(1) Description of the law

In addition to complying with the effluent standards defined by laws and regulations for water discharged from factories and plants, it is also important for them to implement soil management practices for their factory site. It is imperative for the management to implement countermeasures for preventing soil and groundwater contamination caused by harmful substances leaked to or soaked into the factory ground.
In the past, old factory site developed into a common area or a residential area turned out to be contaminated with heavy metals or organic compounds such as trichloroethylene, which posed danger to the residents.
To prevent such problems, the Soil Contamination Countermeasures Act was established, which went into effect on February 15, 2003. The purpose of this law is to mandate the plants and factories involving the use of harmful substances in their processes including surface treatments to perform a pollution survey when they sell the business or reuse the land for new construction. If the soil is contaminated, the land is subject to soil purification.
The harmful substances designated by this law are as follows:

Category I Specified Toxic Substances

11 types of volatile organic compounds (such as Trichloroethylene)

Category II Specified Toxic Substances

Nine types of heavy metals including lead and its compounds

Category III Specified Toxic Substances

Five types of agrichemical substances including Simazine

(2) Standards for heavy metals

The soil elution amount and content are the two reference values used for evaluating the degree of soil contamination caused by heavy metals. [Table 1] shows these reference values.

[Table 1] Reference values of soil elution amount and its content

(1) Soil Leachate Standard

The Soil Leachate Standard was established in consideration of health risks caused by ingesting groundwater containing harmful heavy metals eluted into it through rainwater and waterways. The concentration is calculated by using a soil sample of certain weight and measuring the amount of harmful substances dissolved into pure water.

(2) Soil Concentration Standard

The Soil Concentration Standard was established in consideration of health risks caused by a high concentration of harmful substances in the soil containing heavy metals when people inhale the soil particles by accident or the soil contacts the skin after it had spread into atmosphere.