9 waste management implications & land … · project administration handbook for civil ......

Drainage Services Department Agreement No. CE 41/2013 (EP)

Port Shelter Sewerage, Stage 3 – Sewerage Works at Po Toi O

Environmental Impact Assessment Studies - Investigation

Environmental Impact Assessment Report

IA13070/EIARpt v2.3 Cinotech

9-1

9 WASTE MANAGEMENT IMPLICATIONS & LAND CONTAMINATION

9.1 Introduction

9.1.1 This Chapter identifies the types of wastes that are likely to be generated during the

construction and operation of the Project, and evaluates the potential environmental

impacts that may result from these wastes.

9.2 Relevant Legislations, Standards & Guidelines

9.2.1 Reference has been made to the following Ordinances and Regulations which are

relevant to waste management and disposal:

The Waste Disposal Ordinance (Cap. 354) and subsidiary legislation such as the

Waste Disposal (Chemical Waste) (General) Regulation and Waste Disposal

(Charges for Disposal of Construction Waste) Regulation that set out

requirements for the storage, handling and transportation of all types of wastes.

Environmental Impact Assessment Ordinance (Cap. 499), Technical

Memorandum on Environmental Impact Assessment Process (EIAO-TM),

Annexes 7 and 15;

Public Health and Municipal Services Ordinance (Cap. 132) – Public Cleansing

and Prevention of Nuisance Regulation – control of disposal of general refuse;

Land (Miscellaneous Provisions) Ordinance (Cap. 28); and

Dumping at Sea Ordinance (Cap. 466).

9.2.2 Other relevant documents and guidelines are applicable to waste management and

disposal in Hong Kong include:

Code of Practice on the Packaging, Labelling and Storage of Chemical Wastes

(1992);

Development Bureau Technical Circular (Works) (TC(W)) No. 6/2010, Trip

Ticket System for Disposal of Construction & Demolition Materials;

Development Bureau TC(W) No. 8/2010 Enhanced Specification for Site

Cleanliness and Tidiness;

ETWB TC(W) No. 34/2002, Management of Dredged / Excavated Sediment;

ETWB TC(W) Nos. 22/2003 and 22/2003A, Additional Measures to Improve

Site Cleanliness and Control Mosquito Breeding on Construction Sites;

ETWB TC(W) No. 19/2005, Environmental Management on Construction Sites;

Project Administration Handbook for Civil Engineering Works, 2014 Edition

Section 4.1.3, Management of Construction and Demolition Material Including

Rock;

Works Bureau TC No. 2/93, Public Dumps;

Works Bureau TC No. 2/93B, Public Filling Facilities; and

Works Bureau TC Nos. 25/99, 25/99A and 25/99C, Incorporation of Information

on Construction and Demolition Material Management in Public Works Sub-

committee Papers.






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9.2.3 Legislations and guidelines related to land contamination are given below:

Environmental Impact Assessment Ordinance (Cap. 499), Technical

Memorandum on Environmental Impact Assessment Process (EIAO-TM),

Annex 19;

Waste Disposal (Chemical Waste) (General) Regulation (Cap 354C)

Dangerous Goods Ordinance (Cap 295)

Practice Guide for Investigation and Remediation of Contaminated Land;

Guidance Note for Contaminated Land Assessment and Remediation; and

Guidance Manual for Use of Risk-Based Remediation Goals (RBRGs) for

Contaminated Land Management.

Waste Management

9.2.4 The Waste Disposal Ordinance (WDO) prohibits unauthorised disposal of wastes.

Construction waste is defined as any substance, matter or thing that is generated from

construction work and abandoned, whether or not it has been processed or stockpiled

before being abandoned, but does not include any sludge, screenings or matter

removed in or generated from any desludging, desilting or dredging works. Under the

WDO, wastes can be disposed of only at designated waste disposal facilities.

9.2.5 Under the WDO, the Chemical Waste (General) Regulation 1992 provides regulations

for chemical waste control, and administers the possession, storage, collection,

transport and disposal of chemical waste. 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 waste.

9.2.6 Public Cleansing and Prevention of Nuisance Regulation provides control on illegal

tipping of wastes on unauthorised (unlicensed) sites.

9.2.7 The Land (Miscellaneous Provisions) Ordinance provides control on dumping of

public fill. The inert portion of construction waste (also called public fill) may be

taken to public fill reception facilities which are operated by the Civil Engineering and

Development Department (CEDD). The Land (Miscellaneous Provisions) Ordinance

requires that dumping licences be obtained by individuals or companies who deliver

public fill to public filling areas. The CEDD issues the licences under delegated

powers from the Director of Lands.

