The plant that was the subject of the investigations used TCE in parts cleaning processes in the past. When the investigations were conducted, the plant was no longer operating and was being used as a warehouse. The Phase I and Phase II Investigations were carried out with the sale of the plant’s site in mind. The results confirmed the presence of soil and groundwater contamination by TCE and other substances. We reported the contamination to the government and engaged in risk communication with nearby residents, and then conducted soil and groundwater remediation (two-phase suction method).

For the Phase I Investigation, we investigated past land use at the site, details of the operations that took place there, the circumstances of chemical and waste management, and other matters. We then planned the Phase II Investigation. For this investigation, we obtained a picture of the soil and groundwater contamination by conducting a soil gas survey, surface soil investigation, boring investigation, and groundwater investigation. Next, we prepared a soil and groundwater remediation plan, held discussions with government and briefings for residents as forms of risk communication, and then executed the remediation work.

Because houses were situated next to the plant, the residents’ briefing was unsuccessful in gaining their understanding and became disorderly. However, over time, we earned their understanding by carefully explaining that contaminated groundwater would no longer flow outside the site after the remediation work was completed and that we would properly manage the contamination until the completion of work.