Environmental Legislation, Policies, Plans, Standards and Criteria
Identification of Potential Sources of Impact
Evaluation of Residual Impacts
Table 6.1 Sediment Quality Criteria for the Classification of Sediment
Table 6.2 Test Species for Biological Testing
Table 6.3 Test endpoints and decision criteria for biological testing
Table 6.4 Contaminant Levels of Vibrocore Samples and Their Categories
Table 6.5 Summary of Waste Handling Procedures and Disposal Routes
Table 6.6 Summary of Fill Requirements and Potential Sources
Figure 6.1 Sediment Sampling Locations
6.1 This section identifies the types of wastes that are likely to be generated during the construction of the Road P1 Advance Works and evaluates the potential environmental impacts that may result from these waste arisings. The main solid waste issues are related to dredged marine sediment from the construction of the seawall. Mitigation measures and good site practices, including waste handling, storage and disposal, are recommended with reference to the applicable waste legislation and guidelines.
6.2 The operation phase of the Road P1 Advance Works would generate wastes associated with roadside littering, and the amount would be expected to be minimal. The potential environmental impacts arising from the handling and disposal of this small amount of waste are anticipated to be negligible and therefore have not been evaluated further in this report.
6.3 The criteria and guidelines for assessing waste management implications are outlined in Annex 7 and Annex 15 of the Technical Memorandum on Environmental Impact Assessment Ordinance (EIAO-TM), respectively.
6.4 The following legislation relates to the handling, treatment and disposal of wastes in the Hong Kong SAR and will be used in assessing potential impacts:
§ Waste Disposal Ordinance (Cap. 354);
§ Waste Disposal (Chemical Waste) (General) Regulation (Cap. 354);
§ Land (Miscellaneous Provisions) Ordinance (Cap. 28);
§ Public Health and Municipal Services Ordinance (Cap. 132) - Public Cleansing and Prevention of Nuisances Regulation; and
§ Dumping At Sea Ordinance (Cap. 466).
6.5 The Waste Disposal Ordinance (WDO) prohibits the unauthorised disposal of wastes. 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 waste building, or civil engineering materials, but does not include animal waste. Under the WDO, wastes can be disposed of at sites licensed by the EPD.
6.6 Under the regulation of WDO, the Chemical Waste (General) Regulation 1992 provides regulations for chemical waste control, and administers the possession, storage, collection, transport and disposal of chemical wastes. The Environmental Protection Department (EPD) has also issued a ‘guideline’ document, the Code of Practice on the Packaging, Labelling and Storage of Chemical Wastes (1992), which details how the Contractor should comply with the regulations on chemical wastes.
6.7 The Public Cleansing and Prevention of Nuisances Regulation provides control on illegal tipping of wastes on unauthorised (unlicensed) sites.
6.8 The ETWB TCW No. 34/2002 sets out the new procedure for seeking approval to dredge / excavate sediment and the management framework for marine disposal of dredged / excavated sediment. This Technical Circular outlines the requirements to be followed in assessing and classifying the sediment and explains the marine disposal arrangement for the classified material. The sediment quality criteria for the classification of sediment are presented in Table 6.1.
6.9 Dumping permits from the Territory Control Group of EPD are required for marine disposal of dredged materials.
6.10 The current policy related to the dumping of C&D material[1] is documented in the Works Branch Technical Circular No. 2/93, ‘Public Dump’. 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 Land (Miscellaneous Provisions) Ordinance requires that dumping licences are obtained by individuals or companies who deliver public fill to public filling areas. The licences are issued by the Civil Engineering Department (CED) under delegated powers from the Director of Lands.
6.11 Under the proposed Waste Disposal (Charges for Disposal of Construction Waste) Regulation to be implemented in 2005, construction waste delivered to a landfill for disposal must not contain more than 50% by weight of inert material. Construction waste delivered to a sorting facility for disposal must contain more than 50% by weight of inert material, and construction waste delivered to a public fill reception facility for disposal must consist entirely of inert material.
6.12 Measures have been introduced under Environment, Transport and Works Bureau (ETWB) TCW No. 33/2002 to enhance the management of C&D material including rock, and to minimize its generation at source. The enhancement measures include: (i) drawing up a Construction and Demolition Material Management Plan (C&DMMP) at an early design stage to minimize C&D material generation; (ii) vetting of the C&DMMP prior to upgrading of the project to Category A in the Public Works Programme; and (iii) providing the contractor with information from the C&DMMP in order to facilitate him in the preparation of the Waste Management Plan (WMP) and to minimize C&D material generation during construction. Projects generating C&D material less than 50,000m3 or importing fill material less than 50,000m3 are exempt from the C&DMMP. A new technical circular ETWB TCW 15/2003 was recently issued to introduce additional measures to enhance waste management on construction sites. The circular sets out the policy and procedures requiring contractors to prepare and implement an enhanced WMP to encourage on-site sorting of C&D material and to minimize their generation during the course of construction.
