PLC Panel on Environmental Affairs

Sewage Leaks Resulting in the Temporary Closure of Beaches in Tuen Mun & Stanley

Supplementary Information

Introduction

An information paper on the captioned subject was circulated to Panel Members on 31 July 1997. This supplementary paper updates Members on the progress in the improvement measures taken.

Repair of the sewage outfall pipe at Tuen Mun

2.The contractor who damaged the outfall pipe has carried out repair works. The major damage was repaired on 10 July 1997 but some leakage was still observed in subsequent tests. After a number of trials, the contractor has recently reported that the repair works have been completed. A joint diver inspection carried out by DSD and the contractor is being arranged to check the structural integrity of the whole damaged pipe to ensure that there are no more leaks before it is put back to operation. At present, modification works to the sewage treatment works have been installed such that all the screened sewage is effectively discharged through the undamaged outfall pipe under all flow conditions.

Drawing up of an emergency action plan for improvement of communication between DSD and EPD

3.Since the end of July 1997, new measures have been put in place for better communication between DSD and EPD officers regarding sewage incidents. The relevant Chief Engineer of DSD shall inform the Principal Officer of the relevant EPD Local Control Office by phone and by facsimile regarding such incidents. If there is a possibility of beach water quality being adversely affected so that swimmers might be at risk, EPD will inform USD or RSD of the incident. EPD will also conduct an investigation to assess the position before advising USD or RSD further on the suitability of beach water quality for swimming.

4.In addition, a more formalised beach pollution response plan has been drawn up to set out clearly the required emergency responses and actions to be followed by the departments concerned. The response plan includes details such as beach catchment maps, action flow charts and telephone/facsimile numbers of the first and back-up contacts of concerned departments (e.g. EPD, DSD, USD, RSD, HAD) for each gazetted beach. This plan is being implemented for the remaining part of the 1997 bathing season.

Beaches susceptible to sewage pollution from damaged outfall pipes

5.Of the 41 gazetted beaches, only 10 beaches have submarine outfall pipes in the vicinity. The chance of bursting or being damaged by others is normally very remote because all submarine outfall pipes are protected by rubble mounds which are capable of withstanding the impact load of marine traffic. Regular inspection, testing and maintenance of submarine outfall pipes are carried out at fixed intervals to ensure there is no leakage in the outfalls. Nevertheless, in order to prevent the recurrence of the Tuen Mun incident, for marine works in the vicinity of submarine outfalls, the contractor of the works will be required to submit a statement of his construction method to DSD for approval prior to commencement of works and to delineate restricted zones over the submarine outfalls with marker buoys to facilitate the monitoring by DSD operating staff.

6.A small consultancy study will be funded by DSD and managed by EPD to examine a shortlist of beaches to advise on the short and long term measures to reduce and eliminate the risks caused by polluted discharges to these beaches. The study is expected to start in September and complete by the end of 1997.

Beach monitoring and laboratory analysis

7.In view of increased public concern on the pollution of beaches, EPD have, since 1 August 1997, increased the frequency of beach monitoring to weekly during the bathing season. This enables EPD to issue the beach grading results weekly (every Friday) instead of once every two weeks. The first of these weekly press releases was issued on 8 August 1997.

8.A new laboratory analytical method is now being used for the analysis of beach water samples. This new method is quicker and more specific for the determination of E.coli. The time required for analysis has been reduced from three days to one and a half days.

Works Bureau
21 August 1997