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Advisory Council on the Environment

Kai Tak Airport North Apron Decommissioning

 

(ACE-EIA Paper 9/2002)
For discussion

Report on the Final Soil Quality of the Previously Contaminated Areas

Introduction

1. The EIA report for "Kai Tak Airport North Apron Decommissioning" was endorsed by the ACE at its meeting on 31 August 1998 with conditions. One of the conditions is that the project proponent, Territory Development Department, should submit a report on the final quality of the previously contaminated areas upon the completion of the remediation process before starting the proposed housing developments. This was subsequently translated into relevant condition in the Environmental Permit (EP) issued on 23 September 1998 (see paragraph 4 below).

Purpose

2. This paper summarizes the conclusions of the final soil quality report on the previously contaminated areas at Kai Tak north apron area.

Advice Sought

3. As piling work for the first housing development at Areas 1A and 1B in South East Kowloon Development (see Annex A) is targeted to commence in July 2002, Members' views are sought on the conclusions of the final soil quality report prior to housing construction.

Relevant EP Condition

4. The relevant condition in the Environmental Permit EP-006/1998 is: -

"2.8 On completion of the decontamination works and before starting the proposed housing development at the project area, the Permit Holder shall submit the final soil quality report of the previously contaminated areas to the EIA Sub-committee of the Advisory Council on the Environment for inspection. The Permit Holder shall make the results of the final soil quality report available to the public as specified by the Director."

Description of Remediation Process

5. In Hotpsot B (see Annex A), Soil Vapour Extraction (SVE) and Air Sparging (AS) were operated in phases from March 2000 to June 2001. Subsequent to this pre-treatment operation, the remaining heavily contaminated areas in Hotspot B were excavated and treated by biopiling. For the other contaminated hotspots (see Annex A), excavation and biopiling of contaminated soil were undertaken as specified in the approved EIA report. The total volume of contaminated soil treated by SVE/AS and biopiling is estimated at about 400,000 m3.

6. Heavy metal contaminants were found in a disused electroplating workshop site. While the slightly contaminated soil (about 1,500 m3) was excavated and disposed of at landfill, the heavily contaminated part (about 120 m3) was treated on site using cement solidification.

Conclusions

7. All contamination hotspots that had been identified within the Kai Tak north apron area were decontaminated to the remediation targets specified in the approved EIA report or standards specified by the Director of Environment Protection.

8. Post remediation monitoring for checking any rebound of ground contamination at the previously contaminated areas is underway. There is so far no indication of re-contamination and the monitoring will continue in accordance with the requirements specified in the EM&A report.

9. Ground contamination has previously not been found in Sites 1A and 1B. Recent site investigation by Housing Department also confirms these sites are free of contamination. The housing development at these two areas should be able to proceed without affecting the on-going post-remediation monitoring.

Territory Development Department May 2002 

 

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Friday, 28 April, 2006