7
Waste Management Assessment
This section identifies the potential waste arising
from the construction and operation of the potential wind farm and assesses the
environmental impacts associated with waste handling and disposal. The main issues are:
·
Management
of dredged marine sediment;
·
Handling
and disposal of C & D materials ([1]) arising from the construction works; and
·
Potential
leakage of chemical wastes from plant, equipment, vessels and turbines.
Waste avoidance, minimisation, reuse and recycling,
storage, collection, transport and disposal schemes have been examined and
appropriate measures for waste reduction and management have been
proposed.
7.2
Legislation
Requirements and Evaluation Criteria
The following discussion on legislative requirements
and evaluation criteria applies to both the construction and operational phases
of the wind farm. The criteria and
guidelines for evaluating potential waste management implications are laid out
in Annexes 7 and 15 of the EIAO-TM under
the EIAO (Cap 499). The following legislation covers, or has
some bearing upon the handling, treatment and disposal of the wastes generated
from the construction and operation of the wind farm.
·
Waste Disposal Ordinance (Cap 354);
·
Land (Miscellaneous Provisions) Ordinance
(Cap 28);
·
ETWBTC(G) No. 2/93, Public Dumps. Works
Branch,
·
Waste Disposal (Chemical Waste) (General) Regulation
(Cap 354C);
·
Public Health and Municipal Services
Ordinance (Cap 132) - Public Cleansing and Prevention of Nuisances Regulation;
and
·
Dumping at Sea Ordinance (Cap 466).
7.2.1
Waste Disposal Ordinance (Cap 354)
The Waste
Disposal Ordinance (WDO) prohibits the unauthorised disposal of wastes,
with waste defined as any substance or article, which is abandoned. Construction waste is not directly
defined in the WDO but is considered
to fall within the category of ‘trade waste’. Trade waste is defined as waste from any
trade, manufacturer or business or any wasted building, or civil engineering
materials, but does not include animal waste.
Under the WDO,
wastes can only be disposed of at a licensed site. The WDO
provides for the issuing of licences for the collection and transport of
wastes. Licences are not, however,
currently issued for the collection and transport of construction waste or
trade waste.
The Waste
Disposal (Charges for Disposal of Construction Waste) Regulation defined
construction waste as any substance, matters or things that is generated from
construction work and abandoned, whether or not it has been processed or
stockpiled before being abandoned.
It does not include any sludge, screening or matter removed in or
generated from any desludging, desilting
or dredging works.
The Construction Waste Disposal Charging Scheme
entered into operation on 1 December 2005. Starting from 1 December 2005, the
main contractor who undertakes construction work under a contract with value of
HK$1 million or above is required to open a billing account solely for the
contract for waste disposal.
Application shall be made within 21 days after the contract is
awarded.
Depending on the percentage of inert materials in the
construction waste, inert construction waste can be disposed of at public fill
reception facilities. However mixed
construction waste can be disposed of at construction waste sorting facilities,
landfills and Outlying Islands Transfer Facilities which have different
disposal costs. The scheme
encourages reducing, reusing and sorting of construction waste such that the
waste producer can reduce their disposal fee. Table
7.1 summarises the government construction waste disposal facilities, types
of waste accepted and disposal cost.
Table 7.1 Government Facilities for Disposal of
C&D Materials
|
Government
Waste Disposal Facilities |
Type of
Construction Waste Accepted |
Charge
(HK$/Tonne) |
|
Public fill reception facilities |
Consisting entirely of inert construction waste |
$27 |
|
Sorting facilities |
Containing more than 50% by weight of inert construction
waste |
$100 |
|
Landfills |
Containing not more than 50% by weight of inert
construction waste |
$125 |
|
Outlying |
Containing any percentage of inert construction waste |
$125 |
7.2.2
Land (Miscellaneous Provisions) Ordinance
(Cap 28)
The inert portion of C&D materials (also called public
fill) may be taken to public fill reception facilities. Public fill reception facilities usually
form part of land reclamation schemes and are operated by the Civil Engineering
and Development Department (CEDD) and others. The Land
(Miscellaneous Provisions) Ordinance requires that individuals or companies
who deliver public fill to the public fill reception facilities to obtain
Dumping Licences. The licences are
issued by CEDD under delegated authority from the Director of Lands.
Individual licences and windscreen stickers are
issued for each vehicle involved.
Under the licence conditions, public fill reception facilities will only
accept earth, soil, sand, rubble, brick, tile, rock, boulder, concrete,
asphalt, masonry or used bentonite. In addition, in accordance with
paragraph 11 of ETWB TCW No. 31/2004 “Trip Ticket System for Disposal of
Construction and Demolition Materials”, the Public Fill Committee will
advise on the acceptance criteria (e.g. no mixing of construction waste,
nominal size of the materials less than 250mm, etc). The material will, however, be free from
marine mud, household refuse, plastic, metal, industrial and chemical wastes,
animal and vegetable matter and any other materials considered unsuitable by
the public fill reception facility supervisor.
7.2.3
ETWBTC(G) No. 2/93, ‘Public Dumps’
The policy for the disposal of C&D material is
documented in the ETWBTC(G) No. 2/93,
‘Public Dumps’.
Construction and demolition materials that are wholly inert, namely
public fill, should not be disposed of to landfill, but taken to public filling
areas, which usually form part of reclamation schemes. The circular requires that dumping
licences be obtained by individuals or companies who deliver public fill to
public filling areas.
