AXIS - Environmental Protection Department
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AXIS Environmental EXTENSION TO TYTL l08RP PROPOSED RECLAMATION AND RELOCATION OF UNITED FLOATING DOCK TO TSING YI ENVIRONMENTAL IMPACT ASSESSMENT FINAL REPORT j
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Transcript of AXIS - Environmental Protection Department
AXIS
Environmental
EXTENSION TO TYTL l08RP
PROPOSED RECLAMATION AND
RELOCATION OF UNITED FLOATING
DOCK TO TSING YI
ENVIRONMENTAL IMPACT
ASSESSMENT
FINAL REPORT
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AXIS
-'-- / Environmental
E.P'O. Library HONGKONG UNITED DOCKYARDS LTD.
EXTENSION TO TYTL l08RP
PROPOSED RECLAMATION AND
RELOCATION OF UNITED FLOATING
DOCK TO TSING YI
ENVIRONMENTAL IMP ACT
ASSESSMENT
FINAL REPORT
JULY 1996
AXIS Environmental Consultants Ltd.
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HONGKONG UNITED DOCKYARDS LTD
Extension to TYTL 108RP
Proposed Reclamation and Relocation of
United Floating Dock to Tsing Yi
Environmental Impact Assessment
Contents
LIST OF FIGURES
LIST OF TABLES LIST OF ApPENDICES
1.0 INTRODUCTION
1.1 STUDY OVERVIEW
1.2 THE NEED FOR THE DEVELOPMENT
Final Report
July 1996
1.3 PURPOSES AND OBJECTIVES OF THE ENVIRONMENTAL ASSESSMENT REpORT
2.0 PROJECT DESCRIPTION
2.1 PROJECT HISTORY
2.2 PHASE 1 - RECLAMATION AND SITE PREPARATION
2.3 PHASE 2- DOCK OPERATION /
3 BASELINE CONDITIONS
3.1 WATER QUALITY
3.2 SEDIMENT QUALITY
3.3 ECOLOGY
3.4 TRAFFIC
3.5 NOISE
3.6 AIR QUALITY
3.7 PLANNING CONTEXT AND LAND USE
4.0 PHASE 1 - CONSTRUCTION IMPACT ASSESSMENT
4.1 INTRODUCTION
4.2 POTENTIAL IMPACTS OF EXCAVATION
4.3 IMPACTS OF RECLAMATION
4.4 IMPACT OF "RELOCATION PHASE
5.0 PHASE 2 - OPERATIONAL PHASE IMPACTS
5.1 INTRODUCTION
5.2 IMPACT OF PROCESS WATERS ON THE MARINE ENVIRONMENT
AXIS Environmental Consultants Ltd AXT/5/3//92-000 Contents Page 1
Hongkong United Dockyards Ltd - Extension to TYTL I08RP Proposed reclamation and relocation of United Floating Dock. Tsing Yi Environmental Impact Assessment - Final Report
5.3 MITIGATION OF IMPACTS ARISING FROM PROCESS WATERS
5.4 OTHER IMPACTS
6 LICENCE REQUIREMENTS
6.1 INTRODUCTION
6.2 AIR POLLUTION CONTROL - ApPROVAL FOR THE INSTALLATION OF DIESEL GENERATORS
6.3 WATER POLLUTION CONTROL ORDINANCE - ApPLICATION FOR A DISCHARGE LICENCE.
6.4 WASTE DISPOSAL ORDINANCE - REGISTRATION AS A CHEMICAL WASTE PRODUCER, COLLECTOR
AND TRANSPORTER.
6.5 PESTICIDE CONTROL ORDINANCE - PERMIT TO USE TBT BASED PAINTS
7.0 ENVIRONMENTAL MONITORING AND AUDIT
7.1 INTRODUCTION
7.2 TECHNICALIPERSONNEL REQUIREMENTS
7.3 CONSTRUCTION PHASE MONITORING
7 .4 OPERATIONAL PHASE MONITORING
7.5 ENVIRONMENTAL AUDIT
8 CONCLUSIONS
8.2 RECOMMENDATIONS
REFERENCES
APPENDICES
AXIS Environmental Consultants Ltd AXTI5J3/192-000 Contents Page 2
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Hongkong United Dockyards LId - Extension to TYTL l08RP Proposed reclamation and relocation of United Floating Dock, Tsing Yi Environmental Impact Assessmenl- Final Report
LIST OF ApPENDICES
Appendix 1
Appendix 2
Appendix 3
Appendix 4
Appendix 5
Appendix 6
Appendix 7
Appendix 8
Appendix 9
Works branch Technical Circular No 10/95
Current Discharge Licence for United in the North West Water Control Zone
Western Buffer Water Control Zone - Water Quality Objectives and Effluent Discharge Requirements.
Literature Review of the Chemistry, Impacts and Controls for TBTs
HUD Shipyard Plume Studies
EPD Technical Circular No 1-1-92
Analytical Procedures for TBTs
Correspondence with Transport Department regarding TIA
Letter of Commitment from HUD to implement water collection and treatment system.
Appendix 10 Comments and Responses on the draft EIA Report
AXIS Environmental Consultants Ltd AXT15J3/J92-000 Contents Page 4
Hongkong United Dockyards Ltd - Extension to ITTL 108RP Proposed reclamation and relocation of UnUed Floating Dock. Tsing Yi Environmental Impact Assessment - Final Report
LIST OF FIGURES
Figure 1.1 Site Location
Figure 1.2 Proposed Area For Reclamation and Dock
Figure 2.1 Cross Sectional And Plan View of United Dock
Figure 2.2 Photographs of Existing Site and United
Figure 2.3 Current and Proposed Location Of Submarine Cable
Figure 2.4 Reclamation, Mooring and Dredging Arrangements
Figure 2.5 Cross Section of Blockwork Sea Wall
Figure 3.1 Location of Nearest Sensitive Receivers
Figure 3.2 Locations ofVibrocores and Grab samples for Sediment Survey
Figure 3.3 Planning Context of Site and Surroundings
Figure 5.1 TBT Contamination in Sediment around United, Yam 0 Wan
Figure 5.2 Sampling plan for sediment sampling around United and Taikoo
Figure 5.3 Plume dispersion under Scenario 1
Figure 5.4 Plume dispersion under Scenario 2
Figure 5.5 Plume Dispersion under Scenario 3
Figure 5.6 Chinese White Dolphin Sightings, June 1990 - August 1991
Figure 5.7 Preliminary Design for Collection of Wash waters
LIST OF TABLES
Table 3.1
Table 3.2
Table 3.3
Table 3.4
Table 5.1
Table 5.2
Table 7.1
Sediment Quality in Grab Samples taken from proposed mooring site, Tsing Yi
Results from Vibrocore Survey
TBT Concentration at HUD shipyard and Toxicity, 1994
Hong Kong Air Quality Objectives
Quality of Process Waters Discharged from the Dock
Tributyl tin in waters around Floating Docks in Yam 0 Wan.
Water Quality Monitoring Event Contingency Plan
AXIS Environmental Consultants Ltd AXTJ5J3/J92-000 Contents Page 3
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INTRODUCTION
SECTION 1
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1.0
1.1
1.2
1.3
INTRODUCTION
STUDY OVERVIEW
Hongkong United Dockyards Ltd (HUD) have commissioned Axis Environmental to undertake an Environmental Impact Assessment (EIA) for the proposed project. The proposed project is to relocate the 40,000 ton lifting capacity floating dock "United" from her existing location Yam 0 Wan north of Lantau Island to a new location off the dockyard premises at Tsing Yi Island, a short distance from HUD's 24,000 ton lifting capacity floating dock "Whampoa" which has been moored there since 1988. The findings of this assessment are presented in this report and supplement the EIA undertaken for the mooring and operation of United at Yam 0 Wan (Axis, 1994 &1995).
The proposed site lies within an industrial area on the south-west of Tsing Yi island, Hong Kong (Figure 1.1). The project site is adjacent to HUD's land based facility and the project will involve the extension of lot TYTL 108RP by the formation of a small reclamation of some 11,640m2 (Figure 1.2). The reclaimed land together with existing land would form an area of 14, 858 m2
• The purpose of the reclamation is mainly to gain access to the floating dock "United" once relocated. The timing of this project is of importance for safety reasons as the dock can only be relocated out of a typhoon season.
THE NEED FOR THE DEVELOPMENT
The relocation of the dock to Tsing Yi Island will enable land access to United bringing very significant commercial, productivity and safety benefits to the company. Improved efficiency of operations on the dock will be a direct result of reduced travelling time for workers; reduced distances over which waste and supplies must be transported; and improvements to the safety on the dock for workers who may require emergency services.
Environmental monitoring under the EM&A and Water Pollution Control Ordinance (WPCO) requirements has indicated that the dock is having adverse impacts on the marine environment in its current location, adding to the impact of the five other docks in the area. The relocation will provide the opportunity to significantly reduce the environmental impacts of the floating dock operations, as described below, since a land based operation offers the potential to collect and treat contaminated washwaters which would normally be discharged directly to the marine environment. The increased efficiency of the dock will enable HUD to decommission their older dock, Taikoo, which will soon reach the end of her useful life, thus ending all of HUD's operations at Yam 0 Wan and significantly reducing environmental impacts in this area.
PURPOSES AND OBJECTIVES OF THE ENVIRONMENTAL ASSESSMENT REPORT
The aim of this Environmental Impact Assessment (EIA) is to provide an assessment of the potential impacts which could arise from the proposed reclamation works and the relocation of the floating dock to Tsing Yi. These issues were identified in the Inception Report (Axis, December 1995) and have been described and assessed in terms of their significance in this report.
The key issues are:
• Impacts arising from dredging and excavation on the marine environment;
• Impacts of reclamation on the marine environment;
• Contaminants, such as Tributyl tin (TBT) released into the marine environment;
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Hongkong United Dockyards Ltd - Extension to TYTL I08RP Proposed reclamation and relocation of United Floating Dock. Tsing Yi Environmental Impact Assessment - Final Report
• Traffic Impacts
Also, impacts relating to noise and air quality require consideration due to the fact that the proposed project is land based and there is greater potential for impacts on sensitive receivers once the dock is brought to the shore adjacent to HUD's shipyard facility at Tsing Vi.
Section 2 of the report describes the project in terms of the proposed construction work (Phase I) and the subsequent operation of the dock at Tsing Yi (Phase 2). Section 3 provides a description of the baseline conditions which could be affected by the proposed development site. Due to the nature of the project this has focused on the marine environment but includes ecology, noise and air together with planning context ofthe site.
Due to the fact that potential impacts are inter-related the report has been divided so that these issues can be discussed together. The impact assessment has best been divided into two separate sections; Phase 1 impacts and Phase 2 impacts rather than considering each key issue separately. Section 4, therefore, assesses the key impacts associated with the proposed works during the construction phase of the study. Wherever possible, suggestions for impact mitigation have been made.
Section 5 provides an assessment of impacts associated with the operation of the dock, due to the nature of activities this largely focuses on impacts of discharge waters on the marine environment. Impacts are also compared to the existing situation.
Section 6 outlines the licence requirements for the dock and Section 7 sets out a preliminary plan for Environmental Monitoring and Audit. EM&A is recognised as being a key requirement to allowing the dock to operate and therefore this will be developed further in the form of a stand alone manual following consultation with EPD. Finally, the main conclusions of the EIA are presented in Section 8.
Following endorsement of this EIA, it will be necessary for HUD to submit the related rezoning request to the Town Planning Board for approvaL HUD is also required to apply for a land grant. Only after carrying out necessary.gazetting procedures, i.e. under the Town Planning Ordinance (if the Town Planning Board approve the rezoning request) and the Foreshore and Sea-bed (Reclamations) Ordinance, can the land grant be executed and the proposed reclamation proceed. In addition to this, HUD are responsible for applying for the Issue of Notice to MarinerslMarine Department Notice.
AXIS Environmental Consultants Ltd AXVJ5J3/J92-000 Page 2
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Figure 1.1 Site Location Environmental Job No 192000, July 1996, Final Report
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Figure 1.2 Proposed Area For Reclamation and Dock Job No 192000, Jllly 1996, Final Report
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PROJECT DESCRIPTION
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2.0
2.1
PROJECT DESCRIPTION
PROJECT HISTORY
Hongkong United Dockyard (HUD) currently operate three floating docks. 'Whampoa', 'Taikoo' and 'United'. The floating dock 'United' (Figure 2.1) was built in Singapore in 1994 and towed to Hong Kong at the beginning of 1995 to replace HUD's floating dock 'Tsing Yi' which had reached the end of her useful life. Following an EIA in March 1995, United was moored at Yam 0 Wan, an area identified by the Marine department as being suitable for such operations. The dock has been operational for almost a year and has been subject to an ongoing Environmental Monitoring and Audit programme.
The objective of the proposed project is to provide an extension to HUD's land based facility in Tsing Yi to allow the dockside mooring of the United. The project can be separated into two distinct phases, the construction phase which involves the dredging, reclamation and relocation activities in Tsing Yi and the operational phase. The work involved in the construction phase is detailed below followed by a description of the emissions and the major activities on the dock. The impacts have then been addressed in subsequent sections for these two project phases.
2.2 PHASE 1 - RECLAMATION AND SITE PREPARATION
2.2.1 Introductiou
The construction period is anticipated to cover an I I month period commencing after the reclamation has been gazetted. The proposed area for reclamation lies adjacent to the HUD's existing land based facility where the floating dock Whampoa is moored. The coast line in the area of reclamation is rocky shore and is shown in the photograph in Figure 2.2. The water currents in the main channel adjacent to site are known to be strong with a maximum speed of over 1.2m/s, whereas in the bay currents speeds are very low. A submarine cable belonging to China Light and Power (CLP) passes through the proposed reclamation site and is currently exposed on the shore. This cable will be diverted or relocated from its present location as direct reclamation over it would create a maintenance problem. Figure 2.3 shows an extract from CLP drawing No IO-NE-3B which indicates the proposed relocation of the cable.
An outfall is located at the site and discharges storm water onto the beach where the invert level of the culvert is O.l5mPD. It is currently envisaged that the outfall will be extended to discharge through the new western seawall. This process should take approximately 2 months to complete.
The reclamation and mooring arrangements for the dock are shown in Figure 2.4. The construction of the reclamation and the anchor pockets are outlined below. The anticipated marine construction working area for the civil works is outside of the Ma Wan Fairway. Works which are relatively close to the Fairway are mainly excavation and filling of isolated anchor pockets and would take place over a limited period thus minimising disruption to marine traffic. The entire project is due to be completed within 10 months of the commencement of construction activities.
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Hongkong United Dockyards Ltd - Extension to TITL 108RP Proposed reclamation and relocation of United Floating Dock. Tsing Yi Environmental Impact Assessment - Final Report
2.2.2 Dredging
A geophysical survey has been undertaken which has indicated that there is very little sediment in the proposed reclamation area. Dredging will not be required in this area except, possibly, for a small area where the seawall will be constructed. The proposed dock location within the bay has accumulations of sediment up to 8m thick and based on the preliminary site investigation, it is anticipated that approximately 80,000 -140,000 ml of marine mud will have to be dredged for the preparation of anchor pockets for the dock and to provide an adequate working depth for the dock. The actual volume of dredged material is dependent upon geotechnical studies which will determine the slope required on the anchor pockets. The proposed excavation area is indicated in Figure 2.4.
The anchor pockets will be excavated to approximately 6.7m below the existing sea bed and some rock removal will be required to provide a working depth of -18.50m PO for the dock itself. Based on preliminary site surveys, it has been calculated that in addition to mud removal, 20,000 ml of rock will be removed through blasting. In addition to this, approximately 30,000ml of Completely Degraded Granite (COG) and alluvium will have to be removed.
Dredging work for the dock and anchor pockets will be undertaken using a metal grab. For the dredging of marine mud a closed grab will be used to minimise loss of sediments into the marine environment and a sealed metal grab will be used for contaminated sediments. Materials which cannot be dredged by metal grabs will be broken up by blasting and then excavated by grab. The dredging process is expected to involve 2 grab dredgers operating over a 4 month period.
2.2.4 Blasting
Typically blasting involves the use of crawler drill rigs travelling on a cantilever frame welded to a barge using a 4 point mooring system to drill the holes. Once drilled, the holes are lined with PVC to ensure that they remain open and free from overburden prior to charging. Divers will ensure that casings are correctly installed and are roped together for later location and ease of charging. Each hole is then charged with the correct amount of explosive and then bunch connected using a detonating cord and fired using an electric detonator (Maunsells pers com., 1996).
2.2.5 Reclamation/Seawall
The block work seawalls (Figure 2.5) will be created using rockfill and concrete blockworks will be placed on top of the foundations to form the seawall. Fill material will then be imported to the site and deposited in areas bounded by the proposed block work seawalls. Rock and sand removed from the anchor pockets and dock area will be used as fill and additional fill may be imported from the Peoples Republic of China (PRC) unless an alternative source becomes available. If sand is imported from the PRC then Works Branch Technical Circular No 10/95 will be followed (Appendix I). Filling would either be by rapid discharge or using a grab and sufficient material will be used to create a finished level of 5.3mPD. The Marine Department will be consulted prior to finalising the filling method.
2.2.6 Anchor Pockets
Following dredging work, the anchors, 20-22 of which will be transferred from their current
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2.2.7
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wide, 4.8m long, 3.5 m high at the back and 2m at the front. The pockets will be filled with rockfill or some form of granular material to the required level by either rapid discharge or through using a grab. It is anticipated that the anchor pockets will be prepared and finished over a 3-4 month period. The design will consider the need to remove the anchors when the dock is decommissioned
Land Use
The proposed shipyard extension will utilise the land adjacent to HUD's existing facility, currently used by a container storage company. The reclamation would incorporate a small area of additional land which is currently zoned as green belt. Due to the need to gain access from land onto the dock after relocation, it will be necessary to relocate the current container storage area onto the proposed reclamation site. There will be no increase in the current container storage area. This issue is discussed further in Section 3.
Relocation of the Floating Dock
The timing of the project is critical due to the need to move the dock outside of the typhoon season. The current proposal is to move the anchors in late February 1997 and to have the site ready for the dock so that it can be moved from Yam 0 Wan to Tsing Yi before the start of the 1997 typhoon season.
Prior to relocating the dock from Yam 0 Wan to Tsing Yi, 20-22 of the anchor blocks will be recovered. This is achieved by disconnecting the mooring chains from the chain stoppers and lifting the blocks by means of a floating crane. It is not anticipated that dredging is required as the blocks have only been in place for approximately a year. The anchor blocks will be laid in the new positions prior to moving the dock.
The release of the remaining mooring chains will take place on the day that the dock is to be towed to Tsing Yi. The dock would be escorted by 5 tugs and it would take approximately 2-3 hours to complete the move to Tsing Yi. A suitable date and tidal window would be selected and agreement sought from Marine Department in advance. The entire process, including reconnecting the mooring chains, should take 10-12 hours. Once the dock is in position, the remaining blocks and chains will be recovered and laid at Tsing Yi.
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Hongkong United Dockyards Ltd· Extension to TYTL I08RP Proposed reclamation and relocation of United Floating Dock. Tsing Yi Environmental Impact Assessment· Final Report .
2.3 PHASE 2- DOCK OPERATION
2.3.1 Dock Description
The United has a 40,000 ton lifting capacity and was built to comply with the Rules and Regulations of the Lloyd's Register of Shipping. All materials, equipment and machinery used on the dock are of approved type and standard. United is HUD's largest floating dock and its physical dimensions are given in Figure 2.1. The dock's mooring consists of 30 sets of Lloyd's approved U3 stud link cables and concrete anchors which are designed to withstand typhoons.
The dock is serviced directly from the Tsing Yi shipyard. All workers, supplies and services are brought to the dock by work boat and work barge on a daily basis. The journey from Tsing Yi to Yam 0 Wan is approximately 6 km and takes just over 30 minutes. Approximately 100 workers are on the dock at anyone time depending upon the nature of the work to be carried out on the ship in dock. In addition to the workers, approximately 6-7 ships crew are likely to be present. The normal working hours on the dock are 8.30 am to 6.00 pm, six days a week. Overtime work may take place in the evening or on Sundays as and when necessary.
The dock is powered by three diesel generators (one on standby) with an additional emergency generator which is arranged to start automatically to provide power to essential services in the event ofloss of power supply.
The dock has a comprehensive fire fighting system which consists of a fixed carbon dioxide system with alarms, portable extinguishers, fire alarms, fire pumps, hydrants and hoses.
2.3.2 Dock Operations and emissions
Introduction
Dock operations and impacts were discussed in detail in the first EIA prepared for the mooring and operation of United at Yam 0 Wan (Axis, 1994). For the purpose of this EIA, a summary of activities which are of environmental concern is provided below and key activities are described.
The main activities carried out on the United dock are:
• Hull repairs;
• Mechanical overhauls and repairs;
• Electrical overhauls and repairs;
• Hull cleaning and painting; and
• Regulatory surveys and inspections.
All of these activities involve the use of equipment and processes which have the potential to generate pollutants. Procedures have been developed and implemented on the United to ensure that the activities and processes are controlled such that any emissions aim to meet acceptable criteria and associated chemicals and wastes are appropriately handled, stored and disposed of.
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Key Activities and Discharges
Of the activities undertaken on the dock, hull maintenance which involves washing, grit blasting and painting are areas where impacts on the environment can be most significant. Key activities known to have the potential to impact on the environment through discharges to air and water are described below.
Hull Maintenance
High Pressure Water Washing
The first operation carried out on the majority of ships moved into the floating dock is high pressure water washing, which is used to clean the hull of the ship for regulatory inspection and recoating. Water washing involves the application of water under high pressure (about 2000 psi) through a small nozzle at the end of a wand. The pressure is sufficient to remove any marine growth, loose or flaking paint and tends to simultaneously remove the surface layer (up to about one micron thickness) of anti-fouling. This operation takes about 2 days per ship and typically requires 200 to 400 tonnes of water per ship at a rate of about 40 litres per square metre. Fresh water is normally used in this operation unless the ship's owner advises that seawater is acceptable. In the event that seawater is used, it is followed with a fresh water rinse to remove remaining salt particles.
The design of the ship is such that during the washdown period water drains through the drainage port holes and the ends of the dock. Following the recommendations of the EIA for the operation of the dock in Yam 0 Wan, sand bags are placed along the side of the dock to ensure discharge is via the drainage port and not over the edge of the dock. This reduces the rate of discharge of the washwater into the marine environment thus allowing particulate matter to settle on the dock floor. This also reduces the amount of seawater flooding onto the dock, further encouraging particulate matter to settle. Measures are also being investigated on the dock to filter the washwater within the drainage port itself. The effectiveness of such measures is not known due to difficulties experienced taking samples from underneath the filters. Cloths discarded after a wash down period do not contain large amounts of solids which would indicate that they may not be trapping much paint. Much of the paint remains on the dock floor but process waters sampled from the drainage port above the filter do contain high levels of TBTs and observations in the laboratory would indicate that the TBT in the samples is coming from paint as the samples have changed colour during analysis due to the presence of paint. Apparently small amounts of paint can therefore have a significant influence on TBT contamination.
As a significant proportion of the solid material settles on the deck of the dock a key feature of good housekeeping in terms of minimising environmental impact is ensuring that solid waste is effectively removed prior to submergence. Material is collected using manual implements (brooms and shovels) and machines (small carts and bobcat loaders). The solid wastes are placed into skips until they are taken to HOD's waste storage facility at the main shipyard. The skip contents are then collected by licensed waste disposal contractors for disposal to landfill. The dock master is responsible for checking the cleanliness of the dock floor. Despite every effort to clear the dock floor of material prior to submergence it is inevitable that some material is left behind which may then be lost to the marine environment once the dock is lowered into the sea.
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Hongkong United Dockyards Ltd - Extension to ITTL I08RP Proposed reclamation and relocaOon o/United Floating Dock, Tsing Yi Environmentallmpacl Assessment - Final Report
Dry Grit Blasting
Dry grit blasting is an abrasive process used to remove primers, paints and anti-fouling applications to prepare the hull for new protective coatings. It involves the application of copper slag pellets propelled by compressed air of about 100 psi issued out of a ceramic nozzle.
Approximately 50% of dry-docked vessels are subjected to dry grit blasting, a total of about 25 ships per year. Approximately 20 tonnes of copper slag pellets are used per 1000 square metres of ship hull, equivalent to the average surface area per ship to be blasted in a full operation, which takes about 2 days. However, grit blasting of entire hulls is unusual but more often spot blasting of rusty areas and areas with defective paint coatings. Any areas subjected to grit blasting are also cleaned by fresh water washing prior to application of primers and antifoulants.
Being a heavy material, the copper slag grits fall rapidly to the deck of the dock. The operators are trained to direct the blasting guns in a downward direction to minimise the air transport of the grits.
Good housekeeping measures are employed on the dock to ensure that copper slag is cleared from the dock floor. Again, a combination of manual implements (brooms and shovels) and machines are used to collect all grits from the deck at the end of the operation. Collected grits are placed in steel skips which are transported to the Tsing Yi shipyard facility for subsequent collection by licensed waste contractors. The grits are held in a designated storage area until collected and disposed of to landfill by the contractors. As before, the dock master IS
responsible for checking that the dock floor is completely clean prior to dock submergence.
Painting and Degreasing
Primers, antifoulants and paints are applied manually by brush and roller or for larger areas, by hand held spray guns. Finishes are provided by the ship's owner and as the costs of these materials is substantial, supervisors ensure that paints are applied correctly and sparingly.
Lacquer thinners are used for thinning paints and antifoulants, and for cleaning up paint application equipment.
Waste paints and other wastes are currently collected in 20 litre drums for disposal to HUD's onshore facility. The production, handling and disposal of materials such as waste paints and oils are governed by the Waste Disposal Ordinance (WOO). In accordance with the conditions of HUD's existing Licence to Collect and Transport Chemical Waste, the wastes are stored in HUD's Designated Temporary Storage Area until the drums are collected by a Licensed Waste Collector. HUD is a licensed producer of wastes listed in Schedule 1 of the Waste Disposal (Chemical Waste) (General) Regulation.
Sewage and Grey Water
Sewage and grey water is directed to the on-board package sewage treatment plant, a Super Trident Model STIO unit. This unit employs the extended aeration process to produce a design effluent quality better than:
• BODs 40 mg/L
• Suspended Solids 40 mgfL
• Total Coliforms (MPN) 20011 OOmL
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The unit is designed to treat up to 17,500 litres per day and is an approved U.S. Coast Guard Marine Sanitation Device (MSD). The sewage treatment works includes on-line chlorination. The discharge' from the plant is currently licensed under the Water Pollution Control Ordinance (WPCO) and the licence conditions are set out in Appendix 2 of this report.
Generator Exhausts
Atmospheric emissions from the generators comprise normal exhaust emissions from diesel fueled equipment. The generators are on the upper deck of the dock and exhaust gases are discharged through vertical stacks to ensure rapid dilution and dispersion. Once the dock is moored at Tsing Yi it will be classed as a land based facility and the generators will require approval under the Air Pollution Control Ordinance which is discussed further in section 5 below. Plans are underway to apply for shore electrical power from China Light and Power Co, as is the case for the Whampoa.
Wastes
Wastes derived from the operations on the dock and include excess paint and antifoulants as well as thinners, kerosene and detergents which are collected in 20 and 200 litre drums. The production of hazardous wastes is controlled by the Waste Disposal Ordinance (WDO) and is covered by HUD's licence to be a registered chemical waste producer. The drums are temporarily stored in a designated storage area on the working platform until they are transferred to the main shipyard at Tsing Yi, There are no other chemicals or hazardous substances used in significant quantities.
The use of antifoulants containing TBT is controlled by the Agriculture and Fisheries Department (AFD) under the Pesticides Ordinance (Chapter 133). Users are required to hold a permit for each type of TBT antifoulant used. HUD is registered with the AFD as a user of TBT antifoulant paints which are supplied by their clients and are subject to periodic checks by AFD officials. The company hold current permits for a range of different TBT antifoulants and complete records are maintained by HUD in relation to the use of these materials.
Leakages and Spillages
Procedures are implemented on the dock to ensure that any spillages or leakages of paints, thinners, kerosene, fuel, oil and any liquid wastes, will be cleaned up immediately. As well as being an environmental hazard, such spillages are a safety hazard and the company's occupational health and safety policies require immediate action to be taken, particularly with respect to lubricants and flammable solvents. Sawdust used to absorb spills is stored in a number of bins on the dock. Used material is collected in solid waste bins for transport ashore to Tsing Yi and collection and disposal by licensed contractors.
With respect to prevention of oil pollution, HUD have an Operational procedure, Oil Pollution Controls (ref HUD-MAR-006) which ensures all staff are aware of company procedures to prevent and deal with oil spills. The document sets out the responsibilities of staff and necessary actions so that staff acquire a sense of responsibility in the matter of good housekeeping and safe and proper handling of all liquid chemical products. A key feature of the procedure is prevention and readiness. The Ship Repair Superintendent is in charge of vessels scheduled to undergo repairs at the yard and he is responsible for ascertaining from the ship Owner or Master if there is a need for the removal or transfer of oils to facilitate the planned repair works and if so, the owner is urged to deal with this problem prior to arrival at the floating dock. Also, to lessen the risk of oil pollution, the loading of fuel oil bunkers to vessels undergoing repairs is not permitted under any circumstances. Best practices are
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Hongkong United Dockyards Ltd - Extension to TYTL I08RP Proposed reclamation and relocation of United Floating Dock. Tsing Yi Environmental Impact Assessmenl- Final Report
employed for pumping or transporting oil and chemicals from ships for storage or disposal and collected oils are stored or transported in dedicated holding tanks.
In the event of an oil spill there are two oil contingency plans brought into action. Firstly HUD's in-house operating procedure on Oil Pollution Controls (ref HUD-MAR-006) contains an oil spill contingency plan. These procedures set out the responsibilities of personnel in the event of an oil spill, reporting procedures, risk assessment and emergency responses. In addition to these operational procedures there are 12 x 25 litres of Oil Spill Dispersant stored in drums on United with additional dispersant stored on the Taikoo and in the main yard, and 6 x 50ft lengths and 2 x 30ft lengths of oil boom stowed on the dock which complies with the Marine Department's Hong Kong Oil Pollution Contingency Plan (HKOPCP) requirements. When a high risk situation (serious oil spill has/is likely to occur and source of spilling oil cannot be stopped) is identified then the Marine Department Port Services Division is immediately notified whereupon assistance can be obtained.
The Marine Department's HKOPCP sets out procedures for the Government's response to oil pollution in Hong Kong's waters and provides a guide to the Marine Department's response -chain of command; information flow and available equipment. The HKOPCP also contains a comprehensive list of emergency contact numbers. The primary aim during an oil spill is to protect specific areas deemed to be of importance (Sites of Special Scientific Interest, Fish Culture Zones, gazetted beaches etc.,) and to limit the extent of pollution damage. The secondary aim is to clean up stranded oil. The final disposal of any waste oil is controlled under the Waste Disposal (Chemical Waste) (General) Regulation.
All spills, regardless of size, are documented under HUD's Operating Procedure and reported to Marine Department. Following an oil pollution event appropriate clean up measures are used and all equipment used in the oil spill is cleaned and once again made ready for use. Major oil spills are extremely unusual and minor spills will be minimised following relocation as there will no longer be the need to transport hazardous material from the main shipyard to Yam 0 thus minimising the risk of minor spillages at sea.
The Operating Procedure will be revised for the relocated dock to ensure that all areas of importance are identified within the procedure as priority areas for protection. These will include the Ma Wan Fish Culture Zone and the gazetted beaches in Ma Wan and along the Tseun Wan - Sham Tseng coastline.
