hkie seminar

HKIE SEMINAR
CONTROL OF WATER POLLUTION AT
JORDAN VALLEY BOX CULVERT
Speakers:
Gabriel Woo – Senior Engineer, DSD
Kelvin Lau – Director, B&V
渠務署
Drainage Services Department
HKIE SEMINAR
• BACKGROUND
• INTERCEPTION OF DRY WEATHER FLOW
• DESIGN CHALLENGES
• DWFI SCHEME
• PROPOSED CONSTRUCTION WORKS
• CONSTRUCTION CHALLENGES
• SUSTAINABILITY AND ENVIRONMENTAL
CONSIDERATIONS
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BACKGROUND
HKIE SEMINAR
Drainage
Catchment
Site Boundary
7-cell Jordan Valley
Box Culvert (JVBC)
Existing Trunk
Sewer
Drainage Catchment
Existing Trunk Sewer
JVBC
Site Boundary
Jordan Valley Channel
Jordan Valley Channel
Cruise Terminal Site
LEGEND:
Kwun Tong
Preliminary
Treatment Works
(PTW)
Kwun Tong PTW
• Flow in JVBC polluted due to expedient connections and non-point pollution sources
• Water quality problem in water receiving body and associated odour problems
• Dry weather flow interception (DWFI) system proposed to intercept the polluted flow
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HKIE SEMINAR
BACKGROUND
Jordan Valley Box Culvert
Site Boundary
Mega Box
4.12 m
7-cell Jordan Valley Box Culvert
3.8 m
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BACKGROUND
Outlet of Jordan Valley Box Culvert (JVBC)
• 7-cell box culvert (each 4 m wide)
JVBC
Project Area
Polluted Dry Weather Flow from JVBC
• Design DWF rate = 0.5m3/s
November 4, 2009
Page - 5
BACKGROUND
HKIE SEMINAR
Aims at Improving the water quality of Kai Tak Approach Channel
Milestones





Project Commencement : 30 September 2008
Design Completion : December 2009
Works Contract Commencement : 22 December 2010
Anticipated Commencement of Interception : Mid 2013
Anticipated Contract Completion : 21 May 2014
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INTERCEPTION OF POLLUTED FLOW
Description
Total interception of DWF at
downstream of JVBC
HKIE SEMINAR
Details
A single DWFI compound at downstream of
JVBC to intercept all DWF flowing through the
compound
Considerations:
(1) Technical complexity – No need to modify balancing holes at upstream
(2) Land requirement – Site already reserved for DSD desilting compound
(3) Cost – Less estimated construction cost
(4) Effectiveness – DWF completely intercepted at downstream
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HKIE SEMINAR
DESIGN CHALLENGES
Limited
Land
Design
DWF
Rate
MAINTAIN
Tidal
DESIGN
STORMWATER FLOW Influence
Automatic
Interception
Control
Soil
Tide level 0 to +2.7 mPD
- 0.70 mPD
Tidal Water
Existing JVBC
- 0.69 mPD
Soil
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DWFI SCHEME
HKIE SEMINAR
Wet Weather (WW) Mode:
During wet weather or heavy rainfall in dry seasons, the tidal barrier will
open automatically to allow discharge of stormwater at the JVBC and no
DWF will be intercepted under these conditions.
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DWFI SCHEME
HKIE SEMINAR
Residual Water Discharge (RWD) Mode:
During dry weather, the tidal barrier will be closed. The residual water
trapped at the upstream of the tidal barrier will be pumped to the
downstream of the JVBC via the pumps at the pumping station.
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DWFI SCHEME
HKIE SEMINAR
Dry Weather Flow (DWF) Mode:
When the residual water is sufficiently drawn down, the pumps at the
pumping station will be switched to pump the DWF from the JVBC to the
adjacent Kai Fuk Road Trunk Sewer.
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DWFI SCHEME
HKIE SEMINAR
Future Desilting Operations
The silt accumulated inside the JVBC will be removed from the DWFI
compound and subsequently disposed off site.
