1.1 On the 18th April 2001, Highways Department of the Government of the Hong Kong Special Administrative Region appointed Mouchel Asia Ltd, under Agreement No. CE 13/2001, to undertake the Improvement to Tung Chung Road between Lung Tseng Tau and Cheung Sha Investigation and Preliminary Design Assignment (the project).
1.2 The purpose of the Project is to improve the existing sub-standard Tung Chung Road, and thereby provide an improved roadway for connecting north and south Lantau. The improved road will be operated as a closed road in a similar manner to the existing road to prevent vehicles from the rest of Hong Kong, without Lantau Closed Road (LCR) permits, from entering South Lantau. Subject to further analysis, the current Tung Chung Road Prohibited Zone (TCRPZ) permit system might also require retention with appropriate modification to manage traffic on the improved road and tightly control its growth.
1.3 The residents in South Lantau, through the auspices of the Islands District Council, have requested that the road be constructed as a matter of urgency. Based upon the wishes of the local residents, alternative modes of transport, such as cable car or direct ferry services, between North and South Lantau would not suffice.
2. Route Description
2.1 The improved road will comprise a two-lane two-way rural road, with gradients as steep as 15%, about 6.2km long between Lung Tseng Tau and Cheung Sha. No climbing lane has been provided in the road in order to minimise the footprint of the works and therefore, minimise the environmental impacts of the project, especially on the Country Park. The proposed road improvement commences at Lung Tseng Tau, and climbs up Tung Chung Valley along the route of the existing road as far as Tai Tung Shan Service Reservoir. South of the reservoir, the proposed road veers east from the existing route and crosses the small plateau at the head of the valley, before rejoining the existing route at the crest at Pak Kung Au. South of the crest, the new road again veers east from the existing route, and traverses the hillsides around the southern flanks of Sunset Peak, before crossing the catchwater and connecting with South Lantau Road to the east of Cheung Sha Sheung Tsuen.
2.2 Roadside bus laybys and taxi layby facilities are provided near the new junction of Tung Chung Road and South Lantau Road, together with a U-turn facility for vehicles travelling along Tung Chung Road.
3. Route Option Selection and Refinement
3.1 The proposed road is situated within an overall rural area, with the surrounding land comprising country parks, open space and agricultural activities, with some villages present at either end. The landscape along the route alignment contains many elements of outstanding natural beauty, including wooded hillsides, ridges lines of the Lantau and Sunset peaks and riverine valleys. Ecologically, the area is distinguished by the presence of key habitats and species, including a fresh water marsh at Fong Yuen, woodland, clean natural streams and species of conservation interest including the rare fish the Beijiang Thick-lipped Barb and the Romer’s Tree Frog. This overall rural nature and minimised human disturbance, with the exception of the existing Tung Chung Road, is the key characteristic of the existing environmental conditions of the study area.
3.2 Maintaining these existing environmental conditions, as far as practicable, has been a major objective during the selection of a preferred route and design of the selected alignment.
3.3 The preferred alignment for the improved Tung Chung Road is shown in Figure 1. This alignment has been selected after a comprehensive option assessment process which provided an evaluation and comparison of 4 northern alignment options and 4 southern alignment option combinations within the Tai Tung Shan – Cheung Sha corridor, the environmental implications of each alternative being a key consideration. The main environmental advantages of the selected alignment over the other options include:
C shortest overland route between Tung Chung and South Lantau Road, with gentle bends and no tight loop-bends;
C least amount of bridgeworks, earthworks and retaining walls, resulting in least amount of “muck shifting” and surplus excavated material;
C least potential to impact Tung Chung Stream and Cheung Sha Stream (alignment avoids Cheung Sha Stream as far as possible);
C least ecological impacts;
C least landscape and visual impacts for overland route;
C least impacts on the Country Park for overland route; and
C least construction cost and shortest construction programme.
3.4 The avoidance and minimisation of environmental impacts has been a key element through the progressive design of the selected alignment. The current preferred route has been designed in order to reach an alignment which can be stated as representing the optimum route after balancing all relevant factors within the engineering and topographical constraints.