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BASELINE CONDITIONS
SECTION 3
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3 BASELINE CONDITIONS
3.1 WATER QUALITY ------ --
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3.1.1 Relevant Legislation
The project site lies within the Western Buffer Water Control Zone (WCZ) which was designated in [993. Water quality objectives for this area are summarised in Appendix 3. The water quality objective for toxicants is that they should not be present at levels causing a significant effect. For suspended solids, the objective is that waste discharged into the WCZ should not raise the natural ambient level above 30% nor cause the accumulation of suspended solids which may adversely affect aquatic communities.
The discharges from the dock (washwater and sewage effluent) are currently licensed under the Water Pollution Control Ordinance (WPCO) (Cap 358). The licence covers the period September [995 to September [997 when it will be subject to review. Over this two year period an Environmenta[ Monitoring and Audit Programme, identified by the original EIA (Axis, 1995) is being undertaken. The findings of the EM&A programme will provide a basis for the next discharge licence. The relocation of the dock will result in the effluent being discharged into the Western Buffer Water Control Zone rather than the North West Water Control Zone. The discharge requirements will have to be revised as the discharge will be to inshore waters as opposed to marine waters as it is now.
With regard to specific legislation for Tributyl tins, there is currently very little which can be done to control the release of TBT to the marine environment. Internationa[ practice includes the regulation of paint composition and prohibition of their use on small boats, which tend to congregate in enclosed waters such as marinas. Some countries of the world, such as Germany and Switzerland, have prohibited the use of any organotin compounds in antifouling paints.
In the UK and France, TBTs were regulated in the aftermath of the events which resulted in serious impacts on marine life and detailed in Appendix 4. In 1982, as a result of the findings at Arachon Bay, the French Government banned the use of TBT-containing paints on all pleasure craft less than 25m in length. This measure has since been widely adopted and also applies in Hong Kong.
In the UK, the average TBT concentration found by MAFF to cause the disruption of growth in oysters, was used to set target limits for marine water quality. A safety factor of 10, which takes into account the extrapolation of these acute data to the chronic situation, reduces the value to 20 ng/1. This concentration was adopted by the UK as a target value for marine waters in [985 with an improved target of 2 ng/[ for 1989 (Goldberg, [986); this level has since been adopted by Canada and Australia (NSW EPA, 1990).
TBT copolymer paints with more than 7.5% TBT, and other paints with copper or other antifouling agents with more than 2.5% TBT have been banned since [986 in the UK on all vessels under 25m (which has effectively prohibited the use of free-association paints). In May 1987 in the UK, under the Control of Pollution (Antifouling Paints and Treatments) Regulations 1987, the retail and supply for retail sale of antifouling paints containing a triorganotin compound was prohibited for ships smaller than 25m. Under the UK's Food and Environment Protection Act 1985, all surface treatments and antifouling paints applied to yachts and larger vessels are subject to the pesticide approval scheme. A similar situation has been introduced to Hong Kong whereby all users of TBTs are registered by the Agriculture and Fisheries Department (AFD) under the Pesticides Ordinance, Cap. [33.
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In Australia, particularly in New South Wales, six different pieces of legislation provide the framework for control needed to regulate the use of organotins. Most relevant to this study is the Clean Waters Act, 1970. This Act is designed to control water pollution and requires any person wishing to discharge waste to obtain a license. Through this legislation washdowns from slipways can be controlled as the discharge may contain organotins in the form of soluble paint. residues, paint chips and dust resulting from shipyard equipment and procedures. Complementary controls are, however, required to cover disposal and collection of wastes on slipways.
Chemical Control Orders (CCO), gazetted under the Environmentally Hazardous Chemicals Act, 1989 in New South Wales are currently being revised with respect to controlling TBT wastes. The likely concentrations which will define wastes that will be subject to the new CCOare:
• Solid Wastes containing over 0.004 mg/kg.
• Liquid wastes containing over a yet to be determined value, probably in the range of 2-50 ng/1.
However it is unlikely that this CCO can be applied for large ship cleaning since it would not be practical to collect such large volumes of water for treatment prior to discharge (up to 500 tonnes of water). The Hong Kong Water Pollution Control Ordinance (WPCO), Cap.358, is similar to this in that a licence is required to discharge into the Water Control Zones (WCZ) of Hong Kong. The WPCO does not currently set limits for TBTs in the effluents or receiving waters but it does prohibit the release of all toxic substances into the WCZ, which could effectively ban the release of TBTs. As this is not currently practical on floating docks, discharges into WCZ are closely monitored and every effort made to minimise the potential for contamination.
3.1.2 Sensitive Receivers
Sensitive Receivers (SRs) are defined as "beneficial uses, which, by virtue of the nature of the activities thereon or resources therein, are susceptible to the influence of residual or physical changes generated by polluting uses" (Environmental Guidelines for Planning in Hong Kong, HK Government, April 1991). Sensitive receivers to impacts on water quality are beaches, particularly gazetted beaches where bathers can be affected by a deterioration in water quality, fish culture zones and marine ecology.
There are no gazetted beaches on Tsing Yi but to the north of Tsing Yi on the mainland and within the Western Buffer Water Control Zone, there are 8 gazetted beaches as shown in Figure 3.1. Of these beaches only Tung Wan beach on Ma Wan met the bacteriological water quality objective for bathing beaches in 1994 and had a water quality rating 'fair'. The remaining beaches are all ranked as poor with the exception of Angler's Beach which was ranked 'very poor' in 1993 and 1994 and closed for swimming purposes in the 1994 bathing season. Since then a continuing deterioration in bathing water quality has been observed. However, based on 1994 beach attendance rates Lido beach was the 5th most visited beach during weekends and public holidays in Hong Kong. It is anticipated that construction projects around the beach including Ting Kau Bridge may have reduced the popularity of this beach in recent months. Other beaches in the Tsuen Wan area had lower than average attendance rates for Hong Kong gazetted beaches, possibly due to poor water quality and large scale construction work in the area.
AXIS Environmental COJ1.mitants Ltd . '-AXVI 513!1 92-000 .-~
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In tenus of other receivers sensitive to impacts on water quality, the closest fish culture zone to the project site is on the western coast ofMa Wan Island as indicated in Figure 3.1. There are no sensitive marine sites in the vicinity of the project in tenus of ecology.
3.1.3 Water Circulation
Hydraulic model studies of the impact of bridge piers and a breakwater on tidal flows in the rambler channel (HWR, 1993) contain data relevant to this study. As part of the plume studies for this project, velocity vectors for the dry season spring tide were modelled (Appendix 5). The tidal flow modelling indicates that there are strong water currents in west Tsing Yi which flow in a north-south direction in the main channel and increase in velocity in the Ma Wan Fairway. Immediately west of the proposed site the currents are in the range of 0.4-0.8 ms·1 and increase to over 1.2 ms·1 within 250m of the proposed reclamation. Despite this strong current, within the bar, where the proposed project site lies, water circulation is significantly slower «0.2 ms· ) due to the sheltered nature of the bay. Field observations and patterns of sedimentation found in the site investigation support these data as soft sediments had only accumulated within the bay close to Whampoa.
3.1.4 Existing Marine Water Quality
Marine water quality is routinely monitored by the Environmental Protection Department. In the Western Buffer Water Control Zone there was full compliance with the WQOs for depth averaged and bottom dissolved oxygen levels and annual mean inorganic nitrogen. In 1993 there was an indication that inorganic nitrogen levels were increasing. Suspended solids for stations in west Tsing Yi ranged from 5.0 - 41.8 mg/l at WM3 and 3.2 - 22.7 mg/l at WM4. (EPD, 1993).
In tenus of bacterial levels coastal waters are ofa poor quality. According to the EPD (1994) the poor water quality in the Tsuen Wan district is caused by squatter areas and some unsewered developments. The Government plan to resolve this through the provision of sewerage along the coastal strip between Tsing Lung Tau in the west and Ting Kau which will collect waste from currently unsewered areas. The sewage will be treated at Sham Tseng where it will then be discharged via submarine outfall, directly north of Ma Wan. Once these measures are in place bathing water quality is likely to improve significantly.
Metals and TBTs are not routinely monitored in the water column as they have a tendency to associate with particulate matter and settle out of the water column. Ongoing monitoring work as part of the post project EM&A requirements for United has indicated that there are detectable amounts of TBTs (0.3-280 ng Snll) in the water column around the dock. Given that the Whampoa discharges process waters into the marine environment, it is assumed that there will also be detectable amounts of TBTs present in the water column in the Tsing Yi area.
3.2 SEDIMENT QUALITY
3.2.1 Legislation
The disposal of marine sediments is controlled by the EPD and Fill Management Committee (FMC). Contamination of sediment has to be detenuined through site survey to an agreed methodology with EPD prior to the detenuination of disposal options. Classification of sediments is set out in EPD's Technical Circular No 1-1-92 (attached as Appendix 6). This
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circular determines contamination according to heavy metal content. No legislation or guidance currently exists for TBT contamination in sediments.
3.2.2 Baseline Conditions
As part of the site investigation, sediment in areas likely to be dredged have been sampled from vibrocores (Figure 3.2) and sent for analytical tests in order to determine the degree of surface contamination and the depth of contamination. Also an initial survey has been undertaken which involved anaylsis of grab samples taken from surface sediments around the proposed mooring site (Figure 3.2). The analytical procedure for TBTs is set out in Appendix 7 which indicates sampling procedures, methodology, level of detection and accuracy of tests. Metals were analysed by a HOKLAS accredited laboratory using ICP-MS, a high energy plasma technique for the simultaneous determination of numerous elements as their isotopes. For mercury the cold vapour/atomic absorption spectrophotometry method was used.
Results will be submitted to the relevant EPD department and the correct disposal option for the sediment will be determined based on the Technical Circular No 1-1-92 and in consultation with the FMC. Grab samples have already been taken and analysed for the seven standard heavy metals and TBTs to provide an indication of the extent of sediment contamination. The results received to date from the grab samples and vibrocores are presented in Tables 3.2 and 3.3 respectively. TBT analysis currently takes over three months to get results but most of the results have been received and have been incorporated into this final EIA report.
Data available at the time of writing indicates that the majority of sediment samples were class C on the surface due to the presence of copper and in one case zinc but beneath the surface all sediment was class A. Three of the five grab samples also contained TBT although there is no classification for sediment contamination according to TBT levels. All of the vibrocore samples were contaminated with TBT and a maximum of 8,840 ng TBT/g were found in the sediments.
The surface sediment from the site, once dredged, would therefore be treated as seriously contaminated material which requires isolation from the environment upon final disposal. The disposal route will be dictated by the Fill Management Committee (FMC) and a confined dumping area for contaminated dredged materials such as that available at East Sha Chau is likely to be required. Geotechnical studies are being undertaken to determine the exact volume of sediment to be dredged as this will depend on the slope required for the anchor pockets which in tum is dependent upon stabililj of the sediment. At most, the total volume of sediment to be dredged would be 140,000 m . If the surface metre of sediment is treated as class C, then this would mean that a maximum of 35,000m3 of sediment would require disposal to East Sha Chau.
Sediment quality in the proposed area was also analysed at the end of 1994 when the EPD undertook a review of TBT contamination in marinas and shipyards around Hong Kong. The average TBT concentration was higher in 1994 than that found in samples analysed so far for the current site survey. This is probably because in 1994 two floating docks were in operation at HUD's Tsing Yi facility. The results provide evidence that sediments in the area are already significantly contaminated with TBTs and this is a result of past and current dock activities.
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Table 3.1 Sediment Quality in Grab samples taken from proposed mooring site, Tsing Yi (February 1996)
Sample
Moisture Content (%)
Cadmium (mg/kg)
Chromium (mg/kg)
Copper (mg/kg)
Nickel (mg/kg)
Lead (mg/kg)
Zinc (mg/kg)
Mercury (mg/kg)
TBTs (ng TBT/g)
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63.2 54.9
0.14 0.16
44.2 36.0
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23.9 21.6
45.1 45.0
114 91.5
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Hongkong United Dockyards Ltd - Extension to TYTL J08RP Proposed reclamation and relocation ofUniled Floating Dock Environmental Impact Assessment - Final Report
Table 3.2 Results from Vibrocore survey
Parameter / Depth Moisture Cadmium Chromium Copper Nickel
Sample Content (%) (mg/kg) (mg/kg) (mg/kg) (mg/kg)
VCI 0-2m 49.5 0.14 31.3 143** 17.3
2-3m 32.1 0.06 19.9 11.5 14.6
3-4m 34.6 0.06 21.4 13.9 14.5 4-5m 28.4 0.06 12.2 5.2 8.1
5-6m 23.8 0.04 12.0 5.4 7.7
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3-4m 31.1 0.12 17.7 16.1 10.0
4-5m 34.3 0.08 16.0 6.9 10.4
5-6m 35.1 0.09 16.7 6.6 11.2
6-7m 34.9 0.09 15.3 6.6 10.5
7-8m 32.1 0.09 16.8 6.7 11.4
8-8.75m 25.1 0.08 13.3 5.8 6.6
VC3 0-1 34.4 0.09 22.1 31.5 13.3
1-2 39.2 0.10 18.2 6.0 8.3
2-3 35.2 0.09 12.3 6.7 6.6
3-4 36.1 0.09 15.3 6.7 11.1
4-5 30.5 0.09 11.4 5.1 8.7
5-6 30.1 0.06 13.1 5.8 8.8
6-7 25.0 0.05 7.1 3.5 4.6
VC4 0-lm 46.7 0.19 33.2 95.4** 19.0
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2-3m 41.2 0.10 22.8 9.7 14.7
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Lead Zinc Mercury TBT ng (mg/kg) (mg/kg) (mg/kg) TBT/g
33.0 152** 0.13 8840 18.4 48.0 <0.04 26.1 47.1 0.14 ,
18.8 31.4 0.04 20.6 31.8 <0.04
20.7 30.7 0.06 257.4 16.0 33.2 <0.04 16.8 31.4 <0.04 31.3 48.5 0.25 23.8 44.0 0.04 25.3 42.0 0.05 23.0 43.5 <0.04 22.5 43.2 <0.04 22.5 29.8 <0.04
24.0 59.0 <0.1 3120 14.9 30.7 <0.1 14.7 30.9 <0.1 18.9 38.8 <0.1 18.9 36.5 <0.1 19.3 38.0 <0.1 15.4 22.1 <0.1
46.3 125.0** 0.10 44.7 80.9 0.21 22.2 49.5 0.04
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Moisture Content (%)
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Cadmium Chromium (mg/kg) (mg/kg)
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9.S 10.S 29.6 4304 <0.04 1430 44.7 10.1 46.9 73.6 0.12
64.S 22.7 39.3 95.S 0.1
Page l7
Hongkong United Dockyards Ltd - Extension to TITL l08RP Proposed reclamation and relocation of United Floating Dock Environmental Impact Assessment - Final Report
Table 3.3 TBT concentrations at HUD shipyard and toxicity, 1994.
Station TBT Conc. (ng Toxicity Reference TBT/g) dry
weight
12 254.8 0.5569
13 . 231.4 0.3733
14 1411.8 0.4879
Control 75.4 0.4506
Source (CES, 1995)
3.3 ECOLOGY
3.3.1 Introduction
TBTs are known to be harmful to marine organisms and therefore it is necessary to consider impacts on ecology for the proposed project. Dredging and reclamation can also potentially affect marine organisms directly or through loss of habitat.
3.3.2 Legislation and Guidelines
The Hong Kong Government Regulations and Guidelines relevant to this study include:
• The Marine Fish Culture Ordinance Cap 353 under which it is an offence to pollute waters in designated Fish Culture Zones (FCZ).
• The Fisheries Protection Ordinance (Cap. 171) which is intended to promote the conservation of fish and other forms of aquatic life within the waters of Hong Kong, to regulate fishing practices and to prevent activities detrimental to the fishing industry.
Care should also be taken to prevent or minimise pollution from discharges which may be carried by tides, currents or natural water courses to FCZs. Nature Reserves and Special Sites of Scientific Interest (SSSIs) should also be protected from the effects of pollution and from the diversion of natural flows.
3.3.3 Existing Ecology
In terms of ecological importance and conservation status, there are no sites of conservation, marine, agricultural or scientific interest in close proximity to the site, and the site is approximately 3km from the Ma Wan fish culture zone (FCZ).
A land based site survey of this area has indicated that the shore is rocky and there is unlikely to be any intertidal ecology of interest present. Terrestrial ecology is minimal due to general absence of vegetation in the area despite the zoning of this area as green belt, and the proximity ofTsing Ma Bridge and Lantau Fixed Crossing construction projects.
Axis Environmental Consultants Ltd AXVI5131192-000 Page 18
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3.4
3.5
In tenns of marine ecology the site consists of two different areas, the main channel and the bay where the dock is to be located. Preliminary site investigations (geophysical surveys and dives to locate submarine cable) have found that the seabed in the main channel in this area is largely rocky with limited sediment accumulation due to the fast water currents.
In the bay area, which is sheltered to a certain extent by the Whampoa dock, soft sediment has accumulated to up to 8m in places. Several large shipyards operate along the northern coast of Tsing Yi and floating docks have operated in south west Tsing Yi for many years. The sediment is known to be toxic (CES, 1994) and contaminated with Tributyl Tins (TBTs) and metals to grade C contamination in places, whereas water is known to be contaminated by sewage. The area is therefore unlikely to support anything other than pollutant tolerant organisms and benthic ecology is expected to be of minimal interest.
TRAFFIC
The site lies at the end of Sai Tso Wan Road which has a number of container handling areas along its length often resulting in the road being very busy due to container traffic.
HUD's operations will be maintained at existing level as will the container handling area at HUD, therefore, there will be no additional road traffic generated. While the construction work is in progress, only minor construction traffic wi1l use the road for a period of 6-9 months for transporting ready mixed concrete for the seawall coping pavement and other minor work.
All of the fill material for the reclamation is expected to either come from the adjacent Lantau Fixed Crossing Site, the excavated material generated by this project or the Pearl River by barge. Since the reclamation is away from the Ma Wan Fairway this would have no significant disturbance on nearby marine traffic.
In view of the above facts, the Transport Department has agreed to waive the requirement for a full Traffic Impact Assessment of this project. Relevant correspondence regarding this agreement is attached in Appendix 8.
NOISE
Western Tsing Yi is predominately an industrial area and is separated from residential areas in the east by a large area zoned as green belt. Noise sensitive land uses are listed in the HKPSG and include residential areas, schools and hospitals. There are no such land uses in the vicinity of the project site. Although background noise levels have not been measured for this assessment they are known to be elevated by the major construction work that is currently taking place in the area, in particular the new Tsing Ma Bridge and other major infrastructure associated with the new airport. In the immediate vicinity, noise is dominated by the construction of the bridge and airport link road together with movements at the container storage yard and repair works at HUD's land based facility.
3.6 AIR QUALITY
3.6.1 Legislation
The Air Pollution Control Ordinance is the principal legislation for air quality management and provides for the control of air pollution from stationary sources and motor vehicles. Table 3.4 below sets out the Air Quality Objectives for Hong Kong.
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Note.
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Average concentration (llg/m3)
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3.6.2 Baseline Conditions
3.7
Tsing Yi is not routinely monitored by the EPD. The closest monitoring stations are in Tsuen Wan and Kwai Chung. Air quality there exceeds air quality objectives for total suspended particulates (TSP) in Kwai Chung and both TSP and respirable suspended particulates (RSP) in Tsuen Wan (EPD, 1995). It is anticipated that with the construction work going on in the vicinity of the project site and the industrial nature of surrounding areas, the existing air quality on Tsing Yi is probably relatively poor. As for noise, the HKPSG states land uses considered to be sensitive to impacts on air quality include residential areas, active recreation sites, schools etc. There are no such sensitive receivers in the vicinity of the project site.
PLANNING CONTEXT AND LAND USE
The proposed reclamation site lies adjacent to an area zoned as industrial (i.e. HUD's land based facility) and an area zoned as green belt (Figure 3.3). A small portion of the land zoned as green belt will, if the project proceeds, have to be redefined to industrial. This green belt area, which is only 3000m2
, lies directly adjacent to the abutment of Tsing Ma Bridge with Tsing Yi. The proposed area of green belt to be rezoned and its immediate surroundings offers little in terms of recreational opportunities and is of no ecological value given the proximity of containers, roads and industry. The southern and western sides of Tsing Yi have been identified as a major industrial area in Hong Kong and indeed the area is well segregated from residential areas by distance and a natural ridge. This area is the destination for relocated industrial developments from Hong KongIKowloon and other areas of Tsing Yi.
Given the above, the proposed rezoning of a small portion of green belt is not anticipated to have any environmental impacts and is in line with the general planning intentions for the area.
Axis Environmental Consultants Ltd AXVJ513/J92-ooo Page 20
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CONSTRUCTION IMPACT ASSESSMENT
SECTION 4
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4.0 PHASE 1 - CONSTRUCTION IMPACT ASSESSMENT
4.1 INTRODUCTION
The following sections address the key impacts identified during the scoping stage of the project which are likely to arise as a result of the construction activities. A major issue of concern in terms of environmental impact is effects of dredging and reclamation activities on water quality. Impacts on marine traffic are also considered here together with construction noise and air quality impacts.
4.2 POTENTIAL IMPACTS OF EXCAVATION
4.2.1 Dredging Impacts on the marine environment
Mechanical excavation and dredging will be undertaken using 2 closed grab dredgers which will be operating over a 4 month period. Dredging physically disturbs or removes the bottom substrate including habitat for benthos, deposits sediment on the surrounding substrate, suspends sediment in the water column, reduces light penetration, increases turbidity, reduces dissolved oxygen and increases nutrient levels in the water column. Given that there is not considered to be any organisms of conservation importance within the works area, the potential loss of benthic organisms entrained within the removed mud is not considered to be an issue of concern. The key consequence of dredging and excavation (both mechanical and that aided by explosives) will be the generation of suspended solid and turbidity and subsequent secondary impacts on marine life.
The actual impact of creating a sediment plume within the marine environment is dependent upon the rate of release and sediment quality. The impact was studied further using plume dispersion models. Modelling is described in Appendix 5 and output from the models is also attached in the Appendix. Scenario 2 provides an indication of the fate of the sediment plume caused during the dredging of anchor pockets and material released from explosions. Material would be dispersed rapidly and would have a lower impact during the ebb tide than the flood tide when sediment may be transported to coastal waters adjacent to gazetted beaches. Given that the majority of the dredging work is programmed to take place over a four month period during the dry season, impacts on bathing water will be relatively short term and only affect the end of the bathing season. It is considered most unlikely that many people will be bathing in these waters anyway given the poor bathing water quality described in Section 3.1. The better beach on Ma Wan is unlikely to be affected by the plume.
Dredging of surface sediments will result in a plume within which there is the potential for the release of contaminants, notably copper and TBTs both in the dissolved state and particulate form. Once in the water column, TBTs are more available to marine organisms, particularly molluscs, and are therefore toxic at lower concentrations (as low as 20ngll) than when they are bound to particles in the sediment. They do however have a significantly shorter half life (weeks as opposed to years) in the aqueous phase and are removed from the water column either through the process of sedimentation following adsorption of TBT onto particulate matter or through breakdown into dibutyl and monobutyl tins which are progressively less toxic due to the loss of alkyl groups reducing their biological activity (Dirkx et ai, 1992). Sedimentation rates indicated by the model can be used to calculate the worst case scenario. Given the highest values of TBT found in the grab samples taken from the sediment (858ng TBT/g) then a maximum loading of 25.7 Ilg TBT per square metre could result per tidal cycle. This loading would be restricted to a localised area close to the proposed site where sediment quality is already poor due to the nature of activities in west
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Hongkong United Dockyards Ltd - Extension to TYTL I08RP Proposed reclamation and relocation of United Floating Dock Environmental impact Assessment - Final Report
Tsing Yi. It is therefore considered that the dredging would not generate any significant impacts as a result of contaminant release.
Since most of the dredging will take place in the bay area where sediment has accumulated to up to 7m in depth, the peak concentrations of both suspended solids and contaminants will be localised but the plume will still extend north and, south of the area. The area where the plume will have greatest impact does not contain any sensitive receivers and is not thought to support any marine organisms of conservation value. Metals are generally present in forms unavailable to marine organisms within the sediment and generally remain so during dredging. Opportunistic species dwelling in these waters will quickly recolonise or have the ability to withstand the short term impacts caused by dredging.
4.2.2 Impact of explosives used in excavation on Marine Environment
The proposed use of explosives to aid excavation of grade 3 rock in the area has potential ecological effects. Underwater blasting work is required to provide an adequate working depth for the dock.
Underwater explosions can cause considerable physical disturbance to both water column and benthic habitats. Impacts are proportionately greater closer to the detonation sites, particularly for open water explosions. Fish populations for example can suffer massive mortality and injury (Carpenter & Maragos, 1989) upon detonation when the swim bladder of teleost fish, an air filled sac, explodes causing the spine of the fish to break. However, evidence suggests that projects involving operations with staggered detonation times or explosives with slower detonation speeds can cause significantly less impact (Carpenter & Maragos, 1989). In Hong Kong, all underwater blasting work requires the explosives to be put in drilled holes on the seabed to focus the blast and limit the amplitude of the pressure waves transmitted into the water column. Blasting for other projects in the area, including Ting Kau Bridge, have not resulted in reports of significant fish kills during the EM&A phases of the works.
4.2.3 Mitigation ofImpacts arising from excavation on marine environment
In order to mitigate potential impacts on water quality during the construction phase It IS proposed that closed grab dredgers are used to remove contaminated sediments in order to minimise loss of material to the marine environment. To reduce the extent of plume dispersal, dredging will not be carried out during fast flow events.
There are several measures that can be taken to minimise adverse impacts caused during dredging operations:
• minimise disturbance of the seabed during dredging;
• minimise loss of dredged material during lifting;
• use closed grabs designed and maintained to avoid spillage and seal tightly during lifting;
• prevent overflow of hopper/barge being used;
• do not wash out barge or hopper while dredging or loading;
• barge/sediment transport system should be fitted with tight fitting seals to prevent leakage of material;
• ensure bottom openings are closed properly when vessels are full/on their way to disposal site;
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• remove excess dredged material from the decks and exposed fittings of barges before vessel is moved;
• avoid splashing/spillage of dredged material to surrounding water;
Wherever possible, during the removal of contaminated sediment a silt curtain will be used, however due to strong currents in the area this is likely to be impractical whilst dredging all but the most enclosed areas of the bay.
For practical and environmental purposes it is intended that blasting will be kept to a minimum and prior to blasting, divers will be responsible for checking the underwater casings which will hold the explosives. It is proposed that divers should also check for the presence of any large shoals of fish/ marine mammals whilst undertaking these checks. In the event that a dolphin/ large shoal of fish is spotted in the area then blasting work will be suspended. It is therefore anticipated that the ecological impact will not be significant. Prior to the commencement of blasting, the Mariculturalists at Ma wan will be consulted and informed of the time and location of the blasting so that they can monitor the impact of the blast, even though impacts 011 the lish are not anticipated.
4.3 IMPACTS OF ReCLAMATION
4.3.1 Impact on Marine Environment
As described in section 2 the project involves the reclamation of a small area equivalent to just over 100m by 100m. During the process of placing the fill into the area to be reclaimed, there will be some loss of water and fill material potentially increasing turbidity and affecting water quality in terms of suspended solids and dissolved oxygen in the receiving water.
The sediment plume dispersion modelling indicates that the sediment released during reclamation would be unlikely to affect the Ma Wan Fish Culture Zone. There is the potential for material to be transported to waters adjacent to gazetted beaches between Sham Tseng and Ting Kau but such impacts would be short term.
4.3.2 Impact on Traffic
4.3.3
All works will be undertaken from the marine side so the potential impacts of construction traffic on current traffic flow on the roads are not considered to be an issue. It is also anticipated that the majority of fill and construction materials will be transported to the site by barge.
The anticipated marine construction working area for the civil works is outside of the Ma Wan Fairway. Works which are relatively close to the Fairway are the dredging and filling of isolated anchor pockets and would take place over a limited period thus minimising disruption to marine traffic. The entire project is due to be completed within 10 months of the commencement of construction activities. In order to prevent any disruption to marine traffic, approval from the Marine Department would be sought prior to commencement of work within the Ma Wan Fairway.
Impact on Noise and Air Quality
General construction work such as dredging and filling is not anticipated to lead to significant increases to current baseline noise levels in the area. Given that there have been no sensitive receivers identified in the vicinity of the area, short term increases in noise would not cause an impact of concern.
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Hongkong United Dockyards Ltd - Extension to TYTL I08RP Proposed reclamation and relocation of United Floating Dock Environmental Impact Assessment - Final Report
The potential for air quality impacts during the construction phase of the project is small. Construction traffic will largely be marine based thus minimising the need for construction materials to be transported to the site by road which could lead to dust and vehicular emission impacts on other areas of Tsing Yi.
The reclamation itself will be a potential source of dust. The reclamation however covers such a small area and because there are no sensitive receivers in the vicinity of the site, potential short term impacts are not considered to be significant. Despite this, all standard precautions should be taken to suppress dust during dry periods. These include the use of water sprays and bowsers to water the site during periods of dry weather.
4.3.4 Solid waste
Dredged marine mud will be disposed of by the contractor according to the requirements of the Fill Management Committee which will be determined in accordance with EPD Technical Circular TC-I-I-92. The majority of the dredged sediment will not be contaminated but surface sediment is largely class C due to the presence of high levels of copper. It is likely therefore that surface sediments will be disposed of at East Sha Chau contaminated mud pits.
Rock waste and CDG will also need to be disposed of. Wherever possible this material should be used as fill for the reclamation thus reducing the volumes of material to be disposed of and the amount of material which needs to be brought in from the PRC.
4.3.5 Mitigation oflmpacts caused during reclamation
It is anticipated that through constructing the rock work sea wall first, loss of fill material to the marine environment will be minimised. Should there be a release of material then the impact should be short term as the slow moving water in the bay will result in rapid sedimentation, or in the channel, the fast currents in the area will ensure that it is dispersed rapidly thus minimising any impacts. As the ecology of the area is not of any significant conservation value and there are no major fishing activities in the immediate vicinity of the works, such short term impacts are not considered to have any significant effects on marine life. It is recommended that monitoring throughout the construction phase is undertaken to ensure that any adverse impacts on marine water quality, especially near gazetted beaches are detected at an early stage and appropriate action can be taken by the contractor to control and reduce the impact.
Wherever possible excavated material from the anchor pockets should be used in the reclamation in an effort to minimise disposal requirements thus putting excavated material to a beneficial use and minimising the need to source material from the PRC.
4.4 IMPACT OF RELOCATION PHASE
4.4.1 Impact On Marine Environment
HUD intend to transfer the concrete blocks used to anchor the dock from Yam 0 Wan to Tsing Yi. The removal of anchor blocks will inevitably result in the disturbance of sediment in the area. This may result in short term localised impacts caused by the resuspension of particulates and contaminants into the water body. Given that the dock has only been in its current location for less than one year, there is unlikely to be a·significant depth of sediment over the blocks. Short term impacts are not expected to be any greater than the impact of a
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single washdown period on the dock should it continue to operate in the area. The anchor pockets at Yam 0 Wan will then be left to fill in naturally.
4.4.2 Traffic Impacts
The relocation of the dock may result in disruption to marine traffic as it is transported through a busy shipping area. The dock would be escorted by 5 tugs and it would take approximately 2-3 hours to complete the move to Tsing Yi. Permission to tow the United to Tsing Yi will be sought from the Marine Department in advance and a suitable date and tidal window would be selected through liaison with Marine Department. The entire process including reconnecting the mooring chains should take 10-12 hours.
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PHASE2-
OPERATIONAL PHASE IMPACTS
SECTIONS
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5.0
5.1
PHASE 2 - OPERATIONAL PHASE IMPACTS
INTRODUCTION
As described in section 3, the docks operations result in the release of washwaters to the marine environment, this discharge is the key process in terms of impact on the environment. In the dock's current location it has been found that process waters cannot be collected for treatment due to the design of the dock. Potential opportunities do exist for collection and treatment of process waters once the dock is moored adjacent to the shore and these are discussed under Impact Mitigation. Operational impacts have been considered below, focusing on the impact of wash waters on the marine environment and providing a comparison of the impacts currently occurring in Yam 0 Wan with the potential impacts of the operations should the dock be moved to Tsing Yi.
