For the raises, existing material was reworked and retested to ensure competent material was constructed on. For the remediation and new construction, unsuitable material was removed until bedrock was encountered. The bedrock required hydro excavation and detailed cleaning with hand-operated tools prior to placement of slush grout and dental concrete in bedrock cracks, fissures, or irregularities. Dental concrete was placed in two different methods dependent on access and size – form and pour or shotcrete. Chimney filters and transition rock were constructed simultaneously with the LPF core. In restricted placement areas, hand operated compaction equipment was used to ensure proper bonding of materials. Placement of rock for the upstream and downstream shells followed lifts of core and filter placement as required. Geotextile was also laid beneath the trafficable surface as part of the design. Compliance with consultant specifications, a stringent quality control program for materials and compaction testing, and effective water management were critical during construction.
Overall length of the dams raised/extended was approximately 500 metres with a volume of 80,000 cubic metres of material moved in 2020.
Sigfusson also drilled, blasted, and crushed materials used during the construction of the dams. With limited notice, a rock excavation of approximately 28,500 m3 was performed including mobilization of all equipment and materials, following all necessary safety requirements, and notifying the appropriate organizations
