Due diligence and post purchase rehabilitation involving reviews, studies and design related to the projects. Ambuklao comprises a 129 m high central core rock fill dam with 8 x 12.5 m x 12.5 m radial gated ogee spillway, steep chute and flip bucket outlet discharging 11,000 cumecs at PMF, 75 MW underground power station, 327 million m3 storage. Binga is immediately downstream of Ambuklao and comprises a 107 m high zoned earth-rock fill embankment with inclined core, radial gated ogee spillway with steep chute and flip bucket, 100 MW power station, 48 million m3 storage.

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Dam safety audit of the 114 m high main zoned earth rock fill embankment with inclined core, 35 m high north dam and 30 m and 20 m high dykes with gated ogee crested weir spillway (7-16.5 m x 20 m radial gates), chute and flip bucket, 360 MW surface power station, 1,090 million m3 storage.

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Dam safety audit of the 132 m high main zoned earth fill embankment with inclined core and 102 m high secondary embankment with radial gated ogee crested spillway (3 - 8 m x 10 m gates), chute and flip bucket, 100 MW surface power station, 3,000 million m3 storage. Included were the Masiway Re-regulation Dam (25 m high zoned earth fill with central core, 12 MW surface power station and gated spillway (3 radials 11 m x 8.8 m), Canili zoned earth fill division dam (72 m high); and Diayo zoned earthfill diversion dam (64 m high)

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Tonkin & Taylor was engaged, in association with RJ Burnside of Canada, to carry out an Environmental and Social Impact Assessment of this green-field 250 MW hydropower project near the source of the River Nile. The project is being developed by an Independent Power Producer (IPP) under a Build, Own, Operate, Transfer (BOOT) contract. As the project is partly financed by the World Bank Group, the European Investment Bank and international commercial banks, it was subject to the strictest international levels of environmental regulation.

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Tonkin & Taylor was engaged, in association with RJ Burnside of Canada, to carry out an EIA to World Bank standards, of the aquatic impacts of a proposed 70 m irrigation dam in the Lake Tana catchment, at the source of the Blue Nile in Ethiopia. A particular issue was the presence of 15 species of barbel which are known only from this catchment and may be adversely affected by the project.

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Lake Pinot is an impoundment dam storing 500,000 m3 of water for frost-fighting and irrigation of 400 ha of vineyards in the
Waihopai Valley. The dam is located on a permeable gravel formation that necessitated the design and construction of a clay liner across the floor of the reservoir to minimise storage losses.
The dam was designed to compliment the natural environment.

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The Maitai water pipeline was constructed in the early 1960s and is Nelson’s principal water supply pipeline. Tonkin & Taylor was engaged by Nelson City Council (NCC) to complete a geotechnical risk assessment of the pipeline from the Maitai Dam to the Brook Street end, a total length of 8840 m. The assessment was required to assist NCC in determining the risks to the water supply with regard to requirements for pipe upgrades and/or pipeline duplication.

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To undertake an assessment of potential dam sites in the Motupiko Catchment near Nelson. The study was carried out with Landcare Research New Zealand. Sufficient water storage is required to meet the needs of the local farmers for crop irrigation.

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The project involved investigation, design and construction supervision of a silt/flood detention dam at Silverstream Landfill, Upper Hutt Wellington. Extension of the landfill necessitated the decommissioning of existing silt ponds and the construction of a new detention dam.

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Wai-iti Valley Community Dam is a 20 m high irrigation dam storing 800,000 m3 of water and providing drought security for irrigators downstream in the Wai-iti Valley through augmentation of the groundwater resource during times of peak groundwater usage. The dam incorporates several innovation features and has an automated irrigation release and monitoring system.

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Conceptual and detailed design and construction management for the replacement and upgrading of Dam 22, an integral part of the Kinleith Pulp and Paper Mill effluent treatment system. The dam spillway was upgraded to meet current dam safety guidelines.

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Assessment of disposal options for solid waste (sludge) produced by the Kinleith Pulp and Paper Mill effluent treatment system. The study led on to design and resource consents for expansion of an existing sludge disposal landfill and development of a second landfill up valley. The landfills are created by dams across a valley and include dewatering systems to promote consolidation of the sludge.

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Conceptual and detailed design and construction management for the replacement and upgrading of Dam 3, an integral part of the Kinleith Pulp and Paper Mill effluent treatment system. The project also required design and replacement of the stormwater diversion system upstream of the dam, and effluent diversion around the pond and dam to enable desludging.

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The scope of work included Geotechnical investigations, preliminary design, liner site trial and development as well as detailed design and construction observation of the 70 ha 1.5 million m3 Lake Hood recreational lake with associated intake and hydraulic structures. Lake Hood is located on deposits of highly permeable Mid Canterbury alluvial deposits and significant effort was warranted to design an economical liner given the available materials that had a scarcity of fine silt and clay size fractions. A major subdivision with canal access to most lots was associated with the development.

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Delta dam is a 22 m high irrigation dam storing 1.3 million m3 of water providing drought security for a group of wine growers in Marlborough. The dam incorporates a number of innovative features providing a high level of safety at an affordable cost.

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Opuha Dam is located on the Opuha River, near Fairlie in the South Island. It is about 50 m in height and stores approximately 95 million m3 of water for irrigation and hydro electric generation. The dam has proved a significant asset to the district with outstanding contributions to economic development.

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