10.                      Conclusions and Recommendations

10.1                   Introduction

10.1.1              Environmental impact assessments for the Reclamation of Yau Tong Bay are conducted under the requirement of the Study Brief No. ESB-0010/1998.  The key environmental issues involve noise, water quality, waste management, biogas risk, land contamination and visual and landscape impacts.  Major findings and the recommendations are summarized in the following sections.

10.2                   Major findings of the Environmental Impact Assessment Study for the Reclamation of Yau Tong Bay

Reclamation Method

10.2.1              With due consideration of the environmental impacts caused by reclamation to the harbour, a more environmental friendly reclamation method and construction sequence among other possible alternatives are recommended for the proposed reclamation.  As the release of contaminants in the seabed could not be avoided during the process of dredging, and treatment and disposal of both contaminated and uncontaminated dredged marine sediment will create another environmental impacts, the reduced amount of dredging can minimize the adverse impact caused by dredging.  “Drained” reclamation method is proposed for general reclamation area in order to expedite the rate of settlement.  By this method, except the dredging of soft marine deposit for the foundation of new seawall and the proposed box culverts, which is considered essential in engineering points of view, no additional dredging of marine sediment will be required. 

10.2.2              Apart from this reclamation method, the construction sequence is carefully designed in order to minimize the adverse environmental impacts arising from reclamation.  The existing stormwater culvert will be diverted to the harbour by a temporary channel such that the discharge will not enter into the reclamation site.  The permanent seawalls, which will be built prior to the bulk filling, together with the existing seawall and the temporary diversion channel will enclose the entire reclamation site, preventing the dispersal of fill material to the harbour. 

10.2.3              In order to alleviate the acute shortage of filling capacity to minimize the need of new public dump site and to help extend the existing land fill life in Hong Kong, except the use of rockfill for the foundation of new seawall and sandfill for the drainage blanket to be overlay directly onto the marine deposit, it is recommended to maximize the use of public filling material for reclamation of Yau Tong Bay in principle.  Imported sandfill will only be used for reclamation in the case of unstable or insufficient supply of public filling material which affect the construction programme.

Noise

10.2.4              An environmental noise impact assessment on the proposed Yau Tong Bay Development Reclamation has been conducted to predict the construction noise impacts at the existing and planned noise sensitive receivers (NSRs) in the Yau Tong neighbourhood.

10.2.5              The predicted facade noise levels at the nearby NSRs will be within the construction noise criterion for domestic premises throughout the reclamation period.

10.2.6              Recommendation has been given with practicable mitigation measures to further reduce the construction work noise impact on the NSRs.

Water Quality

Assessment Criteria and Water Sensitive Receivers

10.2.7              The water quality impacts of the YTB reclamation during the construction and operation phases were assessed against the Water Quality Objective (WQO) for the Victoria Harbour Water Control Zone (VHWCZ) and the relevant standards at the salt water intakes in the YTB area.  Water sensitive receivers (WSRs) most likely to be affected are:

·       The salt water intakes of the existing and future potential reprovisioned Cha Kwo Ling Salt Water Pumping Station (CKLSPS) under Full Reclamation option;

·       The salt water intakes of the existing and reprovisioned Yau Tong Salt Water Pumping Station (YTSPS); and

·       The existing Dairy Farm Ice Factory salt water intake (DFSI).

Construction Phase Water Quality Impacts

10.2.8              Sediment plume modelling was conducted to assess the water quality impact for the different construction phases of the proposed YTB reclamation.  According to the current construction schedule, bulk filling will commence after the seawall construction and thus the plume is effectively confined in YTB.  Modelling results show that no major impact is expected in Victoria Harbour during the construction phase.

10.2.9              As a result of the dredging and filling activities for the YTB reclamation, an elevation of suspended solids in the water column was predicted at the WSRs. The works schedule was carefully programmed so that the production rate, and thus the water quality impact, is minimized.  Furthermore, appropriate mitigation measures were recommended for the YTB reclamation as follows:

·       Closed grab dredgers with silt curtain should be used for the dredging and filling of seawall foundation;

·       A silt curtain should be placed across the seawall opening during the Phase 1 and Phase 2 reclamations using bottom dumping;

·       Double layers of silt screen should be installed at the salt water intakes of the YTSPS, CKLSPS and DFSI; and

·       The filling rates of Phase 1 and Phase 2 reclamations should be limited to 10,000 m3day-1 and 6,000 m3day-1 respectively.

