8.5 Habitat Quality
8.5.1 Background
8.5.1.1 In this
section, the ecological importance of the habitats identified within the Study
Area are evaluated in accordance with criteria stipulated in Annex 8 of the
EIAO TM.
8.5.2.1 As discussed
in the foregoing Section 8.4, secondary woodland patches within the Study Area
can be differentiated into three types according to their topographic location.
Although there are differences in many ecological aspects of these patches, the
ecological value of secondary woodland as a whole is considered high. An assessment of the secondary woodland in
accordance with the criteria stated in Annex 8 of the TMEIA is provided in
Table 8.16 below.
Criteria |
Secondary
Woodland |
Naturalness |
Secondary
woodland dominated by native plant species and suffering only limited human
disturbance |
Size |
Comparatively
large in size as a whole |
Diversity |
Rich
in terms of floral diversity |
Rarity |
None
of the plant species recorded are rare in HK. Five rare faunal species were
recorded in secondary woodland,
including one of very high conservation interest and four of moderate
conservation interest |
Re-creatability |
Possible if adequate resources are available (man-power, land, finance, re-planting material) and in the absence of disturbance, but original habitat characteristics including the community composition and structural complexity may require > 20 years to establish |
Fragmentation |
Patchily distributed in Study Area. Fragmentation of patches is minimal |
Ecological
linkage |
Native
secondary woodland may provide a movement corridor for wildlife within the
Study Area and it could serve as a seed source to facilitate the succession
process in the surrounding area. Functionally linked to streams passing
through this habitat |
Potential
value |
High
potential for growth and expansion in terms of size and species diversity |
Nursery/
breeding ground |
The
protected endemic Romer’s Tree Frog was found to be breeding in this habitat
– notably at Shek Mun Kap and Lung Tseng Tau |
Age |
Relatively
old (>50 years) with respect to the size of the trees and the structural
complexity and community composition |
Abundance/
Richness of wildlife |
High,
106 species of fauna present; 5 species of conservation interest |
Ecological value |
High
|
8.5.3.1 Since the
plantation woodlands described in the foregoing Section 8.4.9, are
significantly different in terms of habitat characteristics, the ecological
evaluation will be conducted separately, with the exception of categories
pertaining to fauna. According to the Table 8.17 below, it is considered that
the mature and semi-mature plantation woodland along the Cheung Sha catchwater,
as well as around Pak Kung Au, have a moderate to high ecological value,
whereas the ecological value for other plantation woodland is moderate.
Table
8.17 Ecological Evaluation of
Plantation Woodland Within the Study Area
Criteria |
Plantation A:
along Cheung Sha catchwater |
Plantation B:
on hill-slope around Pak Kung Au |
Plantation C:
on hillslope on the east of Tung Chung Road |
Naturalness |
Man-made
habitat planted |
Man-made
habitat planted |
Man-made
habitat planted |
Size |
Relatively
large in size as a whole |
Relatively
large in size |
Relatively
large in size |
Diversity |
Rich
floral diversity |
Moderate
floral diversity |
Botanically
poor |
Rarity |
None
of the plant species recorded are rare in HK. Seven
faunal species of moderate conservation interest |
None
of the plant species recorded are rare in HK. Seven
faunal species of moderate conservation interest |
None
of the plant species recorded are rare in HK. Seven
faunal species of moderate conservation interest; one of very high
conservation interest |
Re-creatability |
Readily
re-creatable provided adequate resources are available (man-power, land,
finance, re-planting material) |
Readily
re-creatable provided adequate resources are available (man-power, land,
finance, re-planting material) |
Readily
re-creatable provided adequate resources are available (man-power, land,
finance, re-planting material) |
Fragmentation |
Moderately
fragmented |
Not
fragmented |
Not
fragmented |
Ecological
linkage |
Functionally
linked to streams passing through this habitat |
Functionally
linked to streams passing through this habitat |
Functionally
linked to streams passing through this habitat |
Potential
value |
Relatively
high given the maturity of the plantation |
Relatively
high given the location of the plantation |
Relatively
high given the location of the plantation |
Nursery/
breeding ground |
The
protected endemic Romer’s Tree Frog was found to be breeding in this habitat |
The
protected endemic Romer’s Tree Frog was found to be breeding in this habitat |
The protected endemic Romer’s Tree Frog was found to be breeding in this habitat |
Age |
Mature
plantation forest |
Relatively
young plantation forest |
Relatively
young plantation forest |
Abundance/
Richness of wildlife |
High,
100 species of fauna recorded, 4 species of conservation interest |
High,
100 species of fauna recorded, 3 species of conservation interest |
High,
101 species of fauna recorded, 1 species of conservation interest |
Ecological value |
Moderate
to high |
Moderate
to high |
Moderate
|
8.5.4.1 Since the
habitat structure and species diversity of tall shrubland within the Study Area
is complex and rich, and has a species composition comparable to secondary
woodland, the ecological value of this habitat type is considered moderate to
high. An assessment of the tall shrubland in accordance with the criteria stated
in Annex 8 of the TMEIA is provided in Table 8.18 below.
Table 8.18 Ecological Evaluation of Tall Shrubland Within the Study Area
Criteria |
Tall
Shrubland |
Naturalness |
Natural habitat |
Size |
Moderate as a whole for the Study Area |
Diversity |
Botanically diverse |
Rarity |
None of the floral species recorded was rare. Thirteen species of fauna of conservation interest were present, including two of very high conservation interest, four of high conservation interest and three of moderate conservation interest |
Re-creatability |
Readily
re-creatable provided that adequate resources are available (man-power,
land, finance, re-planting material) and in the absence of disturbance |
Fragmentation |
Fragmentation
is moderate with respect to the distribution pattern of the habitat within
the Study Area |
Ecological
linkage |
Functionally
linked to streams passing through this habitat |
Potential
value |
High
given the rich tree flora within the habitat |
Nursery/
breeding ground |
The
protected endemic Romer’s Tree Frog was found to be breeding in this
habitat, at Pak Kung Au |
Age |
Moderate
in terms of the succession pathway |
Abundance/
Richness of wildlife |
High,
113 species of fauna recorded in this habitat, 12 species of conservation
interest |
Ecological
value |
Moderate to high |
8.5.5 Shrubland-Grassland
Mosaic
8.5.5.1 Shrubland-Grassland
Mosaic is species rich and structurally complex as a whole for the mosaic, and
is considered to have a moderate ecological value (Table 8.19).
Table
8.19 Ecological Evaluation of
Shrubland-Grassland Mosaic Within the Study Area
Criteria |
Shrubland-Grassland
Mosiac |
Naturalness |
Natural
habitat but may suffer frequent disturbance (hill fire) |
Size |
Large
in size as a whole for the Study Area |
Diversity |
Botanically diverse as a whole for the habitat mosaic |
Rarity |
None of the floral species recorded was rare. Three species of avifauna of conservation interest were present |
Re-creatability |
Readily
re-creatable provided that adequate resources are available (man-power, land,
finance, re-planting material) and in the absence of disturbance |
Fragmentation |
Fragmentation
is relatively limited with respect to the distribution pattern of the habitat
within the Study Area |
Ecological
linkage |
Functionally
linked to streams passing through this habitat |
Potential
value |
Moderate
as a result of the location and the potential fire disturbance |
Nursery/
breeding ground |
No
significant breeding ground or nursery detected |
Age |
Young
in terms of the succession pathway |
Abundance/
Richness of wildlife |
Moderate,
41 species of fauna recorded in this habitat; 3 species of conservation
interest |
Ecological value |
Moderate |
8.5.6 Streams and Riparian Habitat
8.5.6.1
Riparian vegetation in the
Study Area is broadly similar to that of the surrounding habitat, comprising
secondary woodland, plantation or tall shrubland. However, stream habitats are
of particular value due to the fauna present, either utilizing the riparian
zone (terrestrial and aquatic species) or within the stream itself. Several
streams in the Study Area are seasonal, or of very low base flow, and these are of lower ecological value than
the permanent streams with reliable discharge, upon which fully aquatic fauna
are dependent. The following evaluation divides streams into two broad
categories, those with generally higher base flow supporting species of
conservation interest, and those with generally lower base flow not supporting
species of conservation interest, as summarised in Table 8.15. An evaluation of
stream and riparian habitat is presented below in Table 8.20.
Table
8.20 Ecological Evaluation of Stream
and Riparian Habitat Within the Study Area
Criteria |
Streams A (relatively
higher base flow): TC, CS, 15, 18, 19, 21, 23, 24, 25, 26, 27, 32, 35, 40,
41, 42, 43 |
Streams B (relatively lower
base flow): 1-14, 16, 17, 20, 22, 28-31, 33, 34, 36-39, 44 |
Naturalness |
Natural
habitat, pristine at higher elevations, generally more disturbed at lower
elevations |
Natural
habitat, pristine at higher elevations, generally more disturbed at lower
elevations |
Size |
Small
in size as a whole for the Study Area; generally exceeding 500m in length
from headwaters to coast. Relatively moderate to high base flow |
Small
in size as a whole for the Study Area; several less than 500m in length due
to interception by catchwater. Relatively low to moderate baseflow |
Diversity |
Botanically
diverse as a whole for the habitat mosaic |
Botanically
diverse as a whole for the habitat mosaic |
Rarity |
No
rare floral species recorded. Numerous rare/endangered species of fauna were
present across these streams as a whole, including eight of very high
conservation interest, eight of high conservation interest and four of
moderate conservation interest |
Chinese
cobra present at stream 9 although not an aquatic species |
Re-creatability |
Re-creatable
provided that works conducted in ecologically-sensitive manner and original
flow not diverted or polluted, and in the absence of disturbance |
Readily
re-creatable provided that works conducted in ecologically-sensitive manner
and original flow not diverted or polluted, and in the absence of disturbance |
Fragmentation |
Low
– moderate. Generally non-fragmented continuous linear habitat |
Moderate
- severe. In some cases fragmented by catchwater channel or existing road |
Ecological
linkage |
Functionally
linked to surrounding terrestrial habitat(s) |
Functionally
linked to surrounding terrestrial habitat(s) |
Potential
value |
High
as a result of the pristine condition and generally low level of disturbance |
Moderate
as a result of low/seasonal base flow and/or catchwater interception |
Nursery/
breeding ground |
Significant breeding grounds of numerous species of conservation interest, including Beijiang Thick-lipped Barb, Romer’s Tree Frog, Short-legged Toad, Hong Kong Newt, several odonates |
No
significant breeding ground or nursery detected |
Age |
Ancient
geomorphological drainage features |
Ancient
geomorphological drainage features |
Abundance/
Richness of wildlife |
Very
high, 119 species of non-avian fauna recorded in these habitats as a whole,
21 species of conservation interest (although 5 species non-aquatic) |
Moderate, 1 species conservation interest (although non-aquatic) |
Ecological value |
Very
high |
Moderate-low,
given the value of the surrounding habitat (secondary woodland, plantation
woodland or tall shrubland) |
8.5.7.1 Grassland
within the Study Area is species poor and hence considered to have low
ecological value (Table
8.21).
Table 8.21 Ecological Evaluation of Grassland Within the Study Area
Criteria |
Grassland |
Naturalness |
Natural
habitat but maintained as a fire plagioclimax |
Size |
Relatively
large as a whole for the Study Area |
Diversity |
Low |
Rarity |
None of the species recorded are rare
in Hong Kong |
Re-creatability |
Readily re-creatable |
Fragmentation |
Minimal |
Ecological
linkage |
Not
functionally linked to any highly valued habitat in close proximity |
Potential
value |
Limited
because of the topographic position of the habitat unless succession is
permitted to occur |
Nursery/
breeding ground |
No
significant nursery or breeding ground recorded |
Age |
Young
in terms of the succession pathway |
Abundance/ Richness of wildlife |
Low, only 16 species of fauna present; no species of
conservation interest |
Ecological value |
Low |
8.5.8 Freshwater Marsh
(Fong Yuen Marsh)
8.5.8.1 A patch of
freshwater marsh is located at Fong Yuen at the northern part of the Study Area
near Lung Tseng Tau. Given that this habitat type is limited within the Study
Area and relatively rare in Hong Kong as a whole (e.g., Dudgeon and Corlett,
1994) and supports an important fish fauna, its ecological value is considered
high (Table 8.22).
Table
8.22 Ecological Evaluation of Fong Yuen
Freshwater Marsh within the Study Area
Criteria |
Fong Yuen
Freshwater Marsh |
Naturalness |
Semi-natural
as the habitat is established on abandoned agricultural fields |
Size |
Relatively
small in size |
Diversity |
Moderate
floral diversity for wetland habitat |
Rarity |
None of the floral species recorded are rare in Hong Kong. Two rare species of fauna are present, including one species of moderate conservation interest and one of very high conservation interest |
Re-creatability |
Readily re-creatable provided that adequate resources are available (man-power, land, finance, re-planting material) and in the absence of disturbance |
Fragmentation |
Not
fragmented |
Ecological
linkage |
Functionally
linked to streams passing through this habitat |
Potential
value |
Moderate
potential value with respect to the planned land-use in surrounding area |
Nursery/
breeding ground |
The
marsh supports a highly significant nursery for the globally endangered and
highly restricted Ricefish (Oryzias
curvinotus), a species of very high conservation interest |
Age |
Establishment
of the marsh presumably does not pre-date establishment of wet agriculture at
the site |
Abundance/
Richness of wildlife |
Moderate,
59 species of fauna recorded at the marsh; 2 species of conservation interest |
Ecological value |
High
due to presence of Ricefish |
8.5.9.1 Wasteland is
found scattered around the northern and southern ends of the Study Area and
covered mainly by weedy plants with low ecological value (see Table 8.23).
Table 8.23 Ecological Evaluation of Wasteland within the Study Area
Criteria |
Wasteland |
Naturalness |
Semi-natural as the habitat is established on heavily disturbed land and inhabited by weedy species |
Size |
Relatively
small in size |
Diversity |
Botanically
poor |
Rarity |
None of the species recorded are rare in Hong Kong |
Re-creatability |
Readily
re-creatable |
Fragmentation |
Moderate |
Ecological
linkage |
Not
functionally linked to any high value habitat |
Potential
value |
Low
potential value with respect to the planned land-use |
Nursery/
breeding ground |
No
significant nursery or breeding ground recorded |
Age |
Young
in terms of the succession pathway |
Abundance/
Richness of wildlife |
Very
low, ten species of fauna present. |
Ecological value |
Low |
8.5.10.1 Agricultural
lands within the Study Area are small in size and intensively modified and
managed by human activities. The ecological value is hence considered low
(Table 8.24).
Table 8.24 Ecological Evaluation of Agricultural Land within the Study Area
Criteria |
Agricultural
Land |
Naturalness |
Man-made
habitat |
Size |
Small
in size |
Diversity |
Poor in botanical diversity |
Rarity |
None
of the species recorded are rare |
Re-creatability |
Readily creatable with adequate resources, i.e. land |
Fragmentation |
Relatively
fragmented given the size of the patches |
Ecological
linkage |
Not
functionally linked to any highly valued habitat in close proximity |
Potential
value |
Potentially
high depending on the agricultural management practices |
Nursery/
breeding ground |
No significant nursery or breeding ground recorded |
Age |
No
information |
Abundance/
Richness of wildlife |
Low,
30 species of fauna recorded; no species of conservation interest |
Ecological value |
Low |
8.5.11.1 Rural area
usually has intensive human activities with limited ecological resources, and
hence has limited ecological value, as shown below in Table 8.25.