6.13 The preliminary C&DMMP prepared for this Project had been submitted and endorsed by Public Filling Committee (PFC) in May 2003. Upon completion of the detailed design of this Project, a finalized C&DMMP will be submitted to CED Vetting Committee and the PFC for approval.
6.14 The criteria for assessing waste management implications are outlined in Annex 7 of the EIAO-TM. The methods for assessing potential waste management impacts during the construction phase 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.
6.15 Marine site investigation works of the Project were carried out in November and December 2002 and included laboratory testing of contaminants to determine the level of contamination in the marine sediments at the existing seabed. The works included vibrocoring at 5 locations in which the vibrocores were taken at a spacing of 100m within the proposed area of dredging. The sampling points are presented in Figure 6.1.
6.16 Chemical Testing was carried out for all vibrocores taken from the 5 locations. Each sub-sample recovered from vibrocoring was tested in the laboratory for the following parameters:
(i) Metals concentrations including chromium (Cr), copper (Cu), mercury (Hg), lead (Pb), cadmium (Cd), nickel (Ni), zinc (Zn), silver (Ag) and arsenic (As).
(ii) Concentrations of organic compounds including total polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs), and tributyltin (TBT).
6.17 Under the new management and classification system, dredged sediments destined for marine disposal are classified according to their level of contamination by 13 contaminants as detailed in Table 6.1:
Table 6.1 Sediment Quality Criteria for the Classification of Sediment
|
Contaminants |
LCEL |
UCEL |
|
Heavy Metal (mg/kg dry weight) |
||
|
Cadmium (Cd) |
1.5 |
4 |
|
Chromium (Cr) |
80 |
160 |
|
Copper (Cu) |
65 |
110 |
|
Mercury (Hg) |
0.5 |
1 |
|
Nickel (Ni) |
40 |
40 |
|
Lead (Pb) |
75 |
110 |
|
Silver (Ag) |
1 |
2 |
|
Zinc (Zn) |
200 |
270 |
|
Metalloid (mg/kg dry weight) |
||
|
Arsenic |
12 |
42 |
|
Organic-PAHs (µg/kg dry weight) |
||
|
PAHs (Low Molecular Weight) |
550 |
3160 |
|
PAHs (High Molecular Weight) |
1700 |
9600 |
|
Organic-non-PAHs (µg/kg dry weight) |
||
|
Total PCBs |
23 |
180 |
|
Organometallics (µg-TBT L-1 in interstitial water) |
||
|
Tributyltin |
0.15 |
0.15 |
Source: Appendix A of ETWB TCW No. 34/2002 Management of Dredged / Excavated Sediment
Note: LCEL – Lower Chemical Exceedance Level
UCEL – Upper Chemical Exceedance Level
6.18 Sediments are categorised with reference to the LCEL and UCEL, as follows:
Category L Sediment with all contaminant levels not exceeding the LCEL. The material must be dredged, transported and disposed of in a manner that minimises the loss of contaminants either into solution or by suspension.
Category M Sediment with any one or more contaminant levels exceeding the LCEL and 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 Sediment with any one or more contaminant levels exceeding the UCEL. The material must be dredged and transported with great care, and must be effectively isolated from the environment upon final disposal.
6.19 In case of Category M and Category H contamination under the new system, the final determination of appropriate disposal options, routing and the allocation of a permit to dispose of material at a designated site will be made by EPD and the Marine Fill Committee (MFC) in accordance with the ETWB TCW No. 34/2002.
6.20 For Category M sediment, Tier III biological screening was carried out to determine the appropriate disposal methods in accordance with the requirements of ETWB TCW No. 34/2002.
§ a 10‑day burrowing amphipod toxicity test ;
§ a 20‑day burrowing polychaete toxicity test; and
§ a 48‑96 hour larvae (bivalve) toxicity test.
6.21 The species used for each type of biological test and the test conditions are listed in Table 6.2 below.
Table 6.2 Test Species for Biological Testing
|
Test Types |
Species |
Reference Test Conditions* |
|
10‑day burrowing amphipod toxicity test
|
Leptocheirus plumulosus
|
U.S.EPA (1994) |
|
20‑day burrowing polychaete toxicity test |
Neanthes arenaceodentata |
PSEP (1995)
|
|
48‑96 hour bivalve larvae toxicity test |
Crassostrea gigas
|
PSEP (1995) |
Notes:*
(i) U.S.EPA (U.S. Environmental Protection Agency) 1994. Methods for assessing the toxicity of sediment-associated contaminants with estuarine and marine amphipods. Office of Research and Development. U.S. Environmental Protection Agency, Cincinnati, OH. EPA/600/R94/025.
(ii) PSEP (Puget Sound Estuary Program) 1995. Recommended guidelines for conducting laboratory bioassays on Puget Sound sediments.
