6.1.2
The operation of the proposed Roads
D1, D8 and D10 and extended Road P2 will generate wastes associated with
littering and road maintenance activities, and the amount is expected to be
minimal. The potential environmental
impacts arising from the handling and disposal of this small amount of wastes
is anticipated to be negligible and therefore have not been evaluated further
in this report.
6.1.3
The construction of Roads D1, D8 and
D10 and extended Road P2 will mainly involve earthworks excavation and road
pavement, except in the case of Road D10 where the foundation of the section
across the Eastern Drainage Channel will require bored piling. The main issues
having waste management implications during construction are (i) workforce
wastes, (ii) chemical wastes, and (iii) construction and demolition (C&D)
material.
Waste Management
Construction and Demolition (C&D) Material
6.2.7
The following circulars also relate to
C&D material management :
§
WBTC
No. 1/96, Wet Soil in Public Dumps;
§
WBTC
Nos. 5/99 & 5/99A, Trip-ticket System for Disposal of Construction and
Demolition Material;
§
WBTC
No. 18/99, Particular Specification Clause for Vehicles Carrying Dusty
Materials:
§
WBTC
No. 19/99, Metallic Site Hoardings and Signboards;
§
WBTC
Nos. 25/99, 25/99A & 25/99B, Incorporation of Information on Construction
and Demolition Material Management in Public Works Subcommittee Papers;
§
WBTC
No. 12/2000, Fill Management; and
§
WBTC
No. 29/2000, Waste Management Plan.
Chemical Waste
6.3.1
The criteria for evaluating the
potential construction waste management implications are set out in Annex 7 of
the EIAO-TM. The methods for assessing
potential waste management impacts during construction follow those presented
in Annex 15 of the EIAO-TM and include the following:
§
estimation
of the types and quantities of the wastes generated;
§
assessment
of potential impacts from the management of solid waste with respect to potential
hazards, air and odour emissions, noise, wastewater discharges and transport;
and
§
impacts
on the capacity of waste collection, transfer and disposal facilities.
WORKFORCE WASTES
Chemical Wastes
·
toxic
effects to workers;
·
adverse
impacts on water quality from spills and adverse impacts on marine biota; and
·
fire
hazards.
6.4.6
It is difficult to quantify the amount
of chemical waste which will arise from the construction activities since it
will be highly dependent on the Contractor’s on-site maintenance requirements
and the number of plant utilised.
However, it is anticipated that the quantity of chemical waste, such as
lubricating oil and solvent produced from plant maintenance, will be small and
in the order of a few hundred litres per month. The amount of chemical waste
expected to be generated will be quantified in the site Waste Management Plan
to be prepared by the Contractor.
Construction and Demolition (C&D) Material
§
wood
from formwork and falsework;
§
materials
packaging and equipment wrappings;
§
unusable
/ surplus concrete / grouting mixes; and
§
damaged
or contaminated surplus construction materials.
6.4.8
If not managed properly, the storage,
handling, transport and disposal of C&D material have the potential to
create visual, water, dust and traffic impacts. C&D material should be
sorted on-site into inert materials (public fill) which should be re-used
on-site as far as possible or disposed of to public filling facility, and
C&D waste which may need to be disposed of to landfill. Marine pollution
from this waste should not be permitted because of the potential to cause water
pollution and indirect impacts on marine biota. Mitigation measures should include provision of a collection area
where waste can be stored and loaded prior to removal from the site. The volume of surplus construction material
generated will be dependent on the Contractor’s operating procedure and
practices and cannot be quantified at this early stage
as no detailed construction programme is currently available for the
Project. However, with respect to the
nature of construction activities, it is anticipated that the quantity will be
small.
6.4.9
Given that the construction works for
the proposed roads are on existing and new reclamation, there will be minimal
generation of C&D waste as no existing facilities or structures would
require demolition. The major type of C&D material generated will be excavated
material from the foundation construction works for Roads D1 and D10, as
discussed below.