5.2 IMPACT OF PROCESS WATERS ON THE MARINE ENVIRONMENT
5.2.1 Suspended Solids
5.2.2
The suspended solids concentration of the waste water would depend on the quantity of marine growth on the vessel hull. The wash down process does not result in a rapid discharge to the marine environment, particularly now that good levels of house keeping on the dock ensure that sand bags and filters are used around the drainage ports. This enables a large proportion of the suspended solids to settle out. Monthly monitoring of waters discharged to the marine environment have indicated that suspended solid content (Table 5.1) is well within the standards set in the discharge licence. Suspended solids are therefore only of concern because they may be contaminated with TBTs and metals and this is discussed below.
Potential Impact of Trihntyl Tins (TBTs) >
As identified in the previous ErA (Axis, March 1995), TBT is of key concern due to its impact On marine life. Observed impacts of the docks operations at Yam 0 Wan provide useful information for impact assessment in Tsing Yi. Water samples have been taken at various points in time around the Taikoo and United as part of the ErA for the mooring of United at Yam 0 Wan and the subsequent EM&A work. These results are presented in Table 5.2 below. The sampling points are based on a crucifix pattern centred on the dock. Concentrations are dependent upon activities on the floating dock at any point in time and concentrations can be significantly affected by the presence of a single paint chip within the fraction of the sample analysed. Despite this the general trend appears to be a significant increase in TBT concentrations in ambient waters around the dock.
TBTs have been measured in process waters discharged from the dock and the results have indicated that the water (prior to any filtration) is heavily contaminated. Table 5.1 presents some of the results from samples taken to date.
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Table 5.1 Quality of process waters discharged from dock
Effluent BODs Oil and Total Chromium Grease Suspended
(mg/I) Solids (mg/I) (mg/I) (mg/I)
09/95 <10 <10 104 <0.01
10/95 90 11 10 0.04
11195
11195
11195
2711/96
5/2/96
27/2/96
+ indicates exceedance of standards set in Technical memorandum/Discharge Licence N.B Analytical results multiplied by 2.6 to convert value from ng Snil to ng TBT/I
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Copper Lead Zinc
(mg/I) (mg/l) (mg/l)
0.8 0.05 2*
7.0* 0.1 4.1 *
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TBT Suspended
(ngTBT /It Solids (mg/L)
16,120 20
8,400 -
83,200 -
range:46,800-962,000
range: 241,800-4,160,000
range: 44,200-598,000
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The values measured in the washwaters are not necessarily the concentrations of TBTs released to the marine environment given that HUD have implemented good housekeeping measures over the past year of operations, such as use of filters and sandbags over drainage ports. Despite these efforts, analysis of sediments has indicated that TBTs are accumulating and reaching significant levels around the dock (on average 6,725 ng TBT/g and a maximum of 41,600 ng TBT/g) (Table 5.3 and Figure 5,1), As found in the previous ErA (Axis, March 1995) when sediments were analysed around the Taikoo, the greatest concentrations are found along the main axis of the dock which is aligned in the same direction as tidal currents in the area. Higher concentrations are recorded along the eastern axis either due to the ebb flow having a stronger influence on sediment dispersion, as indicated by plume dispersion modelling, or due to the fact that this side of the dock is closer to other floating dock operations in the area,
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Table 5.2 Tributyltin* in waters around Floating Docks in Yam 0 Wan, North Lantau.
Sample Baseline Waters around Waters around Surface Waters Location TBT (ng United, November United, February around Taikoo, (refer to TBTn) 1995 (ng TBT /1) 1996 (ng TBTn) Jan 1995 (2 yrs
figure 5.2) around operation) (ng United, June TBT/I)
1995
Surface! Surface Bottom Surface Bottom Surface Bottom Bottom
3 728 (S) 10.4 <0.78 13520 8840 80.6 468 /3,900
8 54.6(S) 5.2 143 9100 338 145.6 62.4
12 <0.78 (B) 18.2 2.6 223.6 70.2/ 416 59.8 132,600
17 <0.78 (B) 5.2 2.6 572 1716 59.8 57.2
*n.b due to analytical method of AAS to detect elemental tin, / ng Sn = approx 2.6 ng TBT, (CES, /995) results have therefore been converted to TBTfor consistency throughout the report.
Table 5.3 TBTs in Sediments around United in Yam 0 Wan
Sediment Sample
Location
I 2 3 4 5 6 7 8 9 10 II 12 13 14 15 16 17 18
Axis Enviro'nmental Consultants Ltd AXV15131192·000
Tributyl Tin (ngTBT/g)
Baseline -June
364 98.8 1534 936 8060 468 1742 1352 364 416 728 520 806 1326 372 364 1144 312
Tributyl Tin Tributyl Tin (ngTBT/g) (ngTBT/g)
October 1995 February 1996
3380 4940 3640 2600 2\06 6760 5200 41600 3640 23920 624 26000
2184 468 3380 806 1430 244.4 2184 754 936 2080 624 520
3380 1820 1430 72.8 85.8 182 962 4940 364 2418 2860 858
Page 29
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Concentrations of TBTs in sediments around Tsing Yi were found to have a smaller range than those measured in sediments around Yam 0 Wan (Table 5.2). This is possibly a result of dispersion at Tsing Yi although concentrations can be significantly elevated in a sample due to the presence of a paint chips. The maximum concentration measured at Yam 0 Wan was equivalent to 40 mg TBT/kg and this was most likely to have been the result of the sample containing paint chips as the sediment shows a non uniform distribution of TBT. The analytical procedure is accurate (Appendix 7) and results are reproducable but duplicate samples were taken to demonstrate how much a sample from one location could vary. For example, a duplicate water sample from around United contained 70.2 ng TBT/I in the first sample and 132,600 ng TBTII in the duplicate sample, again indicating the influence of paint chips within a sample.
According to the literature (Tolosa et ai, 1992), of the TBT released to the water column, at equilibrium, there would be a higher concentration of TBT (87-95%) in the dissolved phase than TBT associated with particulate matter. However, the literature also states that anomolies are found around dockyards due to the fact that most of the released TBT is contained in paint chips thus preventing this equilibrium from being reached. As stated above, the non-uniform distribution of TBT found in sediments reflects the presence of paint chips containing TBT. Sediment also acts as a sink for the TBTs since the major pathway for removal of TBTs from the water column is through adsorption to particulate matter (especially the fine fraction) and subsequent sedimentation (de Mora et ai, 1995).
The impact of sediment containing TBTs on marine organisms has not been widely investigated and the determination of a safe level for TBT in marine sediment is therefore difficult. TBT in sediment does remain available to marine organisms in the benthos though the literature states that TBT contained within a paint chip is less available than that adsorbed onto fine material. TBT progressively disappears largely due to biotic or abiotic degradation. (Goldberg, 1988; WHO, 1989). With increasing sediment depth conditions become less aerobic and higher TBT:DBT ratios are found due to anaerobic degradation processes prevailing and half lives are increased to up to 2.5 years (Tolosa et ai, 1992; Harris et ai, 1991)
In an experiment to investigate the impact of paint chips containing TBTs in marine sediment it was found that surface sediment could decontaminate rapidly as a result of water movement and deposition of new sediment whereas subsurface levels remained reasonably stable during the experiment. The study which is described in the literature review in Appendix 4, looked at sediment samples containing 0.1, 1.0, 10 and 100 mg TBT/kg. Generally it was noted that there was a dose related effect on the burrowing activity of marine organisms and that filter feeders, which are surface dwelling organisms, were generally less affected due to the fact that they extract food from the overlying sea water rather than feeding on particles in the sediment. It was also noted that the effect of sediment containing O.lmg TBT/kg was lost after 3 months.
In the study commissioned by the EPD (CES, 1995), the hypothesis that levels of sediment toxicity are significantly elevated in the vicinity of shipyards was found to be true for certain shipyards in Tsing Yi. There was also found to be a significant correlation between levels of TBT contamination and toxicity of the sediments. The study also found that elevated levels of TBTs were found up to 100m from the shipyard due to dispersion of paint by the strong currents.
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TBT causes detrimental impacts on a range of non target marine organisms and is therefore a toxic marine pollutant. Impacts in sediment tend to be more localised than water impacts due to the nature of sedimentation of paint chips. Impacts will therefore be minimised to a certain degree due to the fact that there are not expected to be any marine organisms of interest in the immediate vicinity of the dock. However, the general increases in TBTs in the Hong Kong marine environment are an issue of concern. For example, investigations into the impact of TBTs on Hong Kong marine life are being undertaken by various bodies such as Swire Institute of Marine Science and University of Hong Kong. A study undertaken at University of Hong Kong has found that a significant proportion of the dog whelk, Thais ciavigera has suffered from the phenomenon of imposex, the induction of male sex characteristics on the female which ultimately leads to population imbalances and death to the affected organisms (Mak and Hawkins, 1996). This study suggested that TBT contamination in Hong Kong waters was some of the highest recorded in the world.
In the light of these impacts, TBT release from the dock has been quantified and dispersion investigated through modelling. This is discussed below.
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5.2.3 Quantification of Impact of TBTs [
TBT accumulation in sediments around floating dockyards in Hong Kong has the potential to C .... be harmful to marine life. It is also apparent that the key source of TBT from floating docks is from paint chips released during high pressure water blasting of the ship's hull. In order to assess the impact of paint chips, water quality model runs were undertaken to study the fate of particulate matter discharged from United, both in its current location and its proposed [ location at Tsing Yi, taking into consideration recent changes to bathymetry and the proposed . reclamation. Tidal Flow Modelling was undertaken to provide flow data for the sediment plume simulation and flow data were based on the W AHMO 250m grid flow model [ .. (Scenario 1) and 50m W AHMO grid model which had previously been set up to investigate the impact of Ting Kau Bridge. The sediment plume simulation was run for three tidal cycles each 24.5 hours in length for the dry season spring tide which represented the largest [. tidal excursion based on past modelling experience of the area. _
Two scenarios (Scenario 2 and 3) were modelled for Tsing Yi, the first considered the dispersion of a sediment plume if the waters were released from all sides of the dock (as is the current practice), the second looked at the dispersion of the plume should it be directed 100m into the bay on the western side of the dock. The release of process waters from the dock for the 3 scenarios is described in detail in Appendix 5. Modelling output is presented in the series of figures which are also attached in Appendix 5 and summarised in Figures 5.3-5.5.
In the Initial Assessment Report for the mooring of United in Yam 0 Wan (Axis, 1994) it was calculated that the area of dock likely to be painted with an antifoulant is 6000 sq m. Therefore the quantity of antifoulant likely to be removed from the dock during water blasting is 6kg. The most commercially available antifoulant applications contain less than 30% TBTM copolymer and the maximum concentration of TBTO, the biologically available Tributyl tin component is 1-5% by weight. The quantity of available TBT removed during each washdown period is 60-300 grams per ship. Each water blasting operation involves the use of up to 500 tonnes of water so the potential active TBT in the waste water discharge could be in the order of 0.1-0.6 mg/I (100-600 /lg/l).
The effectiveness of the housekeeping measures in terms of trapping paint in cloth filters placed over the drainage ports is difficult to quantify but should be considered so as not to over estimate the extent of the impact. The literature indicates that the housekeeping measures such as those now used on United can reduce TBT emissions by up to 40%
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(Haskoning, 1989, Study for the European Commission). Measurements of TBT in process water taken hourly over two wash down periods prior to discharge on United have averaged at 641 f!g/l with a maximum of 1.6 mg/L These values represent actual TBT lost to the marine environment and therefore do not include the amount of TBT in paint flakes trapped on the deck of the dock. To a certain extent, therefore, these concentrations include a consideration of housekeeping measures other than the mitigating effect of placing cloth filters over the drainage ports. These measured concentrations also indicate that the original calculation of TBT lost to the marine environment was slightly low. It is not known how much paint is trapped by the cloth filters on the drainage ports, but the average concentration of TBT in the washwater just before it enters the drainage ports has been used in the following calculations as a good indication of the TBT released to the marine environment in the washwater. The average is also in fairly close agreement with the range ofTBT originally calculated to be lost during a washdown period.
If 300 grams ofTBT are released over the washdown period then this would be equivalent to a loss of 0.0052 grams per second or 5.2 mg/s assuming that washdown occurs over two working days.
The model looked at a release of I kg of particulate material per second. A maximum of 4mg/1 of suspended matter was recorded in the water column under this scenario. Therefore if 5.2mg/s of TBT were released then 0.00002Img/1 would be the maximum TBT concentration in the water column in the form of particulates. This is equivalent to 0.021 f!g/l or 21ng/1. This concentration, while very low, is equivalent to the limit of TBT known to cause an impact on the growth or development of marine organisms. Therefore, one discharge alone would typically have the potential to affect a small area in close proximity to the dock with sufficient quantities of TBTs known to have chronic impacts on marine life. A proportion of this TBT will however be contained within the paint chips and will not be readily available to marine organisms and therefore the discharge alone, particularly when housekeeping measures are considered is, in practice, unlikely to be harmful to organisms within the water column.
Sedimentation rates are perhaps of greater concern since TBTs are able to persist in the environment for greater periods of time once they are removed from the water and may then accumulate to toxic levels. The model indicates that the maximum rate of sedimentation at the end of the tidal run was 30 g/sq m .. As stated above, TBT release rate over a washdown period is estimated to be in the order of 0.0052 g/sec. The maximum deposition rate, without considering any reduction caused by filtering etc., would therefore be O.l56mg TBT/m2
•
Also of concern with respect to TBT is cumulative impact. As TBT-containing paints are increasing in popularity again due to the inferior performance of alternatives, it is likely that a significant number ofTBT treated ships will be washed down over the period of time that TBTs persist in the sediment. The study quoted in section 5.2.2 above found that TBT present in concentrations as low as 0.1 mg TBT/g lost its affect on marine organisms within 3 months. During that 3 month period, however, a dock could washdown as many as 10 ships, all of which could be treated with TBT. Under this scenario over 1.5 mg TBT/ml could be deposited in the sediment where peak deposition occurs. As effect is dose related, over time TBTs will reach sediment concentrations thought to be harmful to marine life. Background concentrations of TBT from non point sources, such as the many ships using Hong Kong's waters, would also add to these concentrations, although this is difficult to quantifY.
The following compares the three scenarios studied in terms of cumulative impacts and sediment contamination. A fourth scenario and the preferred option, is discussed under mitigation of impacts, section 5.3.
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Scenario 1, the existing situation at Yam 0 Wan
Under Scenario 1, TBTs are dispersed to an area more widespread than originally expected and covers a far greater area than is currently monitored. In terms of particle deposition rates, the maximum rate of discharge (O.156mg TBT/m2) occurs over 0.38km2 and the total area of the plume is 15.66 km2
. Yam 0 Wan was identified by the marine department as an area suitable for the operation of floating docks but the site is closer than Tsing Yi to areas of marine ecological importance such as fishing areas and the dolphin sanctuary off Sha Chau which was due to be gazetted in April 1996. Although the plume studies have indicated that the discharges are unlikely to reach the dolphin sanctuary, the plume has the potential to affect waters used as feeding grounds for the dolphins and to a lesser extent, the Ma Wan FCZ. Figure 5.6 represents Chinese White Dolphin (Sousa Chinensis) sightings between June [990-August [991. It should be noted that these are records of sightings only and not the results of a scientific survey. Most sightings were in areas close to where people have been working (for example on the airport project around Chep Lap Kok) and do not therefore represent the total range of the Dolphin, they do however, provide evidence that the Dolphin frequents waters around North Lantau.
In terms of cumulative impacts, five floating docks currently operate within Yam 0 Wan in close proximity to one another. It can therefore be expected that the plumes from the docks (four of which are not thought to filter washwater prior to discharge) are dispersed over similar areas off the North Lantau coastline. Between the docks, maximum deposition rates of TBTs may coincide during anyone tidal cycle, depending upon activities on the docks. In the event that all were washing down TBT treated ships at one time then a maximum of 0.78 mg TBT/m2 would occur. As this would persist in the marine environment this could lead to significant amounts of TBT accumulating as is being found in the ongoing EM&A work where the latest data from samples taken in February indicate that over 6 mg TBT/kg is typically present and up to 400 mg TBT/kg has been found.
Scenario 2, Tsing Yi
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The modelled plume of particulates discharged in the wash waters reaches the coastal waters [ off 7 gazetted beaches. Concentrations of TBTs in the water, attributable to the United would however be negligible and in the order ofO.2ng/l here therefore thought to be harmless [' to marine life as it is one hundred times smaller than the concentration known to affect , marine life. Since the cumulative effect in the coastal waters of the discharge from the two docks at HUD's facility is below the level known to impact on marine life and the material is [ likely to settle out of the water column quickly, the impact on bathing water quality is >
considered to be negligible. Deposition rates within bathing water is very low, approximately 0.01 mg TBT/m2 based on the model output which indicates that deposition ['_ rates would be lowest here. Background concentrations along the Tsuen Wan coastline , appear to be varied. According to the EPD survey undertaken in [994 (CES, 1995), north of the western coast of Tsing Yi control levels were found to be 6[ ng Sn/g and further along at [' Gold Coast, TBT at the control station was as low as 1.9 ng Sn/g. It is not anticipated that _ the dock will increase TBT levels to harmful levels in the sediment close to gazetted beaches given that the TBT loading would be so low in the vicinity of the Tsuen Wan coast and [_', existing sources are not significantly affecting the sediment. ,
Peak deposition rates would occur close to the dock over an area of 0.0[km2• Cumulative
impacts would arise from discharges from the two docks, Whampoa and United, resulting in !-a potential peak deposition of 0.312 mg TBT/m2. This area is already contaminated with L TBT, between 46-8,840 ng TBT/g (Table 3.[ and 3.2) thus TBT could accumulate to significant quantities in the sediment around the docks. Due to historical contamination in [
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this area and the lack of marine species of interest, the ecological effect of the impact is unlikely to be significant as the benthos is not anticipated to contain organisms of concern.
Scenario 3 Tsing Yi,flow redirected 100m into embayment
Under Scenario 3 the deposition ofTBT occurs over a smaller area than under scenario 1 and 2. Since dispersion is reduced slightly by redirecting the flow, most of the particulates settle within an area closer to the dock than in Scenario 2. The area over which peak deposition occurs is greater than Scenario 2, i.e 0.22 km2
, although the total area of impact is slightly smaller; this is difficult to quantifY precisely as the plume extended beyond the boundaries of the model. TBT could accumulate to harmful levels along the west coast of Tsing Yi and the south coast of the western New Territories where relatively high particle deposition rates would occur.
Summary
Of the three modelled Scenarios, Scenario 2 is the preferable option in terms of reducing the area of peak deposition and would also enable HUD to increase the efficiency of operations on the dock allowing them to cease all operations in Yam 0 Wan, resulting in an overall reduction in TBT discharged into Hong Kong waters.
Although the modelling has indicated that the dock itself would not result in any significant contributions to TBT concentrations in the vicinity of sensitive receivers, there are many unknowns in terms of cumulative impacts. Washwaters do contain very significant levels of TBT as indicated by the analytical results, despite attempts to minimise TBT releases through good housekeeping measures, sediments around United are becoming elevated in TBT. The relocation will enable HUD to implement additional mitigation measures considered essential to ensure that impacts are minimised. If the dock is moved to Tsing Yi then Scenario 4 will be possible i.e. the collection and treatment of the washwaters from United and Whampoa docks which would greatly reduce TBT discharges to the marine environment. This is the preferred option and is described below in section 5.3.
5.2.4 Potential Impact of Metals
Since the waste water will inevitably contain a small quantity of antifoulant material present in paint chips, where TBT containing antifoulants have not been used, other antifoulants will be present. Additives to antifoulants include heavy metals, particularly copper and zinc. Metals discharged in washwaters from ships have also been monitored as part of the licence requirements for United and process waters have been found to contain elevated levels of both zinc and copper (Table 5.1). Sediments in Yam 0 Wan around both the United and the Taikoo also contain elevated levels (Class C) of copper and zinc as do sediments around the Whampoa floating dock in Tsing Yi. Copper may also enter the marine environment as it is used in grit blasting. Copper slag is an effective blasting material due to its inherent sharpness and it is also relatively cheap. The operation of the dock in Tsing Yi will therefore increase metal contamination in marine sediments. Unlike TBTs, metals are persistent in the environment and therefore release of these metals over a prolonged period could result in significant concentrations of heavy metals accumulating in the sediment.
The sediment plume modelling (Appendix 5) can be used to represent the fate of copper and zinc released from the dock as these metals usually precipitate out from the water phase or when present as a free ion or complexed ion they will usually be adsorbed to colloidal particles. Scenario 1 would indicate that metals are currently affecting a significant area of the North Lantau coastline. If the dock were to be relocated to Tsing Yi then sediments
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would receive smaller loadings of contaminants due to greater dispersion by the currents (Scenario 2). Directing the discharge into the bay where water currents are slower would allow high levels of metals to build up in the sediments close to the western shore of Tsing Yi and within the bay. Controlling the discharge by directing it into the bay does not appear to significantly limit the extent of the plume and it results in a larger area over which peak concentrations will occur and therefore has no environmental benefit.
5.2,5 Potential Impact of Sewage Effluent on Marine Environment
United was the first dock to be fitted with its own sewage treatment plant. The discharge from the plant is currently licensed under the WPCO and residual chlorine is measured on a weekly basis. Environmental Monitoring and Audit results have identified problem areas in the operation of the STP which have since been rectified and apart from on one occasion, there have been no exceedances of the effluent quality standards set out in the Technical Memorandum. Provided that the revised discharge licence for the dock includes this effluent stream, the discharge will continue to be monitored closely thus minimising the risk of water pollution. Sewage effluent is therefore not considered to be a discharge of concern.
5.3 MITIGATION OF IMPACTS ARISING FROM PROCESS WATERS
Due to the design of United it is recognised that the collection of process waters from the dock for treatment is not feasible in its current location due to the impracticalities of collecting and storing such large volumes of water on the dock. It is also clear from the modelling and monitoring experience at Yam 0 Wan that the dock's discharge will continue to impact upon marine sediment quality in its existing or proposed future location even with the continuation of good housekeeping measures.
Scenario 4 - Collection and Treatment of Wash waters from United
Relocation of the dock will enable HUD to collect the waters from the dock in a series of pipes attached to the dock's drainage ports and pump the water ashore where it can be collected and filtered, thus removing paint flakes containing antifoulants and solids such as copper slag. HUD are committed to implementing such a system and a preliminary design is given in Figure 5.7. A letter from HUD to the EPD stating their intention to implement such as system is attached as Appendix 9. Since HUD propose to implement this system on both the United and Whampoa it will be necessary to install a tank capable of containing 200-400 tonnes of washwater. The reclamation will therefore provide the land area necessary for installing such a treatment system and the system will be in place in time for the commencement of operations at TsingYi.
Paint flakes are thought to contain a significant proportion of the TBT lost in the washwater. Removal of the solids through filtering and/or sedimentation within a tank would therefore mean that TBT loading into the marine environment would be reduced. The actual percentage of TBT removed from such a treatment system is not yet known and therefore it is difficult to quantify the impact of TBT from the dock after treatment. The proposed EM&A programme will determine the effectiveness of the system. However, it should be noted that a study undertaken by Haskoning for the European Commission in 1989 states that,
"Settling tanks are the most important step for the reduction of the organotin content in the waste water stream (removal ratio of90-98.5%}."
It is therefore considered that the system will be effective in removing a significant proportion of the contaminants carried in the washwaters. Dissolved TBT will also be present in the
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washwater which may have been partly responsible for contamination of sediments around United in Yam 0 Wan as tbis would not have been removed from the washwater by the filters. The literature (de Mora, Stewart and Phillips, 1995) states that TBT is extremely surface active and rapidly adsorbs onto particulate material. It is possible that witbin the sediment tank a proportion of the dissolved TBT will adsorb onto particulate material and can then be removed through filtering. It is anticipated that with good housekeeping measures and tbe proposed treatment system up to 70% of the TBT that could be released into the marine environment will be captured.
After filtration the effluent would be discharged into the part of the bay where water circulation is limited, thus restricting, to a certain degree, the dispersal of any remaining contaminants. Since dissolved TBT is, from a toxicological point of view, the most significant form of TBT it is important that contamination is limited to an area known to be ecologically poor. Once in the water column tbe soluble TBT released from the treatment tank will be removed quickly through photochemical decomposition,' microbially induced debutylation and adsorption onto particulates where it will settle into sediments around Tsing Yi (de Mora et aI, 1995). Solid waste in the collection system would be disposed of in the correct manner with other waste collected from the dock. HUD propose to undertake tests to determine the effectiveness and suitability of this system and once tbey have devised an effective system, they will extend the system to collect washwaters from tbe Whampoa dock., also at Tsing Yi.
In order to ensure that a minimum of TBT and otber contaminants are released into the marine environment, HUD should continue to implement the good housekeeping procedures set out in their Operations Manual and their discharge licence (Appendix 2). In particular, it has been found that collection of waste from the dock floor and thorough inspections of the dock prior to washdown or submergence is a way of minimising tbe release of paint, antifoulant and copper slag to the marine environment. This will be important even with the introduction of a collection system as only tbe paint lost through tbe drainage ports will be collected through tbe pipes and subsequently filtered out oftbe discharge. It may be possible that the existing system of ensuring tbe deck of the dock is as clean as possible could be improved and this should be investigated in the EM&A stage. Use of sandbags along the sides and ends of the dock should also continue as this helps to limit the direct contamination of sea water with material on tbe dock floor. Such methods are used in Australia to prevent loss of paint flakes to the marine environment. Good housekeeping measures such as the sand bags, filters etc. would, however, be more effective if applied to the dock during the washdown and repair of all ships rather tban just TBT treated ships, as this helps to establish a routine for the workers which will always be followed.
Under Scenario 4 therefore there are many benefits which can be summarised as follows:
• Installation of collection and treatment system thereby reducing TBT, copper and zinc release from the United Dock and reducing environmental impact;
• Transfer of dockyard activities from Yam 0 Wan to Tsing Yi, a less sensitive area in terms of ecology;
• Improved safety on the dock in terms of emergency services and minimising distances over which chemicals and waste needs to be transported;
• Improved efficiency of dockyard activities through mooring dock adjacent to main shipyard allowing decommissioning of Taikoo in Yam 0 Wan and therefore reducing overall TBT input into Hong Kong Waters;
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5.4
• Extension of proposed collection system to include washwater from Whampoa dock so that all of HUD's docks will use best practical means for minimising environmental impact.
OTHER IMPACTS
5.4.1 Chemicals
Chemicals are stored in the main shipyard facility at Tsing Yi. The relocation of United will therefore not result in additional chemicals being stored in this facility. Chemicals are currently taken to United via the company work boat hence there is the potential for accidents to occur including leaks and spillages from the work boat which is used to transport all chemicals and waste from the dock to the main facility. The relocation of the dock to the shore will eliminate the need for the work boat thus eliminating this risk. Also, accidents on board United can be dealt with more quickly and effectively should the dock be brought to shore, again reducing the possibility of an adverse impact on the marine environment. Major oil spills are likely to be more easy to contain with booms etc once the dock is brought to shore particularly as more equipment will be readily available.
5.4.2 Impact of land based operations on Water Quality
The proposed project will result in the relocation of the container storage yard to the reclaimed area. The land currently occupied by the containers will be utilised for general repair work, similar to that undertaken at HUD's land based facility. These activities currently do not have a significant impact on water quality and this is expected to be the case in the future. The reclamation will be used for storage only and it therefore anticipated that there will be no impact on water quality. As a precaution, it is recommended that the drainage system on the reclamation has provisions for petrol interceptors to prevent the release of grease and oil in surface run off from the site due to the number of heavy goods vehicles using the site.
5.4.3 Traffic Impacts
HUD have undertaken an investigation into the potential operational effects on marine traffic. It has been concluded that docking and undocking of ships will not intrude into the Ma Wan Fairway and discussions are underway with the Marine Department to ensure that this is the case. Therefore, once the reclamation is complete and the dock in place there will be no further impact on marine traffic.
The land based facility will not result in any increased traffic levels on Sai Tso Wan Road as all suppliers and workers already access United via the Tsing Yi shipyard and this is unlikely tochange. Similarly, the relocation of the container storage yard to the reclamation site will not affect current traffic levels as the site will provide storage for the same number of container units as are currently delivered via the Sai Tso Wan Road. Consequently, a traffic impact assessment has not been required by the Transport Department.
5.4.4 Noise
Given the industrial nature of the area and the high proportion of heavy goods vehicles in the area, the additional noise generated by activities on the dock are not expected to be significant. Noise emissions from the operation of the dock were addressed in the previous EIA for United (Axis, 1995) where it was calculated that the average sound power level for maintenance activities was 100dB(A). The floating dock Whampoa is already moored next
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to HUD's main shipyard and the cumulative effect of the noise from operations on United is not expected to be great in an area where background noise levels are considered to be high. As there are ho sensitive receivers within a SOOm radius from the site, operational noise is not considered to be a problem. As well as distance providing attenuation of noise from the site to sensitive receivers, the site is screened to a great extent by the hills in the designated green belt on Tsing Yi.
In terms of traffic noise, the facility is not anticipated to generate any additional traffic as the container storage facility will serve the same amount of traffic and all supplies for United are already brought via Tsing Yi. Traffic noise levels from Sai Tso Wan Road will therefore remain approximately as they are. In the near future, traffic noise in the area will increase considerably once the Lantau Fixed Crossing is in use.
5.4.5 Air Quality
Air quality impacts from the dock are minimal given that every precaution is taken on the dock to minimise drift of both paint and copper slag during hull maintenance. The first EIA for United identified the generators as the only area of concern due to the requirement under the Air Pollution Control (Furnaces, ovens and chimneys) (installation and alteration) Regulations, 1989, Section 2, Regulation 2 for approval for the installation of diesel generators on board the United. At that time, approval was sought for the generators but this was not required as long as the dock was not land based. Approval will be sought for the two main I,SSOKVA generating sets, the third J,SSOKVA standby generating set and an emergency 900KV A generating set should the proposed project be allowed to proceed.
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LICENCE REQUIREMENTS
SECTION 6
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6 LICENCE REQUIREMENTS
6.1 INTRODUCTION
6.2
6.2.1
6.2.2
The operation of the United will require licensing under the Water Pollution Control Ordinance (WPCO), Chapter 358 since discharges from United will enter a gazetted Water Control Zone (WCZ). The installation of diesel generators on United as a land based facility requires approval under the Air Pollution Control Ordinance (APCO), Chapter 311, 1983. The Waste Disposal (Chemical Waste) (General) Regulations, enacted on March 18, 1992 under the Waste Disposal Ordinance, Chapter 354 also apply to the operation of United. Finally, the use of antifoulant paints containing TBTs is controlled under the Pesticides Ordinance, Chapter 133.
AIR POLLUTION CONTROL - ApPROVAL FOR THE INSTALLATION OF DIESEL GENERATORS
Introduction
The Air Pollution Control Ordinance, (Cap 311), 1983 requires industry to abate emissions of all air pollutants that may give rise to nuisance or seek prior approval from the EPD where fuel burning equipment is being newly installed or altered. The diesel generators proposed for use on the United require approval under Section 2.2 of the Air Pollution Control (furnaces, ovens and chimneys) (installation and alteration) Regulations, 1989, from the EPD Local Control Office prior to installation.
Generators on United
It is proposed that the dock will be installed with three 1550 KVA main diesel generating sets and one 900 KVA emergency generating set. The generating sets will be run on industrial diesel fuel and use an estimated 5 tons of fuel a day. Under normal operating conditions one of the three main 1550 KVA generators will be running on a continuous, 24 hour basis. When a ship docks or undocks on United it is anticipated that two of the generators will be sufficient to pump out the ballast water and to raise the floating dock. Since this process takes an estimated 2 hours and happens on average twice a week, two 1550 KVA generators will be required for a total of 16 hours per month. The third generator is required for standby purposes only. If all of the main generators fail, the 900 KVA generator will be used to provide power for the essential services.