6.22 Sediment samples were characterized by the testing laboratory for ancillary testing parameters such as porewater salinity, ammonia, TOC, grain size and moisture content. This provided necessary information on the general characteristics of the sediment.
6.23 The test endpoints and decision criteria are summarized in Table 6.3. The sediment was deemed to have failed the biological testing if it failed in any one of the three toxicity tests.
Table 6.3 Test endpoints and decision criteria for biological testing
|
Toxicity test
|
Endpoints measured
|
Failure criteria |
|
10-day amphipod
|
Survival
|
Mean survival in test sediment is significantly different (p£0.05)1 from mean survival in reference sediment and mean survival in test sediment < 80% of mean survival in reference sediment.
|
|
20-day polychaete |
Dry Weight2 |
Mean dry weight in test sediment is significantly different (p£0.05)1 from mean dry weight in reference sediment and mean dry weight in test sediment < 90% of mean dry weight in reference sediment.
|
|
48-96 hour bivalve larvae
|
Normality Survival3 |
Mean normality survival in test sediment is significantly different (p £0.05)1 from mean normality survival in reference sediment and mean normality survival in test sediment < 80% of mean normality survival in reference sediment.
|
1 Statistically significant differences should be determined using appropriate two-sample comparisons (e.g., t-tests) at a probability of p£ 0.05.
2 Dry weight means total dry weight after deducting dead and missing worms.
3 Normality survival integrates the normality and survival end points, and measures survival of only the normal larvae relative to the starting number.
6.24 The marine sediment quality analysis results of chemical testing from the site investigation works, as compared with the sediment quality criteria for the classification of sediment, are presented in Table 6.4.
6.25 The sediment chemical testing results indicate that Category L sediments were found at all depths at all vibrocores apart from one sediment sample at vibrocore V2. Localized category M sediment was found at sampling depth 18 m – 19.9 m at V2 due to marginal exceedance of the LCEL for the contaminant arsenic of 12 mg/kg. This sediment sample at V2 was required to proceed to Tier III biological screening.
Table 6.4 Contaminant Levels of Vibrocore Samples and Their Categories
|
Vibrocore No. |
Depth (m) |
(mg/kg) |
(mg/kg) |
(mg/kg) |
(mg/kg) |
Metals (mg/kg) |
Sediment Category |
|||||||||
|
From |
To |
Cd |
Cr |
Cu |
Ni |
Pb |
Zn |
Hg |
As |
Ag |
||||||
|
V1 |
0.17 |
0.90 |
<55 |
<170 |
<2 |
<0.015 |
0.1 |
23 |
15 |
15 |
35 |
93 |
0.2 |
7.8 |
<0.1 |
L |
|
V1 |
0.90 |
1.90 |
<55 |
<170 |
<2 |
<0.015 |
0.1 |
27 |
21 |
18 |
53 |
110 |
0.4 |
11 |
0.2 |
L |
|
V1 |
1.90 |
2.90 |
<55 |
<170 |
<2 |
<0.015 |
<0.1 |
21 |
6.6 |
15 |
20 |
49 |
<0.05 |
3.6 |
<0.1 |
L |
|
V1 |
2.90 |
4.90 |
<55 |
<170 |
<2 |
<0.015 |
0.1 |
23 |
8.7 |
15 |
25 |
55 |
<0.05 |
4.3 |
<0.1 |
L |
|
V1 |
6.50 |
7.90 |
<55 |
<170 |
<2 |
<0.015 |
0.1 |
29 |
11 |
19 |
30 |
64 |
<0.05 |
4.8 |
<0.1 |
L |
|
V1 |
8.90 |
10.90 |
<55 |
<170 |
<2 |
<0.015 |
0.1 |
26 |
9.1 |
18 |
25 |
