Question: “Why on earth would anyone do this?”
Answer:”I guess it’s better than sitting unprotected in barrels on the school grounds for years until the national govt got around to classifying the sludge as radioactive waste. And burying it on school grounds has a precedent in Fukushima that everyone seems to think is OK. Why would Yokohama be treated any differently? (Please read in sarcastic tone of voice.)
Special credits to Jack Hiro and Beverly Findley-Kaneko for this information and comments.