Measures have been
introduced under ETWB TCW No. 33/2002, “Management of Construction and
Demolition Material Including Rock” to enhance the management of C&D
material, and to minimize its generation at source. The enhancement measures include: (i) drawing up a Construction and Demolition Material
Management Plan (C&DMMP) at the feasibility study or preliminary design
stage to minimize C&D material generation and encourage proper management
of such material; and (ii) providing the contractor with information from the
C&DMMP in order to facilitate the preparation of the Waste Management Plan
(WMP) and to minimize C&D material generation during construction. Projects generating C&D material
less than 50,000 m3 or importing fill material less than 50,000 m3
are exempt from the C&DMMP. ETWB
TCW No. 19/2005 “Environmental Management on Construction Sites” includes
procedures on waste management requiring contractors to reduce the C&D
material to be disposed of during the course of construction. Under ETWB TCW No. 19/2005, the
contractor is required to prepare and implement an Environmental Management
Plan (EMP) and the WMP becomes part of the EMP.
7.2.4
Waste Disposal (Chemical Waste) (General)
Regulation (Cap 354C)
Chemical waste as defined under the Waste Disposal (Chemical Waste) (General)
Regulation includes any substance being scrap material, or unwanted
substances specified under Schedule 1
of the Regulation, if the specified
substance or chemical occurs in such a form, quantity or concentration so as to
cause pollution or constitute a danger to health or risk of pollution to the
environment.
A person should not produce, or cause to be produced,
chemical wastes without registration with the EPD. Chemical wastes must either be treated
using on-site facility licensed by EPD or be collected by a licensed collector
for off-site treatment at a licensed facility. Under EPD regulations, the waste
producer, collector and disposal facility must sign all relevant parts of a
computerised trip ticket for each consignment of waste. The computerized system is designed to
allow the transfer of wastes to be traced from cradle-to-grave. The EPD Regulation prescribes storage facilities to be provided on site
which include labelling and warning signs.
To reduce the risks of pollution and danger to human health or life, the
waste producer is required to prepare and make available written emergency
procedures for spillage, leakage or accidents arising from the storage of
chemical wastes. They must also
provide their employees with training on such procedures.
7.2.5
Public Health and Municipal Services
Ordinance (Cap 132) - Public Cleansing and Prevention of Nuisances Regulation
This Regulation
provides a further control on the illegal dumping of wastes on unauthorised (unlicensed)
sites.
7.2.6
Dumping at Sea Ordinance (Cap 466)
This Ordinance came
into operation in April 1995 and empowers the Director of Environmental
Protection (DEP) to control the disposal and incineration of substances and
articles at sea for the protection of the marine environment. Under the Ordinance, a permit from the DEP is required for the disposal of
regulated substances within and outside the waters of the Hong Kong SAR. The permit contains terms and conditions
that includes the following specifications:
·
Type
and quantity of substances permitted to be dumped;
·
Location
of the disposal grounds;
·
Requirement
of equipment for monitoring the disposal operations; and
·
Environmental
monitoring requirements.
Management of Dredged/Excavated Sediments for Marine
Disposal
Marine disposal of any dredged/excavated sediment is
subject to control under the Dumping at
Sea Ordinance 1995. Dredged/excavated
sediment destined for marine disposal is classified based on its contaminant
levels with reference to the Chemical Exceedance Levels (CEL), as stipulated in ETWBTC(W) No. 34/2002: Management of Dredged/Excavated Sediment. This Technical Circular includes a set
of sediment quality criteria, as presented in Table 7.2, which includes heavy metals and metalloids, organic
pollutants and a class of contamination level for highly contaminated sediment
not suitable for marine disposal.
Table 7.2 Dredged/Excavated
Sediment Quality Criteria for the Classification under the ETWBTC(W)
No. 34/2002
|
Contaminants |
Lower Chemical Exceedance Level (LCEL) |
Upper Chemical Exceedance Level (UCEL) |
|
Metals (mg kg-1 dry weight) |
||
|
Cd |
1.5 |
4 |
|
Cr |
80 |
160 |
|
Cu |
65 |
110 |
|
Hg |
0.5 |
1 |
|
Ni (a) |
40 |
40 |
|
Pb |
75 |
110 |
|
Silver (Ag) |
1 |
2 |
|
Zinc (Zn) |
200 |
270 |
|
Metalloid
(mg kg-1 dry weight) |
||
|
Arsenic (As) |
12 |
42 |
|
Organic-PAHs (mg
kg-1 dry weight) |
||
|
Low Molecular Weight (LMW) PAHs |
550 |
3,160 |
|
High Molecular Weight (HMW) PAHs |
1,700 |
9,600 |
|
Organic-non-PAHs (mg
kg-1 dry weight) |
||
|
Total PCBs |
23 |
180 |
|
Organometallics
(mgTBT l-1 in interstitial water) |
||
|
Tributyl-tin (a) |
0.15 |
0.15 |
|
Note: (a) The contaminant level is considered to
have exceeded the UCEL if it is greater than the value shown. |
||
In accordance with ETWBTC(W) No. 34/2002, the
sediment is classified into three categories based on its contamination levels:
Category L: Sediment
with all contaminant levels not exceeding the LCEL. The material must be dredged,
transported and disposed of in a manner which reduces the loss of contaminants
either into solution or by re-suspension.
Category M: Any one or more contaminants in the sediment exceeding
the LCEL with none exceeding the UCEL.
The material must be dredged and transported with care, and must be
effectively isolated from the environment upon final disposal unless
appropriate biological tests demonstrate that the material will not adversely
affect the marine environment.
