COMHAIRLE CONTAE ÁTHA CLIATH THEAS
SOUTH DUBLIN COUNTY COUNCIL
MEETING OF DEVELOPMENT PLAN MEETING
Tuesday, May 04, 2010
HEADED ITEM NO. 89Schedule 4
Schedule 4
To amend Schedule 4 to read as follows (additional text in bold, deleted text struck through):
Casement Aerodrome Baldonnell
Explanatory Note
The County Council policy with respect to Casement Aerodrome Baldonnell differs in two material respects from the policy outlined by the Department of Defence at the time of adoption of the County Development Plan. The differences are as follows;
1. The Department of Defence has stipulated that all existing runways at Casement Aerodrome are categorised as instrument approach runways. However, Council policy excludes runway 05 from this category, and categorises it as a visual approach runway because of the land contours in the approach path.
2. The Department of Defence requires that no new buildings or developments including carparks, workshops, haybarns etc. be permitted on lands lying under the runway approach surfaces at Casement Aerodrome, for a distance of 1,350 metres (4,430 feet) outwards from the future thresholds of the runways. However, Council policy reduces this distance for runway 05 (Rathcoole end) and runway 23 (Corkagh Park end) to that shown on Development Plan Maps i.e. 1,100 metres (3,610 feet). In the document ‘Review of Policy at Casement Aerodrome, Baldonnell, Co. Dublin’ (January 2009), Public Safety Zones have been introduced within the existing ‘red zones’. No development whatsoever is permitted within the Public Safety Zones. However, within the ‘red zones’, some development is permissible whereby the development could not reasonably expect to increase the number of people working or congregating in or at the property. This may include development such as the extension of an existing dwelling or a change of building use. New developments with a high intensity of use would continue to be prohibited and height restrictions would continue to apply to developments in the environs of the Aerodrome. However, Council policy reduces the distance within which no development is allowed on lands lying under the runway approach surfaces, for runway 05 (Rathcoole end) and runway 23 (Corkagh Park end), to that shown on Development Plan maps i.e.1,100 metres (3,610 feet).
S.4.0 County Council Policy, Casement Aerodrome
Casement Aerodrome was constructed in 1917/18 and has since remained in continuous aviation use. It is the only fully equipped military airbase in the State and has served as the main centre of Air Corps operations since 1922. As the principal Air Corps base, it facilitates the vast majority of military training and operational aircraft movements. Approximately 1,250 military personnel and 100 civilians are based at the aerodrome and as such it is a major employer in the area. The last major expansion of the airfield took place in 1954/56 when the existing concrete runways were constructed. In the period from 1977 to 1986 a major upgrading programme was undertaken to modernise aerodrome installations and to facilitate the operation of military passenger carrying aircraft operating to the equivalent of public transport category.
It is a general policy and objective to do everything possible to ensure the safety of military air traffic, present and future, throughout the State and in particular, air traffic at and en route to and from Casement Aerodrome. The policy also has full regard for the safety of persons on the ground as well as the necessity for causing the least possible inconvenience to local communities. The achievement of this policy and objective necessitates, inter alia, some restrictions on building developments in the environs of the aerodrome. The extent of the restriction necessary in any particular instance depends on its purpose. In some cases more than one purpose may have to be served in which case a combination of the restrictions that will satisfy all the purposes to be served is necessary.
In general, restrictions are necessary;
(a) to maintain the airspace around the aerodrome free from obstacles so as to permit aircraft operations to be conducted safely;
(b) to reduce the slight risk to persons on the ground and the increased risk to occupants of an aircraft in the event of the aircraft accidentally touching down outside the aerodrome boundary while taking off or approaching to land;
(c) to eliminate potential sources of interference with the operation of electronic navigation aids;
(d) to obviate possible hazards to aircraft through the generation of smoke, dust or fumes which may reduce visibility;
(e) to control the locations of any activities which may be an attraction to birds,
(f) to limit the extent, height and type of external lighting which may confuse pilots in the clear interpretation of aeronautical lights or which may cause dazzle or glare;
(g) to diminish the nuisance caused to the local communities by aircraft noise insofar as this is practicable.
In the case of (a) above, the dimensions and slopes of the International Civil Aviation Organisation (ICAO) obstacle limitation surfaces that define the limit to which objects may project into the airspace around aerodromes are stated in Annex 14 Aerodromes.
ICAO standards are applied as policy by the Department of Defence at Casement Aerodrome.
The most relevant of the ICAO limitation surfaces are the approach, transitional, inner horizontal and conical surfaces for all runways. These surfaces have been established in relation to Casement Aerodrome for the purpose of this policy.
The existing main runway 11/29 at Casement is categorised as a Code 4 instrument approach runway. and runway 05/23 is a Code 3 visual approach runway, with provision being made for possible upgrading to instrument status. Runway 23 is a Code 3 instrument runway and has two instrument approaches associated with it.