The diesel generators are automatically controlled so that when the electrical loading capacity of one generator is exceeded a second will automatically cut in and run in parallel. In the event of an emergency, the 900 KVA generator, which will be kept on standby, will automatically cut in and supply power to all essential machinery.
Relevant information, as set out in the Regulations has already been submitted to the Tseun Wan local control office of EPD in order that approval can be sought for the installation of these generators on "United".
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6.3 WATER POLLUTION CONTROL ORDINANCE - ApPLICATION FOR A DISCHARGE LICENCE.
6.3.1 Introduction
The existing discharge licence is attached as Appendix 2 and WQOs for the Western Buffer WCZ are attached as Appendix 3. The effluents to be discharged from United into the Western Buffer WCZ and which, as a result, require licensing are:
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The release of treated sewage effluent from the Hamworthy sewage treatment unit on board United; and
The discharge of TBTs and other contaminants in the washwater, or the discharge of filtered water from the shore following implementation of a collection and filtering system.
6.3.2 Sewage effluent
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• Suspended Solids 40mg/l; and
• Total coliforms (MPN) 2001100 m!.
The effluent is discharged from above the water surface and the average daily volume of effluent discharged is expected to be less than 4000 litres. The United will be the first floating dock in the area to house its own sewage treatment unit.
6.3.3 Discharges of toxicants
Discharges to the marine environment of greatest concern have been identified as wash water and storm water run off due to the contamination with TBTs and other contaminants such as copper and zinc. This discharge is largely a result of the washing down of a ship's hull prior to painting and maintenance work, and the washing down of the dock following the removal and application of paint.
It is anticipated that the current discharge licence for United will only reqUIre mInor ammendments.
6.4 WASTE DISPOSAL ORDINANCE - REGISTRATION AS A CHEMICAL WASTE PRODUCER, COLLECTOR AND TRANSPORTER
6.4.1 Introduction
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6.4.2 Chemical Waste produced on and collected from "United"
HUD are currently licensed to produce, transport and collect chemical waste under the Waste Disposal (Chemical Waste) (General) Regulations. Up until recently, this license included HUD's Tsing Yi site, the Tsing Yi and the Taikoo.
Recently the license has been amended to include likely waste arising from the operations on "United". Chemical waste includes waste mineral oil, lubricating oil, oily sludges, contaminated bilge water, and waste material containing TBTs. Drums containing chemical waste will be temporarily stored in a designated storage area on the working platform until they are transported ashore by the work boat which is licensed to collect and transport to HUD's onshore facility at Tsing Yi.
Licences will be amended by HUD should the relocation be approved.
6.5 PESTICIDE CONTROL ORDINANCE - PERMIT TO USE TBT BASED PAINTS
6.5.1 Introduction
The use of TBT based antifoulants is covered in the provisions of the Pesticides Ordinance. In accordance with this ordinance, the Director of Agriculture and Fisheries (AFD) is empowered to regulate the use of "inert ingredients" of toxicological concern in pesticides. This involves registration of pesticides; issuing of licences to import, formulate etc registered pesticides, and the issuing of permits to import, formulate, store, trade in and use unregistered pesticides. Users are required to hold a permit for each type ofTBT paint used.
6.5.2 Permission for Use ofTBT paints
HUD are currently registered with AFD as users of TBT based paints. HUD have been granted seven permits which allow them to use different formulations of TBT based paints. Each permit states the maximum allowable concentration of TBT, Copper (I) Oxide and Zineb where appropriate.
AFD have recently issued a new application form for a permit to use pesticides and this will be filled by HUD accordingly.
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ENVIRONMENTAL MONITORING AND AUDIT
SECTION 7
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7.0
7.1
ENVIRONMENTAL MONITORING AND AUDIT
INTRODUCTION
Environmental monitoring and audit (EM&A) procedures are essential in order to:
• ensure that any environmental impacts resulting from the construction and operational phases of the proposed project are minimised and kept to acceptable levels;
• establish procedures for checking that the proposed mitigation measures are applied and are effective, or that appropriate corrective actions are undertaken if and when required;
• provide a means of checking complilmce with environmental objectives, recording anomolies and documenting corrective action.
This section outlines the framework of the EM&A including the scope, responsibilities and reporting requirements. Full details of the proposed EM&A will be produced in the form of an EM&A manual.
7.2 TECHNICAUPERSONNEL REQUIREMENTS
Hongkong United Dockyards Ltd will be responsible for ensuring that the EM&A requirements are met during the construction of the reclamation and operation of United Dock. The EM&A work will be carried out by an independent environmental team consisting of suitably qualified and experienced personnel. The EM&A team leader will produce regular reports of the EM&A findings and will also take a proactive approach advising either the site manager during construction or HUD's Marine Manager during operation on potential problems and possible solutions.
7.2.1 EM&A Manual
On approval of this project HUD will be responsible for preparing an EM&A manual which will be submitted to the EPD. The manual will include the following:
• Construction programme;
• Overview of potential environmental impacts and rationale behind the EM&A programme;
• Location of sensitive receivers;
• Location, frequency and type of EM&A required to assess the impacts of the construction and operation of the project;
• Event contingency plans/action plans for water and sediment quality impacts;
• Analytical procedures and equipment required;
• Reporting procedure including presentation of monitoring data .and audit results, frequency of submission etc;
• Complaints/consultation procedures.
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7.2.2 Reporting
7.3
A periodic EM&A report will be prepared by the independent environmental monitoring team and submitted to HUD and the EPD. The frequency of reporting during each phase of the project will be agreed with the EPD.
For the operational phase it is recommended that a similar procedure of reporting is followed as has been undertaken while the dock has been moored at Yam 0 Wan. Factual reports containing monitoring data and audit findings will be produced as information is obtained and a concise account of the EM&A undertaken over the period of the discharge licence is prepared prior to licence renewal.
The reports for both the construction phase and operational phase EM&A will include the following:
• Project Description - A synopsis of the project and impacts of concern
• EM&A Requirements - Summary of the parameters measured and the programme followed including equipment, locations, duration and frequency of monitoring.
• Monitoring results - location, parameters, date, time, environmental conditions etc,
• Audit Results - review of pollution sources, working procedures, non compliance, follow up actions and procedures etc.
• Complaints - liaison and consultation undertaken and subsequent action.
• Discussion and Conclusions
• Appendices - full set of monitoring results, standards and guidelines etc
CONSTRUCTION PHASE MONITORING
Compliance monitoring should be undertaken throughout the dredging and reclamation phase of the project to monitor sediment disturbance and particulate release. Key parameters to be measured are dissolved oxygen, suspended solids and turbidity as these will be indicative of the impacts of the sediment plume.
In addition to this monitoring, elutriate tests are currently being undertaken on five of the most contaminated sediment samples taken during the site survey. This will provide information which will help to determine the fate of the key metals found in the sediment during dredging.
7.3.1 Sample Location
Baseline monitoring will be necessary to establish 2 control stations, one upstream and the other downstream of the site prior to the commencement of construction works. In addition to the control stations 2-3 stations will be monitored within the area expected to be affected by the sediment plume.
Elutriate tests are currently being undertaken on all samples previously taken where grade C contamination was found. The only metals present in concentrations large enough to classify the sediment as grade C are copper and zinc. These are vibrocore 1 and 4 and grab 1,4 and 5.
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7.3.2 Sampling Frequency and Methodology
7.4
Monitoring will then be undertaken at a frequency to be agreed with EPD and set out in the manual. Water samples will be taken using a standard 2 litre water sampler and using a metre to measure turbidity and dissolved oxygen in situ.
Baseline data will be used together with Water Quality Objectives for the Western Buffer Water Control Zone (Appendix 3) to determine a Compliance level which should not be exceeded and an Action level to initiate action to prevent a breach of the Compliance level. Table 7.1 sets out proposed event contingency plan for exceedances of Action and Compliance levels. Event Contingency Plans must be followed by the contractor to facilitate an immediate response in the event that Action levels are exceeded.
Monitoring data will be sent to EPD on a regular basis throughout the construction period and EPD will be advised of any exceedances.
Elutriate tests follow USEPA methodology and will use sea water taken from the Tsing Yi site to determine the effect of disturbance of sediment in the water on the release of copper and zinc. Metals in the elutriate will be analysed by a HOKLAS accredited laboratory.
OPERATIONAL PHASE MONITORING
During the operation of the dock it is proposed that monitoring of sediments and marine waters continues around United once it is relocated to Tsing Yi. Monitoring should include heavy metals and TBTs. Preliminary tests on the effluent collected should be undertaken before and after filtering in order to determine the effectiveness of the system.
7.4.1 Monitoring Locations
Monitoring positions for marine sediments will be set out in the EM&A manual and it is proposed that they follow the pattern used by CES in the study of TBTs in this area for the EPD (CES,1995). These positions follow the circulation in the area and will therefore enable monitoring of dispersion caused by the fast currents to the west of the embayment. Marine water quality wiIl also be monitored close to the point of discharge from the treatment tank between the docks and 50m down current of the dock. Baseline monitoring will first be undertaken at these sites prior to the commencement of operations.
The washwaters will be sampled prior to filtering and after filtering before it is released into the marine environment in order to assess the effectiveness of the collection system.
The dock is currently adversely affecting sediment at Yam 0 Wan. Removal of the dock from this area will therefore have a beneficial effect on sediment quality as TBTs degrade. TBTs are not persistent in the environment and will break down into dibutyl and harmless monobutyl tins over a period of several weeks depending on the conditions (Mora et aI, 1995). It is recommended that the sediment monitoring programme continues in Yam 0 Wan for a limited period as part of the site decommissioning to determine the rate of breakdown ofTBTs that have accumulated in the area and to understand the process in Hong Kong more clearly.
7.4.2 Sampling Methodology
Waters will be analysed for TBTs and, as for the ongoing EM&A work for United, will be sampled from the marine environment using a standard 2 litre water sampler from which a 1
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litre sample can be poured into a glass/polycarbonate jar and sealed with a Teflon lined lid. Waters entering the treatment system will be sampled directly into a glass/polycarbonate jar. Waters will be tested for TBT and suspended solids.
Sediment samples will be taken using a Van Veen O.OSm2 grab sampler which will be carefully lowered down to the seabed where a surface sample will be taken. The sample will then be carefully brought to the surface where the sample will be emptied into a bucket and subsampled. Sediment will be placed in polycarbonate jars and stored at below 4°C until analysis. Sediment samples will be sent to a HOKLAS accredited laboratory for metal (As, Cd, Cr, Cu, Pb, Ni, Zn and Sn) analysis and to a laboratory approved by the EPD for TBT analysis. Analysis will be in line with that used by CSIRO as detailed in Appendix 7.
7.4.3 Sampling Frequency
Frequency of sampling will be agreed with EPD prior to the submission of the EM&A manual. It is recommended that monitoring of waters and sediments should continue every four months subject to review and commencing just after the dock is relocated. The period over which the dock is monitored will also be subject to agreement with the EPD. The dock is currently subject to a two year EM&A programme after which the results were to be used for the review of the discharge licence.
In the Yam 0 Wan area monitoring should continue every four months for a limited period to determine breakdown of TBTs. Analysis should include Tributyl tins, dibutyl tins and monobutyl tins. Problems may however be experienced in interpreting these results accurately as other floating docks in the area will continue to contribute to levels of TBTs in the area and so the pattern will not represent a breakdown of TBTs from the date that United ceases to operate in that area.
In addition to the above EM&A recommendations, discharges into the Western Buffer water control zone will be monitored in accordance with the discharge licence requirements. HUD's current require a sample to be taken every time a TBT treated shipl unknown treated ship is in for repair. Also monthly sampling of process waters are required for metals, suspended solids, oil and grease. The monitoring location will depend on the outcome of HUD's current feasibility studies which are investigating suitable collection and treatment systems. Once such a system is in place the point of discharge will change. The sewage treatment plant effluent will also require weekly analysis of residual chlorine.
7.5 ENVIRONMENTAL AUDIT
The purpose of environmental auditing is to review the effectiveness of the environmental protection programme being undertaken i.e through monitoring and mitigation. Records of environmental monitoring should be reviewed during the audit to check:
• Records of monitoring procedures;
• Records of monitoring results;
• Records of exceedance of regulatory limits (WQOs I Effluent discharge criteria I requirements of discharge licence etc);
• Details of mitigation measures undertaken;
• Effectiveness of Environmental Monitoring programme.
The operational procedures are currently audited on an annual basis to ensure that the requirements of the EIA, discharge licence and operations manual. It is recommended that
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these audits continue as they are a useful way of reviewing data, procedures and operations as well as identifying problems and providing practical solutions.
7.5.1 Constrnction Phase Anditing
Throughout the construction period monitoring data will be checked on a regular basis and as stated above, a proactive approach taken to ensure that the contractor can minimise environmental impact during the dredging and reclamation.
7.5.2 Operational Phase Auditing
It is proposed that aUditing continues on an annual basis for the operation of the dock and checks all procedures set out in the operational manual for the dock and requirements set out in the discharge licence for the dock. The first audit will be undertaken within 3 months of the commencement of operations on the dock in' Tsing Yi in order to investigate the effectiveness of the treatment system.
Perhaps most importantly, the audit will seek to check and advise on improvements to housekeeping measures used on the dock as these alone can significantly reduce loss of contaminants to the marine environment. In particular, ways to remove as much of the copper slag and paint from the dock floor as possible should be investigated and alternatives to copper slag should continue to be investigated.
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Table 7.1 Water Qnality Monitoring Event Contingency Plan
EVENT ACTION
Exceedance of:
COllsultant
ACTION LEVEL Infonn EPD, AFD, contractor/operator; resampJe to continn result
Increase frequency of monitoring
Propose remedial action
Continue monitoring after completion of remedial action to con finn action is effective
Record event in monitoring report for submission to contractor and EPD
COMPLIANCE Infonn EPD, AFD, contractor/operator; LEVEL
Confinn result & increase monitoring frequency
Propose remedial action
Undertake monitoring at nearest water quality SR
Continue monitoring after completion of remedial action to confirm action is effective
Complete Monitoring Report and submit to contractor/developer and EPD
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Check working meteods/practices to identify any immediate causes; take appropriate remedial action if necessary
Undertake detailed check of working methods and practices
Carry out appropriate remedial action and infonn EPD of remedial action
Ensure corrective action has been undertaken and is effective
Amend method statement, if appropriate
Undertake immediate check of activities and employ any appropriate mitigation
Ensure immediate implementation of remedial action and in extreme cases cease activities
Ensure corrective action has been undertaken and is effective and infonn EPD of remedial action
Amend method statement, if appropriate
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CONCLUSIONS
SECTION 8
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Hongkong United Dockyards Ltd - Extension to TITL I08RP Proposed reclamation and relocation of United Floating Dock Environmental Impact Assessment - Final Report
8 CONCLUSIONS
The intention of the project is to provide access and a mooring facility for the United dock which, if the project is approved will be relocated from Yam 0 wan in North Lantau to HUD's existing facility at Tsing Yi, adjacent to the Whampoa dock.
The proposed works will involve a small reclamation and a limited amount of dredging to prepare the site for the mooring of United. Based on the findings of the EIA it is considered that the construction phase of the project will have minimal environmental impact provided that the recommended mitigation measures are followed and monitoring is undertaken throughout the construction period to ensure that any deleterious effects on marine water quality can be detected at an early stage and corrective action taken. The only identified sensitive receivers which could be potentially affected by the construction work are gazetted beaches which are currently not of concern due to the current poor bathing water quality due to sewage.
The key issue of the project is the release of contaminants from the dock into the marine environment during the operational phase. Since the dock is currently operating under licence in Yam 0 Wan this assessment has provided a comparison of the current situation with the future scenario. EM&A work which has been ongoing for the past 12 months indicates that the dock is adversely affecting marine sediments and waters in North Lantau. While the dock remains in this area the only mitigation possible is to ensure that good housekeeping measures are undertaken at all times to minimise the release of contaminants contained in paint flakes, spent grit and other waste that may accumulate on the dock floor. The EM&A work has ensured that good house keeping measures have been implemented on the dock but analytical results have indicated that these are not sufficient to prevent copper, zinc and TBT accumulating in the sediments. TBT is of particular concern as it has the ability to harm non target marine organisms at very low concentrations.
The comparison between the two sites, Yam 0 wan and Tsing Yi included a limited amount of plume dispersion modelling. Tsing Yi was found to be the favoured location since there are no Fish Culture Zones affected by the plume, the effluent does not have the potential to affect waters used by the Chinese White Dolphin and the area over which peak deposition of contaminants occurs is smaller than that in Yam 0 Wan. The plume released from the dock in Tsing Yi could, over time contaminate sediments off gazetted beaches. The land based mooring of United at Tsing Yi will enable HUD to collect the wash waters to remove a significant proportion of contaminants through filtering thus minimising impact on the marine environment in general and gazetted bathing beaches. The proposed reclamation will provide the land area on which a treatment tank can be installed to collect between 200-400 tonnes of water from the dock.
Once the construction of the mooring site at Tsing Yi is complete, relocation of the dock has several environmental benefits which are summarised below:
• Installation of a collection and treatment system thereby reducing TBT, copper and zinc release from the United Dock and reducing environmental impact;
• Transfer of dockyard activities from Yam 0 Wan to Tsing Yi, a less sensitive area in terms of ecology;
• Improved safety on the dock in terms of emergency services and minimising distances over which chemicals and waste needs to be transported;
Axis Environmental Consultants Ltd AJCV15131192-000 Page ./8
Hongkong United Dockyards Ltd· Extension to TYTL 108RP Proposed reclamation and relocation of United Floating Dock Environmental Impact Assessment - Final Report
• Improved efficiency of dockyard activities through mooring dock adjacent to main shipyard allowing decommissioning of Taikoo in Yam 0 Wan and therefore reducing overall TBT input into Hong Kong Waters;
• Extension of proposed collection system to include washwater from Whampoa dock so that all of HUD's docks will use best practical means for minimising environmental impact.
8.2 RECOMMENDATIONS
• It is recommended that the proposed project be allowed to proceed given that this can result in significant improvements to the current practices on the· dock which will result in a reduction in TBT release to the marine environment.
• HUD should continue with the design of the collection and filtration system which will remove all paint chips, copper slag and suspended solids from the discharge.
• A monitoring and· audit programme should continue for United to monitor the effectiveness of collecting the washwater and to monitor accumulation of contaminants in sediments around the dock.
Axis Environmental Consultants Ltd AXV/5/3//92-000 Page 49
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I-/ongkong United Dockyards Ltd - Extension to TYTL I08RP Proposed reclamation and relocation of Uniled Floating Dock Environmental Impact Assessment - Final Report
REFERENCES
Axis Environmental Consultants, (January 1995) Final Initial Assessment Report for the mooring of a 40,000 tonne lifting capacity Floating Dock, United.
Axis Environmental Consultants, (March 1995) Final Report, Environmental Impact Assessment for the mooring of a 40,000 tonne lifting capacity Floating Dock, United.
Axis Environmental Consultants, (June 1995) EM&A Manual, Environmental Impact Assessment for the mooring of a 40,000 tonne lifting capacity Floating Dock, United.
Axis Environmental Consultants Ltd, (December, 1995) Inception Report for EIA for the Reclamation and Relocation of United to Tsing Vi.
Carpenter R.A & J E Maragos (1989) How to Assess Environmental Impacts on Tropical Islands and Coastal Areas.
CES (Asia) Ltd, (1995) Tributyl Tins Contamination in Coastal Sediments of Hong Kong (for the EPD)
Dirkx W, R Lobinski, M Ceulemans and F Adams (1993) Determination of methyl-and butyltin compounds in waters of the Antwerp harbour. In The Science of the Total Environment 136 pp279-300. Elsevier Publications B.V Amsterdam
Eastern Express (15th Jan 1996) Change at a Snail's Pace.
Goldberg, E.D (1988) Information needs for Marine Pollution Studies. In: Environmental Monitoring and Assessment II; pp293 - 298
Harris J R W, C.C Hamlin & A.R.D Stebbing, 1991. A Simulation Study of the Effectiveness of Legislation and Improved Dockyard Practice Reducing TBT Concentrations in the Tamar Estuary. In Marine Environmental Research 32 pp. 279-292. Pubd Elsevier Science Publishers GB.
Haskoning Royal Dutch Consulting Engineers and Architects (1989) Technical and Economic aspects of measures to Reduce Water Pollution caused by the Discharge of Tributyl Tin Compounds. Report prepared for the European Commission
Hong Kong Government, (1991) Environmental Guidelines for Planning in Hong Kong
Mak Y. M and S T Hawkins (1996) TBT contamination in Hong Kong - A survey of Imposex in Thais clavigera. Paper presented at the Asia Pacific Conference on Science and Management of Coastal Environment 25-28 June 1996.
de Mora S J, C Stewart and D Phillips (1995) Sources and Rate of Degradation ofTri n-butyl tin in Marine Sediments Near Auckland, New Zealand. Elsevier Science, Vol 30, No I, January 1995.
Tolosa I., L. Merlini, N. E Bertrand, J.M Bayona (1992) Environmental Chemistry, Occurrence and Fate of Tributyl and Triphenyltin Compounds in Western Mediterranean Coastal Encolsures). In Environmental Toxicology and Chemistry, Vol II, ppI45-155.
Axis Environmental Consultants Ltd AXVJ5J3/J92-000 Page jO
Hongkong United Dockyards Ltd - Extension to ITTL I08RP Proposed reclamation and relocation of United Floating Dock Environmental Impact Assessment - Final Report
World Health Organisation (1989). Environmental Health Criteria 116; Tributyl Tin Compounds. Published under the joint sponsorship of UNEP and the International Labour Organisation and WHO.
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WORKS BRANCH TECHNICAL CIRCULAR No 10195
ApPENDIX 1
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Ref: WB (W) WORKS BRANCH GOVERNMENT SECRETARIAT MURRAY BUILDING GARDEN ROAD HONG KONG
10 May 1995
Works Branch Technical Circular No. 10/95
Importance of Sand from the People's Republic of China by Barges
Introduction
The importation of sand from the People's Republic of China (PRC) by barges has increased dramatically over the past two years Initially, many of these barges failed to comply with Hong Kong regulations and, in some cases, they apparently failed to comply with some PRC regulations. Recent cross-border efforts have helped to regularise the approaches of the authorities on both sides of the border. In Hong Kong, the Marine Department, marine Police, Customs & Excise Department and Immigration Department have reduced the numbers of illegal operatives. However, there is further scope for improving control on these sand barges by the incorporation of a suitable Particular Specification in reclamation contracts.
New Standard Particular Specification
2. Attached at Appendix A is a new Particular Specification which must be included in all reclamation or other contracts which might iuvolve the importatiou of sand from PRC by barges.
3. Attached at Appendix B is the current list of permits for which origiual versions are required by both PRC and Houg Kong authorities, to be carried on board sand barges. This list changes from time to time and if in doubt, the Engineer for the Contract should consult the relevant Hong Kong Government Department. The Director of Marine can also provide confirmation of the relevant documents required by PRC authorities.
(J Collier)
Deputy Secretary (Works Policy)
AXK6741192000
(I)
(2)
(3)
(4)
Appendix A
Particnlar Specification
Importation of Sand from the People's Republic of China by Barges
Where the Contractor intends to import sand from the People's Republic of China (PRC) by barges, he shall submit to the Engineer for approval a proposal containing the information as referred to in sub-clause (2) of this PS for the delivery of sand from any source in PRC waters to the Site at least 28 days prior to its delivery. The Contractor shall, within a reasonable time of being required to do so, provide to the Engineer such further particulars as may be required by the Engineer to enable the Engineer to make a proper decision on the proposal. Approval by the Engineer shall not relieve the Contractor of any obligation or liability under the Contract.
The proposal shall contain the following information
(a) The source of the sand, grading curves and test results for contamination of heavy metals or any other test required by the Engineer or as are necessary to confirm compliance with the Specification.
(b)
(c)
The name and licence number of each barge to be engaged in transporting the sand, and the company name, address, telephone and fax number and contact person of their appointed Hong Kong shipping agent.
Details of all permits and authorizations, original versions of which the relevant PRC and Hong Kong authorities require to be carried on each barge.
All sand imported from PRC for incorporation into the Works shall be obtained from the source approved under sub-clause (I) of this PS.
On each occasion sand is delivered by barge to the Site, the Contractor shall produce to the satisfaction of the Engineer documentary evidence that the sand is from the source approved under sub-clause (1) ofthis PS.
AXK6741192000
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List of documents, original versions of which are normally required by Hong Kong and PRC authorities and to be
carried on barges transporting sand from PRC
PRe Authorities
I. Certificate of Ship Nationality
2. Certificate of Survey
3. Certificate of Navigation (HK, Macau and PRC)
4.
5.
6.
7.
Route Approval
Clearance Certificate
Pass for entering HK and Macau
Custom Supervision Book of Small Craft (HK, Macau and PRC)
8. Master and Chief Engineer Certificates
9. Seamans' ID CardslRecord Books
10. Permit for Sand Exportation
Houg Kong Authorities
I.
2.
3.
4.
5.
6.
Arrival Report (Marine Dept)
Arrival Clearance, Vessel and Crew (Imm Dept)
Cargo Manifest (Customs & Excise Dept)
Sand Permit (Civil Engineering Dept)
Departure Clearance (Marine Dept)
Departure Clearance (Imm Dept)
AXK6741192000
Appendix B
CURRENT DISCHARGE LICENCE FOR UNITED IN
THE NORTH WEST WATER CONTROL ZONE
ApPENDIX 2
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ENVIRONMENTAL PROTECTION DEPARTMENT 11;i m i!?:, ~ ~,
WATER POLLUTION CONTROL ORDINANCE 7.1<. r'i * 'ffi' flitl H~ {jlJ
North Western Water Control Zone i1Si ~~ ill" 7.1<. ~r 'ifr H;tl illi LICENCE PURSUANT TO SECTION 20
:!-J(*¥ .. !H§l/W = -1- ~~~ii'i1n':JJ~R({
Licence No, ~ 00 III Ilk
, EP 742/974/017 1
o Whereas an appl ication under Section 19 of the Water Pollution Control Ordinance was received from IIONGKONG UNITED DOCKYARD LIMITED for the discharge
[Originating from _flo_~ .. ~_Lng P_9ck "United", Yam 0 Wan, North [antau Island, N,T.
lin North Western water (ontrol Zone, the Director of Environmental Protection (hereinafter called "the Authority·), pursuant to Section 20 of ~he Ordinance, grants
[thiS Licence subject to the terms and conditions stated herein. '
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3 1 AUG' 1995 ~~ ~.-~-
[Date ( ., )
• For the Authority 8M WM&~( ~ •• ttff)
, ischarge Category Industrial >" to. fiji !iji -lature of Trade/ floating Dock Business
ti' ~
~ature of Discharge Effluents arising from (a) domestic sewage and WI' tt.c 1'1 ~ (b) maintenance of vessels
treatment faci lit i es For (a~ : Screening, aeration, sedimentation and chlorinati,on r~ :l!jl ® Ii&! for (b Heavy metal and oi I and grease removal
lischarge Point &: Discharge Points for ~~~ ~ (b) : discharge into marine waters Samp ling Point Sampl ing Point for sampling valve of sewage treatment t1~ JtJ. !Y1i & l!X. {.t ~Ii plant
for (b) . drain holes of the floating dock
• delete if [Hm :E/ICI
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. PART B : STANDARD CONDlTI IONS ./ *V-----:-lf,jrl1lfW\!r,-· _(.....J_t.(~
1. Limitations on.discharge f}"'&~Wlitl
1.1 The maximum allowable flow rate from domestic sewage and maintenence of vessels .. . V_ and. .250 cubic metre per day respectively. {j~T*EI~t:7;!;TI*.&19WMm'(I'Jl'&;\ijifrtti1r.~mD 11 fn._f~:rr/:i* 0
are
1.2 The quantity and composition of the discharge from domestic sewage (A) and maintenance of vessels (B) shall not exceed any of the maximum standards stated in the table below. These standards are expressed as concentrations in milligramme
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Determ-i-nands Maximum ~~/},;l-=f .L-. r For
Flow Rate (Cu.m/day) 11 ff,j;.1il: (:l1:1i*/flJ EI )
pH (pH un i ts) M~jlli[ 6-10
Temperature (·c) ~wJJt 45
Suspended Solids 500 !~mQloo
Biochemical Oxygen Demand
500
15 days, 20·C) J=,{~W$\i1: (5 ~. 20·c)
Chemical -Oxygen Demand {~*fm~t!t
1000
Oil &: Grease nilDID 50
Total Residual Chlorine 1 M~~(}i~
Surfactants (total) 30 J<iTIi1i!itlJ!ltl (t'~ill:)
Colour (Lovibondunits) 4 ~5mm cell len~h) I'~ (tZllMllJ!M:'1 "i!l~llj-) (25~' .*J'tHt'irr ') .
E.coli (count/l00ml) ::k1w.J;t!j!\tilj (fflil/lOO~1'I-)
4000
Iron ~.n 20
N/A Not applicable l' ~ fa
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Vt:a:;0:r J: ~H For A
_1: ~l* For B
250 Boron &: Barium 6 4 individually jWl'iJUm.L&~
6-10 Lead ~ 2 1.2
-15 S i I Ver !iH 2 1.2
500 Nickel ~ 2 1.2
Arsenic Tiill 2 1.2 500
Chromium ~/ 2 1.2
0.1 Mercury &: Cadmium 0.1 individually
1000 iIIiI'iJU~lt&~\l
Copper W- 2 1.2
50 Selenium l~ 2 1.2
1 Other toxic Metals /" 2 1.2
20·
individually Jljt!3 fUJI)jIWJf~W~$
Total Toxic Metals 4 2.4 ~~:(;s."'~},{J Io..-'El,t: _
1 Sulphide Wit{t~..a 5 5
Cyanide \li\{t~J 1 0.5
Phenols ~ 0.5 0.5 4000
Total Nitrogen tt1~ 100 . 80
13 iotal Phosphorus ~~1iM 10 8
- 2 - Form TE/ICI
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For the purposes of determining compliance with the standards stated in Condition 1.2, samples shal I be taken at the Sampling Point(s) or any other points from which the samples so taken are regarded by the Authority as being representative of the qual ity of the discharge. When any single sample analyzed for a determinand is greater than the corresponding maximum concentration set out in the table above, the discharge is deemed to have fai led to comply with the Condi·tion 1.2. The flow rate shal J be determined in accordance with Condition 4.
~~~~*m~~~~S.I.2~~~~~rn~~a~,~~~e~~~~s~rr~mm ~ 'hI PJ:IlIIl/X f!l ffi!. {-t3!i{I1AJ'J{~* niJ {f:friS;¥f; It!! f!'L ~JllJlfXtl~* 0 'ia'f/ilJ Witt'} R~tF.{~r$~ ffli!t**J/& ~ .p , iilH'l'lHriJ - ffM~~~FY. B~Jit~JSt~~liSJ:~ PTrfflJ (I''J:f\::lf\U:~H.lf,j , F1HM& A''lr57.l<flfl1J:Z:~~i.j?i l' 11~m 1 • 2 ~l~ 0 ~JiS01i::lli:MJfff<l~;C1:Tf.b'i'ditR\Uff 4 JJi~~;:o,:I~QiJ;t:lIJ:E 0
C 2. Ge'neral Prohibitions D-n!i~HjiJ
2.1 The discharge shal I not contain any substances such as polychlorinated biphenyls ( PCB), polyaromatic hydrocarbon ( PAil), f~migant, pesticide or toxicant,
[ . radioactive substances, chlorinated hydrocarbons, flammable or toxic solvents, petroleum oil Or tar, calcium carbide, waste I iable to form scum, deposits or discolouration in any part of the waters of Hong Kong; and sludge, floatable
[J substances or solids larger than 10 mm.
