5. ecological impact assessment 5.1 introduction 5 · 2016-11-17 · outline zoning plan as coastal...

Outlying Islands Sewerage Stage 2 –

South Lantau Sewerage Works

5-1 B&V / ERM

5. ECOLOGICAL IMPACT ASSESSMENT

5.1 Introduction

This Section presents the findings of an assessment of the potential ecological impacts

associated with the construction and operation of the proposed Project in South Lantau. It

summarises the baseline information gathered from a literature review and baseline

ecological surveys on the terrestrial and marine ecological resources in South Lantau, and

describes the ecological importance of this area.

5.2 Legislation Requirement & Assessment Criteria

5.2.1 Technical Memorandum

The criteria for evaluating ecological impacts are laid out in the EIAO-TM. Annex 16 of

the EIAO-TM sets out the general approach and methodology for the assessment of impacts

to ecological resources arising from a project or proposal. Annex 8 of the EIAO-TM

recommends the criteria that can be used for evaluating such impacts.

5.2.2 Other Legislation

Legislative requirements and evaluation criteria relevant to this Study for the protection of

species and habitats of ecological importance include:

Country Parks Ordinance (Cap 208);

Forests and Countryside Ordinance (Cap 96);

Marine Parks Ordinance (Cap 476);

Wild Animals Protection Ordinance (Cap 170);

Protection of Endangered Species of Animals and Plants Ordinance (Cap 586);

Town Planning Ordinance (Cap 131);

Hong Kong Planning Standards and Guidelines Chapter 10 (HKPSG);

EIAO Guidance Note No. 6/2010, 7/2010, 10/2010 and 11/2010

United Nations Convention on Biodiversity (1992);

IUCN Red List of Threatened Species;

Convention on Wetlands of International Importance Especially as Waterfowl

Habitat (the Ramsar Convention); and

PRC Regulations and Guidelines.



5-2 B&V / ERM

5.3 Baseline Condition

This section details the baseline conditions of both terrestrial and marine ecological

resources of the habitats at South Lantau.

5.3.1 Terrestrial Ecology

In accordance with the requirements given in Clause 3.4.2.2 of the EIA Study Brief, the

Study Area for terrestrial ecology is defined by a distance of 500 m from the Project

Boundary (Figure 5.1). The Study Area covers a total area of approximately 1,215 ha in

southern Lantau Island including Lantau South Country Park and the areas zoned under the

Outline Zoning Plan as Coastal Protection Area and Green Belt.

Baseline conditions for each ecological component of the terrestrial environment of the

Study Area were evaluated based on information from the literature and focused field

studies conducted for the purposes of this EIA. Findings of the literature review and

baseline field surveys of the Study Area are summarised in the following sections.

5.3.2 Literature Review

A review of literature and recent aerial photographs was conducted to determine the

existing terrestrial ecological conditions within the Study Area, identify habitat resources

and species of potential conservation importance, and identify potential information gaps

in the baseline conditions of the habitats. The literature reviewed includes:

Porcupine! (1)

;

Hong Kong Biodiversity (2)

;

Revised Concept Plan for Lantau (3)

;

Field guides for terrestrial wildlife of Hong Kong (4)

;

EIA Report for Integrated Waste Management Facilities Phase 1 (5)

;

EIA Report for Liquefied Natural Gas (LNG) Receiving Terminal and Associated

Facilities (6)

;

EIA Report for Drainage Improvements in Southern Lantau (7)

;

EIA Report for Improvement to Tung Chung Road Between Lung Tseng Tau and

Cheung Sha (8)

;

(1) Newsletter of Department of Ecology & Biodiversity, The University of Hong Kong. Issues 1 to 33

(2) AFCD Biodiversity Newsletters. Available at: https://www.afcd.gov.hk/english/publications/publications_con/pub_con_hkbio.html

(3) Lantau Development Task Force (2005) Revised Concept Plan for Lantau

(4) Relevant field guides for terrestrial wildlife of Hong Kong available at:

https://www.afcd.gov.hk/english/conservation/hkbiodiversity/leaflets/leaflets_oth.html

(5) AECOM (2011) Integrated Waste Management Facilities Phase 1 – Feasibility Study: EIA Report Register No. AEIAR-123/2012

(6) ERM (2006) Liquefied Natural Gas (LNG) Receiving Terminal and Associated Facilities: EIA Report. EIA Register No. AEIAR-106/2007

(7) Maunsell (2005) Drainage Improvements in Southern Lantau: EIA Report. EIA Register No. AEIAR-093/2005

(8) Mouchel Asia Ltd (2002) Improvement to Tung Chung Road from Lung Tseng Tau to Cheung Sha: EIA Report. EIA Register No. AEIAR-

061/2002

../Figures/5.1.pdf

https://www.afcd.gov.hk/english/publications/publications_con/pub_con_hkbio.html

https://www.afcd.gov.hk/english/conservation/hkbiodiversity/leaflets/leaflets_oth.html



5-3 B&V / ERM

EIA Report for 132 kV Supply Circuit from Pui O via Chi Ma Wan Peninsula via

Sea Crossing towards Cheung Chau (9)

; and

Project Profile for Telecommunication Installation at Lot 591SA in DD328, Tong

Fuk, South Lantau Coast and the Associated Cable Landing Work in Tong Fuk,

South Lantau for the North Asia Cable (NAC) Fibre Optic Submarine Cable

System (10)

.

Project Profile for Asia-America Gateway (AAG) Cable Network, South Lantau

Lantau South Country Park

Over 50% of the Study Area (approximately 597 ha) is located within the Lantau South

Country Park (CP) designated under the Country Parks Ordinance in 1978. The Park

comprises an extensive area inhabiting many flora and wildlife such as, snakes, birds,

freshwater fish and protected plant species. Species of ecological interest include Hong

Kong Magnolia, orchids, Ferret Badger, Chinese Muntjac, Wild Boar and Romer’s Tree

Frog (11) (12) (13)

.

Green Belt

About 25% of the Study Area (approximately 295 ha) is located within the Green Belt (GB)

designated in the Outline Zoning Plan (OZP). The planning intention of GB is primarily to

define the limits of development areas, to preserve existing well-wooded hillslopes and

other natural features, as well as to provide passive recreational outlets for the local

population and visitors. GB mainly covers the extensive well-vegetated uplands and

hillsides, spurs and stream valleys, coastal pockets of land and isolated knolls adjoining the

Lantau South Country Park.

Coastal Protection Area

A long strip of land (approximately 162 ha) along the South Lantau Coast is zoned as

“Coastal Protection Area” (CPA) which covers backshore coastal habitats and the sandy

shore of the gazetted bathing beaches at Pui O, Cheung Sha and Tong Fuk. The purpose of

CPA is to protect the landscape and ecological value of these areas and/or to serve as a

buffer against encroachment of urban development into Country Parks, Special Areas and

Sites of Special Scientific Interest (SSSIs) (14)

.

Areas of Ecological Importance / Interest

Within the Study Area, a number of ecologically important / sensitive sites and habitats,

including Fung Shui woodlands in Tong Fuk and Shui Hau, the mangroves in Pui O and

(9) Mott Connell Limited (2001) 132 kV Supply Circuit from Pui O via Chi Ma Wan Peninsula via Sea Crossing towards Cheung Chau: EIA Report.

EIA Register No. AEIAR-051/2002

(10) ERM (2000) Telecommunication Installation at Lot 591SA in DD328, Tong Fuk, South Lantau Coast and the Associated Cable Landing Work in

Tong Fuk, South Lantau for the North Asia Cable (NAC) Fibre Optic Submarine Cable System: Project Profile. DIR-031/2000

(11) AFCD website. Lantau South Country Park.

http://www.afcd.gov.hk/english/country/cou_vis/cou_vis_cou/cou_vis_cou_ls/cou_vis_cou_ls.html

(12) Mouchel Asia Ltd (2002) Op Cit

(13) Mott Connell Limited (2001) Op Cit

(14) Planning Department (2001) Southwest New Territories Development Strategy Review. Final Report.

http://www.pland.gov.hk/pland_en/p_study/comp_s/swnt/final-report/final-report.htm

http://www.afcd.gov.hk/english/country/cou_vis/cou_vis_cou/cou_vis_cou_ls/cou_vis_cou_ls.html

http://www.pland.gov.hk/pland_en/p_study/comp_s/swnt/final-report/final-report.htm



5-4 B&V / ERM

horseshoe crab nursery ground in Shui Hau, are identified under the Revised Concept Plan

for Lantau, of which the mangroves in Pui O and horseshoe crab nursery ground in Shui

Hau fall within either the Lantau South CP or CPA.

In addition, to facilitate better planning for government construction projects and to

enhance protection on natural streams/rivers, Pui O and Tong Fuk streams are identified by

the AFCD as Ecologically Important Streams (EIS) with important ecological functions

such as providing habitats for diverse or rare animal or plant communities (15)

.

