In the next 10 years, to enhance our water quality and protect public health the Government plans to invest about $20 billion in new sewerage and sewage treatment facilities - about as much as it has invested in the last two decades.

As well as the capital cost, which the Government will pay, there will be additional operating costs of about $1.3 billion a year. We are glad the adoption of the polluter-pays principle has taken root in the community.

The firm support expressed by Legislative Council members has also laid the cornerstone of the package of measures needed to take our sewage services to the next level.

Legislation for the proposed increases in the sewage charge is now before LegCo. The average monthly domestic sewage charge at the moment stands at $11 per account.

To fund the operating costs of our planned sewage services that will have to rise to $27 in 10 years' time. This translates to a modest increase each year over a period of 10 years of no more than 10 cents a day.

The arrangement will provide predictable, sustainable and stable funding support to the operation of these important facilities.

Subject to the smooth and speedy passage of the legislation, the Government will seek funds for the construction of the centrepiece of the future programme, namely the Harbour Area Treatment Scheme (HATS) Stage 2A which will finally rectify the highly unsatisfactory situation that sees hundreds of thousands of tonnes of wastewater still being discharged largely untreated into Victoria Harbour daily.

HATS 2A will involve collecting the untreated sewage from the north and west shores of Hong Kong Island and transferring it through deep tunnels to Stonecutters Island for chemical treatment before disinfection and discharge in the western anchorage area.

It will cost $8 billion to build and about $420 million a year to operate, but when commissioned in 2014 it will improve water quality, and reduce the bacterial levels in the main harbour area by 90% so that we will finally be able to resurrect the annual cross-harbour swim and hold other water-based recreational activities.

To bring about early improvements in the western harbour we plan to advance the disinfection facilities so that they can be completed in about two years' time and allow early re-opening of some of the closed beaches in the Tsuen Wan district.

To achieve this early benefit, a technical option is to chlorinate the effluent to kill the germs, then dechlorinate it to remove any residual chlorine. The environmental impact of this is being assessed in a study, the findings of which would be subject to public inspection and comment under the Environmental Impact Assessment Ordinance.

Some environmental professionals have raised concerns about the potential environmental impact of chlorination. However it is relevant to note that chlorination is a widely used disinfection technique for treated sewage effluent. Its use continues to be adopted in many places overseas, with the appropriate dechlorination step added to remove the residual chlorine.

On the other hand, because of land zoning and the possible need for a new power sub-station, the adoption of UV for disinfection will take substantially longer to deliver and could only be brought on stream at the same time as the main Stage 2A works are commissioned in 2014.

A lot of people in the community would prefer not to have to wait that long to be able to access recreational facilities near Tsuen Wan again. And rightly so.

Some people argue that Stage 2A will not be enough and a higher biological level of treatment - HATS Stage 2B - is required. We agree and have already commenced the necessary procedures on land and related matters for planning of HATS Stage 2B.

We have also made a public commitment to thoroughly review in 2010/11 how this important next step should be implemented. This is prudent and responsible given that the scale and complexity of the biological treatment operation under contemplation are unprecedented and the implementation constraints in terms of land availability and project interface are complicated.

On the land requirement, we have identified a site close to Stonecutters Island Sewage Treatment Works for HATS 2B which has the potential for accommodating the treatment facilities under HATS 2B on a co-use basis. However, this naturally means that the originally intended use for the site must be settled before design work can start.

On the other hand, recent indications are that the population growth is slower than earlier forecasts and hence the build-up in sewage flows and the consequential water quality impact will be less than earlier predicted.

This therefore allows us more time to keep pace with the technological advancement so that the optimal biological treatment system can be adopted in the eventual HATS 2B.

In fact, during the implementation of HATS Stage 2A, planning work for Stage 2B, such as assessing the environmental impacts, site investigations and land reservation, will go full steam ahead in parallel. Therefore, there is no question of any lack of commitment to HATS 2B.

Moving forward to clean seas and clear waters, this common goal is within grasp.

This article from the Secretary for the Environment, Transport & Works was published in several Hong Kong newspapers.