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[2.2 No discharge shall bypass its Sampling Point (S.P.) or Discharge Point (D.P.)
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2.3 Di lution of the discharge in any May to achieve campi iance with the contained in this I icence is prohibited. However, this does not prohibit mixing different effluent streams within the floating dock.
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I imi tations necessarily
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The licensee shall provide and maintain suitable facility such as an inspection chamber, manhole or sampl ing valve at each Sampling Point(s) (S,P.). The facil ity shal I be so constructed and maintained as to enable duly authorised officers of the Authority to take samples at any time of the discharge from the said floating dock. The I ieensee shal I col leet samples of the discharge at the Sampling Point and, at his own expense, analyse for their composition in the manner as from time to time required in writing by the Authority.
[.f,f)\I\!J...3Jl{r:1ll-(!6ilfXfJl!!!Mi9:~1EdfUg~'mfl~aJl:.li0i , 1?ljttrl~~NJ , ?HI:Ii~Itxf*rlij , ~lnffW:~'Ef . ruiJ~.~~~Aa~~~tr~~~~h~~~*~*o~MA~M~~~.~.wm~~~~ , ffI{X~lMlIllltttl* , ~(L g ~(~~.&.7Hrri'J*A<.JJRt) • l Form TE/ICI - 3 -
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th Flow Measurement ill F£t. m;: :Ilk
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The licensee shal I determine the dai Iy rate of discharge by either, ~~IA~~~T~K~-~WD~~m~~Bill~hM: [
(i) providing, instal I ing and. maintaining a continuous flow measuring device with an accuracy certified by its manufacturer to be within plus or minus 3 [, percent, and shal I cal ibrate the flow measuring device regularly according _ to manufacturer'S recommendations; Of,
( i i )
f&ii('t. , MtH'FliU1H~-WHlJf~t'fKif,tfLl:l!I' , JPV\rrt'af'lTJ[~iNf.[~iili~ijlifrWriVfJt1jJlh~{!&t& (l:l ~if,t~~3%oM~Agkma •• ~Qm.~~m.~~mUfta~;.
o if no such device is provided, the flow rate shall be calculated, through [J using methods approved in writing by the Authority, by making reference to the amount of water used in the said floating dock being served by mains [, supply and other sourceS, less process consumption and any other losses.
i('~fnutMm~frd!-I'::m , m;;iiI1~~!Kl'm'~11U'ii1[1~'j,!iflliil1tlIfiO/'1jj'~.t , ~JHj.f1~~r-t'B}lj I~I **»'11; ~*.~.m*.N*W.~~I~m*~=~M*M*H.o
[ 5. Reporting o ,..-, lb
:l-D( 1=1
The I icensee shall the discharge in avai lable at all Authority. Copies request.
keep records of the flow fate, nature and composition of [ such form as the Authority may require and shall make them times for inspection by duly authorised officers of the' of such' records shall be submitted to the Authority upon [
W~Am •• w~.e~m~,gff~*~.,K.&.~~.M,~ ••• ~ •• ~. ~A.~ •• ~oft •• ~~.&*,*2ae.~*o [
6. Notification of change 11! c& ~i!1 9.t1 [
7.
7.1
The licensee shal I notify the Authority in writing of any changes or proposed changes in the processes of manufacture or the nature of the raw materials [ used or of any other circumstances which may alter the nature and composition of the discharge or may result in the permanent cessation of the discharge.
A~~~ffl~A~&~.~~~~~~*,~fflffi~M~~~,~#XM~~&.~R* ~ A/~'/1, 'Dlf i.ltJiQ;{~Hi~!ttJ& 1'fl.}M'J&n\I!jJiW , ~~:(,\fm; :ii!l9.il'B'fJiiJ w,r'}../l} 0
Entry and Inspection A i):l ill ~
l Authorised officer(s) of the Authority shal I be al lowed to enter upon the said l~ floating dock for the purposes of inspection, sampl ing, records examination or any other duties authorised by Section 38 of the Ordiance.
Porm TE/ICI - 4 -[
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Where the I icensee has security measures in force which would require prQper [denti fication and clearance before entry into the said floating dock, the licensee shal I make necessary arrangements such that upon presentation of evidence of identity and of authorization, a duly authorised officer wil I be permitted to enter, without delay, for the purposes of performing his duties.
Part C: SPECIAL CONDITIONS 01 ffl\ : f!f 1iU £15:
o 8. Treatment
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The I icensee shall provide necessary wastewater treatment and shal I at al I times properly operate and maintain all faci I ities and .systems of treatment which are installed to achieve campi iance with the conditions of this licence.
'Treatment shall .include but shall not be I imited to heavJ._!II~,-"tc:.a-,-l...:a,",n-,,-d __ _ __ 2.0 and grease (~J!I",o-,-va""I,--,. __ .
ro~A~ •• ~~~R* ••• ~~~~~~ •• ~~ •• ffi#a~a*~oo.~~m~ a~ t~ * r~ llJ! llll:niii ~ * *it 0 JJ!lJlJt J:j' ~ IlL!! t!!. tMI'!. tlfl1' lUi ~'&1t ill ~:~nU!lJ om n3 '* M 0
The licensee shal I engage personnel with adequate qual ification and experience to operate and maintain the ~reatment· system.
Disposal ~~
Sol ids,' sludges, chemical wastes, oil and grease, filter backwash, or other pollutants removed in the course of treatment shall be disposed of· in the proper manner such as to prevent any such materials from entering waters of Hong Kong. Standby equipment shal I be provided to guard against failure of major treatment equipment.
.~ •• ~~m,~~,~ •• ~,~~,~.B~&~X~~*~, •• ~~mm,~ W~~.~Ma~.M*.o~H •• m.~E~&ft.~,~WM~.m~o Bypass of treatment facil ities shal I be prohibited unless it is unavoidable to prevent· loss of I ife, personal injury, or severe property damage or no feasibJ e al ternatives exists, and the I icensee shall inform the Authori ty thereof in writing and prove to the Authority.
~)~m~AG~~*ffiffiM~~m~~.x~~fr~~m$,M*~~.m~.~* •• H!.tJiQi}JI:1& 0 ffl Ii!\! Xtr:f5'7.l<Mlml~&Hfllt;j '9'~liiJ~Ktttf:W5(t.LfTfiiJiJJj,ll N: iRr. ~J:l 0
Form TEIICI
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9.3 Al I sludge, sol ids and other waste matters arisen from treatment of domesti~sewage shal I be :
(i) treated and disposed of in a manner with prior written approval from the Author i ty ; or
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(i i) subject to acceptance of the government sewage treatment works, tankered OJ, away at regular intervals for disposal at the works.
The licensee shall keep record of the quantities and dates of al I such removal operations in a log book and whenever required produce it for examination and retention by the Authority.
10. Operation Manual £Ii'! it =f- 1111-
The licensee shal I prepare an operation manual which shal I include. as a mInImum. operating procedures, inspection programme and repair and maintenance programme for the treatment system. The operation manual shall be kept at the treatment plant and a copy of the manual shall be submitted to the Authority.
11. Waste Segregation and Spill Prevention ~PIl ~~ ~ 7.l< .& ItJj Jl: ~ ~~
11.1 Spent chemicals, chemical wastes, or substances prohibited under this licence shall be segregated from the wastestream of the discharge and shal I be treated and disposed of in the proper ·manner such as to prevent such substances from entering the sewerage system or waters of Hong Kong.
11.2 The licensee shal I take al I necessary measures to control and prevent spillage or leakage of these chemicals or substances. These shall include, but shall not be I imited to, good housekeeping to maintain a clean and orderly working environment, regular inspection of equipment and process operations, and provision of containment facil ities to contain or capture releases of spil I or leakage within the said floating dock.
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Additional Monitoring and Reporting Requirements 'N ))[1 n<l fit.: illU "& * ~ HI. !E
[ 12.1 The I icensee shall install an automatic sampl ing device when required, and sample the discharge at the Sampl ing Point(s) and, at his own expense carry out analyses in accordance with the measurement frequency and sample type specified for each determinand named below :-c
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Determinand i&m~:r-
For A : v/Total Residual Chlorine ~~I}i~
For Il : ~Suspended Solids ~ f.?- f2ll Ira
vO i I and Grease nlillm
VBlochemical Oxygen Demand (5 days. 200 C) ~{t:~~:ID (5x. 20· C)
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v iributyl Tins (TBT)
Unit Sam121 e' Type Wf& !:Ml7[25:\
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mg/L Grab ~R/ft- ~l\lfX mg/L Grab ~~/1l MIlX mg/L Grab ~}'i!:/1I- 'lJ1\1[X
mg/L Grab ~{{iY£nt- 1}1\1[X mg/L Crab ~1'1:!1t· :lJK1f.'l. mg:/L Grab ~YUfl- 'lJI\IlX mg/L Grab ~Yi:/11- :lJKlfX
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Fre<!!lency ff~
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Once during hull cleaning and washing event for every ship in dock other than sh i ps treated with non-TBT paints. m:{iJ-Fr.:i J.J.~ i\!i rr !l't} ~ WI ~ UW-lJXf]i-;): 0 ffrHVtl ~FTBT ~nhf~J!I1.~)'r 0
Grab sample shal I be taken during the period when the determinand to be analyzed for is I ikely to be present in its maximum concentration. Composite samples shal I be taken over dai Iy duration of the discharge. :/JK rfX. f~ * ~i1£ ~ J.E I&.:y:. n<j lIM.!!: [[f(J~:£:J& i% IY-J W j..~ m!f I m I"J :Ill! rt( 0 rft!, a .f~ * fl'HE fj R }MJl(JlIJ1 Al , {'F~til(frhllllX 0
Al I samples shal I be analyzed in accordance with the procedures set out in Annex 1 of the Technical Memorandum on Effluent Standards. m#.*_.~OOg*.~~.ft~.m~l~m~~~~f~~fio
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--./ 12.2 The licensee shal I retain and keep on the floating dock updated records of
all monitoring information, including all laboratory analytical results relating to samples taken, al I original chart recordings for continuous flow and pH monitoring for inspection by duly authorised officers of the Authority. Results of these monitoring shal I be summarized in-a report on a monthly basis and shal I be submittedta the Authority upon request.
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12.3 The licensee shal I notify and explain to the 'Authority immediately upon the occurrence of an accidental discharge or any emergency bypassing or overflow of untreated effluent or an operation upset which places the discharge in a temporary state af non-campi iance with this licence, and within seven days following the incident, submit to the Authority a detai led report on the cause and duration of the non-campI iance and 'steps ·taken or to be taken to reduce, el iminate, ·or prevent -recurrence of such non-campI iance. Reporting in accordance with this Condition does not rei ieve the I icensee of any obligations imposed by this licence.
{(~;£;jI,!\ #lHHJl:ttvK~Jill~I[(IZJfi!j7.l< , ~!~-r~tmW:!i~n.1~~MI- lilWk ('F-9d~ t ~ r 3i~Fl.&n<.Jf57.l< tl.\JJ;i.%i Jm ~r:'I'1{flll\!!\{l;\)1Je , f<!j IW A~tU:llIJ~i 1'@'F.'f:11IJ1iKl'bl'f-~ T ~'.1\!l\¥. 0 :tE:~I;j:iJC{/:iP:JH~ .1:::r;R F'I , ~~ffii*ili , ij:~mO~lfH!lQ;j • ~'1{ft1l.ft:A"JU~r.u , ttUICl.!iltl~€r:WJtl.{fllfffif~fil!i , .l:).ijJT .p,m~.m~~a.~~ffim.m~.~ •• ~o~w.~oo~.a~m~~.~ .ew~.~ft~.~~~A~.~~~.*~~~.~ •• o
12.4 The I icensee shall take all necessary measures to control and prevent the release of waste into the waters of Hong Kong. 'These shall include but shall not be I imited to good operational practices in hul I cleaning and painting as listed in Appendix A ..
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This Licence shal I be val id to _.~l August 1997 .
Licensee as referred to in this I iconce sha! I be the person who makes or authorizes the discharge; or the OWner or occupier of the said floating dock from which the discharge is made. KfJI!\!A:.lH~iJ~ftl:~*A , !i~~fi'/H'J~/tl:t;g*(lkJA f:/: , X)j~:fi':'J::)JJ1JlhJJUI~IM.:t:!J2{:I:P 0
For a licence granted under Section 15 of the Ordinance, the licensee of the said floating dock may apply under Section 19 of the Ordinance for a new I icence not less than 2 months before expiry of this I icence. The Authority may issue the licence or otherwise. . t:f*r1rHI1*t~{?]~fH"lC~Ji~lJiHI~h'l\!~(1n~#iJWA , CiJI~*Jj\\lOOJal~J.lUl'PJ~=ff&jJJ , $1:1** ,1~{9JmH ... :tL~:t:fI<JtJl.)1£ , $1iW-lfri~rJ~\!I~ 0 'lifHiUW~'bq.Nfl'«:It~(jlu~ruM1~~iHt{JlI1tlt« 0
Par a I icence granted under Section 16 or 20 of the Ordinance, the licensee of the said floating dock' may apply under Section 23A or 23 respectively of the Ordinance for a renewal of this licence not more than 4 months and not less than 2 months before the expiry of this I icence. The Authority may renew the licence or otherwise. . . r,,:rr:f~l/.j*~:t:~J~ +- 1\~1ixtfJ::.: -H'~~ifl! n{JJ:II!j~~(j<JNfM!A , uJl~*JlI\!ltWiil~fiu1'~ f~P.] {I/,l H :& 4' p I~ = {I:/d)j ~ , :flH1~ * t~ {9JJ m .:.: ··r ... ;::. t~ Lfl jl~m ::.: +:::-. jI-~ nkJ t5I. ~ , l~ ni1 WI ~Jl!\! ~t 0 'i!i' fWi;'1;:t'l-~fl'li1t~(jkr:J2lli*l!!JfJ!~JHfb:JW.ltH 0
Under Section 24 of the Ordinance, the Authority may by notice in writing impose new and amended termS and. conditions on this I icence or cancel this I icence. Under Section 25. 26 and 27 of the Ordinance, a I icensee whose I icence has been so varied or cancelled may be entitled to compensation. {rH~*~~f9l1m=-1-fL£l1~A~MUE , '8'flirr\lfti-ff-~~~TliHlJl~1 , Jf1JJfI~~iir*!\I\!I~trJgng~:t;~.&.m . 1ft! ,~l&m*ft!l!lm 0 :fltl1~p~#i{9JJtf!=+-1L, ':::+-j'\&,':::"1-t;1~A~j\Ji~ ,ral\!AAH(1'HjH~at~l& ~1 , ~Jl!\!A tiJfi~-erMjij.fill'm 0
Under Section 28 of the Ordinance, the licensee of the said floating dock may apply to the Authority to vary this licence. {N1J..lt4'~ f9um= .or .. /\1I.¥n~m5-i!: , NfJ;tlI.A [jJ r;;J'i:'i'~/lln)f,:iq.Ffl~I~]l?:-r&*)~q~ P:! rfri{~O~~~;tt 0
Under Section 49 of the Ordinance this licence shall not be construed as dispensation from the requirements of any other Ordinance except When that other Ordinance so provides. :fJ.Hl*Ms~]~ 12!l-I"'jd,;~(j~m)E , ~~r:!:i=J={cj;tt: {Ii! ~~H9U l!JJ:>O:lut , 'i!1 ~I!J~ {:pjl:l~!lt\HI~ kr:1'jt~ i~l;.;tf;?6 ~ ~f£MJ:l;jtl1~{~UJWW(IiU 0
In the event of discrepancies between the Engl ish text and the Chinese translations, the Engl ish shal I prevail. "{lnli!lrrJYfxri{*~m~WWf , HU~:iffXJl&:foi!\!l 0
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Appendix 2..
Good Operational Practices in Hull Cleaning & Painting
Every effort shall be made to intercept, contain and collect contaminants and to minim~se the release of such contaminants by implementing good operating practices. . .
When carrying out water washing on ship's hulls the pressure of water and the deployment and use of the water washing guns shall be monitored and adjusted to eliminate the unnecessary removal of paint film.
When carrying out high pressure water washing, scraping, mechanical descaling or gritblasting works on ships external hull surfaces, paint flakes and/or marine growth along with spent 'grit products will collect on the caisson deck of the floating do'cks and these solid waste residues shall be collected as good as possible and disposed of at regular intervals and in a suitable manner and in those cases when the wastes are produced from a ship's hull which is coated with a tin containing anti-fouling paint then whenever practicable those contaminated wastes shall be collected as good as possible prior to the next submergence of the floating docks.
A full inspection of the dock bottom has to be carried out to check the cleanliness prior to submerging the dock. particular attention shall be given to the removal of working waste, debris, rags, oil and 'paint spills, contaminated spent grit and marine growth.
All sink holes and water drains have to be closed during painting, cleansing and r; (sand) blasting.
When carrying out gritblasting works and when applying new paint coatings to ships' hulls then every effort shaH be made by the operator to minimise the unnecessary release of contaminants by exercising best practice as far as is practicable. In particular, attention should be given to operating the blasting and paint spray nozzles at the optimum distance from and angle to the hull surface being blasted or coated.
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Appendix A
The arnOl.mt of conslU11ables, i.e. paint, thinners and gritblasting slag, should be kept to the minimlU11 necessary to carry out the known works. Paint tins shall be opened only when necessary and used paint tins are to be emptied as far as possible before being collected in suitable receptacles which will be provided for this purpose and transported ashore for disposal. Unused paints shall be returned on board ship. When purging and cleaning of paint spray guns,. nozzles and hoses the resulting residue of paint and thitmer. and contaminated cleaning materials shall be collected in a suitable container and removed ashore for proper disposal and 110t sprayed on to the floor of the docks.
Adequate numbers of empty containers shall be provided on the docks for the purpose of collecting empty paint and thinner tins, spent grit, etc. and shall cnsure that full containers are removed from the docks in a regular and timely manner so that the contents can be disposed of in the best practice.
Any spillage of paint or thinner products on to the dock floor has to be cleaned immediately and the spillage has to be reported .
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WESTERN BUFFER WATER CONTROL ZONE
WATER QUALITY OBJECTIVES AND EFFLUENT
DISCHARGE REQUIREMENTS
ApPENDIX 3
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ApPENDIX "3 - WESTERN BUFFER WATER CONTROL ZONE - WATER
QUALITY OBJECTIVES AND EFFLUENT DISCHARGE LIMITS
Water Quality Objectives - Western Buffer Water Control Zone
A. Aesthetic Appearance
(a) There should be no objectionable odours or discolouration of the water. Whole Zone (b) Tarry residues, floating wood, articles made of glass, plastic, rubber or of Whole Zone
any other substances should be absent.
(c) Mineral oil should not be visible on the surface Whole Zone Surfactant should not give rise to a lasting foam.
(d) There should be no recognisable sewage-derived debris. Whole Zone
(e) Floating, submerged and semi-submerged Objects of a size likely to interfere with the free movement of vessels, or cause damage to vessels, should be
Whole Zone
absent.
(f) The water should not contain substances which settle to form objectionable deposits.
Whole Zone
B. Bacteria
(a) The level of Escherichia coli should not exceed 610 per 100 mI, calculated Secondary Contact as the geometric mean of all samples collected in a calendar year. Recreation Subzones
and Fish Culture Subzones
(b) The level of Escherichia coli should not exceed 180 per 100 mI, calculated Bathing Beach as the geometric mean of all samples collected from March to October Subzones inclusive in I calendar year. Samples should be taken at least 3 times in I calendar month at intervals of between 3 and 14 days.
(c) The level of Escherichia coli should be less than I per 100 mI, calculated as the geometric mean of the most recent 5 consecutive samples taken at
Water Gathering Ground Subzones
intervals of between 7 and 21 days,
(d) The level of Escherichia coli should not exceed 1000 per 100 mI, calculated as the geometric mean of the most recent 5 consecutive satnples taken at
Other inland waters
intervals of between 7 and 21 days.
C. Colour
(a) Human activity should not cause the colour of water to exceed 30 Hazen Water Gathering units. Ground Subzones
(b) Human activity should not cause the colour of water to exceed 590 Hazen Other inland waters umts.
D. Dissolved Oxygen
(a) The level of dissolved oxygen should not fall below 4 mg per litre for 90 % Marine waters of the sampling occasions during the whole year, values should be calculated excepting Fish as water column average (arithmetic mean of at least 3 measurements at I m Culture Subzones below surface, mid-depth and I m above seabed). In addition, the concentration of dissolved oxygen should not be less than 2 mg per litre within 2 m of the seabed for 90 % of the sampling occasions during the whole year.
(b) The level of dissolved oxygen should not be less than 5 mg per litre for 90% Fish Culture of the sampling occasions during the year, values should be calculated as Subzones water column average (arithmetic mean of at least 3 measurements at I m below surface mid-depth and 1 ma above seabed). In addition. the concentration of dissolved oxygen should not be less than 2 mg per litre within 2 m of the seabed for 90 % of the sampling occasions during the whole year.
(c) The level of dissolved oxygen should not be less than 4 mg per litre. Water Gathering Ground Subzones and other inland waters
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Water Quality Objectives - Western Buffer Water Control Zone (contd).
[
E. pH [
(a) The pf-i of the Water should be within the range of 6.5-8.5 units. In Marine Waters addition. human activity should not cause the natural pH range to be extended by more than 0.2 unit.
(b) Human activity should not cause the pH of the water to exceed the range of Water Gathering 6.5-8.5 units. Ground Subzones
(c) Human activity should not cause the pH of the water to exceed the range of Other Inland Waters 6.0-9.0 units. c
F. Temperature
Human activity should not cause the natural daily temperature range to Whole zone change by more than 2.0 C.
[ G. Salinity
Human activity should not cause the natural ambient salinity level to change Whole zone by more than 10%.
[ H. Suspended Solids
(a) Human activity should either cause the natural ambient level to be raised by Marine waters more than 30 % nor give rise to accumulation of suspended solids which may adversely affect aquatic communities.
c (b) Human activity should not cause the annual median of suspended solids to Water Gathering
exceed 20 mg per litre. Ground Subzones [ (c) Human activity should not cause the annual median of suspended solids to Other inland water
exceed 25 mg per litre.
I. Ammonla [ The un-ionized ammoniacal nitrogen level should not be more than 0.021 mg Whole zone per litre. calculated as the annual average (arithmetic mean).
J. Nutrients [ (a) Nutrients should not be present in quantities sufficient to cause excessive or Marine waters
nuisance growth of algae or other aquatic plants.
(b) Without limiting the generality of objective (a) above, the level of inorganic Marine waters nitrogen should not exceed 0.4 mg fer litre expressed as annual water column average (arithmetic mean a at least 3 measurements at I m below
[ surface, mid-depth and I m above seabed).
L. 5-Day Biochemical Oxygen Demand [ (a) The chemical oxygen demand should not exceed IS mg per litre. Water Gathering
Ground Subzones
(b) The chemical oxygen demand should not exceed 30 mg per litre Other inland waters [ M. Toxic substances (a) Toxic substances in the water should not attain such levels as to produce Whole zone
significant toxic, carcinogenic, mutagenic or teratogenic effects in humans, fish or any other aquatic or~anisms, with due regard to biologically cumulative effects in food cains and to interactions of toxic substances with
l each other.
(b) Human activity should not cause a risk to any beneficial use of the aquatic Whole zone environment. L
N. Turbidity
Waste discharges should not reduce light transmission substantially from the Bathing Beach normal level. Subzones
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Effluent Discharge Criteria - Western Buffer Water Control Zone
Flow rate slO >10 >200 >400 >600 > SIlo >1000 > 1500 >2000 >3000 >4000 (ml/day) "d ",d ",d >nd ",d 'nd ",d ",d ,nd ,nd
Detenninand ",200 s400 s600 SSOO slooo S; 1500 s2000 s3000 S4000 s5000
pH (pH units) 6-9 6-9 6-9 6-9 6-9 6-9 6-9 6-9 6-9 6-9 6-9
Temperarurc (0C) 40 40 40 40 40 40 40 40 40 40 40
Colour (lovibond 1 1 1 1 1 1 1 1 1 1 1 units) (25 nun cell length)
Suspended solids 50 30 30 30 30 30 30 30 30 30 30
BOD 50 20 20 20 20 20 20 20 20 20 20
COD 100 SO SO SO SO SO SO SO SO SO SO
Oil & Grease JO 20 20 20 20 20 20 20 20 20 20
Iron 15 10 10 7 5 • 3 2 1 1 O.S
Boron 5 • 3 2 2 1.5 1.1 O.S 0.5 0.4 O.J
Barium 5 • 3 2 2 1.5 l.i O.S 0.5 0.' 0.3
Mercury 0.1 0.001 0.001 O.lXH 0.001 0.001 0.001 0.001 0.001 0.001 0.001
Cadmium 0.1 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0,001 0.001 0.001 Other toxic metals 1 1 O.S 0.7 0.5 0.4 0.3 0.2 0.15 0.1 0.1
individually
Total toxic metals 2 2 1.6 1.4 1 O.S 0.6 0.' O.J 0.2 0.1
Cyanide 0.2 0.1 0.1 0.1 0.1 0.1 0.05 0.05 0.03 0.02 0.02
Phenols 0.5 0.5 0.5 0.3 0.25 0.2 0.1 0.1 0.1 0.1 0.1
Sulphide 5 5 5 5 5 5 2.5 2.5 1.5 1 1
Total residual 1 1 1 1 1 1 1 1 1 1 1 chlorine
Total nitrogen 100 100 SO SO SO SO 50 50 50 50 50
Total phosphorus 10 10 S S S 8 5 5 5 5 5 Surfactants (total) 20 15 15 15 15 15 10 10 10 10 10
E. coli ("C(iUntilOO ml)
1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000
Standards for effluents discharged into the inshore waters of the Western Buffer Water Control Zone
>5000 ,nd
s6000
6-9
40
1
30
20
SO
20
0.6
0.2
0.2
0.001
0.001
0.1
0.1
0.01
0.1
0.5
1
30
5
10
1000
(All units in mg/L unless otherwise stated; all figures are upper limits unless otherwise indicated)
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Figure 1 Hong Kong Water Control Zone as at 31 October 1994
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Eastern Duffer Water Control Zone
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LITERATURE REVIEW OF THE CHEMISTRY,
IMPACTS AND CONTROLS FOR TBTs
ApPENDIX 4
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Appendix 4, Final EIA Report, Reclamation and Relocation o/United Dock 10 Tsing Yi Hong Kong United Dockyards
APPENDIX 4 CHEMISTRY AND IMPACT OF TRIBUTYL TINS
1
2
INTRODUCTION
A literature review of research into the chemistry and environmental impact of TBTs was undertaken. Also, legislative limits and operational constraints which have been enforced in other parts of the world were investigated. Previous investigations into TBT contamination in other parts of Hong Kong were also reviewed. This study was undertaken to provide a thorough understanding of TBTs on which a prediction of the impact ofTBTs released from United could be based.
TBT containing paints were developed in the mid 1960s for use as an antifoulant or biocide on ships. These paints provide effective long term protection to ships' surfaces from marine growth, such as barnacles algae, tubeworms, hydro ids and sponges, and are therefore favoured by ship owners due to the savings that can be achieved through their use. Marine growth can reduce the speed of ships in the water, therefore, the use of an effective biocide such as TBTs can result in annual savings in fossil fuels by reducing the frictional effects of biofouling by up to fifteen percent.' TBT treated ships require less maintenance since TBTs do not promote corrosion unlike other antifoulants.' Due to the effectiveness of TBTs the paint only requires replacing every five - seven years unlike conventional copper oxide antifoulants which last only two years?
SOURCES OF TBTS IN THE MARINE ENVmONMENT
TBT containing paints have been widely used on commercial and pleasure boats over the last three decades, and as a result have caused significant levels of this man-made compound to accumulate in the marine environment. In many parts of the world it has been found that concentrations of TBTs have become high in sea water, particularly in sheltered marinas and harbours where boat use is intensive. Adverse environmental impacts have occurred where TBTs levels are elevated; in particular, population declines and deformities in non-target organisms""'" and these are discussed in more detail below.
TBTs can enter the marine environment from several sources, those relevant to this project are briefly outlined below:
• Cleaning of ships hulls using higb pressure water wash down can remove as much as 60mg TBT cm-' of hull surface'. Research into typical loads ofTBTs entering the marine environment from washing down before repainting, found loads to be greatest from yachts rather than ships, possibly due to the formulations used on yachts being softer than those employed on larger vessels. The TBT concentration in waste water from the dry dock was about 40 mg/l ' for "free association" paints and an order of magnitude higher for copolymer paints (depending on the age ofthe paint layer as free association paints release most of their TBTs more rapidly than copolymer paints).
• Sand or grit (utility slag or copper slag) blasting are common methods of surface preparation in commercial yards because of their removal speed and costs. When employed, the spent abrasive, including old paint, is collected by manual means and disposed of as a controlled waste. Particle sizes of the used grit range from fme dustto approximately one-eighth inch in diameter.
/92000/app4.dac Axis Environmental Consultants Ltd.
Appendix 4. Final EIA Report, Reclamation and Relocation o/United Dock to Tsing Yi Hong Kong United Dockyards
3
Some of this grit can also fall directly into drainage gutters and, together with material that is not swept up and disposed of, may be washed into the dock's drainage system by storm water or shipboard waste water and therefore be present in the dry dock discharge. The potential also exists for the fme particles of abrasive to be blown away. The requirement for abrasive blasting can be avoided through the use of self polishing paints which can be applied directly to the hull following water cleaning. As these paints do not require the underlying layers of antifoulants paint to be removed, the overall loss of TBT to the environment can be reduced. Typical levels, quoted in the literature as being released in hull run off, are about I mg/1. '
• Painting takes place in commercial yards after water cleaning andlor blasting. The paint is sprayed onto the ship's surface and therefore has the potential to drift into surface water. According to the literature, paint drift occurs to a greater extent in floating docks than in slipways and drydocks, and when applied airless in open air, the emission of paint by drift is 2 - 20%: The literature quotes a typical level ofTBTs in the hull runoff during this process of about 10 fig/I'. Several factors help to reduce emissions ofTBTs from paint application: I. the sophisticated painting equipment encourages skill specialisation and training in
the safe and efficient use of equipment, minimising paint losses to the environment; 2. restricting the use ofTBT paints to commercial ship yards only; and 3. the high cost of the paint which discourages waste'.
• Waste material present on the floor of the dock can enter the aquatic environment. Paint scrapings, blasting grit, paint splashes and paint left in containers, on brushes and rags are all potential sources ofTBTs to the aquatic environment.
Appendix 3 details the results from recent studies undertaken to quantify inputs of TBTs to the aquatic environment from wash down and paint application.
THE CHEMISTRY OF TBTs
Organotins, of which TBT is the most toxic compound, are formed by the attachment of alkyl or aryl groups to the tin atom by a covalent bond. There is no evidence that TBT is a naturally produced compound in any measurable quantity and the presence of TBTs in marine sediments and waters is almost entirely attributable to the use of antifoulant paints. Antifoulant paints contain the tributyl tin oxide (TBTO) form ofTBT.
When antifoulant paints containing TBTs were first devised, the TBTs were physically dispersed in a hard insoluble matrix, often referred to as "free association" paints. As the TBTs leach out of these paints, pores are left behind through which the seawater can percolate encouraging further dissolution and release of the biocide. Eventually the pores become clogged with insoluble compounds such as calcium carbonate inhibiting the effects of the biocide. All conventional TBT paints containing free associated TBTs release the TBTs exponentially, beginning with a high release rate and are effective for an average of three - five years.7
Release of TBTs from paints can be reduced through the use of paints where the TBT is bound into a copolymer "backbone" as opposed to using the original "free association" TBT paints. Self Polishing Copolymer (SPC) paints are widely used in preference to free association paints as they do not have to be removed from the hull of a ship before repainting. All ships repaired and cleaned by HUD requiring TBT paints use SPC paints which are effective for up to seven years? HUD only grit blasts TBT paints from the hull of a ship when rusty areas of the hull need painting or when paints other than SPCs have been used previously.