Table 8.25 Ecological Evaluation of Village Area Within
the Study Area
Criteria |
Rural Area |
Naturalness |
Man-made habitat with intensive human activities |
Size |
Relatively small in size |
Diversity |
Botanically
poor |
Rarity |
None
of the species recorded are rare in Hong Kong |
Re-creatability |
Readily
re-creatable |
Fragmentation |
Moderate |
Ecological
linkage |
Not
functionally linked to any highly valued habitat in close proximity |
Potential
value |
Low
potential value with respect to the planned land-use |
Nursery/
breeding ground |
No
significant nursery or breeding ground recorded |
Age |
No
information |
Abundance/
Richness of wildlife |
Low,
only 17 species of fauna recorded; no species of conservation interest |
Ecological value |
Low |
8.5.12.1 The
ecological importance of the species identified within the Study Area is
evaluated in accordance with the suggested criteria as stated in Annex 8 of the
EIAO TM, namely protection status, distribution and rarity.
8.5.12.2 Accordingly,
four plant species of ecological interest were recorded and they were all found
in the plantation woodland or secondary woodland around Pak Kung Au, including
the orchids Acampe rigida and Liparis viridiflora, the shrub Pavetta hongkongensis and the tree Artocarpus hypargyraea.
8.5.12.3 Although the
orchids Acampe rigida and Liparis viridiflora, and the shrub Pavetta hongkongensis are considered
common in lowland forest or shrubland habitat in Hong Kong (Siu, 2000; Xing et. al., 2000), they are listed under
the Forestry Regulations (Ch. 96, Section 3). Artocarpus hypargyreus is a common tree species in lowland forest
but is a Category III nationally protected species in China and listed as
vulnerable in the China Plant Red Data Book.
8.5.12.4 Some of these
plants are located on the development footprint of the proposed road. These
include single individuals of Liparis
viridiflora, Acampe rigida, Pavetta hongkongensis and Artocarpus hypargyreus (Figures
8.19a-b).
8.5.13.1 The
ecological importance of the predominantly boulder-shore intertidal habitat at
Pui O Wan was evaluated in accordance with the suggested criteria stated in
Annex 8 of the EIAO TM. The habitat present is composed of a natural boulder
shore line with intermittent sand deposits and such natural habitats are
generally rated higher in the TM. It should, however, be noted that similar
habitat is reasonably common and present in similar locations elsewhere in Hong
Kong. The drainage channel will also lead to an insignificant loss of shoreline
(the drainage channel will incur the loss of less than 5 m of foreshore, including for the stepped channel
itself and a maintenance stairway). The faunal diversity was also low and only
twelve common species were recorded along the whole coastline surveyed and
eleven faunal species were present in the area directly adjacent to the channel
(Appendix H). There was a low abundance of species on the shore although the
molluscs were the most abundant group recorded. All species present, apart from
the clam Donax sp. are found on hard
substrates (often including artificial substrates such as seawalls) throughout
Hong Kong. The surf clam (Donax sp.)
that was recorded in sands deposited between the boulders is also a common
species in Hong Kong although it is distributed in coarse sand rather than hard
substrates. The boulder-shore is not fragmented and functionally linked to the
adjacent marine habitat (particularly the lower shore). The boulder-shore is
not, however, anticipated to represent a significant nursery or breeding
ground. Based on the aforementioned, the overall ecological value of the
shoreline is therefore considered to be low to moderate. As the intertidal
habitat is of low to moderate ecological importance, the area lost to
construction of the channel is insignificant, only the potential impacts due to
discharges (both construction and operational phases are considered further)
and these are discussed below in Section 8.7.7.26 that describes the Southern
Section drainage.
8.5.14.1 Habitats
within the Study Area may be ranked according to their ecological value as
indicated in Table 8.26 below, detailed in ascending order. The stream and
riparian habitats with high base flow were the most ecologically valuable
habitats present, whereas grassland, rural areas, agricultural land and
wasteland were of lowest ecological value.
Table 8.26 Summary of the Ecological Value of Habitats within the Study Area (ascending order of importance)
Habitat |
Ecological Value |
Stream
and Riparian (A) |
Very
High |
Secondary
woodland |
High |
Freshwater
Marsh |
High |
Plantation
(A) |
Moderate
– High |
Tall
Shrub |
Moderate
– High |
Plantation
(B) |
Moderate
– High |
Plantation
(C) |
Moderate |
Shrubland/Grassland
Mosaic |
Moderate |
Stream
and Riparian (B) |
Low-Moderate |
Intertidal Shore (Pui O Wan)
|
Low-Moderate |
Grassland |
Low |
Village
Area |
Low |
Agricultural
Land |
Low |
Wasteland |
Low |
Note: (A), (B), (C) refers to group as
defined in previous tables
8.6 Ecological Impact Assessment Methodology
8.6.1 The objective of the ecological assessment is to predict the direct, indirect, primary and secondary, on‑site and off‑site impacts of the Improvement to Tung Chung Road between Lung Tseng Tau and Cheung Sha. The significance of ecological impacts have been evaluated based on the criteria specified in Table 1, Annex 8 of the TMEIA (TM), as follows:
¨ habitat quality;
¨ species affected;
¨ size/ abundance of habitats affected;
¨ duration of impacts;
¨ reversibility of impacts; and
¨ magnitude of environmental changes.
8.6.2 Impacts are ranked as “minor”, “moderate” or “severe”, although in a few cases, “insignificant” (less than “minor”) or “extremely severe” may also be given. The ranking of a given impact will vary based on the criteria listed above. For example, an impact might be ranked as “minor” if it affected only common species and habitats, or if it affected only small numbers of individuals or small areas, whereas it might be ranked as “severe” if it affected rare species or habitats, large numbers of individuals or large areas. The major factors giving rise to a ranking of “moderate” or “severe” are spelled out in the text as far as possible. As noted in Annex 16 of the TM, a degree of professional judgement is involved in the evaluation of impacts.
8.6.3 Impacts to species or groups assessed as ‘minor’ are predicted to cause a slight, and/or short term reduction in the local population numbers or geographic distribution of a species or group, but the species or groups are predicted to recover from the perturbation with no long-term adverse impacts. Habitat impacts are considered ‘minor’ when no species of conservation or regulatory concern are found, and when the habitat in question was widely distributed locally.
8.6.4 Impacts to species or groups assessed as ‘moderate’ are predicted to cause local reduction of species or group population numbers. The reductions would be long-term, and probably not recoverable, but the species or groups in question are considered widely distributed or common, and abundant on a local, regional, or global scale. Habitat impacts are judged ‘moderate’ when the habitat in question was of limited local or regional distribution or declining in extent, and when the potential for the habitat to support fauna and flora was considered of conservation or regulatory importance.
8.6.5 Impacts to species or groups are assessed as ‘severe’ when they are judged to adversely affect species or groups which are of conservation or regulatory concern locally, regionally, or globally due to scarcity or declining population or distribution trends. Impacts to habitats are considered ‘severe’ when the habitats are found to be limited or declining in geographic distribution, contain plant species of regulatory or conservation concern, or are generally considered by the scientific community to be of local, regional or global importance to the support of wild fauna.
8.6.6 If ecological impacts are found to be significant (i.e., minor to severe) mitigation needs to be carried out in accordance with the TM. Mitigation measures are not required for insignificant impacts. The policy for mitigating significant impacts on habitats and wildlife is to seek to achieve impact avoidance, impact minimisation and impact compensation in that order of priority. Impact avoidance typically consists of modifications to the project design, but may in extreme cases require abandonment of the project (the “no-go” alternative). Impact minimisation includes any means of reducing the scope or severity of a given impact, e.g. through timing of construction works, modification in design, or ecological restoration of disturbed areas following the completion of works. Impact compensation assumes that an irreversible impact will occur upon a given habitat or species and attempts to compensate for it elsewhere, for example, by enhancement or creation of suitable habitat. Compensation may take place on-site or off-site.
8.6.7 Construction of the alignment will result in permanent loss of habitat. There will be an additional temporary loss resulting from the construction of haulage roads, works areas and temporary work sites. The temporary areas will not be permanently occupied and may, therefore, be left to re-establish naturally or be re-instated once the construction works have been completed.
8.6.8 In calculating the permanent and temporary areas of habitat lost, all areas under the permanent alignment, including all slopes and embankments have been regarded as permanent loss. All areas within the site boundary but not forming a permanent part of the road, namely off-line sections of the haul road and the works areas have been assumed to be temporarily lost.
8.7 Construction Phase Ecological Impact Assessment
8.7.1
General
8.7.1.1 Construction phase impacts have been assessed and evaluated against the major impacts typically associated with road projects, namely habitat loss, habitat fragmentation, and disturbance (English Nature, 1994; Reijnen et al., 1995; Treweek, 1999). Construction phase impacts to fauna are related to direct habitat loss and fragmentation of habitat, the latter applicable to off-line alignment options only as the existing Tung Chung Road can be considered as an in-situ permeable barrier to most fauna). Secondary impacts are related to the effect of habitat loss and subsequent reduction of food resources and breeding sites. The proximity of the project to sensitive habitats renders it imperative that proper control is exerted on handling and disposal of any excavated material.
Table 8.27 Habitat Loss Arising from the Project (ha)
Habitat |
Study Area
(permanent loss) |
Study Area
(temporary loss) |
Existing Slope
Remediation* |
Secondary Woodland |
2.14 |
- |
0.11 |
Plantation Woodland |
3.98 |
1.01 |
0.04 |
Tall shrub |
6.24 |
0.2 |
0.08 |
Shrubland – Grassland Mosaic |
0.62 |
0.05 |
0.04 |
Grassland |
0 |
- |
0 |
Freshwater Marsh at Fong Yuen |
0 |
- |
0 |
Agricultural Field |
0 |
- |
0 |
Rural Development (Village Area) |
0 |
- |
0 |
Wasteland |
0.23 |
- |
0.01 |
Stream Course |
0.01 |
- |
0 |
*Obsolete sections of existing
Tung Chung Road
Habitat loss
8.7.2.1 Secondary
woodland, when covering an area greater than one hectare, is classed as
important in Annex 8 of the TM EIAO. Secondary woodland present in the Study
Area was also rated highly in habitat evaluations made for the current project
(Table 8.15). Although patchily distributed, a total of 193.6 ha of this
habitat is present within the Study Area, of which 2.14 ha will be permanently
lost as a consequence of road construction, including the cycle track between
Shek Mun Kap Road and Lung Tseng Tau,
with a further 0.11 ha loss as a result of slope remediation works on the
obsolete sections of the existing Tung Chung Road.
8.7.2.2 Loss of secondary
woodland on the on-line section (chainage 1.000 to 3.200, Figures 2.2 to 2.5)
will be small, amounting to 0.08 ha, including the area lost to the cycle
track. The northern off-line section (chainage 3.200 to 4.500, Figures 2.5 to
2.7) will result in minor loss of 0.28 ha of this habitat, while the southern
off-line section (chainage 4.500 to end, Figures 2.7 to 2.11) will incur a
further moderate loss of 0.81 ha. The bus bay facilities proposed at San Shek
Wan in the extreme south-east of the Study Area will engender a further
moderate loss of secondary woodland.
Note that no rare or protected flora were recorded in this habitat.
Also, although four locally rare species of butterfly were recorded in this
habitat as presented in Figures 8.18a-f (Gaudy Baron, Pale Cerulean, Common
Rose and Large Branded Swift), none of the known foodplants of these species
(e.g., Macrosolon cochinchinensis, Scurrula parasitica, Pongamia pinnata, Derris trifoliata, Aristolochia
tagala, A. fordiana) were recorded either in this habitat or anywhere else in
the Study Area. Habitat loss is, therefore, not anticipated to have impacts on
floral species important for these butterfly species. Loss of habitat will
inevitably result in a reduction in available nectar sources for adult
butterflies. However, this impact is expected to be insignificant as adult
butterflies have moderate to high mobility and should be able to utilise other
nectar sources in the vicinity, particularly the large area of secondary
woodland remaining. Also, no food plants of butterfly species of conservation
interest were recorded.
8.7.2.3 A drainage
pipeline for use during both the construction and operational phases will be
constructed through secondary woodland to discharge at Pui O Wan (Section
6.3.3.25; Figure 6.2j). The pipeline will be 180m long, and will result in a
loss of 0.09ha of woodland. No species of conservation importance were recorded
in this area of woodland.
8.7.2.4 Habitat loss
could affect the endemic Romer’s Tree Frog inhabiting the secondary woodland
patch at Lung Tseng Tau (chainage 1.100 to 1.200, Figure 2.1). During the surveys, the Romer’s Tree Frog
was not noted in the secondary woodland area to the west of the road affected
by the proposed cycle track. However,
the species was noted on the edge of the marsh and so it is very possible that
it uses this stretch of woodland.
However, loss of woodland in these two areas is limited to small fringe
sections close the Tung Chung Road and is anticipated to be insignificant in
terms of the secondary woodland area as a whole. Notwithstanding, given the
conservation importance of the Romer’s Tree Frog, habitat loss is considered to
have a minor impact on the endemic Romer’s Tree Frog.
8.7.2.5 Habitat loss is a
threat to birds as it may be linked to direct mortality, species displacement,
and is most severe in species that have an inability to translocate to suitable
habitat elsewhere (Treweek, 1999). Although species-area relationships have
been extensively studied, it is difficult to estimate the minimum area of
habitat required for most animals and this is more difficult with highly mobile
species such as birds. It has been estimated that the minimum woodland habitat
required to support temperate bird species in The Netherlands must be larger
than 2 or 3 ha otherwise the characteristic typical ‘core’ woodland species are
not supported (Treweek, 1999). A
minimum of 50 ha area of woodland has been reported to be required to support
viable populations of core (characteristic) woodland species. As the areas of
secondary woodland in the Study Area are relatively small they are unlikely to
provide habitat that is of high enough quality to sustain large numbers of bird
species and this was reflected in the low numbers of species present throughout
the Study Area. Although there is
potential for some loss of higher quality woodland habitat that is utilised by
birds, the overall impact of losing the woodlands present in the Study Area on
bird populations is insignificant. Only 16
species of birds, none of conservation interest, were recorded in this habitat.
Fragmentation
8.7.2.6 Fragmentation
impacts are generally likely to be insignificant, since this habitat is quite
patchily distributed within the Study Area, and the road alignment generally
appears to impact only the edges of these patches. However, at chainages 3.200
to 3.400 (Tai Tung Shan) and 6.500 to 6.600 (Figures 2.5 to 2.10), as well as
at the site of the proposed bus bay facilities, fragmentation impacts may be
moderate due to the road alignment bisecting patches of secondary woodland. The
endemic Romer’s Tree Frog, which is a species of very high conservation
interest, with low to moderate mobility, was not recorded at these specific
locations but was present in other patches of secondary woodland within the
Study Area. Several bird species were recorded from this habitat, but these
animals are highly mobile and unlikely to be significantly impacted, since the development
footprint is narrow and easily negotiable for flying animals.
Disturbance
8.7.2.7 Disturbance
impacts are temporary and will be more severe for species with lower avoidance
ability. Four butterflies of moderate conservation interest (Gaudy Baron, Pale
Cerulean, Common Rose and Large Branded Swift) were recorded in secondary
woodland that are moderately to highly mobile as adults. However, no evidence
of the relatively sessile larvae was noted, and known larval foodplants were
not recorded in this habitat. Since there is no evidence of breeding,
disturbance impacts on these species are considered to be insignificant.
8.7.2.8 Disturbance to
larger mammals and birds during the construction phase is likely to be
associated with noise, construction traffic and the greater presence of human
activities on-site. Most larger mammals are nocturnal and will suffer only
minor impacts, provided that construction activity ceases during the night.
Short-term disturbance to birds can affect the time they have available for feeding,
whilst longer term effects can cause a reduction in use of a particular area
for feeding and/ or breeding (Hill et al.,
1997; Treweek, 1999). Although the effects of disturbance on birds are
difficult to quantify, many bird species in Hong Kong (and elsewhere) are known
to habituate to disturbance and noise (Melville, 2000; quoted in South China
Morning Post Wednesday 9 May 2000). It is, therefore, unlikely that bird
species present in the Study Area will suffer significant disturbance effects
attributable to the road project and, as such, these construction phase
disturbance impacts are considered to be insignificant.
