Officials say the incident is no cause for alarm as effluent is within safe levels A defective sewage outfall pipe in Victoria Harbour will be repaired this week after virtually untreated sewage was found in the middle harbour. The problem was discovered after a Post reader reported seeing murky brown water 'bubbling up' in the middle of the harbour from his Wan Chai harbour-front office. 'I noticed it a few times over the past few weeks or even months. I wondered what it was, suspecting it may be sewage,' he said. 'I also noticed that each time it happened, there were a lot of small fishing vessels around the outlet.' A Post follow-up led to an investigation by the Environmental Protection Department (EPD) and Drainage Services Department (DSD), which revealed a blockage in the pipes and a missing cover at the end of twin outfall pipes in the Wan Chai East submarine outfall. Senior DSD engineer Robin Lee Kui-biu said the cover might have been moved by an anchor or the chain on a nearby buoy. Wan Chai East is one of four outfalls off Central that are not yet connected to the Harbour Area Treatment Scheme. The preliminary sewage treatment plants at Wan Chai East and West, North Point and Central discharge effluent into Victoria Harbour after the removal of grit and solids. Sewage is pumped about 600 metres offshore, where it is dispersed with the help of water currents via a system of diffusers at the end of two outfall pipes. The blockage of the diffusers and the missing cover affected the dispersion, leading to concentrations of sewage that was visible as discoloured patches of water. But Mr Lee said although the effluent was visible, the discharge quality was within EPD standards. A spokesman for the EPD said: 'Preliminary sewage treatment works are designed to remove large solids from sewage through screening before it is discharged into the sea for dilution and dispersion. 'Wan Chai East is no exception. The treatment process involved ... limits the size of solids discharged to 10mm.' Between 120,000 and 130,000 cubic metres of effluent a day is discharged through the Wan Chai East outfall. 'During the repair works, which will take about four to six weeks, the outfall will operate at reduced capacity and 20 per cent of the flow will be diverted to the Wan Chai West outfall,' Mr Lee said. 'There will be no impact on Wan Chai West because it is operating below capacity at the moment.' A conservationist said urgent action was needed to tackle the problem. 'The issue has been dragging on for more than 10 years since a new sewage treatment scheme was first proposed,' said John Wong Man-kon, chairman of the Hong Kong Marine Conservation Society. 'The government should set a timeframe and get on with it.' As for the common practice of fishermen angling off Wan Chai pier and at other points close to the outfall points, Mr Lee said: 'I don't think it's advisable.'