Terrestrial Habitats, Vegetation & Wildlife

Focused field surveys have been conducted at Chi Ma Wan (Ha Keng), Pui O Wan,

Cheung Sha and Shek Pik as part of the environmental impact assessments (EIA)

mentioned above (Figure 5.2). The most recent surveys completed were, however,

undertaken in April 2006 around Shek Pik and January 2010 around Cheung Sha, and no

recent field surveys have been conducted around the proposed project sites at Shui Hau,

Tong Fuk, San Shek Wan, Pui O and Ham Tin (Table 5.1).

Table 5.1 – Survey Periods for Previous Relevant Projects Project Major Survey Location Field Survey Period

Improvement to Tung Chung Road from Lung

Tseng Tau to Cheung Sha

Cheung Sha and Tung

Chung road

April 2001 – January 2002

132 kV Supply Circuit from Pui O via Chi

Ma Wan Peninsula via Sea Crossing towards

Cheung Chau

Pui O October 2000 – September 2001

Liquefied Natural Gas (LNG) Receiving

Terminal and Associated Facilities

Shek Pik February 2004 – April 2006

Drainage Improvements in Southern Lantau

Mui Wo July 2003 – March 2004

Integrated Waste Management Facilities Phase 1 Cheung Sha August - January 2010

Table 5.2 presents the major terrestrial habitats and associated wildlife identified within the

Study Area based on the above previous field surveys.

Table 5.2 – Major Terrestrial Habitats Identified within the Study Area (Information Based

on Literature Review) Habitat Description

Fung Shui

Woodland

Found at isolated locations near Shui Hau and Tong Fuk. Fung Shui Woodland are relatively old

growth with a height ranging from 6 m to 15 m and have not been disturbed for 20 to 50 years, and

are considered to be of high ecological value (1) (6)

Secondary

Woodland

Small area of secondary woodland located at Ngau Kwu Wan and Wang Tong.

Mainly located at the east of Pui O Wan, and around San Shek Wan and Cheung Sha.

Ecological value is generally expected to be moderate to high (1).

Two plant species of conservation importance were recorded in this habitat type near Pui O,

including Uvaria calamistrata and Malaisia scandens

Six plant species of conservation importance were previously recorded in Pui O in other EIA

study (1) including five rare to very rare species, Ailanthus fordii, Malaisia scandens, Uncaria

hirsuta, Uvaria calamistrata, and Xenostegia tridentata and one locally common but protected

species in China and Guangdong (Aquilaria sinensis).

(15) Environment, Transport and Works Bureau Technical Circular (Works) No. 5/2005 - Protection of natural streams/rivers from adverse impacts arising

from construction works

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5-5 B&V / ERM

Habitat Description

Mixed Shrubland Mainly located on the Chi Ma Wan Peninsula.

Shrubland is the dominant habitat and mainly located at Tong Fuk and Shui Hau as a continuous

area.

Ecological value is generally expected to be low to moderate (1).

Four species of conservation importance identified around Pui O, including Artocarpus

hypargyreus (found at southeast Pui O Wan), Epiphyte Cleisostoma simondii (found at southeast

Pui O Wan), Pitcher Plant Nepenthes mirabilis (found at southeast Pui O Wan) and Common

Rat Snake Ptyas mucosus (found near Shap Long Kau Tsuen) (1). These are either protected in

HK or listed as PRC Class II protected species.

Two species of conservation importance have been identified around Chi Ma Wan. Black Kite

Milvus migrans (found flying over the shrubland at Tai Long Wan) and, Pitcher Plant Nepenthes

mirabilis (found near Ha Keng) (1). Both are protected in Hong Kong and Black Kite is listed as

PRC Class II protected species.

Plantation

(Cheung Sha &

West Pui O Wan)

Exotic plantation is found along the Lantau Trail and South Lantau Road.

Ecological value of this habitat is generally considered to be moderate to high (4).

Two species of conservation importance identified which is the endemic Romer’s Tree Frog

Liuixalus romeri (found near Cheung Sha) and the Hong Kong Newt Paramesotriton

hongkongensis (found near Pak Kung Au) (2), which are protected species in HK. The toads

Leptolalax pelodytoides and Megophrys brachykolos were also reported previously near Cheung

Sha.

Shrubland/

Grassland Mixture

Grassland is mainly located at Tong Fuk and Cheung Sha, uphill of the South Lantau Road.

One locally protected species, Aquilaria sinensis, recorded in shrubland of Cheung Sha

(5)

Urban/ Village

Area

Consists of residential villages, cultivated land, roads, paths, parks, and wasteland in Shui Hau,

Tong Fuk, Cheung Sha, San Shek Wan and Pui O Wan, and artificial slopes at Cheung Sha and

part of the Shek Pik Reservoir.

Ecological value of this habitat is generally considered to be low (4).

Streams Five major stream systems are found, including Shui Hau Stream, Tong Fuk Stream, Cheung

Sha Stream, San Shek Wan Stream and Pui O Stream. Tong Fuk and Pui O Streams are

identified as Ecological Important Streams by the AFCD.

One rare plant species, Ceratopteris thalictroides, identified near a seasonal streams in

Cheung Sha (5)

Other natural streams can be found near San Shek Wan and Cheung Sha. Five species of

conservation importance identified which is the endemic Romer’s Tree Frog Liuixalus romeri

(found near Cheung Sha), Short-legged Toad Xenophrys brachykolos (found near Cheung Sha),

Chinese Cobra Naja atra (found near Cheung Sha), Lesser Spiny Frog Paa exilispinosa and

the Hong Kong Newt Paramesotriton hongkongensis (found near Pak Kung Au) (3) (5),. The

toads Leptolalax pelodytoides and Megophrys brachykolos were also reported previously near

Cheung Sha.

Four fish species of conservation importance within stream habitat of Pui O Stream, including

Predaceous chub (listed as Vulnerable in China Red Data Book), Beijiang Thick-lipped Barb,

the Philippine Neon Goby and Black-headed Thick-lipped Goby (3)

Marsh Found mainly in the vicinity of villages at Pui O. This habitat was mostly originated by the

abandoned agriculture land and usually located near streams (1). This habitat was invaded with

grasses and weed plants.

Four plant species of conservation importance were recorded at Pui O Marsh, including the

water fern Azolla imbricata, Ceratopteris thalictroides, Marsilea quadrifolia and Salvinia

natans (1).

Notes:

(1) Mott Connell Limited (2001) Op cit

(2) Advisory Council on the Environment Committee Paper NCSC 9/06. Available at:

http://www.epd.gov.hk/epd/english/boards/advisory_council/files/ncsc-paper-06-09.pdf

(3) Mouchel Asia Ltd (2002) Op cit

(4) ERM (2006) Op cit

(5) AECOM (2011) Op cit

(6) AFCD (2005) Biodiversity News Letter Issue 8

Available at: https://www.afcd.gov.hk/tc_chI/publications/publications_con/files/hkbonewsletter8.pdf

https://www.afcd.gov.hk/tc_chI/publications/publications_con/files/hkbonewsletter8.pdf



5-6 B&V / ERM

The literature review indicates that Mixed Shrubland and Plantation are the dominant

habitat types within the Study Area. Whilst some vegetation and wildlife species of

conservation importance have been documented in the literature (16)

, only very limited

information on general terrestrial wildlife was available within the Study Area.

5.3.3 Baseline Terrestrial Ecological Survey

Findings of the literature review suggest that only limited up-to-date baseline information

on the terrestrial ecological characters of the Study Area is available. Terrestrial ecological

surveys were conducted to provide up-to-date baseline information for establishing an

updated general ecological profile of the Study Area and describing the characteristics of

each habitat found.

The methodology of the ecological surveys makes reference to the technical guidelines of

ecological assessment in Annex 16 of EIAO-TM, and the related Guidance Notes (GN

7/2010 and GN 10/2010).

As per the requirements of the EIA Study Brief, the recommended terrestrial ecological

field surveys were undertaken with a duration of six months covering the wet season

(Table 5.3).

Table 5.3 – Baseline Survey Dates Ecological Survey 2010 2013 2014

(1) 2016

(2)

May Jun Jul Aug Sep Oct Nov July Sep Sep Jul Aug

Habitat Mapping and

Vegetation

Avifauna (Day)

Avifauna (Night)

Terrestrial Mammal (Day)

Terrestrial Mammal (Night)

Bat survey (Dusk)

Herpetofauna (Day)

Herpetofauna (Night)

Dragonflies & Butterflies

Aquatic fauna

Intertidal Fauna

Subtidal Fauna

Notes:

(1) Design changes n the sewerage scheme was made in year 2014, subsequently a site-specific ecological survey was carried

out during September 2014 to provide up-to-date ecological information of the project elements with design changes,

including Tong Fuk SPS, Cheung Sha SPS, San Shek Wan SPS (Proposed & Alternative Sites), San Shek Wan STW and

Pui O SPS.

(2) A verification survey was also conducted in 2016 to provide supplementary information on the existing condition of marine

ecological habitats and freshwater aquatic assemblages. Detailed survey findings of verification survey are presented in

Annex 5C.

The duration for the survey was well covered to ensure that the field data obtained are

representative. The terrestrial ecological surveys included:


../Annex/Annex%205C.pdf



5-7 B&V / ERM

Habitat and Vegetation Surveys; and

Wildlife Surveys (including terrestrial mammal, avifauna, herpetofauna, butterflies

and odonates and freshwater aquatic assemblages).