Category H: Any one or more contaminants in the sediment exceeding
the UCEL. The material must be
dredged and transported with great care, and must be effectively isolated from
the environment upon final disposal.
Figure
7.1 summarises the
sediment classification and disposal arrangements. EPD will use the sediment and biological
test results to determine the most appropriate disposal site (e.g., open sea or
confined marine disposal site).
Figure 7.1 Management
Framework for Dredged/Excavated Sediment
|
|
Notes:
1.
Most
open sea disposal sites are multi-user facilities and as a consequence their
management involves a flexibility to accommodate varying and unpredictable
circumstances. Contract documents will include provisions to allow the same
degree of flexibility to divert from one disposal site to another during the
construction period of a contract.
2.
Dedicated
Sites will be monitored to confirm that there is no adverse impact.
3.
For
sediment requiring Type 2 or Type 3 disposal, contract documents will state the
allocation conditions of Marine Fill Committee (MFC) and DEP. At present, East Sha Chau Mud Pits are designated
for confined marine disposal.
4.
If
any sediment suitable for Type 3 disposal (Category H sediment failing the
biological dilution test) is identified, it is the responsibility of the
project proponent, in consultation with DEP, to identify and agree, the most
appropriate treatment and/or disposal arrangement. Such a proposal is likely to
be very site and project specific and therefore cannot be prescribed. This does
not preclude treatment of this sediment to render it suitable for confined marine
disposal.
5.
The
allocation of disposal space may carry a requirement for the project proponent
to arrange for chemical analysis of the sediment sampled from 5% of the vessels
en-route to the disposal site. For Category M and certain Category H sediment,
the chemical tests will be augmented by biological tests. Vessel sampling will
normally entail mixing five samples to form a composite sample from the vessel
and undertaking laboratory tests on this composite sample. All marine disposal
sites will be monitored under the general direction of the CEDD. However,
exceptionally large allocations might require some additional disposal site
monitoring. These will be stipulated at the time of allocation.
6.
Trailer
suction hopper dredgers disposing of sediment at the East Sha
Chau Mud Pits must use a down-a-pipe disposal method,
the design of which must be approved in advance by Director of the CEDD. The
dredging contractor must provide equipment for such disposal.
Source: Appendix C, ETWBTC(W) No. 34/2002
7.2.7
Other Relevant Guidelines
Other guideline documents which detail how
the Contractor will comply with the WDO and its associated regulations include:
·
Waste Disposal Plan for Hong Kong
(December 1989),
Planning, Environment and Lands Branch Government Secretariat,
·
Chapter 9 - Environment (1999), Hong Kong Planning Standards and
Guidelines,
·
New Disposal Arrangements for Construction
Waste (1992), EPD &
CED,
·
Code of Practice on the Packaging,
Labelling and Storage of Chemical Wastes (1992), EPD,
·
ETWBTC(G) No. 2/93B, Public Filling
Facilities, Works Branch,
·
Waste Reduction Framework Plan, 1998 to
2007, Planning,
Environment and Lands Bureau, Government Secretariat, 5 November 1998;
·
ETWBTC(W) Nos. 25/99, 25/99A and 25/99C, Incorporation of Information on
Construction and Demolition Material Management in Public Works Sub-committee
Papers; Works Bureau,
·
ETWBTC(W) No. 12/2000, Fill Management; Works Bureau,
·
ETWBTC(W) Nos. 6/2002 and 6/2002A, Enhanced Specification for Site
Cleanliness and Tidiness. Works Bureau,
·
ETWBTC(W) No. 34/2002, Management of
Dredged/Excavated Sediment;
Environment, Transport and Works Bureau,
7.3.1
Construction Phase
During the construction phase, the main activities,
which will result in generation of waste, include wind turbine construction
activities at the laydown area, marine dredging and
excavation of the cable trench on land.
The typical waste types associated with these activities include:
·
Dredged
marine sediment;
·
C&D
materials;
·
Chemical
waste; and
·
General
Waste and sewage from workers.
7.3.2
Operational Phase
Chemical waste comprising used mechanical oils and
lubricants contained within the turbine nacelle may need to be changed during
maintenance.
The potential environmental impacts associated with
the handling and disposal of waste arising from the construction and operation
of the wind farm were assessed in accordance with the criteria presented in Annexes 7 and 15 of the EIAO-TM.
7.5
Waste Management
Assessment
7.5.1
Construction Phase
Dredged Marine Sediment
Submarine cabling will be required for the wind farm
internal grid to the offshore substation and from the substation to the landing
point at the Lamma Power Station Extension. For the base case option, ie the offshore substation, the total cable path length is
expected to be approximately 17.3 km (13 km for the internal array and 4.3 km
from the substation to the landing point), whereas, for the onshore substation
option, the total cable path length is expected to be 48.3 km (14.6 km for the
internal turbine array and 33.7 km for the six cables to the grab dredging
area).
The proposed methodology for cable construction is
discussed in Section 5. The majority of the submarine cable will
be installed by jetting techniques, only a small amount of sediment will be
disturbed at the seabed and the majority will subsequently settle over the
cables and therefore no dumping will be required.
Grab dredging will also be required to
create an underwater trench near to the shore in
preparation for the landing of cables.
It is conservatively estimated that for the base case option 3,000 m3
of sediment will be dredged in this area and will require off-site disposal.
Contaminated Dredged Marine Sediment
EPD has implemented a comprehensive marine water
quality monitoring programme since 1986.
