Disposal of contaminated mud in Hong Kong: A review of the environmental monitoring programme

Hong Kong has undertaken very extensive dredging works in recent years. It is estimated that in the 10-year period up to 2002, a total of some 40Mm 3 of material classified as contaminated will have required dredging and disposal elsewhere. Contaminated dredged material has been disposed of into pits excavated in the bed of the Pearl River Estuary in an area of relatively shallow water depth and low current velocity since 1992. These pits are subsequently capped to ensure isolation of any potential pollutants from the wider marine environment. The disposal operations are subject to a rigorous monitoring and audit programme in order to confirm the effectiveness of the disposal strategy in containing contaminated material and to demonstrate its environmental acceptability. The monitoring work has included testing of the integrity of pit caps, sediment plume tracking, analysis for trace contaminants in sediments, marine water and biota, alongside study of benthic and epifaunal ecology. The key findings of the environmental monitoring programme are presented and the way forward for future work is discussed.