3.5 The main characteristics of the alignment which have been designed to minimise the environmental effects of the road include:
C alignment widened on-line as far as possible to minimise habitat loss and also on eastern side of the existing Tung Chung Road to avoid crossing over the high ecological value Tung Chung Stream;
C haul road specified along the same alignment as the main route as far as practicable to reduce the extent of temporary habitat loss;
C alignment designed on bridge structure where appropriate and with the use of retaining walls in order to significantly reduce the extent of cut slopes required, having ecological benefits;
C alignment designed to cross all key ecologically sensitive streams on structure during both the construction and operational stages to avoid direct impacts on the aquatic environment;
C construction runoff in the northern section to be collected into a special pipeline and transported to the Wong Lung Hang nullah in Tung Chung and treated via sedimentation tanks prior to discharge. This will avoid discharge into the northern streams which are tributaries of the highly sensitive Tung Chung stream. In the south, all run-off collected and treated using sedimentation tanks and oil interceptors prior to discharge to protect the streams and the water gathering grounds;
C special pipe also designed to carry road runoff to either end of the alignment to avoid discharge into any stream course during the operational phase; and
C permanent drainage system designed to avoid direct impacts on Fong Yuen Marsh and the channelised section of Tung Chung stream which is proposed to be upgraded.
4. Environmental Impact Assessment
4.1 The Project is a designated project under Section A.1 of Schedule 2 of the Environmental Impact Assessment Ordinance (EIAO). As such the statutory procedures under the EIAO need to be followed and an environmental permit is required prior to the commencement of construction. Thus, as part of this assignment, an Environmental Impact Assessment (EIA) is required to assess the potential impacts of the construction and operation of the Project.
4.2 The assessment of construction related impacts have included: air quality, noise, water quality, construction waste, ecology, landscape and visual and hazard to life. The assessment of impacts during the operation of the project have included: air quality, noise, water quality, ecology, landscape and visual, hazard to life and heritage impacts.
4.3 The Remaining Development in Tung Chung and Tai Ho Comprehensive Feasibility Study has proposed development north of the Tung Chung Valley which could be affected by the operation of the improved Tung Chung Road. Thus, for the purposes of this report, the effects on this development together with the cumulative effects of the two projects have been assessed. In addition, potential operational air and noise impacts at proposed future sensitive receivers on the sale sites in Cheung Sha have also been assessed.
5. Key Findings of the Eia
5.1 In total, eight different environmental parameters have been evaluated as part of the EIA and the impacts associated with each, as a result of the implementation of the project, predicted. Where necessary, mitigation measures have been recommended to ameliorate any impacts. The eight environmental parameters covered by the assessment are:
C air quality;
C water quality;
C waste management;
C landscape and visual;
C hazard; and
C cultural heritage.
5.2 The project would have no effect on some parameters. The hazard assessment has predicted that, overall, the risk on the road from the Cheung Sha Water Treatment Works will be low and acceptable. In respect of operational air quality, the results of the modelling show that air quality will comply with the Air Quality Objectives. For both, no mitigation measures are required.
5.3 Construction phase dust impacts can be reduced to acceptable levels with the implementation of suitable measures. A series of waste management measures to control the sorting, storage, handling, transportation and disposal of all forms of waste that may arise from the project have been determined and no adverse impacts are predicted if these measures are instigated. All the recommended measures are practicable and can be implemented. Construction noise levels can also be reduced to acceptable levels with the use of mitigation measures. In the region of 44 dwellings will be protected by the measures proposed.
5.4 The heritage impact assessment revealed the presence of former agricultural terraces in Cheung Sha and the three test pits conducted to the east of Tung Chung Road all contained historical material from the Qing dynasty. Based upon the distance of the finds from the alignment in Cheung Sha and the fact that the material found in Tung Chung does not represent a significant archaeological deposit, no mitigation measures are required.
5.5 While no direct impacts on the 23 historical buildings and structures identified have been predicted, the road will result in impacts of a visual nature but with the distance from the development providing a sufficient buffer zone during the construction phase for most of these structures. in varying degrees of indirect impact on some buildings. Thus, mitigation for a shrine in Lung Tseng Tau in the form of a protective barrier during the construction phase and the mitigation for the Fong Yuen nunnery in the form of retaining the existing woodland buffer and planting of foliage along the cycle path in the vicinity of the nunneryin order to maintain the existing environment have been recommended.
5.6 The key environmental issues concerning the project, however, relate to operational noise, landscape and visual impacts, water quality and ecology.
5.7 Without mitigation, the noise modelling has concluded that a number of sensitive receivers would be subject to operational noise levels in excess of the 70 dB(A) limit. A full range of mitigation options have been considered for the protection of these receivers.
