Damage State of Wastewater Treatment Facilities in Kumamoto Following 2016 Earthquakes

1. Outline of Kumamoto Earthquakes

On April 14th at 21:26, a magnitude-6.5 earthquake struck the southern Japanese island of Kyushu with the epicenter located in Kumamoto Prefecture. 28 hours later, on April 16th at 1:25, another powerful magnitude-7.3 earthquake shook the same area.

Below: Location of Kumamoto earthquakes

2. Damage State of Wastewater Treatment Facilities

(1) Wastewater Treatment Plants (as of May 10th, 2016)

  • The total number of damages wastewater treatment plants is 13 (12 in Kumamoto Prefecture and 1 in Oita Prefecture).
  • All plants, including the ones that suffered damages, have maintained their normal operation and treatment function.
  • There were 8 damaged portions in the sewer network caused by breakage or blockage however these are now being repaired and do not affect the network function.

  • (2) Wastewater Treatment Facilities in Rural Areas (as of April 27th, 2016)

  • The survey of 4 facilities in Kumamoto indicated that, although subsidence of the land surrounding the plants and cracks in concrete buildings were observed, their function is now maintained and they are operating normally.
  • The sewer network of Kumamoto is partially damaged and causes wastewater overflow in some areas.
  • (3) Sludge/Night Soil Treatment Plants (as of April 25th, 2016)

  • The survey of 5 plants in Kumamoto indicated that 4 of them were damaged. In 1 of them located near the epicenter, the supply pipes from a well were damaged and the operation was stopped. They have since been repaired and normal service operation has resumed. The 3 other plants work properly, although there are cracks in the concrete structure of water tanks and pipe leakage.
  • (4) Johkasou

  • Following the earthquakes, the municipalities in Kumamoto Prefecture conducted surveys to get a clear understanding of the damage situation. As of May 9th, it has been found that a total of 100 facilities were damaged due to different causes, including soil liquefaction. However, it is from now on that the damage situation will be really understood.
  • (5) Others

  • Countermeasures for Human Waste/Night Soil
  • By May 14th, 306 temporary toilets (259 in Mashiki Town, 40 in Minami Aso Village and 7 in Aso City) have been installed under the support of the Central Government. Temporary toilets have also been put voluntarily in convenience stores and supermarkets. In addition, 631 temporary toilets (as of May 18th) have been installed by the prefecture and the municipalities.
    For the collection of human waste, the Kumamoto Prefectural Government and local organizations have kept regular contacts to ensure the continuity of the collection service.

  • Sanitary Conditions
  • 28 people have been infected with Norovirus at a shelter gathering about 500 evacuees in Minamiaso, Kumamoto Prefecture. Sanitary conditions are likely to have deteriorated due to water outage. As a result, the use of 5 out of 9 temporary toilets has been interrupted. (News report, April 23th)

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