PELB(E) 55/10/161 Pt 29

Tel : 2848 2606
Fax : 2530 5264

14 June 1999

Clerk to the LegCo Panel on
Environmental Affairs
LegCo Secretariat
3/F, Citibank Plaza
Garden Road
Hong Kong

(Attn : Miss Odelia Leung)

Dear Miss Leung,

LegCo Panel on Environmental Affairs
Meeting on 11 June 1999
Follow-up Actions

As requested by the Panel at its meeting on 11 June 1999, I enclose the Executive Summary of the EIA reports for the Cheung Chau Sewage Treatment Works (STW) submarine outfall (para. 17 of LegCo Paper CB(1) 1442/98-99(02) refers) and the Ting Kau and Sham Tseng Sewerage Scheme (para. 23 of LegCo Paper CB(1) 1442/98-99(03) refers) for Members' reference.

At the meeting, some Members asked about the possibility of providing secondary treatment at Cheung Chau and Sham Tseng. We explained that for the Cheung Chau STW which was commissioned in December 1984, our current proposal was to improve the existing facilities by replacing the existing submarine outfall with a new and longer outfall and upgrading the existing sludge dewatering facilities. The EIA study for the Outlying Island Sewerage Stage I Phase I works completed in October 1997 concluded that the existing primary treatment process plus the improved dilution effect provided by the new outfall would allow the relevant water quality objectives to be met. Nevertheless, we would review the need for upgrading the plant to secondary treatment.

For the Ting Kau/Sham Tseng Sewerage Scheme, we explained that the proposed sewage treatment works would provide chemically enhanced primary treatment (CEPT) which would fulfil the water quality objectives of the adjacent water body. As a precautionary approach, disinfection of the treated effluent will be provided to give added protection to the marine ecology including the Chinese White Dolphins. We undertook to provide a comparison of the cost estimates for secondary treatment at Sham Tseng STW for Members' reference. This is attached at Annex. Apart from cost considerations, a change in design would lead to a minimum delay of 12 to 18 months in the programme because of the need for additional investigations, EIA study and contract documentation. Besides, the existing allocated sewage treatment works site of 11,000m2 will not be sufficient for a secondary treatment works.

Yours sincerely,

(Danny Tsui)
for Secretary for Planning,
Environment & Lands


Ting Kau/Sham Tseng Sewerage Scheme

A comparison of the cost estimates for CEPT
and secondary treatment plants

Secondary +
(based on a sequencing
batch reactor process
Capital cost estimates$220 million $297 million
Recurrent cost estimates$12 million $18 million
Land requirement estimates11,000m214,000m2