Matawii Dam

CLIENT

Te Tai Tokerau Water Trust

LOCATION

Kaikohe, Northland

RILEY TEAM

Eli Maynard, Don Tate, Arthur Amputch

THE BRIEF

Matawii water storage reservoir was the first of three reservoirs constructed for Te Tai Tokerau Water Trust. Te Tai Tokerau Water Trust is developing water storage and distribution schemes in the Mid North and Pouto Peninsula that enable a transition to higher value horticultural land use and supplement local town water supplies.

Matawii was constructed between 2019-2023 by MAP Projects Ltd and was the first project nationally to be granted resource consent under the COVID-19 Recovery (Fast-track consenting) ACT 2020. Matawii incorporates the following main structures:

Zoned embankment dam up to 25m high and 550m long.
1.8m diameter main conduit housing two intake/outlet pipelines and dewatering gates.
Intake fish screens with winched retrieval system.
12m wide concrete service spillway.
45m wide grassed auxiliary spillway.

Matawii dam has a high potential impact classification.

THE OUTCOME

Riley was the primary engineering partner on the project. We provided geotechnical, dam engineering and construction expertise from conception to commissioning.

Matawii reservoir can store up to 710,000m3 and is filled by a combination of catchment and pumped inflows. Key design features include:

Dam built using site-won volcanic soils and founded on Kerikeri Volcanic Group Balstic Andesite.
Foundation preparation involved curtain grouting and dental concrete in the central part of the dam
Vertical chimney drain.
Three-layer blanket drain in the main valley section and a series of strip drains on the abutments.

The dam commenced filling in March 2023 and is almost full.