EGL Ref: 9215 23 June 2022 Page 33 This report shall only be read in its entirety. File: WAI-985-000-REP-LC-0002_Rev0.docx. FIGURE 27: STORAGE 1A UPSTREAM CUTOFF AND TAILINGS UNDERDRAIN HISTORIC FLOWS Leachate drain flows indicate the amount of groundwater passing through the embankment. Figure 28 shows the flows for the leachate drains associated with Storage 2 and includes drains which are beneath the Central Stockpile and Northern Stockpile. What is evident from the data is that most of the leachate drains have very little flow. This is because the Storage 2 embankment surface is now lined on its surface with a lower permeability layer, which limits groundwater and air infiltration. The two drains that still respond to rainfall are L10 and L11. L10 is located largely in the footprint of the Northern Stockpile which is not capped. L11 partially underlies the footprint of the Central Stockpile which is still being filled and is also not capped. This indicates the effect of the capping layer. Once fully capped Storage 1A is expected to experience the same effect. FIGURE 28: STORAGE 2 HISTORICAL LEACHATE DRAIN FLOWS
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