6.                  WASTE MANAGEMENT IMPLICATIONS

Introduction

 

6.1              The proposed project is expected to involve minor dredging and reclamation works at Tai Lam Kok (TLK).  The major issues that relate to waste management implications are dredged marine sediments, construction and demolition materials and general construction wastes.

 

6.2              The operation of the proposed Castle Peak Road improvement works 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.

 

6.3              This section identifies the potential wastes arising from the construction of the project and assesses the potential environmental impacts of their handling and disposal.  The assessment methodology and criteria are also outlined.

 

Environmental Legislation, Standards and Guidelines

 

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 (Urban Council) and (Regional Council) By-laws; and

·        Dumping At Sea Ordinance (Cap 466)

 

6.5              The following documents, circulars and guidelines which relate to waste management and disposal in Hong Kong SAR will also be referred to during the study:

 

·        Waste Disposal Plan for Hong Kong (December 1989), Planning, Environment and Lands Branch, Hong Kong Government Secretariat;

·        Environmental Guidelines for Planning in Hong Kong (1990), Hong Kong Planning and Standards Guidelines, Hong Kong Government;

·        New Disposal Arrangements For Construction Waste (1992), Environmental Protection Department And Civil Engineering Department;

·        Code Of Practice On The Packaging, Labelling And Storage Of Chemical Wastes (1992), Environmental Protection Department;

·        Waste Reduction Framework Plan, 1998-2007 (1998), Planning, Environment and Lands Branch, Hong Kong Government Secretariat;

·        Works Branch Technical Circular (WBTC) No. 2/93, Public Dumps;

·        WBTC No. 2/93B, Public Filling Facilities;

·        WBTC No. 16/96, Wet Soil in Public Dumps;

·        WBTC No. 4/98 & 4/98A, Use of Public Fill in Reclamation and Earth Filling Projects;

·        WBTC No. 5/98, On Site Sorting Of Construction Waste On Demolition Sites;

·        WBTC No. 5/99 & 5/99A, Trip-ticket System for Disposal of Construction and Demolition Material;

·        WBTC No. 19/99, Metallic Site Hoardings and Signboards;

·        WBTC No. 25/99, 25/99A & 25/99B, Incorporation of Information on Construction and Demolition Material Management in Public Works Subcommittee Papers;

·        WBTC No. 3/2000, Management of Dredged/Excavated Sediment;

·        WBTC No. 12/2000, Fill Management; and

·        WBTC No. 29/2000, Waste Management Plan.

 

Waste Management

 

6.6              The WBTC No. 3/2000 sets out the management framework for dredged/excavated sediment.  This Technical Circular outlines the new procedures to be followed in assessing and classifying the sediment and explains the marine disposal arrangement for the classified material.  All projects which involve the marine disposal of dredged/excavated sediment, except those projects or portions of projects whose construction work will commence before 31 December 2001, shall follow the new management framework.  Under the preliminary construction programme, the dredging works are scheduled to commence in June 2003, and therefore the requirements of WBTC No. 3/2000 would apply.  The new sediment quality criteria for the classification of sediment are presented in Table 6.1

 

Chemical Waste

 

6.7              Under the Waste Disposal (Chemical Waste) (General) Regulations all producers of chemical waste must register with the EPD and treat their wastes, either utilising on-site plant licensed by the EPD, or arranging for a licensed collector to transport the wastes to a licensed facility.  The regulation also prescribes the storage facilities to be provided on site, including labelling and warning signs, and requires the preparation of written procedures and training to deal with emergencies such as spillages, leakages or accidents arising from the storage of chemical wastes.

 

Construction and Demolition (C&D) Materials

 

6.8              The current policy relating to the dumping of construction and demolition (C&D) material 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 Provision) Ordinance requires that dumping licenses are obtained by individual or companies who deliver public fill to public filling areas.  The licenses are issued by the Civil Engineering Department (CED) under delegated powers from the Director of Lands.

 

6.9              In addition to the Works Branch Technical Circular, EPD and CED have produced a leaflet titled ‘New Disposal Arrangements for Construction Waste’ (1992) which states that C&D material with less than 30% by weight (or 20% inert material by volume) of inert material (i.e. public fill) will be accepted at landfill.  If the material contains more than 30% inert material, the waste must be sorted with suitable material and sent to public filling area and the non-inert material (i.e. C&D waste) sent to landfill for final disposal.

