2020-08-07_REVISION - M1980244 (5)

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Cripple Creek&Victor Gold Mine ■ Valley Leach Facility 2 Phase 3 ■ Detailed Design for Permitting,Revision 1 NewFields Project No.475.0106.033 July 2020 Subsequent laboratory analyses were completed as part of the investigation. 3.2. Site Geotechnical Conditions Subsurface conditions encountered at each boring location are indicated on the individual logs from the geotechnical investigation, presented in Appendix B. The locations of the borings, completed for this design effort are shown on Drawing A03. Stratification boundaries on the boring logs represent the approximate location of changes in material types. In situ, the transition between material types may be gradual. Six boreholes in the proposed footprint of the VLF2 Phase 3 expansion were completed. The boreholes were drilled using a CME 550X ATV mounted drill equipped with 5.5 inch (outer diameter) ODEX down-hole air hammer. The drill rig was owned and operated by Authentic Drilling, Inc. and under full-time supervision of NewFields while on-site. Driven samples were retrieved using a Standard Penetration Test (SPT) split-spoon sampler (2- inch O.D. / 1.5-inch I.D.). A 140-pound automatic trip hammer with a drop height of 30-inches was used to drive the samplers. Blow counts from the standard penetration test (SPT) are commonly used to estimate the engineering properties of soils such as strength or compressibility characteristics. The average SPT n-value of the subsurface, excluding samples that hit refusal, was 19 blows per foot within the upper 15 feet of the subsurface. The data can be interpreted qualitatively and indicates that in general the subsurface comprised of medium dense to dense cohesionless soil deposits. NewFields personnel logged the subsurface conditions based on the materials recovered from the driven samples and soil cuttings blown to the surface. Samples were classified using the Unified Soil Classification System (USCS) that divides the soil into similar groups with similar engineering characteristics. Photographs of soil samples are included in Appendix B. Based on conditions encountered in the boreholes, the general subsurface profile consists of 26 to 62 feet of gravels and sands over phonolite bedrock. Bedrock was encountered in borings BH- 03 and BH-05 at 45 and 30 feet, respectively. Groundwater was encountered in boring BH-05 at a depth of 35 feet. The results of the site investigation indicate that the foundation subsurface conditions are sufficient for construction of the VLF2 Phase 3. 3.3. Laboratory Testing Program Samples obtained from the site investigation were tested for index properties at the geotechnical laboratory on-site for the VLF2 Phase 3 construction. The purpose of the testing programs was Page 5