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The action of the seawater on the copolymer paint film causes hydrolysis of the organotin linkage. These freely associated groups then help to erode the paint and expose a fresh surface of the TBT containing paint. Since the TBT release rate is governed by the hydrolysis of the TBT group, the release of TBTs can be more effectively controlled than in free association paints, where release is governed by the rate of diffusion. Leach rates into the marine environment from copolymer paints fall between 6 - II !!g1cm' /day.'
At equilibrium, TBTs dissolved in seawater form a mixture of compounds; tributyl tin chloride, tributyl tin carbonates, tributyltin hydroxide and the aqua complex
(TBTOH;). The relative contribution of these species depend on the total salt content of the water, the dissolved carbon dioxide and the hydrogen ion concentration. The distribution of these compounds also partly determines the bioaccumulation of TBTs by marine organisms.3 The lilJOphilic nature of TBTs allows them to accumulate in the tissues of marine organisms.8
The persistence of TBTs in the marine environment is poorly known but the literature quotes a half life of between one and three years, however this can be significantly longer when the TBTs are bound with anaerobic sediments: Degradation of TBTO involves the splitting of the carbon-tin bond. It is thought that photolysis (breakdown by sunlight) may be an important mode of abiotic degradation of the TBT to dibutyl and monobutyl tin ions which are considered to be relatively harmless compared to TBT itself.'
Once in the marine environment the TBT compound may be adsorbed onto particulates and removed from the aqueous environment through sedimentation. Between 10% and 95% of TBTO introduced into the water is estimated to undergo particulate adsorption.8
Sediment analysis often reveals a non-uniform distribution of TBTs due to the quick association of the TBT compounds with the sediment. In this form in the sediment the TBT remains readily available to marine organisms, especially those in the benthos. Progressive disappearance of adsorbed TBT from the sediment is largely due to biotic and/or abiotic degradation and not due to desorption into the seawater. Microorganisms, for example, can limit the persistence of TBTs (through biodegradation into monobutyl tins) to 162 and 815 days for aerobic and anaerobic sediments respectively? TBTs which enter the marine environment as part of a paint chip have been quoted as being not readily available to organisms and therefore would be less likely to have an impact on the benthos?
IMPACTS OF TBTs ON THE MARINE ENVIRONMENT
TBT has become a problem in the marine environment due to its impact on non-target organisms. Research has shown that many marine organisms are killed by continuous exposure to levels in waters containing less than one part per billion of the substance. TBTs have been implicated in fish kills, lobster mortalities and the disappearance of many indigenous organisms from the harbours of the world?
Early research into the toxicity of TBTs tended to concentrate on the effect of short term exposures of high concentrations of TBTs on organisms. These studies are not particularly environmentally relevant as they did not consider the role of bioaccumulation and metabolism when determining the toxic effects of TBTs.
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Appendix 4. Final EIA Report. Reclamation and Relocation of United Dock to Tsing Yi Hong Kong United Dockyards
Bioaccumulation occurs where TBTs taken from the environment are concentrated into the tissues of non-target organisms by factors from 1,000 to over 10,000. This is a result of TBT"s high solubility in fat. For example, in the Pacific oyster (Crassostrea gigas) TBT tissue concentrations have been found to be in the region of up to 30,000 times higher than the environmental concentration of TBTs. Molluscs tend to have high bioaccumulation rates since they process relatively large amounts of water when feeding. There is, however, no indication that TBT is transferred to terrestrial organisms via the food chains.
More recently, in many countries of the world, particularly in the northern hemisphere where there has been more extensive use of TBTs, correlations between exposure to TBTs from antifouling paints and population decreases in commercial fisheries have been identified. Two examples are given below:
• Poor tidal flushing in the French Bay, Baie d' Arcachon, which had had a flourishing oyster industry in the early 1970s, allowed TBTs released from antifoulant paints on pleasure crafts to accumulate. Malformation and thickening of oyster shells, the reduction or absence of spat fall (the development of young bivalves through larval settlement) and the death of 50% of healthy oysters transplanted into the area resulted from the accumulation of TBTs.'
• Between 1982 and 1984, the UK Ministry of Agriculture, Fisheries and Foods (MAFF) undertook extensive laboratory and field trials which confirmed that some UK estuaries contained sufficient organotin compounds, up to 2,200 ng TBTIl, to cause reduced meat yields and shell thickening in the Pacific oyster and the economically important European flat oyster, Ostrea edulis. The disruption of growth was found to occur at 250 n~ TBT/I in O. edulis and 160 ng TBT/I in C. gigas, or an average of200 ng! TBT/I.
The effect of TBTs on marine organisms has been studied in order that a safe limit for TBTs can be found. Fish, bivalves, gastropods and crustaceans exposed to low concentrations of organotins, can show many symptoms before death occurs. Accumulation of relatively low background concentrations of TBTs in tissues can result in a loss of appetite, organ and tissue changes, reduction in reproductive capacity, decreased growth, poor co-ordination, loss of mobility, changes in enzymatic pathways, shell deformations and inhibition of development of newly laid eggs.7 Overseas studies, laboratory testing and field experiments have established TBT to be toxic at the following low, sublethal levels to:
• Fish at 200 ng TBT/l; • Bivalves at 50 ng TBT/I; • Gastropods at 20 ng TBT/I; and • Crustaceans at 250 ng TBT/I. It is also of note that in North America, on the basis of preliminary observations it was found that where TBT levels are greater than 100 ng TBT/I in marinas, the native organisms had disappeared.'
A safe level for TBTs in marine waters has been difficult to determine due to the different responses of organisms to TBT in terms of bioaccumulation and effect. The most sensitive marine organism to TBTs (so far identified) is the mysid shrimp whose larvae are disturbed by acute exposures of 0.5 /lg!l in seawater. Chronic toxicities have
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not yet been determined in the shrimp but a safe level for TBTs is estimated to be at least a factor often below the acute toxicity level, that is, 0.05 1lg/1?
The impact of TBTs in the sediment has not been widely investigated, therefore the determination of a safe level for TBT in marine sediments poses further problems. One study attempted to investigate the impact on benthic dwelling organisms. Abraded paint waS used to produce the material most likely to normally contaminate sediments. Sediment samples containing 0.1, I, 10 and 100 mg TBT/kg were prepared and placed in excavated trenches. Recolonisation could then take place through the settlement of organisms from above and through lateral transfer of organisms from adjoining mud. Surface sediment was found to decontaminate rapidly as a result of water movement and deposition of new sediment whereas the subsurface TBT levels remained reasonably stable. Burrowing activity of the polychaete worms, Arenieo/a marina was reduced at all concentrations of TBT, although the effect of O.lmg TBT/kg disappeared over the first three months. A dose related effect in populations of the burrowing polychaete Se%p/os armiger and the burrowing amphipod Urothoe poseidonis was observed over the concentration range. Generally it was noted that surface dwelling organisms, such as the cockle, which filter feed from the overlying sea water rather than feeding on particles in the sediment, were less effected than species dwelling in the bottom layers, such as U poseidon is.'
LEGISLATIVE CONTROLS ON TBTs
General Legislation to Control TBTs
The potential disruption of valuable fisheries and communities of organisms in coastal areas has led to the development of some regulation controlling the use of TBT in antifouling paint. Several strategies have been employed throughout the world to reduce TBTs in water. These include the regulation of paint composition and prohibiting their use on small boats, which tend to congregate in enclosed waters such as marinas. Some countries of the world, such as Germany and Switzerland, have prohibited the use of any organotin compounds in antifouling paints7
•
In the UK and France, TBTs were regulated in the aftermath of the events described in section 3.4 above. In 1982, as a result of the findings at Arcachon Bay, the French Government banned the use ofTBT-containing paints on all pleasure craft less than 25m in length. This measure has since been widely adopted and also applies in Hong Kong.
In the UK, the average TBT concentration found by MAFF to cause the disruption of growth in oysters, was used to set target limits for marine water quality. A safety factor of 10, which takes into account the extrapolation of these acute data to the chronic situation, reduces the value to 20 ng/I. This concentration was adopted by the UK as a target value for marine waters in 1985 with an improved target of 2 ng/l for 19893
; this level has since been adopted by Canada and Australia.7
TBT copolymer paints with more than 7.5% TBT, and other paints with copper or other antifouling agents with more than 2.5% TBT have been banned since 1986 in the UK on all vessels under 25m (which has effectively prohibited the use of free-association paints). In May 1987 in the UK, under the Control of Pollution (Antifouling Paints and Treatments) Regulations 1987, the retail and supply for retail sale of antifouling paints
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Appendix 4, Final EIA Report, Reclamation and Relocation of United Dock to Tsing Yi Hong Kong United Dockyards
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containing a triorganotin compound was prohibited for ships smaller than 25m. Under the UK's Food and Environment Protection Act 1985, all surface treatments and antifouling paints applied to yachts and larger vessels are subject to the pesticide approval scheme. A similar situation has been introduced to Hong Kong whereby all users of TBTs are registered by tbe Agriculture and Fisheries Department (AFD) under the Pesticides Ordinance, Cap 133.
In Australia, particularly in New South Wales, six different pieces of legislation provide the framework for control needed to regulate the use of organotins. Most relevant to this study is the Clean Waters Act, 1970. This Act is designed to control water pollution and requires any person wishing to discharge waste to obtain a license. Through this legislation washdowns from slipways can be controlled as the discharge may contain organotins in the form of soluble paint residues, paint chips and dust resulting from shipyard equipment and procedures. Complementary controls are, however, required to cover disposal and collection of wastes on slipways.
Chemical Control Orders (CCO), gazetted under the Environmentally Hazardous Chemicals Act, 1989 in New South Wales are currently being revised with respect to controlling TBT wastes. The likely concentrations which will define wastes that will be subject to the new CCO are:
• Solid Wastes containing over 0.004 mg/kg.
• Liquid wastes containing over a yet to be determined value, probably in the range of 2-50 ng/l.
However it is unlikely that this CCO can be applied for large ship cleaning since it would not be practical to collect such large volumes of water for treatment prior to discharge (up to 500 tonnes of water). The Hong Kong Water Pollution Control Ordinance (WPCO), Cap.358, is similar to this in that a license is required to discharge into tbe Water Control Zones (WCZ) of Hong Kong. The WPCO does not currently set limits for TBTs in tbe effluents or receiving waters but it does prohibit tbe release of all toxic substances into the WCZ, which effectively bans the release of TBTs .
TBT Legislation with Regard to Floating Docks and Commercial Shipyards
Floating Docks are found in otber areas of tbe world. In Australia for example a floating dock is moored off Newcastle, New South Wales and the Royal Australian Navy operates a floating dock in Sydney. NSW EPA have attempted to get floating docks to comply with pollution control requirements since 1993. The achievements to date have been a result of general housekeeping, control of atmospheric emissions and solid waste disposal. Little has been achieved regarding the control of waste water. Controls are applied to a certain extent to minimize paint flakes and particulates entering the marine environment through the use of sandbags to· filter particulates and impede discharge allowing particulates to settle out and then be collected. One of the dock's licenses contains a requirement to investigate the TBT contamination in waters and sediments, monitor TBT in washwater discharged during hull blasting as well as numerous conditions relating to housekeeping.
It should be noted that none of the floating docks investigated were found to be located off shore and cases are considered on a site specific basis. All requirements for discharge
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control have been given a phasing in period to enable feasible solutions, both economically and practically to be found and implemented.
In the UK, the Royal Yachting Association in conjunction with the UK DoE and other bodies in the UK have produced a leafiet lO referring to the safe disposal of TBT paint removed from ships and boats in an attempt to reduce TBT pollution from old paint. However, this booklet does not consider floating docks.
In the European Union (EU) a draft Directive, "Biocidal Products Directive", COM (93) 351, is currently under review which could completely ban the application of TBT paints· in the EU from 1997. This is currently arousing great concern amongst dock operators in Europe as the possible ban on application of TBT paints will in all likelihood merely result in ship operators going elsewhere to dry dock.
EPD's STUDY OF TBT CONTAMINATION IN HONG KONG SEDIMENTS
EPD commissioned a study of the extent of TBT contamination in the sediments of Hong Kong's shipyards and marinas!!. Sediment samples were taken from shipyards along a transect to demonstrate the concentration variation with distance, and randomly from the sediments of marinas. Hypotheses were formulated and tested for statistical validity.
The results indicated that sediments in the shipyards and marinas of Hong Kong were highly contaminated with TBTs. The average concentration of TBTs found in the sediments are given in Table!. Analysis of subsamples produced greatly differing results indicating that TBT pollution is very localized depending on the presence of a paint chip or a particulate which has associated with a TBT ion. The highest concentration measured was 137,800 ng TBT/g dry weight which was found at Causeway Bay Marina and Typhoon Shelter.
Having statistically tested the hypotheses formulated at the outset of the study the following was found:
• Levels of sediment associated TBT are significantly elevated in the vicinity of the local marina. Found to be valid from the results.
• Levels of sediment toxicity are significantly elevated in the vicinity of the local marina. Not valid from the data set obtained.
• Levels of sediment associated TBT are significantly elevated in the vicinity of shipyards. Valid for all shipyards except for one site at Tsing Yi North where dock operations only commenced recently.
• Levels of sediment toxicity are significantly elevated in the vicinity of shipyards. This was valid for Tai Po and one of the sites studied at Tsing Yi South and Tsing Yi North.
• The TBT concentration at 50m distance from the shipyard is elevated above the background concentration. This was only valid at Tai Po and one site at Tsing Yi South.
• There is a significant correlation between the levels ofTBT contamination and toxicity of the sediments. Found to be valid.
• TBT levels in sediment near shipyards were significantly differentfrom that near marinas. Not valid.
• Shipyards that mostly handle larger(> 25m) boats show significantly higher TBT level than shipyards that mostly handle smaller «25m) boats. Not valid.
•
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Overall it was concluded that high TBT concentrations were found in the sediments taken from the shipyards and marinas of Hong Kong. Shipyards were found to be as contaminated as marinas and so it was not possible to demonstrate which was the more significant source of TBTs - paint removal operations or leaching into the seawater. Despite a ban on the use of paints containing TBTs on boats under 25m in Hong Kong, shipyards that handle boats over 25m did not have significantly greater concentrations of TBTs in sediments than those mostly handling boats under 25m. A correlation was found between TBT concentrations in the sediment and the toxicity of the sediment to microorganisms, although the sediment toxicity results for marinas are conflicting. Finally, it was found that sediments taken from new shipyards had significantly lower TBT concentrations than those from older sites.
Comparison of TBT Levels in Hong Kong Sediments to those found in Other Countries.
The results can be compared to sediment concentrations found in other areas of the world. A review of the literature has revealed that maximum levels found elsewhere are less than or equivalent to average levels found in EPD's study. In New Zealand the highest values were found to be 240 and 150 ng TBT-Sn /g in the Tamaki estuary; 240 ng TBT-Sn /g in Toronto Harbour and as much as 10,800ng TBT-Sn/g in Vancouver Harbour; 12 - 44 ng TBT-Snlg in New Hampshire and 41 ng TBT-Snlg in Osaka, Japan.l2 Most of the average values found in Hong Kong sediments were similar but levels found at Aberdeen Boat Club, Aberdeen Shipyards and Tsing Yi North were an order of magnitude above these values. TBT concentrations found at Causeway Bay Marina were two orders of magnitude above maximum levels found in other parts of the world.
The impact ofTBTs in sediments has not been widely studied and as a result the fate and its bioavailability to marine organisms is not fully understood. One study did however find levels above 100 ng TBT/g to be harmful to polychaete worms which feed on fine particles in the sediment. The effect of TBTs on the populations of other burrowing organisms was found to be proportional to TBT concentration.' Contaminated sediments are also thought to cause an impact if remobilised by storms, currents and dredging of marinas, mooring areas and shipping channels.
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Table 1 Mean TBT Concentrations Found in Sediments Around Hong Kong
SITE MEANTBT MEANTBT CONCENTRATION CONCENTRATION
(ng Sn/g) (ngTBT/g)
Causeway Bay Marina 11,618.0 30,206.8
Marina Cove 507.0 1,318.2
Hebe Haven marina 598.0 1,554.8
Aberdeen Boat Club 3,468.0 9,016.8
Gold Coast Marina 6.0 15.6
Pak Sha Wan Shipyards 747.0 1,942.2
Sai Kung. 349.0 907.4
Tsing Yi North 1 35.0 91
Tsing Yi North 2 1,970.0 20,722
Tsing Yi South I 319.0 829.4
Tsing Yi South 2 372.0 967.2
TaiPo 190.0 494
Aberdeen South 1,153.0 2,997.8
Aberdeen 2 Typhoon Shelter 181.0 470.6
Control 17.2 44.7
SUMMARY
The literature review has clearly indicated the extent of the problem that has arisen through the use of TBTs in marine paints. TBT is the most effective antifouling agent found to date and as a result can save ship owners money on maintenance costs, increase ship speed and reduce fuel costs. As a result it has been widely used over the last three decades.
Non target marine organisms have been found to be effected by very low concentrations of TBTs in sea water. The most sensitive marine organism to TBTs so far recorded is the mysid shrimp whose larvae are disturbed by acute exposures of 0.5 flgll TBT in seawater. Chronic toxicities have not yet been determined in the shrimp but a safe level for TBTs is estimated to be at least a factor of ten below the acute toxicity level, that is, 0.05 flgfl.
Marine sediments act as a sink for TBTs and levels in sediments greatly exceed concentrations found in overlying waters. Accumulation in sediments occurs through adsorption of dissolved TBTs to particulates and through the settlement of paint chips. The availability of TBTs in sediments is not clearly understood and is site specific depending on, amongst other things, organisms present and their sensitivity. One study
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Appendix 4, Final EIA Report, Reclamation and Relocation of United Dock to Tsing Yi Hong Kong United Dockyards
has however demonstrated sediment levels of 100ng TBT/g to cause a reduction in populations of mud dwelling organisms.
Legislation now exists to limit the use of TBTs and guideline values have been adopted in certain areas for marine waters. These values range between 5 - 20 ng/l. World wide the release of TBTs from floating docks has not been addressed in terms of legislation and the setting of achievable goals. Hong Kong legislation currently prohibits the release of TBTs into Water Control Zones although this has not yet been enforced on floating docks and would not be practical to do so.
Sediment concentrations of TBTs around marinas and shipyards in Hong Kong are elevated when compared to background levels and concentrations found in the harbours of other countries. Levels found in marinas were not found to be declining when compared to EPDs last study in 1989, as is the case elsewhere in the world, despite the ban on the use of TBTs on pleasure boats.
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ApPENDIX 5
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Hongkong United Dockyards Ltd - Extension to TITL J08RP Proposed reclamation and relocation of United Float;ng Dock Environmental Impact Assessment- Final Report
APPENDIX 5 HUD SHIPYARD PLUME STUDIES
1 INTRODUCTION
2
2.1
In April 1996 Hydraulics and Water Research (Asia) Ltd were commissioned by Axis Environmental on behalf of HUD to investigate the fate of material lost to suspension from HUD's floating drydock.
The aim of the study was to determine the impacts caused by the transport of material from the existing site in Yam 0 Wan and from the proposed site in Tsing Yi and hence determine whether the relocation of the dock would result in any improvements in water quality. The W AHMO sediment plume model has been used to model the loss of material to suspension and its subsequent transport and dispersion by tidal currents.
The model results for the Tsing Yi scenario provide information on the dispersion of pollutants such as suspended solids, metals (notably copper and zinc) and Tributyl tin from the wash water discharge. They also provide an indication of the fate of sediment disturbed and released during the proposed dredging and reclamation works at Tsing Yi should the project proceed.
METHODOLOGY
Tidal Flow Modelling
Two tidal flow models have been used to provide flow data for the sediment plume simulations.
The flow data for Scenario I was provided by the extended W AHMO 250m grid flow model. The model covers all of Hong Kong waters, the Pearl Estuary, the area to the south of Hong Kong up to the Lema Channel and east to Mirs Bay. The model included the current reclamations for the North Lantau Expressway, Chep Lap Kok, West Kowloon, Container Terminal 7 and 8, Central Phase I and HKCEC.
The flow data for Scenarios 2 and 3 were provided by the W AHMO 50m grid model which had previously been set up to investigate the impact of the Ting Kau Bridge on tidal flows. The model covers the whole of the Rambler Channel and extends west to beyond Ma Wan and south to the tip of Tsing Yi. The model originally included reclamations for the Ting Kau Bridge and Container Terminals 7, 8 and 9. For this project the model was re-run to include reclamations for the Kap Shui Mun and Tsing Ma bridge piers and for the HUD facility on the western shore of Tsing Yi island adjacent to their existing facility. Results from the re-run of the flow model have been presented as vector plots for peak ebb and flood phases of the tidal cycle for both the upper and lower layers of the model.
The dry season spring tide was used in the model as this tide has the largest tidal excursion and therefore represents the tide over which the discharges from the dock could have the greatest area of impact. In order to demonstrate this HWR modelled the release of floats on both the ebb and flood phases of the tidal cycle from both the existing site and proposed site at Tsing Yi. The float tracks demonstrate that the float is carried further by the dry season spring tide.
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2.2
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4.1
Sediment Plume Simulations
Models were run for three tidal cycles each 24.5 hours in length and particle deposition rates were calculated for the material released per tidal cycle. Three scenarios have been simulated using the WAHMO sediment plume model.
Scenario 1 simulated losses of material from the existing location of the HUD floating dry dock at the entrance to Yam 0 Wan. Material was i~ected into the surface layer of the model at three points which were evenly spaced along the length of the dock. The total rate of i~ection was simulated as being I kg/so For these simulations it was assumed that the material behaved in the same way as suspended sediment particles in that it would be transported by tidal currents and settle onto the seabed. However, once the material settled onto the seabed it was assumed that it would not be re-eroded by tidal currents.
Scenario 2 simulated the loss of material from the proposed location of the dock at the new facility on the western shore of Tsing Yi. The method of simulation was the same as for Scenario I.
Scenario 3 also simulated the loss of material from the proposed location of the dock at the new facility on the western shore of Tsing Yi. For this scenario material was injected into the model at a single point close to the shoreline and approximately 100m to the east of the proposed location of the dry dock. As before, the rate of injection was simulated as being lkg/s.
RESULTS
The results from the sediment plume simulations have been presented as contour plots of suspended material concentrations on both ebb and flood phases of the tide and as contour plots of deposition rates. It should be noted that in both Scenarios 2 and 3, the plumes from the proposed dry dock location on the western shore of Tsing Yi reach the boundaries of the model. The eight attached plots illustrate the plume study results.
DISCUSSION
Interpretation of model runs
Interpretation of the results is based on the assumption that the most significant source of TBT discharge from the dock to the marine environment is in the form of paint chips removed during the blasting and wash down of a ship's hull. Since most antifoulant material is designed to be slow-release due to the need to prolong the intervals between docking, it is assumed that TBT will not rapidly dissolve and will therefore remain within the paint chip for the period between removal and discharge into the sea. The same is true for copper and zinc which are also used in antifoulants. Copper may also be entering the environment in the form of particulates from the copper slag used to blast the hull to remove marine growth and rust. The pollutants of concern have similar characteristics, therefore in that they are most likely to be entering the marine environment in particulate form. The following provides a qualitative description of where the pollutants would accumulate and particle deposition rates would be greatest.
Scenario 1 - United in its current location, Yam 0 Wan.
For the modelled dry season spring tide, discharge during the ebb tide from the dock would disperse over an area extending along the north Lantau coast and would then be taken with the tide through the Kap Shui Mun channel south towards Peng Chau. The main
Axis Environmental Consultants Ltd AXV1 51 3//92-000 Page 53
Hongkong United Dockyards Ltd - Extension to TYTL l08RP Proposed reclamation and relocation of United Floating Dock Environmental Impact Assessment - Final Report
concentration of pollutants in the water during the washdown process would however be in the immediate vicinity of the dock. During the flood tide, pollutants would be dispersed along the North Lantau coast with a peak concentration close to the point of discharge.
The model indicates that particle deposition is concentrated in a linear pattern along the North Lantau coast to a point south of the Brothers. There is also a small area past the Kap Shui Mun channel where relatively high concentrations, carried 'by the ebb tide, may be accumulating. To a lesser degree, sedimentation is occurring around the Brothers and on the other side of Lantau as far south as the area between Peng Chau and Chau Kung To. Sedimentation of the particulate material released from the dock is also occurring to a minimal extent around the coast ofMa Wan. The plume was digitised in order to determine the total area of potential impact, as shown by the model, and was found to be 15.66 sq km. The maximum deposition rates occur over a much smaller area, 0.38 sq km.
Scenario 2 - Dock in Proposed Location, Tsing Yi with no controls
Should the dock be relocated to Tsing Yi Island and the small scale reclamation take place then it is apparent that peak concentrations of pollutants in the water column would occur in a northerly direction along the western coast of Tsing Yi and into the waters off the coast between Sham Tseng and Ting Kau. Lower concentrations would spread in a westerly direction with the majority of pollutants occurring at least SOOm from the coastline. The modelled ebb tide scenario indicates that pollutants would be dispersed largely in a linear pattern to the south closely following the western coastline of Tsing Vi.
Particle deposition under Scenario 2 would indicate that the material would be dispersed relatively evenly within a 1 km band which follows the western coast of Tsing Yi around to and along the coast of the south west New Territories probably as far as Brother Point though this is difficult to determine given the boundaries of the model used. Generally there would only be a small area where sedimentation was concentrated and that would be in the bay to the south of the proposed reclamation. Compared to Scenario 1, pollutants would be more evenly dispersed than in the current situation and generally the sediments in the immediate vicinity of the dock would not contain such high concentrations of contaminants. This is probably due to greater current velocities in Tsing Yi diluting and dispersing the contaminants. The total area of potential impact was again calculated by digitising the plume and was found to cover an area of 4.06 sq km but was also noted to spread beyond the boundary of the model. The maximum deposition occurred over 0.01 sq km, less than that measured under Scenario I.
Scenario 3 - Dock in proposed location at Tsing Yi - controlled discharge
Under Scenario 3 it is assumed that a method is employed on the dock to divert the washwater so that it is discharged from one point on the dock into the small bay rather than into the faster flowing water in the Ma Wan Fairway. As a result, during the flood tide, pollutant concentrations would be much greater along the north west coast of Tsing Vi, around the proposed site and to the immediate north of the site. Similar pollutant concentrations to Scenario 1 would occur in the waters off the southern coast of the western New Territories. During the ebb tide there would be a very high concentration of pollutants in the water immediately south east of (he discharge and a plume of contaminants, in lower concentrations, dispersing in a southerly direction along the western coast of Tsing Vi. The band of pollutants in the water column would be narrower than in Scenario 2.
In terms of particle deposition, high concentrations of contaminants would accumulate in a narrow band «SOOm) extending approximately 3km north of the site and 2 km south of the
Axis ·Environmental Consultants Ltd AXV15131192·000
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site. Total area of potential impact was measured as 3.41 sq km, less than the previous two scenarios and the peak deposition although greater than scenario 2 was less than scenario I i.e. 0.22 sq km.
4.2 Potential Concentrations of Contaminants
Since there is very little data on actual particle size of TBT containing material, patterns or volumes of material released during the discharge it is difficult to make any accurate quantitative evaluation of the release ofTBTs in the washwater. The following provide best estimates based on available information and should only be taken as an indication of the potential impact.
In the Initial Assessment Report for the mooring of United in Yam 0 Wan (Axis, 1994) it was calculated that the area of dock likely to be painted with an antifoulant is 6000 sq m. Therefore the quantity of antifoulant likely to be removed from the dock during water blasting is 6kg. The most commercially available antifoulant applications contain less than 30% TBTM copolymer and the maximum concentration of TBTO, the biologically available Tributyl tin component is 1-5% by weight. The quantity of available TBT removed during each washdown period is 60-300 grams per ship. Each water blasting operation involves the use of up to 500 tonnes of water so the potential active TBT in the waste water discharge could be in the order of 0.1-0.6 mg/I (100-600 Ilg/I).
The effectiveness of the housekeeping measures in terms of trapping paint in cloth filters placed over the drainage ports is difficult to quantify but should be considered so as not to over estimate the extent of the impact. The literature indicates that the housekeeping measures such as those now used on United can reduce TBT emissions by up to 40% (Haskoning, 1989, Study for the European Commission). Measurements of TBT in process water taken hourly over two wash down periods prior to discharge on United have averaged at 641 1lg/1 with a maximum of 1.6 mg/1. These figures represent actual TBT lost to the marine environment and therefore does not include the amount of TBT in paint flakes trapped on the deck of the dock. To a certain extent therefore this figure includes a consideration of housekeeping measures except for the mitigating effect of placing cloth filters over the drainage ports. This figure also indicates that the original calculation of TBT lost to the marine environment was slightly low. It is not known how much paint is trapped by the cloth filters on the drainage ports, but the average concentration of TBT in the washwater just before it enters the drainage ports has been used in the following calculations as a good indication of the TBT released to the marine environment in the washwater. The average is also in fairly close agreement with the range of TBT originally calculated to be lost during a washdown period.
If 300 grams are released over the washdown period then this would be equivalent to a loss of 0.0052 grams per second or 5.2 mg/s assuming that washdown occurs over two working days.
The model looked at a release of Ikg of particulate material per second. A maximum of 4mg/l was recorded in the water column under this scenario. Therefore if 5.2mg/s of TBT were released then 0.00002Img/1 would be the maximum TBT concentration in the water column in the form of particulates. This is equivalent to 0.0211lg/1 or 21ng/1. This concentration, while very low, is equivalent to the limit of TBT known to cause a chronic impact on the growth or development of marine organisms. Therefore one discharge alone has the potential to affect marine life in the zone affected by the plume. Impacts on marine organisms could be significant when cumulative concentrations of TBTs released from non
Axis Environmental Consultants Ltd AXV/513//92-000 Page 55
Hongkong United Dockyards Ltd - Extension to TYTL I08R? Proposed reclamation and relocation of United Floating Dock Environmental Impact Assessment- Final Report
point sources (particularly the large number of ships using the Ma Wan Fairway) and other discharges from floating docks are considered.
In Yam 0 Wan where there are 5 floating docks operating within a relatively small area, concentrations of TBTs in the water column may reach significantly elevated levels. This is of concern given that the discharge disperses over an area known to be used by the Chinese White Dolphin. The edge of the plume also reaches the Fish Culture Zone at Ma Wan but levels of TBT are not expected to be harmful to fish life.
The discharge from Tsing Yi is also of concern as the sediment plume reaches the coastal waters off 7 gazetted beaches. Concentrations of TBTs attributable to the United would however be very low and in the order of 0.2ngll, one hundred times smaller than the concentration known to affect marine life. Since the cumulative effect in the coastal waters of the discharge from the two docks at HUD's facility is below the level known to impact on marine life and the material is likely to settle out of the water column quickly, the impact on bathing water quality is not significant.
For all Scenarios, maximum concentrations of TBTs and other contaminants released in process waters occur in the immediate vicinity of the dock where there are no sensitive receivers.
Sedimentation rates are of greater concern since TBTs and metals are able to persist in the environment for greater periods of time once they are removed from the water column where they may then reach toxic levels. The model indicates that the maximum rate of sedimentation at the end of the tidal run was 30 glsq m.. As stated above, TBT release rate over a washdown period is estimated to be in the order of 0.0052 glsec. The maximum deposition rate, without considering any reduction caused by filtering etc., would therefore be 0.156mg TBT/m2
•
Under Scenario 3 therefore TBTs could reach harmful levels along the west coast of Tsing Yi and the south coast of the western New Territories. Similarly for Scenario I, the existing situation concentrations can reach toxic levels in sediments along the north Lantau coast. Of the three modelled Scenarios, Scenario 2 is the preferable option.