Figure 5.3 shows the terrestrial ecology sampling points and survey transects within the

Study Area. Methodology of the baseline ecological surveys is presented in Annex 5A.

Results of the terrestrial ecological surveys are summarized below.

Habitat & Vegetation Survey

Habitats recorded within the Study Area include Fung Shui woodland, mixed woodland,

plantation, shrubland-grassland, cultivated land, marsh, stream/channel,

urbanised/disturbed area and coastal habitats including mangrove, sandflat, rocky shore

and sandy shore which are discussed in detail under Marine Ecology (Figures 5.4 and 5.5).

Table 5.4 summarized the number of plant species recorded in, and total area occupied by

each habitat in the Study Area, and full list of recorded plant species is presented in Annex-

5B-1. A total of 376 plant species were recorded within the Study Area, 261 of which are

natives while 110 are exotics (Table A1 of Annex 5B-1). Most species recorded are

common species and six are restricted. Four plant species, Araucaria heterophylla, Dypsis

lutescens, Dimocarpus longan, and Gnetum luofuense, are categorized as near threatened

or vulnerable under IUCN Red List; however Araucaria heterophylla, Dypsis lutescens,

Dimocarpus longan are common species in cultivation horticulture, thus the recorded

individuals are considered to be cultivated by local villagers or for landscape purpose.

Gnetum luofuense is commonly found entangling large trees in woodlands and is

considered fairly common in Hong Kong. Two recorded species, Aquilaria sinensis and

Artocarpus hypargyreus, are common/ very common and three species (Aquilaria sinensis,

Pavetta hongkongensis, Artocarpus hypargyreus) protected under local or mainland

regulations were recorded (Figures 5.4a-m). Recorded in the marsh, Water Shamrock

Marsilea quadrifolia are considered very rare and Salvinia natans are considered rare in

Hong Kong. Although Lagerstroemia speciosa is protected under Cap. 96, it is widely

planted in Hong Kong’s countryside as ornamental trees and thus not considered as species

of conservation importance.

Within the Project Site, a total of 206 plant species were recorded; all of which are

common species, except for one protected species recorded at San Shek Wan STW and

San Shek Wan SPS Alternative Site (Table A2 of Annex 5B). The proposed sewers and

rising mains would mainly be laid under existing roads and paths which are void of

vegetation. Habitat descriptions of each proposed pumping station/sewage treatment

works are summarised in Table 5.5.

Table 5.4 – Plant Species Number Recorded within Each Habitat of the Study Area Habitat Number of Plant Species Total Area within the Study Area (ha)

Terrestrial

Mixed Woodland 146 305.5

Fung Shui Woodland 97 2.9

Plantation 110 163.9

Shrubland-grassland 94 609.4

Cultivated Land 48 5.8

Marsh 61 18.4

Stream/Channel 32 20.4

Urbanised/Disturbed Area 112 105.1

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../Annex/Annex%205A.pdf

../Figures/5.4a-m.pdf

../Figures/5.5.pdf

../Annex/Annex%205B.pdf







5-8 B&V / ERM

Habitat Number of Plant Species Total Area within the Study Area (ha)

Coastal

Mangrove 10 2.9

Rocky Shore 19 3.6

Sandy Shore 18 9.6

Sandflat - 24.0

Table 5.5 – Habitats Recorded within Each Sewage Pumping Station (SPS)/ Sewage

Treatment Works (STW)

SPS/STW Habitats

Proposed Site

Pui O Urbanised/ disturbed area, shrubland/grassland and plantation

San Shek Wan STW Urbanised/ disturbed area and mixed woodland

San Shek Wan Mixed Woodland

Cheung Sha Cultivated Land

Cheung Fu Street Plantation

Tong Fuk Shrubland-grassland,drainage,urbanised/ disturbed Area

Shui Hau Plantation

Alternative Site

San Shek Wan Mixed woodland

Mixed Woodland and Fung Shui Woodland

Mixed woodland was mainly found along stream ravines, at sheltered foothills and behind

sandy or rocky shores (Figure 5.4). The mixed woodlands were mostly young in nature

with a canopy height of 5-12m and dominated by a mixture of native pioneer species

including Schefflera heptaphylla, Sapium sebiferum, Claoxylon indicum, Zanthoxylum

avicennae, Alangium chinense and Celtis sinensis, backshore species including Hibiscus

tiliaceus and Pandanus tectorius and planted species including Acacia confusa and

Dimocarpus longan. The understorey was densely vegetated and dominated by a variety

of tree, shrub and herb species including Litsea glutinosa, Psychotria asiatica, Litsea

rotundifolia, and Liriope spicata.

The oldest woodlands were the Fung Shui woodlands located behind Shui Hau and Tong

Fuk. These woodlands were dominated by native tree species such as Aquilaria sinensis,

Schefflera heptaphylla, Ficus variegata, Cinnamomum camphora and Aporusa dioica.

Mature fruit trees including Dimocarpus longan, Litchi chinensis, and Clausena lansium

were not uncommon in these Fung Shui woodlands. Canopy species reached a height of 8-

14m and some trees of considerable sizes were found. The understorey was densely

vegetated and dominated by woody species including Litsea rotundifolia, Psychotria

asiatica, Ardisia quinquegona and seedlings of canopy species such as Schefflera

heptaphylla and Dimocarpus longan.

There were a total of 146 plant species recorded within the mixed woodland and 97 plant

species recorded within the Fung Shui woodland (Table A1 of Annex 5B). Two plant

species of conservation importance, Incense Tree Aquilaria sinensis and Hong Kong

Pavetta Pavetta hongkongensis were recorded.

Incense Tree is a common tree in Hong Kong but is listed in Protection of Endangered

Species of Animals and Plants Ordinance (Cap 586). It is also listed as a Category II

protected plant in China, in the List of Wild Plants under State Protection and is listed as

‘vulnerable’ by both the China Plant Red Data Book and by IUCN (2015). It is frequently

found in the Study Area and within the footprint of San Shek Wan SPS Alternative Site.





5-9 B&V / ERM

Hong Kong Pavetta is a common understory species found in woodland habitat in Hong

Kong, but it is protected under Forests and Countryside Ordinance Cap. 96.

Plantation

Plantation was located mainly along roadsides, near developed areas and above catchwater

(Figure 5.4). Most trees were exotic species, including Acacia confusa, Casuarina

equisetifolia and Pinus elliotii. A number of native tree, shrub and herb species had

colonized the understorey, but at a lower density and diversity than in the understory of the

mixed woodland. Understorey of some plantation patches were also cleared regularly as a

maintenance practice and therefore with few species established. Despite its tall canopy

and rapid growth, the plantation remained relatively simple in structure, was immature and

lacked diversity. A total of 110 species was recorded in plantation habitat, in which one

plant species of conservation importance, Silver-back Artocarpus Artocarpus hypargyreus,

was recorded. The locally common Silver-back Artocarpus is not listed under any local or

mainland legislation, but is classified as vulnerable in the IUCN Red Data List since 1998 (17)

. Silver-back Artocarpus is Near Threatened (NT) in China and is also recorded in

China Plant Red Data Book and Illustration of Rare and Endangered Plants in Guangdong

Province (18)

.

Shrubland-grassland

Shrubland-grassland dominated most of the exposed hillsides within the Study Area

(Figure 5.4). Vegetation cover of this habitat was fairly shrubby, some reaching a height

of 3-5 m, although in a few places it was formed by prolonged abandonment of cultivated

land or maintained by hill fires during the grave sweeping festivals, which interrupt the

natural succession of vegetation. Shrubland-grassland was dominated by a variety of tree

and shrub species including Sapium sebiferum, Aporusa dioica, Claoxylon indicum,

Rhodomyrtus tomentosa and the fern species Dicranopteris pedata. Exotic tree species

were also planted along some trails on Shrubland-grassland habitats to speed up succession.

In total 94 plant species were found during the surveys within Shrubland-grassland.

Cultivated Land

Patches of cultivated land were scattered near marshes, villages and on hillsides throughout

the Study Area (Figure 5.4). It was composed of tree nursery, orchard, and vegetable

fields. Most of the cultivated lands are semi-active or abandoned during the survey period.

A total of 48 plant species were recorded.

Marsh

Marshes were mostly recorded at the lowland area of Pui O and Shui Hau near the estuary

(Figure 5.4l). It was formed after abandonment of cultivated land and permanently fed by

brackish water. Some marshes were degraded due to development which disturbed or

encroached the marshes. Plant species recorded include remnants of crops such as

Colocasia esculenta, wetland dependent species including Cyclosorus interruptus,

Marsilea quadrifolia, Salvinia natans, pioneer native tree species including Sapium

sebiferum, Ficus hispida, grass species including Panicum repens, Paspalum paspaloides,

and backshore vegetation including Clerodendrum inerme and Excoecaria agallocha. A

(17) IUCN Red List (2014). Available from: http://www.iucnredlist.org/details/32383/0

(18) Hu QM, Wu TL, Xia NH, Xing FW, Lai CCP & Yip KL (2003) Rare and Precious Plants of Hong Kong. AFCD.










http://www.iucnredlist.org/details/32383/0



5-10 B&V / ERM

total of 61 plant species were recorded. Among these, Water Shamrock Marsilea

quadrifolia are considered very rare and Salvinia natans are considered rare in Hong Kong

(Xing et al. 2000).

