2 PROJECT DESCRIPTION.. 1
2.1 Site Location. 1
2.2 EIA Study Area. 1
2.3 Project Requirements,
Scope and Benefits. 2
2
PROJECT DESCRIPTION
2.1
Site Location
2.1.1
A
new sewage outfall will be constructed under the project at the Wan Chai North
waterfront to replace and upgrade the existing Wan Chai East sewage
outfall. The location of the Wan
Chai East sewage outfall is shown in Figure 1.2e.
2.2
EIA Study Area
2.2.1
The
following definitions of the study areas have been adopted with reference to
the EIA Study Brief registered under the EIAO:
·
Air
Quality Impact: the assessment area should include the area within 500 m from the boundary of the Project;
·
Noise
Impact Assessment: the assessment area should include the area within 300 m from the boundary of the Project;
·
Water
Quality Impact Assessment: the assessment area should include the areas within
and 300m extended beyond the boundary of the Project, plus the Victoria Harbour
Water Control Zone (WCZ), the Eastern Buffer WCZ and the Western Buffer WCZ as
declared under the Water Pollution Control Ordinance;
·
Waste
Management: the assessment will focus on areas within the boundary of the
Project;
·
Land
Contamination: the assessment area for land contamination impact will include
any potentially contaminated sites identified in this EIA;
·
Landscape
and Visual Impact: the area for
landscape impact assessment should include all areas within 100 m extended from the boundary of the Project, while the assessment area
for the visual impact assessment should be defined by the visual envelope from
the Project and associated works;
·
Marine
Ecology: the assessment for marine ecological impact will focus on the area
within the Project boundary; and
·
Cultural
Heritage Impact: the assessment for cultural heritage impact will focus on the
area within the Project boundary.
2.3
Project Requirements, Scope and
Benefits
Project Scope and Requirements
2.3.1
The
Wan Chai West Sewage Screening Plant will be decommissioned once flows have
been diverted to the Wan Chai East Sewage Screening Plant. The Wan Chai East Sewage Screening Plant
will have adequate capacity to handle these flows. However, in the longer term, the
existing sewage outfall will need to be upgraded to handle the future design
flows. A new sewage outfall will be
constructed under the project to replace and upgrade the existing Wan Chai East
sewage outfall. The configuration
of the new sewage outfall will comprise a landfall section of 2,250mm diameter pipe with
approximate length of 180m,
and a marine section of twin 1,600mm
diameter submarine pipelines of about 550m length.
Project Benefits
2.3.2
The
existing sewage outfall has to be reprovisioned to enable the construction of the
reclamation and Trunk Road. The
project provides opportunity to upgrade the sewage outfall to handle the future
design flows.
Consequences of Not Proceeding
with the Project
2.3.3
Should
the existing sewage outfall not be reprovisioned under the Project, the
existing sewage outfall will be damaged by the reclamation works and the
construction of the Trunk Road.
Without a sewage outfall, the Wan Chai East Sewage Screening Plant
cannot operate.
2.4
Development Alternatives
2.4.1
The
alternative to constructing a new sewage outfall to reprovision the existing
one is to construct a deck-over structure above the existing sewage
outfall. However, this alternative
option is considered not feasible as the Trunk Road tunnel will be crossing the
existing pipeline at the same level and there will be problems for future
maintenance of the pipeline below the deck structure. Construction of a new sewage outfall is
considered a reasonable and practicable solution.
2.5
Construction Methods and Engineering
Requirements
2.5.1
The
configuration of the new sewage outfall will comprise a landfall section of 2,250mm diameter pipe with
approximate length of 180m,
and a marine section of twin 1,600mm
diameter submarine pipelines of about 550m length.
Based on preliminary assessment, this configuration will have capacity
to cater for a design peak flow of 4,613 l/s.
2.5.2
The preliminary analysis has been based on the new
outfall having similar configuration to the existing, with similar diffuser
arrangements. The hydraulic
performance of the new outfall, and the efficiency of the diffusers will be
assessed more thoroughly in the detailed design stage.
2.5.3
The construction method for the submarine pipelines
involves dredging for a pipe trench and laying of bedding materials, pipelines
and covering materials by marine plants.
The construction of land section of the outfall is similar to typical
pipe laying work with excavation and installation of shoring, bedding pipe
laying, back filling and construction of chambers.
2.6
Operation of the Project
2.6.1
Operational activities, on completion of the
Project, would comprise essentially the operation of the new sewage outfall,
which will replace and upgrade the existing Wan Chai East sewage outfall.
2.7.1
The
construction works of the sewage outfall are anticipated to commence on site in
late 2009, with completion by 2011.
A construction programme is presented in Appendix 2.5 for reference.
2.8
Related Projects
2.8.1
The
following projects are related to the DP5:
(i)
Civil Engineering and
Development Department's CRIII project, comprising reclamation along the
Central waterfront for transport infrastructure needs (including CWB and NIL)
and basic land use requirements. A section of CWB tunnel will also be
constructed under CRIII project.
Construction will take place from February 2003 to September 2012.
(ii)
Trade Development Council’s
Atrium Link Extension project, comprising a link bridge spanning across the
water channel between the Hong Kong Convention and Exhibition Centre (HKCEC)
Phase I and HKCEC Extension.
Construction will take place from May 2006 to March 2009.