 

Assessment Methodology

 

6.10          The criteria for evaluation the potential construction waste management implications are set out in Annexes 7 of the EIAO-TM.  The method for assessing potential waste management impacts during construction phase follow those presented in Annexes 15 of EIAO-TM and include the following:

 

·        Estimation of the types and quantities of the waste 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.

 

Marine Dredged Materials

 

6.11          The marine ground investigation works were carried out in September 2000 and included laboratory testing of contaminants to characterize the level of contamination in the marine sediments at TLK.  The works included vibrocoring at 11 locations and grab sampling at 5 locations.

 

6.12          Each sub-sample recovered from vibrocoring has been laboratory tested for the following parameters unless otherwise specified:

 

·        Metals concentrations including chromium (Cr), copper (Cu), mercury (Hg), lead (Pb), cadmium (Cd), nickel (Ni), silver (Ag),  zinc (Zn) and Arsenic (As).

·        Concentrations of organic compounds including total polychlorinated biphenlys (PCBs), polyaromatic hydrocarbons (PAHs), and tributyltin (TBT) for each sub-sample from the top three sampling depths from each vibrocoring location.

·        Nutrient (total inorganic nitrogen, ammoniacal nitrogen, total organic nitrogen, total P and ortho-P).

·        Total sulphide.

·        Particle size analysis.

 

6.13          Each grab sample was tested for TBT in interstitial water.  The potential water quality impacts associated with the dredging of sediment will be discussed in Section 5 on Water Quality Assessment.

 

6.14          Under the new management and classification system, dredged sediments destined for marine disposal are classified according to their level of contamination by thirteen contaminants (Table 6.1).

 

Table 6.1         Sediment Criteria under the New Classification System

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 in interstitial water)

Tributyltin

0.15

0.15

            Source: Appendix A of WBTC No. 3/2000 Management of Dredged/Excavated Sediment

Note:    LCEL – Lower Chemical Exceedance Level

UCEL – Upper Chemical Exceedance Level

 

6.15          The sediment will be categorized 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.

 

6.16          In the 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 the designated site will be made by the EPD and Marine Fill Committee (MFC) in accordance with WBTC No. 3/2000.

 

Baseline Conditions

 

Existing Sediment Characteristics

 

6.17          A sediment sampling and testing survey within the Study Area was undertaken to provide an indication of the sediment quality for the purpose of the EIA study.  Figure 6.1 shows the sediment sampling locations.  The sediment testing results indicate that the majority of the sediment is classified as Category L.  Category H sediment was found at vibrocore VB9 (0.9-1.9m) location due to the contaminant level of Pb exceeding the UCEL (Table 6.2).  In addition, at vibrocore VB5 (1.9-2.1m) the marine mud is classified as Category M due to the reported contaminant level of As of 14 mg/kg marginally exceeding the LCEL of 12 mg/kg (Table 6.2).  However, sampling locations VB5 and VB9 are outside the area where dredging of marine mud for the foundation of the new seawall for TLK to Ka Loon Tsuen (KLT) is identified to be required (Figure 6.1).

Table 6.2 Sediment Quality Analysis Results from Marine Ground Investigation Works

 

Vibrocore

Sampling Depth

Metals and Metalloid Content (mg/kg)

ug/kg

Overall

Ag

As

Cd

Cr

Cu

Ni

Pb

Zn

Hg

Total PCBs

PAHs Low (1)

PAH High (2)

TBT in Sediment

Classification

VB1A

0-0.9m

0.2

3

<0.2

13

10

6

16

35

<0.1

<2

<35

<50

<0.5

Category L

 

0.9-1.9m

<0.1

2

<0.2

7

2

5

13

17

<0.1

<2

<35

<50

<0.5

Category L

 

1.9-2.9m

<0.1

<1

<0.2

3

3

<1

36

29

<0.1

<2

<35

<50

<0.5

Category L

VB2A

0-0.9m

0.1

3

<0.2

14

11

8

15

39

<0.1

<2

<35

<50

2

Category L

 

0.9-1.9m

0.2

3

<0.2

14

11

7

15

40

<0.1

<2

<35

<50

<0.5

Category L

VB3A

0-1.37m

<0.1

3

<0.2

9

4

4

41

22

<0.1

<2

<35

<50

<0.5

Category L

 

