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The Civil Engineering Department (CED) manages a comprehensive slope
safety system, which has brought about a substantial improvement in the
safety of slopes in Hong Kong. This has been achieved by improving slope
safety standards and technology, ensuring the safety of new slopes, improving
the safety of existing slopes, and providing public warnings, information,
education and community advisory services on slope safety.
The department audits the adequacy of the design and
construction of all geotechnical works by the private sector, public authorities
and government departments to ensure their long-term safety. In 2003,
it audited 13 666 geotechnical design proposals and inspected
2 890 active construction sites.
The department maintains a continuing Landslip Preventive
Measures (LPM) Programme to rectify the safety of existing slopes. In
2003, a total of about $920 million was spent on the LPM Programme. Upgrading
works were completed on 260 government slopes, and all were landscaped
to blend them with the surrounding environment. In addition, safety screening
was completed on 320 private slopes.
The department inspects hillside squatter villages
to identify huts vulnerable to landslides, recommends rehousing of the
affected squatters and advises the occupants to seek safe shelter during
heavy rain. In 2003, it inspected about 70 squatter villages.
With the availability of the Slope Maintenance Responsibility
Information System on the Internet, members of the public can have ready
access to information on slopes under their responsibility. Other slope-related
information is also available in the Slope Information System. A bilingual
version of the system has been uploaded to the Internet at the CED's Hong
Kong Slope Safety website. The website has become an important source
of reference for the public in obtaining slope-related information.
The Catalogue of Slopes has been made even more comprehensive.
The department has done this by systematically examining the latest topographic
plans and using aerial photograph interpretation techniques in order to
identify and register slopes which meet the registration criteria but
have not been included in the catalogue. The number of registered slopes
in the catalogue has subsequently increased from 54 000 to
57 000.
In sustaining public awareness of slope safety, the
department promotes and disseminates slope safety and slope maintenance
messages to the public, and organises slope safety talks at schools and
roving exhibitions in the community. In addition, a major exhibition will
be held in the Central Library in April 2004 to show the history of landslide
disasters in Hong Kong. A pamphlet on Maintenance of Buried Services
Affecting Slopes is being prepared to remind slope owners to inspect
and maintain underground water-carrying services. As part of efforts to
improve the living environment, an open competition for the 'Best Landscaped
Slope' was launched in June to encourage slope owners to maintain and
beautify their slopes. The response was excellent. |
The department's Community Advisory Unit provides
useful advice to private slope owners to help them maintain and improve
the condition and appearance of their slopes. In order to assist private
slope owners to discharge their slope maintenance responsibility, a simple
guide to 'Dangerous Hillside Orders' has been published to provide a step
by step approach to undertaking the requirements of a Dangerous Hillside
Order (an order issued under the Buildings Ordinance) promptly and effectively.
The Slope Maintenance Audit Section helps maintenance
departments to improve their performance in discharging their slope maintenance
responsibilities. Audits of government slope works indicate a continuous
improvement in the overall state of maintenance.
The department maintains a 24-hour year-round emergency
service to provide geotechnical advice to government departments on actions
to be taken to protect the public against landslide danger. The computerised
information system and telecommunication facilities have been upgraded
to enhance efficiency in handling landslide information and emergency
calls.
The department conducts various studies to improve
the knowledge and methodology of dealing with natural terrain landslide
hazards. It has developed techniques in dating natural terrain landslides,
assessing the mobility of landslide debris and applying Geographic Information
System technology to hazard studies. Natural terrain hazard mitigation
works are being arranged for five sites in developed areas, while studies
are being carried out in respect of four other sites.
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During the year, the department continued to
produce geotechnical guidance documents to disseminate new technological
development findings and improved design and construction practice.
In particular, the third edition of the Guide to Slope Maintenance
and a revised Layman's Guide to Slope Maintenance were
published. Guidance on new vegetation mixes and new planting techniques
for greening slopes was also given. |
The Geotechnical Information Unit in the Civil Engineering
Library houses the largest collection of geotechnical data in Hong Kong.
The library is open to the public, and served more than 26 500
users during 2003.
The department provides specialist geotechnical services
to government departments, including the provision of ad hoc geotechnical
advice and conducting feasibility studies, detailed investigations, design
and construction supervision for a wide range of public works projects.
The projects handled by the department during the year included site formation
works at Kong Sin Wan Tsuen, Pok Fu Lam; slope upgrading works at the
former Victoria Barracks, Kennedy Road; site formation works for the Yam
O Tuk Fresh Water Service Reservoir on Lantau Island, and the Ping Che
Fresh Water Service Reservoir in Fanling; geotechnical works for the drainage
project at San Tin; and geotechnical works for Stage III of the Shenzhen
River Regulation Project. In addition, the department also provides construction
material testing and ground investigation services to support public works
projects. The testing service is provided by the Public Works Laboratories.