9.2.8 Under the licence conditions, public fill reception facilities will only accept inert earth,

soil, sand, rock, boulder, rubble, brick, tile, concrete, asphalt, masonry or used

bentonite. In addition, in accordance with Development Bureau Technical Circular

(Works) (TC(W)) No. 6/2010, the Public Fill Committee will advise on the acceptance

criteria (e.g. no mixing of construction waste, nominal size of the materials less than

250mm, etc.) for disposal of construction and demolition (C&D) materials at public

fill facilities.






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Construction and Demolition (C&D) Material

9.2.9 The current policy related to the disposal of C&D materials is documented in the

Works Branch TC No. 2/93, ‘Public Dumps’. C&D materials that are wholly inert,

namely public fill, should not be disposed of to landfill, but should be taken to public

filling areas for reuse.

9.2.10 Under the Waste Disposal (Charges for Disposal of Construction Waste) Regulation,

enacted in January 2006, 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 materials.

9.2.11 The ETWB TC(W) No. 19/2005 “Environmental Management on Construction Sites”

includes procedures on waste management requiring contractors to reduce the C&D

materials to be disposed of during the course of construction. The Project

Administration Handbook for Civil Engineering Works, 2014 Edition Section 4.1.3,

“Management of Construction and Demolition Material Including Rock” to enhance

the management of C&D materials, and to minimize its generation at source,

submission of C&D Materials Management Plan (C&DMMP) is not required for less

than 50,000 m3 C&D materials from Designated Projects and less than 300,000 m3

from non-Designated Projects. Under ETWB TC(W) No. 19/2005, the contractor is

required to prepare and implement an Environmental Management Plan (EMP) and

the Waste Management Plan becomes part of the EMP.

Chemical Waste

9.2.12 Under the Waste Disposal (Chemical Waste) (General) Regulations, all producers of

chemical waste must register with EPD and treat their wastes, either utilising on-site

plant licensed by 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 waste.

Marine Sediment

9.2.13 ETWB TC(W) No. 34/2002 Management of Dredged / Excavated Sediment stipulates

that marine sediment shall be disposed of at designated dumping ground in accordance

to its contamination level. The contamination level of the sediment is classified into

three categories (Cat. L, M, H) based on the Chemical Exceedance Levels (CEL)

shown in Table 9-1, which determines the disposal method.






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Table 9-1: Sediment Quality Criteria for the Classification of Sediment

Contaminants Lower Chemical

Exceedance Level

(LCEL)

Upper Chemical

Exceedance Level

(UCEL)

Metals (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)

Low Molecular Weight PAHs 550 3160

High Molecular Weight PAHs 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

* The contaminant level is considered to have exceeded the UCEL if it is greater than the value shown.

Category L: Sediment with all contaminant levels not exceeding the LCEL. The

material must be dredged, transported and disposed of in a manner

which minimizes the loss of contaminants either into solution or by

resuspension. 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.






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9.3 Assessment Methodology

9.3.1 The assessment of potential waste management implications includes the following

tasks:

Estimation of the types and quantities of waste arising;

Evaluation of potential impacts from the handling, collection, transportation and

disposal of waste; and

Proposal of mitigation measures for the waste management.

9.3.2 In order to identify and evaluate the potential contamination impacts associated with

the Project, a desktop study has been conducted to review the current and historical

land uses. Site inspections have been carried out to identify any contamination

hotspots and the site condition of the industrial operations, if any.

9.3.3 The assessment area covers the work boundary for the proposed sewage treatment

plant and proposed pipe alignment.

9.3.4 In addition, the following sources of information have been collected and reviewed:

Aerial photographs from Lands Department;

Available ground investigation reports

9.4 Estimation of Construction Waste Generation and Evaluation of Impact (Land-

based Works)

9.4.1 The top priority is to minimize any waste production. The amount of construction

waste has been minimized by designing the sewerage works with minimum land

requirement and adopting suitable construction method. As mentioned in Chapter 2 –

Project Descriptions, trenchless method will be adopted where pipes have to be laid

deep underground. This method involves excavation between two open ends without

uncovering the ground above. Trenchless method are capable to reduce the amount of

excavated materials when compared with open-cut methods.

9.4.2 The actual amount of construction waste depends upon the practice of the Contractor.

The preliminary estimation is shown below.

