Environmental authorities have drawn fire for covering up the scale of effluent leaks from landfills, after a top official admitted that seepage from the Ta Kwu Ling tip was not an isolated case.
The landfill in Tuen Mun was similarly plagued by the problem, assistant director David Wong Tak-wai of the Environmental Protection Department said yesterday.
But the department released a statement last night rejecting Wong's admission.
The statement conflicted with evidence provided by residents in the area and fuelled speculation on the extent of the cover-up.
The controversy arose on Wednesday when the department disclosed the Ta Kwu Ling landfill had been leaking liquid waste that might contain a high level of ammonia into the Kong Yui Channel, which flows into the ecologically sensitive Deep Bay.
Both landfills are operated separately by two contractors that belong to the same parent company, Suez Environment.
Yesterday morning, a Tuen Mun resident said on radio that in July last year, the dump in her area was also found to be leaking. The incident polluted water in Ha Pak Nai, Yuen Long, she said.
Wong replied that the department had planned to prosecute contractor Sita Waste Services. "We obtained a water sample and were ready for prosecution. But the evidence was found to be insufficient after we sought legal advice from the chief justice."
The Tuen Mun dump is said to have been leaking for a long time. Two residents of Ha Pak Nai backed up the complaint with their own experiences.
Cheng Wai-kwan said the leakage threatened his oyster farm near Deep Bay last July. "The crushed rubbish, together with the leachate, is often discharged into the sea whenever there's torrential rain. This is almost a yearly affair."
Another resident, To Sik-yu, presented a letter the department sent to him in July 2011 after he lodged a complaint. The department wrote that the impermeable layer at the base of the landfill was damaged. It said that on July 19, officers found the tip discharging muddy water and rubbish into a big nullah.
In its statement last night, the department sidestepped the claims, including Wong's admission. It said investigations held last year found no leachate leak and the discharge was only a surface run-off due to heavy rain.
Contractor Far East Landfill Technologies reported the Ta Kwu Ling leak on July 28.
The department took a further month to disclose the matter.
Explaining the time lapse, it said that results of tests on water samples showing the pollutants had exceeded legal limits only came in on Friday last week.
It added that it might prosecute the contractor.