to their construction. For the vent raises we have assumed that drainage can occur for 40-60 days (depending on the depth) prior to sealing inflows. Structural Defect Inflows Inflow from fracture and fault zones have been calculated using a transient analytical model (Lohman, 1972) as follows: Where: Q Inflow to one side of the tunnel (m3/d) L Length of tunnel (m) K Average horizontal Permeability (m/d) S Specific Yield b Saturated aquifer depth (m) ho Head above tunnel (m) t Time (days) Fracture inflows were assumed to be allowed for 7 days prior to them being grout sealed. The results from these vent and fracture models have then been aggregated into the rock mass inflows at the relevant distance along the tunnel alignment to provide the total expected inflows. B.2 Description of Modelled Scenarios The following provides the tunnel metrics that have been assumed in the groundwater inflow assessment. Dual Access Tunnels - Willow Farm to WUG The proposed tunnel option consists of a single tunnel from the portal at Willows Farm, transitioning to dual tunnels from the first vent raise through to WUG. The dual tunnels consist of the metrics provided in Table B1. Table B1 WUG Dual Tunnel Metrics 6,877 m Tunnel to access upper orebody 1,231 m Tunnel to access lower orebody 5,561 m Tunnel return air tunnel parallel to main tunnel 1,020 m Stockpiles 120 m Sumps and pump stations; 51 m Ventilation access drives 14,860 m Tunnel Sub Total The inflows resulting from a dual tunnel have been derived by simulating a single tunnel and twin tunnel scenario in SEEP/W under various head conditions. This has enabled a factor to be determined that is applied to the analytical model values for the dual part of the tunnel (1,400 m to 7,000 m). This factor is approximately 10% inflows based on a tunnel separation of 30 m.
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