1.37-2.37m

<0.1

4

<0.2

7

2

7

10

21

<0.1

<2

<35

<50

<0.5

Category L

VB4A

0-0.9m

0.1

3

<0.2

14

13

9

16

47

<0.1

<2

<35

<50

6

Category L

 

0.9-1.9m

<0.1

2

<0.2

11

3

6

10

26

<0.1

<2

<35

<50

1

Category L

 

1.9-2.9m

<0.1

4

<0.2

14

5

10

13

36

<0.1

<2

<35

<50

<0.5

Category L

 

2.9-3.9m

<0.1

4

<0.2

6

2

3

9

19

<0.1

**

**

**

**

Category L

VB5

0-0.9m

<0.1

<1

<0.2

4

3

1

14

31

<0.1

<2

<35

<50

2

Category L

 

0.9-1.9m

<0.1

3

<0.2

13

6

7

20

26

<0.1

<2

<35

<50

<0.5

Category L

 

1.9-2.1m

<0.1

14

<0.2

12

6

11

30

47

<0.1

<2

<35

<50

<0.5

Category M

 

2.9-3.9m

<0.1

<1

<0.2

4

1

<1

23

17

<0.1

**

**

**

**

Category L

 

3.9-4.87m

<0.1

<1

<0.2

4

<1

2

33

17

<0.1

**

**

**

**

Category L

VB6

0-0.9m

<0.1

3

<0.2

10

6

6

19

26

<0.1

<2

<35

<50

<0.5

Category L

 

0.9-1.9m

<0.1

1

<0.2

4

2

3

11

16

0.2

<2

<35

<50

<0.5

Category L

 

1.9-2.9m

<0.1

2

<0.2

7

1

2

9

11

<0.1

<2

<35

<50

<0.5

Category L

VB7

0-1.2m

<0.1

2

<0.2

7

4

4

35

19

<0.1

<2

<35

<50

<0.5

Category L

VB7D

0-0.9m

<0.1

7

<0.2

16

20

9

45

48

<0.1

<2

<35

<50

2

Category L

 

0.9-1.8m

<0.1

6

<0.2

13

13

8

48

35

<0.1

<2

<35

<50

<0.5

Category L

VB8

0.25-1.25m

<0.1

4

<0.2

8

9

5

48

24

<0.1

<2

<35

<50

1

Category L

 

1.25-2.25m

<0.1

1

0.3

4

10

1

41

13

<0.1

<2

<35

<50

<0.5

Category L

 

2.25-3.15m

0.2

<1

<0.2

2

9

<1

44

11

<0.1

<2

<35

<50

<0.5

Category L

VB9

0-0.9m

0.2

3

<0.2

12

15

8

57

69

<0.1

9

<35

305

1

Category L

 

0.9-1.9m

0.2

<1

1.7

3

2

<1

185

11

<0.1

<2

<35

<50

<0.5

Category H

 

1.9-2.1m

<0.1

<1

<0.2

2

2

<1

11

16

<0.1

<2

<35

<50

<0.5

Category L

VB9A

0-0.9m

<0.1

4

<0.2

9

3

2

13

14

<0.1

<2

<35

<50

<0.5

Category L

 

0.-9-1.9m

<0.1

3

<0.2

8

2

2

10

14

<0.1

<2

<35

<50

<0.5

Category L

Notes:

1. Low molecular weight PAHs i.e. acenaphthene, acenaphthylene, anthracene, fluorene, naphthalene and phenanthrene

2. High molecular weight PAHs i.e. benzo[a]anthracene, benzo[a]pyrene, chrysene, dibenzo[a,h]anthracene, fluoranthene, pyrene, benzo[b]fluoranthene, benzo[k]fluoranthene, ideno[1,2,3-c,d]pyrene and benzo[g,h,I]perylene.

