7                     ECOLOGICAL IMPACT

7.1               Introduction

7.1.1          The following section presents the results of an assessment of potential ecological impacts resulting from the Project.  Literature review and field surveys were undertaken to identify ecological sensitive receivers, and the ecological importance of habitats/species potentially affected by proposed works was evaluated.  The scale of possible ecological impacts resulting from the proposed works was assessed, and necessary mitigation measures were identified.  Cumulative impacts resulting from this and other Projects in the area were assessed.  Residual ecological impacts were assessed, and ecological monitoring and audit requirements were identified.

7.2                Environmental Legislation, Policies, Plans, Standards and Criteria

7.2.1          Guidelines, standards, documents and HKSAR Government ordinances and regulations listed in the following sections were referred to during the course of the ecological impact assessment.

7.2.2          The Forests and Countryside Ordinance (Cap. 96) prohibits felling, cutting, burning or destroying of trees and growing plants in forests and plantations on Government land.   Related subsidiary Regulations prohibit the selling or possession of listed restricted and protected plant species.  The list of protected species in Hong Kong which comes under the Forestry Regulations was last amended on 11 June 1993 under the Forestry (Amendment) Regulation 1993 made under Section 3 of the Forests and Countryside Ordinance.

7.2.3          The Wild Animals Protection Ordinance (Cap. 170) provides protection for protected wild animals against hunting, trapping and wilful disturbance, whilst their nests and eggs are protected from injury, destruction and removal.  The Second Schedule of the Ordinance which lists all the animals protected was last revised in June 1992.

7.2.4          Chapter 10 of the Hong Kong Planning Standards and Guidelines (HKPSG) covers planning considerations relevant to conservation.  This chapter details the principles of conservation, the conservation of natural landscape and habitats, historic buildings, archaeological sites and other antiquities.  It also describes enforcement issues.  The appendices list the legislation and administrative controls for conservation, other conservation related measures in Hong Kong and Governmental departments involved in conservation.

7.2.5          Environmental Impact Assessment Ordinance (Cap. 499) Technical Memorandum – Annex 16 set out the general approach and methodology for assessment of ecological impacts arising from a project or proposal, to allow a complete and objective identification, prediction and evaluation of the potential ecological impacts.  Annex 8 recommends the criteria that can be used for evaluating habitat and ecological impact.

7.2.6          Town Planning Ordinance (Cap. 131) provides for the designation of coastal protection areas, Sites of Special Scientific Interest (SSSIs), Conservation Area (CA), Country Park (CP), Green Belt (GB) or other specific uses that promote conservation or protection of the environment.  The authority responsible for administering the Town Planning Ordinance is the Town Planning Board.


7.2.7          The IUCN Red List of Threatened Species provides taxonomic, conservation status and distribution information on taxa that have been globally evaluated using the IUCN Red List Categories and Criteria.  This system is designed to determine the relative risk of extinction, and the main purpose is to catalogue and highlight those taxa that are facing a higher risk of global extinction (i.e. those listed as Critically Endangered, Endangered and Vulnerable).  The IUCN Red List also includes information on taxa that are categorized as Extinct or Extinct in the Wild; on taxa that cannot be evaluated because of insufficient information (i.e. are Data Deficient); and on taxa that are either close to meeting the threatened thresholds or that would be threatened were it not for an ongoing taxon-specific conservation programme (i.e. are Near Threatened).

7.3               Assessment Methodology

Scope of Ecological Assessment

7.3.1          The study area for the terrestrial ecological environment includes all areas within 500m from the site boundary of the land based works or the area likely to be impacted by the Project.  For aquatic ecological environment, the study area is within 300m from the site boundary or the area likely to be impacted by the Project.  While the Project is land based only, and the nearest marine environment is the Castle Peak Bay, which is located about 400m away from the site boundary, the Project is unlikely to cause potential impact to the marine environment.

7.3.2          Existing literature documenting the ecology of the proposed Study Area was reviewed.  A terrestrial scoping survey was conducted in August 2007.

7.3.3          Habitat survey was undertaken to determine the types, sizes and locations of habitats in the Study Area.  The habitat survey was conducted via desktop review of aerial photographs, base-maps, other relevant maps and plans followed by site visits.  Representative photographs of habitat types were taken.

7.3.4          Vegetation survey was conducted via direct observation and recording of the presence and dominance of species in the representative habitats within the Study Area.

7.3.5          Fauna including avifauna, herpetofauna, mammal and terrestrial insect (butterfly and odonate) were surveyed in the Study Area.  The survey was conducted by direct observation, listening for calling animals, searching potential micro-habitats and searching for signs of animal activity (e.g. tracks, burrows).  Species present and relative abundance of species in different habitat types were recorded.  The location of species of conservation interest was also recorded.