9.4.3 Referring to the detailed construction method in Chapter 2 – Project Descriptions,

major construction waste will be:

Construction and demolition materials

Chemical waste

Bentonite slurry

General refuse from workforce






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Construction and Demolition Materials (C&D Materials)

9.4.4 C&D materials can be divided into two categories:

i. Inert C&D materials (or public fill), e.g. soil, rock, concrete etc., which could be

reused on-site as filling materials or off-site as public fill at public fill reception

facilities, and

ii. Non-inert C&D materials (or C&D waste), e.g. timber, paper etc., which should

be reused or recycled as far as possible; landfill disposal should be considered as

the last resort.

9.4.5 On average, the expected daily production of inert C&D materials (or public fill) is

5.21m3. During construction phase, 7,506m3 waste would be generated, which will

comprise the following:

Soil and plant materials generated from slope cutting;

Soil and rocks from drilling for submarine outfall;

Broken concrete from excavation work for pipe laying;

Soil from excavation work for pipe laying; and

Unused building materials, e.g. cement, concrete.

9.4.6 Rock excavation at sewage treatment plant (STP) and HDD works at rocky shore will

generate 4,344m3 of low quality rock, at a rate of 11.9m3 per day.

9.4.7 Approximately 2,430m3 of rocks, broken concrete and soil can be reused for

backfilling of excavated trenches after pipe laying. Unused building materials can be

used in other construction sites.

9.4.8 Non-inert C&D materials (or C&D waste) from land-based works will be as follows:

Plant materials;

Metal and timber formwork;

Bamboo scaffolding; and

Material packaging, e.g. plastic, paper wraps.

9.4.9 A designated area shall be identified during the construction stage for onsite sorting of

C&D materials as far as possible. Sorted inert materials shall be sent to a public fill

reception facility for beneficial reuse, and the closest public fill reception facility is

located at Tseung Kwan O Area 137 Fill Bank. DSD shall enquire with the Public Fill

Committee on the availability of public fill reception facility and acceptability of the

inert material.

9.4.10 Metal, paper and plastic should be recycled or reused as far as possible. Timber and

dismantled bamboo scaffolding should be reused in other projects if the quality

remains satisfactory. Non-inert C&D materials (or C&D waste) which are not

recyclable or reusable should be disposed of at landfill, and the closest one is South

East New Territories Landfill. DSD shall enquire with the Environmental Protection

Department on the availability of landfill and acceptability of the waste.

9.4.11 No barging point or conveyor system for waste removal will be adopted.






9-7

Chemical Waste

9.4.12 Chemical waste that may arise during the construction of the Po Toi O Sewage

Treatment Works (PTOSTW) includes:

Paint, solvents and detergents in fabricating the STP;

Cleansing fluid, lubricating oil, scrap batteries and fuel in maintaining and

powering machinery; and

Empty containers of the above substances.

9.4.13 The amount of chemical waste generated will vary between Contractors based on the

number of plant equipment to be employed and the maintenance frequency. However,

it is expected to be limited (about 1m3 for the whole Project) due to small project scale.

9.4.14 Improper handling of the chemical waste may pose health impact on workers (e.g.

accidental ingestion), fire hazard and contamination of soil and water. The Contractor

shall register with EPD as a chemical waste producer. All chemical waste shall be

delivered to Chemical Waste Treatment Centre in Tsing Yi by licensed collectors for

treatment and disposal in strict compliance with the Waste Disposal (Chemical Waste)

(General) Regulations.

Bentonite Slurry

9.4.15 Bentonite will be used as drilling liquid during horizontal directional drilling for the

proposed submarine outfall. Cutting comprising broken rock and marine sediment will

be mixed with bentonite and drawn out of the drilled tunnel. After extraction from

bentonite, broken rock will be disposed of as public fill while marine sediment will be

removed for marine disposal. Reconditioned bentonite free from cutting will be reused

for drilling.

9.4.16 The contractor may consider not to reuse the spent bentonite for whatever reasons. The

quantity of bentonite to be disposed of will depend on contractor’s practice. The

estimated quantity is 5m3 after completion of the drilling works. The bentonite shall be

dewatered before disposal at public fill. Alternative disposal methods are

recommended under ProPECC PN 1/94 Construction Site Drainage. Bentonite shall

be dumped at marine spoil ground after obtaining a marine dumping license from EPD.

For disposal at public drainage system, the bentonite shall be treated up to effluent

standards for sewers, storm drains or the receiving waters as set out in the WPCO

Technical Memorandum.

