2. Environmental impacts and protective measures

2.1 Socio-economic structures

Major airports are, as a rule, constructed on the peripheries of densely populated areas. The airport planning should therefore be incorporated into any existing urban or regional planning schemes.

The effects of the construction of an airport on a region's socio-economic structures are many and varied and it is difficult to say where one ends and another begins. The main points are as follows:

- changes in land-use,
- changes in price structures (price of land, food supplies etc.)
- changes of ownership,
- changes in the quality of residential life in the surrounding area,
- changes in occupation structure, which can result in extreme polarisation between the wealthy (international) organisations (hotel chains, restaurants, travel agencies, businesses etc.) and the poorer national surroundings,
- increased land settlement pressure from commercial and industrial establishments and transport companies,
- changes in local job market in terms of qualifications and pay,
- changes in social behaviour

(upward social mobility on the one hand, and corruption, theft, drug dealing etc. on the other).

The extent of these changes can be influenced to some degree by the planning parameters and by an appropriate choice of location. To some extent however these social changes are unavoidable, and can only be alleviated by appropriate supporting measures. To this end, it will be helpful to determine the social structure in the planning area and implement a promotional programme based on this for the population groups affected.

2.2 Ecosystem

Airports represent a serious encroachment on the landscape because of the large tracts of land which are sealed off and because of the far-reaching effects on the surrounding area.

The results of analyses of plant and animal life are a vital consideration when assessing the choice of location. Nature reserves and rare, large-area or interlinked biotopes may be reasons for ruling out locations, if the loss of these areas cannot be compensated for or natural substitute areas are not available. The more successful the efforts to incorporate local natural ecosystems into the new arrangement, the smaller the adverse effects on the surroundings.

Displacement of plants and animals in the areas directly affected by airport facilities and accompanying infrastructure is unavoidable, as a result of construction activities etc. In addition, the site must be cleared of obstacles and it may be necessary to create specific vegetation cover, which will bring different forms of population with it. Special precautions are necessary at airports to reduce the risk to air traffic of bird strike. Such measures are vital and basically involve restrictions on land-use and certain forms of production in the surrounding area. All the environmental conditions in those areas which encourage birds to congregate need to be changed in such a way that they become unattractive as a habitat or as a small-area and frequently visited migratory goal. Common measures include the filling in of bodies of water or their reduction or partition into smaller areas, and the prevention of new bodies of surface water forming. In certain circumstances it may also be necessary to remodel river banks and vegetation and prevent the cultivation of crops which attract birds. It is essential to prevent or close any rubbish tips in the immediate vicinity of airports; they are particularly attractive to birds in their quest for food, and by their nature they provide suitable feeding grounds for other small animal populations, thereby attracting birds of prey, which in view of their size pose an extreme hazard to aircraft in the event of collision, particularly in the area of the engines.

As regards landscape ecology measures, the aim should be to incorporate landscape-related ecosystems into the construction areas, and to distribute the building mass in such a way that the planned system has sufficient surface area available to achieve inherent stability. Inherent stability also has considerable financial significance in that it may reduce the investment and maintenance costs. Ecosystems should be combined within the airport facilities and at the same time they should be connected to the systems adjoining the airport; buffer zones help ameliorate the effects of the necessarily monostructural surroundings of the airport operational areas, bringing an ecological balance to the overall system and integrating it into the surrounding area.

2.3 Airport construction

The construction of an airport generally requires substantial earth movements and large quantities of construction materials.

The environmental impact which unavoidably results should be kept within limits through appropriate planning. The following are particularly important:

- optimisation of transport routes,
- utilisation of natural regional resources (e.g. soil from the surrounding area),
- use of construction materials which are available in the region or locally produced,
- use of local and environmentally aware construction companies,
- ecologically oriented remodelling of drainage conditions.

Airport construction requires a large building site, occupying a large area of land over a long period of time.

2.4 Airports as workplaces

The personnel employed in the operational areas of airports are exposed to safety risks and extreme noise.

The safety risks are to be reduced as far as possible by forward planning measures, e.g.:

- clear identification of transport routes,
- relevant operating instructions for equipment,
- technical supervision of equipment,
- physical and organisational precautions for handling hazardous substances (fuels, working supplies, dangerous cargoes etc.).

In addition, a list should be prepared which includes all hazardous materials which are normally used or frequently handled, giving details of their specific risks, the regulations under labour law concerning the handling of these substances and the emergency medical procedures to be adopted in the event of accidents involving the hazardous substance. The first-aid post must be equipped accordingly.

People who are exposed to extreme noise on the airport site must be protected by appropriate regulations. The corresponding German standards may serve as a guideline in this respect.

2.5 Bodies of water and groundwater protection

Precautions must be taken in the construction engineering to ensure that the groundwater balance and quality are not impaired by the construction and operation of the airport. In addition, the groundwater must be regularly monitored with upstream and downstream wells.

Because the soil is sealed over large areas due to the runways, buildings etc., the rainwater drainage systems need to be planned with particular care. To this end, a quantitative examination of the drainage conditions and the drainage capacities is required at the location selection stage. The basic data (frequency of rainfall, peak loads and frequency) for assessing the necessary rain retention basins and requisite drainage capacities should form part of a climatic survey or of a survey of the flying weather conditions. Likewise, the drainage coefficient of the relevant ground surface types should be taken into account.

Basically it must be assumed that rainwater can be contaminated on all sealed surfaces on the airport site. The runways and taxiways are affected by virtually unavoidable pollutants, foremost among which are: oil residues, fuel residues, de-icing agents (if used), cleaning agents and tyre wear residues.

