THE Environmental Protection Department (EPD) is investigating a possible flow of mud contaminated with heavy metals into Hong Kong waters off Sha Chau during Typhoon Koryn in June. The EPD said in a brief statement that investigations being carried out in Hong Kong and the Netherlands, where samples of the mud have been sent for analysis, would determine if the mud was contaminated. Barges laden with contaminated mud from reclamation sites regularly dump their loads into a special pit dug into the sea bed east of Sha Chau. According to the EPD, there was a report made after Typhoon Koryn that contaminated mud had been found near the mud pit at East Sha Chau. ''As the investigation is in progress, it is not possible to say at this stage whether mud has escaped from the pit, [whether] there has been a case of illegal or short dumping, or if there was nothing wrong at all,'' said the EPD. The World Wide Fund for Nature said it was concerned about the potential for contaminated mud to flow from the two pits east of Sha Chau during typhoons and called on the EPD to make its findings public. The EPD said the results would be available at the end of September. The Civil Engineering Department (CED), which manages the East Sha Chau pit, was conducting a bathymetric survey of the pit. Binnie Consultants, who monitor the pits for the CED, acknowledged yesterday that there was a risk that mud could flow from the pits during a typhoon due to the sea bed being disturbed. But a spokesman said that routine monitoring of the pits had not uncovered any problems. ''We warned a long time ago that, obviously, with a typhoon going through there's an increased risk of material getting out of the pit,'' the spokesman said. Binnie Consultants, in conjunction with an environmental consultancy, said water samples were collected from pit sites after a typhoon. The samples were then sent to the Netherlands to be analysed using a technique known as elemental fingerprinting, which was not available in Hong Kong. Joanna Ruxton, the World Wide Fund for Nature's marine conservation officer, said if mud contaminated with toxins leaked into the sea it could kill marine life. ''The idea is when it [the pit] is full they will cap it with clean mud, but [in the meantime] as these barges are continually dumping toxic mud there, then that's what is available to any animals that are feeding or foraging in the area,'' she said. The CED has confirmed that the pits have to be dug under shallow water so that when barges discharge their loads into it, the mud will not have far to drop through the water column and will not disperse. The pits are not capped until they are full.