General Refuse

9.4.17 General refuse refers to the waste generated by workers during daily operation, e.g.

food waste and packaging, metal cans, plastic bottles and office waste. The estimated

daily generation is about 0.34m3 and the total quantity for this Project is about 460m3.

9.4.18 Even though the quantity is small, sufficient rubbish bins or collection area should be

provided to maintain the hygiene and tidiness of the works site. Otherwise the waste

may be blown away by wind or washed into nearby watercourses or sea. In addition to

causing pollution problem, this may clog drainage system, resulting in flooding under






9-8

heavy rain. Littering with rubbish around is also unsightly and may attract pest and

bring odour nuisance. Recycle bins should also be provided to encourage recycling for

paper, metal and plastic. As the South East New Territories Landfill no longer receive

waste other than construction waste, the collected waste shall be removed to Island

East Transfer Station at regular interval for final disposal to West New Territories

Landfill.

Other Wastes (Human Waste)

9.4.19 Workers can use the public toilet in the middle of Po Toi O Village. Otherwise,

chemical toilets should be provided if necessary, which should be maintained regularly

by registered waste collectors.

9.4.20 With implementation of mitigation measures in Section 9.8, waste management

impact due to handling, collection, transportation and disposal of C&D materials,

chemical waste and general refuse is expected to be acceptable.

Table 9-2: Summary of Land-based Waste

Type of Waste

Quantity

(approx. m3) Handling and

Disposal Options Potential Route Reuse

On-

site

Dispose

Off-site Total

1. C&D Materials

(Total)

2430 5412 7842 A portion of inert C&D

materials (or public fill) will

be reused on-site for

backfilling.

Inert C&D materials (or

public fill) which cannot be

reused on-site will be

disposed to Tseung Kwan O

Area 137 Fill Bank.

Po Toi O Chuen Road

Clearwater Bay Road

Wan Po Road Tseung

Kwan O Area 137 Fill Bank

(About 1-2 truck trips/day) Inert C&D

Materials (excavated soil)

1840 1032 2872

Inert C&D

Materials (low quality rock)

300 4044 4344

Inert C&D

Materials (broken

concrete pavement)

290 0 290

Non-inert C&D

Materials (excluding

marine sediment)

0 336 336 To be disposed of at landfill

(the closest landfill is South

East New Territories

Landfill (SENT))

Po Toi O Chuen Road

Clearwater Bay Road

Wan Po Road SENT

(About 1 truck trip/day)

2. Chemical Waste 0 1 1 To be disposed to Chemical

Waste Treatment Centre

(CWTC)

Po Toi O Chuen Road

Clearwater Bay Road

Lung Cheung Road

Ching Cheung Road

Tsing Kwai Highway

Tsing Yi Road CWTC

(Dispose when required)

3. General Refuse 0 460 460 To be sent to Island East

Transfer Station (IETS) for

compaction,

containerization and dispose

at West New Territories

Landfill.

Po Toi O Chuen Road

Clearwater Bay Road

Tsueng Kwan O Road

Eastern Harbour Crossing

Island Eastern Corridor

IETS

(About 1 truck trip/day)






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9.5 Estimation of Construction Waste Generation and Evaluation of Impact

(Marine-based Works)

9.5.1 Dredging will be involved in diffuser installation at the mouth of Po Toi O bay.

According to EPD Marine Water Quality Report 2013, the sediment quality of the

station PS6 in Outer Port Shelter (see Figure 9-1) is within Lower Chemical

Exceedance Level (LCWL) as shown in Table 9-3 below.

Table 9-3: Sediment Quality at Station PS6

Contaminants PS6 Lower Chemical

Exceedance Level (LCEL)

Metals (mg/kg in dry weight)

Cd <0.1 1.5

Cr 24 80

Cu 11 65

Pb 30 40

Hg <0.05 0.5

Ni 18 40

Ag <0.2 1

Zn 64 200

Metalloid (mg/kg in dry weight)

As 5.9 12

Organic-non-PAHs (µg /kg in dry weight)

PCBs 18 23

Organic-PAHs (µg /kg in dry weight)

Low Molecular Weight PAHs 98 550

High Molecular Weight PAHs 32 1700

9.5.2 As part of site investigation conducted in 2015, sediment samples were collected at

the proposed diffuser location and its vicinity (SD1 and SD2) as shown in Figure 9-2.

Sediment was collected by vibrocoring down to the proposed dredging depth (4m).