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PROPOSED CONSTRUCTION WORKS
HKIE SEMINAR
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PROPOSED CONSTRUCTION WORKS
HKIE SEMINAR
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CONSTRUCTION CHALLENGES
HKIE SEMINAR
Maintain
Stormwater
Flow
Unexpected
Underground
Utilities
Construction
Tidal
Influence
Limited
Time
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CONSTRUCTION CHALLENGES
HKIE SEMINAR
To Maintain Stormwater Flow
Diversion Scheme – Stage 1
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CONSTRUCTION CHALLENGES
HKIE SEMINAR
To Maintain Stormwater Flow
Diversion Scheme – Stage 2
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CONSTRUCTION CHALLENGES
HKIE SEMINAR
To Maintain Stormwater Flow
Diversion Scheme – Stage 2
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CONSTRUCTION CHALLENGES
HKIE SEMINAR
Site Flooding due to Extreme High Tide
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CONSTRUCTION CHALLENGES
HKIE SEMINAR
Limited Construction Period
The construction time is limited due to:
1. Construction inside JVBC can only be carried out during dry
seasons, which start from November to March inclusive; and
2. Heavy machinery, e.g. crane, cannot be used at the same time
due to limit working area.
Solutions:
1. Extending working hours approved by EPD
2. Better portion construction arrangement
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SUSTAINABILITY AND ENVIRONMENTAL
CONSIDERATIONS
HKIE SEMINAR
Environmental and Sustainability Design
Landscape and energy efficiency measures will be included in the
future facilities:
1. All lands at-grade to be planted with standard trees;
2. Vertical greening along boundary fences and external walls;
3. Green roofs with ground covers;
4. Skylights at the structures’ roofs;
5. LED lighting to be used in the structures; and
6. Photovoltaic modules on the roofs.
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PROPOSED CONSTRUCTION WORKS
HKIE SEMINAR
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SUSTAINABILITY AND ENVIRONMENTAL
CONSIDERATIONS
Temporary Holding Nursery and Permanent Tree Location
14 trees transplanted to Siu Ho Wan
Sewage Treatment Works
Tree No. T9 Original Location
Trees Felled
Proposed Desilting Compound
Proposed Pumping Station
Transplantation Route
T9
Final Location
Location of
Temporary
Nursery
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SUSTAINABILITY AND ENVIRONMENTAL
CONSIDERATIONS
HKIE SEMINAR
Preservation of Existing Trees –
ENGINEER’S DESIGN for transplanting T9
• Melia azedarach
• Well-balanced and very good form
• 8 m tall with a crown dia of 8 m
• Structural inverted triangular steel
container (6.4 m x 6.4 m x 3 m deep)
• No pruning to its branches and roots
• Tree together with the temporary rootball
container weigh 200 tonnes
• 400-tonne crawler crane and two 17024
tonne trailers to be used
SUSTAINABILITY AND ENVIRONMENTAL
CONSIDERATIONS
HKIE SEMINAR
Preservation of Existing Trees - DESIGN
2014
Final Position in
Project Boundary
Original
Location
Location of
Temporary Nursery
April 2011
SUSTAINABILITY AND ENVIRONMENTAL
CONSIDERATIONS
Preservation of Existing Trees - CONSTRUCTION
Engineering Works for Transplantation
and Lifting Process
Temporary Works for Tree Pot
SUSTAINABILITY AND ENVIRONMENTAL
CONSIDERATIONS
Preservation of Existing Trees - CONSTRUCTION
Engineering Works for Transplantation
and Lifting Process
Temporary Works for Tree Pot
SUSTAINABILITY AND ENVIRONMENTAL
CONSIDERATIONS
Preservation of Existing Trees - CONSTRUCTION
SUSTAINABILITY AND ENVIRONMENTAL
CONSIDERATIONS
Preservation of Existing Trees - CONSTRUCTION
Engineering Works for Transplantation and
Lifting Process
Trial Lifting for Measurement of Total Weight
SUSTAINABILITY AND ENVIRONMENTAL
CONSIDERATIONS
HKIE SEMINAR
Preservation of Existing Trees - CONSTRUCTION
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SUSTAINABILITY AND ENVIRONMENTAL
CONSIDERATIONS
HKIE SEMINAR
Preservation of Existing Trees - CONSTRUCTION
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SUSTAINABILITY AND ENVIRONMENTAL
CONSIDERATIONS
HKIE SEMINAR
Preservation of Existing Trees - CONSTRUCTION
Ming Pao’s Press
Report after site
visit on 11 Aug
2011
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HKIE SEMINAR
THANK YOU
渠務署
Drainage Services Department