|
Domain |
Explanation |
|
Speaker |
- Mr John Wei is currently the Chief Civil Engineer (from 1985 to present) and Head of Civil Engineering Department at HDB. He is overall in charge of the HDB's reclamation and infrastructure programmes. These involve numerous foundation projects and infrastructure projects (drainage, sewerage, bridges, roads, etc). He has overseen a total of 17 reclamation projects with a total project cost amounting to over S$2 billion as well as foundation and infrastructure projects amounting to some S$6 billion. He is also concurrently the Director of CESMA, a wholly owned subsidiary of HDB involved in consultancy works for local and overseas projects.
|
|
Abstract |
- Land reclamation projects in Singapore have been going on for the past 4 decades. HDB pioneered this programme in the early 1960s with the objective of creating more land in land-scarce Singapore to cater to the needs of various developments such as housing, industry, infrastructure and recreation. To date HDB has reclaimed some 33 sq km (5% of Singapore's total land area) and will, for the foreseeable future, continue to reclaim more land. This presentation will provide an overview of HDB's reclamation programme, with highlights on the planning, design & construction features of various major schemes. The presentation will cover the following topics:
- 1 Introduction
2 Past reclamation projects
3 Impact of HDB reclamation
4 On-going reclamation projects
5 Suitability of site
6 Planning & implementation process
7 Construction methods
8 Typical cross-sections of seawall
9 Future trends
10 Future reclamation projects
|
|
Introduction |
- Main three land reclaimer in Singapore:
- HDB
- JTC
- PSA
|
|
Past reclamation |
- Kallang Basin
- East Coast
- Marina Bay/Tanjong Rhu
- North East Coast (Punggol)
- West Coast: park, wholesale market
- Pasir Ris
- Woodlands: checkpoint
- Tuas: 2nd-link whole land – CIQ (Checkpoint, Immigration & Quarantine)
|
|
Ongoing HDB reclamation |
- Southern Islands: St. John etc.
- Linking-up: to form cluster of islands for future lifestyle
- Causeways & infra-links: either filled to seabed or VLFS
- Services: cables, conduits, water, sanitary
- Design modeled: Southern France: yachting & transport
- Pulau Tekong:
- Phases: recent – immediate reclamation with good fill materials
- Later phases: first in-filled with useless materials especially construction waste materials
- Requires: R&DD into soft fill problems, settlement, strength & slope stability
|
|
Impacts |
- Geotechnical considerations:
- Depth of seabed
- Seabed soil conditions: good – stiff; soft – poor; used up good sites
- Fill materials
- Settlement & strength: strains & stresses
- Slope stability
- Reclamation cost: $25 - $150/m2
- Fill materials derived:
- Cut hills from: Bedok Town, Tampines, Bedok Reservoir (silky sand – valuable)
- New land use:
- Marine Parade Estate
- East Coast Condominium
- ECP
- Beach, Park, Golf courses, Customs, Refuse dumping, New Towns
|
|
Reclamation project management |
- Involves two processes:
- Planning process
- Implementation process
|
|
Planning process |
- Time: 2years
- Works:
- Feasibility studies
- Preliminary layout design
- Preliminary investigations:
- Hydrographic survey:
- Soil investigation:
- Consultation with authorities
- Submission:
- MPC: approval
- DPC: funds for development
- Cabinet
- Parliament: in gazette
|
|
Implementation process |
- Time: 5-6years
- Site investigation
- Drawings
- Proposal submission
- Preparations:
- Open tender: HDB as agent for government & as project managers in design; others tender, execute with their expertise & equipment
- Call tender
- Evaluation: how & compare
- Construction phase
- Handovers: of reclaimed land
- From contractors to HDB
- From HDB to government: government land (proclamation survey)
|
|
Geotechnical aspects |
- Site suitability:
- Location:
- Port limits
- PSA anchorage areas: parking lots for ships
- Channels of movement: fairways, navigational channels à pattern of currents & congestion
- Land use:
- Housing, commercial, industrial, recreational, treatment
- Fill material availability:
- Sea sand (>70% sand, 30% fines) for sand key & fill
- Seawalls’ stones: protect coastlines & prevent rapid erosion
- Sources, supplies, economics
- Seabed condition:
- Shallow?
- Poor soil?
- Seabed bathymetry
- Best areas are reclaimed, poorer areas in future
- Coastal & environmental development:
- Hydrodynamics:
- Local modeling & calibration
- Maths & 3-D: accurate
- Current speed & direction
- Wave height
- Sediment transport effects:
- Sedimentation
- Scouring
- Water quality:
- Land impedes current flow
- Stagnant water: bad smell
- Observe: mangroves, corals, marine life
- Developmental constraints:
- Height: building lower near airports
- Proximity to existing infrastructure: roads, farms, ports, dams
- Preservation: mangrove, natural
- Construction methods:
- Location of cut site & sand winning areas (from constant sedimentation)
- Economics
- Availability of equipment & plants: HDB may alter plans to accommodate tools available for lower costs, etc.
- Changes in technologies
- Others:
- Rainbowing: from trailer suction dredger shooting sand into sea
- Direct hydraulic pumping
- Sand compaction pile method
- Embankments:
- Revetment:
- Slope stability problem solved
- Slope 3:1
- Sand piles: increase shear strength of seabed
- Geo-fabric layering: filtering + stones + cement mortar to protect slope
- Seawall:
- Vertical concrete ‘L’-shaped blocks assembled along the coastline
- Coping wall
- With cladding on the external side: can be replaced & maintained without removing the seawalls behind
|
|
Trends |
- More reclamations
- Deeper waters, deeper depth, poor seabed soil conditions, variable currents hydroflow
- Use of dredged materials: conversion into useful materials
- New technologies & innovation
|
|
Q&A |
- Fill supplies:
- Waste materials: R&D into fill suitability & conversion into useful materials
- Steel
- Dredge: deepening of channels, endless sedimentation by rivers (goldmine)
- Economic aspects: sale by blackmail, held to ransom
- VLFS: save fill, allow flows (planned reclamation has discrete holes to pass water), aesthetic & portable
- Reclamation: mechanics tolerance
- Stabilizing system: esp. @ land areas of priority (like roads, housing), not recreations à use of dynamic compaction & vertical drain
- Piles:
- Slightly higher costs at greater depth over reclaimed land
- Costs of others outweight piles: Tham
|