7                    WASTE MANAGEMENT ImPact

 

Introduction

 

7.1              This section identifies the types of wastes that are likely to be generated during the construction and operational phases and evaluates the potential environmental impacts that may result from these waste arisings.  The main solid waste management implications are related to dredged marine sediment from the dredging works for the approach channel and foundation of the jetty and catwalk.  Mitigation measures and good site practice, including waste handling, storage and disposal will be recommended with reference to the applicable waste legislation and guidelines.

 

Environmental Legislation and Standards

 

7.2              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 Process (EIAO TM), respectively.

 

7.3              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).

 

Waste Management

 

7.4              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.

 

7.5              The Public Cleansing and Prevention of Nuisance By-Laws provides control on illegal tipping of wastes on unauthorised (unlicensed) sites.

 

Marine Sediment

 

7.6              The WBTC No. 3/2000 sets out the new management framework for dredged / excavated sediment. This Technical Circular outlines the new procedures to be followed in assessing and classifying sediment and explains the marine disposal arrangement for the classified material.  The construction of the Project is scheduled to commence in January 2003 and, therefore, the requirements of WBTC No. 3/2000 should be followed.  The sediment quality criteria for the classification of sediment are presented in Table 7.1. Dumping permits from EPD are required for marine disposal of dredged materials.

 

 

Construction and Demolition (C&D) Materials

 

7.7              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 individual 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.

 

7.8              In addition to the Works Branch Technical Circular (WBTC), 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 of inert material (that is, 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 (that is, C&D waste) sent to landfill for final disposal.

 

Assessment Methodology & Criteria

 

General

 

7.9              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 and operational phases of the Project 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 and wastewater discharges; and

·           Impacts on the capacity of waste collection, transfer and disposal facilities.

 

Marine Dredged Materials

 

7.10          Surface (grab) sample of marine sediment was collected on 7 February 2002 for laboratory testing of contaminants to characterise the sediment quality within the proposed area of dredging for the purpose of the EIA Study. The location of the sampling point is presented in Figure 7.1. The methodology for the sediment quality characterisation survey was agreed with EPD.

 

7.11          The sediment sample 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: total polychlorinated biphenyls (PCBs) and polyaromatic hydrocarbons (PAHs).

 

7.12          The sediment quality criteria under the new management and classification system for dredged sediments destined for marine disposal are listed in Table 7.1 below.

 

Table 7.1  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

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

Note:      LCEL –   Lower Chemical Exceedance Level

                            UCEL –  Upper Chemical Exceedance Level

 

7.13          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.

7.14          For projects with disposal requirements of less than 50,000 m3 Category L sediment, the allocation of sediment disposal space had been delegated to DEP in accordance with WBTC No.3/2000.

 

Baseline Conditions

 

Existing Sediment Characteristics

 

7.15          The marine sediment quality analysis results of chemical testing, as compared with the sediment quality criteria for the classification of sediment, are presented in Table 7.2.

 

7.16          The chemical testing results indicate that Category L sediments were found at the project area and therefore the sediments are suitable for open sea disposal.

 

Table 7.2     Results of Sediment Quality Analysis

 

LMW

HMW

Total PCBs

Metals

Overall Category

PAHs

PAHs

mg/kg

ug/kg

ug/kg

ug/kg

Cd

Cr

Cu

Ni

Pb

Zn

Hg

As

Ag

<55

<170

<3

0.4

28

36

20

44

110

0.06

8

<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.

 

Identification of Potential Sources of Impact

 

Construction Phase

 

7.17          The construction activities to be carried out for the proposed Project will result in the generation of a variety of wastes which can be divided into distinct categories based on their composition and ultimate method of disposal.  The identified waste types include: 

 

·          marine dredged sediment; and

·          C&D materials.

 

7.18          The nature of each type of waste arising is described in the following section, together with an evaluation of the potential environmental impacts associated with these waste arisings.

 

Marine Dredged Sediment

 

7.19          It is proposed that dredging will be carried out for the jetty and catwalk foundation and the approach channel. The total volume of dredged sediment for the Project is estimated to be approximately 5,550 m3. The potential environmental effects of the removal of these sediments on water quality have been assessed and presented in Section 3 of this Report.

 

7.20          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 that minimises the loss of contaminants either into solution or by resuspension. Mitigation measures to minimise potential environmental impacts are recommended in Section 7.27. It is anticipated that, with the implementation of mitigation measures, no unacceptable impacts will result from the transportation and disposal of the dredged sediment.

