Mud disposal report was not a whitewash

As one of the authors of the EVS Environment Consultants' report cited in your March 24 article headlined, 'Mud pits 'dangerous for white dolphins' ', I would like to express appreciation to Fiona Holland, for accurately quoting our conclusions.

However, I take exception to the comments by Friends of the Earth branding the conclusions a 'whitewash'. For the record, our report was reviewed by senior technical staff of the Environmental Protection Department (EPD), the Agriculture and Fisheries Department, the new Airport Projects Co-ordination Office, and the Civil Engineering Department, all of whom agreed that all the available data and information available consistently supported the conclusions.

This report together with a large number of other technical studies undertaken for the Hong Kong Government by EVS and others, represents a very substantial effort to determine if disposal operations at East Sha Chau have been environmentally acceptable and whether the area is a suitable site for such operations.

The short answer to these questions is in the affirmative. The reports have been presented to and accepted by the Advisory Council on the Environment, as well as being provided to interested parties. This is no 'whitewash'.

The EPD has set very conservative levels for classifying dredged material. The seven metals which are used for sediment classification and regularly monitored in the dredged spoil, occur naturally in the marine environment as part of the chemistry of sediment, soil and water.

If even one metal is elevated a small amount above background the mud is considered 'contaminated', and is designated for disposal at the contained facility at East Sha Chau. Consequently, much of this mud is not toxic, which is confirmed by toxicity tests on the sediments so far.

The disposal operations use 'confined aquatic disposal' where all the dredged mud is disposed in excavated pits, and capped with clean marine mud, so as to isolate any contaminants from the environment.

The entire operation is managed by a 24-hour on-site management team and the water, sediment and marine life in and around the disposal area are monitored by a comprehensive programme. 'Dilution' is not used as the 'solution to pollution'.

No evidence means that no impacts from contaminated mud have been detected in over four years of monitoring and testing.

This monitoring is ongoing, and I submit that this information together with other environmental monitoring and research programmes is very good evidence of our conclusions. Attempting to put blame on East Sha Chau for stranded dolphin mortalities for which there is no basis, does not benefit the cause of the Chinese white dolphin. It simply draws attention away from broader issues such as contaminants from the Pearl River Estuary, pathogens from sewage discharge, collisions with high speed vessels and net entrapment.

I would encourage those with concerns for the Chinese white dolphin to make use of the large amount of information that has been, and continues to be developed on pollution effects and sources to set the right directions to protect the dolphin.

Dr GARY A. VIGERS EVS Environment Consultants Vancouver, Canada