3. Value in underline indicate Category M sediment under WBTC No. 3/2000

4. Value in bold indicate Category H sediment under WBTC No. 3/2000

6.18          The testing of TBT in interstitial water indicates that sediment at GS1 and GS4 have exceeded the criteria of 0.15 mg-TBT/L (Table 6.3).  GS1 and GS4 are located close to the Brothers Point Landing Facilities at Tai Lam Kok, which could be one reason for the TBT exceedence.  GS4 is located outside the proposed area of dredging for the new sea wall.  Other than GS1 and GS4, the testing results indicated that no TBT exceedences were found at the other grab sampling locations.  The marine mud at the proposed reclamation at TLK is classified as Category L, apart from the seabed at sampling location GS1 which is classified as Category H (biological test not required) due to TBT exceedence.

 

Table 6.3         Results of Testing of TBT in Interstitial Water

Grab Sampling Location

TBT (mg-TBT/ L-1)

GS1

0.21

GS2

0.15

GS3

0.08

GS4

0.2

GS5

<0.05

 

Identification of Impacts

 

6.19          Construction activities to be carried out for the proposed road improvement will result in the generation of a variety of wastes which may include:

 

·        Dredged marine materials;

·        Construction and demolition (C&D) material which comprises public fill material and C&D waste;

·        Chemical wastes; and

·        General refuse.

 

6.20          If not properly managed, the handling and disposal of these waste arisings may cause environmental impact and nuisance.  The nature of each type of waste is discussed below together with an evaluation of the potential environmental impacts associated with these waste types.

 

Prediction and Evaluation of Environmental Impacts

 

Marine Dredged Materials

 

6.21          According to the latest information from the engineering team, a small-scale reclamation of size 8,034m2 is proposed at Tai Lam Kok and dredging will be required for the seawall foundation from Ka Loon Tsuen to Tai Lam Kok.  As the volume of the dredged category L sediment will be below 50,000 m3, a dredged reclamation is proposed.  The quantities of dredged material and alluvium are estimated to be 49,736m3 and 222,240m3 for the proposed reclamation at Tai Lam Kok and the proposed seawall from Ka Loon Tsuen to Tai Lam respectively.  According to the preliminary construction programme, dredging is scheduled from June 2003 to November 2003 and from March 2005 to May 2005.

 

6.22          In order to minimize any potential adverse impacts arising from the dredged marine sediment, the sediment should be dredged, transported and disposed of in a manner which minimizes the loss of contaminants either into solutions or by resuspension.  Mitigation measures to minimize potential environmental impacts are recommended in 6.35-6.37.  It is anticipated that, provided these recommended mitigation measures are enforced, no unacceptable impacts will result from the transportation and disposal of the dredged sediment.

 

Construction and Demolition Materials

 

6.23          Construction and demolition (C&D) material will comprise unwanted materials generated during construction and may include:

 

·        Wood from formwork and falsework;

·        Materials and equipment wrappings;

·        Unusable/surplus concrete/grouting mixes; and

·        Damaged contaminated surplus construction materials.

 

6.24          The inert portion of C&D material (e.g. rock, concrete, etc.) which can be used as fill material for reclamation and earth filling projects is termed public fill.  The non-inert portion (e.g. timber, glass, plastic etc.) which should be disposed of at landfills is termed C & D waste.

 

6.25          The volume of construction waste generated will be dependent on the Contractor’s operating procedures and practices.  Demolition material will be generated from the removal of CLP’s electricity sub-station at the entry to the access road leading to CSD’s staff quarters and from demolition of the crown wall of the existing seawall.  Based on the preliminary construction programme, the demolition of the electricity sub-station is scheduled to take place from June 2003 to September 2003.  The demolition of the crown wall of the existing seawall is scheduled to take place in two stages between May 2004 to July 2004 and October 2005 to December 2005.  The estimated quantity of C&D material from removal of CLP’s electricity sub-station and the crown wall is approximately 60 m3 and 2,500 m3, respectively.  In addition, demolition material will be generated from the demolition of the existing drainage pipes and water mains, with an estimated quantity of approximately 200 m3.  This demolition work is scheduled to take place during the periods from May 2004 to October 2004 and from November 2005 to April 2006.  These demolition materials are classified as public fill materials.

 

6.26          The amount of C&D material expected to be generated will be quantified in the site Waste Management Plan to be prepared by the Contractor.  Since the construction activities will be located near the waterfront, improper management of C&D materials or spillage of slurry / grouting mixes may introduce debris and pollutants to the coastal waters.

