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Hydropower

Esk Hydro Project, Hawkes Bay

esk6In 2012, a power company developed two high-head power stations in Hawkes Bay, named The Esk Project after the Esk Valley near the site. Maskell supplied the two penstocks in FRP/GRP Flowtite pipe for both the Rimu and Toronui stages of the project.

Maskell was selected for this aspect of the project, as both Maskell and Flowtite have proven experience in the supply of fibreglass pipe for penstocks projects. Flowtite pipe has also been used internationally in both above ground and underground hydropower applications.

Pipe supplied was 2.2km of DN600-DN900 SN10000 and in pressures up to PN25 (25 bar).

Maskell’s considerable experience came into play, as the unstable ground required knowledge in backfill specification and site modifications to pipework as laid. Difficult site conditions, such as significant rainfall and flooding and large irregular rocks and boulders in the streambed meant that bends had to be fabricated during the project to suit the conditions.

Penstocks utilising rubber ring coupling jointed Flowtite pipe provided flexibility in the unstable ground, and the pipe was able to be used for above ground stream crossings, as well as buried service with no corrosion protection.

The GRP pipe bends resulted in significant cost savings for the project, as they did not need to be welded, x-rayed and painted as steel piping would. GRP is also much quicker to lay, with up to twice the length of GRP able to be laid in the same time as its steel equivalent.

This is the third hydropower scheme in New Zealand to utilise fibreglass pipe for the penstocks due to its longevity and corrosion resistance.

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