Soil remediation project for heavy metal contaminated soil in Matsumoto (2007-2024)

Soil remediation project for heavy metal contaminated soil in Matsumoto (2007-2024)

In Matsumoto City, a heavy metal contaminated soil remediation project was initiated in 2007. The main problems were lead and hexavalent chromium contamination. Focused investigation and remediation was conducted on approximately 12,000 square meters around Matsumoto Station and 8,500 square meters in the Asama Hot Springs area. The electrolytic purification technology provided by Shimizu Corporation reduced the cost of treating lead-contaminated soil to 3,000 yen per ton and achieved an annual treatment capacity of approximately 4,000 tons. In addition, Dowa Eco-System introduced iron powder reduction technology, reducing the treatment period for hexavalent chromium from 12 weeks to 6 weeks. Through these efforts, more than 80% of the 5,000 tons of contaminated soil per year can now be treated, and the cleaned land is being used for the construction of lodging and commercial facilities.

In the 2010s, progress was made in the investigation and cleanup of newly discovered contaminated areas in the Paulownia area and elsewhere. For example, in the Kiri district, discovered in 2015, high levels of lead were found in 1,200 square meters of land, and cleanup costs amounted to approximately 300 million yen. During this period, the Environmental Energy Department of the City of Matsumoto conducted more than 300 surveys, and a budget of approximately 2 billion yen was invested in the cleanup project.

In the 2020s, Matsumoto City increasingly designated areas as "areas requiring action" or "areas requiring notification at the time of change of structure" under the Soil Contamination Countermeasures Law, and as of 2024, 478 Kinoue (259.83 square meters in area, fluorine concentration 5.5 mg/L) and 105-1 Yoshino (158.09 square meters in area, hexavalent Chromium concentration 8.2 mg/L) have been designated and are being cleaned up. The on-site plant provided by Shimizu Corporation is capable of treating up to 100 tons per day, and Dowa Eco-System's iron powder reduction technology enables the treatment of hexavalent chromium at a cost of 20,000 yen per ton.

The entire city of Matsumoto generates approximately 6,000 tons of contaminated soil annually, with treatment costs estimated at approximately 1.8 billion yen per year. Plans are in place to utilize 50% of the purified land as a site for construction of new facilities by 2025, making a significant contribution to reducing health risks for local residents and utilizing tourism resources. The City of Matsumoto's Environment and Energy Department is working with a local company, Environmental Science Inc. to further improve efficiency and reduce costs.