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Kansai International Airport is located about five kilometers offshore near Osaka, Japan. It is Japan's first airport which operates round-the-clock and it serves an extensive network of international and domestic routes, which makes it one of the international transport hubs in Japan. The aim of the project is to create a human- and eco-friendly airport. The airport should meet environmental quality standards and minimize negative environmental impact on Osaka Bay and surrounding areas. One of the reasons to construct an airport offshore was to reduce air and noise pollution on the mainland. Today's airport has been constructed in two phases. In the first phase (1987-1994) an artificial island was built, on which the first runway is located. The second phase was executed later, for reasons of capacity, between 1995 and 2007. This second phase included the construction of a second artificial island, connected by a road with the first island, and the construction of a second runway. The lessons learned from the first phase were used to optimize the design of the second phase, for construction as well as ecological sustainability.

Building with Nature Design Traditional Design

Right from the start of this project a triple-P approach was adopted. This resulted in a design which includes the creation of new animal and plant habitat in Osaka bay. It also includes the reduction of pollution during the operation phase by e.g. waste water treatment, reuse of treated water, reduction of waste volumes and efficient energy consumption. In addition to the triple-P approach, the design of the second phase is adapted to the lessons learned from the first phase.


In traditional design the environmental and noise pollutions requirements would be just fulfilled and little or no extra effort would be made to create an ecologically sustainable infrastructure.

    General Project Description


    Title: Kansai International Airport 2nd phase
    Location: Osaka bay, Japan
    Date: 1995 - 2007
    Companies: KIAC (Kansai International Airport Co. Ltd.), KALD (Kansai International Airport Land Development Co. Ltd.), specially designated joint venture groups
    Costs: $13 billion
    Abstract: The construction of an offshore airport, including land reclamation and the construction of airport facilities. The purpose is to create a human- and eco-friendly airport that meets environmental quality standards and minimizes negative environmental impact on Osaka Bay and surrounding areas.
    Topics: Land reclamation, integrated and humand- and eco-friendly design, construction and operation of the airport

    Project Objective

    The primary objective is to create an airport that coexists with local communities in a mutually beneficial relationship. The target of the airport island, including all associated businesses and users, is to consider and prevent operation-induced negative environmental and societal impacts.

    Project Solution

    A human- and eco-friendly airport was constructed 5 km offshore in Osaka Bay. By creating the airport offshore air and noise pollution on the mainland are reduced. A further point of consideration in the airport design was the creation of new plant and animal habitat in the ocean. In order to reduce pollution during the operational phase several waste treatment facilities were constructed on the premises of the airport.

    BwN aspects:
    In the design of the airport much effort was spent to reduce negative environmental impacts. Such as the choosen location of the airport and the incorporation of opportunities for new nature in the design.

    Governance context

    Kansai International Airport Co. Ltd. (KIAC) had a leading role in project management. It promoted the project objective, and encouraged voluntary involvement of all airport island-associated businesses. KIAC oversaw and evaluated progress of the project.

    Planning and Design

    Case description:
    The first plans to establish an airport in the Osaka area date back to the 1980's. This offshore airport was constructed on an artificial island in Osaka Bay. The first phase went into operation in 1994, the extension with a second runway, in order to supplement the airport’s facilities and to increase its capacity, was completed in 2007.

    A major challenge in the design of the artificial islands was subsidence. Osaka bay has a soft muddy sea bed on top of a thick clay layer, due to which the artificial islands are subsidence-prone. In order to prevent this subsidence, the design included soil improvement and drainage of the clay layer through sand piles. The lessons learned in the first phase were taken into account to do better and faster in the second phase.

    Like in the first phase, a habitat for seaweed and other vegetation was created at the lower end of the seawall. The lessons learned from creating the seaweed bed in the first phase were used in the design of the second phase. Monitoring results from the first-phase seawall encouraged designers to develop special wave-dissipating blocks with grooves that would enhance spore retention and seaweed adherence. These blocks were placed at a depth that had appeared ideal for the establishment of this type of species on the first- phase seawall.

    Despite the soil improvement works, the artificial island will keep on subsiding after construction. Therefore the facility buildings on the island are equipped with a jack-up system which corrects for uneven subsidence by means of an adjustable foundation.

    BwN aspects:
    Already in the planning and design phase attention was paid to how negative environmental impacts could be avoided or reduced in all later phases. The lessons learned from the first phase were used in the second phase and led to design adjustments.