6.4.10
It is estimated that approximately
10,000 m3 of excavated material will be generated from the
foundation construction of Roads D1 and D10, and a total of 50,000 m3
of fill materials will be required for the construction of road embankments of
the three Roads D1, D8 and D10 (see Table 6.1). Based on the preliminary
estimate that about 10% of the excavated material will be unsuitable to be
reused on-site, the quantity of excavated materials to be disposed off-site
will be small (about 1,000 m3).
A detailed construction programme is currently not available for the
roads, and therefore the timing for the generation of excavated material will
be given in the site Waste Management Plan.
The tentative timing of foundation works for Road D10 is indicated in
Figure 2.4
6.4.11
Excavated material from Road D10
requiring off-site disposal would comprise marine mud and alluvium. The excavated material from Road D1
requiring off-site disposal would comprise reclamation fill (i.e. public fill)
and would be suitable for disposal to a public filling facility. It is
considered that the additional traffic arising from transporting this amount of
excavated materials will not be adverse. In order to reduce the impacts from
off-site transportation of excavated materials, the reclamation fill material should
be reused on-site as fill materials for site formation and construction of road
embankment as far as possible.
Table 6.1 Estimated
Earthworks Quantities for the Construction of Roads D1, D8 & D10
|
Road
Description
|
Excavation
Volume
(m3)
|
Fill volume
(m3)
|
Disposal
volume
(m3
)
|
|
Road D1 including
D1/D10 roundabout
|
7,500
|
32,000
|
750 (public fill)
|
|
Road D8
|
-
|
8,000
|
-
|
|
Road D10
|
2,500
|
10,000
|
250 (C&D waste)
|
|
Extended Road P2
|
|
85,000
|
|
|
Total
|
10,000
|
|
1,000
|
6.4.12
The agreed alignment of Road D10 falls
inside the boundary of the TKO Stage 1 landfill at Area 77, although the
proposed pile locations will not encroach on the waste boundary at Area
77. An issue specific for the section
of Road D10 adjacent to Area 77 is the possibility that the excavated material
may be contaminated by leachate seepage from the TKO Stage 1 landfill. It is therefore recommended that the
excavated material from the foundation construction (approximately 250m3)
be considered as contaminated material and disposed off-site to existing operating
landfill. It is anticipated that the
excavated material from the Road D10 construction works not adjacent to Area 77
will be suitable for reuse on-site.
6.4.13
EPD have advised that marine mud
excavated from bored piling construction for Road D10 should be disposed of by
marine dumping in order to conserve limited and valuable landfill void
space. For marine disposal of the
excavated mud, the requirements of WBTC
No. 3/2000 ‘Management of Dredged/Excavated Sediment’ should be followed.
Site investigation works would be carried out at the detailed design stage in
the area of proposed pile foundations to determine the material type. In the unlikely event that refuse is found
in the area of piling, possible disposal methods of the mixed refuse/marine mud
material would be examined. As EPD have
advised that refuse is generally not allowed to be disposed of at marine
dumping ground, the mixed material is likely to require dewatering prior to
disposal to landfill.
GOOD Site PRACTICE
·
Nomination
of an approved person, such as a site manager, to be responsible for the
implementation of good site practices, arranging for collection and effective
disposal to an appropriate facility, of all wastes generated at the site
·
Training
of site personnel in proper waste management and chemical handling procedures
·
The
reuse and recycling of materials wherever possible
·
Plan
and stock construction materials carefully to minimise amount of waste
generated and avoid unnecessary generation of waste
·
Provision
of sufficient waste disposal points and regular collection for disposal
·
Provision
of an enclosed collection point for storage and containment
·
Separation
of chemical wastes for special handling and appropriate treatment at the
Chemical Waste Treatment Facility
·
Regular
cleaning and maintenance programme for drainage systems, sumps and oil
interceptors.
·
Develop
procedures such as a ticketing system to facilitate tracking of loads and to
ensure that illegal disposal of waste does not occur.
