Three months for full rehabilitation of Sai Kung Sewage Treatment Works

sewage works
Aerial view of the sewage treatment works showing outflow of partially treated sewage               Photo: Waly Lee

It could take up to three months to fully repair the damage caused by Super-typhoon Mangkhut at Sai Kung Sewage Treatment Works according to Drainage Services Department (DSD). They pointed out that due to the wide range of damage  at the treatment plant, rehabilitation work is very complex and they expect to resume secondary sewage treatment services within three months.

DSD said that in addition to part of the outflow and some building damage, the plant’s main sewage treatment facilities, including ultraviolet disinfection systems and secondary sewage treatment equipment, along with other equipment such as aerators, power systems and sludge pumps were also damaged. The seawall of the sewage treatment plant and the inner carriageway of the plant were also severely damaged.

The Department expects that temporary facilities will be completed in the next two weeks by making an upgrade so that the system is working to the highest chemical treatment level.

According to water quality test results of the waters and beaches close to the sewage works, the sample taken from the surface of the pumping station on the 24 September was 600 E. coli per 100 ml. Then it surged to 2200 E. coli per 100 ml. According to the standards of the Beach Monitoring Scheme of the Environmental Protection Department, these would be graded as poor and extremely poor respectively.

According to DSD, water discharged from the sewage works is only going through a primary treatment and disinfection process, where it is then taken through some rehabilitated pipes to the original deep sea pipeline and discharged into the sea 400 metres away from the plant to enhance dilution.

DSD has indicated that the second phase of the improvement works for the sewage works will be completed in the future. The results of the “Feasibility Study on the Relocation of the Sai Kung Sewage Treatment Works into a cave” and the planning of the “Second Phase of the Niu Mei Sewage Project” Scheme will be implemented as soon as feasible. The timetable for the project is currently under review.

The Sai Kung Sewage Treatment Plant is a secondary sewage treatment plant. In recent years, the processing capacity has exceeded 12,000 cubic metres per day, and the average sewage treatment volume in the past eight months is 9,600 cubic metres per day.

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