'Issues found during verification addressed through the process'

89% of core method's constructability confirmed; project to proceed on schedule

A rendering of Gadeokdo New Airport [Busan city government]
A rendering of Gadeokdo New Airport [Busan city government]

The Daewoo Engineering & Construction consortium has rebuffed allegations of a rushed approval for the Gadeokdo New Airport project, saying it disclosed issues identified during verification of the ground improvement method and incorporated solutions into the basic design.

The consortium said Wednesday that it had "transparently disclosed some of the problems and challenges that emerged during the constructability verification of the offshore prefabricated vertical drain method," adding that "specific technical improvement measures to address them have been fully incorporated into the basic design report submitted to the Public Procurement Service and the project owner on Sept. 7."

The statement responded to allegations that the Ministry of Land, Infrastructure and Transport had approved the basic design despite technical problems identified during verification of the offshore prefabricated vertical drain — the core ground improvement method for the airport — raising concerns that the project was being pushed through hastily. The prefabricated vertical drain method involves inserting drainage material into soft ground to allow water to drain from within the soil.

The consortium conducted constructability verification at five offshore sites — a total of 90 boreholes — at the actual planned construction locations from July 23 to Aug. 16. Constructability was confirmed for the standard prefabricated vertical drain improvement zone, which accounts for 89 percent of the total offshore volume. The consortium noted that the runway is also located within this zone.

However, in the hard prefabricated vertical drain improvement zone, which accounts for the remaining 11 percent, some instances of penetration stoppage and deformation were observed while passing through an intermediate sandy soil layer.

Having identified the penetration stoppage issue in that 11 percent zone, the consortium said it had already incorporated into the basic design a measure to enhance penetration force through the intermediate sandy soil layer.

The consortium said the verification results and improvement measures — including the penetration-force enhancement plan — had been reflected in the basic design report. A second round of constructability verification to address the remaining issues is also being prepared.

The consortium also highlighted the scope of its ground survey work. Its offshore ground survey covered 97 boreholes — more than five times the 19 boreholes conducted by the earlier Hyundai Engineering & Construction consortium. Based on that data, the design targets both the upper and lower clay layers for prefabricated vertical drain improvement and incorporates zone-specific improvement depths.

"Constructability verification is a process designed to prevent trial and error during the main construction phase," the consortium said. "We will ensure there are no disruptions to offshore prefabricated vertical drain construction through additional verification and equipment improvements."

Gadeokdo New Airport is a state-led project worth 10.7 trillion won ($7.96 billion) to be built on Gadeokdo in Gangseo-gu, Busan. Priority construction work is set to begin in November, with the main construction phase scheduled to start in the first half of 2027. The government is targeting a 2035 opening.


lucky@heraldcorp.com