8.7.2.9 The endemic
Romer’s Tree Frog, a species of very high conservation interest, was recorded
from various secondary woodland locations within the Study Area, some of which
(e.g., Lung Tseng Tau, chainage 1.100 to 1.200; Shek Mun Kap, near chainage
1.700 to 1.800, see Figure 2.2) will be potentially disturbed by construction
activities such as earth-moving works associated with the project. Locations
were the Romer’s Tree Frog was recorded during the surveys is summarised in
Figures 8.16a-g. Tadpoles of this
species are relatively sessile, while adults are small, have a fairly narrow
habitat tolerance and limited dispersal ability. Disturbance impacts to this
species are considered moderate.
Habitat loss
8.7.3.1 Plantation
woodland occurs primarily in two large areas within the Study Area. One such
area at Pak Kung Au (chainage 3.700 to 5.200) has been evaluated as of moderate
to high value; while the plantation woodland at the Cheung Sha catchwater
(chainage 5.500 to 6.500) has been rated moderate to high in value on the basis
of the understorey structure and composition. The plantation woodland on the
hillslope to the east of the Tung Chung Road is of moderate value. Overall, the
Study Area contains 81.4 ha of this habitat, of which 3.98 ha will be
permanently lost as a consequence of road construction, with an additional
temporary loss of 1.01 ha for haulage roads. However, this is a re-creatable
man-made habitat, containing several naturalised exotics, and impacts from
habitat loss are considered insignificant.
8.7.3.2 Note that
individuals of four floral species of moderate conservation interest (the tree Artocarpus hypargyreus, the shrub Pavetta hongkongensis and the orchids Acampe rigida and Liparis viridiflora) were
recorded in this habitat. An individual of Artocarpus
hypargyreus was located in very close proximity to the proposed road (at
chainage 5.080, Figure 2.7, near Stream 26), while single individuals of Pavetta hongkongensis and Liparis viridiflora were located close
together on the development footprint (chainage 4.380, Figure 2.6, near Stream
22). Loss of these individual specimens is considered a minor impact. All of these
species are, however, common in Hong Kong. Also, four locally rare species of
butterfly were recorded in this habitat (Black-veined Sergeant, Commander, Pale
Cerulean, and Small Grass Yellow), although none of the known foodplants of
these species (e.g., Fraxinus retusa,
Osmanthus fragrans, Uncaria hirsute, Wendlandia sp., Pongamia
pinnata, Derris trifoliata, Chamaecrista mimosoides) were recorded
either in this habitat or anywhere else in the Study Area. Therefore, loss of
plantation woodland is anticipated to have insignificant impact on floral
species important for butterflies of conservation interest.
Fragmentation
8.7.3.3 Fragmentation
impacts are generally evaluated as being insignificant, although the proposed
road bisects two large areas of plantation woodland. One individual of Romer’s
Tree Frog was encountered in plantation woodland adjacent to the existing Tung
Chung Road at 190m, close to the intersection with stream No. 27. This species
has low to moderate mobility and is of very high conservation interest, but was
rarer in this habitat than in secondary woodland, shrubland or riparian
habitats within the Study Area.
8.7.3.4 The Mock Viper,
which is of moderate conservation interest, was also recorded in plantation
woodland (one individual within the patch between chainage 5.500 and 6.500,
Figures 2.9 and 2.10). This species has only moderate mobility and habitat
fragmentation may impact adversely on availability of suitable foraging areas.
8.7.3.5 Several bird
species were recorded from this habitat (various locations throughout the study
area) including Greater and Lesser Coucal’s (moderate conservation interest),
but these species are highly mobile and unlikely to be adversely impacted,
since the development footprint is narrow and easily negotiable for flying
animals.
Disturbance
8.7.3.6 Disturbance
impacts are temporary and will be more severe for species with lower avoidance
ability. Four butterflies of moderate conservation interest (Black-veined
Sergeant, Commander, Pale Cerulean, and Small Grass Yellow) were recorded in
plantation woodland as moderately to highly mobile adults (Figure 8.18a-f).
However, no evidence of the relatively sessile larvae was noted, and known
larval foodplants were not recorded in this habitat. Since there is no evidence
of breeding, disturbance impacts on these species are considered to be
insignificant.
Habitat loss
8.7.4.1 Tall shrubland
occurs extensively throughout the Study Area, occupying a total area of 131.7
ha, of which 6.2 ha will be permanently lost due to road construction, with
temporary loss of 0.2 ha arising from construction of haulage roads. This
habitat was rated as having moderate to high ecological value in the Study
Area. Some 3.07 ha of this habitat will be lost along the online section
(chainage 1.000 to 3.200, Figures 2.2 to 2.5), 1.52 ha in the northern off-line
section (chainage 3.200 to 4.500, Figures 2.5 to 2.7) and a further 1.84 ha in
the southern offline section (chainage 4.500 to end, Figures 2.7 to 2.11). In
addition, a small area of this habitat (0.007 ha) will be lost at the bus bay
facilities at San Shek Wan and 0.08ha to the slope remediation works. Due to
the extensiveness of this habitat within the Study Area, however, loss of 6.52
ha is considered as being a minor to moderate impact.
8.7.4.2 No rare or
protected flora were recorded along the development footprint. Three locally
rare butterfly species of moderate conservation interest (Common Rose, Pale
Cerulean, Small Grass Yellow) were recorded in this habitat (Table 8.14;
Figures 8.18a-f). However, larval foodplants of these species (Aristolochia tagala, A.
fordiana, Pongamia pinnata, Derris trifoliata, Chamaecrista mimosoides) were absent. Therefore, habitat loss is
not expected to impact on floral species of conservation significance to butterflies.
8.7.4.3 Three bird
species of moderate (Greater and Lesser Coucals) and high (Grey Nightjar)
conservation interest were recorded within this habitat. All of these species
are highly mobile and impacts are considered insignificant.
8.7.4.4 Romer’s Tree Frog
was recorded breeding at several locations in this habitat, particularly on the
northern side of the Study Area at Lung Tseng Tau to Pak Kung Au (chainage
1.000 to 4.500) (Table 8.14; Figures 8.16a-g). This species has low mobility
and impact of habitat loss is considered as minor to moderate, depending upon
whether breeding sites (small seepages) are destroyed. Three dragonfly species
of conservation interest, the endemic Melligomphus
moluami, the endemic subspecies Leptogomphus
elegans hongkongensis and Zygonyx
iris insignis were recorded foraging in this habitat (Table 8.14; Figures
8.18a-f). These species are more associated with riparian habitat and loss of
tall shrubland habitat at the scale engendered by the proposed road development
is considered an insignificant impact.
Fragmentation
8.7.4.5 Tall shrubland
habitat is already highly fragmented in the Study Area. In the northern section
where losses will be greatest the habitat is fragmented by the existing Tung
Chung Road and further fragmentation arising from the proposed road development
is considered to be insignificant.
Disturbance
8.7.4.6 Three butterflies
of moderate conservation interest (Pale Cerulean, Common Rose and Small Grass
Yellow) were recorded in tall shrubland (Table 8.14; Figures 8.18a-f). However,
no evidence of the relatively sessile larvae was noted, and known larval
foodplants were not recorded in this habitat. Since there is no evidence of
breeding, disturbance impacts on these species are considered to be
insignificant. Such impacts are also considered to be insignificant for the
three dragonfly species of conservation interest (Melligomphus moluami, Leptogomphus
elegans hongkongensis and Zygonyx
iris insignis) all of which are moderately or highly mobile as adults and
do not breed in tall shrubland.
8.7.4.7 Ferret
Badger and Chinese Cobra, both recorded from tall shrubland within the Study
Area (Table
8.14; Figures 8.17a-b and 8.16a-g respectively), will
potentially be impacted by disturbance, since construction works will be
continuous along a long front. Although these relatively mobile species will be
able to avoid areas of high disturbance, the nature of the development will
present a barrier to movement for these species during times of construction
activity, effectively reducing available foraging areas. However, the Ferret
Badger is nocturnal, and will not be active during times of construction
activity and in addition, much undisturbed habitat will be present, even during
times of construction activity. It is therefore anticipated that disturbance
impacts on these two species of conservation interest will be insignificant.
8.7.5
Shrubland-grassland mosaic
Habitat loss
8.7.5.1 This habitat
accounts for a total area of 115.3 ha within the Study Area. An area of 0.62 ha
of this habitat, rated as of moderate ecological value, will be permanently
lost as a consequence of the new road development. Temporary habitat loss
arising from construction of haulage roads will amount to 0.05 ha with a
further 0.39ha as a result of the slope remediation works. It should be noted
that the moderate ecological value rating is made to some extent on the basis
of the combined faunal assessment with the tall shrubland habitat (for reasons
explained in Section 8.4 above). The Romer’s Tree Frog was not, however,
recorded in shrubland-grassland mosaic.
8.7.5.2 No rare or
protected flora were recorded in this habitat along the development footprint.
Therefore, habitat loss is not expected to impact on floral species of
conservation significance.
8.7.5.3 Three bird
species of moderate (Greater and Lesser Coucals) and high (Grey Nightjar)
conservation interest were recorded within this habitat (Table 8.13; Figure
8.15). Although of some conservation interest both of the coucal species are
common and widespread in the territory. All three of these species are highly
mobile and able to disperse into nearby areas of similar habitat. Impacts of
habitat loss are therefore, considered, insignificant.
Fragmentation
8.7.5.4 Shrubland-grassland
mosaic habitat is already fragmented in the Study Area. Given the fact that the
only species of conservation interest recorded in this habitat were birds, with
very high mobility, the further, small-scale fragmentation which will be
engendered by construction of the new road is considered to be insignificant in
terms of impacts on fauna.
Disturbance
8.7.5.5 Three birds of
moderate to high conservation interest (Greater Coucal, Lesser Coucal and Grey
Nightjar) were recorded in shrubland-grassland mosaic. However, since these
species have high dispersal ability and are readily able to avoid disturbed
areas, disturbance impacts of the new road are considered to be insignificant.
It should also be noted that traffic volumes will be low, and that Grey
Nightjar is nocturnal and will therefore be active at times when traffic flow
is lowest.
8.7.6.1 This habitat
accounts for a total area of 43.5 ha within the Study Area. However, the
proposed road development will not encroach on this habitat. In view of this,
and the fact that grassland in the Study Area was rated as being of low
ecological value, any impacts to this habitat, and to the species occupying it,
arising from the project are considered to be insignificant. No species of conservation interest were
recorded in this habitat.
8.7.7
Stream and riparian A
(relatively high base flow): Tung Chung Stream, Cheung Sha Stream, Stream No.’s
15, 18, 19, 21, 23, 24, 25, 26, 27, 32, 35, 40, 41, 42, 43
General
8.7.7.1 Based upon both
wet and dry season field surveys, numerous streams in the Study Area are
apparently seasonal, or of very low
base flow, some influenced by the water gathering grounds and catchwater
system, and the surveys have shown these streams to be of lower ecological
value than the permanent streams with reliable discharge, upon which fully
aquatic fauna are dependent.
8.7.7.2 Based upon the surveys, the streams can be divided
into two broad categories comprising those with generally higher base flow
supporting species of conservation interest, and those with generally lower
base flow not supporting species of conservation interest. A summary of the
quality of the two sets of streams is provided in Table 8.20 and a summary of
the flow details of each stream is provided in Table 8.15.
Habitat loss
8.7.7.3
It has been necessary to provide a balance between the provision of
elevated structures which span the streams and avoid direct impacts and the
visual impacts of these structures.
However, based upon the fact that loss of stream bed in streams of high
ecological value, and its replacement with smooth-walled drainage channels, can
incur loss of refugia, foraging and predator avoidance opportunities for
aquatic fauna such as fish, amphibians (particularly tadpoles) and odonate
larvae, development of the project has sought to avoid impacts on key streams.
Thus, new bridge structures have been proposed for as many of the streams
crossed by the new road as possible, with emphasis on the streams which has
been confirmed by the wet and dry season ecological surveys to be of high
ecological value, as discussed in this section. For all but four of these streams of high ecological value,
namely Streams 15, 18, 19 and 21 (Figure 8.5), stream modifications, and thus
direct impacts and habitat losses, have been avoided, with the new road passing
over the water courses on bridge structures.
Thus bridges will be provided for streams 23, 24, 25, 26, 27, 32, 35, 40
and 43 for ecological reasons as summarised in Table 8.15. Streams 39, 41 and
42 are not crossed by the road and will not therefore be impacted by the
project.
8.7.7.4 The bridge
piers/abutments will be constructed at least 5m away from the streams and
excavation works for the columns will be protected by the drainage works
described in more detail below and in Section 6, in order to protected from any
runoff entering the streams.
8.7.7.5 The haul road
will generally follow the alignment of the new road, but will bypass the
construction site at some stream courses where longer bridges are proposed.
However, in order to avoid affecting these streams, the haulage road will be
designed to pass over the stream courses on temporary steel bridges of at least
twice the width of the stream thus, protecting against direct impacts to the
streams and the riparian vegetation.
8.7.7.6 Tung Chung Stream
and Cheung Sha Stream are not crossed at any point by the proposed road
alignment and thus will not be directly affected by the scheme.
8.7.7.7 Thus, habitat
loss on key streams will be restricted to Streams 15 (extension of existing
bridge resulting in about 6m loss of stream bed), 18 (widening of existing
culvert by 20m), 19 and 21 (30m and 50m culverts, respectively, to be
constructed at road crossing). The culverting works on streams 18, 19 and 21
will lead to a loss of the existing stream bed as the stream is modified in
such a way that the flow is altered and existing streambed will dry out. The modifications
to Streams 15, 18, 19 and 21 cannot be avoided, as discussed in Sections
6.3.4.5 to 6.3.4.9.
8.7.7.8 Impacts may be
incurred in the streams as a result of the destruction of the natural stream
bed, with potential deleterious impacts (crushing, displacement, entrapment) on
sedentary aquatic fauna such as tadpoles of rare amphibian taxa. This may be
compounded by destruction of riparian vegetation with deleterious impact on
rare amphibians (e.g., Romer's Tree Frog, Short-legged Toad, Lesser Spiny Frog)
for which riparian vegetation is a highly important habitat, particularly
during the breeding season, which lasts from March to August but peaks during
April to June.
8.7.7.9 The impact of
habitat loss is minor in stream 15 as even though only about 6m of stream bed
will be lost, which is negligible in relation to the entire stream length, the
Hong Kong Newt is present. Also based upon, the number of aquatic species of
conservation interest present (various amphibians, see Table 8.14) and also the
size of habitat lost (20-50m) for streams 18, 19 and 21, the impacts are
predicted to be also minor.
Fragmentation
8.7.7.10 Fragmentation is
not expected to be an impact for streams over which an elevated structure is
placed (stream No.’s 23, 24, 25, 26, 27, 32, 35, 40, 41, 42, 43). Fragmentation
may, however, be an impact in the newly culverted streams (19 and 21) and
further fragmentation may occur through the extension of the culvert in Stream
18 by 20m in both construction and operational phases if culvert design
restricts the access of aquatic fauna such as fish, tadpoles and odonate
larvae. Stream 18 supports the Lesser Spiny Frog (high conservation interest),
stream 19 supports the Hong Kong Newt (very high conservation interest) and
stream 21 supports both the Lesser Spiny Frog and Romer’s Tree Frog (very high
conservation interest). However, these fauna were recorded at low densities in
these particular streams (see Appendix H) and generally have greater mobility
than fish, with adult stages capable of movement in the terrestrial riparian
zone, and no fish of conservation interest were recorded in streams 18, 19 and
21.
