Advisory Council on the Environment

Confirmed Minutes of the Special Meeting of the Advisory Council on the Environment held on 22 October 1998 at 3:00 p.m.


Mr. Peter H. Y. WONG, JP (Chairman)
Mr. Clement CHEN
Professor Peter HILLS
Mr. Joseph LAU Man-wai
Professor LAM Kin-che
Dr. NG Cho-nam
Ms Iris TAM
Miss Alex YAU
Mr. Plato YIP
Mr. Danny TSUI (Secretary)

Absent with Apologies:

Mr. CHAN Kwok-wai, JP
Mr. Barrie COOK
Mr. Paul C. H. FAN
Professor Anthony HEDLEY
Dr. HO Kin-chung
Dr. LEONG Che-hung
Mr. LIN Chaan-ming
Mr. PAO Ping-wing, JP
Mr. Otto L. T. POON
Mr. Michael J. D. RUSHWORTH
Mr. Tan Teng Huat


In Attendance:
Mr. Kim SALKELD Deputy Secretary for Planning, Environment & Lands (Environment) (DS(E), PELB)
Mr. S P LAU Assistant Director (Conservation), Agriculture and Fisheries Department (AFD) (AS(Cons), AFD)
Dr. Regina CHING Principal Medical & Health Officer, Department of Health (PMHO, DH)
Mr. David CHAN Principal Information Officer, Environmental Protection Department (EPD) (PIO, EPD)
Ms S M HUNG Assistant Secretary for Planning, Environment & Lands (Environment) (AS(E)6, PELB)
Miss Cora SO Executive Officer, Planning, Environment & Lands Bureau (Environment) (EO(E), PELB)
In Attendance for Agenda Item 1 :
Dr. Malcolm BROOM Principal Environmental Protection Officer (Water Policy and Planning Group), EPD (PEPO(WP&PG), EPD)
Dr. Samuel CHUI Senior Environmental Protection Officer (Water Policy and Planning Group), EPD (SEPO (WP&PG), EPD)
Mr. W W CHUI Senior Engineer/SSDS, Drainage Services Department (DSD) (SE/SSDS, DSD)
Mr. Peter CHAN Managing Director, Montgomery Watson (MW) (MD, MW)
Mr. Allan KWOK Joint Project Manager, MW (JPM, MW)
Professor M R HUANG Joint Project Manager, Binhai Consultants (JPM, BC)




Agenda Item 1: Further Discussion on SSDS EIA Study
The Chairman welcomed PEPO(WP&PG), EPD, SEPO(WP&PG), EPD, SE/SSDS, DSD, MD, MW, JPM, MW and JPM, BC to the meeting.
2.The Chairman suggested the representatives deal with the queries raised at the last meeting first, and then respond to his proposal and members' further questions.
3.PEPO(WP&PG), EPD said that the outstanding questions from the last meeting included the report on performance of CEPT Works at Stonecutters Island, the breakdown of statistics on population projections and the estimated costs to be recovered of sewage charges for the four options. Answers to the first two had been prepared by EPD and circulated to Members before this meeting. The answer to the last one was prepared by PELB.
4.Referring to the information paper on the recurrent cost of sewage treatment, DS(E), PELB drew Members' attention to the small proportion of costs incurred by SSDS works when compared with the total sewerage costs for the territory. Despite the likely increase in sewage charges incurred by all the four options, the charges would still be relatively low when compared with other cities like London. At the request of a Member, DS(E), PELB undertook to provide figures of sewage charges in other countries, Asian countries in particular, for comparison. In response to the Chairman's concern, DS(E), PELB said that at the moment, it was assumed that the capital costs would continue to be met through the publicly funded capital works programme.

5.A Member asked whether the costs could be reduced if the waste water was recycled. PEPO(WP&PG), EPD replied, with support from MD, MW, that though it was technically feasible, there were very little benefits, if any, to use recycled water since the costs for higher treatment level and the associated complicated infrastructural system would be high. Also, as seen in other countries, the principal use of recycled water was for large scale irrigation but there was no such requirement in Hong Kong.
6.The Chairman asked and MD, MW confirmed that if chlorine were used for disinfection prior to effluent re-use, the level of residual chlorine would not be harmful biologically but it would have other problems, such as corrosion to equipment. DS(E), PELB supplemented that instead of working on water-recycling, we should aim at saving water by other means such as "double-flushing toilets". The Chairman concurred and added that preventive rather than remedial measures should be pursued. He requested the Water Supplies Department to prepare a paper on ways to reduce water consumption.

