Nature of the modifications
The Resource Management Act requires that the modifications made to the designation, from the designation included in the Waitakere and North Shore District Plans, are identified. Generally, the modifications result in an approach and departure path protection designation for the currently used runways at Whenuapai Air Base that covers a greater area than the designations in the Waitakere and North Shore District Plans, in line with the CAA rules. The most significant modification is a result of the approach and departure path protection having not previously been included in the Rodney District Plan. At the same time, the approach and departure path designation for a third, disused runway at Whenuapai, and the disused runways at Hobsonville, are being removed.
A technical description of the modifications to the obstacle limitation surfaces (referred to as horizontal, conical and transitional surfaces, and the approach and departure paths), which provide the height restrictions for the designation, follows. To make sense of this description, it should be read in conjunction with the designation drawings and diagrams, also available on this webpage. An assessment of the effects of the modification on properties under the surfaces, which is perhaps of more interest, is also provided.
Horizontal, conical and transitional surfaces
The inner horizontal and conical surfaces extend further out from the runways by a maximum of a few hundred metres, in places, than under the legacy district plans. This is due to a change in the CAA rules, requiring the horizontal surface to extend 4000m from the outer edge of the runway, rather than from the centre of the runway. This change means the shape of the surface is more oval than circular. The height of these surfaces has been raised by approximately 5m in the case of the horizontal surface and approximately 10m in the case of the outer edge of the conical surface.
The north-eastern section of the transitional, horizontal and conical surfaces is located over the former Rodney District area and has not previously been designated. The restriction on penetrating the surfaces is therefore new for this area.
Approach and departure path surfaces
The south-west wedge of the approach and departure path surface at the end of the main runway is largely the same shape as in the Waitakere legacy district plan. However, only half of the wedge, lengthwise, was within the former Waitakere District. The north-western half is located in the former Rodney District and has not been previously designated. The restriction on penetrating the surface is therefore new for this area.
The north-east wedge, at the opposite end of the main runway, is also largely the same shape as in the North Shore District Plan. However, the updated designation shows the wedge extending the full 15km from the end of the runway, as required by the CAA rules. It stops at a height of 317.9m above mean sea level (AMSL), just off the coast of the North Shore. In the North Shore District Plan, the length of the wedge from the end of the runway stops at an elevation of approximately 200m (AMSL), at a point approximately above Glenfield Road in Glenfield on the North Shore.
The western wedge of the approach and departure path surface at the western end of the secondary runway was not designated in the Rodney District Plan. Only a length closest to the runway is designated in the Waitakere District Plan. That part of the protection surface that is within the former Rodney District is therefore to be designated for the first time.
The eastern wedge, at the opposite end of the secondary runway, is a wedge shape, rather than a rectangle shape as shown in the North Shore District Plan. The wedge also sits slightly closer to the ground, which may be a result of the older wedge being set at a higher angle than the 2 percent used in the updated designation. As for the main runway, the updated designation shows the wedge extending the full 15km from the end of the runway, as required by the CAA rules. It stops at a height of 316m AMSL, above North Head on the North Shore. In the North Shore District Plan, the length of the wedge from the end of the secondary runway stops at an elevation of approximately 280m AMSL, at a point approximately above Waimana Avenue in Northcote on the North Shore.
Effect of modifications on properties under the surfaces
The modifications to the conical and horizontal surfaces and the approach and departure path wedge surfaces generally have little adverse effect on owners and occupiers of properties under the surfaces. This is due to the height of the surfaces above ground level (the modified areas of the designation are generally at least 40m above ground level), and the fact that the surfaces increase in height as the distance from the runway increases.
The heights of the modified areas of the designation are as follows:
- The modified areas of the conical surface, as a result of the new oval shape, are at least 40m above the ground. The outer edge of the conical surface, which encompasses the additional areas subject to the restriction, is 181.3m AMSL.
- The extended part of the north-east wedge of the approach and departure path surface associated with the main runway is that part which is more than 200m AMSL.
- The north western half of the wedge extending from the western end of the main runway (the part of the wedge that extends over what was previously Rodney District) is at least 40m above ground level.
- The wedge surface extending from the western end of the secondary runway (the part of the wedge that extends over what was previously Rodney District) is at least 60m AMSL, and at least 40m above ground level.
- The heights of the modified areas of the wedge extending from the eastern end of the secondary runway are at least 140m AMSL.
The modifications to the areas subject to the restriction on penetrating the surfaces will therefore not adversely impact those living under it. The heights of the surfaces in these areas are all well above the general permitted activity standards for heights in the legacy district plans and in the Proposed Auckland Unitary Plan. The modifications are also unlikely to affect operators of ‘tall’ structures, such as cell phone towers, electricity transmission pylons, or wind recorders, as the siting of these structures is usually flexible to some degree. Overall, the potential adverse effects of the modifications are considered to be less than minor.
The exception to the above is the horizontal, conical and transitional surfaces in the area to the north of Whenuapai Air Base, between Rangitopuni Stream and Lucas Creek (Riverhead/ Paremoremo/Coatesville area). In this location, the protection surfaces are between 0m and 50m above ground level. In some places the terrain intercepts the surfaces, meaning that any structure would penetrate the surface. The height of the surface in relation to the ground level is shown on the ‘conical’ protection surface diagram numbered GIS-3181995-01.
The designation restriction on penetrating the surfaces does not apply to buildings less than 9m in height. Therefore, single and double storey dwellings and buildings will be allowed under the surfaces, without any additional approvals required. Under the designation, buildings and structures higher than 9m will require the approval of NZDF before they can be constructed. This allows consideration on a case-by-case basis of any proposed penetration, and allows NZDF the ability to turn down any obstacle that would impact on the safe operation of the Air Base.
Under the Rodney District Plan the area is zoned Countryside Living and General Rural. In both zones, the permitted height of a dwelling is 9m. In the General Rural zone there is no height limit for other rural buildings. A similar zoning framework is proposed under the Auckland Unitary Plan. The Rural Production zone would allow dwellings to a height of 9m and other rural buildings to a height of 12m as a permitted activity. In the Countryside Living zone, a maximum permitted height of 9m would apply.
Compared to the permitted activity standards, the designation does impose a greater restriction on other rural buildings in the General Rural zone of the Rodney District Plan, by imposing a 9m height limit where none exists for permitted buildings. This could be considered a more than minor effect. However, the surfaces are more than 30m above ground level over the General Rural zone. The effect of the restriction is therefore not considered to be significant over the General Rural Zone. Further, for dwellings in both zones, and other buildings in the Countryside Living zone, the restriction imposed by the designation is the same as the permitted activity height standard. Any building that exceeds the permitted height will require a resource consent (restricted discretionary activity), and will also require the approval of NZDF. An additional approval process, when one is already required, is considered to be a minor effect, noting that the outcomes of both processes would be uncertain.
It is noted that the modifications to the approach and departure path protection designation do not in any way affect flight activity. The designation restricts obstacles from penetrating the surfaces. They do not authorise any change in use of the runways themselves.
The modifications to the designation have the positive effect of ensuring the flight paths of the two runways are protected, in accordance with the most up-to-date CAA rules. The protection is the same that applies to all airports certified under the CAA rules. The modifications provide for the health and safety of those using the runways, as well as those living under them. The legacy district plans do not provide the degree of protection required.
- GIS-3181995-01 Whenuapai Protection Surfaces - Distance between Terrain and OLS Protection Surfaces
- GIS-3181995-04 Whenuapai Protection Surfaces - Distance between Terrain and OLS Protection Surfaces
- GIS-3181995-02 - Approach Runways [pdf | 312kb | 2 pages]
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