2019-10-25_REVISION - M1980244 (11)

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Cripple Creek&Victor Gold Mining Company ■ Squaw Gulch VLF Phase 2A Part 2 ■ Record of Construction Report 475.0106.032 October 24,2019(Revision 1) 3.4.7. Geomembrane Defects and Repairs The CQA Monitor constantly inspected the geomembrane for defects from the time it was deployed until it was covered with DCF. A defect is defined as any item in which a repair is necessary to create a continuously sealed geomembrane layer. All defects were marked with a defect number by the CQA Monitor. Repairs were performed using the extrusion welding method and patches extended at least 6 inches beyond the defect in all directions. All repairs were assigned a repair number and cross checked with defect numbers to ensure that all defects were repaired. All repairs and extrusion welded seams were non-destructively tested using a vacuum box. The area being tested was covered in soapy water and the vacuum box was sealed to the geomembrane. A vacuum was pulled over the area for at least 10 seconds and if no bubbles were present, the test passed. If bubbles were present, the area failed and was marked as a defect.The repair process would then be repeated for the failing vacuum test. Vacuum tests overlapped each other by a minimum of 3 inches. The Geomembrane Defect/Repair Summary, including vacuum testing logs, is presented in Appendix J.7. 3.4.8. Geomembrane Acceptance Prior to DCF placement,the geomembrane was accepted by Tetra Tech,Tezak, CC&V, and the CQA Monitor. All CQA logs and survey data were thoroughly reviewed ensuring that all aspects of the geomembrane installation were performed in accordance with project Technical Specifications. Geomembrane Acceptance Forms are presented in Appendix J.8. 4. PROJECT DEVIATIONS Throughout construction, the following deviations from the Design and IFC Drawings were approved by the Engineer of Record: Several localized grading, underdrain alignment and HVSCS alignment changes were made throughout construction in order to better accommodate the actual site conditions. The grading changes were minor and are presented in the Record of Construction Drawings. IFC Drawings A60 and A62 indicated that a fusion weld should be used between the phased geomembrane connections; however, the use of extrusion welding was also approved. The Engineer of Record accepted the substitution of the CBR Puncture Value test (ASTM D6241) for the Puncture Value test (ASTM D4833) as reported/tested on the geotextile manufacturing certification sheets. P:\Projects\0106.032 VLF2 Phase 2 COA\J-REPORTS\Cert Report-Phase 2A Part 2\DRMS Comments\475.0106.032 CCV PHASE 2A Part 2 ROC REPORT revl.docx Page 14