 

6.27          C&D material generated from the demolition works should be sorted on-site into public fill which should be re-used on-site as far as possible, and C&D waste which may need to be disposed of to landfill.  C&D material from the demolition of the electricity sub-station and the crown wall can be re-used as public fill material in the proposed reclamation at Tai Lam Kok. In the worst case, about 200 m3 of C&D wastes generated from the demolition of existing drainage pipe and watermains may need to be disposed of at landfill.  By reducing the quantity of C&D material requiring off-site disposal, the potential for environmental impacts from the transportation of material by road will also be reduced (such as noise impact, possible congestion due to increased traffic flows, and dust and exhaust emissions from the haul vehicles).

 

6.28          Inert C&D material arising from the excavation works for the existing pavement and from the laying of utilities will be generated during the periods from December 2004 to March 2005 and from January 2006 to September 2006.  The inert material from pavement excavation which is estimated to be approximately 5,400m3 can be reused on site.  In addition to the pavement waste,  surplus soil fill material with an estimated quantity of 2,500m3 will be generated from utilities laying during the period January 2006 to April 2006.  The surplus soil will require off-site disposal to public filling areas, as the material will be generated after the reclamation is completed.  The resulting potential impact from the additional traffic arising from transporting this amount of excavated material is not expected to be adverse as the excavation works under the road reconstruction will be carried out in stages.

 

Chemical Waste

 

6.29          Construction plant and equipment will require regular maintenance and servicing which will generate chemical waste such as cleaning fluids, solvents, lubrication oil and fuel.  Vehicle maintenance will also involve the use of a variety of chemicals and lubricants, including heavy duty cleaners, organic solvents, degreasers, brake fluids, battery acid and soldering fluids.

 

6.30          Chemical waste may pose serious environmental, health and safety hazards if it is not properly managed.  These hazards may include:

 

·        Toxic effects to workers;

·        Adverse effects on water quality from spills; and

·        Fire hazards.

 

6.31          The amount of chemical waste that will arise from the construction activities will be highly dependent on the Contractor’s on-site maintenance requirements and the amount of plant utilized.  It is anticipated that the quantity of chemical waste, such as lubricating oil and solvent, produced from plant maintenance will be relatively small.  These types of waste will be readily accepted at the Chemical Waste Treatment Facility at Tsing Yi.  The amount of chemical waste expected to be generated will be quantified in the site Waste Management Plan to be prepared by the Contractor.

 

6.32          Storage, handling, transport and disposal of chemical waste should be arranged in accordance with the Code of Practice on the Packaging, Labelling and Storage of Chemical Wastes published by the EPD.  Wherever possible opportunities should be taken to reuse and recycle materials.  Mitigation and control requirements for chemical wastes are detailed in Section 6.44 - 6.48.  Provided that this occurs, and the chemical waste is disposed of at a licensed chemical waste treatment and disposal facility, the potential environmental impacts arising from the storage, handling and disposal of a small amount of chemical waste generated from the construction activities will be minimal.

 

General Refuse

 

6.33          The workforce will generate general refuse, including paper and food waste, throughout construction.  The storage of general refuse has the potential to give rise to environmental impacts.  These include water quality, odour if waste enters nearby water bodies, odour and visual impact.  The worksites may also attract pests and vermin if the storage areas are not well maintained and cleaned regularly.  In addition, disposal of waste at sites other than approved waste transfer or disposal facilities can also lead to environmental impacts.

 

6.34          If the refuse is stored and transported in accordance with good practices and disposed at licensed landfills, the potential environmental impacts will be minimal.

 

Mitigation of Adverse Environmental Impacts

 

Marine Sediments

 

6.35          The basic requirements and procedures for dredged mud disposal are specified under the WBTC No. 3/2000.  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). 

 

6.36          The dredged marine sediments will be loaded onto barges and transported to designated disposal sites depending on their level of contaminants.  As discussed in Section 6.17, the majority of the marine sediment to be dredged is Category L.  CED have advised that the uncontaminated mud can be disposed at the South Cheung Chau marine disposal ground.  The Category H contaminated material (GS1), however, must be dredged and transported with great care.  Therefore appropriate dredging methods should be incorporated into the water quality mitigation measures, such as the use of closed-grab dredgers.  Furthermore, the dredged contaminated sediment must be effectively isolated from the environment upon final disposal and shall be disposed at the East Sha Chau Contaminated Mud Pits which is designated for the disposal of contaminated mud.  In accordance with the requirements of WBTC No. 3/2000, the project proponent shall submit a formal Sediment Quality Report to DEP at least 3 month prior to the dredging contract being tendered. 