7.4               Description of the Environment

7.4.1          The Works Area is located along Tuen Mun Road from San Hui Sitting-out Area to Kam Fei Garden (Figure 7.1A, 7.1B & 7.1C).

7.4.2          The proposed Works Area is located within developed area, a habitat of low ecological value, which is comprised of residential area, sports centre, town hall, car park, market, shopping mall and schools.

7.4.3          Within the Study Area, there are agricultural areas at Wong Ka Wai, Leung Tin Village and Tseng Tau Tsuen; shrubland/woodland at Tai Lam Country Park; Egretry next to river channel and San Hui Playground; Tuen Mun Town Park with man-made pond and waterfall; plantation woodland at Sam Shing Hui; Tuen Mun River Channel; Tuen Mun container terminal and Castle Peak Beach.


Areas of Conservation Interest

Egretry

7.4.4          An active egretry of 0.13 ha is located between San Hui Playground and the eastern bank of Tuen Mun River Channel, which is approximately 270m away from the northern end of the main works boundary.  As the egretry is located near urban areas, it mainly comprises of a few plantation species, including Albizia sp., Chinese Banyan (Ficus microcarpa) and Chinese Hackberry (Celtis sinensis).  Little Egret is locally very common, and the large, secure population in Hong Kong is considered to be of regional significance by Fellowes et al. (2002).

Tai Lam Country Park

7.4.5          The eastern side of the Study Area is bounded by approximately 67 ha of Tai Lam Country Park.  The Park occupies 5,370 ha of forested land and was designated in 1979.

7.4.6          The flora species at Tai Lam Country Park are diverse. The most common species include Taiwan Acacia (Acacia confusa), Brisbane Box (Lophostemon confertus), Chinese Red Pine (Pinus massoniana), Slash Pine (Pinus elliottii), Swamp Mahogany (Eucalyptus robusta) and Paper-Bark Tree (Melaleuca leucadendron).  Oak, Machilus species, Ivy Tree (Schefflera octophylla), and Castanopsis (Castanopsis fissa) are also abundant.

Habitat Type and Vegetation

Table 7.1          Habitat Type within the Study Area

Habitat Type within the Study Area

Size

Woodland

5 ha

Shrubland

67 ha

Inactive / Active agricultural area

2 ha

Plantation woodland

5 ha

Town park

12 ha

Developed area / Village

583 ha

Watercourse

Streams: 4.6 km / River channel: 12 ha

 

Woodland

7.4.7          A dense woodland of 5 ha was found on a slope surrounding the Tuen Mun East Fresh Water Service Reservoir.  There was also an undergrowth of shrub.  Flora species recorded include Elephant's Ear (Macaranga tanarius), Lebbek Tree (Albizia lebbek), Desmos (Desmos chinensis), Aporusa (Aporusa chinensis) and Microcos (Microcos paniculata). Species recorded were all common and widespread in Hong Kong.


Shrubland

7.4.8          A shrubland habitat of 67 ha was located at the east of the Study Area at Tai Lam Country Park.  Vegetation species in this habitat include Taiwan Acacia (Acacia confusa), Brisbane Box (Lophostemon confertus), Chinese Red Pine (Pinus massoniana), Slash Pine (Pinus elliottii), Swamp Mahogany (Eucalyptus robusta) and Paper-bark Tree (Melaleuca leucadendron).  The species present were all common and widespread in Hong Kong.

Inactive / Active Agricultural Area

7.4.9          Agricultural areas (2 ha) were found in patches around villages including Wong Ka Wai, Leung Tin Village and Tseng Tau Tsuen.  Species found in this habitat include Papaya (Carica papaya), Banana (Musa paradisiaca), Jackfruit (Artocarpus heterophyllus), Longan (Dimocarpus longan), Wampi (Clausena lansium) and species in the Araceae family.  They are all common species in the agricultural areas in Hong Kong.

Plantation Woodland

7.4.10      With a size of 5 ha, the plantation woodland was located on a small hill at Sam Shing Hui.  It was made up of species such as Bambusa species, Bauhinia species, Chinese Fan Palm (Livistona chinensis), Flamboyant (Delonix regia) and Morning Glory (Ipomoea cairica).  The species recorded were all common and widespread.  No species of conservation importance were identified.

Town Park

7.4.11      Tuen Mun Town Park covered 12 ha of land and has more than 2,000 trees and 100,000 shrubs of about 200 various species.  It also has a man-made lake and other recreational facilities.  It was a developed, artificially created and managed plantation habitat with constant human disturbances.

Developed Area / Village

7.4.12      Developed area and villages occupy 583 ha of land, which made up the majority of the Study Area.  Vegetation was scarce at the Works Area and was usually in the form of roadside and amenity plantation.  The fifty-nine plant species identified around and among the Works Area are common and widespread in Hong Kong. No protected species were found.

