Q&A on Lamma Sewage System with EPD and DSD 14 June 2010

Responses  from the Environmental Protection Department and the Drainage Services Department presented by CK Au, Engineer 3, DSD

Q1. We understand that the government is just putting in the main sewage pipes and then it is up to the individual homeowners to connect to the mains. How will this work in practice? For houses where there is only one homeowner, this might be simple, but typically on Lamma the houses are sub-divided into 3-6 flats, some with multiple owners. Often these owners are absent and in some cases they cannot be traced. If you own a flat in a block like this, will it be possible to just pay your portion of the connection charge? It would be unfair for the burden of this charge to not be distributed evenly. Can you explain how this will be administered? There is also concern that if individuals have to find their own contractors without any independent oversight from government, then there is a high risk of abuse both from the point of view of over-charging and on the standard of work provided.

A1. Upon completion of the main sewer laying works, EPD and DSD will arrange briefing for the concerned villagers and explain to them the required house connection process, the extent of works involved and the legal implication. Where appropriate, the Government will also help resolve specific problems that may arise. Based on our previous experience, with the above liaison work and assistance offered, the majority of the concerned villagers will generally co-operate and eventually carry out the required house connections.

For a multi-units village house, it is not uncommon that all unit owners would need to take up jointly and severally the improvement or maintenance works for common facilities/utilities/building-areas of their premises and to share the costs of the works among themselves. The sewer connection work is a typical example of this kind of works that require a coordinated and joint effort from the unit owners. This situation is quite common in other outlying islands. The unit owners would usually liaise amongst themselves on the detailed arrangement to implement the works and to share the costs. If necessary, they would seek assistance from DO/Islands or the District Council members of their respective districts.

The section of sewer (from the premises up to the terminal manhole) and the terminal manhole are solely private in nature, thus the unit owners should make their own arrangement for the construction and maintenance of these private properties. In serving the notice for making sewer connection, EPD would enclose all necessary details including the position and specifications of the terminal manhole to be required. The completed sewer connection work would be inspected by EPD while the completed terminal manhole connecting to the public sewer would be inspected by DSD.

Q2. What will happen to the existing septic tanks? We assume that they will have to decommissioned. How will this be done and who will pay for this?

A2. Upon the completion of the sewer connection work, the septic tanks would be left unused. The houseowners should be responsible to remove or fill up the septic tank afterwards and notify Lands Department for record. Houseowners can include the decommissioning of septic tank as part of the sewer connection work and require the contractor to complete it as well.

Q3. Can you explain about the sewage outfall? While most of our members think the sewage system is a good thing, many are worried about the environmental consequences of sewage outfall. Outfalls are widely recognised as major sources of contaminants to coastal ocean ecosystems.

A3. There is a general impression that outfalls are sources of contaminants to coastal ocean which generally refers to stormwater outfalls coming out from seawalls in particular when surface sediments and dirt are often being washed down to the stormwater system during rainfall event.

For this Lamma Island Sewage Collection, Treatment and Disposal project, two new sewage treatment works will be built to provide secondary treatment to the sewage collected in Yung Shue Wan (YSW) and Sok Kwu Wan (SKW) respectively. The treated effluent will visually be clear water. The sewage outfalls in YSW and SKW will be submarine outfalls extending about 500m and 750m respectively from coastline with the discharge point at the outermost end.

The discharged effluent will be diluted efficiently in the open sea meeting all established environmental requirements and standards. The project consultants had reviewed the Environmental Impact Assessment which conducted a few years ago and carried out water quality modelling at the design stage. The result of the water quality modelling revealed that the water quality impact of the effluent discharge from the submarine outfalls at YSW and SKW is negligible and no significant adverse impact is anticipated during the operation phase of the sewage treatment works.