Arapuni Dam Foundation Remediation Project.

Arapuni Alliance - Brian Perry Civil, Damwatch Services, Mighty River Power and Trevi S.p.A.

The rock foundations of the Arapuni Dam had major clay-filled fissure zones with the potential to erode out. This could result in an expensive loss of water and foundation pressures high enough to erode the abutment of the 64-metre-high dam with disastrous consequences.

The four zones of fractured rock were sealed with curtain walls formed by drilling overlapping (secant) holes right down through the dam and backfilling them with concrete while keeping the power station fully operational.

The Arapuni Dam foundation remediation project wins the Supreme Award for New Zealand Engineering Excellence because of its high degree of technical difficulty, the originality of the solution, its contribution to the reputation of New Zealand engineering internationally, and the beneficial effects to New Zealand of keeping this dam operational.

The project is a major international first, and the engineering team made great efforts to ensure that the construction work did not harm the structural or operational functionality of the dam, and that the responses of the foundation to the construction did not portend a dangerous or critical situation. The professionalism shown throughout by the dedication of the Arapuni Alliance to quality was outstanding.

For more information on this project, download the case study sheet here.