During the year, some 880 000 tests were carried out, and
20 000 metres of soil and rock were drilled.
The department enforces legislation relating to mining, quarrying and
explosives, and administers quarrying contracts. It processes applications
for the manufacture, storage, conveyance and use of explosives, and inspects
stone quarries, blasting sites and explosives stores.
Hong Kong consumed 16.3 million tonnes of aggregates
and other rock products in 2003. About 50 per cent of its demand for aggregates
and rock products was met locally, with the balance imported from the
Mainland.
One quarrying contract and two quarry rehabilitation
contracts were in force during the year. The rehabilitation contracts
require the operators to rehabilitate the quarries within a specified
period, in return for the granting of rights to process and sell surplus
rock excavated during the course of the works. The rehabilitation works
involve recontouring and extensive planting to blend the quarries with
the surrounding hillsides.
The department manages two government explosives depots
(one at Kau Shat Wan on Lantau Island and the other at Piper's Hill, Sha
Tin) which provide bulk storage facilities for imported explosives. It
also undertakes the delivery of explosives from the depots to blasting
sites and issues shotfirer certificates. About 2 100 tonnes of explosives
were consumed in 2003, being used mostly for quarrying and site formation
works.
The department also provides technical support to
the Home Affairs Bureau and the Marine Department in assessing applications
for fireworks displays.
The Marine Fill Committee (MFC) is responsible for identifying and managing
the supply of marine fill resources for development projects, and for
managing disposal facilities for dredged and excavated sediment. The Public
Fill Committee (PFC) has the duty to manage construction and demolition
(C&D) materials and utilisation of land-based fill reserves. Both
committees are responsible to the Secretary for the Environment, Transport
and Works.
About 10.9 million cubic metres of C&D materials
were generated by local construction activities in 2003. Of this, about
9.6 million cubic metres of inert materials were re-used as fill in public
filling areas including Tseung Kwan O Area 137, Tuen Mun Area 38, North
Tsing Yi and Penny's Bay, or stockpiled at the fill banks in Tuen Mun
Area 38 and Tseung Kan O Area 137.
The PFC explores ways to minimise the generation of
C&D materials and reduce their disposal at landfills. The construction
industry is encouraged to adopt construction methods and materials that
reduce the generation of C&D materials at source. The temporary recycling
facility at Tuen Mun Area 38 recycles suitable C&D materials into
aggregates for re-use. In 2003, the recycling facility produced about
0.2 million tonnes of recycled aggregates for use in government projects.
The MFC maintains a Fill Management Database on fill
requirements, mud disposal and surplus excavated materials from major
public and private projects. Its purpose is to help the construction industry
coordinate sources of fill materials and make the best use of surplus
materials. All project data is available at the CED's home page.
The department manages mud disposal facilities. In
2003, about seven million cubic metres of uncontaminated mud and 0.5 million
cubic metres of contaminated mud were generated from various works projects
and maintenance works on navigational channels in the harbour. Uncontaminated
mud was disposed of at open sea floor disposal grounds or exhausted marine
sand borrow pits. Contaminated mud was placed in specially selected and
closely monitored exhausted sand borrow pits, which were then capped with
clean mud on completion of filling to isolate the contaminants from the
environment. The use of exhausted sand borrow pits for mud disposal is
preferred as it has the dual benefits of providing much needed disposal
capacity and restoring the seabed to its natural profile and state.
In connection with the management of Hong Kong's fill
resources and mud disposal capacity, the department, on behalf of the
MFC, continues to undertake a series of geotechnical, environmental and
ecological studies and monitoring to examine the effect of the dredging
and disposal activities, and to investigate possible ways to avoid or
minimise the impact on the marine environment.
Coastal engineering projects may affect the flow of water, sediment transport
and wave activity in the harbour. The department employs sophisticated
computer hydraulic models to analyse the likely effects of proposed schemes,
both during and after the construction phases, to ensure that their impacts
are minimised to within acceptable limits. The models are used for reclamation
layout planning, design of marine structures, waterway studies and assessment
of future maintenance dredging requirements. A digital tidal stream atlas
and a wave atlas were also developed by the department in 2001 to provide
average tidal and extreme wave information. These atlases are being updated
to reflect the latest shoreline and seabed profiles and to enhance the
accuracy of the information. |
