Japan: 240,000t of unapproved steel slag have been found buried at a US$66m residential development in Sodegaura, Chiba Prefecture, according to local press. The slag lacks the approval of the landowner contravening the Land Readjustment Act. The Land, Infrastructure, Transport and Tourism Ministry has started to investigate.
The Nippon Steel & Sumitomo Metal Corporation's Kimitsu works produced the slag before selling it to the developers. Research by the Mainichi newspaper suggests that the developers used the slag for ground improvement in 2012 before approval was obtained affecting the finances of the project.
Due to the swelling of slag when it absorbs water, if the slag-to-soil ratio surpasses 30%, users should to test in advance how much the mixture will expand. Steel slag is treated as industrial waste if it is not recyclable. Disposal of such slag costs US$170 – 340/t.