Samples were collected at 4 depths (i.e. 0 – 0.9m, 0.9 – 1.9m, 1.9 – 2.9m and 3.0 –

3.9m below seabed) at each station. Chemical testing revealed that all samples

belonged to Category L according to ETWB TC(W) No. 34/2002 Management of

Dredged/Excavated Sediment.

9.5.3 For fulfilment of Section 3(i) of the Study Brief, Sediment Sampling and Testing Plan

(SSTP) has been submitted to EPD for agreement prior to commencement of the tests

for this EIA Study. This plan details the ranges of parameters to be analysed; the

number, type and methods of sampling; sample preservation; chemical and biological

laboratory test methods to be used.

9.5.4 The SSTP was approved by EPD on 4 January 2016 and sediment sampling was

conducted on 19 February 2016. Since the expected contamination level of the

sediment from the Project is low, sampling was proposed within a 200m 200m grid

for Tier II analysis. As the dredging work is highly localized within 50m 10m






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cofferdam, one sediment sampling station (SD3) was set near the proposed diffuser

location as shown in Figure 9-2. Surface sediment was collected by grab sampling

and then sent to a HOKLAS laboratory for testing. The sediment sample was also

confirmed to be of Category L. Category L materials being dredged, transported and

disposed must be handled carefully to minimize the loss of contaminants either into

solution or by resuspension.

9.5.5 The results are summarized in Table 9-4 and detailed in Appendix 9.1.

Table 9-4: Summary of Sediment Sampling and Testing Results

Station Location Easting Northing Depth Classification

SD1 Location of proposed

diffuser 848645 815745 4m Cat L

SD2 20m south of the

proposed diffuser 848640 815721 4m Cat L

SD3

Within proposed

cofferdam enclosed

area

848645 815779 Surface Cat L

9.5.6 Since SSTP and Sediment Quality Report (SQR) are only serve the purpose of

fulfilling the EIA Study for this Project under the EIAO, TM and Study Brief, separate

submissions (e.g. SSTP/SQR) to EPD's Territorial Control Office (TCO) will be

required when applying for the dumping permit under Dumping at Sea Ordinance

(DASO). The rationale for sediment removal/disposal will also need to be submitted

to the Marine Fill Committee (MFC) of Civil Engineering and Development

Department (CEDD) for agreement in accordance with ETWB TC(W) No. 34/2002

Management of Dredged/Excavated Sediment.

9.5.7 About 500m2 of marine sediment will be dredged, of which 5m2 will be occupied by

the diffuser (see Figure 9-2 for dredging boundary). In total, 1,200m3 of dredged

marine sediment will be generated. As the quantity of Category L sediment is far

below 50,000m3, the open sea disposal site shall be assigned by MFC/CEDD after

application of dumping permit under DASO. A maximum of four barge trips per day

for sediment disposal is anticipated.

9.6 Land Contamination

Historic Land Uses

9.6.1 Historical aerial photographs covering Po Toi O area were reviewed to evaluate any

land use changes associated with potential contamination implication within the

proposed work boundary demarcated in Figure 1-1. The oldest aerial photo available

dated back to 1945. Changes of land use observed are shown in the following table:






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Table 9-5: Historical Change in Po Toi O and its vicinity

Year Observation

1945

Very few houses in Po Toi O;

Agriculture lands were found at where the golf course and Fairway Vista are

currently located;

Few boats parking in Po Toi O Bay; &

A pier has been established on/before 1945

1963 The pier was expanded; &

Gradually increased in the number of houses in Po Toi O

1973 Fish rafts were erected, more settlement

1979

Site clearance for the construction of Tai Au Mun Road, Po Toi O Chuen

Road and Clearwater Bay Country Club; &

Gradual increase in the number of houses in Po Toi O, and the number of

fish rafts in Po Toi O Bay

1982

Cut-slope formed at the proposed STP location;

Construction of footpath above the cut slope; &

Concreting of open space outside Tin Hau Temple

1986 Well-developed village in Po Toi O and Tai Wong Kung; &

Obvious increase in the number of fish rafts in Po Toi O Bay

1987 Site clearance for the construction of Fairway Vista and its access road

1996 Site clearance for the construction of Seacrest Villas

2000 Construction of a second pier at Po Toi O

2014 No noticeable change in Po Toi O since 2000.

9.6.2 Based on the aerial photos, Po Toi O was historically used for residential (village),

agriculture, boat shelter, fish farming, religious and golfing uses. No boat factory,

repairing workshop or other industrial activity that may cause land contamination was

identified. Representative photos are provided in Appendix 9.2. No activity that has

risk of land contamination was observed.

