Arapuni Dam Foundation Remediation Project

In 2005, an Alliance comprising MRP (Mighty River Power), Trevi, and Brian Perry Civil (Fletcher Construction) installed 95m deep secant pile cutoff panels at Arapuni Dam on the Waikato River, while maintaining a full reservoir. Damwatch was technical advisor to the owner and maintained 24/7 on-site instrument monitoring and surveillance.

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

 

Cosseys Dam Design and Construction Peer Review

Cosseys Dam is a zoned earth fill embankment of 1950s vintage, which initially had no filter materials protecting its core. This water supply dam (south of Auckland, NZ) experienced a number of seepage incidents associated with piping of core material into the underdrain, which necessitated a significant upgrade programme.

Damwatch carried out an independent peer review of the upgrade. This involved attendance at workshops and progress meetings during the investigation and design, and a detailed independent peer review of the final upgrade design.

To read more about the review process and project outcomes, download the case study sheet here.

 

Mokihinui Feasibility Studies

An initial desk top study established the environmental and stability constraints on developing a two dam cascade on the South Island West Coast's Mokihinui River. Damwatch was involved with managing a subsequent feasibility study that identified and investigated a more economically favorable, less physically constrained, lower site. This location, although requiring a larger dam, avoided tunneling by utilizing a channel for diversion. A RCC (Roller Compacted Concrete) dam was proposed on the basis of the hard rock granite and greywacke foundations, the availability of hard rock aggregate and the benefit of using an over dam spillway to pass the PMF. Hazards addressed included: high seismicity with possible proximal active faulting; potential rock slides into the reservoir; potential for landslide dams forming upstream of the reservoir; depth of alluvium at the dam site and large floods.

The hazards have been addressed satisfactorily in accordance with the high Potential Impact Classification of this dam, and an economic development has been conceptualized with consent application presently being processed.

Click here for more information on the Mokihinui Hydro Proposal.