This has comprised the monitoring of seabed sediments at a total of 60
stations. The Southwest Lamma site lies in the Southern Waters Water Control Zone
as defined by EPD, which covers 400 km2 of water stretching from
Hong Kong Island south to Lantau Island facing the
South China Sea ([2]).
As discussed in Section
6, two EPD sediment sampling stations (SS3 and SS4) are located in
proximity to the wind farm site and cable route. The location of these sampling stations
is shown in Figure 6.2, Section
6.
The results of EPD sediment monitoring at the above
sites between the period 2003 and 2007 is shown in Table 7.3.
A comparison of the data with the sediment quality
criteria (i.e., Lower Chemical Exceedance Level
(LCEL) and Upper Chemical Exceedance Level (UCEL)
(see Table 7.3) shows that the
sediments in the local area of the wind farm site are largely comprised fine
material and are relatively unpolluted.
The levels of heavy metals, Polycyclic Aromatic Hydrocarbons (PAHs) and Polychlorinated Biphenyls (PCBs) are well below
the LCEL specified in ETWBTC(W) 34/2002.
As discussed in Section
6, seabed sediment sampling was also undertaken in April 2009 in the
proposed nearshore grab dredging area in order to
classify sediments to be dredged. A
total of 5 samples were collected in the nearshore
area to the landing point for contaminant analyses. The location of the sample points are
shown in Figure 6.3.
Summary results from the survey are presented in Table 7.4.
The results of the nearshore
sediment survey show that sediments in the area that will be disturbed as a
result of this Project are largely uncontaminated. However, copper was elevated above LCEL
at sampling station 1. This
therefore means that sediments at sampling stations 2 to 5 are classified as
Category L sediment, which are suitable for Open Sea Disposal, and sediments at
sampling station 1 are classified as Category M sediment, which may need
confined marine disposal pending biological testing.
Under the current design arrangements for the cable
route, grab dredging will occur in the area covered by samples 1, 2, 3 and 4
(see Section 6). Sampling station 1 is located in the
footprint of the proposed cable route and therefore within the proposed
dredging area. However, slight
adjustment of the cable route to the north will mean that dredging works would
not be undertaken in the area where contaminants are found at sampling station
1. A sediment sample has been taken
and analysed at sampling station 5 to the north of station 1, where sediments
have been found to be uncontaminated.
Under such a revised alignment, all sediments to be dredged would be
classified as Category L sediment suitable for Type 1 Open Sea Disposal. Under the current design and cable
alignment arrangement, Tier III biological screening would need to be performed
on the sediment sample taken from station 1, which exceeds the LCEL ([3]).
It is therefore recommended that the cable landing be shifted northwards
into to the area where no contamination has been found, i.e. through the area
in the vicinity of sample station 5.
Table 7.3 Results
of EPD Sediment Monitoring at Stations in proximity to the
|
Parameter |
EPD Monitoring Station |
LCEL |
UCEL |
|
|
|
SS3 |
SS4 |
|
|
|
PSD <63 μm (%w/w) |
73 (52 - 92) |
74 (46 - 96) |
- |
- |
|
COD (mg kg-1) |
18000 (15000 – 25000) |
16000 (14000 – 23000) |
- |
- |
|
Ammonia Nitrogen (mg kg-1) |
5.4 (1.7 – 13.0) |
3.4 (1.3 – 6.5) |
- |
- |
|
Total
Kjeldahl Nitrogen (mg kg-1) |
380 (240 - 470) |
370 (240 – 500) |
- |
- |
|
Total Phosphorous (mg kg-1) |
220 (180 – 270) |
190 (150 – 250) |
- |
- |
|
Total Sulphide (mg kg-1) |
33 (4 – 72) |
41 (8 – 140) |
- |
- |
|
Total Carbon (%w/w) |
0.9 (0.6 - 1.0) |
0.8 (0.6 - 1.0) |
- |
- |
|
Arsenic (mg kg-1) |
7.0 (6.1 - 7.9) |
7.3 (6.1 – 8.8) |
12 |
42 |
|
Cadmium (mg kg-1) |
<0.1 (<0.1 - <0.1) |
<0.1 (<0.1 - <0.1) |
1.5 |
4 |
|
Chromium (mg kg-1) |
32 (25 - 38) |
34 (26 - 41) |
80 |
160 |
|
Copper (mg kg-1) |
19 (15 - 23) |
28 (18 - 38) |
65 |
110 |
|
Lead (mg kg-1) |
35 (23 - 41) |
38 (25 - 49) |
75 |
110 |
|
Mercury (mg kg-1) |
0.1 (0.08 - 0.10) |
0.11 (0.08 - 0.20) |
0.5 |
1 |
|
Nickel (mg kg-1) |
23 (19 - 25) |
22 (16 - 26) |
40 |
40 |
|
Silver (mg kg-1) |
0.2 (<0.2 – 0.2) |
0.4 (0.2 – 0.6) |
1 |
2 |
|
Zinc (mg kg-1) |
93 (75 – 110) |
100 (75 – 130) |
200 |
270 |
|
Total PCBs (µg kg-1) |
18 (18 – 18) |
18 (18 – 18) |
23 |
180 |
|
Low Molecular Weight PAHs
(µg
kg-1) |
91 (90 – 95) |
93 (90 – 110) |
550 |
3160 |
|
High Molecular Weight PAHs
