Soil and groundwater legislation in Japan – an ASER update

Although there are laws which can oblige polluters to clean up contaminated groundwater, there are still no national laws in Japan requiring a site owner to remediate contaminated land.

Japanese business remains firmly opposed to the introduction of any such mandatory requirements, perhaps fearful of the US Superfund experience. The common practice for local government and private land owners when discovering severe contamination on site has been containment or removal of the contaminated soil for disposal or containment elsewhere. However, Japanese firms are now beginning to quietly engage in more proactive treatment of their contaminated soil, often using techniques perfected in the US and Europe.

The key legislation regarding groundwater contamination is the Water Pollution Control Law. Provisions for the continuous monitoring of groundwater quality were introduced in 1997 by the Environment Agency. These controls include the setting of environmental quality standards (EQS) for specified substances. The law was amended in 1997 to allow prefecture authorities to order polluting companies to clean up contaminated groundwater. Since then, hundreds of clean-up orders have been issued throughout Japan. While there are 26 substances for which groundwater EQS have been set, the key contaminants of concern are TCE and other chlorinated organic pollutants. This year, EQS have been set for boron, fluorine, and nitrate and nitrite.

There are also 25 EQS for soil, but as yet there are no legally binding requirements for clean-up. However, in 1999 the Environment Agency published guidelines urging companies to take action if contamination reaches certain levels. The guidelines prescribe containment and remediation technology options for heavy metals and volatile organic substances in groundwater and soil.

Two levels of criteria are set for recommended clean up of soil. Firstly, there are “trigger levels” for soil contamination. These are reference levels for pollutants also commonly found in nature. These levels function in a similar way to the Dutch Guideline (Intervention T values), serving as a guide to the landowner that there is a problem and that some action is recommended. Trigger levels have been set for only four metals, as specified in the table below.


Trigger Level







Total mercury


Secondly, following intrusive soil investigation, the table at the bottom of the page shows the limits which should trigger action in the form of enhanced containment or remediation.

It should be noted that PCBs, Thiram, Simazine and Thiobencarb are included in the Environment Agency’s classification of metals for the purposes of these standards, although they are clearly not metals in the chemical sense. No VOC criteria for soil remediation are mentioned in the Environmental Agency’s 1999 guideline.

In September 1999, Japan’s Soil Environment Centre, which is a semi-government organisation set up as a centre of knowledge on the soil investigation and remediation issue, announced it had set up a research programme to look at treatment methods for dealing with soil contaminated by oils.

The centre will submit a plan to the Environment Agency in 2000, following pilot clean-up projects. The Soil Environment Centre has proposed using the Dutch Reference and Target values for TPH (total petroleum hydrocarbons) in Japan, although these proposals have not been accepted in any way by the Environment Agency and such standards are not likely in the next two years, due to the agency’s pressing work load on other standards for soil. However, it is estimated that oil contaminated of land represents the single biggest environmental liability for landowners in Japan, and regulatory guidance is likely soon. The centre also proposes setting soil and groundwater EQS for toluene, xylene, and ethylbenzene.

Within this national level framework, local governments are free to implement controls as they see necessary given the level of contamination in their localities. Industrial prefectures near Tokyo are especially progressive in their implementation of controls. Kanagawa Prefecture, for example, requires land owners to carry out an environmental site assessment before the sale of land which may be at risk.


Limit (mg/L)


Limit (mg/L)





total cyanide


alkyl mercury














total mercury







This update is taken from ASER’s new associate publication, Japan Environment Review. For subscription details or more information on Japan Environment Review contact Philip Massey .

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