 

6.37          During transportation and disposal of the dredged marine sediments, the following measures shall be taken to minimize 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 specified by the DEP.

 

Good Site Practice and Waste Reduction Measures

 

6.38          It is not anticipated that adverse waste management related impacts would arise, provided that good site practice is strictly followed.  Recommendations for good site practice during the construction activities include:

 

·        Use waste haulier authorized or licensed to collect specific category of waste;

·         Obtain the necessary waste disposal permits from the appropriate authorities, if they are required, in accordance with the Waste Disposal Ordinance (Cap 354, Waste Disposal (Chemical Waste) (General) Regulation (Cap 354), the Land (Miscellaneous Provision) Ordinance (Cap 28);

·        nomination of an approved personnel, such as a site manager, to be responsible for good site practice, 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;

·        separation of chemical wastes for special handling and appropriate treatment at the CWTF;

·        regular cleaning and maintenance programme for drainage systems, sumps and oil interceptors;

·        a recording system for the amount of wastes generated, recycled and disposed of (including the disposal sites);

·        In order to monitor the disposal of C&D and solid wastes at public filling facilities and landfills, and control fly-tipping, a trip-ticket system should be included as one of the contractual requirements and implemented by the Environmental Team.  One may make reference to WBTC No. 5/99 for details; and

·        A Waste Management Plan (WMP) should be prepared and this WMP should be submitted to the Engineer for approval.  One may make reference to WBTC No. 29/2000 for details.

 

6.39          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 practice.  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;

·        any unused chemicals or those with remaining functional capacity shall be recycled;

·        use of reusable non-timber formwork to reduce the amount of C&D material;

·        prior to disposal of C&D waste, it is recommended that wood, steel and other metals shall be separated for re-use and / or recycling to minimise the quantity of waste to be disposed of to landfill;

·        proper storage and site practices to minimise the potential for damage or contamination of construction materials; and

·        plan and stock construction materials carefully to minimize amount of waste generated and avoid unnecessary generation of waste.

 

6.40          In addition to the above good site practice and waste reduction measures, specific mitigation measures are recommended below for the identified waste arisings to minimize environmental impacts during handling, transportation and disposal of these wastes.  The transportation of these wastes by barge to the disposal location is recommended, as far as practicable, in order to reduce potential noise and air quality impacts from road transportation.

 

Construction and Demolition Waste

 

6.41          Careful design, planning and good site management can minimize over-ordering and generation of waste materials such as concrete, mortar and cement grouts.  The design of formwork should maximize the use of standard wooden panels so that high reuse levels can be achieved.  Alternatives such as steel formwork or plastic facing should be considered to increase the potential for reuse.

 

6.42          The contractor should use as much of the C&D material as possible on-site.  Proper segregation of waste types on site will increase the feasibility of certain components of the waste stream by recycling contractors.

 

6.43          To maximize landfill life, Government policy discourages the disposal of C&D wastes with more than 20% inert material by volume (or 30% inert material by weight) at landfill.  Inert C&D material (public fill) are directed to reclamation areas, where they have the added benefit of offsetting the need for removal of materials from borrow areas for reclamation purposes, or to an approved public filling area (PFA).  Due to limited space at landfills, disposal at reclamation sites or a PFA would be the preferred method. 

 

Chemical Waste

 

6.44          After use, chemical wastes should be handled according to the Code of Practice on the Packaging, Labeling and Storage of Chemical Wastes.  Spent chemicals should be stored and collected by an approved operator for disposal at the Chemical Waste Treatment Facility or other licensed facility in accordance with the Chemical Waste (General) Regulation.

 

6.45          Containers used for the storage of chemical waste should:

 

·        Be suitable for the substance they are holding, resistant to corrosion, maintained in good condition, and securely closed;

·        Have a capacity of less than 450 litres 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.

 

6.46          The storage area for chemical waste should:

 

·        Be clearly labeled 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 disposal as chemical waste if necessary); and

·        Be arranged so that incompatible materials are adequately separated.