(µg
kg-1) |
58 (23 – 110) |
89 (40 – 160) |
1700 |
9600 |
|
a. Values in non-brackets
represent the mean value across the data set. Values in brackets represent
the range in the data set. b. Data enclosed in
brackets indicate the ranges regardless of the depths. c. Data presented are
arithmetic mean and data presented in bracket indicate the minimum and
maximum data range of each parameter. d. Low Molecular Wt PAHs include acenaphthene, acenaphthylene, anthracene, fluoreneand phenanthrene. e. High Molecular Wt PAHs include benzo[a]anthracene, benzo[a]pyrene, chrysene, dibenzo[a,h]anthracene, fluoranthene, pyrene, benzo[b]fluoranthene, benzo[k]fluoranthene, indeno[1,2,3- c,d]pyrene and benzo[g,h,I]perylene. f. LCEL = Lower Chemical Exceedance Level g. UCEL = Upper Chemical Exceedance Level |
||||
Table 7.4 Sediment
Survey Results
|
Parameter |
Sampling Station |
LCEL |
UCEL |
||||
|
|
1 |
2 |
3 |
4 |
5 |
|
|
|
Ammonia Nitrogen (mg kg-1) |
<10 |
<10 |
<10 |
<10 |
<10 |
- |
- |
|
Nitrite (mg kg-1) |
<0.5 |
<0.5 |
<0.5 |
<0.5 |
<0.5 |
|
|
|
Nitrate (mg kg-1) |
<0.5 |
<0.5 |
<0.5 |
<0.5 |
<0.5 |
|
|
|
Total
Kjeldahl Nitrogen (TKN) (mg kg-1) |
1170 |
1300 |
1150 |
1220 |
300 |
- |
- |
|
Total Phosphorous (mg kg-1) |
624 |
911 |
702 |
778 |
300 |
- |
- |
|
Total Carbon (%w/w) |
0.98 |
1.03 |
1.02 |
1.04 |
1.07 |
- |
- |
|
Arsenic (mg kg-1) |
8 |
10 |
10 |
10 |
10 |
12 |
42 |
|
Cadmium (mg kg-1) |
<0.2 |
<0.2 |
<0.2 |
<0.2 |
<0.2 |
1.5 |
4 |
|
Chromium (mg kg-1) |
44 |
41 |
42 |
44 |
43 |
80 |
160 |
|
Copper (mg kg-1) |
74 |
26 |
25 |
32 |
25 |
65 |
110 |
|
Lead (mg kg-1) |
39 |
39 |
41 |
44 |
37 |
75 |
110 |
|
Mercury (mg kg-1) |
0.07 |
0.07 |
0.09 |
0.10 |
0.07 |
0.5 |
1 |
|
Nickel (mg kg-1) |
27 |
26 |
27 |
28 |
26 |
40 |
40 |
|
Silver (mg kg-1) |
0.2 |
0.2 |
0.2 |
0.2 |
0.2 |
1 |
2 |
|
Zinc (mg kg-1) |
121 |
116 |
115 |
121 |
115 |
200 |
270 |
|
Total PCBs (µg kg-1) |
<3.0 |
<3.0 |
<3.0 |
<3.0 |
<3.0 |
23 |
180 |
|
Low Molecular Weight PAHs
(µg
kg-1) |
<550 |
<550 |
<550 |
<550 |
<550 |
550 |
3160 |
|
High Molecular Weight PAHs
(µg
kg-1) |
<1700 |
<1700 |
<1700 |
<1700 |
<1700 |
1700 |
9600 |
|
a. LCEL = Lower Chemical Exceedance Level b. UCEL = Upper Chemical Exceedance Level c. Cells shaded in grey
indicate levels greater than LCEL d. No LCEL / UCEL values
for Ammonia Nitrogen, Nitrite, Nitrate, TKN, Total Phosphorous and Total
Carbon |
|||||||
The testing results presented in this report are for
EIA purposes only. It is likely
that further analysis will be required for the purpose of application of a
Dumping Permit for the sediments. A
proposal for sampling and chemical testing of the sediment will be prepared and
submitted to the EPD for approval.
The approved detailed sampling and chemical testing will be carried out
prior to the commencement of the dredging activities to confirm the sediment
disposal method. After carrying out
the sampling and testing, a Sediment Quality Report (SQR) will be
prepared for EPD approval as required under the Dumping at Sea Ordinance.
The SQR will include the sampling details, the chemical testing results,
quality control records, proposed classification and delineation of sediment
according to the requirements of the Appendix A of ETWBTC(W) No. 34/2002.
The final disposal site will be determined by the MFC
and a dumping licence will be obtained from the DEP prior to the commencement
of the dredging works.
The potential water quality impacts due to the
dredging and disposal of these sediments have been assessed and are presented
in Section 6.
C&D Materials
As discussed in Section
5, a section of the existing seawall at the Lamma
Power Station Extension will be removed so that the submarine cable can be
installed via a steel cable slipway for cable landing and connection to
grid.
Between 2,145 m3 (offshore
substation option) to 3,400 m3 (onshore substation) of rock
revetment material will be removed.
This material will be stockpiled at the lay down area. Once formed, the steel cable slipway
will then be buried and the seawall reinstated, and therefore, no waste will be
produced. All material excavated
will be reused to reinstate the seawall and therefore no waste will be
generated.
On the landward side of the seawall, a 250m long
trench will be constructed to the existing Switching Station for cable
laying. This trench will be 1m wide and 1m in depth and therefore a total of 250 m3
of material will be excavated. All of this material will be reused as
refill for the trench and therefore no waste will be generated.