7.4.13      There were villages at Wong Ka Wai, Leung Tin Village and Tseng Tau Tsuen.  This habitat was composed of village housing interspersed with patches of vegetation.  Vegetation was mainly comprised of fruit tree species as discussed in Section 7.4.9 (Agricultural Area), and some ornamental plants such as Hoop Pine (Araucaria cunninghamii), Lawson's Cypress (Chamaecyparis lawsoniana), and White Jade Orchid Tree (Michelia alba) were identified.

Watercourse

7.4.14      The major watercourse recorded within the Study Area was the Tuen Mun River Channel.  It flowed from north to south and led the collected sewerage and water into the Tuen Mun Typhoon Shelter.  The channel had moderate flow and the water appeared to be of poor to moderate quality.


7.4.15      Tuen Mun River Channel (12ha) was channelised with concrete banks and did not support riparian vegetation.  The embankment was vegetated with planted mature trees and weed.  Typical plant species recorded include tree species such as Chinese Banyan (Ficus microcarpa), Elephant’s Ear (Macaranga tanarius) and White Popinac (Leucaena leucocephala); shrub species such as Lantana (Lantana camara); herb species such as Chinese Silvergrass (Miscanthus sinensis), Redtop (Rhynchelytrum repens), Triste Gahnia (Gahnia tristis) and Bidens alba.  Creeping Fig (Ficus pumila) and Gairo Morning Glory (Ipomoea cairica) were also occasionally found.

7.4.16      Some streams / rivers (approximately 4.6 km in total) were also found flowing from Tai Lam Country Park to the Study Area, where most of them are natural and of good water quality.

Fauna

Avifauna

7.4.17      In a recent survey, birds recorded around the Study Area were mainly common urban birds: Chinese Bulbul (Pycnonotus sinensis), Eurasian Tree Sparrow (Passer montanus), Japanese White-eye (Zosterops japonicus), Magpie Robin (Copsychus saularis), Red-whiskered Bulbul (Pycnonotus jocosus) and Spotted Dove (Streptopelia chinensis).  Barn Swallow (Hirundo rustica) was found at flight over a nearby woodland habitat.   All birds are protected under the Wild Animals Protection Ordinance (Cap.170).

7.4.18      During our field survey, ten individuals of Little Egret (Egretta garzetta), a species of conservation importance, were found foraging along the embankment of Tuen Mun River Channel, where one was spotted on a Lebbek Tree (Albizia lebbekk).  No nesting or breeding activities within the egretry were observed during the survey.  Little Egret is locally very common, and the large, secure population in Hong Kong is considered to be of regional significance by Fellowes et al. (2002).  As the egretry locates near to the urban areas, it mainly comprises of few plantation species, including Albizia sp., Chinese Banyan (Ficus microcarpa) and Chinese Hackberry (Celtis sinensis).

7.4.19      According to the Hong Kong Biodiversity (2007) and HWBWS (2005). 27 and 16 nests of Little Egret (Egretta garzetta) were recorded nesting at the Tuen Mun Egretry in 2005 and 2006 respectively. 

Herpetofauna and Mammals

7.4.20      During the recent survey, no herpetofauna or mammal was recorded in the Study Area.

7.4.21      Starting from 2002, territory-wide surveys have been conducted by the Herpetofauna Working Groups of AFCD (Chan et al. 2005).  Referring to these previous surveys, two species of amphibians were recorded in the Study Area, including Brown Tree Frog (Polypedates megacephalus) and Gunther’s Frog (Rana guentheri).  Both amphibian species recorded are very common and widely distributed in Hong Kong.  No rare or protected herpetofaunal species were recorded in the Study Area.

7.4.22      Amphibians including Green Cascade Frog (Rana livida), Asiatic Painted Frog (Kaloula pulchra pulchra) and Hong Kong Cascade Frog (Amolops hongkongensis); reptiles such as White-spotted Slug Snake (Pareas margaritophorus), Bicoloured Stream Snake (Opisthotropis lateralis) and Changeable Lizard (Calotes versicolor), have been previously recorded in Tai Lam Country Park.

7.4.23      According to Chan and Shek (2006), a roost of Short-nosed Fruit Bat (Cynopterus sphinx) was recorded near the Study Area.  It is a species of conservation importance and is protected under the Wild Animals Protection Ordinance (Cap. 170).

7.4.24      It has been reported that Chinese Pangolin (Manis pentadactyla) and Chinese Leopard Cat (Felis bengalensis) were recorded within the Tai Lam Country Park, who are both listed in Wild Animals Protection Ordinance (Cap. 170); Red Muntjac (Muntiacus muntjac) is another species that has been recorded in the Country Park.

