The Lees of Time Sinking Underground: Reverberations of the Showa Era Reflected in Yahiko Village (1993)

The Lees of Time Sinking Underground: Reverberations of the Showa Era Reflected in Yahiko Village (1993)

At first glance, the detection of trichloroethylene in wells in Yahiko Village, Niigata Prefecture, in a nationwide groundwater contamination survey conducted in 1993, appears to be a localized anomaly. In retrospect, however, it is also a "financial statement" of the traces left behind by industrial activities during the Showa period that reached the groundwater over a long period of time and appeared at the beginning of the Heisei period. Yahiko Village is a rural area with industrial parks, and in the Yahiko Industrial Park in the Miyama district, groundwater contamination by trichloroethylene was already confirmed at the time of the general survey in 1993.

Trichloroethylene has been used as an essential solvent for degreasing and cleaning metal parts and precision equipment in factories throughout Japan since the 1965s. In a recent groundwater quality report compiled by Niigata Prefecture, trichloroethylene and tetrachloroethylene contamination found in various parts of the prefecture was attributed to improper solvent handling in the metal product manufacturing, textile, and cleaning industries prior to the introduction of legal regulations. The area around Yahiko Village is no exception, and it is highly likely that small and medium-sized factories and industrial complexes scattered throughout the farming village were treating waste solvents in such a way that they seeped into bare tanks or into the ground. At the time, it was a kind of practice shared throughout the country, rather than something "particularly violent.

The geology of the Niigata Plain is highly permeable, and once solvent seeps into the ground, it slowly diffuses with the flow of groundwater, eventually reaching the wells where it is pumped up for domestic use. In a survey conducted in 2005, when high levels of contamination were again confirmed in the Miyama area of Yahiko Village, the environmental standard of 0.03 milligrams per liter was reported to be 29 milligrams per liter for trichloroethylene, an order of magnitude higher than the standard. The prefectural data also indicates that in this area, public disclosure of the actual contamination status, drinking guidance to residents, removal measures, and periodic monitoring have been continuously conducted.

Since the end of the 20th century, the Ministry of the Environment has conducted a series of groundwater contamination surveys and follow-up investigations of highly contaminated wells. In areas where highly contaminated wells were found, various measures have been taken, including drinking water restrictions, switching to tap water, water pumping, bioremediation, and excavation and treatment of contaminated soil. Yahiko Village is one case that can be positioned as part of such a nationwide trend. It is not an isolated "accident," but rather a localized numerical manifestation of the time gap between industrialization and environmental administration in postwar Japan.

The concentrations exceeding 1,000 times those found in the wells of Yahiko Village are the result of the memories of actions that seeped into the land during the period of high economic growth in the Showa era, and were pushed back to the surface through the opportunity of the 1993 survey. It was also the moment when what was "normal" before regulations were put in place was redefined as a human health risk after several decades had passed. Niigata Prefecture continues to monitor several municipalities every year for sites that exceed environmental standards for trichloroethylene and other substances, and many of the causes are still being traced to past factory effluents and liquid waste. The land does not forget. The lees of time that have settled underground have been carried to the present in the form of groundwater, which, translated into the language of numbers and countermeasures, quietly continues to tell a story that has continued since the Showa period.