10.2.10          With the proposed mitigation measures fully implemented, it is anticipated that the size of the sediment plume of the YTB reclamation (Full Reclamation option) will be reduced, minimizing the impact on Victoria Harbour.  It is also expected that the SS concentration at the WSRs will satisfy the WSD tolerable limit for SS (20mgL-1) at the CKLSPS and YTSPS, and the in-house standard of 20mgL-1 for SS at the DFSI at all times.

10.2.11          Taking into account the impacts of other concurrent construction activities in Victoria Harbour, including:

·       The Western Coast Road;

·       The Tseung Kwan O New Town Intensification and Extension;

·       The Tseung Kwan O Cargo Working Area; and

·       The South East Kowloon Development;

It was found that the YTB reclamation only contributes to a minor impact on the water quality near YTB.  With the implementation of the recommended mitigation measures, the concurrent construction activities in Victoria Harbour are not expected to cause any unacceptable adverse impact to Victoria Harbour and the identified water sensitive receivers.

10.2.12          The model results indicate that temporary diversion of the YTB stormwater culvert to the existing water front, south of YTB, would have negligible impact on the water quality in Victoria Harbour and other sensitive receivers.

10.2.13          Laboratory analysis of marine sediment samples from YTB revealed that the potential release of contaminants during the dredging and surcharging works will not cause any exceedance of the UK Water Quality Standards for Coastal Surface Water, and thus, unacceptable adverse impact is not anticipated.

10.2.14          An environmental monitoring and auditing (EM&A) program is recommended to ensure that the YTB reclamation works would not cause unacceptable deterioration of water quality at the neighbouring salt water intakes and in Victoria Harbour.

Operation Phase Water Quality Impacts

10.2.15          A major concern of the YTB reclamation is the potential impact on the flow through Victoria Harbour and, in turn, the water quality.  Hydrodynamic modelling reveal that the changes in flow discharge rates through Victoria Harbour before and after the YTB reclamation would be very small and the tidal flow patterns would be similar with minor deviation near YTB.  These results indicate that the YTB reclamation is unlikely to have any noticeable effect on the tidal flow regime and hence water quality in Victoria Harbour.

10.2.16          In Full Reclamation Option, as well as the Minimised Reclamation Option, the water quality at the existing Cha Kwo Ling Salt Water Pumping Station (CKLSPS) is expected to be acceptable.  Hence, reprovisioning of the existing CKLSPS intake after Yau Tong Bay reclamation will not be required.  If it is the intention of WSD to relocate their CKLSPS, it can be relocated to the new waterfront of YTB reclamation in Full Reclamation Option.  The potential water quality impact of an emergency discharge from the Yau Tong Sewage Pumping Station on the possible future reprovisioned CKLSPS has been assessed.  The model results indicate that the depth averaged water quality in terms of BOD5, SS and ammoniacal nitrogen is expected to meet the WSD standards at the future reprovisioned CKLSPS; however, the E. coli standards will be exceeded.  The sewage plume is shown to attach to the shoreline and is buoyant at the surface with a thickness of less than 0.4m.  To avoid abstracting the sewage plume water, it is recommended that the saltwater intake should be located below -2.0 mPD.  The intake water would then be expected to comply with the WSD water quality standards.  The optimal intake configuration should be reviewed and decided at the detailed design stage if reprovisioning is required by WSD.

10.2.17          The existing YTB stormwater culvert will eventually be extended to the new water front of YTB reclamation.  The model results indicate that the polluted stormwater in the new Kwun Tong nullah and the new YTB stormwater culvert is not expected to have any major water quality impact in Victoria Harbour, as well as at both the existing and potential reprovisioned CKLSPS and YTSPS.

Waste Management

10.2.18          During the construction phase of the four proposed development options, wastes generated by construction works are likely to include general site wastes, workforce wastes, maintenance and chemical wastes, and construction and demolition material.  Chemical waste produced from the construction activities should be handled according to the Code of Practice on the Packaging, Labelling and Storage of Chemical Wastes and disposed of by a licenced contractor.  These waste arisings are not expected to generate significant waste management related impacts, provided that the recommended mitigation measures are implemented and good site practices are adhered to.

