toyosu contaminated model
blue area: over 0.001 mg/l(detected)
red area: over 0.01 mg/l(environmental standard)
Between 1956 and 1976, Tokyo Gas Co. operated a plant to manufacture household gas out of coal at the site of the planned new fish market.
The plant stored coal in the site and produced harmful chemicals such as benzene as waste.
The Tokyo government discovered heavy soil contamination in 2008. To date, it has spent more than $500 million to clean up the site, which has included the removal of two meters of topsoil and selective excavation of highly contaminated regions down to 6.5 meters. The entire area has been surrounded by sheet pile walls to contain the groundwater contamination, and a pump-and-treat system is in operation along with continual monitoring. However, contrary to the original plans, the fish and vegetable market basement floors have been found to be permeable and there have been incidents of benzene contaminated groundwater and vapor intrusion into all structures.