Terrestrial Invertebrate (Butterfly and Dragonfly)

7.4.25      During the recent field survey, no terrestrial invertebrate was recorded in the Assessment Area.

7.4.26      According to the “EIA-142/2007 – Widening of Tuen Mun Road at Tsing Tin Interchange” Project, which is 340m from this Project, five butterfly species were recorded in the Assessment Area.  Three butterfly species, including Common Mormon (Papilio polytes), Great Mormon (Papilio memnon) and Indian Cabbage White (Pieris canidia) were recorded in the village habitat; Common Grass Yellow (Eurema hecabe) was recorded in developed areas, whilst Red-base Jezebel (Delias pasithoe) was found in both village and developed areas in the Study Area.  All recorded species are common and widespread in Hong Kong.  No rare or protected species was recorded.

7.5               Ecological value

7.5.1          In accordance with the EIAO TM Annex 8 criteria, the ecological importance of recorded habitats has been evaluated in Table 7.2 below.

Table 7.2          Ecological Value of Woodland and Shrubland in the Study Area

Criteria

Woodland

Shrubland

Naturalness

Mostly natural

Mostly natural

Size

5 ha – Woodland habitat is small in size

67 ha – Shrubland habitat is moderate in size

Diversity

Moderate diversity and complexity

Moderate diversity and complexity

Rarity

No rare species were recorded during survey

No rare species were recorded during survey

Recreatability

Moderate. It would take more than 30 years mature.

Moderate. It would take several years to mature.

Fragmentation

Fragmented as surrounded by urban development

Not fragmented as it was part of the Tai Lam Country Park

Ecological linkage

A small section of woodland was connected to Tai Lam Country Park

This habitat was part of the Tai Lam Country Park

Potential Value

Moderate

Moderate

Nursery Ground

No record of significant nursery or breeding ground was found in the surveys

No record of significant nursery or breeding ground was found in the surveys

Age

Over 30 years

Over 10 years

Abundance/ Richness of Wildlife

Low to moderate

Moderate

Ecological Value

Moderate

Moderate

 

Table 7.3          Ecological Value of Plantation Woodland and Inactive/Active Agricultural Area in the Study Area

Criteria

Plantation Woodland

Active/Inactive Agricultural Area

Naturalness

Artificially created

Artificially created

Size

5 ha – plantation woodland habitat is small in size

2 ha – agricultural area is small in size

Diversity

Low to moderate

Low

Rarity

No rare species were recorded during survey

No rare species were recorded during survey

Recreatability

High. It would take several years to mature.

High

Fragmentation

Fragmented as it only covered the small hill and was surrounded by urban area.

Highly fragmented as they were areas in small patches

Ecological linkage

No significant linkage was identified

Low to moderate. Some are partially linked to Tai Lam Country Park.

Potential Value

Low to moderate

Low

Nursery Ground

No record of significant nursery or breeding ground was found in the survey

No record of significant nursery or breeding ground was found in the survey

Age

Over 20

N/A

Abundance/ Richness of Wildlife

Low

Low

Ecological Value

Low

Low

 


Table 7.4          Ecological Value of Town Park and Developed Area in the Study Area

Criteria

Town Park

Developed Area

Naturalness

Artificially created

Artificially created

Size

12 ha – town park is small in size

583 ha – developed area is large in size

Diversity

Low to moderate

Low

Rarity

No rare species were recorded during survey

No rare species were recorded during survey

Recreatability

High

High

Fragmentation

N/A

N/A

Ecological linkage

Habitat is not structurally or functionally linked to any high ecological value resources

Habitat is structurally linked to Tai Lam Country Park

Potential Value

Low

Low

Nursery Ground

No record of significant nursery or breeding ground was found in the survey

No record of significant nursery or breeding ground was found in the survey

Age

Over 20 years

N/A

Abundance/ Richness of Wildlife

Low to moderate

Low

Ecological Value

Low to moderate

Low

 


Table 7.5          Ecological Value of Watercourse in the Study Area

Criteria

Watercourse

Naturalness

Tuen Mun River Channel was man-made and channelised.

The streams from Tai Lam Country Park were mostly natural.

Size

Total length of the streams is 4.6 km

The section of river channel covers 12 ha of the Study Area

Diversity

Low

Rarity

An active egretry of 0.13ha was identified immediately next to the Tuen Mun River channel. One faunal species of conservation interest, Little Egret (Egretta garzetta), was recorded during survey

Recreatability

Man-made channel: High

Natural stream: Moderate

Fragmentation

Not fragmented

Ecological linkage

Man-made channel: not structurally or functionally linked to any high ecological value resources

Natural stream: upper reaches flowed though Tai Lam Country Park

Potential Value

Low

Nursery Ground

Watercourse supports a small population of Little Egret

Age

N/A

Abundance/ Richness of Wildlife

Low

Ecological Value

Man-made channel – Low

Natural stream - Low to moderate

 


7.5.2          In accordance with the EIAO TM Annex 8 criteria, species of conservation interest are evaluated in Table 7.6 below.