 

Construction and Demolition Materials

 

7.21          Excavated material will be generated from the footpath extension from excavation at the proposed footings of the footpath.  The excavated material is anticipated to consist of sandy deposits, pebbles and rocky boulders.  In view of the small scale of the land-based construction works, the volume of construction and demolition (C&D) material requiring off-site disposal to public filling areas is anticipated to be minimal, approximately 10 m3.

 

7.22          C&D material will also be generated from the demolition of the existing jetty. The C&D material is anticipated to consist of broken concrete and reinforcement. The estimated volume of C&D material is approximately 150 m3 and will require off-site disposal to public filling areas. Since the construction activities will be located within the Marine Park, improper management of C&D materials may introduce debris and pollutants to the marine waters, and therefore strict control over waste management practices during the construction works will be required.  Release of these potential pollutants into the marine waters should not be permitted as any deterioration in water quality is likely to have adverse impacts on the Chinese White Dolphin and other marine fauna.

 

Operation Phase

 

7.23          During the operation phase of the jetty, the only anticipated waste arising is marine dredged sediment from maintenance dredging of the approach channel which is likely to be required every 5 years. Dredging of sediments deposited within the approach channel would be required to maintain sufficient water depth for the government department’s vessels to berth at the jetty.

 

7.24          The volume of dredged sediment from maintenance dredging is expected to be approximately 750 m3 each time. Impacts arising from the transportation and disposal of the dredged sediment would be similar to the construction phase. The recommended mitigation measures for waste management implications associated with the construction phase dredging are also applicable to the maintenance dredging.

 

Mitigation Measures

 

Construction Phase

 

                Marine Sediments

 

7.25          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).

 

7.26          The dredged marine sediments will be loaded onto barges and transported to the designated disposal site.  Category L sediments were found at the project area and therefore the sediments are suitable for open sea disposal.  EPD have advised that the sediment could be dumped at the South Cheung Chau marine disposal ground.  At this stage in the engineering design and based on the sediment sampling results, it is estimated that some 5,550 m3 of sediments will require open sea disposal. In accordance with the WBTC No. 3/2000, the material must be dredged, transported and disposed in a manner which minimizes the loss of contaminants either into solution or by resuspension.

 

7.27          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.

 

Good Site Practices and Waste Reduction Measures

 

7.28          Appropriate waste handling, transportation and disposal methods for all waste arisings generated during the construction works should be implemented to ensure that construction wastes do not enter the marine waters of the Sha Chau and LKC Marine Park

 

7.29          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 procedures;

·          high standards of waste management should be observed on the works vessels and barges to ensure that no waste arisings or fuel/diesel oils are disposed to the surrounding marine waters;

·           careful control should be exercised during the demolition works and strict waste management procedures will be required to ensure that no C&D materials and machinery fuels enter the marine waters at the site;

·           no stockpiles of construction material should be permitted on Lung Kwu Chau Island;

·           all wastes, unused construction materials and construction equipment should be removed from Lung Kwu Chau Island after the works are completed;

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

·           in order to monitor the disposal of C&D materials at public filling areas, and to control fly-tipping, a trip-ticket system should be included as one of the contractual requirements. One may make reference to WBTC No. 5/99 for details.

 

7.30          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: 

·           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  use of construction materials carefully to minimise amount of waste generated and avoid unnecessary generation of waste.

Operation Phase

 

7.31          The recommended mitigation measures for the transportation and disposal of dredged marine sediments from the construction phase dredging should also be implemented as appropriate during maintenance dredging.

 

Evaluation of Residual Impacts

 

7.32          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 and operation of the proposed Project.

 

Environmental Audit

 

7.33          Waste management will 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 the recommended 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 at the construction stage.

 

Conclusion

  

7.34          A review of the sediment quality data from the sediment characterisation survey indicates that the sediments to be dredged at the project area are classified as Category L and therefore the sediments are suitable for open sea disposal. With the implementation of the recommended mitigation measures and management procedures in accordance with the requirements of WBTC No. 3/2000, no residual impact is predicted.

 

7.35          Other wastes generated by the construction activities are likely to include C&D material from demolition works for the existing jetty and the footpath extension.  Provided that these identified waste arisings are handled, transported and disposed of using approved methods and that the recommended good site practices are strictly followed, adverse environmental impacts are not anticipated during the construction works. High standards of waste management should be observed to ensure that no waste arisings enter the marine waters of the Sha Chau and LKC Marine Park.

 


[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”.