8.7.7.11 At stream 15, a
small population of the very high conservation interest Beijiang Thick-lipped
Barb is isolated between the existing bridge culvert and a sheer natural rock
face immediately upstream. The protected Hong Kong Newt was also present in
Stream 15 although further fragmentation is not considered to be significant
impact to the species as it has higher mobility than the Beijiang Thick-lipped
Barb. The bridge widening works in Stream 15 will
comprise digging a trench for laying of the permanent drainage pipeline and
then constructing a concrete base slab as the foundation for the bridge
extension. The base slab will take up
some 6 metres of streambed. The works
proposed at this stream are unlikely to impact on this small population, which
is already isolated by the existing topography. This additional loss of
streambed is not considered to increase fragmentation of stream 15
significantly. Owing to the conservation status of the Beijiang Thick-lipped
Barb it is, however, recommended that, to enhance the population in the
catchment (the species is also recorded in the larger Tung Chung Stream of
which stream 15 is a tributary) this isolated population be evacuated and
released downstream of the bridge, as detailed in Section 8.9.
8.7.7.12 Stream 18 is
already culverted under the existing Tung Chung Road, however, this culvert
will be lengthened by 20m to accommodate the new road directly adjacent to it.
In light of the presence of species of conservation interest, fragmentation
impacts to stream 18 are, therefore, considered to be minor. The new culverts
to be constructed for Streams 19 (a 30m culvert) and 21 (a 50m culvert) will
also cause fragmentation impacts on aquatic fauna of conservation interest
present that are anticipated to be minor. It is therefore recommended that the
entrance and exits to the culverts are designed in a way so as to not create a
barrier to fish or other aquatic fauna such as tadpoles. It is also proposed that the new culverts
for Streams 19 and 21 be designed in such a away as to create pools along their
length which will aid fish and faunal transfer (see Section 8.9).
Disturbance
Direct Impacts on Streams
8.7.7.13 Unlike the other
streams deemed to be of high ecological value which are crossed on bridge,
Streams 15, 18, 19 and 21 will be subject to works in the streams themselves
and impacts are likely to be linked to some siltation of the water course
during construction. Siltation of the water body can clog the gills of fish,
tadpoles and odonate larvae, causing death by asphyxiation. Finer silt
particles may also clog the feeding apparatus of these organisms, reducing
foraging efficiency. Increased water turbidity arising from siltation also
impedes foraging success, particularly for predaceous taxa (such as odonate
larvae, tadpoles and some fish). These taxa may be further impacted by die-off
of prey items associated with increased siltation. Streams 18, 19 and 21
currently support highly sensitive species of amphibian of high or very high
conservation interest and steam 15 supports the Beijiang thick-lipped Barb and
Hong Kong Newt, also of high conservation interest (Section 8.4).
8.7.7.14 In
respect of streams 18, 19 and 21, it is proposed to construct the culvert
section prior to its connection with the stream, thus avoiding any direct
impacts on the stream course during this time.
Thus, the potential for high suspended solids will be limited to the period
when the culvert is connected up at either end and stream flow is directed
through the culvert. This process will
comprise damming the original path of flow, which is not expected to generate
large amounts of suspended solids. Also
the activity is short term taking a matter of days only. Coarse material will settle out rapidly,
probably within the culvert itself and finer material in the water column will
be progressively more diluted as it flows down stream. It should be noted that
spate (flood) events that commonly occur during the wet season also lead to
high suspended particles in the water column and it is likely that the
organisms present in streams in the study area are adapted to fine silt
particles. The overall ecological impacts associated with disturbance of stream
bed sediments in streams 15, 18, 19 and 21 are, therefore considered to be
insignificant.
8.7.7.15 As noted above,
the bridge widening works in Stream 15 will
comprise digging a trench for laying of the permanent drainage pipeline and
then constructing a concrete base slab as the foundation for the bridge
extension. The base slab will take up
some 6 metres of streambed. However,
prior to these works commencing, whatever flow is in the stream will be ponded
by building a dam across the stream, upstream from the works. A temporary pipeline will then divert the
stream water around the works area into the unaffected downstream area. Once the base slab has been completed, the
dam will be removed and the stream will flow across this to the existing bridge
base slab. The works will be relatively
short term, taking approximately 4 weeks to construct the trench and a similar
time period for the base slab. However,
as all natural stream flow will be diverted, the potential for suspended solids
migrating downstream is minimal. The potential
is further reduced by the works being undertaken in the dry season. It should
be noted that spate (flood) events that commonly occur during the wet season
also lead to high suspended particles in the water column and it is likely that
the organisms present in streams in the study area are adapted to silt
particles. The overall ecological impacts associated with disturbance of stream
bed sediments in streams 15, 18, 19 and 21 are, therefore considered to be
insignificant.
Construction Run-off
8.7.7.16 Unpolluted stream
courses are highly sensitive habitats.
While the majority of the streams are crossed on structure, as noted
above, and only four of the streams of high ecological value will be subject to
works within the stream courses themselves, all the streams are vulnerable to
indirect impacts associated with construction site run-off. Siltation may not only impact the streams
crossed by the road, but also the Tung Chung Stream since these streams are
tributaries of the latter. The Tung Chung Stream is of very high ecological
significance, supporting important fish fauna.
8.7.7.17 However, a
comprehensive drainage system has been proposed for both the northern and
southern sections of the new road. Full
details of the system are provided in Section 6. In both cases the temporary drainage system will be in place
before any major roadworks such that all construction run-off is collected and
treated prior to discharge.
Northern
Section Drainage
8.7.7.18 In the northern
section, part of the permanent drainage system will be built in advance and a
special carrier pipe/drainage channel will collect all run-off from the
northern road section from the crest and transport it to a discharge outfall in
the “Wong Lung Hang Channel” nullah near Ha Ling Pei. In this way, no construction run-off will be discharged into any
streams crossed by the northern section of the alignment and thus impacts on
Tung Chung Stream will also be avoided.
8.7.7.19 Key elements of
the drainage system to improve its effectiveness include:
¨
construction of the off-line section of the road may only
commence when either the pipeline trench or carrier pipe has been put in place
up to Tai Tung Shan Reservoir;
¨
during excavation work for the drainage system itself, each
stretch of dug channel will be concrete lined before the end of each day to
minimised run-off. Control and proper disposal of excavated material in
accordance with the Waste Management Plan shall be undertaken;
¨
all temporary drainage channels shall be lined with concrete
to prevent erosion;
¨
the new bridge piers/abutments will be constructed at least
5m away from the streams and excavation works for the columns will be protected
by the drainage works; and
¨
hinterland drainage shall be collected by the use of
perimeter channels and diverted to the nearest stream course to prevent
external run off from crossing the site in order to prevent it becoming
contaminated and to minimise the amount of polluted runoff to be controlled.
8.7.7.20 Other measures
which are proposed during the construction phase to minimise run-off and the
effects on streams include:
¨
temporary cut slopes shall be covered with tarpaulin during
rainfall when not being worked to prevent erosion;
¨
major stockpiles shall be sited outside the Country Park and
away from stream courses;
¨
spoil heaps shall be covered at all times to minimise losses
in the wet season and reduce the dust emissions during the dry season to
minimise impacts on air quality;
¨
stock piled materials shall be contained in a designated
area down gradient from any stream or up gradient with a suitably constructed
barrier to reduce loss of materials to the stream; and
¨
no oil or fuel shall be stored within the Country Park or
the water gathering grounds.
8.7.7.21 The construction
of the haul road will also involve some earthworks and in order to reduce the
areas of exposed earthworks during this phase, the contractor will be required
to pave the off-line section of haul road and associated slopes within 3 days
of the completion of individual sections of the off-line haul road. The temporary drainage system would be
constructed concurrently to the formation of the haul road but the contractor
would be required to progress the drainage system in advance of the haul road
formation to ensure proper runoff control before the road is paved.
8.7.7.22 Based upon the
incorporation of the measures outlined above, impacts on the northern streams
(including the ecologically rich Tung Chung Stream) due to sediment run-off are
considered to be insignificant.
8.7.7.23 High suspended
solid loads draining into the Tung Chung Stream would be discharged into the
Tung Chung Bay where the San Tau SSSI is located. This protected location
contains seagrass beds (Halophila ovata and
Zostera japonica) which could
potentially be impacted (reduced photosynthesis) by high suspended solids in
the water column. A sedimentation tank is, however, also proposed during the
construction phase for the treatment of all discharge into the nullah in order
to protect the Tung Chung Bay from elevated suspended solids. Based upon the
calculation in Section 6.3.3.15, any construction run-off into Tung Chung Bay
could be diluted up to 40 times, even without the further dilution effects of
the marine water and other catchments on the west valley. It should be noted that the seagrass bed at
San Tau SSSI has been subject to impacts associated with the reclamation works
for the new airport at Chek Lap Kok and the North Lantau Highway. The seagrass successfully recovered from
this disturbance once the works were completed. In addition, in view of the on-going and planned reclamation
works in northern Tung Chung, the additional impact of any sedimentation
arising from the current project should be limited.
8.7.7.24 Based upon this
and the fact that the run-off will be treated before discharge, ecological
impacts on Tung Chung Bay and ecological communities present including seagrass
beds are predicted to be insignificant.
Southern
Section Drainage
8.7.7.25 In the southern
section, since any drainage system will need to be carried across the new
elevated structures along this section of the route, it will generally not be
possible to construct the system ahead of the main roadworks as is proposed in
the northern section of the alignment.
Thus, the southern alignment is divided into small catchments in order
to enhance the control of run-off and a temporary drainage system provided
whereby the hinterland drainage is collected separately, as for the northern
section, and the run-off is treated via a sedimentation tank prior to discharge
into the adjacent streams. Discharge
into the streams which ultimately run into the catchwater are also treated via
an oil interceptor.
8.7.7.26 Run-off from the
works site at the new junction with South Lantau Road will also be treated via
a temporary sedimentation tank prior to discharge into the proposed carrier
pipe discharging on the foreshore of Pui O Wan (Figure 6.2j). This part of the permanent drainage system
will be constructed in advance in order for it to be used during the
construction phase. As discussed in Section 8.4.11, there are no species
present on the shore at Pui O Wan that are of conservation interest and the
boulder shoreline has an overall low to moderate ecological value. The drainage
channel will lead to an insignificant loss of some predominantly hard-substrate
(mostly boulder) shoreline as the drainage channel will incur the loss of less than 5 m of foreshore, including
for the stepped channel itself and a maintenance stairway.
Construction-phase impacts including runoff is, therefore considered to
represent an insignificant ecological impact to the intertidal species present
in Pui O Wan as run-off will be treated via a sedimentation tank. Significant
concentrations of contaminants from road runoff are not predicted during the
operational-phase (Section 6.4.1). As discussed above for the construction
phase, the operational-phase impacts to
intertidal organisms attributable to discharges of road runoff are also
considered to be insignificant.
8.7.7.27 While discharge
into the local streams, catchwater and sea at Pui O Wan cannot be avoided, the
proposed construction drainage system minimises impacts by dividing the areas
of discharge into small units, thereby reducing the amount of discharge into
any one stream and also by treating the run-off prior to discharge. The control
measures highlighted above in Section 8.7.7.19 and 8.7.7.20 are also applicable
to the southern section.
8.7.7.28 Based on the
measures outlined above, impacts on the streams in the southern study area
including the Cheung Sha Stream due to run-off and sedimentation are considered
to be insignificant.
8.7.7.29 In view of the
foregoing, disturbance impacts are rated as minor for streams 19 and 21 and
insignificant for streams 15 and 18. Stream No.’s 23, 24, 25, 26, 27, 32, 35,
40 (Cheung Sha Sheung Tsuen Stream) and 43 will be crossed by elevated
structures, with bridge supports at least 5m away from the stream bed.
Disturbance impacts on these streams will be insignificant. Stream No.’s 39 and
41 and 42 are not crossed by the road alignment. All streams will be protected
by the proposed drainage system and impacts are predicted to be
insignificant.
8.7.7.30 Based upon the
importance of the Tung Chung Stream, Cheung Sha Stream and Cheung Sha Sheung Tsuen stream which have
been shown to contain fish species of conservation importance, a summary of the
potential impacts is provided in Section 8.7.8 to 8.7.10 below.
8.7.8.1 A drainage system
will be constructed that will lead to no discharges into the Tung Chung Stream
thereby protecting the valuable fauna present. The existing road widening will
also be to the east of the stream thereby allowing the existing road to act as
a buffer between construction works and the watercourse. No ecological impacts
are therefore predicted for the Tung Chung Stream.
8.7.9.1 The selected
alignment was chosen in some respects due to the distance away from the
ecologically important Cheung Sha Stream thereby minimising the potential for
impacts (only two small tributaries Stream No.’s 25 and 26 are crossed by the
road). The drainage system for construction phase activity will treat run-off
(sedimentation tank) prior to discharge into streams and no ecological impacts
are thereby anticipated. No ecological impacts are therefore predicted for the
Cheung Sha Stream.
8.7.10
Cheung Sha Sheung Tsuen
Stream (Stream 40)
8.7.10.1 This ecologically
important stream (contains species of conservation interest including
Philippine Neon Goby and Black-headed Thick-lipped Goby) will be avoided as it
is crossed by a bridge. The drainage system for construction phase activity
will as for other southern area streams treat run-off (sedimentation tank)
prior to discharge and no ecological impacts are thereby anticipated. No
ecological impacts are therefore predicted for the Cheung Sha Sheung Tsuen Stream.
8.7.11
Stream and riparian B
(relatively low base flow): stream No.’s 1-14, 16, 17, 20, 22, 28-31, 33, 34,
36-39, 44
Habitat loss
8.7.11.1 In order to
provide new bridges as far as possible, in addition to the bridges provided for
the streams of high ecological importance detailed above, Streams 28, 29, 31,
33, 34, 36, 37, 38, 40 and 41 will also be crossed on structure and
notwithstanding their potentially lower ecological value, will not be subject
to direct impacts.
8.7.11.2 For steams with
existing bridges or culverts, it will be necessary to undertake bridge widening
or culvert widening and these works cannot be avoided. However, the streams which require these
works are on the whole streams classed as having low ecological value, with the
exception of streams 15 and 18 as discussed in Section 8.7.7 above. In addition, in accordance with the proposal
to protect streams of high ecological value as far as possible, but balance the
visual impacts of bridge structures, new culverts have been proposed for a
number of streams but these works have been restricted to streams of low
ecological value, with the exception of streams 19 and 21 where it is
unavoidable, as discussed above.
8.7.11.3 Streams 10, 11,
12 and 14 will have existing bridges widened, while existing culverts at
streams 1-9, 13 and 17 will be extended. The remaining streams will be placed
in new culverts. The details of these works is summarised above in Section
8.7.7 and further details provided in Section 6. Overall, less than 0.01ha of stream course will be lost as a
result of these works. These streams
have been rated as being of moderate conservation value, being characterised by
low discharge which does not support any fauna of conservation interest. Also,
habitat loss per water course is small, and is not expected to be a significant
impact.
Fragmentation
8.7.11.4 Most of these
streams are already fragmented to some degree, either by water capture for the
Cheung Sha catchwater or by diversion or culverting at the junction with the
existing Tung Chung Road. Further fragmentation of these streams is not
expected to cause significant impact, since no species of conservation concern
have been recorded.
Disturbance
8.7.11.5 Disturbance to
the streams is associated with siltation as a result of works within the stream
course and in-direct impacts associated with construction run-off. New culverts will be required for streams
crossed by the off-line section of the new road (streams 20 and 30) as
presented in Table 8.15. In all cases, the culverts will be built separately in
advance of any connection with the existing stream, as described for Streams
18, 19 and 21 above. Impacts associated
with suspended solids, again, will be limited to the period when the flow is
diverted. As the streams being
culverted already have a very low base flow and in many cases are dry for much
of the year, the opportunity for suspended solids to be transported downstream
is negligible. Notwithstanding, any
release of suspended solids would be expected to be localised as the material
settles out, as the period of works is of short duration, and as the streams do
not contain any species of conservation interest, impacts on the ecology are
considered to be insignificant.
