Ulsan City Successfully Completes Nationwide First Underwater Full-Open Condition Sewer Pipeline Dredging

1995 Installation of Jangsaengpo Sea-Crossing Subsea Pipeline

New Construction Plan Expected to Save Over 30 Billion KRW in Project Costs

Ulsan City announced on the 26th that it has succeeded in dredging a fully filled (man-gwan) state sewer pipe for the first time in the nation.

The sewer pipe dredged this time is a total of 31 km long, transporting sewage generated in the Nam-gu area to the Yongyeon Water Quality Improvement Plant, and was installed in 1995.

Among them, about a 200m section is buried 14m deep under the Jangsaengpo sea, making it impossible to monitor internal damage or leakage for about 30 years since its installation.

After investigations using the latest technologies such as ultrasound, underwater exploration (sonar), and electrical leakage detection, Ulsan City confirmed that about 60-80% of sediment had accumulated in one of the double-line pipes.

However, since sewage was always flowing in a fully filled state, dredging by conventional methods was difficult, and if construction was impossible, a plan was in place to consider additional pipe installation with a budget of about 30 billion KRW.

Recently, a method enabling dredging without diverting water was introduced using a separation-discharge dredging technique developed by a domestic company. Accordingly, Ulsan City applied this technology, started construction in August, and completed it on November 14, four months later.

With this construction, Ulsan City achieved the nation's first success in dredging a fully filled underwater sewer pipe and expects to save more than 30 billion KRW in budget that would have been spent on new underwater pipe installation and maintenance.

An official from Ulsan City said, “With the success of the Jangsaengpo underwater sewer pipe dredging project, the flow of sewage pipes in the Nam-gu area will become smoother,” adding, “Based on this achievement, we plan to further enhance the efficiency of sewer pipe management.”

Ulsan City Hall.