52 |
0.07 |
4.5 |
<0.1 |
L |
|
V1 |
12.10 |
13.90 |
<55 |
<170 |
<2 |
<0.015 |
<0.1 |
28 |
10 |
18 |
29 |
55 |
0.1 |
7.0 |
<0.1 |
L |
|
V1 |
14.90 |
16.90 |
<55 |
<170 |
<2 |
<0.015 |
<0.1 |
6.2 |
1.1 |
<1 |
12 |
<10 |
0.4 |
1.7 |
0.2 |
L |
|
V2 |
0.00 |
0.90 |
<55 |
<170 |
<2 |
<0.015 |
0.2 |
28 |
23 |
17 |
47 |
130 |
0.2 |
11 |
0.1 |
L |
|
V2 |
0.90 |
1.90 |
<55 |
<170 |
<2 |
<0.015 |
<0.1 |
24 |
13 |
16 |
32 |
56 |
0.3 |
8.7 |
<0.1 |
L |
|
V2 |
1.90 |
2.90 |
<55 |
<170 |
<2 |
<0.015 |
<0.1 |
21 |
7.3 |
15 |
20 |
50 |
0.07 |
5.2 |
<0.1 |
L |
|
V2 |
3.25 |
4.90 |
<55 |
<170 |
<2 |
<0.015 |
0.1 |
24 |
9.0 |
16 |
24 |
56 |
0.06 |
4.5 |
<0.1 |
L |
|
V2 |
6.00 |
7.90 |
<55 |
<170 |
<2 |
<0.015 |
0.1 |
28 |
10 |
18 |
27 |
60 |
0.1 |
4.7 |
<0.1 |
L |
|
V2 |
9.05 |
10.90 |
<55 |
<170 |
<2 |
<0.015 |
0.1 |
25 |
9.2 |
17 |
24 |
52 |
0.1 |
4.4 |
<0.1 |
L |
|
V2 |
12.00 |
13.90 |
<55 |
<170 |
<2 |
<0.015 |
<0.1 |
25 |
9.6 |
16 |
26 |
50 |
<0.05 |
6.2 |
<0.1 |
L |
|
V2 |
15.00 |
16.60 |
<55 |
<170 |
<2 |
<0.015 |
0.2 |
30 |
14 |
17 |
37 |
66 |
<0.05 |
10 |
<0.1 |
L |
|
V2 |
18.00 |
19.90 |
<55 |
<170 |
<2 |
<0.015 |
0.2 |
24 |
12 |
15 |
38 |
60 |
<0.05 |
13 |
<0.1 |
M |
|
V2 |
20.90 |
21.50 |
<55 |
<170 |
<2 |
<0.015 |
0.1 |
1.8 |
1.5 |
<1 |
8.6 |
<10 |
<0.05 |
<1 |
<0.1 |
L |
|
V3 |
0.66 |
0.90 |
<55 |
<170 |
<2 |
<0.015 |
<0.1 |
19 |
12 |
12 |
27 |
55 |
<0.05 |
7.1 |
<0.1 |
L |
|
V3 |
0.90 |
1.90 |
<55 |
<170 |
<2 |
<0.015 |
<0.1 |
23 |
13 |
16 |
34 |
61 |
0.1 |
9.4 |
<0.1 |
L |
|
V3 |
1.90 |
2.90 |
<55 |
<170 |
<2 |
<0.015 |
<0.1 |
20 |
6.5 |
14 |
18 |
50 |
<0.05 |
4.9 |
<0.1 |
L |
|
V3 |
2.90 |
4.90 |
<55 |
<170 |
<2 |
<0.015 |
<0.1 |
23 |
8.0 |
14 |
25 |
53 |
<0.05 |
4.8 |
<0.1 |
L |
|
V3 |
6.30 |
7.90 |
<55 |
<170 |
<2 |
<0.015 |
0.1 |
27 |
11 |
18 |
29 |
59 |
<0.05 |
5.4 |
<0.1 |
L |
|
V3 |
8.90 |
10.90 |
<55 |
<170 |
<2 |
<0.015 |
0.1 |
25 |
9.3 |
17 |
25 |
54 |
<0.05 |
4.4 |
<0.1 |
L |
|
V3 |
12.40 |
13.90 |
<55 |
<170 |
<2 |
<0.015 |
0.1 |
27 |
11 |
18 |
30 |
54 |
<0.05 |
8.0 |
<0.1 |
L |
|
V3 |
14.90 |
16.90 |
<55 |
<170 |
<2 |
<0.015 |
0.1 |
26 |
13 |
16 |
35 |
60 |
<0.05 |
10 |
0.2 |
L |
|
V3 |
18.00 |
19.50 |
<55 |
<170 |
<2 |
<0.015 |
0.1 |
7.4 |
4.2 |
3.1 |
18 |
18 |
0.2 |
2.6 |
<0.1 |
L |
Table 6.4 Contaminant Levels of Vibrocore Samples and Their Categories
|
Vibrocore No. |
Depth (m) |
(g/kg) |
(g/kg) |
(g/kg) |
(g/kg) |
Metals (mg/kg) |
Sediment Category |
|||||||||
|
From |
To |
Cd |
Cr |
Cu |
Ni |
Pb |
Zn |
Hg |
As |
Ag |
||||||
|
V4 |
0.57 |
0.90 |
<55 |
<170 |
<2 |
<0.015 |
0.1 |
27 |
17 |
18 |
37 |
100 |
0.1 |
8.5 |
<0.1 |
L |
|
V4 |
1.10 |
1.90 |
<55 |
<170 |
<2 |
<0.015 |
0.2 |
28 |
19 |
18 |
41 |
100 |
0.08 |
11 |
0.1 |
L |
|
V4 |
1.90 |
2.90 |
<55 |
<170 |
<2 |
<0.015 |
<0.1 |
20 |
7.0 |
14 |
20 |
49 |
0.3 |
4.9 |
0.1 |
L |
|
V4 |
2.90 |
4.90 |
<55 |
<170 |
<2 |
<0.015 |
<0.1 |
20 |
7.1 |
12 |
21 |
45 |
<0.05 |
4.5 |
<0.1 |
L |
|
V4 |
6.12 |
7.90 |
<55 |
<170 |
<2 |
<0.015 |
0.1 |
24 |
9.6 |
17 |
25 |
54 |
<0.05 |
4.0 |
<0.1 |
L |
|
V4 |
8.90 |
10.90 |
<55 |
<170 |
<2 |
<0.015 |
0.1 |
25 |
9.7 |
18 |
25 |
54 |
<0.05 |
4.3 |
<0.1 |
L |
|
V4 |
12.45 |
13.90 |
<55 |
<170 |
<2 |
<0.015 |
0.1 |
27 |
