The Dam will be a concrete-face rock fill dam. A rock fill dam is a very stable structure that reuses indigenous material excavated from the site and is appropriate for absorbing seismic loads. The Waimea Community Dam will be approximately 53m high, 220m long and 6m wide at the crest. About 430,000m3 of rock will be used to build the dam or be recycled on site. The reservoir lake created by the dam will contain approximately 13.4 million cubic metres of water.
The Waimea Community Dam is designed to the latest international design standards under the NZ Dam Safety Guidelines and has been and continues to be peer reviewed by technical experts.
Design Standards: NZSOLD / ANCOLD / ICOLD: Highest category (High PIC)
Key elements of the dam’s resilient design include:
1. Reinforced concrete facing and a grout curtain into the rock foundation to provide upstream waterproofing.
2. Erosion resistant and flexible rock fill, which enables movement during an earthquake to minimise subsequent failure.
3. Joints to prevent leakage in between the foundation plinth and concrete facing have primary and back-up PVC waterstops.
4. A flow-limiting filter layer under the upstream face to reduce leaks and movement in the dam over time.
5. A spillway that is able to pass water in the maximum probable flood without overtopping the embankment and an upstream debris boom to keep out logs.
6. A system to ensure that if in the unlikely event of a leak, the release of water would be gradual, with water safely carried to the toe of the dam through an open-graded drainage layer of high-quality rock, without causing damage.
7. Dam design standards to ensure it will not release its contents in an uncontrolled manner in a 1:10,000-year earthquake. Modelling of such an event completed by New Zealand and international experts have shown that the dam’s planned drainage layers can accommodate resultant water flows even if there was significant damage to the concrete face and/or
movement of the fill.
Measures to ensure the dam’s resilience and early resolution of issues:
Click here for information about the dam’s Emergency Action Plans.