EGL Ref: 9018 22 June 2022 Page 9 WAI-985-000-REP-LC-0006_Rev0.docx This report shall only be read in its entirety. Peat deposits are found in some of the gullies, e.g. BHN58 and TPN57. These deposits are characterised by a very high organic content and a wet swampy surface, with strengths from soft to firm (25-50 kPa). 4.6. Ignimbrite Ignimbrite deposits have been located in a paleo channel that runs between the dacite outcrops and the eastern rhyolite hills, in a north-south direction, to the east of the Ohinemuri River. This unit includes variably weathered lithic ignimbrite, some of which is completely weathered to a soil. The extent of the ignimbrite is shown in Figure 13. Beneath the existing Northern Stockpile, ignimbrite is present over the dacite. The ignimbrite is poorly welded, characterised by a high proportion of gravel sized lithics, which include fragments of variably weathered rhyolitic pumice, rhyolite and dacite. The ignimbrite varies from slightly to completely weathered. The completely weathered ignimbrite in WG5 has firm to stiff soil strength with Standard Penetrometer Test (SPT) N values from 3 to 11. The slightly weathered to highly weathered ignimbrite rock encountered below 10 m depth has strength ranging from extremely weak to very weak. A core sample from borehole WG5 at a depth of 18 m, had an unconfined uniaxial compressive strength of 1.6 MPa, (refer to the GFR - Ref. 5). Borehole WG5 is the deepest profile of ignimbrite encountered, reaching 30 m without passing through the ignimbrite. 4.7. Boulder & cobble alluvium A boulder and cobble alluvial unit occurs at the base of the ignimbrite flows in some locations as indicated by boreholes WR8 and DH5. Its extent is difficult to determine and in some boreholes the unit logged as alluvium may be a breccia deposit. The alluvium is mainly boulder and cobble clast supported, with a weakly cemented matrix of sand and silt. The boulders and cobbles are mainly rhyolitic and dacitic, ranging from fresh to moderately weathered and are generally moderately strong to strong. 4.8. Rhyolite tuff (Homunga Rhyolite) Rhyolite tuff associated with the Homunga Rhyolite from the Ruahorehore Dome may be found in pockets across the site as shown in Figure 13. It is typically white or light purple, and where unwelded is sometimes sensitive with quick behaviour, and typically has a high water content. It is possible that the rhyolite tuff shown on Figure 13 is the weathered surface of the dacite. 4.9. Rhyolite flow (Homunga Rhyolite) Across the hills of the Ruahorehore Dome there are many variations of rhyolite. This includes rhyolite as lava flows and tuff, with a variety of different textures. Rhyolite
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