12 |
18 |
33 |
59 |
0.3 |
8.0 |
<0.1 |
L |
|
V4 |
14.90 |
16.90 |
<55 |
<170 |
<2 |
<0.015 |
0.2 |
24 |
12 |
14 |
34 |
58 |
<0.05 |
11 |
<0.1 |
L |
|
V4 |
18.00 |
19.90 |
<55 |
<170 |
<2 |
<0.015 |
<0.1 |
8.2 |
2.8 |
3.8 |
8.6 |
28 |
<0.05 |
1.7 |
<0.1 |
L |
|
V5 |
N/A |
N/A |
<55 |
<170 |
<2 |
<0.015 |
0.2 |
20 |
20 |
12 |
32 |
71 |
0.4 |
6.3 |
0.3 |
L |
|
V5 |
1.47 |
1.90 |
<55 |
<170 |
<2 |
<0.015 |
<0.1 |
3.6 |
1.5 |
2.2 |
5.0 |
11 |
<0.05 |
2.4 |
<0.1 |
L |
|
V5 |
1.90 |
2.90 |
<55 |
<170 |
<2 |
<0.015 |
<0.1 |
2.1 |
<1 |
1.1 |
2.2 |
<10 |
0.09 |
1.2 |
<0.1 |
L |
|
V5 |
2.90 |
4.90 |
<55 |
<170 |
<2 |
<0.015 |
<0.1 |
3.0 |
1.3 |
1.5 |
2.5 |
<10 |
<0.05 |
2.1 |
<0.1 |
L |
|
V5 |
6.53 |
7.90 |
<55 |
<170 |
<2 |
<0.015 |
<0.1 |
2.1 |
<1 |
1.3 |
2.2 |
<10 |
<0.05 |
1.4 |
<0.1 |
L |
|
V5 |
8.90 |
10.90 |
<55 |
<170 |
<2 |
<0.015 |
<0.1 |
11 |
3.8 |
7.6 |
12 |
30 |
<0.05 |
3.5 |
<0.1 |
L |
|
V5 |
12.15 |
13.90 |
<55 |
<170 |
<2 |
<0.015 |
0.2 |
20 |
10 |
12 |
30 |
49 |
<0.05 |
10 |
<0.1 |
L |
|
V5 |
14.90 |
16.70 |
<55 |
<170 |
<2 |
<0.015 |
<0.1 |
6.3 |
3.7 |
2.5 |
23 |
31 |
<0.05 |
1.4 |
<0.1 |
L |
|
Reference Sediment |
N/A |
N/A |
<55 |
<170 |
<2 |
<0.015 |
0.1 |
31 |
16 |
22 |
42 |
81 |
<0.05 |
7.7 |
<0.1 |
L |
Notes:
1. LMW = Low molecular weight PAHs, that is, acenaphthene, acenaphthylene, anthracene, fluorene, naphthalene and phenanthrene.
2. HMW = High molecular weight PAHs, that is, 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.
3. Values in underline indicate Category M sediment under ETWB TCW No. 34/2002.
6.26 The marine sediment quality analysis results of biological screening from the site investigation works are presented in a comprehensive laboratory testing report. The sediment biological screening results indicated that the sample at V2 failed the bivalve larvae toxicity test.
6.27 The construction activities to be carried out for the proposed Project would generate a variety of wastes that can be divided into distinct categories based on their composition and ultimate method of disposal. The identified waste types include:
§ dredged marine sediment;
§ construction and demolition (C&D) materials;
§ general refuse; and
§ chemical waste.
6.28 The nature of each type of waste arising is described below, together with an evaluation of the potential environmental impacts associated with these waste arisings.
6.29 The seabed area would be dredged for construction of the seawall for forming the road embankment. The total volume of dredged sediment for the Project was estimated by the Engineer to be approximately 700,000 m3. The estimated volume of Category M dredged sediment was approximately 8,000 m3. The potential environmental effects of the removal of these sediments on water quality have been assessed and presented in Section 5 of this Report.
6.30 Effort has been paid to minimize the generation of C&D material by minimizing the extent of dredging for construction of the seawalls. Drained reclamation method with marine mud left in place is proposed for the remaining reclamation to minimize the amount of dredged sediment. This dredging approach has been agreed with the Marine Fill Committee.
