Exclusive: Two-Thirds of Permeable Paving Blocks in Seoul Found Defective Amid Monsoon Season

[Anchor]

The monsoon season is expected to bring rain across the country throughout this week. When heavy rain falls, the inability of the ground to absorb water can lead to significant damage. To prevent this, the Seoul Metropolitan Government has been installing permeable paving blocks, designed to allow rainwater to drain through. However, it has been revealed that these blocks are largely defective and failing to perform their intended function.

Climate and Environment Correspondent Jang Se-man reports exclusively.

[Reporter]

On city streets during the rain, asphalt surfaces are covered in puddles, while sidewalks paved with blocks remain clear.

This is where permeable blocks, which allow water to pass through, have been installed.

They are designed with numerous microscopic pores that allow rainwater to drain and seep into the soil.

[Jo Si-hyung / Seoul Metropolitan Government Official in charge of permeable blocks: Permeable blocks play a role in preventing urban flooding by absorbing some of the rainwater.]

Videos from manufacturers show a clear difference between permeable blocks that absorb water and regular paving blocks that do not.

But do the blocks installed on actual streets drain water as effectively?

The Seoul Institute conducted a field survey on 30 locations where the blocks had been installed for less than a year.

The test involved placing a bucket on top of the blocks and measuring how quickly the water drained through.

While 10 locations met the installation standard of absorbing at least 0.1mm of water per second, 18 locations showed an absorption rate of only 40 percent of the standard, and the remaining two did not drain water at all.

This means two-thirds of the blocks were defective.

[Park Dae-geun / Senior Research Fellow at The Seoul Institute: The results showed that about two-thirds were either clogged or mostly blocked. We need to recognize the severity of these findings.]

The Seoul Metropolitan Government previously enacted an ordinance in 2015 making the installation of permeable blocks mandatory to reduce rain-related damage.

The city explains that over time, foreign substances like dust and soil can enter and clog the pores of the blocks.

However, as a large number of blocks installed less than a year ago were found to be defective, critics argue that the city must investigate whether substandard products were supplied in the first place.

The Seoul Metropolitan Government has decided to expand its inspection to 1,000 locations for precise measurements.

(Video reporting: Kim Young-hwan, Video editing: Ahn Yeo-jin)

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[Anchor]

We are now joined by reporter Jang Se-man, who covered this story, for more details.

Q. How many permeable blocks are installed in Seoul?

[Reporter Jang Se-man: I have brought both a permeable block and a regular block here. As you can see, the regular block has a smooth surface, while the permeable block is textured with many gaps. As mentioned earlier, the Seoul Metropolitan Government made the installation of these blocks mandatory starting in 2015. However, they currently account for only about 15 percent of all sidewalks in the city. Permeable blocks are about 10 to 20 percent more expensive than regular ones. The city explains that installation is slow because they are only replaced when old blocks need to be changed, rather than tearing up perfectly fine sidewalks to replace them.]

Q. Was the possibility of clogging not anticipated?

[Reporter Jang Se-man: They were well aware of that possibility. In fact, current regulations require the performance of these blocks to be inspected once every two years. However, this has not been carried out properly. Because the installation rate was low and there was no established testing method to measure the blocks' performance, it was difficult to enforce. Recently, The Seoul Institute developed a testing method, making this the first year that a proper inspection has been conducted. The city explained that they expected some clogging and had originally planned to remove debris from the blocks using high-pressure cleaning equipment.]

Q. What are the countermeasures for clogged permeable blocks?

[Reporter Jang Se-man: Even normal permeable blocks can get clogged with debris after long-term use. Performance maintenance and management are crucial. The equipment you see now is used to spray high-pressure water to remove debris, but there are currently only four such machines in Seoul. Expanding the use of this high-pressure cleaning equipment and increasing the frequency of cleaning will be important to restore the performance of these blocks. Furthermore, a broader investigation is needed to determine if there were any issues with the issuance of test reports during the supply process and to assess the overall condition of other permeable blocks.]
※ Please note: This article was translated by AI and may contain errors.