    Case description:
    The construction of the artificial island for the second runway started with improvement of the soft subsoil, which consists of a 25m thick layer of alluvial clay. Improvement was achieved by topping this clay layer with sand and by creating sand piles in the clay layer for drainage. After the soil improvement a seawall was constructed, which would ultimately protect the perimeter of the reclaimed area. The bayward side of this seawall was built under a gentle slope with grooved wave-dissipating blocks. A 15 m wide horizontal platform was installed at 5-6 m water depth. It was made out of cubical rocks with gutters and concrete blocks of different shapes. Holes were drilled in the concrete for seaweed attachment. In addition, a net and ropes were placed on the surface of the concrete blocks and planted with seaweed. Distributed placement of seaweed-covered blocks taken from the first-phase seawall, enhanced the 'infection' of adjacent blocks with seaweed. The different ways of seaweed planting are illustrated in the figure below.


    After the construction of the seawall the actual land reclamation took place. As the seawall was built before the land reclamation, it acted as a screen preventing turbidity from the landfill material to dispersed into Osaka Bay. On top of this, silt screens were used in an early stage of construction to reduce turbidity in Osaka Bay.

    During construction the workers were provided with a sufficient level of instruction and guidance regarding the importance of environmental conservation and the handling of equipment and materials. Suitable routes were established for trucks transporting construction materials in order to limit the exposure of citizens to noise, vibration and air pollution.

    After the land reclamations had been completed, the airport facilities were built. Several facilities were built to reduce pollution in the operational phase. Environmental impacts are reduced by:

    • Reducing air pollutant and greenhouse gas emissions by the use of ground power units and introducing low pollution vehicles.
    • Reducing water pollutant emissions by advanced wastewater treatment and reusing the reclaimed water in e.g. toilets and for cleaning aircrafts.
    • Reduction of waste volumes and reuse of resources.
    • Using energy effectively, encouragement of energy conservation and introduction of renewable energy.
    • Reducing greenhouse gas emmission by managing the devices that use fluorocarbons.

    During construction works (between 1999-2007) several environmental items were monitored, such as:

    • water quality (daily);
    • the condition of the ocean floor, including a survey of parameters such as grain texture (quarterly);
    • marine organisms, including plankton, fish and rock dwelling organisms (quarterly);
    • seaweed on the seawall;
    • air quality (continuously);
    • impact of project-related traffic on the near-road environment.

    BwN aspects:
    Using grooved blocks on a gentle slope of the seawall creates opportunities for an animal and plant habitat to establish. Different ways of planting seaweed were used, being inserting blocks already grown with seaweed, seeding with spore bags, and seeding with spore and seedling ropes and with the used of wooden boards implanted with young seaweed. Relocation of algal blocks from the 1st phase seawall to the 2nd phase seawall increased the rate of development of the seaweed. Silt protection sheets were deployed throughout the airport island construction area to prevent turbidity.

    Operation and Maintenance

    Case description:
    In the operational phase (since 2007) the same aspects are being monitored as during construction. Also different aspects related to the operation of the airport are measured, such as:

    • terrestrial animal behaviour, such as the flight habits of birds and the migratory routes of hawks;
    • aircraft noise pollution: if the values exceed the agreed limits, measures will be taken.

    BwN aspects:
    In the survey of spring 2004 a seaweed forest of 53 hectares was found on the seawall. Lobsters were found and the number and diversity of fish and shrimp in this area had increased.

    Lessons Learned

    In the first phase of the airport development a good understanding of the environmental system was gained, which was used in the design and planning of the second phase. The lessons learned from the first phase were used in the second phase, both for the construction and for the creation of ecological value. This illustrates the value of learning from projects, among others by post-project monitoring.

    With relatively modest adaptations of the design a significant ecological gain was achieved. One example is the use of wave dissipation blocks with grooves and other surface roughening elements. Different ways of seeding the seaweed and the relocation of algal blocks increased the rate of development of the seaweed.

    Monitoring during construction enabled taking timely measures to avoid undesired situations (e.g. turbidity). Monitoring during the operation and maintenance enables changing operations and avoiding inconvenience to the public or damage to the ecosystem.

    By integrating economic, social and ecological interests in the design, only a small effort can result into a win-win situation for nature and people. In this case more nature is created and pollution and greenhouse gas emission during operation are reduced. The lessons learned here can be used in similar projects.



    • Kansai International Airport Corporation and Kansai International Airport Development Co., Ltd., 2005. 2nd Phase Construction.
    • Kansai International Airport Corporation and Kansai International Airport Development Co., Ltd., 2004. Approach to environmental conservation and creation: striving to make a human and nature friendly airport.
    • Kansai International Airport Development Co., Ltd., 2005. Outline of the 2nd phase project: Supporting the Quest for Tomorrow.


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