Cleanup of Soil and Groundwater Contaminations
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In fiscal 2007, OMRON's survey identified volatile organochlorine compounds that exceeded environmental standards, found in the soil and groundwater on the grounds of OMRON's Kusatsu Factory. OMRON estimates that this was primarily caused by the leakage of a chemical substance previously used for cleaning parts, which was discontinued 24 years ago. Hazardous substances polluting soil and groundwater that exceeded environmental standards were also detected at the Okayama Factory. This problem is thought to be mainly caused by waste present at the waste disposal facility located on the grounds before the Okayama Factory commenced operation.
As a company committed to living up to its CSR, OMRON takes these findings very seriously, and thus is promoting cleanup measures in order to ensure maximum safety and security for inhabitants in neighboring areas, at the earliest possible time. （Photo:Iron powder injection method for cleanup at Kusatsu Factory）
Kusatsu Factory
Cleanup measures involving injection
wells and bulkheads
Volatile organochlorine compounds detected at the Kusatsu Factory in Shiga Prefecture included: trichloroethylene(Note 1) with a peak level 1. 6 times the standard maximum value and cis-1, 2-Dichloroethylene(Note 2) with a peak level 16.3 times the standard maximum value from soil. Also from groundwater, cis-1, 2-Dichloroethylene with a peak level 17 times the standard maximum value was detected. The Kusatsu Factory had used trichloroethylene for cleaning pressed parts until 1983. This substance may have leaked out into the soil for some reason, where it remained and decomposed.
As an immediately effective remedy, OMRON constructed approximately 50 wells inside the boundary of the premises to decompose cis-1, 2-Dichloroethylene and purify groundwater flowing out of the site. OMRON also surrounded the polluted soil with bulkhead to prevent outflow of contaminated groundwater, while at the same time chemically reducing the contaminated soil inside the bulkhead using iron powder. OMRON is continuing to monitor the situation, and aims to complete this cleanup process by 2010.
- Note1: Trichloroethylene：
- Trichloroethylene was widely used as a cleaning agent due to its high degreasing properties until the 1980s. In 1989 in Japan, this substance was designated as a Class II specified chemical substance that has the potential to cause damage to human health if continuously exposed, and a standard value has been specified by the Environment Basic Law.
- Note2: cis-1,2-Dichloroethylene：
- cis-1,2-Dichloroethylene is a decomposition product of trichloroethylene. As with trichloroethylene, a standard value has been specified by the Environment Basic Law for this substance as well.
Hazardous Substances Detected at Kusatsu Factory and Cleanup Measures
| Item | Sur- veyed wells |
Wells where surveyed values exceed standards |
Peak level (mg/l) |
Standard value (mg/l) |
Max. pollution factor (times) |
Cleanup measures |
|
|---|---|---|---|---|---|---|---|
| Ground- water |
cis-1,2- Dichloro- ethylene |
37 | 9 | 0.68 | 0.04 | 17 |
|
| Soil | Trichloro- ethylene |
21 | 2 | 0.049 | 0.03 | 1.6 |
|
| cis-1,2- Dichloro- ethylene |
21 | 5 | 0.65 | 0.04 | 16.3 | ||
Okayama Factory
Implementing voluntary cleanup
measures to make extra-sure
Well construction for
pumping contaminated
water at Okayama Factory
At the Okayama Factory, lead, fluorine, arsenic, cyanogen, PCB and boron, designated as hazardous substances by the Soil Contamination Countermeasures Law, were detected from soil, perched water(Note 3) and groundwater within the factory grounds. Except for natural substances such as arsenic, fluorine and boron, the findings of all other substances are thought to be caused by waste that had been buried in landfill before the start of the factory's operation.
In the neighborhood of the factory, groundwater is not used as drinking water and no specified chemical substances have been detected. Also, as pollution levels are low, the Okayama municipal government took the position that this pollution would not impact life in the neighboring area. Even so, OMRON is voluntarily implementing cleanup measures. These include purification of groundwater and perched water using a water treatment system and wells for pumping up polluted water, as well as soil replacement for contaminated areas.
- Note3: Perched water：
- Perched water is a separate body of groundwater about 2m below the ground surface, lying above the main groundwater separated by an impermeable clay or rock layer.
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