One of Japan's major newspapers, the Mainichi Newspapers, 16/02/2010 issue reports that total number of the piles driven into the ground of the old gas works at Toyosu, where the TMG is planning to relocate the Tsukiji Market to, reaches as many as 18,000. The figure of 6,000 quoted in the previous entry of this blog has turned out to cover only one of three blocks of the area concerned. The fact was made clear by a citizen group under the information disclosure law.

There are four types of the buried piles: ca 14,000 made of concrete, 17.5 meters long in average; 500 of steel, 34 meters long; some of wood (pine tree), 10 meters long; some of synthetic materials, 16 meters long. They are considered to have been used to stabilize the landfilled ground for facilities of the old gas works.

"Pine-tree piles are not easy to decay. But one cannot say that there is no probabilty that steel ones and others rust away to pass soil contaminants" commented Mr Tatemasa Hirata, who served as chairman of the Expert Panel on the Countermeasure Works for Soil Pollutions of the Proposed New Market Site at Toyosu.

Mr Hirata said also that he was informed of nothing about the piles in those days when he was the chairman. Tokyo explained that there was no need to report him on them since it was a common practice not to eliminate buried things, when improving soil, but to cut off and pull away, only when these were found obstructive.

However, the newspaper articles does not mention other significantly related, already known facts. That is, in addition to salt from sea water penetratable to the landfilled ground, alkali of high degree (pH13) is found in the groundwater seeping out at Toyosu. Who can say that such elements have been not causing electric corrosion to the piles made of steel?

Also, what are the odds that the piles, being some 300 kilometers long in total, do not pierce the impermeable bed which the Tokyo officials insist prevents soil pollution from expanding to groundwater?