Stream/Channel

Five major streams, referred to as Pui O Stream, San Shek Wan Stream, Cheung Sha

Stream, Tong Fuk Stream and Shui Hau Stream, were recorded within the Study Area

(Figure 5.4). Two streams, Pui O Stream and Tong Fuk Stream, were considered as

Ecologically Important Stream (EIS). The flows at the upper courses of these streams are

intercepted by the catchwater (which is labelled as “channel” due to its concrete nature).

The middle courses are fairly natural and embraced mainly by mixed woodland and

shrubland-grassland. The lower courses are subject to different levels of modification as

they pass under roads and through villages and cultivated land before reaching the sea. A

total of 32 plant species were recorded, including riparian species (e.g. Cleistocalyx

nervosum, Sterculia lanceolata) and typical vegetation found in other habitats which lie

along the streams (e.g. mangrove species at the estuary and woodland species at the ravine).

Urbanised/Disturbed Area

Road, villages, residential areas, recreational facilities, prison and other built-up area

mainly constitute urbanised/disturbed habitats. Species recorded are mainly exotic species

planted for landscaping purposes. A total of 112 plant species were recorded.

Habitats in Coastal Area

Habitats in coastal area include mangrove, sandflat, rocky shore and sandy shore. Their

locations within the Study Area are shown on Figure 5.4 and detailed description of the

coastal habitats is provided in Section 5.3.2 ‘Habitats in Coastal Area’.

Wildlife Survey

Avifauna

A total of 44 species of birds were recorded within the Study Area (Table B1 of Annex 5B).

Most are common in Hong Kong.

Bird abundance and species richness were low in stream/channel, shrubland/grassland and

cultivated land and Fung Shui woodland, low to moderate in marsh, mixed woodland,

plantation and urbanised/ disturbed area.

Five species were considered of conservation importance. These included Reef Egret

Egretta sacra, Black Kite Milvus migrans, Collared Scops Owl Otus lettia, Greater Coucal

Centropus sinensis and Hwamei Garrulax canorus. All except Hwamei are Class 2

Protected Animal of PRC. Black Kite, Collared Scops Owl and Hwamei are listed in

Appendix 2 of CITES.

Reef Egrets were recorded from sandy/ rocky shore within the Study Area. This species is

common and widespread in Hong Kong and mainly occurs in rocky shores (Viney et al.

2005).

Black Kites were soaring above mixed woodland, shrubland/grassland within the Study

Area. This is a common resident in Hong Kong and occurs in many types of habitats.










5-11 B&V / ERM

Collared Scops Owls were recorded from plantations within the Study Area. This species

is a common resident in Hong Kong and widely found in woodlands.

Greater Coucal was recorded from plantation, urbanised/disturbed, shrubland/grassland

within the Study Area. This is a common resident in Hong Kong and occurs in many types

of habitats.

Hwamei were recorded from shrubland/grassland within the Study Area. This species is a

common resident in Hong Kong and mainly found in hillsides covered by thick shrublands.

Terrestrial Mammals

A total of eight species of mammals were recorded within the Study Area (Table C1 of

Annex 5B)). All are common in Hong Kong. Japanese Pipistrelle Pipistrellus abramus is

considered of conservation importance.

Japanese Pipistrelle was recorded from urbanised/disturbed area, mixed woodland,

cultivated land and plantation. This species is protected under Cap. 170 Wild Animals

Protection Ordinance (WAPO). Japanese Pipistrelle is the commonest bat species of

Hong Kong. This species forages in many types of habitats, including urban areas.

Herpetofauna

A total of seven species of amphibians were recorded within the Study Area (Table C1 of

Annex 5B). All are common in Hong Kong. Romer’s Tree Frog Liuixalus romeri, which

was previously found in a plantation area near Cheung Sha (2)

, was not recorded during the

baseline surveys and it was not found within the Project Site.

Chinese Bullfrog Hoplobatrachus chinensis (Figure 5.6) is considered to be of

conservation importance. This species is Class 2 Protected Animal of PRC. Chinese

Bullfrog was recorded from Pui O Marsh. The observed individuals were mostly froglets.

This species is fairly common in Hong Kong and mainly inhabits cultivated lands, ponds,

rivers and marshes.

A total of nine species of reptiles were recorded within the Study Area. All are common in

Hong Kong.

Copperhead Racer Elaphe radiata (Figure 5.6) is considered to be of conservation

importance. This species is classified as “endangered” by China Red Data Book.

Copperhead Racer was recorded from mixed woodland, plantation, shrubland/grassland

within the Study Area. This species is common in Hong Kong and occurs in many types of

habitats, including woodland edge, grassland, shrubland.

Butterflies & Odonates

A total of 27 species of dragonfly were recorded within the Study Area (Table D1 of Annex

5B). All are common in Hong Kong. No recorded species was considered to be of

conservation importance.

Abundance and species richness of dragonfly were very low in shrubland/grassland,

stream/channel and urbanised/disturbed area, low in Fung Shui Woodland and cultivated

land, and low to moderate in plantation, mixed woodland, and marsh.



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5-12 B&V / ERM

A total of 40 species of butterfly were recorded within the Study Area (Table E1 of Annex

5B). Most are common in Hong Kong. Indian Fritillary Argyreus hyperbius and Blue

Pansy Junonia orithya are uncommon in Hong Kong. No recorded species was considered

to be of conservation importance.

Abundance and species richness of butterfly were low in cultivated land, marsh,

stream/channel and Fung Shui woodland, and low to moderate in shrubland/grassland,

mixed woodland, plantation and urbanised/disturbed.

Freshwater Aquatic Assemblages Survey

A total of 54 species of freshwater aquatic fauna were recorded within the Study Area,

including 43 species of fish, six species of crustaceans, three species of insects and two

species of snails (Table F of Annex 5B). Among them, one fish species was considered

“Endangered” by IUCN (Japanese eel Anguilla japonica), one species was considered

‘Vulnerable’ in China Red Data Book (Predaceous Chub Parazacco spilurus), one species

was considered rare in Hong Kong and was classified as “Near Threatened” by IUCN

(Eye-spotted puffer Takifugu ocellatus). Two species were considered uncommon in Hong

Kong and evaluated as “Lower Risk/Near Threatened” by IUCN (Sleepy goby

Psammogobius biocellatus and Indo-Pacific tropical sand goby Favonigobius reichei).

One species was considered uncommon and evaluated as “Least Concern” by IUCN (Small

snakehead Channa asiatica). Another two species of fish have been evaluated by IUCN

but not considered under threats (Mullet Mugil cephalus – Least Concern (LC), and Grass

puffer Takifugu niphobles – Data Deficient (DD)). For aquatic invertebrates, all are

common in Hong Kong, and no recorded invertebrate species was considered to be of


A verification survey was also conducted in 2016 to provide supplementary information on

the existing condition of freshwater aquatic assemblages. The freshwater aquatic

assemblages in 2016 reported similar results as the baseline survey conducted in 2010, of

which four species are of conservation importance. Spotty band goby Glossogobius

olivaceus (uncommon species in Hong Kong and classified in IUCN – Least Concern) and

sesarma crab Pseudosesarma patshuni (endemic species to Hong Kong) were the

additional species of conservation importance recorded in the verification survey. Detailed

findings of the verification survey are presented in Annex 5C.

Generally, the flow in these streams was not high even during wet season. The flows in

Pui O Stream and Shui Hau Stream were relatively higher than those in other streams. The

diversity and abundance of aquatic fauna were higher in Pui O Stream, Tong Fuk Stream

and Shui Hau Stream, lower in Cheung Sha Stream, and the lowest in San Shek Wan

Stream. This might be attributed to the lack of lowland estuarine section in San Shek Wan

Stream (its outlet is located at a boulder shore). Pui O Stream has all the five fish species

of conservation concern, and two fish species of conservation concern were recorded in

Tong Fuk Stream.

5.3.4 Marine Ecology

In accordance with the requirements in Clause 3.4.2.2 of the EIA Study Brief, the Study

Area for marine ecology lies within the Southern Water Control Zone (SWCZ) as

designated under the Water Pollution Control Ordinance (Cap 358). The Study Area

covers the entire southern coastline of the Lantau Island and includes the waters off

southern Lantau.







5-13 B&V / ERM

Whilst various marine habitats and species can be found within the broad Study Area, the

immediate vicinity of the marine footprint of the proposed project (i.e. the submarine

outfall extending from San Shek Wan) consists of natural sandy and rocky boulder shores

with relatively shallow water depths (< 5 m). Anthropogenic disturbance is expected to be

minimal at this area, while the further offshore areas experience a higher level of

disturbance through marine traffic and fishing activities.

Baseline conditions for each ecological component of the marine environment of the Study

Area were evaluated based on information from the literature and focused field studies

conducted for the purposes of this EIA. Findings of the literature review and baseline field

surveys of the Study Area is summarised in the following sections.