5.8 Reflective barriers, with an aggregate length of about 127m and ranging in heights from 1.5m to 4.5m in Tung Chung have been proposed in Lung Tseng Tau. Based upon these recommended mitigation measures, all operational noise levels at properties affected by the project can be reduced to acceptable levels. Approximately 10 dwellings will be protected by these barriers in the Tung Chung area.
5.9 In addition, a landscaped earth bund, together with a 4m non building area is proposed at the future sale sites in Cheung Sha to protect the future sensitive receivers from noise impacts from the road.
5.10 The use of retaining wall and use of structures where appropriate along the alignment has reduced the degree of slope works and in addition, the road will be widened on-line as far as possible, thereby, minimising the landscape and visual impacts of the improved road. Mitigation measures to minimise the extent of the remaining impacts include:
C protection and retention of existing vegetation;
C transplanting of trees where appropriate;
C protection and retention of existing natural rocky outcrops, slope profiles, vegetation, landscape features;
C sensitive architectural and chromatic treatment of new highway structures including bridges, retaining walls and noise barriers;
C advance planting/visual screening; and
C sensitively designed site hoarding in public areas.
5.11 In addition, extensive compensatory planting of about 25ha is proposed along the alignment. It is intended that the planting will be able to recompense for the woodland and shrubland lost and to help re-establish the landscape pattern and reduce the visual impact of the road.
5.12 The project will result in some landscape and visual impacts which are predicted to remain after construction of the project despite the mitigation measures. However, the residual impacts generated by the bridge structures and noise barriers are considered acceptable within the overall benefits of the scheme.
5.13 The study area contains numerous streams which are of high ecological value, including the Tung Chung Stream and the Cheung Sha Stream which have been shown to contain aquatic species of conservation interest. The area is also located within a water gathering ground. Based upon the need to protect these streams from direct and indirect impacts, the selected road alignment is proposed to be widened on-line from Tung Chung up to the Tai Tung Shan Service Reservoir (the remaining part of the road will be largely off-line) so as to minimise earthworks and run-off potential and also the existing road will be widened on the east side where practiacble, such that during construction, the existing road can be used as a buffer zone to help prevent any pollutants from running into Tung Chung Stream. Also the selected alignment is the furthest from the Cheung Sha stream.
5.14 However, given the importance of the streams in the study area and the water gathering grounds, a range of mitigation measures has been proposed to protect the aquatic resources in the study area during both the construction and operation phases. During the construction phase, streams of high ecological importance have been crossed on structure in order to avoid impacts and the haul road, where it goes off-line, will also cross the streams on temporary bridges with spans at least twice the width of the stream.
5.15 In order to protect the Tung Chung and Cheung Sha Streams and tributaries from water borne sediments and pollutants from the construction site, a drainage system has been devised to avoid / minimise water quality impacts as far as possible. For the northern section of the new road, it is proposed that the operational drainage system be constructed ahead of the main roadworks such that it may be used to discharge the construction site runoff, thus avoid discharging construction site runoff into the streams all together. The discharge outfall for the northern section’s drainage system will be located in the Wong Lung Hang nullah near Ha Ling Pei in Tung Chung and all discharge will be treated via a sedimentation tank in order to minimise impact on Tung Chung Bay and the seagrass bed at San Tau SSSI. South of the crest, it is proposed to use a series of peripheral surface channels to encase sections of the works site to intercept and divert the surface runoff from the hinterland and the construction site. All site run-off will be treated by a series of sedimentation tanks prior to discharge into adjacent streams. Oil interceptors will also be used above the catchwater to further protect the water gathering grounds.
5.16 The key aspects of the proposed temporary drainage system which will be adopted to ensure the protection of the water quality in the inland streams, Tung Chung Bay and Pui O Wan during construction are as follows:
C system designed to have no discharge of site run-off into Tung Chung Stream;
C northern temporary drainage system will avoid discharge into any streams;
C system in the southern area divided into small sub-catchments to enhance control and minimise impacts;
C all run-off treated via a sedimentation tank prior to discharge either into streams in southern area or marine environment;
C oil interceptors used above catchwater to protect water gathering grounds;
C all parts of system will be regularly cleaned and maintained;
C hinterland runoff separated to protect from contamination; and
C system must be operational before the start of the permanent works.
5.17 Based upon the inclusion of these measures, the risk of adverse impacts to water quality during the construction phase has been reduced to a negligible level.