7.PEPO(WP&PG), EPD updated Members on the TTM level. He said that the concentrations of the four main metals, copper, chromium, nickel and zinc, had dropped from 5.5 mg/l in 1988 to less than 1 mg/l in 1998, and it was anticipated that the level would further drop to 0.25 - 0.5 mg/l in the coming few years. However, there were pockets where they were still above this average.
8.Noting that the consultants had adopted a precautionary approach to recommend the use of disinfection, the Chairman asked whether the cost (capital cost $0.9 billion, recurrent cost $200 million) was justified at this stage. PEPO(WP&PG), EPD and MD, MW confirmed there were definitely marine mammals in the vicinity of the proposed outfall locations east and west of Lamma Island. Though a literature review was not conclusive on whether mammals would be affected by non-disinfected sewage, it would be safer to adopt treatment with disinfection and at the same time, build in flexibility to stop it if it was proven unnecessary in the future. Moreover, there would be a comprehensive monitoring programme to safeguard water quality and watch out for the need to re-grade the treatment level. JPM, BC supplemented that if the discharges were made in the Lema Channel, the Mainland water quality standard at the affected zone could not be achieved without disinfection, so disinfection was a must. Responding to the Chairman's concern about the feasibility of using U.V. disinfection, MD, MW said that the technology for U.V. disinfection had been developing rapidly and it was commonly used by other countries.
9.A Member asked if building a tunnel under Option 2 (Lema Channel) would experience difficulties similar to that in other tunnel projects in the past. MD, MW said although other tunnels had been built successfully, most of them only involved drilling through mountains. Nevertheless the 1.7km long under-sea interim outfall for SSDS Stage I had been successfully constructed. A tunnel into the Lema Channel could be more problematic because of the depth of the bedrock and the existence of major fault zones.
10.The Chairman asked what strategy would be adopted for sludge treatment and how much it would cost to incinerate different amounts of sludge generated from different treatment levels. PEPO(WP&PG), EPD pointed out that for all the options investigated, the problem of sludge disposal was a common feature. There were certainly differences in quantity but not so much as to be a major factor in the choice of option. He noted also that if incineration was adopted for sludge disposal, the contribution of incinerated sludge residue to the total landfill intake would be very small and hardly likely to make a meaningful contribution to the exhaustion of landfills. As a comparison, he pointed out that the landfills currently received about 8,500 tonnes per day of municipal waste and a further 6,000 to 8,000 tonnes per day of construction waste, while the estimated amount of sludge residue under Option 1, after dewatering and incineration, would be only 140 tonnes per day.
11.The Chairman asked whether Hong Kong would follow the example in Australia where untreated sewage was discharged into the Port Phillip Bay. MD, MW clarified that according to his information two of the three main sewage treatment facilities in Melbourne discharged biologically-treated sewage outside the bay specifically to prevent a build-up of nutrients in the bay. At the third facility the sewage was treated in lagoons covering some 10,000 ha of land. Part of the high quality effluent was recycled and the remainder allowed to discharge to the bay.
12.In response to a Member's concern, MD, MW replied that even though the deep tunnel outfall in Sydney was 4 km long to prevent the discharge from flowing back to the beaches, they still needed non-stop comprehensive monitoring programme to ensure the safe dispersion of the discharge.
13.A Member asked whether screened or primary treated sewage discharged to a longer outfall would meet the Mainland Water Quality Objectives (WQO). The Chairman remarked that water quality in the Pearl River Delta (PRD) also did not meet the standard. In response to that Member's query, PEPO(WP&PG), EPD confirmed that a discharge in the Lema Channel of undisinfected sewage would have a very large mixing zone within which the mainland bacterial WQC would not be met. In response to the Chairman's remark, MD, MW pointed out that what mattered was the standard and the prevailing conditions in the Category I waters where the treated effluent would be discharged. PEPO(WP&PG), EPD pointed out that Shenzhen was moving forward with the provision of new sewerage and according to their projections, by 2000 over 70% of the sewage would either be transported westwards and discharged into the Pearl River or would receive secondary treatment. It should therefore not be assumed that Shenzhen was not dealing with its sewage. The Chairman asked PEPO(WP&PG), EPD to provide information on Shenzhen's waste water treatment/management facilities. PEPO(WP&PG), EPD also noted that the main impact of the Pearl River on Hong Kong water quality took the form of relatively high nutrient levels, and these were more likely caused by run-off from the land than untreated sewage discharges. He added that joint efforts between the two sides to improve the water quality had been put on the agenda of the Hong Kong / Guangdong Environmental Protection Liaison Group meetings.