 

6.47          Disposal of chemical waste should:

 

·        Be via a licensed waste collector: and

·        Be a facility licensed to receive chemical waste, such as the Chemical Waste Treatment Facility which offers a chemical waste collection service and can supply the necessary storage containers; or

·        Be a reuser of the waste, under approval from the EPD.

 

6.48          The Center for Environmental Technology operates a Waste Exchange Scheme which can assist in finding receivers or buyers for the small quantity of chemical waste to be generated from the project.

 

General Refuse

 

6.49          General refuse should be stored in enclosed bins or compaction units separate from C&D and chemical wastes.  A reputable waste collector should be employed by the contractor to remove general refuse from the site, separately from C&D and chemical wastes, on a daily or every second day basis to minimize odour, pest and litter impacts. 

 

6.50          Aluminum cans are often recovered from the waste stream by individual collectors if they are segregated or easily accessible, so separate labeled bins for their deposit should be provided if feasible. Site office waste can be reduced through recycling of paper if volumes are large enough to warrant collection.  Participation in a local collection scheme should be considered if one is available.

 

Imported Fill

 

6.51          For the construction of the proposed seawall from Ka Loon Tsuen to Tai Lam Kok, the following estimated marine fill materials are required:

 

Material Type:                                                  Quantity (m3)

Armour:                                                            154,323

Rock:                                                               46,800

Sand (placed hydraulically under water):            204,060

 

6.52          The armour and rock have specific grading limit to meet the functional requirement of the seawall.  The sand fill will be placed hydraulically under water and cannot be replaced by public fill.

 

6.53          For the land fill required for the construction of the widened road from Tai Lam Kok to Siu Lam, it is estimated that the quantity of the imported fill is less than 50,000 m3.  According to WBTC No. 4/98 the use of public fill should be considered if the imported fill requirements is greater than 300,000 m3.  As the quantity of imported fill is relatively small, it is not necessary to use public fill.

 

Summary of Wastes Generated and Imported Fill

 

6.54          A summary of the quantity of the waste material generated by this project and their disposal method is shown in Table 6.4.

 

Table 6.4         Summary of Wastes Generated

 

Type

Quantity (m3)

Disposal Method

Dredged Marine material

49,736

Disposed to gazetted marine disposal ground*

Dredged Alluvium

222,240

Reused on site or other reclamation projects. Dispose any surplus dredged alluvium to gazetted marine disposal ground*

Demolition of crown wall of existing seawall

2,500

Reused on site

Demolition of electricity sub-station

60

Reused on site

Demolition of existing drainage pipes and water mains

200

Reused on site/Disposed to Landfill

Excavated material

5,400

Reused on site

Surplus soil fill after utilities laying

2,500

Disposed to public filling areas

*              Contaminated sediment would require confined marine disposal i.e. category H sediment at GS1.

 

6.55          The quantities of imported fill and their source are summarized in Table 6.5.

 

Table 6.5         Summary of Imported Fill

 

Type

Quantity (m3)

Source

Armour

154,323

other public works contracts or Contractor’s source

Rock

46,800

other public works contracts or Contractor’s source

Sand (placed hydraulically)

204,060

Contractor’s source

land soft fill

<50,000

other public works Contracts or Contractor’s source

 

Residual Environmental Impacts

 

6.56          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 project.  

 

Environmental Monitoring and Audit

 

6.57          It is recommended that auditing of each waste stream be carried out periodically to determine if waste is being managed in accordance with approved procedures and the site waste management plan. The audits should look at all aspects of waste management including waste generation, storage, recycling, treatment, transport, and disposal.  An appropriate audit programme would be to undertake a first audit at the commencement of the construction works, and then to audit quarterly thereafter. 

 

Conclusion

 

6.58          A review of the sediment quality data from the marine ground investigation works indicated that the majority of the marine sediments in the proposed dredging area for the TLK reclamation and new seawall from TLK to KLT are classified as category L.  This dredged sediment will therefore be suitable for open sea disposal.  The small volume of sediment classified as Category H at the TLK reclamation will require confined marine disposal.

 

6.59          An assessment of the potential environmental impacts of waste arising from the construction of the project has been conducted.  Wastes generated by the construction activities are likely to include C&D materials, general refuse and chemical waste.  Provided that these identified waste arising are handled, transported and disposed of using approved methods and that the recommended good site practice is adhered to, adverse environmental impacts are not anticipated.