Existing Land Use

9.6.3 Site inspection was carried out on 20 February 2014 to identify any contamination

hotspots within the proposed work boundary. The current land use is for residential

(village), fish farming, religious, golfing, dining, tourism and boating uses (inspection

photos of current land use are presented in Appendix 9.3). According to AFCD, there

is also leisure fishing business on fish rafts. No boat factory, repairing workshop or

other industrial activity was observed or reported.

9.6.4 No land contamination report was found in the Po Toi O area. Enquiry has been

sought from Environmental Protection Department (EPD) on any historic record on

chemical waste producers and spillage/leakage incidences in Po Toi O, and from Fire

Services Department (FSD) on dangerous goods licence and spillage/leakage of

dangerous of goods. Both departments confirmed neither records were found (letter

attached in Appendix 9.4).






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9.6.5 As there is no record of industrial land use or leakage of chemical in Po Toi O, land

contamination within the proposed work boundary is highly unlikely.

9.7 Estimation of Operational Phase Waste Generation and Evaluation of Impact

Sludge

9.7.1 During the operational phase, sludge with low dry solid content will be produced after

the sewage treatment. The normal practice is to dewater the sludge to a dry solid

content of 20~30% for disposal at landfills. However, as the estimated daily

production of the sludge is 5.3m3, it was considered not cost-effective to expand the

footprint of the proposed sewage treatment plant to accommodate a sludge dewatering

facility. It is proposed that the sludge with about 7% dry solid content will be removed

to a nearby STP for dewatering every 2 days by a sludge tanker. The receptor STP will

be identified before operation of the PTO STP.

9.7.2 The new Sludge Treatment Facility in Tuen Mun is in operation and should be able to

receive the dewatered sludge by the time the STP runs in 2020. Therefore, no

significant impact is expected due to operation of the STP.

9.7.3 Sludge tankers will be used to transport the sludge for treatment. The tanker will park

inside the STP building and sludge will be pumped by coupling. The odourous gas

will be confined within the STP which will be kept under negative pressure. The gas

will be drawn to a deodouring system for treatment before release into the atmosphere.

As the transfer process will be carried out in enclosed environment and in low

frequency, no odour or traffic impact is expected on the surrounding sensitive

receivers during handling of the sludge.

Solid Waste

9.7.4 Screening will be carried out at the sewage inlet to remove large solid matters such as

faeces, paper, sand or even plastic bags. The debris produced from the screening

process will be removed regularly to maintain the efficiency of the screen and the solid

matters will be disposed of at landfill inside sealed containers to contain odour. The

production rate is expected to be 0.25m3 per day.

9.7.5 In addition to solid waste from sewage treatment, small amount of general refuse will

also be generated from staff, and this shall be dumped at the relocated FEHD refuse

collection point or disposed of at landfill together with the debris.

Chemical Waste

9.7.1. Regular chemical cleaning of the MBR membranes will be required to prevent

membrane fouling and to maintain the membrane performance. MBR would be

periodically cleaned every 3~6 months. The tanks will be disinfected by sodium

hypocholorite. Sodium hypochlorite and/or oxalic acid would be adopted for the

removal of organic and inorganic deposits. The cleaning process will take place in-situ

on the permeate side without removal of membrane. The deposits will dissolve in the

sewage and be treated by the MBR system. The unused chemical will follow the






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sewage flow in the MBR system, neutralized by hydrogen chloride and eventually be

discharged with treated effluent at the diffuser. As the used chemicals will be treated

and amount should be small when compared with the quantity of effluent, the water

quality impact due to MBR cleaning will not be significant.

9.7.2. Used filters in the deodourizing unit will be replaced and disposed of as solid waste at

landfill. The frequency of removal will be decided in the detailed design stage.

9.7.3. Emergency generator will be brought to the STP in case of power failure. Diesel will

be used as power fuel and the used oil drum will become chemical waste. As dual-feed

power from power company will be provided, it is anticipated that only under very

rare occasion will both primary and secondary power be failed such that emergency

generator will be activated. The quantity of diesel required will be dependent on the

time of restoration of the plant and therefore cannot be quantified. However, given the

highly infrequent occurrence of the emergency situation, the quantity of used oil

drums should be insignificant.

9.7.4. All chemical waste shall be properly stored, labelled and removed by licensed waste

collectors as per Waste Disposal (Chemical Waste) (General) Regulation.

9.8 Mitigation Measures

9.8.1 Careful planning before construction work and close monitoring will be crucial to

prevent performing unnecessary works, resulting in extra waste.

