ANNEX D1 BASIC CONSIDERATIONS FOR REVIEWING STUDIES IN THE DETAILED RISK ASSESSMENT FOR SAFETY

ANNEX D1 BASIC CONSIDERATIONS FOR REVIEWING STUDIES IN THE DETAILED RISK ASSESSMENT FOR SAFETY

ANNEX D1: BASIC CONSIDERATIONS FOR REVIEWING STUDIES IN DRA FOR SAFETY D1-1 ANNEX D1 BASIC CONSIDERATIONS FOR REVIEWING STUDIES IN THE DETAILED RISK ASSESSMENT (DRAs) FOR SAFETY PARAMETERS Text of geotechnical report 1. Has the location of the mining operation, or a map indicating its location, been included? 2. Is a summary of the scope and purpose of the study provided? 3. Is a concise description of the area s topography and geology provided? 4. Is there a list of the laboratory tests and field studies on which the report is based? 5. Are the general features of the subsoil, rocks and groundwater described? 6. Is the following information (generally provided in appendices) included? a) Records of drilling and test drilling b) Soil profiles c) Laboratory test data d) Photographs Underground plans and profiles 7. Does the report provide underground plans and profiles of the study area? 8. Do the plans include the findings of the field investigation? 9. Does the report meet the minimum criteria regarding points to be studied, as detailed in Table 5.2? 10. Do correctly numbered drill holes and shafts appear on a plan, with indications of elevation and location? 11. Does the underground profile contain a textual or graphic description of the types of soil and rock present? 12. Does the underground profile show groundwater levels and date of measurement? Record of test drilling results, or underground profile

ANNEX D1: BASIC CONSIDERATIONS FOR REVIEWING STUDIES IN DRA FOR SAFETY D1-2 13. Is there a record of the depth and type of samples taken from test drilling? 14. Are the results of SPT testing, percentage of recovery of the sampled core material, and RQD values provided? 15. If CPTs have been performed, are charts provided showing cone strength and angle of friction as a function of depth? Laboratory data 16. Were the laboratory tests for the classification of soils (e.g., moisture content, gradation, Atterberg limits) performed with representative samples to confirm the on-site visual identification of soils? 17. Are the results of laboratory tests (cut resistance, consolidation, etc.) included or summarized?

ANNEX D1: BASIC CONSIDERATIONS FOR REVIEWING STUDIES IN DRA FOR SAFETY D1-3 A. INFORMATION REQUIRED TO PERFORM DETAILED SUBSIDENCE RISK ASSESSMENT 1. Is settling, subsidence or other failure associated with underground operations described? 2. Is the type of underground operation (room and pillar, etc.) described? Estimation of geological parameters 3. Have the following field tests been performed to ascertain the presence of voids, and the characteristics of the underground strata? a) GPR (Ground Penetrating Radar) b) TDR (Time Domain Reflectometry) c) Resistance analysis d) Gravity surveys e) RQD f) Shear strength parameters 4. Have studies been made to determine the depth and profile of the underground aquifer? 5. Have studies been made to ascertain drainage patterns in the area of the mine, and have the patterns been indicated on a map? 6. Is the geometry of underground works and access adits to the surface available? 7. Is there a verification of the rock mass strength and general stability, based on the dimensions of rock bridging, pillars, stopes, etc.? 8. Are estimates provided of the area that could be affected by subsidence?

ANNEX D1: BASIC CONSIDERATIONS FOR REVIEWING STUDIES IN DRA FOR SAFETY D1-4 B. INFORMATION REQUIRED FOR PERFORMING DETAILED STABILITY RISK ASSESSMENT 1. Is the existence of sliding, settling, erosion, flows of liquids, or other failures in the operating area described? 2. Is there a description of measures that are in place at the site to protect against erosion? Estimation of geotechnical parameters 3. Have the following field or laboratory tests been performed to ascertain the properties of the material of the dump and its foundation? a) Standard penetration tests (SPTs) b) Cone Penetration Tests (CPTs) c) Classification of the material of the deposit, founding material, moisture content, specific gravity, angle of repose d) Liquid limit, plastic limit, index of plasticity 4. Have studies been made to determine the phreatic surface in thedam? 5. Have permeability tests been made in the field and in the laboratory? 6. Are the details of the calculations of the operation s safety factor provided? 7. Is there mention of the design criteria for which said safety factor was calculated (seismic activity, moisture, etc.)? 8. Are the embankments designed with a minimum pseudo-static safety factor of 1.2? 9. Are estimates of the distances or areas of influence of the simulated failures provided?

ANNEX D1: BASIC CONSIDERATIONS FOR REVIEWING STUDIES IN DRA FOR SAFETY D1-5 C. INFORMATION REQUIRED TO PERFORM DETAILED SLOPE FAILURE (COLLAPSE OF PIT) RISK ASSESSMENT 1. Is the existence of sliding, settling, erosion, or other failures in the operating area described? 2. Is there a description of measures that are in place at the site to protect against erosion? Estimation of geotechnical parameters 3. Have the following field or laboratory studies been performed to determine the properties of the in-situ rock mass conditions? a. RQD b. Confined compression tests c. Geological map of cracks, faults and fracture systems d. Orientation of faults, shears and defects 4. Have studies been performed to determine the phreatic level in the pit s slopes? 5. Are the details of the calculation of the safety factor in the pit s slopes provided? 6. Is there mention of the design criteria for which said safety factor was calculated (seismic activity, moisture content, etc.)? Probability of seismic disturbance incorporated in design? 7. Are estimates of the distances or areas of influence of the simulated failures provided?

ANNEX D1: BASIC CONSIDERATIONS FOR REVIEWING STUDIES IN DRA FOR SAFETY D1-6 D. INFORMATION REQUIRED TO PERFORM DETAILED RISK ASSESSMENT FOR COLLAPSE OF TAILINGS STORAGE FACILITIES 1. Is the existence of sliding, settling, erosion, or other failures in the operating area described? 2. Is there a description of measures that are in place at the site to protect against erosion? Estimation of geotechnical parameters 3. Have the following field or laboratory studies been performed to determine the properties of the tailings deposit? a) Standard Penetration Tests (SPTs) b) Cone Penetration Tests (CPTs) c) Particle size analysis, moisture content, specific gravity, permeability d) Properties of foundation soils e) Liquid limit, plastic limit, index of plasticity 4. In connection with tailings, have studies been performed to determine the phreatic level in the wall and reservoir? 5. Have studies been performed to determine the drainage pattern in the area? 6. Has pore pressure been estimated? 7. Are details of the calculation of the deposit s safety factor provided? 8. Is there mention of the design criteria for which said safety factor was calculated (seismic activity, phreatic level, etc.)? Probability of seismic disturbance incorporated in design? 9. Is the tailings deposit designed with a minimum pseudo-static safety factor of 1.2? 10. Are estimates of the distances or areas of influence of the simulated failures provided?