Table 7.6          Evaluation of Fauna Species of Conservation Interest within the Study Area

Common Name

Scientific Name

Conservation Status[1]

Protection Status

Distribution

Avifauna

Little Egret

Egretta garzetta

PRC (RC)

Listed in Cap 170[2]

Common

Note:

[1]    PRC – Potential Regional Concern. RC – Regional Concern (Habitat loss/damage in Hong Kong would pose significant threat to regional survival).  Letters in parentheses indicate that assessment of status is based on restrictedness of breeding and/or roosting sites rather than general occurrence.  Refer to Fellowes et al. (2002) for further explanation of status.

[2]     Protected under the Wild Animals Protection Ordinance (Cap.170)

 

7.6               Identification of Impacts

7.6.1          Potential ecological impacts resulted from construction and operation phase activities of the proposed works have been identified, and outlined following the EIAO TM Annex 16 guidelines; the impacts were evaluated based on criteria in EIAO TM Annex 8.

Construction Phase

Direct Impacts

7.6.2          No direct impact on ecologically important habitats would be resulted from the proposed works.  All of the proposed works would be conducted within the developed area along Tuen Mun Road and would take up approximately 12 ha of land.  The main work site would be located at the section between San Hui Sitting-out Area and Kam Fei Garden.  The two isolated sites located at the north of the work site have been proposed for small scale road marking work, and the ones located to the east and west are for junction improvement works.

7.6.3          The existing roadside plantation would be directly affected by the road widening and the construction of flyover.  Tree removal/relocation would be required to give way to the construction works.  Most species recorded were locally common roadside plantation, including Acacia confusa, Bauhinia blakeana, Melaleuca leucadendron and Delonix regia.  No rare or protected species were recorded at the proposed Works Area.

Indirect Impacts

7.6.4          Noise generated during road widening and flyover construction would cause disturbance to the nearby wildlife.  Habitats that are most likely to be affected by the construction noise include the woodland near Tuen Mun East Fresh Water Service Reservoir, the plantation woodland at Sam Shing Hui, a small section of Tai Lam Country Park at the southern end of the Works Area, and the egretry which is 270m away from the northern end of the Works Area.


7.6.5          Construction dust generated during piling, excavating, filling, backfilling and materials handling would affect the surrounding vegetation.  Mini pile foundation works for noise barriers, wind erosion from the site and general construction works would also affect the surrounding environment.  Construction dust could cover leaves and lead to reduction in photosynthesis rate, abrasion and stomata blockage, thus reducing the quality of habitat.

7.6.6          An increase in human activities could cause indirect impacts to habitats and their associated fauna.  The presence of human and their disturbance (e.g. noise, waste) may cause the avoidance of habitats by fauna and reduction in wildlife density within the habitat.

7.6.7          Site runoff and drainage from the proposed Works Area would enter Tuen Mun River Channel causing degradation of water quality if uncontrolled, hence affecting the habitat users including aquatic fauna and Little Egret, a species of conservation importance, found at the egretry.

7.6.8          Waste generated during construction would temporarily occupy the nearby work sites.  The accumulation of waste would cause visual disturbance to wildlife, thus degrading the quality of their habitat.

Operation Phase

Direct Impacts

7.6.9          No potential direct impacts on ecologically important habitats have been identified during operation.

7.6.10      Transparent noise barrier is a potential hazard to birds, as birds are not always sensitive to their presence due to the transparency, which is preferred by the public as concrete ones would block view and light.  Direct collision sometimes occurs as birds are unable to recognise them as physical barrier and could result in bird mortality.  Vertical barriers, cantilever barriers and enclosure (full or semi) are proposed on most section of Tuen Mun Road.  The distance between the nearest proposed barrier and egretry is 310m.

Indirect Impacts

7.6.11      The proposed noise barrier would greatly reduce the noise from the busy traffic along the Works Area.  The reduced level of noise would decrease the level of disturbance to the wildlife at nearby habitats.

7.7               Evaluation of Ecological Impacts

7.7.1          Potential ecological impacts arised from the Project have been evaluated according to Table 1 of Annex 8 of the EIAO TM. The evaluation are summarised in the tables below.

Table 7.7          Overall Impact Evaluation of Woodland and Shrubland

Evaluation Criteria

Woodland

Shrubland

Habitat quality

Moderate

Moderate

Species

No species of conservation interest were recorded in this habitat during the surveys

No species of conservation interest were recorded in this habitat during the surveys

Size/Abundance

No direct impact to this habitat

No direct impact to this habitat

Duration

Indirect impact would be short term during construction

Indirect impact would be short term during construction

Reversibility

Indirect impact is reversible

Indirect impact is reversible

Magnitude

Small

Small

Overall Impact Conclusion

Low

Low

 

Table 7.8          Overall Impact Evaluation of Plantation Woodland and Inactive/Active Agricultural Area

