The Environmental Protection Department (EPD) received complaints last year that the flaring temperature of the landfill gas treatment facility of PPVRL had failed to reach the contractual requirement of 1 000 degrees Celsius, leading to the discharge of sub-standard leachate into the foul sewer and untreated leachate into a nearby stream.
An investigation team was subsequently set up by the EPD to conduct thorough investigation on the complaints.
A test conducted by the investigation team on-site in May 2016 found that the leachate treatment plant failed to handle leachate effectively, and was therefore required to suspend operation to conduct thorough repair works.
Regarding whether sub-standard effluent had been discharged from PPVRL, the investigation found that the leachate concentration was at relatively low levels as the landfill had been closed for many years and sometimes the leachate could meet the dry season discharge standard even without pre-treatment.
However, since the mixing of leachate could not meet the wet season discharge standard, the investigation team could not exclude the possibility that sub-standard discharge had happened given that the treatment plant could not handle the leachate effectively.
The follow-up actions taken by the EPD’s enforcement team found that the discharge of the leachate treatment plant during the period from May to mid-October 2016 repeatedly contravened the requirements of the licence issued under the Water Pollution Control Ordinance.
It was found that the total nitrogen level in the discharge exceeded the specified limit in the licence on eight occasions, the amount of discharge exceeded the discharge flow limit specified in the licence on 10 occasions, and the contractor also failed to notify the EPD immediately on two occasions when the amount of discharge exceeded the discharge flow limit.
The investigation team had referred the relevant information to the Police for follow-up on whether someone had deliberately provided inaccurate data or false statements to the EPD.
As the leachate treatment plant has failed to meet the contractual requirements of treating leachate effectively, the EPD has deducted operation payments according to the contract provisions.
The EPD will continue to closely monitor the operation of PPVRL.