6.31 To minimize any potential adverse impacts arising from the dredged marine sediment, the sediment should be dredged, transported and disposed of in a manner that would minimise the loss of contaminants either into solution or by resuspension. Mitigation measures to minimise potential environmental impacts are described in Section 6.44. With the implementation of mitigation measures, no unacceptable impacts would be expected from the transportation and disposal of the dredged sediment.
6.32 The existing seawall would be removed. It was estimated that approximately 17,000m3 of rock armour and underlayer would be removed. The rock armour and underlayer would be reused on–site for surcharging.
6.33 Construction and demolition (C&D) material would also be generated from piling works for the road piers, foundation works for the concrete bridge, and excavation for the road drainage. This inert C&D material would comprise mostly soft material (soil) with an estimated volume of 20,000 m3. With good management and control, it is anticipated that almost most of the C&D material could be reused on-site as fill material for surcharging.
6.34 It is estimated that about 5,000m3 of C&D waste would be generated from general site clearance works, tree felling, piling works and formwork for viaduct and other highway structures. The C&D waste would require disposal to a government-controlled landfill.
6.35 The C&D material generated would be sorted on-site and the inert portion would be re-used on-site as far as possible to minimize the net amount of C&D material generated from this Project. Rock armour and underlayer removed from the existing seawall would also be reused for construction of seawall.
6.36 The total quantity of surcharge material required is about 150,000m3. With good management during placement of surcharge material, the lower layer of surcharge could be placed with general fill material and re-used inert C&D material generated during piling works which forms the future road embankment. With this arrangement, disposal of the lower layer of surcharge material off-site is then not required. The top layer of surcharge material could be sourced from public fill bank operated by the Government and it is envisaged that approximately 65,000m3 of surcharge material would be disposed to Penny’s Bay Reclamation Phase 2 for reclamation.
6.37 The amount of C&D material expected to be generated would be quantified in the site Waste Management Plan to be prepared by the Contractor. Since the construction activities would be located near the coast, improper management of C&D materials may introduce debris and pollutants to the marine waters, and mitigation measures would be required for good site practices.
6.38 Throughout construction, the workforce would generate general refuse comprising food scraps, waste paper, empty containers, etc. Release of general refuse into marine waters should not be permitted as introduction of these wastes is likely to have detrimental effects on water quality in the area. Rapid and effective collection of site wastes would be required to prevent waste materials being blown around by wind, flushed or leached into the marine environment, and odour nuisance. The work sites may also attract pests and vermin if the waste storage area is not well maintained and cleaned regularly. Disposal of refuse at sites other than approved waste transfer or disposal facilities can also result in similar impacts. With the implementation of waste management practices at the site, adverse environmental impacts would not be expected to arise from the storage, handling and transportation of workforce wastes.
6.39 The maintenance and servicing of construction plant and equipment may possibly generate some chemical wastes, for instance, cleaning fluids, solvents, lubrication oil and fuel. Maintenance of vehicles may also involve the use of a variety of chemicals, oil and lubricants. It is not possible 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 amount of plant utilised. The amount of chemical waste expected to be generated will be quantified in the site Waste Management Plan to be prepared by the Contractor.
6.40 Chemical wastes arising during the construction phase may pose environmental, health and safety hazards if not stored and disposed of in an appropriate manner as stipulated in the Waste Disposal (Chemical Waste) (General) Regulations. The potential hazards include:
§ toxic effects to workers;
§ adverse impacts on water quality from spills and associated adverse impacts on marine biota; and
§ fire hazards.
6.41 Materials classified as chemical wastes will require special handling and storage arrangements before removal for appropriate treatment at the Chemical Waste Treatment Facility at Tsing Yi. Wherever possible opportunities should be taken to reuse and recycle materials. Mitigation and control requirements for chemical wastes are detailed in Section 6.50. Provided that the handling, storage and disposal of chemical wastes are in accordance with these requirements, adverse environmental impacts are not expected to result.
6.42 The basic requirements and procedures for dredged mud disposal are specified under the ETWB TCW No. 34/2002. The management of the dredging, use and disposal of marine mud is monitored by the MFC, while the licensing of marine dumping is the responsibility of the Director of Environmental Protection (DEP).
6.43 The dredged marine sediments would be loaded onto barges and transported to designated disposal sites depending on their level of contamination. Based on the chemical and biological screening results, it was estimated that some 692,000 m3 of sediments would be suitable for open sea disposal and 8,000 m3 of sediments would require confined marine disposal. In accordance with the ETWB TCW No. 34/2002, the contaminated material must be dredged and transported with great care, and the mitigation measures recommended in Section 5 of this Report should be strictly followed. Furthermore, the dredged contaminated sediment must be effectively isolated from the environment upon final disposal and shall be disposed of at the East Sha Chau Contaminated Mud Pits that is designated for the disposal of contaminated mud in Hong Kong.
