Report No. : GEO Report No. 53

Report Title : Environmental Aspects of Using Fresh PFA as Fill in Reclamation (1996), 46 p.

Author : K.S. Ho & P.Y.M. Chen

Abstract

In response to concerns raised by the Environmental Protection Department, a study has been carried out to examine the environmental aspects on the use of fresh PFA as fill material below water. Overseas studies, laboratory trials and case studies in Hong Kong on the use of PFA in marine conditions have been reviewed in this report.

Six laboratory trials and case studies in Hong Kong on the use of PFA below water have been reviewed. However, only a small proportion of data refer directly to the use of fresh PFA under water and therefore, the corresponding environmental impact cannot be fully assessed.

Review of study results overseas and comparison with a set of full quality guidelines from North America do not reveal major environmental problem especially if contamination of open seawater is minimised by placing the PFA in water confined by properly designed seawall. However, there remain some areas of insufficient information and until these remaining concerns are removed, the use of fresh PFA in marine reclamation has to be accompanied by a scheme to monitor environmental impact.

A set of environmental guidelines has been proposed based on the scheme used for Urmston Road project, including monitoring scheme to provide the needed field data. It is also suggested that some simple laboratory tests on the fresh PFA sample itself may be used to verify the suitability of the PFA for marine filling with acceptance criteria, on similar basis to that used for lake fill material in Canada. Such tests could be used to supplement and finally replace the time-consuming monitoring requiqments.

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