Existing Sewer Evaluation Results and Rehabilitation Strategies: The City of Seoul, Korea

In my last 3 months here in Seoul, I realise that getting the wastewater to the treatment plant can be a real challenge. In fact, venting the sewer gas can be a real problem. The infrastructure is something to consider as we "green" the water systems in densely populated, older cities.

Abstract

A sewer evaluation study was conducted for the eight basins in the City of Seoul. The results indicated that the sewer system has a problem at every 5 m. This condition increases the amount of inflow and infiltration resulting in poor operation of the publicly owned treatment works (POTWs) which are owned and operated by the City.

The study also identified that the following five defects as responsible for more than 87% of the problems: joint defects (27.5%), protruding lateral (21%), service connection defects (14.5%), sand/gravel debris (13.0%), and structural cracking (11.0%). In addition to the structural and hydraulic degradation, these problems are the main causes for an average inflow and infiltration of 109.4 m3 hectare−1 day−1.

To fix these problems, use of trenchless rehabilitation technologies are recommended considering the congested conditions of Seoul. It is estimated that an average of $95 800 per hectare is required for rehabilitation. For the entire Seoul system covering 605.9 km2, a total rehabilitation cost is estimated of approximately 5.8 billion dollars.

In addition, to increase the effectiveness of rehabilitation, recommendations are made including preparation of more detailed rehabilitation guidelines, specifying ways of service line connection, use of sanitary catch basin and tight construction supervision.

Keywords: Sewer evaluation, rehabilitation strategy,  infiltration and inflow, Seoul

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Taxonomy

• Water Reuse & Recycling
• Wastewater Treatment
• Wastewater Collection
• Industrial Water Reuse
• Integrated Urban Water Management
• Reuse
• Urban Water Infrastructure
• Institutional Development & Water Governance
• Waste, wastewater, air, chemical engineering

2 Comments

1. John, The sewerage gas is actually a small mention in the article, so it probably shouldn't have been in my headline.
   
   There are (unsurprisingly) compound issues here in Seoul. My neighbor downstairs is a civil engineer and he and I were talking about how people throw welcome mats over the sewer grates along the curbs. He explained to me that the sewers are too old and complex to easily solve gases, sewer leaks, and cleaning. The mats seal the gasses into the sewer - and as you can imagine cause problems during the summer rainy season if they aren't removed.

    

   Those who have visited Seoul are frequently hit by a wall of sewer smell as you round a corner or descend into a subway tunnel. A citizen-journalist wrote an op-ed article last year. https://medium.com/travel-inside-and-out/today-in-seoul-42-eeuuwww-whats-that-smell-1f1f28401664
   
   I'm not as bothered by the Seoul sewer smell in contrast to the urine smell in downtown Los Angeles. It's almost more comforting to know the difference between someone urinating on a building versus an old sewer trying to carry the wastewater towards a treatment plant.

2. Hi Shauna, nice article, I am in Manila another old SEA City, with all the same problems and some. You mentioned venting the sewer gas in your heading, but no mention elsewhere. What have been your main concerns in this area and any remedial actions recommended. Thanks John