WKP PFS – Geotechnical Section Approved by: Approval Date: TBA OceanaGold PEX-000-PLN-046-A Page 11 of 22 1.5.6 Sonic Velocity Sonic velocity tests were done on Sample WKP2020RP-004 at the E-Precision laboratory. This sample was taken from WKP93 at a depth of 393.3 to 394m in the Eastern Rhyolite. The density of this sample was only 2.17 t/m3, and this is far below the median density of 2.5. The tensile strength on this sample was also relatively low at 1.38 MPa. No UCS measurements were taken, but it would likely be less than 20 MPa given the results taken from adjacent low density samples. The results of the sonic velocity tests were as follows: • Vp = 2201 m/s (P-wave velocity) • Vs = 1036 m/s (S-wave velocity) Given the low density and tensile strength of this rock sample, it is not likely representative of the typical rhyolite rock mass. The sonic velocity parameters are not used for numerical stress modelling. The P-wave and S-wave velocities are used when calibrating seismic networks and blast vibration monitoring equipment. 1.5.7 Cerchar Abrasivity The Scoping Study (SRK, 2019) provides the results of Cerchar abrasivity for samples of Northern Rhyolite take from WKP68. The Cerchar abrasivity test is used for estimating the life of drill bits on the jumbo and the cutters on raisebore heads. Figure 8 shows that the results of the Cerchar abrasivity tests average 1.5. This is classified as “slightly abrasive”, which is relatively benign. CAI values exceeding 4.0 are classified as “abrasive to extremely abrasive.” Figure 8: Cerchar abrasivity in the Northern Rhyolite
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