6.44 During transportation and disposal of the dredged marine sediments, the following measures should be taken to minimise potential impacts on water quality:
§ Bottom opening of barges shall be fitted with tight fitting seals to prevent leakage of material. Excess material shall be cleaned from the decks and exposed fittings of barges and hopper dredgers before the vessel is moved.
§ Monitoring of the barge loading shall be conducted to ensure that loss of material does not take place during transportation. Transport barges or vessels shall be equipped with automatic self-monitoring devices as specified by the DEP.
§ Barges or hopper barges shall not be filled to a level that would cause the overflow of materials or sediment laden water during loading or transportation.
6.45 It is not anticipated that adverse waste management related impacts would arise, provided that good site practices are strictly followed. Recommendations for good site practices during the construction activities include:
§ nomination of an approved personnel, such as a site manager, 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 minimise windblown litter and dust during transportation of waste by either covering trucks or by transporting wastes in enclosed containers; and
§ regular cleaning and maintenance programme for drainage systems, sumps and oil interceptors.
6.46 Good management and control can prevent the 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:
§ segregation and storage of different types of waste in different containers, skips or stockpiles to enhance reuse or recycling of materials and their proper disposal;
§ to encourage collection of aluminium cans by individual collectors, separate labelled bins shall be provided to segregate this waste from other general refuse generated by the work force;
§ proper storage and site practices to minimise the potential for damage or contamination of construction materials;
§ plan and stock construction materials carefully to minimise amount of waste generated and avoid unnecessary generation of waste; and
§ a recording system for the amount of wastes generated, recycled and disposed (including the disposal sites) should be proposed.
6.47 In addition to the above measures, specific mitigation measures are recommended below for the identified waste arisings to minimise environmental impacts during handling, transportation and disposal of these wastes.
6.48 General refuse should be stored in enclosed bins or compaction units separate from C&D material. A reputable waste collector should be employed by the contractor to remove general refuse from the site, separately from C&D material. An enclosed and covered area is preferred to reduce the occurrence of 'wind blown' light material.
6.49 In order to minimise the impact resulting from collection and transportation of C&D material for off-site disposal, the excavated material comprising reclamation fill material from the excavation works for the road formation should be reused on-site as backfilling material as far as practicable.
6.50 In order to monitor the disposal of C&D material and solid wastes at public filling facilities and landfills and to control fly-tipping, a trip-ticket system should be included. One may make reference to ETWB TCW No. 31/2004 for details.
6.51 If chemical wastes are produced at the construction site, the Contractor would be required to register with the EPD as a Chemical Waste Producer and to follow the guidelines stated in the Code of Practice on the Packaging, Labelling and Storage of Chemical Wastes. Good quality containers compatible with the chemical wastes should be used, and incompatible chemicals should be stored separately. Appropriate labels should be securely attached on each chemical waste container indicating the corresponding chemical characteristics of the chemical waste, such as explosives, flammable, oxidizing, irritant, toxic, harmful, corrosive, etc. The Contractor shall use a licensed collector to transport and dispose of the chemical wastes generated at the Chemical Waste Treatment Centre at Tsing Yi, or other licenced facility, in accordance with the Waste Disposal (Chemical Waste) (General) Regulation.
6.52 Table 6.5 provides a summary of the various waste types likely to be generated during the construction works for the Project, together with the recommended handling and disposal methods.
Table 6.5 Summary of Waste Handling Procedures and Disposal Routes
|
Waste Material Type |
Generated from works item |
Total Quantities Generated |
Quantities to be disposed off-site |
Disposal |
Handling |
|
Dredged Sediments Type 1 – Open Sea Disposal |
Seawall foundations |
692,000 m3 |
692,000 m3 |
MFC gazetted marine disposal ground |
Techniques to minimise resuspension (closed grabs, tight seal on barges, controlled loading and transfer)
|
|
Dredged Sediments Type 2 – Confined Marine Disposal |
Seawall foundations |
8,000 m3 |
8,000 m3 |
MFC gazetted marine disposal ground |
|
|
Inert C&D Material (soft material) |
Piling excavation works |
20,000 m3 |
0 m3 |
To be reused on site for surcharging |
Segregate public fill to avoid contamination from other waste arisings |
|
C&D Waste |
Piling excavation, formwork, site clearance |
5,000 m3 |
5,000 m3 |
To be disposed to landfill |
Stockpile separately to avoid contamination of inert C&D material |
|
Inert C&D Material (rock armour & underlayer)
|
Removal of existing seawall |
17,000 m3 |
0 m3 |
Suitable armour/ underlayer to be reused on site for construction of seawall |
Segregate public fill to avoid contamination from other waste arisings
|
|
Inert C&D Material (public fill) |
Removal of surcharge (top layer) (Note 1) |
65,000 m3 |
65,000 m3 |
Upper layer of public fill to be disposed to Penny’s Bay Reclamation Phase 2 |
|
|
General Refuse |
Waste paper, empty container generated from workforce |
- |
- |
Refuse station for compaction and containerisation and then to landfill |
Provide on-site refuse collection points |
|
Chemical Waste |
Cleansing fluids, solvent, lubrication oil and fuel from construction plants and equipment |
- |
- |
Chemical Waste Treatment Centre |
Recycle on-site or by licensed companies Stored on-site within suitably designed containers |
(1) Estimated total quantity of surcharge is about 150,000m3. Lower layer of surcharge of general fill materials to be reused on-site for road embankment.
