Construction of the Waitaki dam and powerhouse started in 1928. It continued as a ''make work'' project through the Depression and generated its first electricity in 1935.
Now owner Meridian Energy has announced plans for a four-year project to upgrade the dam and powerhouse, following completion of a $67 million project, started in 2008, at the Benmore powerhouse.
The Waitaki dam upgrade has been mooted for about 10 years and detailed planning has proceeded over the past five years.
It is part of a long-term programme by Meridian which will include other Waitaki hydro-electricity generation facilities and is not related to the decision last month to delay building the north bank tunnel scheme on the lower Waitaki River because of a lack of demand for electricity. The Waitaki dam has six 15MW generating units, producing up to 500GWh of electricity a year - enough for about 62,000 average homes.
Part of the project includes reinstalling a seventh unit to match the original generating capability, adding another 15MW to its potential capacity.
Work would start in April, be managed by Meridian and involve 40 to 50 contractors.
Meridian's general manager markets and production, Neal Barclay, said yesterday the project would ensure the Waitaki dam, despite being almost 80 years old, would continue to provide reliable and sustainable electricity.
A range of work would ensure the old powerhouse building remained strong and usable. This work included earthquake strengthening, but the architectural look of the building would be retained.
Protection would be upgraded for the generating units, so faults would be identified and rectified as early as possible.
Outside the site, access from the State Highway 83 intersection would be made safer. Erosion, seismic and flood protection work would be done around the site.
''This is business-as-usual maintenance that will give us increased flexibility. We will continue to operate within our water consents and will continue to generate a similar amount of power,'' Mr Barclay said.
Meridian envisaged the work would have little impact on the community. There would be long periods when locals would not notice any additional activity on the site.
Public access to the dam and powerhouse would be limited, for health and safety reasons. The viewing areas, off SH83 above the powerhouse, would not be affected.
At times during the project there would be an increase in the amount of traffic entering and leaving the site.
''At any one time there will be a couple of dozen extra people on site and ... there will be increased traffic with some significant loads accessing the site. A traffic management plan will help us minimise any disruption and we will keep the community informed,'' he said.
Meridian did not anticipate any impact on the river flows or the recreational use of Lake Waitaki or the Waitaki River.
A database is being developed of people who would like to be kept up-to-date during the project. Anyone interested can email hydro.info@meridianenergy.co.nz.
Behind the dam
Waitaki dam and powerhouse
• Work started 1928Up to 1000 workers lived on site
• Concrete dam 36.5m high, 353m wide
• Powerhouse 152m long, 45m wide
• Officially opened October 27, 1934
• Generation started 1935
• Originally 7 generating units
• Last major upgrade 1954.
