Although Dutch standards shall be-used in the assessment of soil and groundwater contamination, U.S. EPA Region 9 Preliminary Remedial Goals (PRG5) and Australian Oil Industry Environmental Working Group (AOIEWG) Guidelines on the Management of Petroleum Impacted Land screening levels may apply when contaminant levels exceeded the-Dutch Intervention Values.
　　
　　
　　Analysis requirements and appropriate screening levels for various land uses are described in SLA’s ESA Guideline.　The guidelines will address additional analytes in excess of those listed on the Dutch standards, such as explosives, radioactive wastes and asbestos from ammunition dumps and shooting ranges, and dioxins, furans and faecal coliform from sewage treatment plants.
　　
　　
　　Appropriate Tier 1 Risk-Based Screening Levels may be selected for further results interpretation or Tier 2 Human Health Risk Assessment may be conducted to verify potential risks. This allows a more cost-effective contamination management that calls for remediation only when necessary.
　　
　　
　　If the Dutch Intervention Values (DIVs) and ready for use risk-based screening levels are not suitable for the site, then a risk assessment will be required under SLA’s ESA guideline.　The risk assessment may be conducted using internationally accepted methods and models such as U.S. EPA or ASTM risk assessment approaches, or the Johnson and Ettinger (1991) model or equivalent.　By conducting a comprehensive risk assessment, the health risk of the potential receptors can be quantified and the required cleanup levels can be determine in order to identify the necessary remediation process and techniques.　The remediated sites should be certified by qualified consultants and the risk based contamination levels should also be approved by the relevant authorities.
　　
　　
　　Conclusion
　　
　　The regulations on environmental site assessment in Singapore have developed over time.　From the experience in Singapore, land contamination can be controlled by simple implementation of land use zoning in the absence of an established site assessment and remediation guideline, to segregate the pollutive and non-pollutive types of land use developments.　As the economic development progressed, rezoning of land is required resulting in the need to establish a more comprehensive and specific guideline to protect the land and to safeguard the health of the general public.

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