[Anchor]
We previously reported that permeable paving blocks installed to prevent flood damage are failing to perform their intended function. We decided to test the blocks directly to determine whether the issues stem from wear and tear over time or if they were defective from the start.
Reporter Jang Se-man has the details.
[Reporter]
At Banpo Hangang Park in Seoul, where permeable block installation work was completed last month.
Iron rods are inserted into the gaps between the ground to pry out the blocks.
We collected permeable blocks from three recently completed construction sites, including this one, and brought them to a testing institution.
To be selected as supply-grade permeable blocks, products must pass tests by a specialized institution and submit their test reports to local governments.
The blocks collected here are also products chosen through that process, and we will test them using the exact same methods as their original test reports.
The test results showed that all samples from the three locations fell short of the passing criteria.
At a site where a drainage performance rating of Grade 2 or higher was required for supply, the blocks received a Grade 3 and an unrated designation. At sites where Grade 3 or higher was required, the results were Grade 4 or "unratable," indicating virtually no drainage.
Permeable blocks work by creating countless microscopic pores inside to allow water to drain. Over long periods of use, foreign substances like sand or dust can clog these pores.
However, experts note that since these samples were installed anywhere from one to four months ago at most, contamination after installation is unlikely.
[Park Ji-won / Democratic Party Representative: Because we found and tested blocks from the most recently constructed sites, we have no choice but to conclude that they were defective products from the very beginning, meaning such defective products are likely widespread.]
Within the industry, rumors openly circulate that manufacturers secure test reports with normal products, only to use low-quality, substandard items during actual construction.
Critics point out that post-construction verification to ensure the blocks used match those that passed the tests is severely lacking.
[Choi Kyung-young / President of the Low Impact Development Association (Adjunct Professor at Seoul National University): It is necessary to immediately conduct on-site verification alongside completion inspections to check whether the permeable blocks actually exhibit drainage performance once installed on-site.]
It has been about a decade since permeable blocks were introduced in Seoul, and they now account for 15% of all sidewalk blocks. A thorough investigation is urgently needed to evaluate their current performance and understand why these issues have gone unchecked.
(Video Editing: Lee Sang-min, VJ: Shin So-young, Oh Se-kwan)
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