The Shadow of Industry Left Underground: Shudo Town's Story of Underground Time (1993)

The Shadow of Industry Left Underground: Shudo Town's Story of Underground Time (1993)

In a nationwide groundwater contamination survey conducted in 1993, tetrachloroethylene was detected in wells in the town of Shuto-cho, Yamaguchi Prefecture, at levels 7,301 times the environmental standard. This concentration was unprecedented in the history of Japanese surveys, and rather than being the result of a sudden accident, it was the result of traces deposited underground over a long period of time by industrial activity during the Showa period (1926-1989) that appeared in the early part of the Heisei period. In the area around Shuto-cho, small and medium-sized metalworking, woodworking, and chemical factories were scattered among farmland, and tetrachloroethylene was widely used as a cleaning solvent in the 1960s and 1960s. The handling of tetrachloroethylene at that time was very lax by today's standards, including outdoor storage and treatment by permeation into the ground, and these practices allowed the solvent to accumulate in the soil over many years.

The geology of Shuto-cho is a combination of valley formations and sand and gravel beds, and the groundwater veins are unevenly distributed, so it is thought that the conditions were such that the contaminants flowed intensively into specific wells. According to data from the Ministry of the Environment, wells in the Shimokuhara area recorded values of approximately 220 milligrams per liter (730 times the standard), and the relationship with nearby business establishments was investigated. 1992 was also a time when the revision of the law and the strengthening of water quality monitoring made the pre-regulation memories left by Showa-era practices visible in numerical form. Since then, drinking water has been discontinued and the water supply has been switched over, and tetrachloroethylene is not detected in the current Iwakuni City Water Quality Annual Report. The case of Shuto-cho was a symbolic event that illustrates the long-term effects of industry on the land and the pr
ocess of time sinking underground and being pushed back into the future.