Construction Phase

9.8.2 Handling, storage, collection and disposal of waste shall be proposed in accordance

with Waste Disposal Ordinance. Good site practices shall be implemented to minimize

undesirable nuisance:

C&D Materials

The Contractor shall identify suitable location for temporary stockpiling

(tentatively within construction site). The stockpile should be covered by

tarpaulin or other water-resistant fabric. This can prevent the waste from being

blown away by wind or washed into watercourses/sea/drainage system under

heavy rain.

Waste sorting area should be provided as far as possible to separate out reusable,

recyclable wastes and/or public fill. Dumping at landfill should be considered as

last resort.

Sorted waste should be stored separately at designated locations.

Cover waste materials with tarpaulin or in enclosure during transportation

As Po Toi O has little flat and vacant land for stockpiling the waste onsite for

disposal offsite, the contractor should identify and agree with local residents on

commencement of the works for a proper storage/sorting site.






9-14

Dump trucks should be near fully loaded with excavated materials before

departure from the construction site. Frequent movement of traffic is a source of

annoyance and increases the chance of accidental leakage.

However, the trucks should not be overloaded and the cover should be closed to

enclose the excavated materials during movement.

Careful planning and estimation should be made to avoid over-ordering and

therefore wastage of construction materials.

Adopt durable materials for formworks and scaffolding (e.g. steel) for future

reuse.

Odour-emitting waste should be stored in tight containers.

Reduce water content in wet spoil generated from piling work by mixing with

dry materials. Only dispose treated spoil with less than 25% dry density to

Public Fill Reception Facilities.

Chemical Waste

Chemical waste should be stored at designated chemical waste storage area with

bunds on impermeable ground. Roof and locks should be provided if stored

outdoor. Alternatively, cabinet or cupboard with spill trays can be used if the

quantity of waste is small.

Chemical waste should be labelled clearly in accordance with Code of Practice

on the Packaging, Labelling and Storage of Chemical Wastes to alert workers on

hazard during handling and storing:

o Store chemical waste with suitable containers. Seal and maintain the

container to avoid leakage or spillage during storage, handling and transport

o Label chemical waste containers in both English and Chinese with

instructions in accordance to Schedule 2 of the Waste Disposal (Chemical

Waste) (General) Regulation

o The container capacity should be smaller than 450 litres unless agreed by

the EPD

Compatible containers should be used for storing specific chemical waste to

prevent leakage/spillage (e.g. resistant to corrosive chemicals). Checking of the

integrity of the containers before and during use is required.

The Contractor should be registered as a Chemical Waste Producer with EPD

and engage licensed chemical waste collectors for disposal under the Waste

Disposal (Chemical Waste)(General) Regulation.

Comply with the requirements of the chemical storage area:

o Store only chemical waste and label clearly the chemical characters of the

waste

o Have at least 3 sides enclosed and protected from rainfall with cover

o Provide sufficient ventilation

o Have impermeable floor and has bunds to contain 110% of the capacity of

the largest container or 20% of the total volume of the stored waste in the

area, whichever is larger

o Adequately spaced incompatible materials

Transfer used lubricants, waste oils and other chemicals to oil recycling

companies, if possible, and empty oil drums for reuse or refill. No direct or

indirect discharge is permitted






9-15

Hire licensed chemical waste disposal contractors for waste collection and

removal. Dispose chemical waste at the approved CWTC at Tsing Yi or other

licensed facility

General Refuse

Sufficient rubbish bins should be provided at regular interval for collection of

general refuse.

Recycle bins should be provided to encourage recycling of paper, plastic and

metal cans.

Collected waste should be removed from the construction site by registered

collectors regularly.

Good Site Practices

Prepare and implement a site specific Waste Management Plan (WMP) as part

of Environmental Management Plan (EMP) in accordance with ETWB TC(W)

No. 19/2005. Detail waste management method in the form of avoidance, reuse,

recovery, recycling, storage, collection, treatment and disposal according to the

recommendations on the EIA and EM&A Manual. It should be approved by the

engineer’s representative and regularly reviewed.

Apply for relevant waste disposal permits in accordance with the Waste Disposal

Ordinance (Cap. 354), Waste Disposal (Charges for Disposal of Construction

Waste) Regulation (Cap. 345) and the Land (Miscellaneous Provisions)

Ordinance (Cap. 28), Dumping at Sea Ordinance (Cap. 466).

A trip ticket system should be implemented to monitor the flow of waste from

the construction site to public fill reception facilities/landfill/chemical waste

treatment facilities/recycler.