In accordance with ICAO regulations, an instrument approach surface (for runways in excess of 1,200 metres) originates 60m beyond the runway threshold, has an inner edge width of 300m and diverges at a rate of 15% at each side. The surface extends outwards from the threshold for an overall distance of 15km. Restrictions relating to the areas lying under the approach surfaces are detailed later in the policy. At the sides of the runway flight strip there are transitional surfaces which slope upwards and outwards at 14.3% (1 in 7) to a height of 45m above the aerodrome elevation where they meet the inner horizontal surface. The inner horizontal surface is an obstacle limitation surface extending to 4km (in all directions) from the centreline of the runway (or runway strip) at an elevation of 45m above the aerodrome datum elevation. The inner horizontal surface is an obstacle limitation surface extending to 4km (in all directions) from the centreline of the runway (or runway strip) at an elevation of 45m above the threshold altitude of Runway 11’. The inner horizontal surface does not apply where it is above the runway approach and transitional surfaces:
All of these surfaces have been established for Casement and no new objects shall be permitted to penetrate them. The full extent of the restricted areas around Casement is shown on the Development Plan Maps (Please see Explanatory Note to this Schedule).
With regard to (b), if an aircraft should accidentally touch down, it is most likely that this would happen during landing or take-off of a flight. The point of accidental touchdown would in all probability be within or not far outside the boundary of the aerodrome and more or less in line with the runway that the aircraft is approaching or leaving. If an incident of this nature were to take place in the approach area of an instrument runway, it would be apt to be more serious, relatively speaking, than if it took place in the approach to a non-instrument runway, because instrument runways are normally used by the larger types of aircraft and serve by far the most traffic. They are also available in weather conditions that would preclude the use of a non - instrument runway.
Having regard to the slight risk to persons on the ground and the increased risk to the occupants of an aircraft in the event of aircraft accidentally touching down on approaching or leaving a runway, it is highly desirable that the lands lying under the runway approach surfaces, particularly instrument runway approach surfaces, should be kept as free as possible of buildings for some distance outwards from the aerodrome boundary. For that reason, it is policy that no new buildings or developments including workshops, haybarns etc. be permitted on lands lying under the runway approach surfaces at Casement Aerodrome, for a distance of 1,350 metres (4,430 feet) outwards from the future thresholds of runways 11/29 and 1,100 metres (3,610 feet) from runways 05/23. These approach areas are shown on the Development Plan Maps (Please see Explanatory Note to this Schedule). In the document ‘Review of Policy at Casement Aerodrome, Baldonnell, Co. Dublin’ (January 2009), Public Safety Zones have been introduced within the existing ‘red zones’. No development whatsoever is permitted within the Public Safety Zones. However, within the ‘red zones’, some development is permissible whereby the development could not reasonably expect to increase the number of people working or congregating in or at the property. This may include development such as the extension of an existing dwelling or a change of building use. However new developments with a high intensity of use would continue to be prohibited. Height restrictions would continue to apply to developments in the environs of the Aerodrome.
For safety and security reasons, it is also policy that no new development be permitted within the restricted area shown on the Maps and which comprises the aerodrome and lands immediately adjoining the aerodrome boundary. It is appreciated that there are already some buildings in both of these areas but the majority of these pre-date the airport or are in areas where heretofore restrictions did not apply. It is desirable that the existing situation should not be permitted to worsen.
However, objection to the grant of planning permission for domestic extensions to existing dwellings located within restricted areas will not be made provided that
(a) the area of the extension is not considered excessive and in any event does not exceed a fifty percent increase in the floor area of the existing building;
(b) the building is used as a domestic residence only and the proposal does not constitute a change in use, e.g. to bed and breakfast, hotel, or any use of a commercial nature;
(c) the height of the building is not increased.
Elsewhere in the inner zone, no buildings or structures exceeding 20m in height above ground level should be permitted, with further height restrictions related to the ICAO transitional surfaces (which are not shown on the Development Plan maps) from a distance of around 300m (depending on ground elevation) to the runway centrelines, graded down to zero at the edges of the flight strips. However, in view of the volume of helicopter operations and the level and variety of aircraft training movements and for safety and security reasons, planning applications for structures such as high mast lighting, antennae etc. in the inner zone in close proximity to the aerodrome or the runway approaches will be the subject of a special examination to ensure that their construction would not be undesirable for safety, security or operational reasons.
With regard to (c) the electronic aids normally provided to assist in the navigation of aircraft include surveillance and precision approach radars, instrument landing systems, omnidirectional radio ranges, distance measuring equipment, VHF transmitter/ receivers and locators, all of which are sited within or near the aerodrome.
Since the response of electronic equipment can differ greatly depending upon the characteristics of the particular site where it is installed, it is not possible to provide a single set of criteria necessary for its interference-free operation in all cases.
Insofar as the radar installations are concerned, it is necessary that the highest points of buildings or structures in close proximity of the radar antenna should be kept below the level of the radar tower platform. To minimise reflection problems it is necessary that buildings and other structures in the neighbourhood of a radar antenna be constructed of non-metallic materials having low reflectivity at microwave frequencies. No building should block the line of sight from a radar antenna to the airspace in approaches to runways and other critical airspace which can only be identified by the aerodrome Air Traffic Control Service by the Air Corps Communications and Information Service.
