Upgrade of the Mangamahoe Spillway
Author: Gordon Euinton (Riley Consultants) W. Robbins (TrustPower Ltd.)
Presented/Published: 2005
Keywords: Dam, Spillway, Mangamahoe, New Zealand Dam Safety Guidelines.
Abstract:
The Mangamahoe Dam is located on the Mangamahoe stream, a tributary of the Waiwhakaiho River, eight kilometres southeast of New Plymouth. The Waiwhakaiho flows through New Plymouth in a fairly deeply incised valley until it reaches the industrial section of Fitzroy, on the eastern extremity of the New Plymouth. Here valley widens out and there are some light industrial buildings within the flood plain.
The consent permits up to 7 cubic metres per second to be diverted from the Waiwhakaiho into the reservoir, the 4.4MW power station is located fifteen hundred metres north of the dam where the discharge is returned to the Waiwhakaiho. The dam was constructed as a central concrete core wall supported by earthfill shoulders, 25 metres high and 155 metres long in 1930 and 1931. The dam is considered high potential impact by the criteria in the New Zealand Dam Safety Guidelines.