Evaluation Criteria

Plantation Woodland

Inactive / Active Agricultural Area

Habitat quality

Low

Low

Species

No species of conservation interest were recorded in this habitat during the surveys

No species of conservation interest were recorded in this habitat during the surveys

Size/Abundance

No direct impact to this habitat

No direct impact to this habitat

Duration

Indirect impact would be short term during construction

Indirect impact would be short term during construction

Reversibility

Indirect impact would be reversible

Indirect impact would be reversible

Magnitude

Small

Small

Overall Impact Conclusion

Low

Low

 

Table 7.9          Overall Impact Evaluation of Town Park and Developed Area / Village

Evaluation Criteria

Town Park

Developed Area / Village

Habitat quality

Low to moderate

Low

Species

No species of conservation interest were recorded in this habitat during the surveys

No species of conservation interest were recorded in this habitat during the surveys

Size/Abundance

No direct impact to this habitat

Approximately 10 ha of developed area would be occupied by the Works Area. Removal of roadside plantation would be required

Duration

Indirect impact would be short term during construction

Direct impact would be permanent. Indirect impacts would be temporary.

Reversibility

Indirect impact would be reversible

Direct impacts would be non-reversible. Tree removed could be transplanted at different locations. Indirect impacts would be reversible.

Magnitude

Small

Moderate

Overall Impact Conclusion

Low

Low

 

Table 7.10        Overall Impact Evaluation of Watercourse

Evaluation Criteria

Watercourse

Habitat quality

Man-made channel – Low

Natural stream – Low to moderate

Species

One species of conservation interest, Little Egret (Egretta garzetta), was recorded in this habitat during the survey

Size/Abundance

No direct impact to this habitat

Duration

Indirect impact would be short term during construction

Reversibility

Indirect impact would be reversible

Magnitude

Small

Overall Impact Conclusion

Low

 

Construction Phase Impacts Evaluation

Impacts on habitats

7.7.2          No direct impact on ecologically important habitats would be resulted from the proposed works.  Works would be conducted in the developed area which is used for schools, residential area, shopping mall and sports ground.  Due to the heavy traffic flow and high level of human disturbance, the developed area within the Study Area is not expected to function as nursery or breeding ground for wildlife.  The Works Area was not structurally or functionally linked to any habitats of high ecological value.  The impacts from the loss of developed area are therefore considered to be low.


Impacts on vegetation

7.7.3          The roadside plantation of common species would be directly affected by the Project.  Tree removal would be required for the construction works.  Such impact could be mitigated by transplanting and compensatory planting after the construction works.  As the species recorded are common and widespread in Hong Kong, the impact of vegetation loss is therefore considered to be low.

7.7.4          Dust generated during construction could block plant surface and their stomata, thus affecting the rate of photosynthesis.  The decrease in quality of plants and habitats would indirectly affect the associated wildlife.  Such degradation in habitat and associated wildlife could be controlled via site mitigation and dust reduction methods, the impacts arised from construction dust is therefore considered to be acceptable.

Impacts from disturbance

7.7.5          Indirect impacts to habitats and associated fauna around the proposed Works Area, especially the plantation woodland right next to the southern end of the proposed Works Area, would be affected by an increase in human activities/disturbance during the construction phase.  Such impacts could arise from noise generated by machines during road widening, road paving, construction of noise barrier, and general increase in human activity.  With the implementation of effective mitigation measures, construction phase disturbance to the nearby ecologically important habitats and the inhabitating wildlife could be minimised.  Moreover, wildlife and plant species within the Study Area have adapted to high level of pollution and urban disturbances.  The impacts of disturbance are therefore considered to be low.

Impacts from Waste Dumping

7.7.6          Impacts resulted from improper dumping of construction material/waste and deposition of dust on vegetation within and near to the Works Areas can be avoided and minimised to acceptable levels through the implementation of standard good site practice.

Impacts on Water Quality

7.7.7          Uncontrolled site runoff would carry pollutants and sediments into Tuen Mun River Channel and eventually into the Tuen Mun Typhoon Shelter.  Mitigation measures could be implemented to control construction site runoff and drainage from the proposed Works Area, and to prevent runoff and polluted drainage water from entering the river channel and the sea.  With the implementation of adequate site drainage and provision of sediment removal facilities, it is therefore considered that impacts on water quality are acceptable.

Impacts on Fauna

7.7.8          Little Egret, a bird species of conservation interest, was recorded at the egretry at, and along the Tuen Mun River Channel.  In Hong Kong, Little Egret is a species adapted to pollution and disturbance.  Impacts that could affect the livelihood of egrets include construction noise, increase in the presence of human and site runoff. Considering that the Tuen Mun Egretry is located in highly urbanised areas with high level of noise from the nearby existing traffic flow, and Little Egret utilising the Tuen Mun River Channel and the egretry for nesting and breeding could tolerate a certain level of disturbance, the impact on Little Egret is considered as low. With the implementation of appropriate mitigation measures, such as temporary noise barrier, careful scheduling of works, and implementing good site practice, the noise disturbance to the Little Egret utilising the egretry for breeding and nesting activities during the construction phase would be minimized.   

