2019-08-23_REVISION - M1980244 (5)

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Cripple Creek&Victor Gold Mining Company Squaw Gulch VLF Phase 2A Part 1 ■ Record of Construction Report 475.0106.032 August 21,2019 All drill holes were grouted with bentonite slurry or backfilled with native material prior to blasting the crown pillar and remediating the working. 2.2.2. Blasting Blasting was required when drilling indicated that voids existed within 50 feet of the finished subgrade surface. Existing drill holes were loaded, and the working was blasted with the intent to collapse the crown pillar into the voids. 2.2.3. Remediation of Open Shafts and Stopes Open shafts and stopes were remediated by first excavating around the opening to form a minimum slope of 0.5H:1V in the overburden and/or rock. The working was then backfilled with Coarse Shaft Backfill (CSB), when necessary, to approximately 10 feet below the final SLF subgrade surface. The bucket of an excavator was used to compact the CSB surface. A minimum 3-foot thick concrete plug was cast into the shaft, followed by a minimum 7-foot thick layer of Cemented Rockfill (CRF). SF was then placed to finished grade where required. As-built figures for the concrete plugs installed within the Squaw Gulch VLF Phase 2 limits are presented in Appendix D.3. 2.2.4. Remediation of Collapsed Shafts and Stopes Collapsed workings were remediated by excavating the collapsed materials to 25 feet below the final SLF subgrade surface. The excavation was then backfilled with CSB to approximately 10 feet below the final SLF subgrade surface or shaped for the placement of a concrete plug.A minimum 3-foot-thick concrete plug was cast into the shaft,followed by a minimum 7 foot thick layer of CRF. Structural Fill (SF) was then placed to finished grade where required. As-built figures for the concrete plugs installed within the Squaw Gulch VLF Phase 2 limits are presented in Appendix D.3. 2.2.5. Remediation of Laterals All laterals were blasted prior to remediating the working. If the lateral was shallow, the blasted material was excavated, and the working was backfilled with compacted SF. If the working could not be fully removed during excavation, then a geogrid cap was placed 15 feet beyond the limits of the working. In most instances, a two-layer geogrid cap was installed in accordance with Detail 5 on IFC Drawing A38; however, in some areas, a third layer of geogrid was installed based on the working size and depth, field conditions and location of the working within the pad. As-built figures for the geogrid caps installed within the Squaw Gulch VLF Phase 2 limits are presented in Appendix D.3. P:\Projects\0106.032 VLF2 Phase 2 CQA\1-REPORTS\Cert Report-Phase 2A Part 1\DRMS Comments\475.0106.032 CCV PHASE 2A Part 1 ROC REPORT_Revl.docx Page 4