A Massive Tunnel Beneath Gangnam Station... Seoul City to Begin Construction of Deep Drainage Tunnel by Year-End

Gangnam Station, Dorimcheon, Gwanghwamun Stormwater Drainage Tunnel
Design Qualification Review Completed, Ventilation Shaft Construction
Economic Feasibility Review After 6 Months of Detailed Design Implementation

The Seoul Metropolitan Government is set to begin construction of the 'Deep Underground Stormwater Drainage Tunnel' in the Gangnam Station, Gwanghwamun, and Dorimcheon areas. The 'Deep Underground Stormwater Drainage Tunnel' is a facility that creates a large tunnel 40 to 50 meters underground to store stormwater during heavy rains and discharge it into rivers.

According to Seoul City on the 10th, the city held a design evaluation meeting on the 30th and 31st of last month for the comprehensive bidding design qualification review of the 'Deep Underground Stormwater Drainage Tunnel Construction Project' and gave a qualification approval for the basic design of each project and the detailed design of the priority construction sections.

Previously, Seoul City held joint briefing sessions and technical review meetings for the Hanshin Engineering Consortium (Gangnam Station), Daewoo Construction Consortium (Dorimcheon), and DL E&C Consortium (Gwanghwamun), which submitted single bids, and completed the final design evaluation. To enhance transparency and fairness in the evaluation, the design review subcommittee was composed of a total of 18 review members. Two members from the Ministry of Land, Infrastructure and Transport’s Central Design Review Subcommittee also participated.

The Gangnam Station, Dorimcheon, and Gwanghwamun projects, which were approved in this review, will each undergo a six-month detailed design phase, followed by a design economic feasibility review (VE) and detailed design qualification review before signing the main construction contracts. Construction on the priority sections with completed detailed designs will begin in December. For Gangnam Station and Gwanghwamun, temporary facilities and excavation work for the ventilation shafts will be prioritized, while for Dorimcheon, temporary facilities and excavation work for the inflow settling basin and temporary facilities for five vertical shafts will be prioritized.

Kim Chang-hwan, Seoul City’s Technical Review Officer, stated, "To prevent urban flooding caused by abnormal climate conditions and to protect the safety of citizens, we will thoroughly verify and manage the upcoming design and construction processes."