8.7.11.6 There are four
existing small bridges (STR01 to 04 on the figures in Section 2) along the
on-line section of the roadworks, crossing streams 10, 11, 12, 14, in addition
to STR05 crossing stream 15 as described above, which need to be widened. The details of the widening works are
described in Section 8.7.7.15. As discussed, prior to these works commencing,
whatever flow is in the stream will be ponded by building a dam across the
stream, upstream from the works. A
temporary pipeline will then divert the stream water around the works area into
the unaffected downstream area. Based
upon this and the absence of species of conservation interest in these streams,
ecological impacts are considered to be insignificant.
8.7.11.7 Streams 1-9, 13
and 17 will require existing culverts to be extended. As with the requirement
for new culverts, the key potential disturbance impacts associated with these
works are the downstream run-off of suspended solids. The works will be limited
based upon the construction of the culverts in advance of its connection to the
stream as described from streams 18, 19 and 21 above. In addition, these streams have a low overall flow, works will be
undertaken when the flow is low and since there are no species of conservation
interest present, disturbance impacts such as siltation and destruction of
existing stream bed are anticipated to be insignificant.
8.7.12
Freshwater Marsh (Fong
Yuen)
8.7.12.1 No significant
habitat loss or fragmentation will ensue directly from the proposed
development, with the proposed permanent drainage pipeline and cycle path
passing close to the existing road alignment and being designed to avoid the
marsh completely, by a distance of 20m.
The road works will be some 60-70m at nearest point from the marsh.
Disturbance
8.7.12.2 Disturbance from
earth-moving works associated with
construction of a storm water sewer and cycle path above the marsh is not
expected to impact adversely on the important population of the Ricefish Oryzias curvinotus present in the marsh,
since drainage disruption will be avoided and run-off will be collected in a
concrete-lined trench before it can enter the marsh (see Section 6). Thus, no impacts are predicted on the Fong
Yuen Marsh.
8.7.13.1 This habitat
accounts for a total area of 23.0 ha within the Study Area. However, the
proposed road development will not encroach on this habitat. In view of this,
and the fact that Village Area in the Study Area was rated as being of low
ecological value, any impacts to this habitat, and to the species occupying it,
arising from the project are considered to be insignificant.
8.7.14.1 This habitat
accounts for a total area of 3.4 ha within the Study Area. However, the
proposed road development will not encroach on this habitat. In view of this,
and the fact that agricultural land in the Study Area was rated as being of low
ecological value, any impacts to this habitat, and to the species occupying it,
arising from the project are considered to be insignificant.
8.7.15.1 This habitat
accounts for a total area of 7.3 ha within the Study Area, of which 0.23 ha
will be permanently lost as a consequence of development. Owing to the small
scale of habitat loss, the highly fragmented nature of the habitat and its low
ecological value, any impacts to this habitat, and to the species occupying it,
arising from the project are considered to be insignificant.
8.7.16.1 The composition
of the terrestrial animal community is largely dependent on the floral
structure and species composition of the habitats present (Dudgeon and Corlett,
1994). The study area contains a large number of faunal species of conservation
interest, particularly species associated with freshwater habitats. There is a
concomitant requirement to preserve habitat integrity as a necessary
prerequisite for species conservation, in particular the narrow belt of
riparian vegetation, which is an important wildlife corridor. For individual
animal species, impacts (particularly construction phase impacts) generally
will be higher for species which have lower avoidance ability, either due to
having very specific habitat requirements or low locomotory capability, or
both. These factors are summarised in Table 8.28 below for the species of
conservation interest recorded in the Study Area. It should be noted that
larval stages of amphibians and odonates are potentially more vulnerable than
adults due to being confined to aquatic habitats.
Table
8.28 Summary of Habitat
Requirements, Mobility and Predicted Impacts on Faunal Species (Adults) of
Conservation Interest in the Study Area
Species |
Conserv-ation
Interest |
Remarks
and Impact Evaluation (see Tables 8.29 and 8.30) |
Locations
recorded |
Melogale moschata (Ferret Badger) |
High |
Fairly broad
habitat tolerance. Moderate to high mobility. Minor impact from road barrier effect |
Dead on Tung
Chung Road at 150m, (HE 030643), in shrubland habitat |
Centropus sinensis (Greater Coucal) |
Moderate |
Very broad habitat tolerance. High mobility. Insignificant
impact |
Plantation woodland at numerous locations along Tung
Chung Road, around Pak Kung Au and near Cheung Sha |
Centropus bengalensis (Lesser Coucal) |
Moderate |
Fairly broad habitat tolerance. High mobility. Insignificant
impact |
Tall shrubland/ shrubland-grassland mosaic at
numerous locations along Tung Chung Road, around Pak Kung Au and near Cheung
Sha |
Caprimulgus indicus (Grey Nightjar) |
High |
Fairly broad habitat tolerance. High mobility. Insignificant
impact |
Tall shrubland/ shrubland-grassland mosaic near the
AFCD Management Centre |
Psammodynastes
pulverulentus (Mock Viper, snake) |
Moderate |
Fairly narrow habitat tolerance. Moderate mobility. Insignificant
impact |
Plantation woodland beside Cheung Sha catchwater,
120m (grid square 0461) |
Naja atra (Chinese Cobra, snake) |
High |
Fairly broad
habitat tolerance. Moderate mobility. Insignificant impact |
Shrubland,
streams at Shek Mun Kap and Stream Nos. 23 and 40 |
Ptyas korros (Indochinese Rat Snake) |
Moderate |
Fairly broad habitat tolerance. Moderate mobility. Insignificant
impact |
Plantation woodland (catchwater) (previous record) |
Paramesotriton
hongkongensis (Hong Kong Newt) |
Very High |
Narrow habitat tolerance. Low mobility. Minor to moderate impact from culverting of stream 19 and
road barrier effect |
Stream No.’s 15, 19 |
Megophrys brachykolos (Short-legged Toad) |
Very High |
Narrow habitat tolerance. Low to moderate mobility. Minor to moderate impact from road barrier effect |
Tung Chung Stream, Stream No.’s 24, 26, 32, 35, 40, 42 |
Rana exilispinosa (Lesser Spiny Frog) |
High |
Narrow habitat tolerance. Low to moderate mobility. Minor to moderate impact from culverting of stream 21 |
Tung Chung Stream, Stream No.’s 18, 21, 23, 24, 25,
26, 27 |
|
|
|
|
Philautus romeri (Romer’s Tree Frog) |
Very High |
Fairly narrow habitat tolerance. Low to moderate
mobility. Minor to moderate impact on breeding sites from tall
shrubland loss between Lung Tseng Tau and Pak Kung Au, and from culverting of
stream 21 |
Secondary woodland at Shek Mun Kap and Lung Tseng
Tau, plantation woodland and tall shrub at Pak Kung Au, Tung Chung Stream and
stream Nos. 21 and 27 |
Acrossocheilus wenchowensis
beijiangensis (Beijiang Thick-lipped Barb, fish) |
Very High |
Narrow habitat tolerance. Low mobility. Insignificant impact due to avoidance of major works
at streams where present |
Tung Chung Stream, Stream 15 |
Parazacco spilurus (Predaceous Chub) |
Low |
Narrow habitat tolerance. Low mobility. Insignificant
impact due to avoidance of major works at streams where present |
Tung Chung
Stream |
Awaous melanocephalus (Black-headed Thick-lipped Goby, fish) |
High |
Narrow
habitat tolerance. Low mobility. Insignificant
impact due to avoidance of major works at streams where present |
Cheung Sha
Stream, Stream 40 |
Stiphodon atropurpureus (Philippine Neon Goby, fish) |
High |
Narrow habitat tolerance. Low mobility. Insignificant impact due to avoidance of major works
at streams where present |
Tung Chung Stream, Cheung Sha Stream, Stream 40 |
Oryzias curvinotus (Ricefish) |
Very High |
Narrow habitat tolerance. Low mobility. Insignificant impact due to avoidance of any works
in Fong Yuen Marsh |
Fong Yuen Marsh |
Agriomorpha fusca (Damselfly) |
High |
Narrow habitat tolerance. Low to moderate mobility. Insignificant impact due to avoidance of major works
at streams where present |
Stream No.’s 26, 27 |
Drepanosticta hongkongensis (Damselfly) |
Very High |
Narrow habitat tolerance. Low to moderate mobility. Insignificant impact due to avoidance of major works
at streams where present |
Stream No.’s 26, 27 |
|
|
|
|
Leptogomphus elegans
hongkongensis (Dragonfly) |
High |
Fairly narrow habitat tolerance. Moderate to high
mobility. Insignificant impact due to avoidance of major works
at streams where present |
Shrubland, stream No. 23 |
Melligomphus moluami (Dragonfly) |
Very High |
Fairly narrow habitat tolerance. Moderate to high
mobility. Insignificant impact due to avoidance of major works
at streams where present |
Shrubland, Tung Chung Stream, stream No.’s 23, 25,
26, 27, 32 |
Protosticta beaumonti (Damselfly) |
Very High |
Narrow
habitat tolerance. Low to moderate mobility. Insignificant
impact due to avoidance of major works at streams where present |
Stream No.’s 24, 26, 27, 32, 35, 40, 42 |
Sinosticta ogatai (Damselfly) |
Very High |
Narrow habitat tolerance. Low to moderate mobility. Insignificant impact due to avoidance of major works
at streams where present |
Stream No.’s 26, 27 |
Stylogomphus chunliuae (Dragonfly) |
High |
Fairly narrow habitat tolerance. Moderate to high
mobility. Insignificant impact due to avoidance of major works
at streams where present |
Stream No.’s 27, 32 |
Zygonyx iris insignis (Dragonfly) |
High |
Fairly narrow habitat tolerance. Moderate to high
mobility. Insignificant impact due to avoidance of major works
at streams where present |
Shrubland, Tung Chung Stream, stream No’s 35, 41 |
Pelopidas subochracea (Large Branded Swift, butterfly) |
Moderate |
Fairly broad habitat tolerance. Moderate to high
mobility. Insignificant impact as no destruction of larval
foodplant |
Secondary woodland at stream 40, 50m |
Telicota colon (Pale Palm Dart, butterfly) |
Moderate |
Fairly broad habitat tolerance. Moderate to high
mobility. Insignificant impact due to no destruction of major
larval foodplants |
Fong Yuen Marsh |
|
|
|
|
Pachliopta aristolochiae (Common Rose, butterfly) |
Moderate |
Fairly broad habitat tolerance. Moderate to high
mobility. Insignificant impact due to no destruction of major
larval foodplants |
Secondary woodland, near stream 8. Secondary
woodland Cheung Sha Sheung Tsuen, 50m |
Eurema brigitta (Small Grass Yellow, butterfly) |
Moderate |
Fairly broad habitat tolerance. Moderate to high
mobility. Insignificant impact due to no destruction of major
larval foodplants |
Tall shrubland, 60m, HE 0265. Plantation woodland at
catchwater (100m, HE 0462), shrubland (120m, HE 0264) |
Jamides celeno (Pale Cerulean, butterfly) |
Moderate |
Fairly broad habitat tolerance. Moderate to high
mobility. Insignificant impact due to no destruction of major
larval foodplants |
Secondary woodland and tall shrub at Shek Mun Kap,
plantation woodland and shrubland at 150m, HE 0362 |
Athyma ranga (Blackveined Sergeant, butterfly) |
Moderate |
Fairly broad habitat tolerance. High mobility. Insignificant impact due to no destruction of major
larval foodplants |
Plantation woodland, stream 27, 360m |
Euthalia lubentina (Gaudy Baron, butterfly) |
Moderate |
Fairly broad
habitat tolerance. High mobility. Insignificant
impact due to no destruction of major larval foodplants |
Secondary
woodland at Shek Mun Kap, 30m |
Moduza procris (Commander,
butterfly) |
Moderate |
Fairly broad habitat tolerance. High mobility. Insignificant impact as no destruction of larval
foodplant |
Plantation woodland (340m, HE 0363) |
Note : Grid references based on Countryside Series Map of Lantau, 2nd Edition. Grid references are provided on Figures 8.14 to 8.18.
8.7.17
Slope remediation works on
obsolete sections of existing Tung Chung Road
8.7.17.1 The proposed
slope upgrading works that may generate only limited ecological impacts
associated with minor slope trimming works which could result in the removal of
some existing shrub vegetation.
However, shotcrete removal, soil nailing and rock slope stabilisation
measures for rock slopes could also be a source of dust which could affect
local flora and fauna. Noise generated for the duration of the works could also
cause disturbance to wildlife.
8.7.17.2 In these cases,
as no major slope regrading will be undertaken, the dense vegetation at the top
of the slopes will largely be undisturbed although the removal of some
vegetation in the form of shrubland may be required, but the mature trees will
be retained. In view of the small extent of slope works required, the woodland
and tall shrubland habitats on the whole would not be adversely impacted. As
these types of habitat are common throughout Hong Kong and the habitats are
currently subject to frequent disturbance, the overall short-term ecological
impacts of construction is considered to be insignificant.
8.7.17.3 In view of the
frequent human disturbances generated by the slope maintenance works and the
traffic on Tung Chung Road and no rare wildlife was recorded on these
artificial habitats, impacts are insignificant. Also, as the works will be of
only short duration and the area to be affected is situated within marginal
habitats, only minor disturbance to bird species and other wildlife is
expected. In addition, the fauna is mobile and will have the large
remainder of the country parks to go into in order to remove themselves from
the noise source in the short term.
8.7.17.4 In terms of
habitat loss, as the area of vegetation to be removed is considered marginal
and already disturbed, no significant impacts due to habitat loss are
predicted.
8.7.18
Night-time Working
Activities
8.7.18.1 It is likely that
the proposed works will be undertaken up to 11.00pm and also on public holidays
in order to condense the works programme. Although there are relatively few
studies that have quantified the effects of disturbance on wildlife, there is
evidence to suggest that birds (Hill et al., 1997) and mammals such as deer are
prone to disturbance associated with human activity (English Nature, 1994).
Disturbance impacts are difficult to quantify as many species appear to
habituate to disturbances (Treweek, 1999).
Hill et al. (1997), however, discussed gradients of responses to
disturbance impacts in birds. They concluded that depending on the intensity,
frequency and duration, disturbance impacts were greatest during high-intensity
activity (especially high amplitude 'startling' noises associated with activity
such as shooting).
8.7.18.2 There is also
potential for disturbance impacts due to night working on other faunal groups
that are nocturnal such as the herpetofauna. As mentioned above for the more
readily studied faunal groups such as birds and mammals, although there does
not appear to be any studies that have quantified the effects of nocturnal
disruption, there is still the possibility that disturbance could affect
species such as frogs and toads. There
is for example, the potential for a reduction in the breeding success due to
mating calls being drowned out by loud noises during construction from the
operation of noisy machinery. There is also the possibility that such
disturbance will cause the frogs to delay their breeding activities until after
the disturbance has ended, i.e. after 11.00pm. Thus the length of time
available for breeding will be curtailed. These are, however, worst-case
scenarios and it is likely that noise will be within tolerable levels from
6.00pm to 11.00pm and the disturbance caused by evening working is considered
to represent an insignificant impact to herpetofauna.
