The development of the project began with the removal of the concrete structure. How this was undertaken and the way in which the proposed design aimed to rework and utilise the existing structure was key to its sustainable credentials.
The total amount of removed structures included a 5.86-kilometer-long structure of elevated highway, 5.48 kilometers of concrete, 5.0 kilometers of intercepted sewers, and 0.30 kilometers of sewer culverts. Each stage of construction is detailed below.
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Step 1 Traffic flow management and installation of some safety facilities, including scaffolding for temporary work to get rid of the elevated highway and protective screens |
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Step 2 Removal of the upper plate, horizontal support, concrete in the central section, beams that were cut into pieces, including transporting them to a suitable storage place. |
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Step 3 Cut the elevated highway pier into pieces and transportation. |
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Step 4 Fix intercepting sewers. Build two- lane roads on both sides of the stream. |
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Step 5 Work for re-shaping the stream, landscaping. And installation of lights.  |
As shown in the above cross section of the scheme, the covering structures on both sides of the stream were retained. The surface of structure was adapted to form two-lane roadways on both sides. The space below these structures was used for a combined sewer system to collect wastewater and rainwater. Utilising the existing structure to provide transport routes and reengineer the riverbed dramatically reduced overall material consumption and therefore the cost and carbon emissions attributed to the project.
As Cheonggyecheon was a dry stream, the SMG (Seoul Metropolitan Government) wanted to supply sufficient water to it to create a flow. According to Lee, I.K. (2006), ‘supplying water to the restored stream was one of the most controversial issues, especially over how to secure sufficient water and keep its quality sufficiently good. It was finally decided to supply 120,000 tons of water per day which was required to maintain a depth of 40 cm 0.25 m/sec current average speed.’
Where other river management schemes have utilised the river water to generate electricity this scheme required power to create a flow. This idea of artificial water circulation had been challenged since the earlier stage of the project. In a statement of resignation issued on September 16, 2004, the resigning members of Citizens’ Committee criticised the SMG’s plan as anti-environmental and insisted that the restoration plan should address the restoration of a natural stream, not an artificial stream.
Cho, M.R. (2005) argued that according to the SMG’s estimation, the artificial water streaming of Cheonggyecheon would cost 7 billion won annually and this showed that the SMG’s restoration project was not sustainable. It is important to assess the balance between the initial costs of restoring the ‘heart of Seoul’ and the resulting benefits, culturally, economically and ecologically.
Defining zones within the project area permitted clear objectives to dictate design strategy along different parts of the river. As indicated in the diagrams below the restoration sought to develop three zones with the emphasis on history, culture and ecology.
The history zone ranges from Cheonggye Plaza to Baeogae-dari bridge (1.8 km). Cheonggye Plaza is located at the starting point of Cheonggyecheon matched to the central area of ancient Seoul (Hanyang). The presidential house and many buildings of historical significance are located in this zone. In addition, this area is full of modern high-rise buildings as it includes the CBD. The conflict within this area was to develop a section of the river that facilitated the efficient circulation associated with international CBDs across the world, whilst also preserving sites of historical significance and retaining land to develop and expand limiting interference with floodplain.
Ranging from Baeogae-dari to Dasan-gyo (1.7 km), the culture zone includes big markets and shopping centers along the Cheonggyecheon Stream and is predominantly the center for fashion. In considering economic sustainability in light of the mounting costs of the project this zone will contribute to compensating the governments investment. Further to this considering the project under the principles of new urbanism this zone encourages community involvement and the dissemination of the scheme as a whole. In theory the population of Seoul could live, work and play along the river bank reducing the carbon footprint of each inhabitant.
The ecology zone ranges from Dasan-gyo to Gosanja-gyo bridge (2.0 kilometers). Cheonggyecheon widens and commercial complexes along the stream are rare, instead the area is populated with residential apartments set within an eco-friendly environment. The development of this zone focused on increasing the biodiversity and availability of green space across the area. The provision of a natural flood plain and increased vegetation encouraged the increase in bird and fish species.