Literature Review

A literature and recent aerial photograph review were conducted to determine the existing

marine ecological conditions within the Study Area, identify habitat resources and species

of potential conservation importance, and identify potential information gaps in the

baseline conditions of the habitats. The literature reviewed includes:

Porcupine! (19)

;

Hong Kong Biodiversity (20)

;

Revised Concept Plan for Lantau (21)

;

Field guides and published academic literature for marine habitats and fauna of

Hong Kong;

Consultancy Study on Marine Benthic Communities in Hong Kong (Agreement

No. CE 69/2000) (22)

;

A Study of Soft Shore Habitats in Hong Kong for Conservation and Education

Purposes (23)

;

AFCD marine mammal monitoring report (24)

;

EIA Report for Liquefied Natural Gas (LNG) Receiving Terminal and

Associated Facilities (25)

;

EIA Report for Drainage Improvements in Southern Lantau (26)

;

(19) Newsletter of Department of Ecology & Biodiversity, The University of Hong Kong. Issues 1 to 33

(20) AFCD (2010 – 2015) Biodiversity Newsletters. Issues 1 to 23

(21) Lantau Development Task Force (2005) Revised Concept Plan for Lantau

(22) CityU Professional Services Limited (2002) Consultancy Study on Marine Benthic Communities in Hong Kong (Agreement No. CE 69/2000).

Prepared for the Agriculture, Fisheries and Conservation Department (AFCD)

(23) Shin PKS, Cheung SG (2005) A Study of Soft Shore Habitats in Hong Kong for Conservation and Education Purposes: Final Report 2005. ECF

Project 23/99

(24) Hong Kong Cetacean Research Project (2015) Monitoring of Marine Mammals in Hong Kong Waters – Data Collection (2014-2015). Available at

https://www.afcd.gov.hk/english/conservation/con_mar/con_mar_chi/con_mar_chi_chi/files/Final_Report_201415.pdf. Prepared for AFCD

(25) ERM (2006) Op cit

(26) Maunsell (2005) Op cit

https://www.afcd.gov.hk/english/conservation/con_mar/con_mar_chi/con_mar_chi_chi/files/Final_Report_201415.pdf



5-14 B&V / ERM

EIA Report for Improvement to Tung Chung Road Between Lung Tseng Tau

and Cheung Sha (27)

;

EIA Report for 132 kV Supply Circuit from Pui O via Chi Ma Wan Peninsula

via Sea Crossing towards Cheung Chau (28)

;

EIA Report for Engineering Investigation and Environmental Studies for

Integrated Waste Management Facilities Phase 1 – Feasibility Study (29)

;

Project Profile for Asia-America Gateway (AAG) Cable Network, South

Lantau (30)

; and

Project Profile for Telecommunication Installation at Lot 591SA in DD328,

Tong Fuk, South Lantau Coast and the Associated Cable Landing Work in Tong

Fuk, South Lantau for the North Asia Cable (NAC) Fibre Optic Submarine

Cable System (31)

.

Findings of the literature review of the Study Area is summarised in the following sections.

Areas of Ecological Importance / Interest

Within the Study Area, a number of ecologically important / sensitive sites and habitats,

including natural mudflats and mangroves in Shui Hau Wan and Pui O, and horseshoe crab

nursery ground in Shui Hau Wan, are identified under the Revised Concept Plan for Lantau.

These habitats fall within the CPA.

Proposed Shui Hau Wan SSSI

Shui Hau Wan is a large natural sand/ mudflat (>10 ha) in Hong Kong, and is identified as

an Extremely Important soft shore habitat for conservation and education purposes in Hong

Kong (32)

. It is also one of the confirmed nursery sites for horseshoe crabs in recent

years (33) (34)

, and based on the abundance of juveniles, Shui Hau Wan is identified as the

key nursery ground for Tachypleus tridentatus (35) (36)

. The horseshoe crab nursery ground

at Shui Hau Wan is also a proposed Site of Special Scientific Interest (SSSI).

Marine Mammals

Two resident marine mammals are found in Hong Kong: the Indo-Pacific humpback

dolphin (Sousa chinensis, locally called Chinese White Dolphin) and the finless porpoise



(29) AECOM (2011) Engineering Investigation and Environmental Studies for Integrated Waste Management Facilities Phase 1 – Feasibility Study.

EIA Report. EIA Registered No. 201/2011.

(30) Atkins & EGS (2007) Asia-America Gateway (AAG) Cable Network, South Lantau: Project Profile. DIR-160/2007

(31) ERM (2000) Op cit

(32) Shin PKS, Cheung SG (2005) Op cit

(33) Chiu HMC, Morton B (1999) The Biology, Distribution and Status of Horseshoe Crabs, Tachypleus tridentatus and Carcinoscorpius

rotundicauda (Arthropoda: Chelicerata) in Hong Kong: Recommendations for Conservation and Management. Final Report. The Swire Institute

of Marine Science, The University of Hong Kong

(34) Li HY (2008) The Conservation of Horseshoe Crabs in Hong Kong. MPhil Thesis. The City University of Hong Kong

(35) Li HY (2008) Op cit

(36) Carcinoscorpius rotundicauda has not been recorded in Shui Hau Wan (Li 2008)



5-15 B&V / ERM

(Neophocaena phocaenoides) ( 37 )

. Whilst the distribution of Indo-Pacific humpback

dolphins is limited to the western waters of Hong Kong, which are influenced by

freshwater input from the Pearl River (38) (39)

, finless porpoises are common in the waters of

southern and eastern Hong Kong (40)

. Both species have previously been sighted in the

Study Area.

Baseline condition of marine mammal distribution and abundance within the Study Area

has been determined primarily from a review of findings from recent AFCD long-term

marine mammal monitoring (41) (42) (43) (44) (45)

, supplemented by findings from previous

relevant EIAs (46) (47) (48)

. Locations of marine mammal sightings reported in these literature

resources are presented in Figure 5.7. The data presented are collected between 2000 and

2015.

The key finding of the literature review is that, in recent years, Chinese White Dolphins

were frequently sighted in to the west and south of Lantau Island where the west coast of

Lantau was identified as the most important dolphin habitat (49)

. Fewer dolphin sightings

were observed in Shek Pik, north of Siu A Chau and southeast of Tai A Chau (Figure 5.7).

During the 12-month survey period between 2014 and 2015, only three sightings were

recorded at Southeast Lantau with the lowest mean group size of 1.0. Southeast Lantau

waters (i.e. across Shui Hau Wan and the Chi Ma Wan Peninsula and near Shek Kwu

Chau), therefore, represent only marginal habitat for Chinese White Dolphins. On the

contrary, the usage at West and Southwest Lantau of Chinese White Dolphins were

increased in the AFCD long term monitoring during April 2014 to March 2015 (50)

. The

West Lantau and Southwest Lantau were still the frequent occurrence waters of Chinese

White Dolphins, particularly near Tai O Peninsula, Kai Kung Shan, Peaked Hill, around

Fan Lau and Kau Ling Chung.

Important porpoise habitats were located to the south of Tai A Chau, southwest of Shek

Kwu Chau, south of Cheung Chau, and the waters between Shek Kwu Chau and the Soko

Islands

Finless porpoises were frequently sighted in Southeast Lantau, particularly south of Tai A

Chau, and between Shek Kwu Chau and Soko Islands. Between 2014 and 2015, the

porpoise groups were mainly sighted at south of Tai A Chau, southwest of Shek Kwu Chau,

south of Cheung Chau, and the waters between Shek Kwu Chau and the Soko Islands as

(37) Jefferson TA, Hung SK (2007) An updated, annotated checklist of the marine mammals of Hong Kong. Mammalia 2007: 105–114

(38) Parsons ECM (1998) The behaviour of Hong Kong’s resident cetaceans: the Indo-Pacific humpbacked dolphin and the finless porpoise. Aquatic

Mammals 24: 91–110

(39) Jefferson TA (2000) Population biology of the Indo-Pacific hump-backed dolphin in Hong Kong waters. Wildlife Monographs 144: 1-65

(40) Jefferson TA, Hung SK (2007) Op cit

(41) Chinese White Dolphin data from 2003-2008, finless porpoise data from 2004-2008. Hong Kong Cetacean Research Project (2009) Op cit

(42) Monitoring of marine mammals in Hong Kong water - Data collection (2009-10). Hong Kong Cetacean Research Project (2010).

(43) Monitoring of marine mammals in Hong Kong waters - Data collection (2010-11). Hong Kong Cetacean Project. (2011).

(44) Finless porpoise conservation. http://www.afcd.gov.hk/english/conservation/con_mar/con_mar_fin/con_mar_fin_fin/con_mar_fin_fin.html

(last visited on 3 Ocotber 2011). Agricultural, Fisheries and Conservation Department, Hong Kong.

(45) Hung SK (2015) Monitoring on Marine Mammals in Hong Kong Waters (2014 – 2015)

(46) ERM (2006) Op cit



(49) Hung SK (2015) Op cit


../Figures/5.7.pdf

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5-16 B&V / ERM

per the monitoring results between 2014 and 2015 (51)

(Figure 5.7). From survey between

2014 and 2015, the mean group size (2.7±2.57) was similar to the ones in previous

monitoring periods, but was slightly higher than the one in 2013 – 2014. Recent

monitoring results showed that inshore waters (i.e. Pui O Wan) is no longer utilized by

finless porpoises which was an area once known to be an important habitat for porpoises.