8.7.18.3 It is considered
that continuous work activity would induce the greatest impacts to populations
of animals that form metapopulations (sub-populations), as a permanent barrier
created by the works area is likely to prevent inter-breeding between groups
either side of the construction site, thereby potentially impacting faunal
groups at the population level. Disturbance pressures are likely to be greater
in nocturnal species (most mammals and certain birds) that are unaccustomed to
pressures such as high levels of noise, artificial lighting and human activity
whilst foraging at night. Construction impacts based on working hours that have
breaks, however, as is proposed, are ecologically less severe as they allow
windows where mobile fauna can disperse between adjacent areas of habitat
(necessary for important ecological processes such as foraging, migration and
breeding) and the periods at dawn and during the middle of the night are likely
to be important for such activities. It should also be noted that the area
where evening work is likely to occur, due to the need to aviod impacts on
local residents, is reasonably restricted (from north of the WSD reservoir on
the existing Tung Chung Road to opposite the treatment works at the Catchwater)
and this will not lead to a continuous barrier of disturbance for the full
length of the construction area. As such, a permanent night-time barrier is not
anticipated and insignificant ecological impacts are predicted.
8.7.18.4 In summary,
working up to 11.00pm, but ceasing work between 11.00pm and 7.00am, is
considered a sufficient window to allow nocturnal species such as mammals,
birds and herpetofauna time for dispersion between habitats. Such rest-breaks
are particularly important to noise-sensitive fauna such as mammal and birds.
There is also likely to be an overall ecological gain from extending the
working hours to 11.00pm, as this will shorten the construction period. Based upon this, extending the works up
until 11.00pm is not predicted to give rise to additional significant impact to
fauna in the study area. The mitigation of impacts from construction activities
recommended in the EIA for day-time activities should ensure that the impacts
are at an acceptable low level during the evening-night period also.
8.7.19
Summary of Construction
Phase Impacts
8.7.19.1 A summary of
construction phase unmitigated impacts arising from the project is given in
Table 8.29 below. Significant impacts, requiring mitigation, are numbered for
easy reference in the ensuing discussions.
General Impact |
Specific Impact |
Impact No. |
Severity |
Mitigation |
Habitat
Loss |
Loss of 2.25 ha of high value secondary woodland Loss of 5 ha of plantation woodland Loss of 6.5 ha of tall shrubland Loss of 1 ha of shrubland-grassland
mosaic Loss of 0.1ha of stream course |
CPI1 CPI2 CPI3 |
Moderate Minor Minor-moderate Insignificant Insignificant |
Required Required Required Not required Not required |
Habitat Loss |
Reduction of nectar sources for
butterflies Secondary woodland loss at Lung Tseng
Tau affecting Romer’s Tree Frog Secondary woodland loss impacting on
forest-associated avifauna Flora of conservation interest,
including the tree Artocarpus
hypargyreus, the shrub Pavetta
hongkongensis and the orchids Acampe
rigida and Liparis viridiflora
directly impacted by loss of plantation & secondary woodland Tall shrubland loss impacting on
mammals, shrub-associated avifauna and dragonflies of conservation interest Secondary woodland and tall shrubland
loss impacting on Romer’s Tree Frog breeding sites (chainage 1.000 to 4.500)
Lung Tseng Tau to Pak Kung Au Loss of streambed and riparian
vegetation in streams 15, 18, 19 and 21 |
CPI4 CPI5 CPI6 |
Insignificant Insignificant Insignificant Minor Insignificant Minor-moderate Minor |
Not required Not required Not required Required Not required Required Required |
Fragmentation |
Fragmentation of plantation woodland
close to stream 27 where Romer’s Tree Frog present Fragmentation of tall shrubland habitat Culverting of streams 18, 19 and 21 Extension of barrier and isolation of
Beijiang Thick-lipped barb in stream 15 Stream modification works of other
streams |
CPI7 |
Insignificant Insignificant Minor Insignificant Insignificant |
Not required Not required Required Enhancement(1) Not required |
Disturbance |
Disturbance
to butterfly and dragonfly species of conservation interest Disturbance
to mammal and reptile species of conservation interest Disturbance
(noise, increased human activity) to birds Disturbance
(earth moving works) to Romer’s Tree Frog between Lung Tseng Tau and Shek Mun
Kap Siltation
of streams Siltation
of Tung Chung Bay Disturbance
of stream bed and riparian vegetation at streams 15, 18, 19 and 21 impacting
aquatic fauna Disturbance
of stream bed and riparian vegetation at other modified streams Disturbance
(earth moving works; drainage disruption) at Fong Yuen Marsh impacting
Ricefish |
CPI8 |
Insignificant Insignificant Insignificant Moderate Insignificant Insignificant Insignificant Insignificant Insignificant |
Not
required Not
required Not
required Required Not
required Not
required Not
required Not
required Not
required |
Note: 1The road project will
not significantly increase fragmentation of stream 15 and lead to greater
isolation of Beijiang Thick-lipped Barb although in order to increase the
population viability of the species in the Tung Chung Stream catchment as a
whole, enhancement measures are recommended for stream 15 (see Section 8.9).
8.8
Operation Phase Unmitigated Impacts
8.8.1
General
8.8.1.1 Operational phase
impacts are related to impacts associated with vehicles and include disturbance
(noise and increased human activity), barrier effects, vehicular collision and
pollution. These potential impacts are discussed further in the sections below.
8.8.2.1 Disturbance
impacts incurred during the operational phase are associated with elevated
noise levels, presence of vehicles and overall higher contact with associated
human activities. Noise levels associated with vehicles rather than visual
impacts (perceived threats from moving vehicles) are, however, considered to be
the main cause of impact to wildlife species. Territorial species are also
known to be more affected by road projects than species that roam over wide
areas (Reijnen et al., 1995).
8.8.2.2 It should be
noted, however, that many faunal groups are known to habituate to disturbance
including elevated noise. Much of the northern part of the Study Area (chainage
1.000 to 4.500, Figures 2.2 to 2.7) is already occupied by the existing Tung
Chung Road, which has been in place for several decades.
8.8.2.3 Noise levels
associated with vehicles rather than visual impacts (threats) are considered to
be the main cause of reduced breeding populations of woodland bird species
adjacent to major road schemes (Reijnen et
al., 1995). Some territorial bird species are known to show lower breeding
densities adjacent to roads such as motorways. However, other species show
higher densities closer to roads, although this may be an indirect effect due
to different roadside vegetation (Reijnen et
al., 1995). As discussed for the construction phase impacts, although the
effects of disturbance on birds are difficult to quantify, many bird species in
Hong Kong (and elsewhere) are known to habituate to disturbance including elevated
noise. Noise levels due to traffic flow are not considered to represent a
significant impact. Overall, passive low-level continuous disturbance is better
tolerated than active high-level continuous disturbance and furthermore, birds
are known to tolerate vehicles and vehicular movement better than people as a
source of disturbance (Hill et al,
1997). Operational phase disturbance impacts are, therefore, predicted to be
insignificant to avifauna present.
8.8.2.4 Mammal species
such as Barking Deer, Ferret Badger, Civets, and Leopard Cat are sensitive to
noise and visual disturbance and generally avoid noisy areas. These animals
are, however, primarily active at night, during which time noise associated
with the road is likely to be significantly lower due to reduced traffic
volume. Visual disturbance from large moving vehicles is also reduced at this
time. It is therefore considered that the impact of noise and visual
disturbance on the foraging behaviour of larger mammals will be insignificant.
8.8.2.5 Noise is not generally
considered to cause disturbance to herpetofauna, which tend to be more reliant
upon vision or smell for foraging and communication purposes. However, breeding
frogs and toads are highly reliant upon auditory communication (i.e., male
breeding vocalisations), and it is possible that noise disturbance from the
road will have an impact on breeding success of amphibians such as Romer’s Tree
Frog, Short-legged Toad and Lesser Spiny Frog in locations proximal to the
road. It should be noted, however, that such breeding behaviour is primarily
conducted at night, when traffic noise is lower, and that the road will impinge
upon a relatively small proportion of the available breeding habitat (streams;
moist shady woodland) in the Study Area. It is therefore anticipated that this
impact will be insignificant.
8.8.2.6 Noise disturbance
from the road will likely have no impact upon the behaviour of insects or fish.
It is possible, however, that the visual perception of moving vehicles will
have an impact on foraging or day-time perching behaviour of butterflies and
dragonflies. These insects are easily unsettled by movement of large objects
such as people or vehicles. Owing to the high mobility of these taxa, however,
and the small area (relative to available habitat) occupied by the road, this
impact is considered to be insignificant.
8.8.3.1 The effect of
linear developments such as roads that form barriers to wildlife populations
are well documented (English Nature, 1994; Treweek, 1999). Many animals are reluctant
to cross structures such as roads and they can act as an effective barrier
preventing migration between adjacent habitat. A secondary effect related to
road operation is the turbulence caused by moving vehicles as many smaller
birds are unable to successfully traverse whilst vehicles are passing at high
speed without being killed (Treweek, 1999). Most birds are highly mobile,
however and the barrier-effect on most species is probably related to vehicle
density and speed. Given the relatively low vehicle numbers and vehicle speeds
(50 kph) on the Tung Chung Road, there is, therefore, not expected to be a
significant barrier effect on any of the bird species present in the Study Area
and the potential road operational impacts are considered to be insignificant.
8.8.3.2 Larger mammal
species may find the road a physical barrier to movement, although it is only
two lanes wide, as an 0.8m high parapet will be constructed on the west side of the road on all retaining walls,
which may themselves reach a maximum height of 8m. Also, at times of high
traffic flow the road may effectively operate as a barrier due to noise and
visual impacts (see above) which induce deliberate avoidance of the road
(thereby cutting off the access to habitats on the other side of the road).
These impacts are considered minor since most larger mammal activity occurs
nocturnally, when traffic flow on the road will be lower. There will also be
numerous elevated structures along the road which would serve as corridors to
allow mammals to avoid having to cross the road. Also, it should be noted that
very few records of large mammal species were obtained during the survey period
(May 2001 to January 2002).
8.8.3.3 Herpetofauna are
physically able to cross roads provided that barrier walls have not been constructed.
However, as noted above, an 0.8m parapet will be in place along much of the
road. Also, roads are highly exposed habitats and it is possible that some
cryptic species (e.g. Short-legged Toad, Romer’s Tree Frog) would avoid the
road as a consequence. The road may therefore effectively act as a barrier to
movement of such species between areas of suitable habitat bisected and
fragmented by the road. This impact is considered to be minor to moderate in
view of the fact that the road will have numerous bridges which would allow
herpetofauna to cross safely beneath the road.
8.8.3.4 Herpetofauna of
low mobility such as Short-legged Toad, Hong Kong Newt and Romer’s Tree Frog
may be impacted by tumbling into U-shaped concrete drainage channels on and at
the base of cut slopes. These channels are typically steep and smooth-sided and
therefore present a physical barrier to these species. This impact is
considered minor.
8.8.3.5 Although the road
itself will not create a barrier effect for freshwater fish, fish access within
streams may be impeded by channels/culverts constructed at points where the
road intersects with such streams. Many culverts and channels constructed for
the existing Tung Chung Road incorporate high vertical drop-offs which present
a barrier to upstream movement for fully aquatic fauna, such as fish, located
downstream of these structures. This may have knock-on effects for breeding and
foraging success, and population viability. Streams of high conservation value
which may be impacted in this way include No.’s 19 and 21. However, fish
species of conservation interest were not recorded in these streams. This
impact is, therefore, considered insignificant. Similarly, existing culverts (concrete lined bridge) will be
widened at streams 15 and 18 and these existing structures already exert a
barrier effect and the extensions to both structures will not incur a
significant additional impact.
8.8.4
Mortality due to Physical
Impact with Vehicles
8.8.4.1 There are few
examples present in the literature that describe the impacts of vehicles on
bird populations due to direct physical impacts. The potential for physical
impact is especially high where new road projects bisect routes used for
activities such as foraging or pathways used for roosting. Birds of prey
particularly owls (Reijnen et al.,
1995) and probably hawks appear to be particularly susceptible to collision
with fast moving vehicles as they often forage along roadsides that provide
areas of suitable habitat for their small mammal prey species. Conversely, although evidence is
fragmentary, carrion feeders such as crows and magpies may increase in numbers
due to the presence of vehicle-killed birds (Reijnen et al., 1995).
8.8.4.2 It has been
estimated that bird casualties on roads, mainly motorways, in Europe can vary
from between 5000 to 70 million individuals per year (Treweek, 1999), although
it is difficult to determine accurately the exact number killed by physical
impacts with vehicles. The data available also requires certain caveats as not
all roads have traffic travelling at the same speed or traffic density and it
is likely that wider roads such as motorways are more difficult to pass than
narrower single-lane roads thereby leading to proportionally lower number of
casualties in the latter.
8.8.4.3 Also, it is generally
assumed that increases in mortality due to road traffic are too small to cause
significant decreases in population size and reduction in woodland bird species
present is often related to noise impacts (Reijnen et al., 1995). Although the potential for physical impact is
persistent, owing to the high mobility of the bird species present, operational
impacts are considered to be insignificant.
8.8.4.4 Many species of
herpetofauna are susceptible to impacts with motor vehicles when crossing roads
during migration to breeding sites (e.g. Hong Kong Newt, which has been
observed crossing roads in the New Territories (G.T. Reels, pers. obs.) or
whilst foraging (e.g., snakes and lizards). Many herpetofauna species are
slow-moving and slow to initiate an avoidance response to approaching vehicles.
Many of these exothermic taxa (notably snakes) also actively seek out exposed
and sun-heated road surfaces for basking. It is also the case that many
motorists coming across snakes or other herpetofauna on the road either do not
notice them or do not try to avoid impacting them. During surveys conducted for
the current project, one dead Changeable Lizard and one dead Greater Green
Snake were observed on the existing Tung Chung Road. Both had presumably been
killed by passing vehicles. However, the new road will replace the old road
rather than adding to it, and since it is of approximately equal length, has
fewer blind corners and passes through broadly similar habitat, it is likely
that the net increase in road mortality impact will be insignificant.
8.8.4.5 Larger mammal
species are generally agile, and able to perceive approaching vehicles and make
an avoidance response before collision. Such animals are also easier to detect
than herpetofauna for the oncoming motorist. Impacts do occur, however, and a
dead Ferret Badger was observed on the existing Tung Chung Road in October 2001
(north of Pak Kung Au). It should be noted that this is a rare occurrence in
the Study Area, due to the scarcity of large mammals present, although it may
be argued that this scarcity makes such road mortality all the more
significant. In this context it should also be noted that Ferret Badger is a
secretive species, thought to be under-recorded in Hong Kong (Reels, 1996), and
may therefore be less scarce in the Study Area than previously thought (it
appears likely that the individual found dead on Tung Chung Road was the first
Lantau record for this species). In view of this, and because of the current
and long-established existence of the Tung Chung Road, additional road
mortality impact on larger mammals during operation of the new road is
considered to be insignificant.
8.8.4.6 Impacts on
dragonflies and butterflies due to road mortality are insignificant. Most
species do not utilize this habitat and are at any rate highly mobile and able
to avoid direct collisions, although air turbulence from passing vehicles may
represent a hazard. The ubiquitous dragonfly Pantala flavescens does occasionally show swarming behaviour along
horizontal road surfaces, apparently mistaking them for slow-moving rivers, and
may incur massive mortality from passing vehicles in the process (G.T. Reels,
pers. obs.), but this species is abundant in Hong Kong and elsewhere in the
region.
8.8.5
Pollution Emission from
Vehicles
8.8.5.1 Pollution impacts
from road traffic can affect the abundance of insect prey available to birds.
Vehicle emissions could potentially have impacts on the availability of food
and hence reduce breeding bird populations (Reijnen et al., 1995). Vehicle emissions also have the potential to induce
toxic responses in bird populations inhabiting roadside habitats. Both
reduction in insect populations and presence of pollutants are known to be
highly localised impacts, however (Reijnen et
al., 1995), and they are not considered to represent a significant
operational phase impact to the avifauna of the Study Area. As there is only
predicted to be relatively low number of vehicles using the road each day, the
emissions from vehicles on bird populations is considered to be insignificant.
This comment also applies to other terrestrial fauna in the Study Area.
