP53 558.0 616.0 58.0 WKP54 429.8 558.0 128.2 WKP57 227.8 265.6 37.8 WKP57 269.2 303.2 34.0 WKP60 440.0 451.3 11.3 WKP63 373.1 375.6 2.5 WKP63 376.2 502.3 126.1 WKP64 238.9 241.5 2.6 WKP66 278.4 328.2 49.8 Drill hole From To Metres WKP71B 337.7 491.6 153.9 WKP74 85.3 91.3 6.0 WKP74 340.3 363.7 23.4 WKP74 365.0 370.9 5.9 WKP74 372.4 389.0 16.6 WKP77 373.8 392.0 18.2 WKP79 360.0 502.6 142.6 WKP80 207.0 265.2 58.2 WKP81 398.2 523.6 125.4 WKP83 373.0 446.0 73.0 WKP85 300.0 350.0 50.0 WKP86 336.0 439.4 103.4 WKP87 220.0 320.0 100.0 WKP89 211.0 257.1 46.1 WKP91 236.0 307.0 71.0 WKP93 300.0 433.4 133.4
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