Specifically, the number of sightings and abundance of the two marine mammals in waters

near the proposed outfall location, i.e. off San Shek Wan around Cheung Sha and Pui O,

are low in comparison to other marine mammal habitats of Hong Kong. These waters are,

therefore, not considered to represent key habitats for both species, and the ecological

value of the waters within the immediate area of the proposed outfall is predicted to be low (52)

.

Intertidal & Subtidal Assemblages

Focused field surveys have been conducted at Shek Pik, Shui Hau Wan and Pui O Wan as

part of the EIA and projects mentioned above (Figure 5.8). The most recent surveys

completed were, however, undertaken in March 2006 around Shek Pik and January 2010

around Cheung Sha, and no recent field surveys have been conducted near the proposed

project site at San Shek Wan and Pui O (Table 5.6).

Table 5.6 – Survey Efforts for Previous Relevant Projects Project Major Survey

Location

Habitats Field Survey Period

Consultancy Study on Marine Benthic Communities in

Hong Kong

Off Lo Kei Wan,

Cheung Sha and Yi

Long Wan

Subtidal soft-bottom June – December 2001

(wet and dry seasons)

A Study of Soft Shore Habitats in Hong Kong for

Conservation and Education Purposes

Shui Hau Wan Intertidal soft-bottom June – December 2002

(wet and dry seasons)

Liquefied Natural Gas (LNG) Receiving Terminal and

Associated Facilities

Shek Pik Intertidal hard-and soft-

bottom

August 2005 and March

2006 (wet and dry

seasons)

Improvement to Tung Chung Road from Lung Tseng

Tau to Cheung Sha

Pui O Wan Intertidal hard- and

soft-bottom

March 2002

132 kV Supply Circuit from Pui O via Chi Ma Wan

Peninsula via Sea Crossing towards Cheung Chau

Pui O and Chi Ma Wan Intertidal hard- and

soft-bottom, subtidal

hard-bottom

October – December

2000

Engineering Investigation and Environmental Studies

for Integrated Waste Management Facilities Phase 1 –

Feasibility Study

Cheung Sha Intertidal hard- and


hard- and soft-bottom

August 2009 – January

2010

Telecommunication Installation at Lot 591SA in

DD328, Tong Fuk, South Lantau Coast and the

Associated Cable Landing Work in Tong Fuk, South

Lantau for the North Asia Cable (NAC) Fibre Optic

Submarine Cable System

Tong Fuk Intertidal hard- and


hard-bottom

February 2000

Asia-America Gateway (AAG) Cable Network, South

Lantau

Tong Fuk Subtidal hard-bottom September 2007

Table 5.7 present the major intertidal and subtidal habitats and associated assemblages

identified within the Study Area based on the above previous field surveys.



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5-17 B&V / ERM

Table 5.7 – Major Marine Habitats identified within the Study Area (Information based on

Literature Review) Habitat Description

Intertidal hard-

bottom

Expected to support assemblages typical of similar shores in Hong Kong.

Species associated with this habitat are usually common and widespread with no notable species of


Generally considered to be of low to moderate ecological value, dependent on size and naturalness.

Intertidal soft-

bottom

Natural intertidal mudflats and mangroves in Shui Hau Wan and Pui O, and horseshoe crab nursery ground in

Shui Hau Wan, are identified as habitats with high ecological and conservation value.

Bathing beaches at Tong Fuk, Cheung Sha and Pui O are generally devoid of assemblages due to

anthropogenic and natural disturbances and are thus considered as of low ecological value.

Other natural sandy/ boulder shores of south Lantau, e.g. at Shek Pik and Pui O Wan, are generally

considered to be of low ecological value (1) (2) (3)

Subtidal hard-

bottom

The SWCZ is influenced by the Pearl River Estuary and represents sub-optimal conditions for coral

recruitment and survival. It is thus anticipated that corals are much less abundant and diverse in this area

than in other parts of Hong Kong, and only scattered, isolated individuals/ colonies are expected to occur.

Previous surveys reported typical assemblages of sponges, bryozoan, mussels/ oysters, barnacles and urchins

at Chi Ma Wan (Tai Long Wan) (1), with a few isolated colonies of octocoral and ahermatypic corals

(gorgonian Euplexaura spp., soft coral Dendronephthya sp. and ahermatypic coral Tubastrea sp.) and small,

scattered and encrusting colonies of the hard corals Psammocora superficialis, Cyphastrea serailia, Porites

lobata, Goniopora stutchburyi and Oulastrea crispata recorded. One gorgonian species (5) and one hard coral

species (O. crispata) (6) were recorded in Tong Fuk previously.

Habitats in this part of Hong Kong are generally considered to be of low ecological value (1) (7).

Subtidal soft-

bottom

Generally dominated by small, short-lived polychaete and crustacean species which are common and

widespread benthos of Hong Kong seabed.

Species of conservation importance, e.g. amphioxus species, have not been reported in this part of Lantau.

Benthos assemblages off Cheung Sha was considered to be of low diversity and low ecological value (7)

Benthos assemblages off Lo Kei Wan, Cheung Sha and Yi Long Wan were considered to be of moderate to

high species diversity (4)

Generally considered to be of low to moderate ecological value, dependent on species diversity and rarity.

Notes:



(3) ERM (2006) Op cit

(4) CityU Professional Services Limited (2002) Op cit

(5) ERM (2000) Op cit

(6) Atkins & EGS (2007) Op cit


The literature review indicates that species of conservation importance are generally not

anticipated in the Study Area, with exceptions at the mangroves and intertidal mudflats at

Shui Hau Wan and Pui O which are regarded as habitats with high ecological and

conservation value. Intertidal and subtidal assemblages of the Study Area are expected to be

typical of similar habitats in this part of Hong Kong.

Baseline Marine Ecological Survey

Findings of the literature review suggest that some baseline information on the marine

ecological characters of the Study Area is available. Taking into account the marine footprint

of this Project (i.e. the submarine outfall extending from San Shek Wan) and the marine

ecological sensitive receivers along the South Lantau coastline (i.e. Subtidal Hard Bottom

Habitats with corals, Sandflat, Horseshoe Crabs), the marine baseline ecological surveys were

focused around intertidal and subtidal habitats off the South Lantau coast to provide up-to-

date baseline information for establishing an updated general ecological profile of the Study

Area and describing the characteristics of each habitat found.



5-18 B&V / ERM

The methodology of the ecological surveys makes reference to the technical guidelines of

ecological assessment in Annex 16 of EIAO-TM, and the related Guidance Notes (GN 7/2010

and GN 10/2010).

As per the requirements of the EIA Study Brief, the recommended marine ecological field

surveys were undertaken with a duration of six months covering the wet season (May to

November 2010) (Table 5.3). A verification survey was also conducted in 2016 to provide

supplementary information on the existing condition of marine ecological habitats. In general,

the survey findings in 2016 reported similar results as the baseline survey conducted in 2010.

Detailed survey findings of verification survey are presented in Annex 5C.

The duration for the survey was well covered to ensure that the field data obtained are

representative. The marine ecological surveys included:

Intertidal Survey;

Subtidal Coral Survey; and

Subtidal Benthos Survey.

Sufficient up-to-date baseline information on marine mammal of the Study Area is present in

the literature. Marine mammal baseline surveys are thus not considered necessary.

Figure 5.3 shows the marine survey transects and subtidal benthos survey points within the

Study Area. Methodology of the baseline ecological surveys is presented in Annex 5A.

Results of the marine ecological surveys are summarized below.

Habitats in Coastal Area

Habitats in coastal area include mangrove, sandflat, rocky shore and sandy shore. Their

locations within the Study Area are shown in Figures 5.4a-m and detailed description of the

coastal habitats is provided below.

Mangrove

Patches of mangrove were recorded at the estuary of Pui O Stream and Shui Hau Stream. A

total of 10 plant species were recorded in mangrove habitat including true mangrove species,

mangrove associates and backshore species, ie Avicennia marina, Aegiceras corniculatum,

Kandelia obovata, Zoysia sinica, Clerodendrum inerme and Pandanus tectorius. Among the

recorded species, Zoysia sinica is listed as a Category II protected plant in China and under

the List of Wild Plants under State Protection (Part 1). However, this species is considered

fairly common in Hong Kong.

Sandflat

Sandflat within the Study Area is located at the estuary of Shui Hau Stream which is a

proposed SSSI and considered to be a possible spawning and nursery ground for horseshoe

crabs. Three Horseshoe crabs juveniles (i.e. Tachypleus tridentatus) were recorded during

intertidal qualitative spot-checks. A total of 16 intertidal epifauna and infauna species were

recorded.

Sandy Shore


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5-19 B&V / ERM

Sandy shores within the Study Area include gazetted beaches at Cheung Sha and Tong Fuk.

Backshore species including Vitex rotundifolia, Ipomoea pes-caprae, Pandanus tectorius and

Hibiscus tiliaceus formed a narrow belt at the rear side of sandy shores. A total of 18 plant

species were recorded at the backshore vegetated areas.