10.2.19          The drained reclamation method is recommended for YTB reclamation to minimize the volume of dredged sediments and the potential environmental impacts.  The estimated total dredged volume for the Full Reclamation option is 175,150 m3, among which 82,800 m3 are classified as Category H mud.  The total dredged volume for the Minimised Reclamation option is estimated to be 112,170 m3, with 53,270 m3 classified as Category H mud. 

10.2.20          It is considered that the potential impacts of the dredging works and associated dredged sediment disposal can be minimized provided that the recommended mitigation measures, including the procedures detailed in WBTC No. 3/2000, are implemented.  Contaminated dredged sediments will not be suitable for open sea disposal.  A sediment sampling and testing programme will be required at the design stage of the Project in accordance with the requirements of WBTC No. 3/2000.  The need for any special treatment/disposal procedures for dredged sediments will be examined in detail at the design stage, as necessary, based on the results of biological screening.  A review of possible special disposal arrangements has recommended containment of the contaminated sediments during dumping to prevent any release of material to the marine environment.  Field trials are recommended to be undertaken during the detailed design stage (using uncontaminated mud) to establish the optimum handling method.

Biogas Risk

10.2.21          Organically enriched material is planned to be left in-situ beneath the proposed YTB Full Reclamation and Minimised Reclamation options.  As methane gas could be generated under anaerobic conditions, there is a potential for this gas to be released either during construction or after development of the reclaimed area.

10.2.22          The risk of gas generation becoming a development constraint of the two proposed reclamation options for YTB has been assessed.  The predicted methane gas generation potential is not expected to pose a constraint to the development of the proposed reclamation.

10.2.23          As sensitive ‘at risk’ rooms have been identified at the proposed development for both reclamation options, it is recommended that a precautionary principle be applied.  It is recommended that gas monitoring be undertaken in the immediate post-reclamation period (prior to the commencement of construction works on the reclamation) to measure methane concentrations in the fill and to determine actual rates of methane gas emissions.  The review of the monitoring results would determine the extent and type of gas protection measures to be incorporated in the building design to prevent the ingress and/or accumulation of any methane gas emissions to potentially dangerous concentrations.  Guidelines on criteria for evaluation of the gas monitoring results and gas protection measure requirements have been identified for both the ground level and underground structures at the development.  As a further precaution, naked flames should not be permitted during construction involving drilling or excavation.

10.2.24          The proposed monitoring guidelines and other precautionary mitigation measures recommended for both reclamation options should be examined further at the detailed design stage with regard to the specific design details of individual buildings.  With the incorporation of the recommended gas protection measures in the design of the buildings together with the implementation of the recommended precautionary measures, the risk to people and property is considered to be low.

Land Contamination

10.2.25          A detailed land contamination assessment for the site has been completed. Site investigation works, including soil testing for contamination level, were conducted in accordance with an endorsed Contamination Assessment Plan (CAP).  The soil and groundwater analytical results revealed that the marine lots were partly contaminated with petroleum hydrocarbons and heavy metals.  High level of PCBs and PAH were also found in isolated locations.  Remediation methods for treating contaminated soil and groundwater were proposed in the Remediation Action Plan (RAP) and the developer should implement and complete the required remediation works to the required standard prior to commencement of any development construction works.

Visual and Landscape Impact

10.2.26          The quality of the existing landscape of Yau Tong Bay is generally poor.  The access to waterfront is blocked by the shipyards, timberyards and open storage areas, and the bay is occupied by numerous vessels and barges.

10.2.27          The construction activities will have low negative impact to the landscape resource and landscape character.  The negative impact would be further reduced if Minimised Reclamation Option is adopted.

10.2.28          The mitigation measures proposed will minimize the potential visual and landscape impact, although, the effect is limited.

10.2.29          The extent of visual impact to adjacent lots will depend on the construction programme of these lots.  In general, Yau Tong Estate Redevelopment and EHC site (Phase 1 and 2) will be completed and occupied by future resident during construction phase of the project, while resident for EHC site (Phase 3) will still not move in.

