Photo/IllutrationThe planned site of the new Toyosu market in Tokyo’s Koto Ward, foreground (Asahi Shimbun file photo)

New additional countermeasures against soil contamination at the Toyosu market site will cost up to 12 billion yen ($107.7 million), but the head of an expert panel admitted that they may not immediately lower high benzene levels.

The measures were discussed at the panel meeting on May 18, which is looking into safety issues at the site for the relocation of the capital's Tsukiji fish market to the Toyosu district of Koto Ward.

They include maintenance and operation costs for 65 years in the event the planned relocation, which was delayed from November by Tokyo Governor Yuriko Koike over safety concerns at the Toyosu site, proceeds.

Benzene at levels up to 100 times higher than environmental standard were also found in groundwater samples from the Toyosu site in April after the previous survey in March detected the same level.

“It will take time to lower the level of benzene (even after additional measures are to be taken),” said panel head Tatemasa Hirata, director of the Wakayama Study Center of the Open University of Japan.

Hirata’s remark provoked a fierce backlash from traders who attended the panel meeting, saying, “Relocation of the Tsukiji market to the Toyosu site is unacceptable if (the Tokyo metropolitan government) cannot guarantee rendering the site as harmless.”

The traders’ anger brought the panel's discussion to an end for the day.

The proposed new measures include plans to cover contaminated soil with concrete as well as to strengthen drain pumps.

Outlays for soil contamination countermeasures have already cost about 86 billion yen. If the relocation of the aging Tsukiji market to the new site in Toyosu proceeds, 6 billion yen to 12 billion yen will be added to the expense.

Since Koike wants to assure the safety of the Toyosu site, she plans to decide on the relocation in light of reports including additional measures compiled by the expert panel.

To prevent vaporized hazardous substances from flowing into the market at ground level, the proposed contamination measures include plans to

fill the underground area with concrete or special sheets and to install ventilating apparatus, according to materials released at the meeting.

In addition, drain pumps will be added with the aim of lowering the concentrated levels of harmful substances.

The Tokyo metropolitan government has estimated the construction costs of filling underneath the Toyosu market site with concrete at around 3.5 billion to 4.5 billion yen while covering it with protective sheets will total around 7 billion to 8 billion yen.

Maintenance and operation costs for 65 years, which is the estimated useful life of the main Toyosu market building, will cost about 2.5 billion to 4 billion yen.

The panel has reviewed contamination countermeasures when it was discovered that soil replacement and land elevation work had not been done under major facilities at the Toyosu market and when the concentration of hazardous substances in groundwater surpassed environmental standards.

The expert panel planned to compile reports in its next meeting, but is considering holding another meeting prior to that.

If there is a delay in writing the reports, that could affect the timing of Koike’s decision on whether to proceed with the Tsukiji market’s relocation.