Rocky shore

Rocky shores within the Study Area are generally present between the gazetted beached at

Tong Fuk, Cheung Sha and Pui O. Species recorded at rock shore are common and typical

fauna of this type of habitat along the coast, namely Mollusca, Arthopoda and Echinodermata.

Intertidal Survey

Intertidal surveys consisted of qualitative walk-through surveys and quantitative transect

surveys along four selected survey locations within the project site (Figure 5.3). A total of 41

intertidal fauna were recorded during intertidal surveys in the surveyed area, from both walk

through surveys and transect surveys (Table 5.8). The majority of the intertidal fauna was

species from Mollusca and Crustacea.

Qualitative walk-through surveys include the accessible shorelines along Shui Hau Wan, San

Shek Wan and Pui O Wan. Active search of horseshoe crabs were conducted in particular

from July to October during the active period of juveniles. Three Horseshoe crab juveniles

(i.e. Tachypleus tridentatus) were recorded in Shui Hau Wan Sandflat but not in other

surveyed area. Except Horseshoe crab juveniles, there was no other intertidal species of

conservation concern found.

Four intertidal habitats were located within the surveyed area. Locations I-1, I-2 and I-3 are

rocky shores / boulder shores, while Location I-4 is a sandflat. Results of line transect

surveys are summarized in Annex 5B.

Table 5.8 – Intertidal fauna recorded in the Study Area

Phylum/Class Species

Platyhelminthes Flatworm (Class Tubellaria)

Bivalvia Anomalocardia flexuosa

Barbatia virescens

Circe scripta

Meretrix meretrix

Saccostrea cucullata

Solen strictus

Tapes sp.

Gastropoda Batillaria sp.

Cellana sp.

Cerithidea sp.

Chlorostoma argyrostoma

Clithon sp.

Echinolittorina radiata

Echinolittorina trochoides

Lunella coronata

Monodonta labio

Nassarius festivus

Nerita sp.

Siphonaria sp.

Thais clavigera

Arthropoda Tachypleus tridnetatus

Crustacea Ligia exotica

Capitulum mitella

../Figures/5.3.pdf




5-20 B&V / ERM

Phylum/Class Species

Alpheus lobidens

Metapenaeus sp.

Petrolishthes japonicus

Hermit crab (Order Anomura)

Macrophthalmus sp.

Ocypode creatophthalmus

Scopimera sp.

Uca lactea

Uca arcuata

Gaetice depressus

Perisesarma bidens

Epixanthus frontalis

Philyra carinata

Scylla paramamosain

Mictyris sp.

Echinodermata Holothuria leucospilota

Choradata Gobies (Family Gobiidae)

A total of 18 intertidal faunal species were found in Locations I-1, I-2 and I-3. Species

composition of Locations I-1, I-2 and I-3 were almost the same except Gobies (Chordata) was

absent in Location I-3. 11 species from Mollusca (Cellana sp., Siphonaria sp., Monodonta

labio, Lunella coronata, Echinolittorina radiata, Echinolittorina malaccana, Thais clavigera,

Saccostrea cucullata, Barbatia virescens, Nerita sp., Chlorostoma argyrostoma), five species

from Arthropoda (Ligia exotica, Capitulum mitella, Petrolishthes japonicus, Epixanthus

frontalis, Gaetice depressus), and one species from Echinodermata (Holothuria leucospilota)

were found in the rocky / boulder shores. All of these species are common and typical fauna

of this type of habitat (Lai et al. 2006). No recorded species was considered to be of


A total of 16 species including both epifauna and infauna were found in Location I-4. 10

species from Mollusca (Anomalocardia flexuosa, Batillaria sp., Cerithidea sp., Circe scripta,

Clithon sp., Lunella coronata, Meretrix meretrix, Nassarius festivus, Nerita sp. and Tapes sp.),

five species from Arthropoda (Hermit crab, Macrophthalmus sp., Metapenaeus sp., Alpheus

lobidens and Scopimera sp.) and one from Annelida (i.e. flatworm) were found in the sandflat.

All of these species are common or typical fauna of this type of habitat (Fong et al. 2005). No

recorded species was considered to be of conservation importance.

In general, there were more benthos present in middle and lower intertidal shores in Locations

I-1, I-2 and I-3, but there were fewer benthos in lower intertidal shore for both epifauna and

infauna in Location I-4. Echinolittorina radiata and Saccostrea cucullata were the dominant

species in the rocky / boulder shores, while Batillaria sp. and Cerithidea sp. were the

dominant species in the sandflat. Zonations of benthos were also observed in the Study Area.

For example, the abundance of Cellana sp. increased from higher intertidal zone to lower

intertidal zone, while that of Echinolittorina malaccana decreased from higher to lower

intertidal zone in the rocky / boulder shores. On the other hand, abundance of Batillaria sp.

was the highest in the middle intertidal shore in the sandflat.

Shannon diversity index (H’) and evenness (J) within the Study Area are shown in Table 5.9.

Although the abundance of benthos was the highest in Location I-4, its H’ and J were lower

than Locations I-1, I-2 and I-3. The low H’ and J in Location I-4 were due to the dominant

species Batillaria sp. and Cerithidea sp. with a significantly higher abundance than other

species. On the other hand, evenness of benthos was higher in Locations I-1, I-2 and I-3,

hence the H’ was also higher. Zonation patterns were also observed in the intertidal shore.



5-21 B&V / ERM

There were higher H’ in the middle and lower intertidal shores than the higher shores in

Locations I-1, I-2 and I-3, while the H’ of lower intertidal shore was lower in Location I-4.

Horseshoe crab was not recorded during the quantitative transect surveys, but three horseshoe

crab juveniles (Tachypleus tridentatus) were found on the sandflat of Location I-4 during the

qualitative spot checks. During a recent horseshoe crab study (Shin et al. 2007), juveniles

were also recorded in Shui Hau. This suggested that the area is a possible spawning and

nursery ground for horseshoe crabs.

Subtidal Hard-Bottom Habitat

The Study Area is influenced by the Pearl River Estuary which represents sub-optimal

conditions for coral survival and recruitment. It is thus expected that the abundance and

diversity of corals in this area to be less than that in the eastern part of Hong Kong waters

where the water is more oceanic. Only small, isolated and scattered coral colonies which are

more tolerant to sedimentation are expected to occur within the Study Area. Subtidal coral

survey was conducted within the project site and details are presented below:

Subtidal Coral Survey

Dive surveys were performed on 18 and 30 September 2011 in locations near the proposed

outfall alignment and the nearby shorelines. A total of five sites were investigated (Figure

5.3).

Regarding the weather conditions, it was sunny with mild wind, and the underwater visibility

was very low (~ 0.5 m). The water depth in the survey area was shallow, most areas less than

mostly less than 3m, and the maximum depth less than 5m.

D-1, D-2 and D-3 were close to the outfall alignment and D-4 and D-5 were located in the

vicinity. D-1, D-4 and D-5 were natural coastlines while D-2 and D-3 were shallow coastal

waters.

Spot check dives revealed that the seabed at D-2 and D-3 was covered by sandy substrate only.

No subtidal fauna including corals was found in D-2 and D-3. There was no hard substrate in

these two transects available for corals or other epibenthos to colonise.

D-1, D-4 and D-5 were natural rock shores. Common sessile shallow subtidal fauna were

found on the natural rocks including the Rock oyster Saccostrea cucullata and the Green

mussel Perna viridis (Table 5.10). Very low coverage (< 1%) of hard coral Oulastera

crispata was recorded in these three transects, and the colonies of Oulastrea crispata were

small and scattered.

../Figures/5.3.pdf

../Figures/5.3.pdf



5-22 B&V / ERM

Table 5.9 – Shannon diversity index (H’) and evenness (J) of the intertidal benthos survey at different locations

Parameters Intertidal zone

Location I-1 Location I-2 Location I-3 Location I-4

September October September October September October September October

Abundance / m2 High 56 61 53 53 45 45 364 384

No. of species 3 3 3 3 2 2 4 4

H' 0.89 0.75 0.88 0.88 0.69 0.69 0.73 0.73

J 0.81 0.68 0.80 0.80 1.00 1.00 0.53 0.52

Abundance / m2 Middle 97 94 72 99 82 97 444 449

No. of species 11 12 11 11 11 12 8 12

H' 2.21 2.22 2.21 2.25 2.20 2.27 0.76 0.83

J 0.92 0.89 0.92 0.94 0.92 0.91 0.36 0.33

Abundance / m2 Lower 95 118 93 124 94 117 197 196

No. of species 15 12 12 12 12 11 4 5

H' 2.18 1.99 2.02 2.06 2.01 1.93 0.41 0.46

J 0.81 0.80 0.81 0.83 0.81 0.80 0.29 0.29

Abundance / m2 Overall 87 82 80 339

No. of species 18 18 17 16

H' 2.38 2.43 2.35 0.97

J 0.82 0.84 0.85 0.37



5-23 B&V / ERM

In accordance with the findings from spot dive, REA surveys were conducted at the three

transects with hard corals on the natural coastlines, i.e. D-1, D-4 and D-5. The REA transects

were parallel with the shore. The coastlines were mainly covered by large-sized boulders.