10.2.30          The construction activities will have moderate negative visual impact to the future resident of Yau Tong Estate Redevelopment, EHC site (Phase 1 and 2), and Cha Kwo Ling Kaolin Mine Site, while the impact to the industrial workers at Ko Fai Road will be low.  The visual impact to the existing resident at Sceneway Garden, Lam Tin Estate, Ping Tin Estate, Kwong Tin Estate, Hong Nga Court, Hong Pok Court, Ko Chun Court and Ko Yee Estate at mid level of Chiu Keng Wan Shan are considered as low as their views toward the site will be mostly blocked by the house blocks of Yau Tong Estate Redevelopment and Ko Chiu Road Estate Redevelopment (Phase 3 and 5) in year 2001, and EHC site development at year 2004 to 2006.

10.2.31          During the operational phase, the impact remains the same as construction phase if the flat piece of reclaimed land is allowed to leave idle.  The impact would be reduced if construction work for proposed comprehensive development are proceed continuously after completion of reclamation work, although, there will likely be some negative impact due the construction work.

10.2.32          Based on the above study, the landscape and visual impact are considered acceptable with mitigation measures for both Reclamation Options.

10.2.33          If coastal option of Western Coast is adopted, Full Reclamation Option would be carried out and the proposed elevated structure of Western Coast Road would be constructed at the reclaimed land on western side of the project site, it would form a dominent feature along the waterfront of East Kowloon.  The visual impact is considered negative.  It would be beneficial to the harbour views if the Western Coast Road is constructed on the reclaimed land directly.  If such proposal is adopted, footbridges and/or underground subways will be provided across the Western Coast Road to improve the pedestrian linkage from Yau Tong and CDA site to the waterfront.

10.2.34          The magnitude of negative impact on both landscape and visual quality due to the proposed reclamation works at operational phase would be reduced if Tunnel Option for the future Western Coast Road is adopted (i.e. Minimised Reclamation Option). It would also help to minimize the impact to the coastal line of Victoria Harbour as the proposed extent of reclamation works are reduced.

10.3                   Overall Conclusion

10.3.1              The existing Yau Tong Bay is currently characterised by industrial operations such as shipyards, timber yards, sawmills, construction materials storage, industrial building and vehicle repair workshops.  The existing environment of YTB is considered poor and is suspected to be polluted by the existing industries.  The stagnant water in the bay, together with the current industrial operations will cause nuisance to the future residents of the adjacent large-scale housing redevelopment projects when completed.  The harmful pollutants generated by the highly contaminated industry will also affect the health of existing and Yau Tong Bay future residents.

10.3.2              Additionally, the future and presently operated schools in the vicinity of Yau Tong Bay are vulnerable to noise nuisance generated by the operations on the existing marine lots.  It is foreseeable that complaints from future nearby residents against the nuisance will pose a problem and pressure for the government.

10.3.3              Reclamation of Yau Tong Bay and the subsequent development on the reclaimed land provide an opportunity to remove the existing polluting industrial operations at Yau Tong Bay.   It is undoubtedly to the benefits of everyone who lives or studies in Yau Tong for the bay to be reclaimed such that the nuisance caused by the polluting industrial operations could be removed as well.

10.3.4              The seabed of the existing Yau Tong Bay is highly contaminated by the discharge or contaminants released from the existing industrial operations of the surrounding marine lots, such as shipyards, sawmill or car repairing industry.  The odour arising from the contaminated seabed might cause nuisance to the nearby residents.  Also, consuming the polluted fishes caught at the bay would be harmful if not hazardous to health.  In order to minimise the adverse impacts of the contaminated seabed to the public and marine habitat, it is recommended to retain the contaminated marine deposit at its original position as far as possible and isolate it from the marine environment.  Concealing the contaminated Yau Tong Bay seabed by reclamation is an effective method to achieve this. 

10.3.5              The reclamation also provides an opportunity for decommissioning the existing shipyards and demolition of building structures.  This project not only relieve the pollution problems caused by the existing industries, but also provide land to achieve important community development objectives, such as provisions of schools and open space for continuous seafront promenade.

10.3.6              The present EIA study for the YTB reclamation indicated that there would be no insurmountable environmental impact arising from the reclamation works in YTB, provided that the recommended mitigation measures for the adverse impacts during the different reclamation phases are implemented.  Environmental monitoring and auditing are required to verify the efficacy of the proposed mitigation measures and to ensure that the adverse impacts are minimized and the relevant standards are complied with at all times.