What is Proposed?
THE PROPOSAL:
Investigation of the Island favoured a site at the Western end of the island set in land form the coast and estuary so a wind barrier of trees could buffer any strong winds and to avoid influencing the beach, the birds and current public areas.
The course would consist of a 2.5km stretch of water 135m wide and 3.5m deep in the racing section. This will allow for 8 racing lanes for rowing and kayaking, with a movement lane along the edge.
A 750m by 50m by 2m deep section would “protrude” from the western end of the course for the dual purpose of a slalom skiing course and holding area for regattas. This area would have a small island separating the main course from the skiing course to reduce wind fetch and wave build-up on either course.
A feed channel is proposed to deliver water from the inlet near Mapua. This area is suggested at this time because due to the high tidal flow it is already tolerant of high energy and will supply a high volume of water at any one time to flush or fill the course. The course would be subject to tidal flow with water being held in the course by control weirs which would be designed so that it could be filled, flushed or drained as required. The weir is also intended to double as a foot bridge for walkers and cyclists.
During rowing and kayaking regattas the skiing course would be used as a warm up and start collection area for the competitors. Likewise during a skiing event they would have their own dedicated water to use for the event and for practise. The skiers are fortunately aware of any potential issues regarding noise. However the low number of active boats during a skiing practice or event and the quality of today’s boat engines has alleviated some of the trusts concerns about undue noise. This will however be tested in due process.
The spoil excavated from the course would be shaped in terraces on the course edge up to approximately 6m in height to provide public viewing areas in the finishing zones. Outside the viewing zones the spoil will be shaped as 6m to 8m “dunes” mimicking the Islands previous habitat although on top of the terraces and dunes tall trees would be grown as an extra wind buffer. Other than this “bump” of growth the average visitor to the island would not be able to see or even be aware of a course. It would only be visible from the air.
The course will be designed to fit into the natural theme as much as possible with its surroundings grassed and vegetated in native vegetation.
The edges of the course need to be able to absorb any boat washes to comply with international standards. This can be achieved by aquatic plantings along the high water mark and/or irregularly shaped cobbled zones along the waters edge. Because of this the only concrete on the course will be at boat launch points and the control gates. It is intended to keep the number of permanent structures to an absolute minimum.
Buildings such as the start and finish towers will be obvious, however their scale is minimal. The start tower would have a footprint less than 10 m², while the finishing tower and control room would be around 20 m². It is hoped that buildings such as the boat holding shed will be built into the spectator viewing terraces so only the doors are visible.
The length of the course will have a cycle track down one edge for coaches and for the triathlon/duathlon events. The area around the finishing line will also be able to cater for spectators and competitors of a triathlon/decathlon transition area.
There are a number of engineering considerations on the feed channel and course itself which have been discussed with engineers. There are a number of ideas so we are not suggesting anything here at the moment but if you have a constructive suggestion then please forward it to us. The engineering issues will obviously be looked in greater detail in the feasibility study and prior to the resource consent.
From being completely empty to completely full at a high tide the course and feed channel would require approximately 1200000m3 of water. The estuary has a daily flow of approximately 6200000m3 of water (Nelson State of the Environment report, 1993). The course would therefore require approximately 1.8% of the total flow to fill it. If the weir was designed to hold half the water for use on a daily basis then to fill it would obviously only require 0.9% of the flow.