6.53 With the implementation of the recommended mitigation measures for the handling, transportation and disposal of the identified waste arisings, no adverse residual impact was anticipated during the construction of the proposed Project.
6.54 Waste management would be the contractor’s responsibility to ensure that all wastes produced during the construction of the Project are handled, stored and disposed of in accordance with good waste management practices and EPD’s regulations and requirements. The recommended mitigation measures should form the basis of the site Waste Management Plan to be developed by the Contractor in the construction stage.
6.55 This Project requires fill materials to be imported for reclamation. The key aspects concerning the fill requirements and potential sources of fill material have been discussed in the Preliminary C&DMMP endorsed by the PFC. Table 6.6 provides a summary of the various type of fill materials to be required during reclamation works for the Project, together with the recommended source of fill materials.
Table 6.6 Summary of Fill Requirements and Potential Sources
|
Fill Material Type |
Required for Works Item |
Total Quantities Required |
Quantities to be Imported |
Potential source |
|
Sand Fill |
Seawall foundations (Note 1) |
354,000 m3 |
354,000 m3 |
Contractor’s own source and Infrastructure Contracts (Note 2) |
|
Filter layer / sand blanket |
96,000 m3 |
96,000 m3 |
||
|
Rock Fill (Cat 0 & Grade 200) |
Seawall |
250,000 m3 |
250,000 m3 |
Contractor’s own source and other designed contracts via Public Fill Committee confirmed at a later stage |
|
Rock Armour |
Seawall |
30,000 m3 |
13,000 m3 |
Suitable rock Armour removed from existing seawall and Contractor’s own source |
|
Public Fill |
Reclamation filling |
210,000 m3 |
210,000 m3 |
Fill bank in Tuen Mun Area 38
|
|
Top layer of Surcharge (Note 3) |
65,000 m3 |
65,000 m3 |
Fill bank in Tuen Mun Area 38 |
|
|
General fill |
Bottom layer of surcharge (road embankment) |
65,000 m3 |
65,000 m3 |
Contractor’s own source |
Note: (1) Selection of marine sand fill as seawall foundations shall be subjected completion of detailed design.
(2) Use of sand fill surcharge from Sunny Bay Reclamation is subjected to further discussion regarding availability of stockpiling area during the detailed design stage.
(3) Estimated total quantity of surcharge is about 150,000m3. 20,000m3 from inert C&D material (soft material). Bottom layer of surcharge of general fill materials to be reused on-site for road embankment.
6.56 A review of the sediment quality data from the marine ground investigation indicated that the majority of marine sediments to be dredged for the construction of the seawall were classified as Category L. The total dredged volume for the Project was estimated as approximately 700,000 m3, of which 8,000 m3 of sediments were classified as Category M requiring Type 2 confined marine disposal. With the implementation of the recommended mitigation measures and management procedures in accordance with the requirements of ETWB TCW No. 34/2002, no adverse residual impact was predicted.
6.57 Other waste types generated by the construction activities are likely to include C&D material (rock armour and soft material from piling and excavation works), general refuse from the workforce and chemical wastes from the maintenance of construction plant and equipment. Provided that these identified waste arisings are to be handled, transported and disposed of using approved methods and that the recommended good site practices are to be strictly followed, adverse environmental impacts would not be anticipated.
6.58 Fill materials required from construction of reclamation and road formation works include sand fill, rock fill, rock armour, public fill and general fill materials sourced from reusing inert C&D materials generated on-site, contractor’s own source and public fill bank operated by the Government. The Preliminary C&DMMP has been endorsed by PFC in May 2003 and upon completion of the detailed design, a finalized C&DMMP for this Project will be required for submission to PFC for approval.
6.59 The waste management assessment carried out in the NLDFS-EIA recommended good waste management practices to ensure that adverse environmental impacts from the NLDFS are prevented. The assessment concluded that no unacceptable environmental impacts would result from the storage, handling, collection, transport and disposal of wastes arising from the construction and operation of the NLDFS developments. As discussed above, our detailed assessment has further confirmed that adverse environmental impacts associated with the identified waste arisings generated by the construction activities of the Project would not be anticipated.
[1] “C&D material” contains a mixture of inert and non-inert material. The inert portion is the “public fill” and the non-inert portion is the “C&D waste”.