The airport site must be provided with a sealed catchment and drainage system for rainwater. The collected rainwater is taken to a purification system with oil and petrol separators, before being discharged.

Sewage and wastewater produced on the airport site are led to a treatment system.

At airports, large quantities of substances hazardous to water such as fuels, mineral oils, chemical cleaning agents and solvents are stored, transferred and used. It must be guaranteed that they can be stored in accordance with regulations, and in a manner which is secure against leakage. Appropriate regulations must be established for handling substances hazardous to water, so as to minimise the risk of uncontrolled escape of these materials.

Steps must be taken to train personnel and make them aware of the problems.

There is always a possibility of accidents occurring, in which substantial volumes of substances hazardous to water may be released. There is the risk of contamination of surface water and groundwater alike. For this reason, airports should not be situated in surface water or groundwater conservation areas, especially if the water occurring is used as drinking water.

The gate which separates the catchment area from the retention basin to protect the groundwater in case of accident must be connected to an alarm system and operate automatically; alternatively the manual closure of the gate must be included as an item on a general accident checklist.

The fuel tank farms are to be protected against leakage in accordance with national and international regulations (e.g. collecting basins for escaping fuel), as well as against fire and explosion. Storage containers and pipelines are to be included in a leakage warning system.

2.6 Aircraft noise

Aircraft noise is generally regarded as the "the very worst noise of all", yet the noise pollution inflicted by aircraft on the areas surrounding airports is unavoidable.

Regional planning for the area around an airport must take account of these factors; land-use restrictions (industrial, commercial and residential areas) should be determined for noise protection areas, classified according to a noise level scale to be specified. The slum settlements which can be seen in many countries in the vicinity of airports should be avoided for safety reasons, and should be prevented as far as possible by means of landscaping measures (e.g. by extending the perimeters of the airport, appropriate transport route planning etc.).

The intensity and effects of the noise generated by airport operations are determined by the following factors:

- time of takeoffs and landings (day/night),
- the number of takeoffs and landings,
- the type of takeoff and landing procedures,
- the type of braking technique (reverse thrust),
- the type of aircraft,
- other noise emissions in the airport operations areas (turbine test runs, auxiliary turbines etc.),
- the location of takeoff and landing runways and taxiways.

Noise emissions can be reduced by technical measures such as the following:

1. manufacturer's efforts to reduce engine noise,
2. runway configuration designed taking the surrounding areas into account,
3. sound-proofing measures for fixed emission sources (power plant testing, auxiliary turbines etc.) and
4. measures to protect existing buildings in areas exposed to high levels of noise.

In addition, noise emissions can be reduced through operational regulations:

1. restrictions on takeoff and landing times,
2. specifying approach and departure flight paths, changing these on a regular basis if necessary,
3. using less noisy takeoff and landing procedures,
4. reducing braking by means of reverse thrust,
5. charging higher takeoff and landing fees for older types of aircraft with loud engines (which may lead to less frequent use),
6. operating an aircraft noise monitoring system in order to detect possible contravention of the noise abatement regulations.

At transport policy level too, steps can be taken to reduce noise emissions (switching to other modes of transport, ban on short-haul flights etc.); for further information see the environmental brief Transport and Traffic Planning.

2.7 Traffic noise

The noise generated inside airports by ground traffic is usually negligible because of the extreme spaciousness of the airport installations. The additional noise generated by traffic on the main access roads to airports is normally no higher than that to be expected from general use, provided these roads are efficient.

If heavily used roads pass through areas sensitive to noise, measurements must be taken to determine the overall burden. Protective measures must be taken to deal with the burden as a whole, or alternatively the transport flows must be rerouted. Splitting the traffic flows into a number of less heavily burdened routes is not a sensible approach.

It is a good idea to have low-noise modes of transport (rail systems) serving the airport.

2.8 Air quality

Particularly in areas of high population density, large volumes of pollutants are discharged into the atmosphere every day by traffic, building heating systems, industry and power stations. The emissions produced by an airport are to be regarded as an additive component in the field of ground-level pollution.

The emissions from air traffic and (road vehicle) feeder traffic are very similar in composition, and are technically very difficult to trace to their respective sources. Because of the quantity of emissions produced by aircraft and the air-chemical and meteorological context, it may be assumed that the pollution caused by emissions from air traffic is low compared with the ground-level sources in urban areas. Emissions produced during flights at altitudes of 6-12,000 metres have additional effects whose damage potential has not yet been fully researched.

Increased immissions (HC, CO, NO_x) may occur in the immediate vicinity of airports with large numbers of aircraft movements (and resultant high volumes of feeder traffic), particularly in areas with unvarying weather patterns. It is therefore a good idea to aim towards integrating the airport area into a regional air monitoring system.

If specified limits are exceeded, appropriate administrative measures can be applied to restrict road traffic initially, and also air traffic if necessary.

An assessment of the frequency of inversion weather patterns in the region of the airport should form part of a climate evaluation study, or of a survey of the flight weather conditions.

2.9 Odour

Air traffic may generate unpleasant odours, but these are generally limited to the airfield itself and the immediate vicinity.

Road vehicle feeder traffic likewise generates odours which may cause annoyance, particularly in nearby residential areas.

2.10 Microclimate

Construction activities over large areas generally cause changes in the natural climatic conditions. The main causes, which lead to the formation of a separate microclimate ("town climate"), have to do with the extensive changes to the heat balance, water balance and local wind patterns. The accumulation of pollutants in the air also has an effect. How marked this microclimate is depends primarily on the size of the developed area, the building structure, the terrain and the proportion of open space.

Possible ways of influencing the microclimate in the construction and planning must be determined by means of a climatic survey.