Final breakthrough has been achieved on the Hong Kong Drainage Services Department’s Harbour Area Treatment Scheme (HATS) Stage 2A. The breakthrough on the section crossing Victoria Harbour connecting Sai Ying Pun and Stonecutters Island marked the completion of the 21km of sewage tunnel on the scheme designed to further improve the water quality of Victoria Harbour.
The sewage tunnel is the deepest in Hong Kong with the lowest point being 163.8m below sea level. The works under Stage 2A commenced in July 2009, comprising the construction of the 21km of sewage tunnel using drill-and-blast for shaft excavation works and deep tunnel construction. Consultant for the sewage conveyance system is AECOM Asia Company Ltd, with tunnelling carried out by contractors – Gammon Construction Ltd, Leighton/LNS JV, and Paul Y Construction Company Ltd.
Officiating at the breakthrough ceremony on October 6, the Secretary for the Environment, Mr Wong Kam-sing, said upon the commissioning of Stage 2A, all the sewage generated from both sides of the Harbour will be treated at a daily capacity of up to 2.4 million cubic metres, further improving the water quality of the Harbour. Moreover, when the Sludge Treatment Facility in Tuen Mun commences operation early next year, the sludge generated will be transferred to the facility for high temperature treatment, turning waste into energy and reducing the burden on landfills.
Since their opening in late 2001, the facilities under HATS Stage 1 have provided daily treatment for about 75 per cent of the sewage generated from both sides of Victoria Harbour, significantly improving the water quality in the eastern and central parts of the Harbour. Stage 2A will mainly collect sewage from the northern and southwestern parts of Hong Kong Island and convey it to the Stonecutters Island Sewage Treatment Works for treatment and discharge.