8.8.5.2 Rainwater run-off
which has been contaminated by contact with vehicular deposits (such as engine
oil, coolant and petroleum fumes) on the road surface may potentially cause a
pollution impact, if it enters streams and other watercourses, on benthic
invertebrates and on the taxa (fish, tadpoles, odonate larvae) which predate
them (CIRIA, 1994). However, all road run-off from the proposed road will be
collected via a specially designed carrier pipe and discharged at either end of
the alignment into the Wong Lung Hang nullah and an outfall at Pui O Wan. Thus, no run -off into adjacent streams will
occur. In view of the interception of run-off this impact is considered
insignificant.
8.8.5.3 Accidental
spillage of oil or chemicals from an overturned tanker truck may potentially
have a severe impact on stream communities.
However, the deletion of hair-pin bends on the road should combine to
make this a remote possibility. In addition, the road parapet proposed along
large sections of the road will prevent vehicles from leaving the road and the
permanent drainage pipeline beneath the road will facilitate containment of any
spills and diversion away from the streams. A spill response plan will also be
implemented as specified in section 6.
8.8.5.4 Notwithstanding
it is possible for some of the spilled material to be transferred along the
operational carrier pipe and be discharged either in the nullah in Tung Chung
or Pui O Wan. It should be noted, however, that the refined oils carried by
tankers in Hong Kong although toxic and can cause localised damage when
spilled, are likely to disperse quickly. Owing to the relatively high
volatility of light oils, fast flowing waters are known to recover rapidly (weeks
to months) from spills (Abel, 1996).
However, based upon the fact that, for the northern section of the road,
any spill would ultimately end up in Tung Chung Bay which contains the San Tau
SSSI seagrasses and mangroves, an oil interceptor will be provided for
treatment of the road runoff prior to
its discharge into the Wong Lung Hang nullah.
This will have the effect of minimising the impacts by containing the
oil. The emergency response plan and
the provision of an oil interceptor are considered to be sufficient to reduce
impacts to acceptable levels.
8.8.6
Summary of Operational
Phase Impacts
8.8.6.1 A summary of
operation phase unmitigated impacts is given in Table 8.30 below. Significant
impacts, for which mitigation is required, are numbered for easy reference in
the ensuing discussions.
General
Impact |
Specific
Impact |
Impact
No. |
Severity |
Mitigation |
Disturbance |
Traffic
noise and visual impact affecting foraging and / or breeding behaviour of
fauna of conservation interest |
|
Insignificant |
Not
required |
Barrier Effects |
Barrier
effect of road on avifauna Barrier
effect of road on larger mammals Barrier
effect of road on herpetofauna Barrier
effect of U-shaped drainage channels on herpetofauna Barrier
effect of culverts on fish (notably streams 19 and 21) |
OPI1 OPI2 OPI3 |
Insignificant Minor Minor-moderate Minor Insignificant |
Not
required Required Required Required Not
required |
Mortality due to impact with vehicles |
Mortality
incurred by avifauna, larger mammals, herpetofauna and insects as a
consequence of collisions with vehicles |
|
Insignificant |
Not
required |
Pollution Emission from vehicles |
Toxic
effects of vehicle exhaust fumes on arthropods and vertebrates which predate
them Run-off
of contaminated rainwater from road into streams Spillage
of oil or chemicals into streams due to leakage from overturned tanker lorry |
|
Insignificant Insignificant Insignificant |
Not
required Not
required Not
required |
8.9
Impact
Mitigation Measures
8.9.1
Construction Phase Impact Mitigation
General
8.9.1.1 The problem of
improper spoil disposal is avoidable. Any spoil should be handled, transported
and disposed of in accordance with recommendations in Chapter 7. A ticketing
system will be used so that the site supervisor can control and keep track of
all movements of spoil.
8.9.1.2 Accidental or
other intrusion of construction activities beyond the designated works area can
also be avoided. The works area boundary should be defined throughout using
lightweight but weather-resistant material, such as a low shadecloth barrier.
No activities, including casual disturbance, vehicle parking and temporary
storage should be tolerated outside the
defined boundary.
Habitat Loss
8.9.1.3 Significant (>
1 ha) habitat losses will be incurred in the following habitats: secondary
woodland, plantation woodland, tall shrubland (CPI1-3; Table 8.29). These
habitats have been determined to have moderate to high ecological value (Tables
8.16, 8.17 and 8.18). Losses are incurred along the road alignment and on cut
slopes on the roadside, as well as at the bus lay-by facility at San Shek Wan,
the cycle track at Lung Tseng Tau and the drainage pipe to Pui O Wan. These
losses may be mitigated by compensatory planting.
8.9.1.4 All land
disturbed during the course of the works, that will not subsequently be
occupied by the permanent works, will be planted with either native woodland or
scrub species. As a general approach,
where these areas lie within or alongside areas of existing woodland then
woodland species will be planted. In
areas bordered by tall and low scrub, then appropriate scrub species will be
established.
8.9.1.5 The steepness of
slopes poses a constraint on the species that can be planted. Slopes with a gradient of more than 35
degrees would only be suitable for the establishment of small tree and tall
shrub species (not tall tree species). Slopes with a gradient of more than 45
degrees would only be suitable for the establishment of shrub species. Soil cut
slopes in excess of 55-60 degrees would not be suitable for the establishment
of woody vegetation, but would be hydro-mulched with grass, climbers and
groundcover species to provide a green appearance.
8.9.1.6 The limit of
disturbance has been contained as far as is practical to the alignment of the
new and widened carriageways. This
results in only a very limited amount of space for re-planting.
8.9.1.7 As the road is
bordered for the most part by scrub or woodland habitats, there are very few
opportunities for additional planting in areas outside the limit of
disturbance.
8.9.1.8 Additional infill
planting is also proposed in several open areas alongside the new or existing
road corridors, where existing low scrub vegetation would be enhanced with the
addition of native tree species.
8.9.1.9 In determining
the quantity of the compensation planting for ecological mitigation, reference
has been made to the area of land available for planting, and it's ability to
support different types of vegetation (especially restriction of tree planting
on steep slopes). Approximately 14.5ha of habitat will be lost as a result of
the Tung Chung Road Widening project and a general approach of providing
compensation planting more than the area lost has been proposed. Details of the planting are summarised in
Table 8.31 below. Details of the
species to be planted are provided in the mitigation proposals in Section 9 and
Appendix I.
Table 8.31
Summary of Planting Proposals
Planting Type |
Area (ha) |
Description |
Native
woodland planting |
12.0
ha |
Newly
formed slopes and reinstated disturbed areas alongside existing areas of
secondary woodland, plantation woodland or tall scrub. Grass hydro-seeding with native grass seed
mix and groundcover plants, with pit planting of native tree species at 1.5
metre centres |
Infill
planting |
12.5
ha |
Planting of native trees in
previously disturbed bare ground or areas of existing low shrub adjacent to
the road, to mitigate for loss of landscape resource and character, for
visual screening and to enhance ecological diversity. Estimated that some 2000 no.
new trees per hectare could be planted in this manner |
Grass
hydroseeding with Groundcover plants, or hydro-mulching |
0.55
ha |
Rehabilitation
of existing steep slopes by grass hydro-seeding with native grass seed mix
and groundcover plants or by hydro-mulching |
Individual
trees |
321
no.* |
Heavy
Standard trees planted in flat ground, or pavement tree pits alongside the
road |
Amenity
shrub planting |
0.4
ha |
Ornamental
shrub planting in planter beds alongside the road. |
TOTAL |
25.45ha |
|
*not included in area total
8.9.1.10 Existing man-made
slopes, such as those requiring remediation on obsolete sections of the
existing Tung Chung Road, should be restored using landscape treatment and
bio-engineering methods such as grasscrete and terracing following current Hong
Kong best practice as described in GEO (2000) to maximise opportunities for the
establishment of native woodland vegetation as far as possible.
8.9.1.11 To further offset
these losses on-site, cut slopes for the new road should be landscaped using
environmentally-sensitive bio-engineering measures as described in GEO (2000)
such as incorporating a ‘stepped’ design with soil in the resultant terraces to
facilitate establishment of vegetation. Native tree and shrub species should be
established, and grass slopes avoided where possible.
8.9.1.12 Where the new
road passes close to or over individual plants of protected floral species (as
at chainage 4.380, Pavetta hongkongensis,
Aceampe rigida and Liparis
viridiflora (protected under the Forests and Countryside Ordinance Cap.
96); and chainage 5.080, Artocarpus
hypargyreus (a Class III nationally protected species in China) (CPI4),
these individuals may be transplanted to safe locations within the same
habitat. However, since these species are all common in Hong Kong, the
ecological effect of their loss would be minor. Whilst there is not considered
to be a strong ecological reason for transplantation, a tree survey has been
conducted and will recommend transplantation of the individual plants
concerned. A translocation
specification is recommended to be prepared during the design phase of the
project and a design audit conducted to ensure it meets the requirements of the
EIA.
8.9.1.13 Romer’s Tree Frog
may be impacted by loss of secondary woodland and tall shrubland habitat
between Lung Tseng Tau and Pak Kung Au (CPI5). Breeding sites for this species
include small seepages close to streams. This impact can be mitigated by the
compensatory planting of woodland and shrubland. In addition, provision of alternative breeding sites, such as
water-filled pots placed on the ground at remote locations away from
disturbance would mitigate for the loss of habitat until the replacement
planting has matured. The main criterion for the pots is that predatory fish
are excluded. Such measures have been successfully tried and tested in Hong
Kong (Dudgeon and Lau, 1999). A specification for the pots is recommended to be
prepared during the design phase of the project and a design audit conducted to
ensure it meets the requirements of the EIA.
8.9.1.14 Four streams of
high ecological value, Streams 15, 18, 19 and 21, will be disturbed by
culverting activities. These will impact on the Hong Kong Newt and Beijiang
Thick-lipped Barb at Stream 15, Hong Kong Newt at Stream 19 and Romer’s Tree
Frog and Lesser Spiny Frog at Streams 18 and 21. These species have low mobility (Table 8.28) and impacts can be
minimised by evacuation and translocation of individuals of these species to
appropriate nearby locations. Such procedures should be conducted by an experienced
herpetologist in advance of works commencing in the impacted areas (CPI6). In addition, all works in these streams
should be avoided between April and June in order to avoid impacts during the
key breeding period for the Romer’s Tree Frog and Lesser Spiny Frogs, fish and
odonates. This period has been selected
on the basis that it covers the key breeding periods for the majority of
species of conservation interest recorded.
The exception to this is the Hong Kong Newt, which breeds between
September and March/April (pers. comm. M Lau), and although the latter month of
the Hong Kong Newt’s breeding season will be covered by this recommendation, it
is not practicable to limit the works for the whole period September to June. As such the period which would protect the
largest number of key species has been selected. Notwithstanding, impacts on the Hong Kong Newt are not expected
as this and other species will be translocated from the streams prior to the
works.
Fragmentation
8.9.1.15 Habitats within
the Study Area are already highly fragmented. Mitigation is, however,
recommended where the proposed road development incurs further fragmentation on
Streams 18, 19 and 21 (CPI7), since these are ecologically valuable habitats
(Table 8.20). Although no fish species of conservation interest were recorded
at these streams, the presence, albeit at low density, of other aquatic fauna
of conservation interest (Lesser Spiny Frog in Stream 18, Hong Kong Newt at
stream 19; Romer’s Tree Frog and Lesser Spiny Frog at Stream 21) means that
these streams have a high ecological value. The fragmentation caused by
construction of the culverts may be minimised by incorporation of
ecologically-sensitive designs, as illustrated in Figure 8.20a-c. The culvert
outlets should avoid a steep descending wall which is difficult for aquatic
fauna to negotiate and should incorporate a gentle rise with pooled areas.
Mitigation for culvert inlets and outlets (Figure 8.20a and 8.20c) is
applicable to all three streams. For the new culverts at Streams 19 and
21, the culverts are long (30m and 50m,
respectively) and should incorporate pooled areas where aquatic fauna can rest
and shelter (Figure 8.20b). No benefit
would be achieved by applying this technique to Stream 18 as the existing
culvert is present and would not be reconstructed.
8.9.1.16 Stream
fragmentation primarily affects obligate aquatic fauna such as fish. Stream 15
is already fragmented by a sheer rock wall upstream and a steep culvert exit
downstream and construction of the project will not increase this level of
fragmentation significantly. However, as the stream contains a small population
of Beijiang Thick-lipped Barb that is isolated from the rest of the Tung Chung
Stream and its tributaries (including nearby streams 19 and 21), it is proposed,
in order to enhance the viability of the population overall, that these fish in
Stream 15 may be captured and translocated downstream so that they can enhance
the main population of this restricted species in Tung Chung Stream.
8.9.1.17 This can be achieved
by the capture of the Beijiang Thick-lipped Barb in Stream 15 using a hand- net
and releasing them downstream of the existing bridge, which will enhance the
population in the Tung Chung stream of which Streams 19 and 21 are tributaries.
Disturbance
8.9.1.18 Disturbance is an
unavoidable impact of the road construction process. However, it will have
insignificant impacts on mobile taxa, or taxa which do not have highly specific
habitat requirements, such as birds, large mammals, most reptiles, and
butterfly and dragonfly adults, and in these cases disturbance impacts will be
avoided by ensuring that the works area is as small as practicable and kept
within well-defined limits, with shade-cloth shielding the works area, proper
spoil disposal and no intrusion into habitats beyond the works area boundary.
These considerations especially apply to streams with known high conservation.
8.9.1.19 The Romer’s Tree
Frog was also recorded in good numbers in secondary woodland (e.g., Lung Tseng
Tau, chainage 1.100 to 1.200; Shek Mun Kap, near chainage 1.700 to 1.800) and
tall shrubland (chainage 1.000 to 4.500) and, being a species of low mobility
(Table 8.28) will be impacted by disturbance from construction works
(CPI8). Impact avoidance is not
possible and thus, the impact may be mitigated by translocation of individual
frogs present at breeding sites on or adjacent to the road alignment. This includes areas of woodland and
shrubland on the east side of the road but also on the west above the Fong Yuen
Marsh. Such measures should be
conducted by an experienced herpetologist in advance of works commencing in the
impacted areas.
8.9.1.20 A summary of the
construction phase mitigation measures is provided in Table 8.32 below.
