Our Ref:9049 7 March 2022 Page 1 File: 9049 Appendix - 7 Mar.docx TABLE A1 Material Deformation Parameters Unit Unit Weight (kN/m3) Young's Modulus (MPa) Poisson's Ratio Regolith 18 1,000 0.2 Weathered Andesite 22 1,000 0.2 Unweathered Andesite 27 8,700 0.2 A3.2 Vent Shafts There are 5 vent shafts in total and are identified as shafts 1 - 5. Vent shafts 2 – 5 are located at WUG and shaft 1 is located at Willows Road Farm. This section includes both models at Willows Road Farm and WUG. The vent shafts were modelled as axis-symmetric, large diameter wells. The depths of the vent shafts are provided in Table A2. TABLE A2 Vent Shaft Depths Vent Shaft N.o Depth (m) 1 WUG 200 2 WUG 320 3 WUG 220 4 WUG 150 5 WUG 195 Only Vent Shafts 1 and 2 are modelled in SEEP/W and SIGMA/W. Vent shaft 1 is modelled for Willows Road Farm and Vent Shaft 2 is modelled as the deepest vent shaft at WUG. Figure A3a and Figure A3b provides the model geometry and the associated boundary conditions for the Willows Road Farm vent shaft assessment base condition (i.e. before vent shaft construction). The seepage SEEP/W analysis assumed one permeability condition. SIGMA/W deformation model was applied as three different stiffness layers. From the surface these layers were: regolith, weathered andesite, and undisturbed andesite. The model base extends from RL225m down to RL-275m. The parameters summarised in Table A3 have been adopted for SIGMA/W deformation analyses from the dewatering of the vent shaft at Willows Road Farm. TABLE A3 Material Deformation Parameters for Shaft 1 Material Layer Unit Weight (kN/m3) Young's Modulus (MPa) Poisson's Ratio Regolith 18 30 0.2 Weathered Andesite 22 1,000 0.2 Undisturbed Andesite 27 8,700 0.2 Figure A5a and Figure A5b provides the model geometry and the associated boundary conditions for the WUG vent shaft assessment base condition (i.e. before vent shaft construction). The model was constructed as five layers. From the surface these layers were:
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