It is expected that the substation will largely be
constructed from prefabricated form and therefore waste generation should be
nominal.
Chemical Wastes
Chemical substances likely to be generated from the
construction of the wind farm will, for the most part, arise from the
maintenance of construction plant and equipment and potential spillage from
marine vessels. These may include,
but not limited to the following:
·
Scrap
batteries or spent acid/alkali from their maintenance;
·
Engine
oils, hydraulic fluids and waste fuel;
·
Spent
mineral oils/cleaning fluids from mechanical machinery; and
·
Spent
solvents/solutions from equipment cleaning activities.
Chemical wastes may pose environmental, health and
safety hazards if not stored and disposed of in an appropriate manner as
outlined in the Waste Disposal (Chemical
Waste) (General) Regulation and the Code
of Practice on the Packaging, Labelling and Storage of Chemical Wastes. These hazards may include:
·
Toxic
effects to workers;
·
Adverse
effects on air, water and land from spills; and
·
Fire
hazards.
The amount of chemical waste that will arise from the
construction activities will be highly dependent on the Contractor’s
maintenance activities and the quantity of plant, vessels and equipment
utilized. With respect to the
nature of construction plant and equipment to be used, it is anticipated that
the quantity of chemical waste to be generated will be small (in the order of a
few hundred litres per month). With
the incorporation of suitable arrangements for the storage, handling,
transportation and disposal of chemical wastes under the requirements stated in
the Code of Practice on the Packaging,
Labelling and Storage of Chemical Waste, no adverse environmental and
health impacts, and hazards will result from the handling, transportation and
disposal of chemical waste arising from the Project.
Sewage
Sewage will arise from the construction workforce,
site office’s sanitary facilities and from portable toilets. If not properly managed, these materials
could cause odour and potential health risks to the workforce by attracting
pests and other disease vectors.
It is conservatively assumed up to 300 construction
workers will be involved in the construction of the offshore wind farm. With a sewage generation rate of 0.15 m3/worker/day
([4]), about 45 m3 of sewage will be
generated per day. The sewage generated
will be conveyed to public sewage treatment works (STW).
Onshore assembly will occur at the Lamma Power Station with facilities connected to sewerage
mains. Offshore sewage will be
handled by appropriate sewage holding facilities on vessels. Therefore no adverse impacts associated
with sewage are expected.
General Refuse
The presence of a construction site with workers and
associated site office will result in the generation of general refuse (mainly
consist of food waste, aluminium cans and waste paper) which requires off-site
disposal. The storage of general
refuse has the potential to give rise to adverse environmental impacts. These include odour if the waste is not
collected frequently, windblown litter, water quality impacts if waste enters
water bodies, and visual impact.
These secondary impacts are discussed in Section 6. The site may also attract pests, vermin,
and other disease vectors if the waste storage areas are not well maintained
and cleaned regularly. Licensed
chemical waste management contractor will be engaged for the collection,
handling, transportation and disposal of the general refuse.
Assuming up to approximately 300 construction workers
will be working on site at any one time.
With a general refuse generation rate of 0.65 kg per worker per day ([5]), the amount of general refuse to be
generated will be about 195 kg per day.
Recyclable materials such as paper and aluminium cans
will be separated and delivered to the recyclers. Adequate number of waste containers will
be provided to avoid over-spillage of waste. The non-recyclable waste will be
collected and disposed of at the
Provided that the mitigation measures recommended in Section 7.6.6 are adopted, no adverse environmental impacts caused by the storage,
handling, transport and disposal of general refuse are expected.
7.5.2
Operational Phase
Chemical Wastes
Each of the turbine nacelles will contain lubricants
and hydraulic oils (nominally 100 l of gearbox oil, 250 l of hydraulic oil, 20
l of motor oil, 2,500 l of transformer oil and potentially limited quantities
of coolant depending on design).
The potential release of these fluids and the potential for water
quality impacts is considered in Section
6. Routine maintenance of the
offshore structure will generate waste products, such as gear oil and hydraulic
fluids, and these will be disposed of by means of controlled disposal methods
on land.
Sewage
Sewage will arise from the operation staff that
monitor the operation of the wind farm and act as maintenance crew. However, operational staff will be
located at the Lamma Power Station and existing
sewage facilities will be used.
Offshore sewage will be handled by appropriate sewage holding facilities
on vessels. Therefore no adverse
impacts associated with sewage are expected.
General Refuse
General refuse will arise from the operation staff
and administrative activities.
General refuse may consist of food waste, plastic, aluminium can and waste
paper. However, operational staff
will be located within current facilities at the Lamma
Power Station and existing procedures for waste management will be
adopted. Only a small amount of
waste is expected to be generated in addition to the existing waste stream and
therefore only minor impacts are expected in this regard.
7.5.3
Waste Arising Summary
The summary of the various waste types likely to be
generated during the construction and operational phases for the Project are
summarized in Table 7.5.
