Background Preliminary numerical groundwater modelling has been undertaken to assess a number of the project components to assess groundwater inflows and extent of drawdown associated with dewatering. The following provides a high-level overview of the SEEP/W numerical modelling undertaken. EG Vein Model Model Setup The EG Vein model has been constructed as a 2-dimensional model oriented perpendicular to the main vein system (NW-SE). The model is 950 m wide and has an approximate 50 m x 50 m grid spacing and smaller locally. The model set-up is shown in Figure A1. Figure A1 EG Vein Model Setup Material Properties The model was setup as replicating a soil regolith layer overlying a rockmass. The regolith was assigned a permeability value of 1x10-6 m/s. The rockmass permeability was varied within a range of permeability values as measured for the rhyolite rockmass from K= 8x10-8 m/s (weathered volcanics) to K=1.0x10-6 m/s (fractured volcanics). The regolith was assumed to have a Storativity of 0.15 and the volcanic rockmass to be 0.01. Boundary Conditions The model boundary conditions assigned are as follows: - LHS Constant head = 174 m RL - RHS Constant head = 174 m RL - Rainfall Recharge = 10% - Mine = Seepage review – 300 m RL
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