A massive sinkhole near Tokyo that swallowed a truck and its driver a week ago, and has filled with sewage and debris, highlights the risk posed by Japan’s ageing pipes.
Emergency workers have been striving in vain to reach the 74-year-old man, who rescuers have had no contact with for a week, and who was likely buried under sediment and sewage water in the sinkhole in the city of Yashio.
Officials say corroded sewerage pipes created the sinkhole that is now nearly the size of an Olympic swimming pool.
Cranes have been mobilised and a 30m slope built to locate and reach the driver, with a second slope under construction, but progress has been slow and dangerous.
Koichi Yamamoto, an official with Yashio’s fire department, told AFP on Tuesday that rescue efforts had been suspended.
When the hole suddenly opened up in Yashio, in the region of Saitama near Tokyo, during the morning rush hour on Tuesday last week, it at first looked like just one of thousands of sinkholes reported annually across Japan.
Their occurence is trending upwards, topping 10,000 in fiscal 2022, with many of the sinkholes sewage-related in urban areas, a land ministry probe shows.
Initially the hole was around 5m in diameter, then a much larger cavity opened nearby and the two holes merged.
To reduce the volume of sewage, locals were urged to “use as little water as possible” for three hours on Tuesday afternoon.
The week-long sinkhole saga was a reminder of the insidious corrosion gnawing at Japan’s ageing water and sewerage pipes, Shinya Inazumi, a professor of geotechnical engineering at Shibaura Institute of Technology, told AFP.
“Many sewerage pipes in Japan have already outlived their service life (of 50 years) so pipes anywhere else could break due to ageing,” Inazumi said.
In just over 15 years, 40% of Japan’s sewerage pipes will have exceeded their lifespan, according to an estimate from the land ministry.
In Yashio, local authorities attributed the initial chasm to rusty, punctured sewerage pipes that absorbed the surrounding soil, creating a hollow under the ground.
Extreme weather events such as intense rain can also exacerbate this kind of infrastructure failure, Inazumi said.
“Rainfall these days can be extremely heavy and localised, which means a great amount of water seeps underground,” the professor said. — AFP