Table 7.5 Summary
of Waste Arising
|
Waste
material type |
Total
quantities generated |
Quantities to be reuse on-site |
Quantities to be disposed off-site |
Disposal |
|
Construction
Phase |
||||
|
Dredged Marine Sediment (Underwater
trench for cable landing) |
3,000 m3 |
- |
3,000 m3 |
Type 1 Open Sea Disposal (Subject to
detailed testing results prior to dredging and EPD approval). |
|
Rock revetment material |
2,145 m3 (offshore
substation) or 3,400 m3 (onshore substation)
|
All rock revetment materials will be used
for trench reinstate |
- |
- |
|
Excavated
materials |
250 m3 |
All excavated materials will be used for
backfilling |
- |
- |
|
Chemical Waste |
Few hundred litres per month |
- |
Few hundred litres per month |
Chemical
Waste Treatment Centre |
|
Sewage from workforces |
45 m3 per day |
- |
45 m3 per day |
Conveyed to public sewage treatment or
handled by appropriate sewage holding facilities on vessels |
|
General Refuse |
195 kg per day |
- |
195 kg per day |
To be collected by licensed waste
collector for disposal of at landfill. |
|
Operational
Phase |
||||
|
Chemical Waste |
Few hundred litres per year |
- |
Few hundred litres per year |
Chemical Waste Treatment
Centre |
|
Sewage workforces |
Few litres per day |
- |
Few litres per day |
Existing sewage facilities at Lamma Power Station and appropriate sewage holding
facilities on vessels |
|
General Refuse |
Few kilogram per day |
- |
Few kilogram per day |
Will use the current facilities and waste
management procedure at the Lamma Power Station. |
7.6
Mitigation of
Adverse Impacts
This section recommends the mitigation measures and
good site practices to avoid or reduce potential adverse environmental impacts
associated with handling, collection and disposal of waste arising from the
construction and operation of the proposed wind farm.
The Contractors will incorporate these recommendations
into a Waste Management Plan for the construction works. The Contractors will submit the plan to
HK Electric’s Engineer Representative for endorsement prior to the commencement
of the construction works. This
plan will incorporate site-specific factors, such as the designation of areas
for the segregation and temporary storage of reusable and recyclable materials.
It is the Contractor’s responsibility to ensure that
only reputable licensed waste collectors are used and that appropriate measures
to reduce adverse impacts, including windblown litter. In addition, the Contractor must ensure
that all the necessary permits or licences required under the Waste Disposal Ordinance are obtained for the
construction and operational phases.
Waste Management Hierarchy
The various waste management options are categorised
in terms of preference from an environmental viewpoint. The options considered to be most
preferable have the least environmental impacts and are more sustainable in the
long term. The hierarchy is as
follows:
·
Avoidance
and reduction;
·
Reuse
of materials;
·
Recovery
and recycling; and
·
Treatment
and disposal.
The above hierarchy has been used to evaluate and
select waste management options.
The aim has been to reduce waste generation and reduce waste handling
and disposal costs.
HK Electric will ensure that their contractors
consult the EPD for the final disposal of wastes and as appropriate implement
the good site practices and mitigation measures recommended in this EIA Study
and those given below.
·
Nomination
of approved personnel to be responsible for good site practices, arrangements
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;
·
Provision
of sufficient waste disposal points and regular collection for disposal;
·
Appropriate
measures to reduce windblown litter and dust transportation of waste by either
covering trucks or by transporting wastes in enclosed containers;
·
Separation
of chemical wastes for special handling and appropriate treatment at the
Chemical Waste Treatment Centre;
·
Regular
cleaning and maintenance programme for drainage systems, sumps and oil
interceptors; and
·
A
recording system for the amount of wastes generated/recycled and disposal
sites.
Waste Reduction Measures
Good management and control can prevent generation of
significant amount of waste. Waste
reduction is best achieved at the planning and design stage, as well as by
ensuring the implementation of good site practices. Recommendations to achieve waste
reduction include:
·
Reuse
any material excavated on land for fill and reinstatement of the seawall;
·
Segregation
and storage of different types of waste in different containers, skips or
stockpiles to enhance reuse or recycling of material and their proper disposal;
·
Encourage
collection of aluminium cans and waste paper by individual collectors during
construction with separate labelled bins provided to segregate these wastes
from other general refuse by the workforce;
·
Any
unused chemicals and those with remaining functional capacity be recycled as
far as possible;
·
Proper
storage and site practices to reduce the potential for damage or contamination
of construction materials; and
·
Plan
and stock construction materials carefully to reduce amount of waste generated
and avoid unnecessary generation of waste.
7.6.1
Submarine Cable Alignment
It is proposed that the cable alignment under existing
design arrangements be altered to avoid contaminated sediment. It is suggested that the cable route
avoids the nearshore sample station 1 and is shifted
northwards slightly to run through the area in vicinity to sample station 5 (Figure
6.3). This will ensure that
sediments at sample station 1, where elevated levels of copper have been noted,
is avoided.
7.6.2
Dredged Sediments
Disposal of sediments dredged during construction will
be in accordance with the requirements
of the ETWBTC(W) No. 34/2002.
Detailed sampling and chemical testing will be
carried out prior to the commencement of the dredging activities to confirm the
sediment disposal method. The final
disposal site will be determined by the Marine Fill Committee (MFC) and a
dumping licence will be obtained from EPD prior to the commencement of the
dredging works. Uncontaminated sediments will be
disposed of at open sea disposal sites designated by the MFC.
Section 6 has set a range of measures
that will ensure that the release of dredging arisings
into the environment are minimised. Some of these measures are repeated
below:
·
Dredged
marine mud will be disposed of in a gazetted marine disposal area in accordance
with the Dumping at Sea Ordinance (DASO) permit conditions;
·
Disposal
barges will be fitted with tight bottom seals in order to prevent leakage of
material during transport;
·
Barges
will be filled to a level, which ensures that material does not spill over
during transport to the disposal site and that adequate freeboard is maintained
to ensure that the decks are not washed by wave action;
·
After
dredging, any excess materials will be cleaned from decks and exposed fittings
before the vessel is moved from the dredging area;
·
When the dredged
material has been unloaded at the disposal areas, remove any material that has
accumulated on the deck or other exposed parts of the vessel and place in the
hold or a hopper. Do not wash decks
clean in a way that permits material to be released overboard;
·
During dredging operations, cage type silt
curtains will be installed whenever necessary to enclose the dredging areas
next to the grab dredgers; and
·
Closed grab dredgers should be used to
minimise the potential for leakage of sediments.