An instrument landing system comprises a localiser antenna sited on the extended centerline of the landing runway 200-300m beyond its remote end, and a glide path transmitter sited 150m to one side of the runway, opposite a point on the runway in the region of 300m to 450m inwards from the landing threshold. The minimum building restrictions necessary to obviate interference with the operation of the localisers, glide path transmitters and markers/locators are a matter for the Department of Defence.
Birds are a potential hazard to aircraft during all phases of flight and for that reason the disposal of garbage, offal etc. on lands in the environs at an aerodrome, and any other activity that could attract birds to the environment, including man-made features, is objectionable. Accordingly, the locations of refuse dumps or refuse transfer stations in the vicinity of aerodromes need to be regulated in consultation with the Department of Defence. The County Council should also make known the locations of their own proposed dumps or privately owned and licensed dumps. The County Council shall also make known the locations of any proposed landfill or civic amenity facilities. These requirements exist within an 8 statute mile (13 km) radius circle centred on the aerodrome and no landfill to be within an 8km radius.
Bright external lights above a horizontal plane through the light fittings may be confusing to pilots of aircraft and are likewise objectionable in the vicinity of an aerodrome. Industrial processes that would generate smoke, dust or steam in such volume as would restrict visibility are to be avoided in the neighbourhood of the runway approaches.
Applications by statutory bodies for overhead electricity lines, cross country pipelines and generating stations also warrant special consideration by the Department of Defence.
It is not possible to lay down guidelines for improving safety on existing roads near runway ends. However, in recognition of the slight risks posed by roads crossing runway approaches, particularly where lighting of the roads is included or proposed in the future, the local planning authority should shall consult the Department of Defence about any proposal to build a new road or to improve an existing road where it is planned to run close to the end of or cross the line of any runway. All such roads should be equipped with lighting which does not shine above the horizontal plane.
Casement Aerodrome is the only secure military aerodrome in the State. The requirement for such a facility has been underlined by its use for the highest level intergovernmental tasks and for sensitive extraditions. The arrivals area is not overlooked from any building in close proximity and consequently, there is a requirement to continue the limitation of development in that area and in close proximity to the aerodrome boundary.
The development of lands for residential purposes in areas that are or will be exposed to a high level of aircraft noise is very undesirable from the point of view of both the Department of Defence and future residents. Speculative builders may not be fully aware of the noise nuisance to which residents in these areas would eventually be exposed and individuals and families could unknowingly purchase dwellings only to learn later of the extent of the nuisance and of the inconvenience to which they would be put if it should subsequently be found necessary to insulate their dwellings against noise. The necessity for noise insulation in dwellings being exposed to high levels of noise should be avoided by prohibiting or severely curtailing their construction in areas that are or will be exposed to a high noise level.
A preliminary forecast of aircraft noise in the vicinity of Casement Aerodrome has been prepared for the guidance of the planning authorities and other interested parties. In the forecast, the future level of aircraft noise to which the various parts of the lands in the environs of the aerodrome will be exposed has been calculated. The area within which aircraft noise may be significant is indicated on the Development Plan Maps. If unrestricted residential developments are permitted in areas that are or will ultimately be subject to a high level of aircraft noise, it may be that local residents would seek to impose severe restrictions on aircraft that could seriously interfere with the operation and development of air traffic at the aerodrome.
It is policy that residential development within the noise contour be limited and that in the event of the grant of permission, the occupants be advised that without adequate sound insulation, the level of aircraft noise at the site may be intrusive or annoying.
The same considerations do not generally apply to commercial and industrial developments because of the background noises usually associated with such activities and because such activities are usually carried out in daylight hours and are not normally affected by the problem of noise at night-time. In some cases, however, it might be necessary to incorporate sound insulation in the construction of the buildings to the extent necessary to reduce exterior noise to an acceptable level for the conduct of business within the building.
Temporary structures, including mobile cranes which are likely to penetrate the ICAO surfaces established at Casement must be notified to and meet any requirements set down by the Department of Defence. Where the Council grants planning permissions to developments underlying such surfaces, it shall attach a note requiring that the applicant notify the Department of Defence of plans to erect cranes likely to penetrate the applicable ICAO surfaces and meet any requirements set down by the Department of Defence’
The Department of Defence shall be consulted on any proposed development, which by its nature, is likely to increase air traffic in the vicinity of Casement Aerodrome or affect the safety, efficiency or regularity of operations at Casement Aerodrome.
In conclusion, it is policy to facilitate the continued safe operation and development of air traffic at Casement. It is a requirement therefore that the policy of prohibiting or restricting development within the designated areas around Casement Aerodrome be rigorously enforced. These areas are indicated on the Development Plan Maps
(Please see Explanatory Note to this Schedule).
Reason
In order to reflect amendments recommended by the Department of Defence to update and clarify the information contained in Schedule 4.
Recommendation
That the amendment be adopted.