Table
8.32 Summary of Construction Phase
Impacts and Mitigation Measures
Impact |
Description |
Mitigation |
CPI1 |
Loss of 2.25ha of secondary woodland |
Restoration
of disturbed areas in accordance with the landscape proposal. Road width kept to
minimum to avoid habitat loss. Cut slopes for the new road
should be landscaped using environmentally-sensitive bio-engineering measures
as described in GEO (2000) such as incorporating a ‘stepped’ design with soil
in the resultant terraces to facilitate establishment of vegetation. Intensive
planting of native tree species at the bus lay-by facility site at San Shek
Wan and the Pui O Wan drainage channel. Intensive
and extensive replanting and enhancement (with appropriate native tree
species) along works area. Onsite and
off-site compensatory planting of about 25.5ha, which is more than the area
lost. |
CPI2 |
Loss of 5 ha of plantation woodland |
As above |
CPI3 |
Loss of 6.5 ha of tall shrubland |
As above |
CPI4 |
Flora of conservation interest,
including the tree Artocarpus
hypargyreus, the shrub Pavetta
hongkongensis and the orchids Acampe
rigida and Liparis viridiflora
directly impacted by loss of plantation woodland / secondary woodland |
Transplantation to
appropriate nearby location (to be determined during preparation of the
specification during the detailed design) |
CPI5 |
Secondary woodland and tall shrubland
loss impacting on Romer’s Tree Frog breeding sites (chainage 1.000 to 4.500) |
Provision of
water-filled pots in areas lost. Intensive planting of native tree species
along roadside between Lung Tseng Tau and Shek Mun Kap in accordance with the
landscape proposal as noted above |
CPI6 |
Loss
of stream bed and riparian vegetation at streams 15, 18, 19 and 21 impacting
aquatic fauna |
Evacuation and
translocation of Hong Kong Newt, Romer’s Tree Frog and Lesser Spiny Frog to suitable
adjacent sites by experienced herpetologist prior to works commencing. In addition, all works in
these streams should be avoided between April and June in order to avoid
impacts during the key breeding period. |
CPI7 |
Culverting of streams 18, 19 and 21 |
Culverts portals
and culverts designed so as to facilitate access/ passage by aquatic fauna
(such as ridged floor and incorporation of stone substrate see Figure
8.20a-b). Note that the incorporation of a ridged floor into the culvert
extension in Stream 18 would not serve any benefit as the existing culvert
will not undergo any reconstruction |
|
|
|
CPI8 |
Disturbance
(earth moving works) to Romer’s Tree Frog between Lung Tseng Tau and Shek Mun
Kap |
Evacuation of
Romer’s Tree Frogs by experienced herpetologist prior to works commencing. |
Enhancement
Measure |
Stream 15 |
Fragmentation of
Beijiang Thick-lipped Barb population isolated at nearby stream 15 alleviated
by evacuation of fish and release into Tung Chung Stream (of which 15, 19 and
21 are all tributaries) and incorporation of slope surfaces at step
channels for aquatic fauna to move up and down stream at the existing bridge
at stream 15 (see Figure 8.20c) |
8.9.2
Operation Phase Impact Mitigation
Disturbance
8.9.2.1 No significant
disturbance impacts are anticipated in the operation stage and thus no
mitigation is required.
Barrier
Effects
8.9.2.2 Barrier effects
are not significant for flying fauna such as birds, dragonflies and
butterflies, and are considered only minor for larger mammals (Table 8.29,
OPI1). Although the road will have numerous bridge crossings which will enable
mammals to safely negotiate the road and it may be possible for small mammals
such as Ferret Badgers to make use of wildlife tunnels. These will also be able to be used by
amphibians as discussed below. Wildlife
tunnels comprise relatively narrow (0.5m) tunnels that pass under the road.
8.9.2.3 Certain cryptic
herpetofauna, including species of high conservation interest such as Romer’s
Tree Frog and Short-legged Toad, may suffer minor-moderate impact due to
inability to cross because of the exposed nature of the road (OPI2). This
impact may be mitigated by construction of “wildlife tunnels” under the road in
appropriate locations.
8.9.2.4 It is only
possible to provide these tunnels in certain locations. It will not be
practical to provide wildlife tunnels under the new road in locations where the
road is bounded by a retaining wall on the uphill side of the road due to the
level difference between the natural ground behind the retaining wall and the
road. Any entrance behind the retaining wall would require a vertical shaft to
reach the tunnel under the road. Wildlife would unlikely be able to climb the
shaft, which would also attract debris and likely become blocked. However,
tunnels can be provided at 3 locations where there are few bridges as shown in
Figure 8.21. Based upon these and the provision of the bridges all along the
route, mammals and amphibians will have opportunity to traverse the road
safely.
8.9.2.5 Reptiles and
amphibians are particularly liable to fall into, and then be unable to escape
from, smooth, steep-sided concrete channels (such as those required for
drainage purposes on cut slopes). Romer’s Tree Frog, Short-legged Toad, Hong
Kong Newt and Chinese Cobra may all be impacted in this way (OPI3). Such
channels should be provided with regular “escape ramps” and/or natural breaks
such as exposed stable rock walls to permit these animals to climb out of the
channels. Such elements should be included in the EM&A Manual and should be
an integral element of the detailed design stage of the project. A conceptual
drawing is given in Figure 8.22.
Mortality due
to Physical Impact with Vehicles
8.9.2.6 No significant
impacts are anticipated as a consequence of animal mortality due to collision
with vehicles.
Pollution
Emission from Vehicles
8.9.2.7 No significant
impacts are anticipated from vehicle exhaust fumes or from run-off of
contaminated rainwater from the road into streams.
8.9.2.8 The risk of
pollution impacts from accidental chemical or oil spills from tanker trucks is
considered insignificant due to the robust road parapet, the incorporation of a
permanent road drainage system and the oil interceptor at Wong Lung Hang (see
Section 6).
8.9.2.9 A summary of
operational phase impacts and mitigation measures is provided in Table 8.33
below.
Table 8.33 Summary of
Operation Phase Impacts and Mitigation Measures
Impact |
Description |
Mitigation |
OPI1 |
Barrier
effect of road on larger mammals |
Construct “wildlife tunnels” under the road in appropriate locations (see Figure 8.21) |
OPI2 |
Barrier
effect of road on herpetofauna |
Construct “wildlife tunnels” under the
road in appropriate locations (see Figure 8.21) |
OPI3 |
Barrier effect of U-shaped drainage channels on herpetofauna |
Channels should be provided with
regular “escape ramps” and/or natural breaks such as exposed stable rock
walls to permit these animals to climb out of the channels (see Figure 8.22) |
8.10.1 The proposed mitigation measures are considered adequate to fully mitigate all of the identified impacts in the short term with the exception of woodland losses and the barrier effects of the road to mammals and herpetofauna, as discussed below.
8.10.2 Residual impacts after mitigation will remain for loss of habitat (CPI1-3) as this cannot be fully compensated in the short term. Initially residual impacts are expected to be moderate as the trees planted will be young and not capable of sustaining a large number of associated core woodland species. As the planting matures, particularly the planting in the existing plantation woodland which should continue to support faunal species, its value and ability to support species will increase and residual impacts will reduce to minor and then insignificant after a period of 15 to 20 years, when the woodland canopy will be mostly closed and suitable for colonisation by a range of faunal species. Table 8.34 provides an evaluation of the residual environmental impacts.
Table
8.34 Evaluation of Secondary Woodland
Residual Environmental Impacts
Residual
Impact Evaluation Criteria |
Secondary
Woodland |
Effect on public health
and health of biota or risk to life. |
Not
applicable key sedentary species of conservation interest will be
translocated in key areas |
Magnitude of Residual
Impacts |
Small
in relation to overall habitat present |
Geographic extent of
impacts |
Small
extent |
Duration of Impacts |
Permanent
loss of some habitat during life-time of the project although impacts are
moderate to insignificant (after ~ 20 years) |
Size of the environment
that may be affected |
Relatively
small in comparison to habitat present although relatively large in
comparison to the classification under the TM (maximum loss of 2.25ha; TM
classes >1ha as important) |
Reversibility of Impacts |
Reversible
although habitat will be replaced by planting a greater area of woodland in
other locations. Although the planted woodland will not function ecologically
the same as a mature woodland in the short-term, ecological function and
species compliment likely to be similar in the longer-term (ca. 20 years) |
Ecological Context |
Moderate
to high value |
International and
Regional importance |
Not
important either regionally or globally |
Certainty that impacts
will occur |
High |
Residual Impact |
Short-term Moderate, Medium-term Minor
and Long- term Insignificant |
8.10.3 Minor residual impacts of road barrier effects to mammals and herpetofauna (OPI1-2) will persist since mitigation measures (wildlife tunnels) cannot be applied along the entire length of the road. However, such impacts will be ameliorated to some extent by the presence of numerous elevated structures under which fauna may pass. Table 8.35 provides an evaluation of the residual environmental impacts.
Table
8.35 Evaluation of Barrier Effects of
the Road
Residual
Impact Evaluation Criteria |
Barrier
Effects of Road |
Effect on public health
and health of biota or risk to life. |
Not
applicable |
Magnitude of Residual
Impacts |
Low |
Geographic extent of
impacts |
6.2
km of road from Lung Tseng Tau to Cheung Sha |
Duration of Impacts |
Permanent
barrier effect during life-time of the project |
Size of the environment
that may be affected |
Not
applicable |
Reversibility of Impacts |
Irreversible
|
Ecological Context |
Species
of conservation interest may be isolated from adjacent habitat areas used for
foraging or breeding |
International and
Regional importance |
Insignificant
to minor |
Certainty that impacts
will occur |
Moderate |
Residual Impact |
Minor |
8.10.4 As discussed above, although some insignificant to minor residual impacts will occur these are considered to be acceptable within the overall benefits of the scheme.
8.10.5 A summary of the proposed mitigation measures and predicted residual impacts is provided in Table 8.36 below.
8.10.6
In addition to those recommended above
in Table 8.32 and Sections 8.7.7.19 and 8.7.7.20, the following mitigation
measures are applicable to this ecological assessment and were presented in
detail in the sections on Water Quality and Waste Management. The further
ecological mitigation measures comprise the following:
¨
areas in which works have been completed shall be restored
within 3 weeks of being completed in accordance with the Landscape Proposal
detailed in Appendix I;
¨
temporary cut slopes shall be covered with tarpaulin during
rainfall when not being worked to prevent erosion;
¨
major stockpiles shall be sited outside the Country Park and
away from stream courses;
¨
spoil heaps shall be covered at all times to minimise losses
in the wet season and reduce the dust emissions during the dry season to
minimise impacts on air quality;
¨
stock piled materials shall be contained in a designated
area down gradient from any stream or up gradient with a suitably constructed
barrier to reduce loss of materials to the stream; and
¨
sedimentation tank, oil interceptors and channels used
during the construction phase should be inspected every day rainfall is
recorded and weekly thereafter. The
sedimentation tanks and channels should be cleaned out when the volume of
settled sediments amounts to 10% of the total volume of the tank and the oil
interceptors should be cleaned when the volume of oil amounts to 50% of the
total volume of the oil interceptor.
Potential impact |
Potential mitigation measures |
Predicted
residual impact |
|||
Avoidance |
Minimising |
Compensation |
|||
On-site |
Off-site |
||||
CPI1-3 Habitat
loss impacting on secondary woodland, plantation woodland and tall shrubland |
Much of
the northern section of the proposed road (chainage 1.000 to 3.200) is online
with the existing Tung Chung Road, thereby substantially avoiding habitat
loss along this section. The road also incorporates a number of elevated
structures, particularly over streams of very high conservation importance. |
Restoration
of disturbed areas in accordance with the landscape proposal. Road width along its length kept to
minimum to minimise habitat loss. |
Cut slopes for the new road
should be landscaped using environmentally-sensitive bio-engineering measures
as described in GEO (2000) such as incorporating a ‘stepped’ design with soil
in the resultant terraces to facilitate establishment of vegetation. Intensive
planting of native tree species at the bus lay-by facilities site at San Shek
Wan and the Pui O Wan drainage channel. |
Intensive
and extensive replanting (with appropriate native tree species) along works
area. On-site and off-site
compensatory planting of about 25.5ha. |
Short
term low residual impact on habitats unavoidable since not all habitat loss
can be mitigated in the short term. However, loss of high ecological value
habitat minimised. No
residual impacts on Species of
Conservation Interest No
significant residual impacts from direct habitat loss on other habitats. |
CPI4 Four
plants of
conservation interest directly impacted by loss of plant-ation wood- land /
secondary woodland |
Unavoidable |
Transplantation
to appropriate nearby location |
Not
applicable |
Re-planting
at appropriate nearby location |
No
residual impact |
CPI5 Secondary
woodland and tall shrubland loss impacting on Romer’s Tree Frog (chainage
1.00 to 4.500) |
Unavoidable |
Not
applicable |
Intensive
planting of native tree species along roadside between Lung Tseng Tau and
Shek Mun Kap. Provision of water
filled pots as habitats for the Romer's Tree Frog. |
Not
applicable |
No
residual impacts |
CPI6 Loss of
streambed impacts on aquatic fauna by culverting activities at streams 15,
18, 19 and 21 |
Scheduling of the works in streams 15, 18, 19 and 21 to avoid the
period April to June which is the key breeding period for fish, amphibians
and odonates. |
Evacuation
and translocation of Hong Kong Newt, Romer’s Tree Frog and Lesser Spiny Frog
to suitable adjacent sites by experienced herpetologist prior to works
commencing |
Not
applicable |
Not
applicable |
No
residual impact |
CPI7
Fragmentation of streams 18, 19 and 21 due to culverting |
Unavoidable |
Culverts
and culvert exits designed so as to facilitate access by aquatic fauna |
Not
applicable |
Fragmentation
of Beijiang Thick-lipped Barb population isolated at nearby stream 15
alleviated by evacuation of fish and release into Tung Chung Stream (of which
15, 19 and 21 are all tributaries) |
No
residual impacts. |
CPI8 Disturbance
to Romer’s Tree Frog between Lung Tseng Tau and Shek Mun Kap |
Unavoidable |
Evacuation of Romer’s Tree Frogs by
experienced herpetologist prior to works commencing. |
Not
applicable |
Not
applicable |
No
residual impact |
OPI1-2 Barrier
effect of road on larger mammals and herpetofauna |
Large
number of new bridge structures proposed which will provide access. |
Construct “wildlife tunnels” under the road in appropriate locations. |
Not
applicable |
Not
applicable |
Minor
residual impact as mitigation cannot be applied along all stretches of road. |
OPI3 Drainage
channels traversing and at foot of cut slopes isolate herpetofauna of
conservation interest which fall into them |
Channels should be provided
with regular “escape ramps” and/or natural breaks such as exposed stable rock
walls to permit these animals to climb out of the channels |
Not
applicable |
Not
applicable |
Not
applicable |
No
residual impact |
8.11.1 It is stipulated that EM&A for ecology is undertaken during both the design, construction and operational phases of the project to ensure that all mitigation measures are fully complied with. In particular, the objectives of the design audit shall be to ensure that the design process clearly implements the design ecology mitigation specified in the mitigation Section 8.9 and to ensure that such designs are ecologically feasible and effective. The construction and operational EM&A objectives shall be to ensure that the ecological contract works and construction mitigation procedures recommended in Section 8.9 are carried out as specified and are effective. The construction and operational phase EM&A will be carried out as part of the site audit programme. Further details are provided in the EM&A Manual.
8.12.1 The Study Area traverses a large area of Country Park and contains a variety of habitats, of which the most ecologically valuable are streams, secondary woodland, mature plantation, tall shrubland and freshwater marsh. The Study Area is also floristically diverse and supports numerous faunal species of moderate, high, and very high conservation interest, many of which have a narrow habitat tolerance and are sensitive to disturbance. Overall, the Study Area is of high ecological value.
8.12.2 The species of conservation interest recorded along the alignment were also observed in other locations in the broader survey area (Figures 8.14 to 8.19). The species of conservation interest would, therefore, appear to be widely distributed in the wider survey area and do not appear confined to any single location. It is interesting to note that the majority of species of conservation concern were also recorded along the existing Tung Chung Road (15 faunal species of conservation interest recorded) indicating that the conservation requirements of these species are being met and the operation of the existing road have not seriously compromised the species present.
8.12.3 Construction of the proposed road should, accordingly, be conducted in an appropriately ecologically sensitive manner, with particular attention given to avoidance or minimisation of disturbance through appropriate works scheduling and responsible works area maintenance. Many streams in the Study Area are of particularly high ecological value due to a previous low level of anthropogenic disturbance, and it is crucial that impacts to these highly sensitive habitats are avoided or minimised wherever possible. Loss of ecologically valuable habitat should be mitigated both on-site and off-site to the fullest possible extent.
8.12.4 Based upon this, in addition to the measures integrated into the design of the road such as reduction of the road footprint as far as possible to minimise habitat loss and a comprehensive drainage system to avoid and minimise impacts on the stream courses, a series of ecological mitigation measures have been proposed to reduce impacts to acceptable levels.
8.12.5 The effectiveness of impact mitigation measures will need to be assessed by the proposed environmental monitoring and audit programme. As discussed above, some residual impacts will occur but these are considered to be acceptable within the overall benefits of the scheme.
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