Axis Environmental Consultants Ltd AXV1513/192-000 Page 56
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1
EPD TECHNICAL CIRCULAR No 1-1-92
ApPENDIX 6
Ref: EP [00IC[0/[6 Environmental Protection Department 281F., Southom Centre [30 Hennessy Road Wanchai, Hong Kong.
9 November 1992
ENVIRONMENTAL PROTECTION DEPARTMENT
TECHNICAL CIRCULAR NO. (TC) NO 1-1-92
Classification of Dredged Sediments for Marjne Djsposal
1. In fulfilment of my responsibility as the designated officer under paragraph 2(1) in Schedule I of the Dumping at Sea Act 1974 (Overseas Territories) Order. 1975, I wish to notify you that dredged sediments will be classified as indicated below for the purpose of issuing licences under the Act. This circular should be read in conjunction with the Works Branch Technical Circular No. 22/92 - Marine Disposal of Dredged Mud which outlines. the procedures to be followed in all works, whether public or private, which involve the marine disposal of dredged sediments.
2. Sediments will be classified according to their level of contamination by toxic metals. The classes are defined as follows:
Class A . Uncontaminated material, for which no special dredging, transport or disposal methods are required beyond those which would normally be applied for the purpose of ensuring compliance with EPD's Water Quality Objectives, or for protection of sensitive receptors near the dredging or disposal areas.
Class B Moderately contaminated material, which requires special care during dredging and transport, and which must be disposal of in a manner which minimizes the loss of pollutants either into solution or by resuspension.
Class C Seriously contaminated material, which must be dredged and transported with great care, which cannot be dumped in the gazetted marine disposal grounds and which must be effectively isolated from the environment upon final disposal.
AXIS Environmental Consultants Ltd. APP1.1
~ metallic element to be exceededror-sediments to be Identmea as railing· within a particular class.
..
Table A - Classification of Sediments by Metal Content (mg/kg dry weight)
Cd Cr Cu Hg Ni Pb Zn
Class A 0.0-0.9 0-49 0-54 0.0-0.7 0-34 0-64 0-140
Class B 1.0-1.4 50-79 55-64 0.8-0.9 . 35-39 65-74 150-190
Class C 1.5 or 80 or 65 or 1.0 or ·40 or 75 or 200 or more more more more more more more
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Note: Test results should be .rounded off to two significant figures before comparing 0 with the table, e.g. Cd to the nearest O.1mg/kg, Cr to the nearest 1 mg/kg, and _ Zn to the nearest 10 mg/kg, etc.
( Stuart B. Reed)· Director of Environmental Protection
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ANALYTICAL PROCEDURES FOR TBTs
ApPENDIX 7
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APPENDIX 7 TBT Analysis
The analytical procedure for TBTs is as described in the report produced by CSIRO. It should be noted that there are presently great difficulties in obtaining results for TBTs. CSIRO are government laboratories in Australia and are the only commercially available service who achieve consistent results. Unfortunately, due to demand there is currently at least a 3 month waiting period between sending in samples and obtaining data which does not meet USEPA requirements for storage of samples.
Axis Environmental Consultants Ltd A)(V/5/3//92-000 Page 57
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2 1 APR 1995
COMMONWEALTH SCIENTIFIC AND INDUSTRIAL RESEARCH ORGANISATION
DIVISION OF FUEL TECHNOLOGY
CENTRE FOR ADVANCED ANALYTICAL CHEMISTRY
INVESTIGATION REPORT FT/IR007
ANALYTICAL PROCEDURES FOR BUTYL TIN
COMPOUNDS IN ENVIRONMENT SAMPLES
by
G.E. Batley Chen Fuhua l
C.L Brockbank K.J. Flegg
June, 1988
1 Department of Environmental Science, Nankai University
Tianjin People's Republic of China
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CONTENTS
Page
1. INTRODUCTION
2. EXPERIMENTAL 4
2.1 Reagents and Standard Solutions 4
2.2 Apparatus 5
2.3 Analysis of Waters 6
2.4 Analysis of Biota 7
2.5 Analysis of Sediments 7
2.6 Measurement Procedure 8
3. RESULTS AND DISCUSSION 9 f •
i .( 3.1 Sample Pretreatment 9
3.2 Hydride Generation and Detection 10
3.3 Detection limits and Reproducibility II
4. CONCLUSION 12
5. REFERENCES 12
Figure 1 Apparatus for hydride generation - AAS determination of alkyltins
Figure 2 Quartz furnace
Figure 3 Separation of tin species in a sediment extract using hydride generation -
AAS
" I Figure 4 Calibration graph for tributyltin
Figure 5 Calibration graph for dibutyltin
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INTRODUCTION
The increasing use of butyltin compounds both as biocides and in plastics
manufacture and the demonstrated toxicity of these compounds to some aquatic biota
at concentrations as low at 20 ng Sn L -I (His and Robert, 1985), has necessitated the
development of highly sensitive procedures for their detection in aquatic systems.
Since the toxicity of butyl tin compounds decreases in the order tributyltin (TBT) >
dibutyltin (DBT) > monobutyltin (MBT) > inorganic tin, it is essential that the
analytical method separate these species, as well as preconcentrating them by as
much as three orders of magnitude to enable their detectiop at natural solution
concentrations in the parts per trillion range.
Tributyltin can be extracted with 100% efficiency from aqueous solutions using
a range of non-polar solvents such as benzene, toluene, hexane, pentane or
dichloromethane (Hattori et a!., 1984; Matthias et a!. 1986; Meinema et a!., 1978;
Mueller, 1978, 1984; Tsuda et aI., 198,7; Valkirs et aI., 1986); however, the efficiency
of butyl tin extraction is progressively decreased with dealkylation. Monobutyltin is
too polar to be extracted from water into an organic solvent (Mueller, 1984) while
the efficiency of DBT extraction lies in the range 60-80% (Meinema et aI., 1978).
In most instances, dichloromethane is the solvent of choice, since the use of
benzene is now prohibited in most laboratories on the grounds of occupational
health. Only when using GC with electron capture detection should halogenated
organic solvents be avoided because of their electron-capture properties, and
replaced by hexane or pentane.
The simultaneous solvent extraction of inorganic tin and the three butyltin
compounds is possible only after the addition of a complexing agent (Meinema et aI.,
1978). Tropolone (2-hydroxy-2,4,6-cycloheptatrien-l-one) has been widely used for
this purpose (Maguire and Huneault, 1981; Mueller, 1984). The use of bonded
octadecylsilanes as solid phase adsorbents, precoated with tropolone, offers
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considerable promise as a rapid preconcentration method (Matthias et aI., 1987;
Mueller, (987).
The use of high performance liquid chromatography (HPLC), investigated by
several workers (Ebdon et aI., 1985; Jewett and Brinckman, 1981; Matthias et aI.,
1987; Vickrey et aI., (980), -has the advantage over GC methods that no prior
conversion to volatile species is required. Jewett and Brinckman (1981) separated
TBT and DBT using a cation exchange column and methanol/water/ammonium
citrate mobile phases. No separations have, however, been reported for the full
range of TBT degradation products likely to be encountered.in natural waters or
sediments, and the method is only suited to TBT analysis.
Detection requires a sensitive yet specific detector. Experiments in our
laboratory (Payne and Batley, (987) have found a dropping mercury electrode
electrochemical detector to be insufficientlY sensitive, while satisfactory column
separation of TBT, DBT and mono butyl tin could not be achieved. MacCrehan (1981)
was able to detect 2.3 ng TBT using a gold amalgam detector electrode.
Atomic absorption spectrophotometry (AAS) is a highly selective detection
method for many organometals, however coupling the detector to the HPLC effluent
stream is difficult (Batley and Low, (988). Tin is poorly detected by AAS unless
atomized in a hydrogen-rich flame. Detection limits near 200 ng Sn were obtained
using a slotted tube atom trap (Ebdon et aI., (985), while discrete volume
nebulization into a graphite furnace allowed detection of 30 ng Sn (Jewett and
Brinckman, (981). Preliminary preconcentration is still required for HPLC analyses
of natural samples.
Gas chromatographic analysis of butyl tins requires their conversion to volatile
species either by hydridization or alkylation, the former being more universally
employed .. Alkylation reactions have included methylation (Mueller, (984),
ethylation (Mueller, (978), butylation and pentylation (Maquire and Huneault, 1981;
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Maguire and Tkacz, 1983), by reaction with the appropriate alkylmagnesium halide
after extraction of the butyltins or their tropolone complexes into organic solvents.
Hydridization has been carried out both after extraction of butyltins into non
aqueous solvents (Hattori et aI., 1984; Matthias et aI., 1986; Tsuda et aI., 1986;
Valkirs et aI., 1986) or by simultaneous extraction and hydridization (Matthias et aI.,
1986) by reaction of the sample with sodium borohydride in the presence of added
solvent, usually dichloromethane. Matthias et al. (1986) reported greater recoveries
using the simultaneous procedure.
Capillary, megabore and traditional packed columns have been used for the GC
analysis of TBT. The superior resolution achievable by capillary and mega bore
columns can be an advantage, particularly where the detection system lacks
selectivity, e.g. with electron capture detection. Advocates of packed columns prefer
their ease of handling and convenience in assembly.· Furthermore, in some
environmental samples, oils, fats, protein debris and other organic residues present
can deposit on the column, degrading performance. Packed columns, however, can
be more easily cleaned up by replacing part of the packing material Or even
repacking the entire column.
Of the detectors commonly available as accessories to modern commercial GC
instruments, both the electron capture and flame photometric detectors are suited to
tin analysis. The electron capture detector is the most sensitive, but not the most
selective since many organic compounds, especially halogenated organics, display
electron-capturing ability. The GC separation must be optimized to minimize such
interferences. Flame photometric detectors are less common GC detectors, but
provide effective interference-free measurement of tin species if modified with a
600-2000 nm band-pass filter to detect the SnH emission band, and using a
hydrogen-rich flame (Mueller, 1978). Detection limits near 0.2 pg have been
obtained (Aue and Flinn, 1977). The majority of methods using capillary column
GC have indeed used flame photometric detection.
i.\
4
The purge and trap method described in this report (Donard et aI., 1986;
Jackson et aI., 1982; Randall et aI., 1986), uses direct sample hydridization with
cryogenic trapping of the butyl tin hydrides on a column, typically 30 mm x 6 mm
diameter, packed with an adsorbent such as 3% OV-I on Chromosorb W, in the size
range 40-100 mesh. Typically, tin compounds from a sample or sample extract are
converted to the hydrides by reaction with sodium borohydride, and trapped on the
packed column. Selective volatilization is achieved by application to the trap of a
linear heating ramp to 200 ·C, with the displaced hydrides being carried by a helium
gas stream, then introduced with added hydrogen and oxygeI! gases into a heated
quartz furnace located in the burner mount of an atomic absorption spectrometer
(AAS). This method is the most sensitive of the TBT techniques while permitting
the simultaneous determination of not only TBT but DBT, MBT, inorganic tin and
the range of methyltin compounds.
Pinel and Madiec (1986) attempted to simplify this procedure by measuring
"heavy" (lOW VOlatility) tin and light tin as differentiated by their retention in a silica
gel trap maintained at -48 ·C. Tributyltin and some DBT were retained, while MBT,
methyltins and inorganic tin were considered .to be "light" and were not trapped.
Total tin was determined after U.V. mineralization, and "heavy" tin by difference.
This report describes in detail experimental procedures for the determination of
alkyl tins in water, sediments and biota including an operational proposal for the
purge-and-trap AAS method.
2. EXPERIMENTAL
2.1 Reagents and Standard Solutions
Tri-n-butyltin chloride (95+%), di-n-butyltin dichloride (96.5%) and mono-n-
butyltin tri-chloride were obtained from Alfa Products, Danvers, Mass. USA. Each
week, stock standard solutions (1000 mg Sn L -I in ethanol) were diluted with
ethanol to prepare 50 mg L-I working standards. All standard solutions were stored
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at 4·C in polycarbonate bottles. Analytical reagent hexane and dichloromethane were
obtained from Ajax Chemicals, Sydney. Tropolone (Sigma Chemical Company, St
Louis, MO, USA) was used in a 0.05% solution in hexane or dichloromethane.
Sodium borohydride (Alpha Inorganics) was prepared as a 4% (W IV) solution,
with addition of 0.4 g potassium hydroxide per 100 ml of solution to inhibit
decomposition. The solution was filtered through a 0.45 }lm filter before use. All
glassware was decontaminated between samples by rinsing with acetone, soaking with
detergent for one hour and then rinsing thoroughly with distilled water.
Polycarbonate bottles were soaked in dilute nitric acid, ·then ~oaked with detergent
and rinsed with distilled water as above.
2.2 Apparatus
The apparatus, illustrated in Figure I, comprises a hydride generator, transfer
line, Teflon column and quartz furnace. The hydride generator consists of a 100 mL
Pyrex reaction vessel (Omnifit Ltd, !'lew York, NY, USA) having three Teflon inlet
valves. One of these valves was removed and replaced with a Teflon-backed rubber
septum in a Teflon holder. The second valve was connected to a helium gas supply
with a Teflon tube carrying gas to immediately above the surface of the sample. A
Teflon transfer line (1.5 mm Ld.) was connected to the remaining valve. Before use,
the reaction flask was washed with detergent, allowed to stand in 7% nitric acid
overnight, then rinsed with distilled water and siliconized. During a batch of
determinations, it was rinsed with distilled water only. For hydridization, sodium
borohydride solution was introduced using a polyethylene syringe with a long
stainless steel needle. The reaction vessel contained a .circular-mounted stirrer bar,
rotated by a high speed magnetic stirrer.
The hydride line was connected by an Omnifit universal variable connector to a
U-shaped Teflon column (36 cm 4.5 mm Ld.) filled with 2.5 g of a chromatographic
packing prepared by rotary evaporation of 3% OV -10 I in chloroform onto
Chromosorb G-A W-DMCS 45-60 mesh (Alltech Associates, Deerfield, III., USA).
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The column and the line were each coiled with alSO W /metre electrothermal heating
tape (Email Industries, Sydney, Australia) and independently controlled by a, variable
transformer. The temperature was measured via a thermocouple having a digital
display.
The outlet of the trap was connected directly to the quartz furnace whose
dimensions are shown in Figure 2. This furnace was wound with Nichrome wire
connected to a variable transformer. Again a thermocouple was used to determine
the voltage settings to give the desired furnace temperature. The quartz furnace was
attached to an insulated platform which could be fitted.in thy burner mount of. a
Varian-Techtron model AA4 atomic absorption spectrometer. Hydrogen gas was
supplied through the first inlet and oxygen through the second, to mix with the
hydride-containing helium gas stream before entering the quartz furnace.
2.3 Analysis of Waters
Freshly collected samples should be stored in polycarbonate containers. Dooley
and Hamer (1983) showed that at 4·C, seawater samples stored in polyethylene lost
up to 62% of TBT after I week's storage. Losses of less than 3% were observed for
polycarbonate bottles, while Teflon and Pyrex containers removed 7 and 4%
respectively. Frozen seawater samples containing tributyltin at sub I'g L-I
concentrations showed insignificant losses over 4-5 weeks but only about half the
initial tributyltin, concentration was present after 10 months (Valkirs et aI., 1986).
For analysis of natural waters at least 500 mL of sample is desirable'to obtain
detection limits near I ng Sn L - I. The unfiltered sample (500 mL) is added to a
separating funnel and shaken for 2 min each with 25 mL and 10 mL of 0.05%
tropolone in hexane. The first extract is separated into a 50 mL. pear-shaped flask
and evaporated on a rotary-evaporator to a volume of approximately 10 mL, then
combined with the second extract and 5 mL of 0.05 M HN03, for evaporation at
40·C under a stream of nitrogen. A further 5 mL of 0.05 M HN03 is added and
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5 mL aliquots transferred to the 100 mL Pyrex reaction vessel with the addition of
15 mL of 0.05 M RN03, for hydridization.
2.4 Analysjs of Biota
Samples of oysters, fish tissue Or other biota are homogenized in a Waring
blender and the homogenates transferred to 50 mL polycarbonate vials and stored in
a freezer prior to analysis. For oysters, up to four samples are generally pooled for
homogenizing, otherwise a smaller blender is required.
For analysis, 0.2 g of thawed homogenate is weighed into a stoppered glass
centrifuge tube and 5 mL of concentrated HCl and 5 mL of methanol added. The
sample is treated in an ultrasonic bath for 1.5 h, shaken to break up any lumps then
ultrasonicated for a further 0.5 h to complete the extraction. To this is added 15 mL
of 0.05% tropolone in distilled dichloromethane, and the mixture shaken for
20-30 min, then centrifuged for 10 min. Using a pasteur pipette, the bottom organic
layer is then removed into a measuring cylinder, and 12 mL of the dichloromethane
extract returned to the centrifuge tube, after prior rinsing out successively with
acetone and distilled water. Ten mL of 0.05 M nitric acid analytical reagent grade,
is then added and the dichloromethane evaporated under a stream of nitrogen.
The acidic solution is then filtered through a 0.45 pm disposable membrane
filter fitted to a 10 mL disposable polyethylene syringe. Both filter and syringe are
rinsed with 2 mL 0.05 M HN03 and the washings added to the filtrate and the
mixture diluted to -20 mL with more 0.05 M HN03, and added by pipette to the
Pyrex reaction vessel prior to hydridization. For samples containing high TBT
concentrations (>200 ng Sn g-I) smaller aliquots or a smaller initial volume are taken.
2.5 Analysis of Sediments
Typically the equivalent of 10 g (dry weight) of sediment is used for butyltin
analysis. Extraction procedures generally involve refluxing the sediment for several
hours using a solvent suitable for the subsequent measurement procedure. Hattori et
at. (1987) used concentrated HCl/methanol (5:95) followed by extraction with
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benzene; however, others have used hexane, dichloromethane or benzene/tropolone
(Humphrey and Hope, 1987; Maguire et aI., 1985; Tsuda et aI., 1986). The extract is
generally separated by either filtration of centrifugation. The procedure described in
2.4 for biota, however, applies equally well to sediments.
To avoid losses the sample for analysis should not be dried. Instead, after
homogenizing, a 0.5-1.0 g sub-sample is taken for analysis and a separate sample for
moisture analysis. The sub-sample is mixed in a stoppered Pyrex centrifuge tube
with 5 mL of concentrated HCI and 5 mL of methanol, then ultrasonicated for 90
minutes. The mixture is centrifuged to separate the sediment which is washed then
centrifuged again with a further 10 mL of the HCl/methanol mix. The acid extracts
are then combined and solvent extracted with IS mL of 0.05% Tropolone in
dichloromethane and back-extracted with nitric acid as described in 2.4. The extract
may be diluted as required and an aliquot taken for hydridization.
2.6 Measurement Procedure
The prepared sample (20 mL) having an acidity of 0.05 M HN03 is added to the
hydride generator reaction vessel. With helium gas metered through the vessel at
300 mL min-I, the magnetic stirrer is turned on for· I min to a fast speed to ensure
a deep vortex, while 1.6 mL of 4% sodium borohydride solution is added by syringe.
The generated hydrides pass along the transfer line, heated to 90·C and are trapped
in the column which is immersed in a dewar flask of liquid nitrogen. Four minutes
later, a further 1.4 mL of borohydride solution is added and the reaction allowed to
proceed for a further 4 min. The stirring is stopped and the liquid nitrogen
removed. After 1.5 min, the furnace heating is commenced. Initially 35 V is
applied until the column temperature increases to -40· (about 0.9·C s-I), then 140 V
applied until TBT elution (about 1.5· C s-I). The separated hydrides in the helium
gas stream are successively mixed with hydrogen (800-900 mL min-I) and oxygen
(20-35 mL min-I) before being swept into the quartz furnace which had been
preheated to 800 ·C.
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The tin absorbance peaks are measured at 224.61 nm using 300 I'm slit width,
IO-fold scale expansion and the signals recorded on a chart recorder. The peak
area is quantified by triangulation using a t base x height calculation.
3. RESULTS AND DISCUSSION
3.1 Sample Pretreatment
The conditions for sample preparation described in the preceeding section were
selected to maximize the extraction efficency of TBT from each of the sample types.
The choice of hexane or dichloromethane as a solvent was dicta fed by whether it was
desirable to have the, extracting solvent at the lower or upper layer. With water
samples, use of hexane avoids any suspended sediment which collects at the bottom
of the separating funnel. In the case of biota and sediment samples, dichloromethane
is chosen because hexane was found to evaporate during the necessary centrifugation
stage.
The extraction of TBT from biota is particularly difficult, especially if the
analytical method requires a large sample size (e.g. 10 g) to obtain both satisfactory
C phase separations during th'e extraction and a suitable detection limit., In the
procedure described in this report, it was possible to take as little as 0.2 g of sample.
[ Even so, a lengthy period of ultrasonication was required before complete
Ie solubilizing or suspension of the fatty tissue was accomplished. The time required
may vary for particular sample types and is best determined by experiment. The ,
L subsequent extraction was performed using a mechanical wrist-action shaker, where
it was found that 20-30 minutes Shaking gave better recoveries than 10 minutes. No
[ additional TBT was obtained by a second extraction., It should be noted that washing
of the extract with sodium hydroxide as recommended by some authors
(Wolniakowski et aI., 1987), was found to result in losses of TBT and was omitted.
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3.2 Hydride Generation and Detection
The sensitivity, reproducibility and separation of butyltin hydrides is critically
dependent on the conditions used for hydride generation and detection. Many of
these factors have been addressed by Randall et al. (1986), including the need to heat
the transfer lines, the desirability. of a Teflon rather than a glass column, and the
suitability of different column packing materials. Important also are the gas flow
rates, and it was found, for example, that a high helium flow rate in the range
200-400 mL min-I was best for reducing the noise level of the final signal. No
difference to the output signal was observed using hydrogen .and oxygen flows of
1600 mL min-I and 90 mL min-I respectively, compared with respective flows of
800 mL min-I and 20 mL min-I. The presence of both oxygen and hydrogen has
been shown to be essential in maximizing the absorbance signal due to tin
atomization (Donnard et aI., 1986).
The helium gas inlet to the re.action flask was best located near the solution
surface to prevent solution from flowing back in the gas inlet tube under the slight
pressure of hydrogen from the hydridization reaction. In addition, the lifetime of
the column packing was increased, as less water vapour was carried into the column.
Under these conditions, up to 25 runs could be undertaken. Note that no water trap
was included in our apparatus, although traps have been used to increase column
lifetime (Donard et aI., 1986). It was felt that additional surfaces would only
increase the opportunity for losses of tin hydrides.
The reproducibility of analytical results was dependent on the precise timing of
the steps in the hydride generation, trapping and thermal desorption stages. The
sensitivity could be improved by appropriately increasing the rate of heating applied
to the column, as long as the resolution of peaks was not lost. A heating rate of
1.5"C s-I was chosen in this study.
The furnace design was also critical (Figure 3), especially the relative positions
of both the hydrogen and oxygen inlets. It was noted that the output signal was
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After continuous furnace operation, a white deposit gradually built up on the
, 0 interior surface of the furnace, and diminished the output signal. This situation
could be partly overcome by rinsing the inside surface with water, although
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eventually the furnace needed to be replaced. No differences in output signal or
furnace lifetime were observed by Changing the furnace temperature from 750·C to
900·C and 800·C was used routinely.
3.3 Detection Limits and Reproducibility
A typical output signal shown in Figure 4, indicates the good resolution
achieveable between TBT, DBT, MBT and inorganic tin. Peak areas were shown to
be less sensitive than peak heights to small changes in conditions and were therefore
used in all measurements. A chart speed of 5 cm min- I chosen to facilitate area
measurements.
Recoveries were assessed by standard additions, to both the samples before
extraction and to the test solution added to the reaction flask. Quantitative
recoveries were found in all cases. For calibration purposes, standard additions to
the test solutions were used. Typical calibration curves are shown in Figures 5 and
6.
On the basis of the above, detection limits of 0.3 ng Sn and 1.0 ng Sn
respectively were obtained for TBT and DBT. This translates to limits for TBT of
0.6 ng Sn L -I in waters and 1.2 ng Sn g-I in biota, using the methods outlined in
2.3 and 2.4 above.
The use of graphite furnace atomic absorption spectrometry to detect only TBT
in tissues and sediments after dichloromethane extraction, has been described
L' recently by Stephenson and Smith (1988). While the method is inherently simpler
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than that described above, it is restricted to TBT only and the detection limit is
considerably poorer, requiring a sample mass of ten grams to detect Ing Sn g-I.
4. CONCLUSIONS
Butyltin species are best extracted from waters, sediments and biota using ·0.05%
tropolone in hexane or dichloramethane with subsequent back-extraction into 0.05 M
nitric acid. The extracts are reacted with sodium borohydride to form the respective
hydrides which are trapped on a chromatographic column and then thermally
desorbed for detection in a quartz furnace by atomic absorption spectrometry. This
method has a detection limit of 0.3 ng Sn as TBT which is equivalent to
0.6 ng Sn VI in waters and 1.2 ng Sn g-I in sediments and biota based on 500 mL
and 0.2 g samples respectively.
·5. REFERENCES
Aue, W.A. and Flinn, C.J., 1977, A photometric tin detector for gas chromatography,
J. Chromatogr., 142, 145-152.
Batley, G.E. and Low, G. K-C, 1988, Applications of high performance liquid
chromatography to trace element speciation studies, in "Trace Element
Speciation, Analytical Methods and Problems, G.E. Batley, ed., CRC Press,
Miami, in press.
Batley, G.E., Mann, K.J., Brockbank, C.l. and Maltz, A., 1988, Tributlytin in
Sydney Harbour and Georges River waters. Aust. J. Mar. Freshwater Res. in
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Donard, O.FX., Rapsomanikis, S. & Weber, J.H., 1986, Speciation of inorganic tin
and alkyltin compounds by atomic absorption spectrometry using electrothermal
quartz furnace after hydride generation, Anal. Chern., 58, 772-777.
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e 8
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13
Dooley, C.A. and Homer, V., 1983, Organotin compounds In the marine
environment: uptake adsorption behaviour, Naval Ocean Systems Center
Technical Report No. 917, San Diego, USA, 19p.
Ebdon, L., Hill, S.J. and Jones, P., 1985, Speciation of tin in natural waters using
coupled high-performance liquid chromatography-flame atomic-absorption
spectrometry, Analyst, ill, 515-517.
Hattori, Y., Kobayashi, A., Takemoto, S., Takami, K., Kuge, Y., Sugimae, A. and
Nakamoto, M., 1984, Determination of trialkyltin, dialkyltin, and triphenyltin
compounds in environmental water and sediments, J. Chromatog., 315, 341-346.
His, E. and Robert, R., 1985, Development des veligeres de Crassostrea gigas dans Ie
bassin d'Arcachon etudes Sur les mortalities larvaires, Rev. Tran. Inst. Peches.
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Humphrey, B. and Hope, D., 1987, Analysis of water sediments and biota for
organotin compounds, in "Ocean 87", Volume 4, Organotin Symposium
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Jackson, J.A., Blair, W.R., Brinckman, F.E. and Iverson, W.P., 1982, Gas-
chromatographic speciation of methylstannanes in the Chesapeake Bay using
purge and trap sampling with tin-selective detector, Environ. Sci. Techno!., 1.2.,
110-116.
Jewett, K.L. and Brinckman, F.E., 1981, Speciation of trace di- and triorganotins in
water by ion-exchange HPLC-GFAA, J. Chromatogr. Sci., li, 583-593.
MacCrehan, W.A., 1981, Differential pulse detection in liquid chromatography and
its application to the measurement of organometal cations, A nal. Chern., 53,
74-78.
Maguire, R.J. and Huneault, H., 1981, Determination of butyl tin species in water by
gas chromatography with flame photometric detection, J. Chromatogr., 209,
458-462.
.~
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, . - \
\ I
!
14
Maguire, R.J. and Tkacz, R.J., 1983, Analysis of butyltin compounds by gas
chromatography; comparison of flame photometric and atomic absorption
spectrophotometric detectors, J. Chromatogr., 268, 99-101.
Maguire, R.J., Tkacz, R.J. and Sarter, D.L., 1985, Butyltin species and inorganic tin
in water and sediment of the Detroit and St. Clair River, J. Great Lakes Res.,
II, 320-327.
Matthias, C.L., Bellama, J.M. and Brinckman, F.E., 1987, Determination of
tributyltin in estuarine. water using bonded C 18 silica solid phase extraction,
hydride derivatization and GC-FPD, in ·Oceans 87", Volume 4, Organotin.
Symposium Proceedings, Marine Technology Society, Washington, D.C.,
1344-1347.
Matthias, C.L., Bellama, J.M., Olson, G.J. and Brinckman, F.E., 1986,
Comprehensive method for determination of aquatic butyltin and butylmethyltin
species at ultratrace levels using simultaneous hydridization/extraction with gas
chromatography-flame photometric detection, Environ. Sci. Techno!., 20,
609-615.
Meinema, H.A., Burger-Wiersma, T., Versluis-de Hahn, G. and Gevers, E. Ch. 1978,
Detection of trace amounts of butyl tin compounds in aqueous systems by gas
chromatography/mass spectrometry, Environ. Sci. Techno!., 11., 288-293.
Mueller, M.D., 1978, Comprehensive trace level determination of organotin
compounds in environmental samples using high-resolution gas chromatography
with flame photometric detection, Ana!. Chern., 59, 617-623.
Mueller, M.D., 1984, Tributyltin detection at trace levels in water and sediments
using GC with flame-photometric detection and GC-MS, Fresenius Z. Anal.
Chern., 317,32-38.
Payne, E.J. and Batley, G.E., 1987, unpublished results.
[
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15
Pinel, R. and Madiec, H., 1986, Determination of "heavy" organotin pollution of
water and sh~lIfish by a modified hydride atomic absorption procedure, Intern.
J. Environ. Anal. Chem., 27, 205-271.
Randall, L., Donard, O.F.X. and Weber, J.H., 1986, Speciation of n-butyltin
compounds by atomic absorption spectrometry with an electrothermal quartz
furnace after hydride generation, Anal. Chim. Acta. 184, 197-204.
Stephenson, M.D. and Smith, D.R., 1988, Determination of tributyltin in tissues and
sediments by graphite furnace atomic absorption spectrometry, Anal. Chern .. 60,
696-698.
Tsuda, T., Nakanishi, H., Aoki, S. and Takebayashi, J., 1987, Determination of
butyltin and phenyltin compounds in biological and sediment samples by
electron-capture gas chromatography, !. Chromatogr., 387, 361.
Tsuda, T., Nakanishi, H., Morita, T. and Takebayashi, J., 1986, Simultaneous gas
chromatographic determination of dibutyltin and tributyltin compounds in
biological and sediment samples, !. Assoc. Off. Anal. Chern., 69, 981-984.
Valkirs, A.O., Seligman, P.F., Stang, P.M., Homer, V., Lieberman, S.H., Vafa, G.
and Dooley, C.A., 1986, Measurement of butyl tin compounds in San Diego Bay .
Mar. Poilu!. Bull., 17, 319-324.
Vickrey, T.M., Howell, H.E., Harrison, G.V. and Ramelow, G.J., 1980, Post column
digestion methodS for liquid chromatography-graphite furnace atomic absorption
speciation of organolead and organotin compounds, Anal. Chern. 52, 1743-1746.
Wolniakowski, K.U., Stephenson, M.D. and Ichikowa, G.S., 1987, TributYltin
concentration and oyster deformations in Coos Bay, Oregon, in "Oceans 87", Vol.
4., Organotin Symposium Proceedings, Marine Technology Series, Washington,
D.C., 1438-1772.