Works schedule will be well planned to minimize the excavation work area in

any time.

Should chemical toilet be provided, the sewage shall be regularly cleaned by

registered contractor.

Provide training to workers on site cleanliness, waste management (waste

reduction, reuse and recycle) and chemical handling procedures

Maintain drainage systems, sumps and oil interceptors

Provide sufficient waste collection points and regular waste removal

Minimize wastage through careful planning and avoiding over-purchase of

construction materials

Store waste materials properly as follows:

o Avoid contamination by proper handling and storing waste

o Prevent erosion by covering waste or applying water spray

o Maintain and clean storage area regularly

o Sort and stockpile different materials at designated location to enhance

reuse

Hire licensed waste disposal contractors for waste collection and removal.

Dispose waste at licensed waste disposal facilities

Provide wheel washing at construction site exit to clean the vehicle body and

wheel






9-16

Organize training and reminders to site staff on waste minimization through

avoidance and reduction, reusing and recycling

Bentonite

Used bentonite shall be reconditioned onsite and reused as far as practical to

minimize wastage. If this is deemed not viable, the used bentonite shall be

delivered offsite for reconditioning.

Marine Sediment

Since only Category L sediment (i.e. uncontaminated sediment) was identified,

dredged marine sediment will be transported by a barge to dispose of at

designated marine dumping ground by open sea dumping according to ETWB

TCW No. 34/2002 Management of Dredged/Excavated Sediment.

Operational Phase

9.8.3 Sludge will be delivered by sealed sludge tanker for treatment at Sludge Treatment

Facilities.

9.8.4 Debris from screening process and general refuse should be stored within the STP in

sealed container and be disposed of at landfill regularly.

9.8.5 Worn filters and MBR membrane shall be stored and labelled as in construction phase.

Chemical waste shall be treated at chemical treatment facility by licensed contractor.

9.9 Residual Impact

9.9.1 With proper implementation of the mitigation measures, no residual impact is

anticipated for waste generated from construction works and operation of PTOSTW.

9.10 Environmental Monitoring and Audit

9.10.1 The Contractor should prepare a Waste Management Plan in accordance with ETWB

TC(W) No. 19/2005 Waste Management on Construction Site, which details the

expected amount of different types of wastes generated in the coming month and year

and updates at regular intervals. The actual waste usage should be recorded monthly.

Waste handling, storage and removal methods should also be proposed in the WMP

and be reviewed the effectiveness at regular intervals. Training should be provided to

all staff to ensure that they are aware of the practice, in particular in chemical waste

handling (e.g. understanding of hazard labels and emergency procedures).

9.10.2 Regular site inspection shall be carried out during construction phase to check whether

the proposed mitigation measures have been properly implemented and to evaluate the

effectiveness.






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9.10.3 No EM&A is proposed for Operational Phase.

9.11 Conclusion

9.11.1 During construction phase, major C&D materials will be composed of rock and soil

from slope cutting for STP construction. Other waste includes chemical waste from

maintenance of plant equipment, used bentonite from drilling works, marine sediment

from dredging works and general refuse from workforce.

9.11.2 Sediment Sampling and Testing Plan (SSTP) has been submitted to EPD as required

under the Study Brief. Sedimentary Quality Tests of sediment at and near the dredging

point showed that the materials were classified as Category L. According to ETWB

TC(W) No. 34/2002 Management of Dredged/Excavated Sediment, Category L

materials shall be disposed at open sea disposal site assigned by the Marine Fill

Committee (MFC).

9.11.3 Since SSTP and SQR are only serve the purpose of fulfilling the EIA Study for this

Project under the EIAO, TM and Study Brief, separate submissions (e.g. SSTP/SQR)

to EPD's TCO will be required when applying for the dumping permit under DASO.

The rationale for sediment removal/disposal will also need to be submitted to the

Marine Fill Committee (MFC) for agreement in accordance with ETWB TC(W) No.

34/2002 Management of Dredged/Excavated Sediment.

9.11.4 Operation of sewage treatment plant will generate sludge, debris from screening, worn

filter in deodouring unit and general refuse from staff.

9.11.5 The waste shall be handled and disposed of properly to prevent causing damage to the

environment, e.g. water pollution, odour nuisance and hygiene issue. With

implementation of the recommended measures and site practices, impact due to waste

management is expected to be acceptable.

9.11.6 Based on historical aerial photos, land use history, site inspection and information

from EPD and FSD, it is concluded that land contamination within the proposed work

boundary is highly unlikely.

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