It is a part of Tokyo bay, incinerated ash is used to fill the sea.
Yokohama city government was supposed to filter the water when it overflows from inside of the site to Tokyo bay with zeolite.
However, they quit using it last November. Yokohama city councilor, who found this out assumes Yokohama city is trying to hide the contamination level because if they use zeolite, they can measure how much it is contaminated. They have already deposited incinerator fly ash to the sea, which is the most contaminated and the cesium contained in incinerator fly ash is very water solubility.
Last June, the maximum radiation level of fly ash was 2,400 Bq/Kg.
However, the zeolite was contaminated as 5,000 Bq/Kg though it was used only for 26 days.
There were 5,500 Kg of zeolite to filter, so the total cesium amount was 5,000 Bq/Kg×5,500Kg=27,500,000Bq.
It means, it would have filtered 100 million Bq per day.
They stopped using it since 11/1/2011, about 130,000,000 Bq of cesium has already leaked to Tokyo bay.