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TIME, MINUTES
Figure 3 Separation of tin species in a sediment extract using hydride generation - AAS
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CORRESPONDENCE WITH TRANSPORT
DEPARTMENT REGARDING TIA
ApPENDIX 8
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MaUll!.cll Consultants Asia Ltd, 4 FUl'Ig Wo Lane, Wo Che <:;ha Tin' ,-lew Territories
A\t~l1tion: Mr. Y . M. YONG
Dear Sir,
------,'RANSPORT DEFAR'/"MEI\lT
Urban (Kin.) a, NT RegiOlla! Offices 7'~&BthFI ...... Mong lC.ak GoYemrnent Ofrace.r. 30 L.ullft W." Sner. Kowloon. Hong Kong. Fox No" 2381 3799 (NTRO)
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o Proposed North Ya,"! ExtC.ISioll Oil TYTL 108 RP at Hongkong United Dockyard Ltd, Tsing Vi
Tr:lffic Imp:tct Assessment
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We rerer tQ'~your above quoted reference letter of 12.4.96 Itnd are ple2.sed to advise that we have no fur.ller COlTUnent to make on your submitted tr .. mc impact assessment r~port for the above devel :rpment extension, '
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Yours fai!nfi. IIy.
~p.~ (Ricky LEUNG)
for Assis(ant Commissioner for T"lInsporllNT
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HONG ICONG TEL (852) 28Q! 8262 FAX (852) 2591 2549
Your Ree( ) in NR 15711611TY11--108 Our Ret: YYM;af;92695102.2·0113 12th Apn1 1996
Assistant ':ommissioner for Transport Transport I)epartment " Urban (Kl:.;) & NT Regional Offices 7th & 8th Floors
By fax ad post [2381 3799(N:RO»)
Mong Kok Government Offices 30 Luen Wan Street Kowloon
Attn: Mr T.R Leung
Dear Sir,
subject.
'Proposed North Yard Extension on TYTL 108 RP at Hongkong United DoclcyardLtd, Tsing Yi
Traffic Impact Assessment
Thank you for your letter of 23.3.96 giving no adverse comment to the above
We are pleased to confIrm the following:
(i) The fill materials for the reclamation" is.expected to either come :rom the Pearl River or surplus materials from the adjacent Lantau Fixed Crossing site. Fill from both sources should not require road transpor.ation to site. Only minor construction traffic is expected relating to the transportation of ready mbc concrete for seawall coping. ~ement and olher minor works. Such road transport would spread over a construction period of 6 to 9 months and is not expeeted to cause a problem.
(ii) The proposed fuMe usage of lhe existing land next to lhe Engineering Complex. (after relocation of present container Storage yard) will be for marine repair activities which would not generate additional road traffic.
We trust that the above clarification is to your satisfaction.
Yours faithfully for MAUNSEI.L CONSULTANTS ASIA L 1D
~l (Y.M. Yong)
cc HUD (Attn: Mr K.W. Tong) fa;( no. 2433 0180 tu\~: JW'JOIItIoU ~.F S, ~~QIIIIIDI. UG.WI!IfTV CN"",IIJ ~'NCllDI'l',UTt,1UIt.M ItcUf"O C $L£f, ra. T~l J t)rOO1l'7, 1 tl9'I.M. lOW T \fIItIIG. ASScx:lATtS: l slJt "."..;. Ie CI1ftiD. A S rtOt,ll rYOC. s,. ~. ,r fOJIO. f K iii OWl. J C I ...... ,. S l1~." "F ~ AI. wtJ. eDlII5U.l.I.In': .A ....... lOfI.
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Mr W.K. Tong ------------':... .. _._--_._--FROM Joseph Wong
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HONG K:::lNG TE!. '(&Sl),26CS 6262 !=AX (SS?) 215~' 2e·n
OATE 28th March 1996
FAX-NO. 2433 alSO
SIiEET 1 C'F 2 .. __ ._. __ ._------_._---~eF NO. JW:kly:92695jOl·Ol05 ------SUBJECT MUD North Yard Ex(ension
fume Impact A?ses~ment
We enclose a copy for the letter from TD of 23rd March 1996 responding 10 our application for a waiver to a full TIA.
Referring to the comment in paragraph 3 of TO's letter, it is our understanding that the future usage the existing land (presently occupied by Ocean Crown) is for marine repair activities and such activities would nOt generate additional land traffic to and from the site 3S compared to the existing configuration. We would clarify ~ith 1D accordingly.
Regards,
End
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.A,\tel"llion: Mr. V . M. YONG
Dear Sir.
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Proposed i'orth Yud Extension on TYTL lOS Rl' lit Hong,kong United Dockyard Ltd. Tsing Yi
TrllfTic JmmlCl A~$t$$l1lent ___ _
j refer to YOUT abc"e q:l,,:ed reference letter of ;''(cr.'!I'l-eung) concerning th~ .b:,,,c su.b,iect.
1 am pleClSed to learn that the eaptioned proposal'wovld not ser.crate ad::!i:ionai traffic, Hence 1 would have no in-prindple objection to it ?,~~umir.g that tn.ns?ort of f,ll materials for ,he r.,clatnation will be ~y l'e~ However.:f road tran<l'''f1 i; required. please ,,'ubmit detai!~ for my further comments.
In the meant:me, clln you clarify the proposed ",~e of t~e .",!::.ng: lane (next 10 :he 'E.i:;iTtcering Co~plt:x) after ;e~o("f'\!.ic~ cf!he prestf'!! cc-mainer Sto!'«g~ ;;-ard to the proposed 'eda;med land
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Assistant COmmissiona- for Transport Transpor: Department Urban ([(In.) & NT Regional Offices 7th & 8t.: Floors Mong Kok Government Offices 30 Luen Wan Street Kowloon
Attn: Mr T.B. Leung
Dear Sir,
MAUNSELL CONSULTANTS ASIA LTD
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" FU~G WO LANE. WO CHE SHA TIN, NE.W TeRRITORIES
HONG KONG TEL (852) 2505 6262 FAX (852) 21591 2649
20th March 1996
By fax and post [2381 3799(:'ITRO)]
Proposed North Yard Extension on TYTL· 108 RP at Bongkong United Dockyard Ltd, Tsing Yi
. '. Traffic Impact Assessment
Since the submission of the TIA Report on 9th January 1996 and our subsequent enquires to your office, we have yet to receive a reply.
As the North Yard Extension Project is running on a very tight programme, we would appreciate an early resolution of any traffic i.ssues that you may be concerned with. We will be most happy to arrange a meeting for the purpose should you see fit to ~~. .
Please do not hesitate to contact the undersigned should you haye any query regarding the TIA Report.
Yours faithfully for MAUNSELL CONSULTANTS ASIA L.ID
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UflJf-l (Y.M. Yong)
co 1H66~·(AUi>::MrNickM.T. Wong)'~ no. 2433 0180
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LETTER OF COMMITMENT FROM HUD TO
IMPLEMENT WATER COLLECTION AND
TREATMENT SYSTEM
ApPENDIX 9
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!XIS EII'IIROIIMEilTAL CONSUWl/TS LTO.
- 4 JUL 1996 Your ref.: EP2/N3/4 lAECE Our ref. : PM-CO-9606 . IVED
ongkong United ockyards Ltd
€/Zi/lj Sa; T50 Wan Road Toing Vi Island New Territories Hong Kong.
Telephone: 2431 2828 Telex ; 43547 HUDHK !-IX Cable : HUDREP HDNGKONG Fax. No. : 2433 0180, 2433 6955
3rd July, 1996.
Environme. ntal Protection Dept., 27/F, SOl'thorn Centre,
By Fax & Post (Fax No .. _259l0558)
130 Hennessy Road, Hong Kong.
Dear Sirr"
Attn.: Mr. Ivan C. Y. Wong. EnvironProtection Officer.
~tension to TYTL lOBRP. Proposed Reclamation and Relocation of Floating Dock" United fl. Endorsement of draft EtA Report.
Refe~ence is made to the First Study Management Group ¥.eeting held on 14.06. :l996 and in response to agreement reached on Item bb in the minutes c.: the meeting we now write to confirm as follows.
Witt .. the relocation of F /D flUnited" to along side the dC1:kyard premises at TSing Yi Island, HUD agrees to undertake to design, experiment a.nd impl-.ment a collection system for wash water from F /D "T:nited". It is envisL.ged at this initial design stage the wash water wonld be pumped through ~, series of pipes and pumps into a tank which would incorporate treatment.s such as filtration and sedimentation. F /D "United" would be the first known floating dock to implement such a system and should the project 1",rove sucessful then HUD will extend this system to their other F/D "What!l?oa" which is also lllOored at Taing Yi Island.
Yours faithfully HONGKONG UNITED DOCKYARDS LTD •
K. W. Tong Production Services Manager
cc: MD, HM. Axis (Attn.: Miss Louise Richards) Fax No. 28272891.
IIOd LIO '01, Sd~~~800 031INn '~'H 0810 88vG GS8 GS: I'. 96, vo ',nr ~
COMMENTS AND RESPONSES ON THE DRAFT EIA REPORT
ApPENDIX 10
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Extension to TYTL l08RP, Proposed Reclamation and Relocation of United Floating Dock, Draft EIA Report
Comments and Responses
(146) in DLO/KT 87/KTLT/82 IV
(2) in PAIS 909/109/14(7)
EP nfR5/8 III
AXT287/1/92000ITC Page·)
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Extension to TYTL l08RP, Proposed Reclamation and Relocation of United Floating Dock, Draft EIA Report
Comments and Responses
!!!!!!!!:!!!!!!iililll,!!;;!!!;;r:;;!:iIillIillllill;1111:111111111!11111111I111:::iij:ii,;i:i!l::::I!lltlllllIII Environmental Protection Department
Ref: EP 21N3/45 II
A. Section 4.2
I. to minimise the impacts on the gazetted beaches between Ting Kau and Sham Tseng of the use of silt curtain, plus working outside bathing season, at least when dredging the contaminated surface layer, should be considered;
B. Section 5.2
I. During a wash down it was estimated that about 6kg of anti-fouling paint would be removed and all this particulate were assumed to be released to the marine water. I have no objection to take this as the worst cast scenario as suggested in the report. But given the housekeeping measures, the amount of anti-fouling paint actually getting into the marine water should be much less than the assumed 6kg. Therefore an assessment should also be carried out with an estimate, taking into account of the housekeeping measures, of the anti-fouling paint being released to the marine water to reflect what is more likely to occur.
AXT287J1/92000ITC
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Noted and agreed. The report will be amended to recommend that a silt curtain should be used whilst dredging the surface sediment, which in parts is classified as grade C contaminated mud. Given the current programme, the dredging work is scheduled to take place late 1996/early 1997 in order to prepare the anchor pockets for the relocation of the dock prior to the onset of the wet season. Even if the project is delayed by a few months the dredging should still take place before the start of the official bathing season (April 1997).
The existing operation is licensed and approved by EPD; the objective of the supplementary EIA is to determine whether the proposed relocation will result in an improvement or a deterioration in the overall impact.
The actual discharge from the dock in terms of TBT is, therefore, effectively irrelevant as even without the collection and filtering system the current housekeeping measures would be adopted, so the actual amount discharged during a washdown would remain the same. Since the relocation will improve efficiency and enable HUD to decommission the Taikoo* (which does not operate the same housekeeping measures) the total released in a year by the relocated United will be less than the amount currently being released at Yam 0 by the combination of United and Taikoo.
Page - 2
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Extension to TYTL l08RP, Proposed Reclamation and Relocation of United Floating Dock, Draft EIA Report
Comments and Responses
I ;;:1;i;;ll;I!!lili11;::1I~!!I!!IIII!lil!:i'lli'lli!i':!1!11:1~;!lllll!!IJ!!!!!!!llllll Environmental Protection Department
Ref: EP 2!N3/45 II
2. When assessing the impacts of TBT only the discharge from United was considered. The cumulative impacts from other sources, such as other floating docks or the large number of ships using Ma Wan Fairway, have not been taken into consideration. To overcome this shortcoming the baseline conditions, which should have already reflected the impacts due to other existing sources of TBT, should first be established. The modelling results, which simulated the
AXT287111920001TC
'The Taikoo will be sold to a Chinese company and it is expected that it will be removed from Yam 0 Wan in October 1996.
For any assumed concentration released from the dock all that is involved is a straight linear conversion (if we assume that 50% of the material is captured by the existing procedures, the predicted concentrations are 50% of those discussed) the concentrations can be easily calculated for any assumed level of reduction as is currently done in the report for the 6kg release rate. No additional modelling is necessary and the current approach conforms with EPD's requirements for considering worst case. Since no information is available to justify any assumed level of reduction, the exercise would appear to conflict with EPD guidance and offers no better basis for assessing the proposed works.
In summary, we feel there is no benefit to carrying out this estimate as we have no basis for estimating the effectiveness of the housekeeping measures, the same housekeeping measures will operate following the relocation, and the purpose of the EIA is to compare the relative impacts of the current location and the proposed location.
We agree in principle that we should consider comparative cumulative impacts. In order to assess the cumulative impact, we will collate as much baseline information as possible in the final report. Determination of the baseline conditions is however very difficult as has been found in the ongoing EM&A work for United. Sediment concentration can be significantly affected by the presence of a single paint chip in the sediment and water concentrations are very dependent
Page - 3
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Extension to TYTL I08RP, Proposed Reclamation and Relocation of United Floating Dock, Draft EIA Report
Comments and Responses
1::!!!illlllll!!;!!!li::';·II;ii;n1!1111111;IIIIIIIi,il1111!111111IjI11111111l1!1i,~III:!lllji::II:1111I111 Environmental Protection Department
Ref: EP 2/N3/45 II
impacts due to United, should then be superimposed onto the baseline to allow for a proper assessment of the cumulative impacts. Reference can be made to previous studies done and the level of contamination of other shipyards. Also the area of the impacts should be given for easy reference;
AXT287l1192000lTC
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on shipping activities. We have no information on the current baseline water quality in terms of TBT in Hong Kong waters, however there is a certain amount of sediment quality data we could use. The CES study undertaken on behalf of EPD in 1994 contains analytical data for shipyards and marinas around Hong Kong and includes some control stations. The previous study for EPD in 1989 contains some historical data which may also be of use. The final report will address cumulative impacts as far as is practicable in order to compare cumulative impacts at the two sites and will refer to location and area of the impact. The report will also incorporate the following:
TBT concentrations have been recalculated to represent a more realistic scenario. Assuming 0.0052g/s of TBT is released (rather than the modelled lkg/s) to the marine environment then the maximum deposition rate for this worst case scenario would be 0.156mg TBT /sq. m.
Scenario 1 considered the existing situation at Yam 0 Wan. The cumulative impact is likely to be great given that there are currently 5 docks operating in close proximity to one another and their discharges containing TBTs are likely to be dispersed over a similar area. Maximum deposition rates occur over a relatively wide area and therefore it is possible that on occasion all docks could be repairing TBT coated ships and for one tidal cycle (5 x 0.156) 0.78 mg TBT/sq m could be deposited. As TBT paints are increasing in popularity again due to alternative antifoulants being less effective, between the five docks it is possible that a significant number of TBT treated ships will be washed down over the period of time that TBTs persist in the environment.
Page - 4
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Ref: EP 21N3/45 II
AXT287l1J920001TC
Comments and Responses
Peak deposition rates would occur for Scenario 2 close to the dock where sediment is already contaminated with TBT (as indicated by the CES Report for EPD and preliminary data for this study.) Concentrations would therefore be greater here but the actual cumulative impact is unlikely to be so severe given that the sediment has been contaminated in this area for many years as a result of pollutants in industrial discharges and is therefore not considered to support anything but pollutant- tolerant organisms.
Under Scenario 3, maximum deposition rates occur over a greater area than for Scenario 2. Background levels around Tsing Yi were measured by CES and found to be 74 ng TBT/g. Although very little is known about toxicity of TBT in sediments, this level is probably not harmful to marine organisms based on data available from sediment toxicity studies quoted in the literature e.g. WHO (1990) and reviewed in the ElA. According to the literature, studies have indicated that the effect of TBT present at 0.1 mg/kg, was lost after 3 months. If it is assumed that the particles deposited during a wash down resulted in O.l56mg TBT/kg it could also be assumed that the impact on marine organisms could persist over a three month period. During that three month period HUD could treat up to 10 ships, all of which could be TBT treated and under this worst case the sediment could receive a total TBT loading of over 15 mg TBT Ikg. The impact would therefore worsen as TBTs would accumulate and their toxic effect would worsen given that impact is dose related. The higher the loading, the more long lasting the effect would be. It is however difficult to determine the cumulative effect given that it is very dependent upon the number of ships in the area and the number and
Page - 5
Extension to TYTL l08RP, Proposed Reclamation and Relocation of United Floating Dock, Draft EIA Report
Comments and Responses
:!!!IIII!!IIIII!!ii;i;1!!;::,I~;;III.II~lij,lllliil·Jlljl;i:i;;"llililliliilli:II:III~'il;llj~lil!llil Environmental Protection Department
Ref: EP 2/N3/45 II
3.
4.
Regarding the maximum sedimentation rate given on page 46 the value of 18mg TBT per square meter at the end of the tidal run is not correct. The model assumed a released of lkg/s of particulate and the corresponding maximum rate of sedimentation at the end of the. tidal run was 30 g/sq.m. If 5.2 mg/s of TBT was released then maximum sedimentaton rate of TBT would be 0.156mg/sq.m. or equivalent to 2.2 flm/sq.m. Please review your assessment base on this revised figures;
Please note that the figure 4.3 referred to in Table 5.2 is missing. Could the Consultants offer an explanation for the apparent reduction in TBT in water during the operational phase of Station 3. What is the detection limit and accuracy of the test;
AXT287/1/92000ITC
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frequency of ships serviced by HUD which use TBT antifoulant.
Approval to relocate the dock would reduce the impact of two docks in Yam 0 Wan, thus having considerable benefits to Yam 0 Wan and surrounding area. It is also recognised that the cumulative impact of TBTs from United and the Whampoa, other shipyards and the Ma Wan Fairway, used by a considerable number of ships would be significant over a period of time. Relocation would enable HUD to collect the washwater and filter it to remove a significant proportion of the TBTs. The modelling scenarios do not consider the fact that relocation will facilitate the enormous benefits of collecting and filtering the washwater - the effect of the reduction in TBT release due to this measure will be vastly more significant than the effect of the location itself.
Figures have been reviewed as suggested (see above) and will be incorporated into the final text. Values are considerably lower based on these revisions but the comparison between the two sites remains the same.
The figuie will be incorporated into the report - it is a general figure to show the sampling locations based on the crucifix pattern adopted.
The analytical procedure for TBT analysis is set out in detail in the EIA report (Appendix 6). The laboratory used is that used by CES for EPD's study (to ensure that results 'wo'uld be comparable) and is the
Page - 6
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Extension to TYTL l08RP, Proposed Reclamation and Relocation of United Floating Dock, Draft EIA Report
Comments and Responses
Ref: EP 21N3/45 II
5.
6.
Quoting form newspaper (Eastern Express 1996) should be avoided and the details should be checked directly with Marine Research Centre Hong Kong;
Page 3 I, line 9 - amend the phase to " the plume has the potential to affect waters used as feeding grounds for the dolphins and the Ma Wan FCZ."
C. Section 5.3
I. although housekeeping measures are being implemented, elevation of TBT concentration in the sediments at Yam 0 wan is still observed. The report should comment on the effectiveness of these measures, which should then be reviewed to see if there is room for further improvement. The idea of collecting and treating the wash water prior to discharge to the marine water should significantly reduce the quality of TBT released to the marine water and is strongly supported. We will be pleased to meet with the proponent to further discuss the wash water collection and treatment scheme in
AXT287 J IJ92000lTC
only laboratory we have been able to find which can produce consistent results. The apparent reduction in TBT in water during the operational monitoring compared to baseline levels was unlikely to be due to experimental error and all samples were treated in the same way. It is more likely that a paint chip was present in the baseline sample, released from other docks operating in the area. TBT concentrations in water are very dependant upon activities going on at the actual time the sample was taken. The EM&A Manual will therefore include a requirement for these factors to be recorded as they can help with data interpretation.
Noted. This statement will be verified in the final report.
. Noted, this will be amended in the final report
The report' will comment on the effectiveness of these measures although, as stated above, it cannot be quantified. Although housekeeping measures reduce TBT inputs, process waters have been analysed and results (received 10/6196) indicate that wash water contains extremely elevated levels of TBT. The final report will include this data which was taken hourly over a washdown period in January and February 1996 and ranges from 18,000 ng SnlL to 1,600,000 ng SnlL. The high levels again may have been a result of paint chips in the sample and may not be representative of the
Page -7
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Extension to TYTL I08RP, Proposed Reclamation and Relocation of United Floating Dock, Draft EIA Report
Comments and Responses
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Extension to TYTL l08RP, Proposed Reclamation and Relocation of United Floating Dock, Draft EIA Report
Comments and Responses
Ref: EP 21N3/45 II
E. Section 7.2
I.
2.
The number of sampling stations, their locations, the parameters to be tested for, the sampling frequencies and timing etc. need to be carefully considered by the consultant when they draw up their detailed EM&A proposals based on consideration of the relevant impact hypotheses. These will obviously be tailored to answer the specific questions relevant to this study. Similarly the control level approach (e.g. use of TAT levels) needs to be specifically considered for this particular project. I expect that the consultant is fully aware of all this - however I am concerned that the general nature of the text and its reference to a 'typical' approach may later be misinterpreted as having been agreed with EPD. I therefore suggest that - all of the first paragraph after the first sentence (Le. "Based on these conditions ..... mid ebb and mid flood." ) be deleted or at least reworded.
Please also note that I believe that it would be appropriate to simplifY the proposed 3 tier "TAT" approach with a simpler 2 tier approach focused on a 'Compliance Level' based on the WQO or other agreed standard and an intermediate 'Action Level' to flag up concern and initiate action to prevent breach of the Compliance Level. For information, as a general rule, I would not favour setting a 'Compliance' or 'Target' level based on 3 consecutive high readings. I would prefer a single exceedance of a level defined to take account of the WQO and conditions at non impacted control or reference stations. However, this issue can really only be determined at any given site following analysis of the baseline conditions to
This paragraph will be reworded. It is intended that a clearly defined monitoring and audit programme for both the construction and operational phases of the development is devised in the form of a stand alone EM&A manual. The EM&A work will address all of the key issues identified in the report. At this stage only general recommendations could be made given that some data (TBT analytical results) from the sediment surveys and the EM&A work on United is still awaited.
Noted, comments will be addressed when the EM&A manual is prepared. The report will, in the interim, be amended to incorporate these comments.
AXT287 J\J92000\TC Page - 9
Extension to TYTL 108RP, Proposed Reclamation and Relocation of United Floating Dock, Draft EIA Report
Comments and Responses
Environmental Protection Department
Ref: EP 21N3/45 II
3.
4.
understand the background 'noise' and local variability.
It will probably be preferable to have 2 control stations to represent conditions upstream and downstream of the site. Baseline monitoring will be required to confirm that these stations are representative of conditions at the site in the absence of works activity.
Minor typo. - 'Table 10.1' in the last sentence should read Table 7.1
F. Section 7.3
I. We shall provide comments on Section 7.3 separately.
District Lands Officer I Kwai Tsing
Ref: (146) in DLO/KT 87IKTLT/82 IV
(i) Para. 2.3.1
The construction period shall not commence unless the grant of extension area to HUD is finalised. The grant is withheld for the time being pending the amendment of the statutory zoning plan which in turn depends on the outcome of the EIA and TIA. Therefore the construction phase would cover a longer time span than the II-month period counting from the gazetting of reclamation.
(ii) Para. 2.3.6
As at the present time, the processing of the grant of extension area to HUD
AXT287J1J920001TC
Noted. Baseline monitoring will be undertaken in the event that the project is allowed to proceed.
Agreed, this will be amended in the final report.
Noted. See later comment and response
Noted.
The requirement for a TIA was waived by the Transport Department as it was concluded that the proposed project would have no traffic impacts. Relevant correspondence is attached as Appendix 7 of the EIA report.
If necessary the dock will be relocated after the 1997 typhoon season as land
Page - 10
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Comments and Responses
:;Iii,::11l~I!!1I:~I::;;llilllll/lllllillli:II!f~~!:~~~1illiljll'111ii'II:I!'!111:~fliiili!l!illllllllliliillil District Lands Officer I Kwai Tsing
Ref: (146) in DLOIKT 87/KTLT/82 IV
is merely at a preliminary stage. It is not mentioned in the Report whether the relocation of floating dock will depend on the land grant. If it is crucial to make land available for the relocation, the dock may not be moved before the typhoon season.
Marine Officer I Tsuen Wan
Ref: (2) in PAIS 909/109/14(7)
(a) para 2.3.5
For importing sand from PRC, Works Branch Technical Circular No. 10/95 or its latest edition should be followed and Marine Department should be consulted prior to finalising the filling method. A copy of the Circular is enclosed.
(b) para 2.3.6
Both DLO/KT and CElTS, CEO should prepare to accept to leave the anchors/sinkers in situ after the removal of the FID in future as the anchoring arrangements may render the recovery of the same very difficult.
(c) para 4.3
Impact of Relocation Phase on p.23 should read 4.4 instead of 4.3. Penn iss ion to tow the Floating Dock "United" to its new position must be sought from Marine Department in advance.
AXT287111920001TC
has to be available for mooring before the dock is relocated.
Noted. This infonnation will be included in the final report.
It is proposed that United's anchors be moved from Yam 0 wan to Tsing Yi for cost reasons. As these have only been in place for a year they will be very easy to move. However the old anchors from the Tsing Yi dock, previously moored at HUD's land based facility, will be left in place as they would be very difficult to move.
Agreed. This will be amended accordingly.
Noted. The project proponent intends to liaise closely with the marine department in order to find a suitable time and get permission for relocating the
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Extension to TYTL I08RP, Proposed Reclamation and Relocation of United Floating Dock, Draft EIA Report
Comments and Responses
;:!!:I 11III1I 111111·1·1111::I:I:IIIII!llll II 1 II! 1111111 illi:·!I!II!!!!I!I!!!:I!!I!!II!!III!!l'!·ll!I!III:I!llll!!!! Marine Officer / Tsuen Wan
Ref: (2) in PAIS 909/109/14(7)
(d)
(e)
HUD is responsible to apply for the issue of Notice to Mariners/Marine Department Notice for the project.
the height restriction for the dock to pass underneath the Tsing Ma Bridge is 53 metres.
AXT287l1J92000lTC
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dock.
Noted
Noted
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Extension to TYTL l08RP, Proposed Reclamation and Relocation of United Floating Dock, Draft EIA Report
Comments and Responses
Environmental Protection Department
Ref: EP 72/R5/8 III
(I) Section 7.3
AFD
Further to my previous comments on the draft report of the Supplementary EIA, I have one more comment on Section 7.3. It is considered that at least one more round of water and sediment monitoring at the Tsing Yi site should be carried out before the dock is relocated. This will serve to provide some baseline data (albeit limited) to facilitate identification of trends following commencement of operation.
AF DVL 10/3 PI. 17
I have no comment on the Draft EIA report
AXT28711192000lTC
Noted and agreed. Full details of additional monitoring will be incorporated into the EM&A manual and your comment will be addressed in the interim in the final EIA report
Noted
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Extension to TYTL l08RP, Proposed Reclamation and Relocation of United Floating Dock, Draft EIA Report
Comments and Responses
Ref: EP 21N3/45 II
1. Cover Page
a.
b.
The title should be "Extension to TYTL 108RP, Proposed Reclamation and Relocation of United Floating Dock, Tsing Yi".
To avoid confusion, the word "Supplementary" should be omitted.
2. Section 2.3.8
a.
b.
c.
d.
What are the number and size of the anchorage blocks?
Any rockfill on top of the existing anchorage blocks?
Would removal of the anchorage blocks causing environmental impact?
Any treatment to the pockets in Yam 0 after removal of the anchorage?
3. Section 2.4.2
AXT287/1/92000ITC
Noted. This will be amended in the final report
Noted, this will be amended in the final report
There are 26 anchor blocks each with a dry weight of 150 tonnes. They are a wedge shape 5m wide, 4.8 m long, 3.5m high at the back and 2m at the front. 20-22 of these docks will be recovered from the existing location.
Anchor pockets will be excavated, the anchor block put in place and then the pockets will be backfilled with granular material either rockfill or sand.
Removal of the blocks from Yam 0 Wan is not anticpated to cause an impact as the blocks have only been in place for just over a year and are unlikely to be covered by a significant depth of sediment. Minimal sediment disturbance is therefore expected. Loss of TBTs from this sediment will be relatively small, especially compared to concentrations of TBT released during a washdown operation on the dock. Sediment concentrations at Yam 0 are up to 3 orders of magnitude smaller than process water concentrations.
No treatment of the pockets has been proposed, the pockets at Yam 0 Wan will be left to fill in naturally.
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Extension to TYTL l08RP, Proposed Reclamation and Relocation of United Floating Dock, Draft EIA Report
Comments and Responses
a. The word "supplementary" in line 3 should be deleted.
4. Section 3.1.2
Include a scale in the figure for easy reading.
5. Section 3.2.2
a.
b.
Paragraph 2 - can the consultants confirm that the TBT results will be available for the final report and explain how these results will affect the ElA findings.
Any test, e.g. Elutriate test, to determine the likely impact of the dispersion of heavy metals during dredging of the sea mud.
AXT287 J IJ92000lTC
Noted, this will be amended
Agreed, the scale is 1 :50 000
Samples were sent to CSIRO labs in Australia in February and March. We were advised that the waitng time for results was three months. We would anticipate that at least the data for the grab samples will be available in time for the final report and hopefully all of the data. The results will provide useful information on existing sediment quality which will be used to qualify statements in the report which have been based on assumptions such as potential release of TBTs during dredging and cumulative impacts. It is not anticipated that the results will affect any of the key findings in the ErA as preliminary data was available at the time of writing and historical data was also available.
Although elutriate tests were not discussed in the report, some limited elutriate tests can be undertaken although generally metals are not readily soluble as they tend to be strongly adsorbed onto the fine fraction of the sediment. This can be explored in more detail during the preparation of the EM&A manual.
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Extension to TYTL l08RP, Proposed Reclamation and Relocation of United Floating Dock, Draft EIA Report
Comments and Responses
c. What can be concluded about the baseline condition of the seabed in respect to TBT? Poor or just good enough?
6. Section 4.3.1
AXT287 III 92000lTC
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As discussed above, baseline data for TBTs is still awaited but some preliminary data and historical data were available at the time of writing the report. It can be concluded that the sediment has a history of TBT contamination. Although the levels recorded by CES (1994) were over 1000 ng TBT/g, these are not excessive but they are elevated above typical background levels for Hong Kong. In terms of whether the material is "poor" or "good enough" it depends on what the comment is referring to. If this comment is referring to its use as a habitat then it is very likely that some of the more tolerant marine organisms would persist at these concentrations, depending on the presence of other contaminants. There is very little information on toxicity of TBTs in sediment and whereas concentrations found in the sediment may not have acute effects they may have long term chronic impacts on marine biota.
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Extension to TYTL I08RP, Proposed Reclamation and Relocation of United Floating Dock, Draft EIA Report
Comments and Responses
How significant the short term impacts on the gazetted beaches between Sham Tseng and Ting Kau would be due to the sediment dispersion?
It is anticipated that there will be no significant impact on the beaches themselves. The bathing water may be effected slighlty by the release of suspended solids and associated contaminants. Following previous comments by the EPD, it is proposed that a silt curtain is used whilst dredging the contaminated surface muds to minimise these impacts. Metals are not readily soluble and any TBT released into the. water column in the aqueous phase would have minimal short term impact on water quality as it has such a short half life. Concentrations of TBT reaching bathing waters would probably be negligible in terms of impact on bathers.
There is the potential for increased suspended solids throughout the 9 month period that dredging and reclamation takes place but the majority of sediment dispersed would not affect the bathing water (as indicated by the plume dispersion modelling). At the very worst, the effects are only likely to be visual in terms of impacts on bathers, but as waters in this area are currently unsuitable for bathing due to sewage discharges and high E.coli counts this is not considered significant.
AX1287/1/92000ITC Page - 17
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Environmental
AXIS Environmental Consultants Ltd.
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