5.18 In respect of operational water quality impacts, contaminants in the road surface runoff are expected to be limited and, thus, impacts on the water quality of the streams are expected to be negligible. Notwithstanding, a specially designed carrier pipe along the length of the road will collect and transport all road drainage to either end of the alignment prior to discharge into the Wong Lung Hang nullah in Tung Chung and Pui O Wan. Thus, operational discharge into all streams along the route, and thus the water gathering grounds, has been avoided.
5.19 Once discharged though an outfall at Tung Chung or Pui O Wan, the road runoff would be rapidly diluted within a few tens of metres from the discharge point. In Tung Chung, the peak road runoff only amounts to about 1% of the total peak natural runoff. This value is further reduced when the dilution in the marine environment is taken into account, with the runoff from the road being equivalent to about 1% to 2.5% of the tidal volume depending upon the particular tide, based upon a 1:50 year storm. Similar, levels of contribution and dilution would be expected for the southern section of the road and the discharge into Pui O Wan. Thus, any road runoff into the bays at either end of the alignment would not be expected to result in a significant increase in the concentration of the water quality parameters of interest and will not result in a significant increase in the existing pollutant load to Tung Chung Bay or Pui O Wan.
5.20 The study area contains many key ecological resources. While the alignment has been designed, as far as practicable, to minimise the impacts on these habitats and species. For example, habitat loss has been minimised by restricting the footprint of the works and widening the road on-line as far as possible. In addition, impacts on key ecological streams have been avoided by the road crossing over these on structure and the Fong Yuen marsh has also been avoided by careful design of the permanent drainage system. However, some impacts will occur and some of the key habitats and species of concern which may be affected to varying degrees if mitigation is not applied include:
C secondary woodland along the alignment;
C streams along the route;
C shrub Pavetta hongkongensis, orchids Acampe rigida and Liparis viridiflora and tree Artocarpus hypargyreus; and
C habitats of amphibians and reptiles along the route including the Romer’s Tree Frog.
5.21 Approximately 14.5 ha of land will be affected permanently by the project which will include approximately 6.5ha loss of tall shrubland, 2.25ha of secondary woodland and 5ha of plantation woodland. Impacts on the habitats and the species have been predicted as ranging from insignificant to moderate if mitigation is not applied. A summary of the mitigation and enhancement measures recommended to minimise these impacts include:
C control of site run-off to protect ecology of water courses, particularly important for the Tung Chung Stream and the Cheung Sha Stream;
C minimisation of working areas during construction to reduce habitat damage;
C transplantation of the shrub Pavetta hongkongensis, orchids Acampe rigida and Liparis viridiflora and tree Artocarpus hypargyreus;
C special design of new culverts and culvert inlet/outlets for key streams;
C translocation of Hong Kong Newt, Lesser Spiny Frog and Romer’s Tree Frog from key streams;
C scheduling of works in key streams to avoid the period April to June which is the key breeding period for fish, amphibians and odonates;
C translocation of Romer’s Tree Frog between Lung Tseng Tau and Shek Mun Kap;
C provision of water filled pots as habitats for the Romer's Tree Frog between Lung Tseng Tau and Shek Mun Kap;
C translocation of isolated population of Beijiang Thick-lipped Barb to tributary of Tung Chung Stream;
C provision of slope surfaces at step channels for aquatic fauna to move up and down stream at existing bridges;
C provision of escape routes from drainage channels for amphibians;
C provision of wildlife tunnels for faunal transfer;
C compensatory planting of about 25ha to mitigate for vegetation loss; and
C reinstatement of land temporarily required during construction.
5.22 The proposed mitigation measures are considered adequate overall to fully mitigate all identified impacts. However, moderate residual impacts in the short term may occur as a result of the planted woodland not immediately compensating for the function of the mature woodland lost but this would reduce to minor and then insignificant impacts in the longer term as the woodland matures. Minor residual impacts associated with the barrier effect of the new road will also occur. All residual impacts are considered acceptable.
6. Cumulative Assessment
6.1 There is only one key interface with the proposed improved Tung Chung Road, situated at the northern end of its alignment, namely the proposed development in Tung Chung and Tai Ho. The development in Tung Chung is being assessed under the Remaining Development in Tung Chung and Tai Ho Comprehensive Feasibility Study (CFS) currently being conducted by the Territory Development Department. The development proposals of relevance to this study involve the development of the Tung Chung Valley.
6.2 The assessment of cumulative impacts includes air quality, noise, water quality, waste, ecological factors and landscape and visual impacts during both the construction and operational phases as appropriate.
