Geological Consulting has supported Stantec on several New Zealand dam safety projects. They have provided desktop studies and site investigations; where a good understanding of the local geology, dam and foundation materials, instrumentation, and wider dam safety issues including flooding, internal erosion and seismicity has been required. They have consistently exceeded expectations in terms of technical delivery, programme, safety, and end-client satisfaction.
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Project
Opuha Dam – Auxiliary Spillway Improvements
Client: Stantec New Zealand
Location: Canterbury, New Zealand
Date: 2020
Stantec New Zealand (Stantec) was engaged by Opuha Water Limited (OWL) to undertake the design of improvement works to the auxiliary spillway of Opuha Dam, located around 12km northeast of Fairlie, Canterbury. The approximately 45m high clay core rockfill dam was constructed in 1999, and has a service spillway on the right abutment of the dam and an auxiliary spillway located on the left abutment of the dam. The auxiliary spillway comprises a short approach channel, two fuse plug embankments designed to fuse at different flood levels and a short unlined rock chute.
Geotechnical investigations were completed to support the design of the spillway improvements, for which Geological Consulting was engaged by Stantec to provide technical advice and site supervision. The investigations included drilling within the different material zones of both the main embankment and the fuse plug embankments. This includes the dam core and filter materials, to confirm their as-built details and material characteristics. A key consideration for the work was dam safety, which was undertaken in accordance with the requirements of the New Zealand Society on Large Dams (NZSOLD) Dam Safety Guidelines (2015) and other industry guidelines for drilling in and around dams (ANCOLD 2020, FERC 2016, USBR 2014, etc.).