14.In response to a Member's query, JPM, BC said that although it was technically feasible to use recycled sludge for agricultural purpose, it would be difficult to find a market because firstly the farmers in the Mainland preferred chemical fertilizers, and secondly the sludge in the Mainland was already excessive and was either landfilled or incinerated.
15.With regard to the concern about safety measures against malfunction of any component of the SSDS, MD, MW explained, taking the Stonecutters Island Sewage Treatment Works (SISTW) as an example, that there would be standby or spare components including two different power supplies for the plant. SE/SSDS, DSD supplemented that the design of SSDS Stage I allowed the sewage to by-pass the treatment plant and be discharged via the Stage I outfall in case of a shut down of the treatment plant. Principal Assistant Secretary (Environment)3, Planning, Environment and Lands Bureau (PAS(E)3, PELB) supplemented that in the unlikely case of a total breakdown of the SISTW, the sewage would still receive preliminary treatment through existing screening plants in the SSDS catchment prior to discharge. PEPO(WP&PG), EPD said that roughly similar risks of failure existed in all options and that the best way of dealing with the risks was to "design-in" appropriate safeguards.
16.The Chairman requested the Administration to provide further information on the following issues to facilitate Members' better understanding of the development of the SSDS:
(a) 'desk top' geological survey on the long outfall alignment and location and proposed design options for the outfall, i.e. tunnel or surface conduit, etc.;
(b) complete comparative costing of different treatment levels and in particular costing of 'the way ahead' option as envisaged including Net Present Value analysis, for the front runner options;
(c) information on Shenzhen sewage treatment scheme;
(d) report on feasibility of joint discharge with Shenzhen;
(e) water pollution status in PRD Region and in Deep Bay; and
(f) commentary on 'risk assessment' for SSDS specially as it related to malfunction of major components.

17.With reference to the preliminary costing, PEPO(WP&PG), EPD provided a rough estimation as follows :

  capital cost recurrent cost
CEPT + disinfection
(Option 1)
$11.8b $0.87b
CEPT $10.9b $0.67b
primary treatment $12.6b $0.67b

The capital cost of primary treatment was higher than CEPT because another site for the treatment plant would need to be constructed. There was insufficient space on Stonecutters Island. The recurrent cost savings would be limited to those achieved by dropping disinfection. There was no difference between the two "no disinfection" scenarios because savings on chemicals achieved by going to simple primary were offset by the increased costs of running two plants.

18.In response to a Member's question, MD, MW said that there was hardly any geotechnical problem which could not be overcome in Stage I. The only problem they had had was the quitting of the contractors and the additional time needed for the three new contractors in resuming the works and to mobilise equipment. However, Stage I works should now be finished by 2000. The Chairman asked DSD to provide a quarterly report on the progress of SSDS Stage I to keep the Council informed of the latest developments.

19.At the Chairman's invitation, a Member summed up the discussion that the Council had no dispute on the options which should be considered in the context of trade-offs between costs and environmental benefits. The options chosen should be flexible enough for future upgrading or downgrading. To formulate its recommendation, the Council had to satisfy itself in three areas, namely the need for adopting the precautionary principle in using disinfection, ruling out the possibility of using preliminary treatment with a long outfall, and dropping option 2 due to geotechnical problems. Also, any other solution through collaboration with the Mainland should be explored.
20.The Chairman added that sludge management was a major concern in choosing an option. PEPO(WP&PG), EPD said unless one advocated screening only as being explored by the Chairman, the problem of sludge management was common for all four options. He assured Members that EPD would report the findings and recommendations of the sludge management strategy study early next year.

21.The Chairman asked and DS(E),PELB confirmed that land could be reserved on Lamma Island for future upgrading of treatment level if found needed. The Chairman then requested an estimate of the number of years needed for the land reservation.

[Post meeting note : The land would have to be reserved until the actual impacts of the adopted option had been assessed. This would take about three years after commissioning.]

22.In response to the Chairman's query, MD, MW said that it would be feasible, purely from the engineering point of view, for Shenzhen to jointly dispose their sewage through Hong Kong's facilities. However, additional facilities would need to be constructed.
23.Referring to ACE paper 37/98 under discussion, the Chairman said advice was sought from the Council in two respects. First, Members agreed that the discharge from the SSDS Stage II should be disinfected to remove 99.9% of bacteria by using U.V. subject to satisfactory results of the EIA Study. Second, for the option to be pursued, the Council saw the need to take into account factors like costs, completion time and feasibility. However, a Member believed that in deciding which option to be recommended by this Council, focus should be on environmental aspects while political and geotechnical problems should be set aside. Being cautious not to rule out any option with uncertainties at present, another Member asked how long the consultants would take to report on the geological condition of option 2 with uncertainties associated with the fault zones. MD, MW said that it would take at least one year for investigation, and suggested it would be possible to move forward with, say, Option 1, while retaining the flexibility to pursue other options at a later date when, for example, more information on ground conditions was available.
24.JPM, BC commented that although the hydrodynamic condition was better in respect of option 2, it would however cost $2 billion more than option 1, and if no disinfection was provided, the sewage still could not meet the WQC in the Mainland. SE/SSDS, DSD added that option 2 would post geotechnical as well as operational risks. In response to the Chairman's comment on the under-achievement of WQC in the Mainland itself, MD, MW said that the Mainland had a long term plan to solve the pollution problem in the whole Pearl River estuary.
25.Finally, the Council agreed that option 2 should be preferred on the condition that it would be flexible in re-grading the treatment level up or down while option 1 should be the fall back choice if option 2 turned out to pose insurmountable problems.

Planning, Environment and Lands Bureau (Environment Division)
November 1998


Back to topdot_clear.gifTable of Content
User defined date2: 
Friday, 28 April, 2006