7.7.9          Aquatic invertebrate and fish at Tuen Mun River Channel could be affected by site runoff and polluted drainage water from work sites.  With the implementation of adequate construction site drainage and provision of sediment removal facilities, potential impact of unacceptable water quality at the River Channel should not arise.  The potential impacts to the aquatic invertebrate and fish are considered to be low.

Operation Phase Impacts Evaluation

7.7.10      No substantial direct and indirect ecological impacts are expected to add on to the existing impacts caused by the present operation of Tuen Mun Road.

7.7.11      The invisibility of noise barrier to all birds must be mitigated.  Falcon sticker is effective in making transparent barrier more visible to birds, thus preventing bird collision.  Other practices include the use of tinted materials, embedded opaque stripes and superimposed patterns of thin opaque stripes, are also effective in reducing the chance of bird collision.  With the combination of these measures, bird collision could be minimised.  The impact of noise barrier on birds is therefore considered to be low.

7.7.12      The Tuen Mun Egretry is not expected to be significantly affected during operation, as Little Egret is adapted to human disturbance and the egretry has already been exposed to the daily heavy traffic at Tuen Mun Road.  Noise impact on the egretry is considered to be low as permanent noise barriers have been proposed to be constructed.  Nesting activities are not expected to be affected during operation.

7.8               Cumulative Impacts

7.8.1          The “EIA-142/2007 – Widening of Tuen Mun Road at Tsing Tin Interchange” Project, hereinafter to be referred to as “Project A”.  The location of the Works Area of Project A is 340m to the north of the main Works Area of this Project.  Project A would involve the provision of an additional interchange connecting Tuen Mun Road and Castle Peak Road near Sam Shing Estate, and widening of Tuen Mun Road at Tsing Tin Interchange from a dual two-lane to dual three-lane arrangement.  Project A commenced in June 2008 for completion in 2010, which should concurrent with this Project which is scheduled for commencement in end 2009.

7.8.2          Project A is not expected to have direct impacts on high ecological value habitats.  However, construction phase activities are considered to have potential cumulative impacts from air and noise pollution on the habitats at the northern section of the Study Area.  As the proposed works areas of the two projects are 340m away from each other, and the proposed construction periods have a short overlapping time, cumulative impacts resulting from the two projects are expected to have temporary and minor ecological impact.

7.8.3          For the potential cumulative impacts on the Tuen Mun Egretry, the overlapping time for Project A and the current Project is short, and that impacts such as noise and site runoff could be controlled by effective mitigation measures, cumulative impacts resulting from the two projects are expected to have temporary and minor ecological impact.

7.9               Mitigation Measures

7.9.1          Following EIAO-TM Annex 16 guidelines, mitigation measures are discussed in this section to avoid, minimise and compensate for identified ecological impacts.


Avoid

7.9.2          Construction activities should be confined to developed areas of low ecological value.  There should be no direct impact on other habitats within the Study Area.

Minimise

7.9.3          Noise mitigation measures, including installation of noise-emitting construction plant away from egretry, careful scheduling of noisy works with high disturbance impact to avoid breeding season of ardeid species (i.e. mid March to August) to prevent impacts on nesting activities of Little Egret, operation of well-maintained machinery, and use of noise reduction facilities could be implemented to mitigate noise impacts arised from construction activities such as road widening and road paving.  Temporary noise barrier should also be used to reduce the level of noise during construction.  Noise impact would be minimised during operation phase as permanent noise barrier has been proposed to be constructed.  The use of low noise road surfacing could also reduce the level of noise during operation.  Such measures could minimise disturbance to habitats, including the egretry, within and adjacent to the proposed Works Area.  Detailed mitigation of noise impact is shown in the Noise Impact section (Section 3) in this EIA report.

7.9.4          In order to minimise the impact of construction dust to the vegetation and associated wildlife within and around the proposed Works Area, practical measures such as regular watering, complete coverage of dusty material storage piles, and the use of minimum practical height for dropping excavated material should be implemented.  Detailed mitigation for construction dust impact is shown in Air Quality Impact section (Section 4) in this EIA report.

7.9.5          Standard good site practice measures should be implemented and should include:

              Placement of equipment in designated Works Areas within the existing disturbed land.

              Construction activities should be restricted to the proposed Works Area.

              The proposed Works Area should be reinstated immediately after completion of the works.

              Open burning on proposed works site is illegal, and will be strictly enforced.

              Waste skips should be provided to collect general refuse and construction wastes, which should be disposed regularly and properly off-site.

              Soil contaminated by fuel leaked from construction plants should be removed and treated.