6.3 The assessment has concluded that few cumulative impacts will occur based upon the implementation of the two projects. Sufficient mitigation measures to reduce any impacts to within acceptable levels have been recommended by both the CFS and the improved Tung Chung Road and additional mitigation measures are not considered to be required.
6.4 Cumulative noise impacts are possible when permanent noise barrier construction in Tung Chung for the Tung Chung Road is on-going in conjunction with either road works or site development for the Tung Chung Valley project. Cumulative impacts can be avoided by the careful scheduling of the works which would prevent noisy equipment working simultaneously.
6.5 Impacts on a proposed future school in the Tung Chung Valley from road traffic noise is predicted. Therefore, a landscaped earth bund has been proposed between the road and the school site and this is sufficient to reduce predicted noise levels to within the criteria.
7. Environmental Monitoring and Audit
7.1 In accordance with the EIA, EM&A procedures are required during the design, construction and operational phases of the project implementation. The EM&A works during the design phase shall comprise an iterative audit process of specific design elements. The drainage system and specifications for certain ecological and landscape mitigation measures proposed by the EIA will be required to be designed during the design phase of the project.
7.2 During the construction and operational phases, the EM&A requirements are divided into environmental monitoring and/or project auditing in the form of site inspection and supervision. EM&A for dust, noise and water quality during the construction phase is recommended in order to ensure all proposed mitigation measures are implemented and effective. All three of these parameters will also be subject to audit through site supervision.
7.3 Site supervision and procedures audit will be required during the construction phase to ensure the proper handling, storage, transportation and disposal of the various waste arisings from the project. Audit of the implementation of the design elements and mitigation measures to avoid ecological, landscape and visual and heritage impacts have also been recommended by the EIA, and thus, monitoring in the form of regular site inspections shall also be required to ensure mitigation measures are being implemented and are effective. EM&A for both ecology and landscape and visual resources will extend through the construction phase and into the operational phase to ensure planting and replanting have been effective.
7.4 Operational noise monitoring shall be undertaken in months 6 and 12 during the first year of the operation of the project to assess the effectiveness of the direct noise mitigation measures recommended by the EIA.
8. Overall Conclusions
8.1 The design of the proposed improved road has been optimised to minimise the extent and magnitude of environmental impacts, particularly the loss of habitat by minimising the footprint of the works as far as possible. Also, retaining walls have been used to minimise the extent of the cut slopes and bridges have been used to traverse the key ecologically sensitive streams and key habitats such as the Fong Yuen Marsh have been avoided.
8.2 Where, the implementation of the new road will result in some impacts, a comprehensive range of mitigation measures has been recommended to reduce these impacts to acceptable levels. Apart from the mitigation of direct impacts, it is worth noting that some of these measures, will not only mitigate impacts, but will also enhance the existing environmental conditions as follows:
C the incorporation of wildlife tunnels under the at-grade sections of road;
C sensitive design of culverts and culvert inlets and outlets to allow fish and other aquatic faunal access;
C provision of escape ramps in drainage channels for amphibians;
C provision of water filled pots for the Romer’s Tree Frog to breed in; and
C the relocation of key floral and faunal species.
8.3 In addition, the proposed remedial works to the existing slopes using bio-engineering techniques (ie, hydroseeding instead of spray applied concrete) will enhance the existing slopes, resulting in areas of higher landscape value and after completion of the road, the existing overhead electrical cables and many proposed utilities can be put underground in the new and obsolete road sections.
8.4 Furthermore, the proposed special permanent drainage system will avoid carriageway runoff from being discharged into both the Tung Chung and Cheung Sha streams and also the water gathering grounds. This will be an improvement on the existing conditions, whereby carriageway runoff is discharged directly into the small streams, watercourses and hillsides directly below the existing road.
8.5 Overall, the environmental impacts predicted for all environmental parameters can be reduced to acceptable levels with the implementation of the recommended mitigation measures. Low residual impacts on habitats are predicted based upon the fact that not all habitat loss can be mitigated in the short term. Residual impacts caused by the barrier effect of the road are expected but these will be minor in light of the recommendation to construct wildlife tunnels at at-grade sections of the road.
8.6 Residual landscape and visual residual impacts will occur but the landscape proposals will substantially mitigate for the impacts in the long term.
8.7 All the residual impacts of the project are considered acceptable within the overall scope and benefits of the project.