7.6.3
Excavated Materials
All C&D materials (rock and soil) will be reused
within the Project. In addition,
the following good management measures shall be adopted with respect to
excavated material:
·
Stockpiles
shall be located away from waterfront or storm drains as far as possible;
·
Open
stockpiles of construction materials (for examples, aggregates, sand and fill
material) of more than 50 m3 should be covered with tarpaulin or
similar fabric during rainstorms.
Measures should be taken to prevent the washing away of construction
materials, soil, silt or debris into any drainage system;
·
Every vehicle should be washed to remove
any dusty materials from its body and wheels before leaving a construction
site;
·
The area where vehicle washing takes place
and the section of the road between the washing facilities and the exit point
should be paved with concrete, bituminous materials or hardcores;
·
The load of dusty materials carried by
vehicle leaving a construction site should be covered entirely by clean
impervious sheeting to ensure dust materials do not leak from the vehicle;
·
All dusty materials should be sprayed with
water prior to any loading, unloading or transfer operation so as to maintain
the dusty materials wet; and
·
The height from which excavated materials
are dropped should be controlled to a minimum practical height to limit
fugitive dust generation from unloading.
7.6.4
Chemical Waste
Chemical waste producers will be registered with the
EPD.
Chemical waste, as defined by Schedule 1 of the Waste
Disposal (Chemical Waste) (General) Regulation, will be handled in accordance
with the Code of Practice on the
Packaging, Handling and Storage of Chemical Wastes as follows. Containers used for storage of chemical
wastes will:
·
Be suitable for the substance they are
holding, resistant to corrosion, maintained in a good condition, and securely
closed;
·
Have a capacity of less than 450 l unless
the specifications have been approved by the EPD; and
·
Display a label in English and Chinese in
accordance with instructions prescribed in Schedule
2 of the Regulations.
The storage area for chemical wastes will:
·
Be clearly labelled and used solely for the
storage of chemical waste;
·
Be enclosed on at least 3 sides;
·
Have an impermeable floor and bunding, of capacity to accommodate 110% of the volume of
the largest container or 20% by volume of the chemical waste stored in that
area, whichever is the greatest;
·
Have adequate ventilation;
·
Be covered to prevent rainfall entering
(water collected within the bund must be tested and disposed of as chemical
waste, if necessary); and
·
Be arranged so that incompatible materials
are appropriately separated.
Chemical waste will be disposed of:
·
Via a licensed waste collector; and
·
To a facility licensed to receive chemical
waste, such as the Chemical Waste Treatment Facility which also offers a
chemical waste collection service and can supply the necessary storage
containers.
7.6.5
Sewage
An adequate number of portable toilets, if necessary,
will be provided for the on-site construction workforce. Any waste should be transferred to a
sewage treatment works by a licensed collector.
7.6.6
General Refuse
General refuse will be stored in enclosed bins or
compaction units separately from construction and chemical wastes. A reputable waste collector will be
employed by the Contractor to remove general refuse from the site, separately
from construction and chemical wastes, on a daily basis to reduce odour, pest
and litter impacts. The burning of
refuse on construction sites is prohibited by law.
Recycling bins will be provided at strategic
locations to facilitate recovery of aluminium can and waste paper from the
site. Materials recovered will be
sold for recycling.
7.6.7
Staff Training
Training will be provided to workers on the concepts
of site cleanliness and appropriate waste management procedures, including waste
reduction, reuse and recycling at the beginning of the construction works.
7.7
Residual
Environmental Impacts
With the implementation of the recommended mitigation
measures, no adverse residual impacts are anticipated from the construction and
operation of the wind farm.
7.8
Environmental Monitoring and
Audit Requirements
7.8.1
Construction Phase
To facilitate monitoring and control over the
contractors’ performance on waste management, a waste monitoring and audit
programme will be implemented throughout the construction phase. The aims of the monitoring and audit
programme are:
·
To
review the Contractor’s WMP including the quantities and types of C&D
materials generated, reused and disposed of off-site; the amount of fill materials
exported from/imported to the site and the quantity of timber used in temporary
works construction for each process/activity;
·
To
monitor the implementation and achievement of the WMP on site to assess its
effectiveness; and
·
To
monitor the follow-up action on deficiencies identified.
Joint site audits by the HK Electric and the
contractor at the onshore laydown area will be
undertaken on a weekly basis.
Particular attention will be given to the contractor’s provision of
sufficient spaces, adequacy of resources and facilities for on-site sorting and
temporary storage of C&D materials.
The findings of the waste audits will be reported in
the Environmental Monitoring and Audit Reports.
7.8.2
Operational Phase
No adverse environmental impacts are expected for the
operational phase of the wind farm, and therefore, waste monitoring and an
audit programme will not be required.
No adverse
impacts are expected with respect to the handling and disposal of waste arising
from the construction and operation of the wind farm. A range of best practice mitigation
measures are, however, proposed to minimise the impact of waste
management. In addition, monitoring
and audit measures are proposed to ensure that robust measures are promoted to
minimise impacts and that waste is controlled effectively.