7.9.6          Mitigation measures should be implemented to prevent and minimise the indirect impacts to the nearby Tuen Mun River Channel by controlling construction site runoff and drainage from the proposed Works Area.  Site runoff could be directed towards regularly cleaned and maintained sand traps, silt traps and where appropriate, oil/grease separators to minimise risk of sedimentation and pollution to the river channel.  Debris and rubbish generated on-site should be collected, handled and disposed properly. 

7.9.7          In order to prevent and minimise the chance of bird collision during operation phase, falcon sticker, tinted materials, embedded opaque stripes and superimposed patterns of thin opaque stripes are methods that could be used during the design of noise barrier.


Compensate

7.9.8          Compensatory planting is recommended as the current roadside plantation must be removed to give way to the works.  Species of choice should be composed of similar native species and the felling and planting ratio should be no less than 1:1 in terms of quantity.

7.10            Evaluation of Residual Impacts

7.10.1      With the proposed mitigation measures in place, no adverse residual impacts resulting from the construction and operation of TMRTCS widening works is expected.

7.11            Environmental Monitoring and Audit

7.11.1      The overall potential ecological impacts from the Project are considered to be minor.  No specific ecological monitoring programme is required.  Environmental audit is needed to ensure the ecological impacts from the construction and operation of the Project is kept within acceptable levels, and the application and mitigation measures are practical and effective.

7.12            Conclusion

7.12.1      The seven habitat types identified within the Study Area in this ecological survey include woodland, shrubland, plantation woodland, inactive/active agricultural area, town park, developed area/village and watercourse.  The identified woodland and shrubland habitats are considered to have moderate ecological value, while the other habitats are considered to have low to moderate value.

7.12.2      No direct impact on ecologically important habitats would be resulted from the proposed works, which would take up 12 ha of developed area.  The proposed construction works would only occur within the developed area, which is of low ecological value and is comprised of a section of Tuen Mun Road from San Hui Sitting-out Area to Kam Fai Garden.  The developed area supports no floral and faunal species of conservation importance.  The impact on habitat loss is considered to be low.

7.12.3      Little Egret (Egretta garzetta), a species of conservation interest, has adopted to tolerate a certain level of pollution and disturbance.  It was recorded at the egretry and along the embankment of Tuen Mun River Channel within the Study Area.  Construction and operation of the Project are not expected to have significant impact on the egretry and bird population with the implementation of the proposed mitigation measures. 

7.12.4      The impact of loss of vegetation through removal of roadside plantation of common species within the proposed Works Area is not considered to be ecologically significant.  The loss could be compensated by compensatory planting or transplantation.

7.12.5      Bird collision with the proposed construction of permanent noise barrier could result in bird mortality.  With the combination of the suggested measures for the design of noise barrier, bird collision due to the noise barrier would be minimized.

7.12.6      Considering the small scale of proposed construction works, highly disturbed nature of the Study Area, and with the proposed mitigation measures in place, including noise mitigation measures and good site practice, no adverse ecological impacts from the construction and operation of the Project is expected.

7.13            References

AFCD (2007). http://www.afcd.gov.hk/english/country/cou_vis/cou_vis_cou/cou_vis_cou_tl/cou_vis_cou_tl.html (Last visited in August 2007)

Chan, S.K.F., Cheung, K.S., Ho, C.Y., Lam, F.N., Tang, W.S., Lau, M.W.N. & Bogadek, A. (2005). A Field Guide to the Amphibians of Hong Kong. Agriculture, Fisheries and Conservation Department, Friends of the Country Parks and Cosmos Book Ltd., Hong Kong.

Chan, S.M. & Shek, C.T. (2006). Survey on the Short-nosed Fruit Bat (Cynopterus sphinx) in the Urban Areas of Hong Kong. Hong Kong Biodiversity, 11: 8-10.

Fellowes, J.R., Lau, M.W.N., Dudgeon, D., Reels, G.T., Ades, G.W.J., Carey, G.J., Chan, B.P.L., Kendrick, R.C., Lee, K.S., Leven, M.R., Wilson, K.D.P. & Yu, Y.T. (2002). Wild Animals to Watch: Terrestrial and Freshwater Fauna of Conservation Concern in Hong Kong, Memoirs of the Hong Kong Natural History Society 25: 123-159.

Highways Department (2006). Practise Notes No. BSTR/PN/003 - Revision B. Noise Barriers with Transparent Panels.

Hong Kong Bird Watching Society (HKBWS) (2005). Egretry Counts in Hong Kong, with particular reference to the Mai Po Inner Deep Bay Ramsar Site, Summer 2005 Report. AFCD.

Lee, W. H. & Wong, Y.H. (2007). Review of Egretries in Hong Kong, Hong Kong Biodiversity- Agriculture, Fisheries and Conservation Department Newsletter, 14. Agriculture, Fisheries and Conservation Department (AFCD), Hong Kong.