·
Maintain
records of the quantities of wastes generated, recycled and disposed.
General Site Wastes
Workforce Wastes
Chemical Wastes
6.5.6
Any service shop and minor maintenance
facilities shall be located on hard standings within a bunded area, and sumps
and oil interceptors shall be provided.
Maintenance of vehicles and equipment involving activities with
potential for leakages and spillage shall only be undertaken with the areas
appropriately equipped to control these discharges.
Construction and Demolition (C&D) Material
6.5.10
In order to monitor the disposal of
C&D waste at landfills and to control fly tipping, a trip-ticket system
should be included as one of the contractual requirements and implemented by an
Environmental Team undertaking the Environmental Monitoring and Audit work. An Independent Environmental Checker should
be responsible for auditing the results of the system.
6.5.11
It is recommended that, where
practicable, public fill be used instead of imported general fill for
earthfilling related activities for the Project. The imported public fill should be obtained off-site from other
public fill stockpile areas. The use of
suitable recycled C&D materials in the road formation contract should be
considered at the detailed design stage if recycling facilities/sources are
available. This would be in accordance
with WBTC No. 31/2000, ‘Specification
Allowing the Use of Recycled Inert Construction and Demolition Material.’ There is currently a sorting facility at
Area 137. CED have plans to upgrade
this facility to a recycling plant however this proposal is very preliminary.
C&D material from road d10 foundation construction
adjacent to area 77
6.5.12
As a precautionary measure trial pits
will be dug during the construction of the piers for Road D10 to ensure that
there is no waste material at the piling foundation. It is recommended that the excavated material from the foundation
construction be considered as contaminated material and disposed off-site to
existing operating landfill. The
existing seawall adjacent to the Road D10 alignment is a rubble mound seawall and
will allow some movement of sea water.
The excavated material is likely to be of high moisture content and
therefore dewatering may be required before disposal of the material to
landfill (so as to meet the permitted waste type requirements on water content). Marine mud excavated from the bored pile
foundation works for Road D10 will require marine disposal in order to conserve
landfill void space.
6.6.1
With the implementation of the
recommended mitigation measures for the handling, transportation and disposal
of the identified waste arisings, no residual impact is anticipated during the
construction of the proposed road developments.
6.7.1
Wastes generated by the construction
activities are likely to include C&D materials, workforce waste and
chemical waste. Provided that these
identified waste arisings are handled, transported and disposed of using
approved methods and that the recommended good site practices are strictly
followed, adverse environmental impacts are not anticipated. The recommended mitigation measures shall
form the basis of the site Waste Management Plan to be developed by the
Contractor at the commencement of the construction phase.
6.7.2
Table 6.2 provides a summary of the
various waste types likely to be generated during the construction phase,
together with the recommended handling and disposal methods.
Table
6.2 Summary of Waste Handling
Procedures and Disposal Routes
|
Waste Type
|
Handling
|
Disposal
|
|
Construction
& Demolition Material
|
Where possible should be re-used on-site
If off-site disposal required, separate into:
·
Public fill (e.g. concrete, rubble, earth)
·
C&D waste for re-use and/or recycling (e.g. wood,
plastic, steel and other metals)
·
C&D waste which cannot be re-used and/or recycled
|
On-site as fill materials for site formation/road
embankment
|
|
Public filling facillity or reclamation
To be determined at a later stage
Landfill
|
|
|
Landfill
|
|
·
Excavated Mud from Road D10 foundation works within
Eastern Drainage Channel: Non-displacement type bored piling to drive
temporary steel casing through the soft mud prior to excavation of the
material within the casing
|
Marine disposal
|
|
Maintenance
and Chemical Wastes
|
Recycle on-site or by licensed companies
Stored on-site within suitably designed containers
|
By licenced contractor to Chemical Waste Treatment
Facility
|
|
Workforce
Wastes
|
Provide on-site refuse collection facilities
|
Landfill, collection by
private hygiene company
|