The news headlines at various media outlets say "ashes that contain up to 100,000 becquerels/kg of radioactive cesium", but if you read the news carefully, as long as there are "countermeasures" to prevent the leakage of radioactive cesium into the surrounding environment, the Ministry is prepared to allow the ashes with any amount of radioactive materials to be buried in regular waste final disposal facilities.
From NHK News (8/28/2011):
原発事故で放射性物質が付着したがれきや一般ごみを燃やした灰について、環境省は、含まれる放射性セシウムが１キログラム当たり８０００ベクレルを超えるものも、地下水への流出を防ぐ対策をしたうえで、埋め立てができるとする方針をまとめました。
Regarding the ashes after burning the disaster debris and regular household garbage contaminated with radioactive materials, the Ministry of the Environment has decided on a policy that will allow the burial of ashes that exceed 8,000 becquerels/kg of radioactive cesium, as long as there are countermeasures in place to prevent the leakage into the ground water.
これは、２７日開かれた環境省の専門家による会合で示されたものです。放射性物質が付着したがれきの処理について、環境省はこれまで、燃やした灰に含まれる放射性セシウムが１キログラム当たり８０００ベクレル以下であれば埋め立てを認める方針を示していましたが、より濃度が高い灰については一時保管するよう求め、処理方法の検討を続けてきました。
The new policy was revealed during the meeting of experts affiliated with the Ministry of the Environment on August 27. So far, the Ministry's policy has been to allow the ashes with 8,000 becquerels/kg of radioactive cesium and below to be buried, but require the ashes that exceed that level to be stored temporarily while the Ministry decides on the disposal method.
新たな方針では、放射性セシウムが８０００ベクレルを超え１０万ベクレル以下の場合は、放射性セシウムが地下水に流れ出ないよう、灰をセメントで固めたりコンクリートの容器に入れたりしたうえで埋め立てられるとしています。また、１０万ベクレルを超える灰はさらなる対策として屋根やコンクリートの囲いがある処分場に埋め立てるとしています。
Under the new policy, if radioactive cesium in the ashes exceeds 8,000 becquerels/kg but does not exceed 100,000 becquerels/kg, the ashes are allowed to be buried after they are bound with cement or put in a concrete container. If radioactive cesium exceeds 100,000 becquerels, then the ashes should be buried in the disposal facilities with a roof and/or with the concrete shield.
一方、これまでに関東や東北地方で一般ごみを燃やした灰からも、１キログラム当たり８０００ベクレルを超える放射性セシウムが検出されるケースが相次いでいましたが、環境省は一般ごみの焼却灰についてもがれきの処理方針に沿って埋め立てを認めることを決めました。これによって、各自治体は一時保管していた焼却灰の埋め立てを進めることになりますが、処分場周辺の住民の理解を得ることが課題となることも予想されます。
Radioactive cesium exceeding 8,000 becquerels/kg has been detected from the ashes from burning the regular household garbage in Kanto and Tohoku regions. The Ministry of the Environment has decided to apply the same rule as the disaster debris and allow the ashes to be buried. The municipalities will be able to bury the ashes that they have stored temporarily, but it may be difficult to obtain consent from the residents living near the disposal facilities.
The number "100,000 becquerels/kg" is significant in a sense, as the highest level of radioactive cesium found from ashes after burning the household garbage is 95,300 becquerels/kg in Fukushima Prefecture (link in Japanese). The number is high enough to clear the Fukushima garbage ashes, and it is probably high enough to clear garbage ashes from anywhere else.
Besides, as the NHK article states, even if it exceeds 100,000 becquerels/kg, all they need to do is to bury it in a disposal site with a roof or the concrete shield.
This new policy is to be applied to ashes from disaster debris and regular garbage that are radioactive. It's not mentioned in the article but the ashes and slag from the radioactive sewage sludge will be likely to be disposed under the same policy - i.e. burn and bury. (And remember the "mix and match" scheme.)
In the meantime, some garbage incinerators and sludge incinerators at waste processing plants and sewage treatment plants in cities in Kanto have become so radioactive that they have to be shut down. (More later.)
The entire country is to become the nuclear waste disposal site, because of one wrecked nuclear power plant. Talk about socializing the cost.