Table 5.10 – Subtidal fauna recorded during the Dive survey Common Name Species Commonness

Hard coral Oulastrea crispata Common

Rock oyster Saccostrea cucullata Very common

Green mussel Perna viridis Very common

The ecological attributes and substratum attributes of the REA transects were summarised in

Table 5.11. The areas were considered to be of low ecological value due to the low

percentage cover of a single species of common hard corals, and a lack of species of

conservation value.

Table 5.11 – Ecological Attributes and Substratum Attributes of the Transects Rank D-1 D-4 D-5

Ecological attributes

Hard coral 0.5 0.5 0.5

Octocoral (soft corals and gorgonians) 0 0 0

Black Corals 0 0 0

Dead standing corals 0 0 0

Substratum Attributes

Bedrock/continuous pavement 0 0 0

Boulder Blocks (diam.>50cm) 2 1 4

Boulder Blocks (diam.<50cm) 4 4 2

Rubble 1 2 1

Other 0 0 0

Soft Substrata

Sand 2 2 1

Mud/Silt 0 0 0

* Rank of percentage cover: 0 = None recorded; 0.5 = 1-5%; 1 = 6-10%; 2 = 11-30 %; 3 = 31-50%; 4= 51-75 %; 5

= 76-100%.

While only very low percentage cover of the common hard coral Oulastrea crispata was

found on the shorelines, dive survey confirmed that there was no coral on the majority of the

outfall alignment and the surrounding seabed. A very low percentage cover of hard corals

was found along the nearby natural coastlines, but these scattered coral colonies were a

common species in Hong Kong.

No other soft coral, gorgonian, or black coral was found during the survey. Other marine

lives in the area were of low diversity and were common species in Hong Kong.

Subtidal Soft-Bottom Habitat

Benthos assemblages within the Study Area are generally considered to be of low to moderate

ecological value. Small and short-lived polychaete and crustacean species which are common

and widespread benthos of Hong Kong seabed are the dominant benthic species within the

Study Area. Species of conservation importance, ie Amphioxus species, have not been

recorded in this part of Lantau. Subtidal benthos survey was conducted within the project site

and details are presented below:

Subtidal Benthos Survey



5-24 B&V / ERM

Abundance, number of species, Shannon diversity index (H’), evenness (J) and biomass of

benthos recorded from the four subtidal benthos sampling sites are shown in Table 5.12. A

total of 6,110 individuals from 70 species of benthic organisms were recorded at the four sites

(24 sampling stations, three replicates in each sampling station) within the Study Area (Annex

5B). There were 10 major taxa (Phylum) recorded in the benthic samples. Polychaeta was

the dominant Class across the study sites (over 13 Classes), with 36 species out of 70 in the

benthic samples. No rare species were recorded in the samples. The polychaete

Paraprionospio pinnata was the dominant species and comprised over 67% of the total

abundance. The total abundance was the highest at Location B-4 (total abundance was 2,100),

and its total number of species was also the highest among the four sites but with the lowest

biomass. On the other hand, total abundance was the lowest in Location B-1 (total abundance

was 1,034), which is the closest to the Pui O Wan, but its H’ and biomass were the highest

among the four sites. Species list and corresponding abundance are presented in Annex 5B –

Table L.

Table 5.12 – Abundance, number of species, Shannon diversity index (H’) and evenness (J) of

Benthos Recorded from Location A to D Location A Location B Location C Location D

Abundance 1,034 1,249 1,738 2,100

Number of species 44 50 41 52

H’ 2.51 1.68 1.09 1.41

J 0.66 0.43 0.29 0.36

Biomass (g) 129 38 63 35

The overall species diversity (H’) was moderate to high, and the mean value ranged from 1.09

to 2.51, in which the highest H’ was recorded at Location B-1 which is located nearest to the

Pui O Beach. The lowest H’ was recorded in Location B-3 which is located away from the

Pui O Beach, near Cheung Sha and with deep waters. For the Shannon diversity index (H’), a

value of < 1 indicates low diversity, 1-2 indicates moderate diversity and a value of > 2

indicates higher diversity.

The mean value of the evenness (J) recorded in the four sites ranged from 0.29 to 0.66. The

evenness index reflects how similar the abundance values for each species are within an

assemblage. For example, a value of 1 indicates that all species occur in equal abundance

whereas a value close to zero indicates that one species has very high abundance and the other

species are recorded at very low abundance. The indices indicated that there were limited

number of species of benthic organisms recorded across the sites and these were patchily

distributed.

Evaluation of Ecological Importance

The ecological importance of the habitats and wildlife identified within the Study Area are

evaluated in accordance with the EIAO-TM Annex 8 criteria, and presented in Table 5.13 to

5.24.






5-25 B&V / ERM

Table 5.13 – Evaluation of Mixed Woodland and Fung Shui Woodland Criteria Mixed Woodland Fung Shui Woodland

Naturalness Semi-natural dominated by native plants. Semi-natural composed of a mixture of mature exotic and

native plants. Size

Overall size of approximately 305.5 ha. Overall size of approximately 2.9 ha.

Diversity

Moderate diversity of plants (146 species) and

structural complexity, Low to moderate

diversity for bird, butterfly and dragonfly

Moderate diversity of plants (97 species) and structural

complexity.

Low to moderate diversity for bird and butterfly, low

diversity for dragonfly

Rarity

Plant species of conservation importance

included Incense Tree Aquilaria sinensis,

Gnetum luofuense and Hong Kong Pavetta

Pavetta hongkongensis.

Protected fauna species included Japanese

Pipistrelle, Black Kite and Copperhead Racer

Plant species of conservation importance included Incense

Tree Aquilaria sinensis.

No fauna of conservation importance

Re-creatability

It would take more than 20 years for the mixed

woodland to be re-created.

It would take more than 30-40 years for the fung shui

woods to be re-created.

Fragmentation Formed a belt along foothill and ravines. Fairly fragmented

Ecological Linkage Functionally linked to stream in close

proximity.

Functionally linked to mixed woodland in close

proximity.

Potential Value High, becoming mature woodland if given time

and protection from disturbance.

High, becoming mature woodland if given time and

protection from disturbance.

Nursery/ Breeding

Ground

No significant observation, but can provide

breeding habitats for mammals, birds, reptiles

and butterflies

No significant observation, but can provide breeding

habitats for mammals, birds, reptiles and butterflies

Age Moderate (around 20-30 years) based on tree

size, woodland structure and species

composition.

Mature (more than 50 years) based on tree size, woodland

structure and species composition.

Abundance/ Richness of

Wildlife

Low to moderate abundance for bird, butterfly

and dragonfly.

Low to moderate abundance for bird and butterfly, low

abundance for dragonfly.

Overall Ecological

Value

Moderate Moderate to High

Table 5.14 – Evaluation of Plantation Criteria Plantation

Naturalness Semi-natural, canopy dominated by exotic plants but undertorey of some patches colonised by

native species. Size Overall size of approximately 163.9 ha.

Diversity Moderate diversity of plants (110 species)

Low to moderate for bird and butterfly, very low for dragonfly

Rarity Plant species of conservation importance included Silver-back Artocarpus Artocarpus

hypargyreus.

Protected fauna species included Japanese Pipistrelle, Collared Scops Owl, Greater Coucal

and Copperhead Racer.

Re-creatability Habitat characteristics and species composition are easy to recreate. It will take about 10

years for the plantation to be re-created.

Fragmentation Not applicable.

Ecological Linkage Not functionally linked to any highly valued habitat in close proximity.

Potential Value Low to moderate, becoming mature woodland if given time and protection from disturbance.

Nursery/ Breeding Ground No significant observation, but can provide breeding habitats for birds and reptiles

Age Young (10 - 20 years) based on tree size, woodland structure and species composition.

Abundance/ Richness of Wildlife Low to moderate abundance for bird and butterfly, very low abundance for dragonfly.

Overall Ecological Value Low to moderate



5-26 B&V / ERM

Table 5.15 – Evaluation of Shrubland-grassland Criteria Shrubland-grassland

Naturalness Semi-natural habitats and disturbed by human activities such as fires.

Size Overall size of approximately 609.4 ha.

Diversity Moderate diversity of plants (94 species), low structural complexity. Low diversity for bird,

low to moderate for butterfly, very low diversity for dragonfly

Rarity None for plant species

Protected fauna species included Black Kite, Greater Coucal, Hwamei and Copperhead Racer

Re-creatability Habitat characteristics are easy to recreate but species composition may be different.



Potential Value Low to moderate, becoming mixed woodland if given time and protection from disturbance.

Nursery/ Breeding Ground No significant observation, but can provide breeding habitats for mammals, birds, reptiles and

butterflies

Age Not applicable.

Abundance/ Richness of Wildlife Low abundance for bird, low to moderate for butterfly, very low abundance for dragonfly

Overall Ecological Value Low to moderate

Table 5.16 – Evaluation of Cultivated Land Criteria Cultivated Land

Naturalness Man-made habitat mostly abandoned.

Size Small patches of active agricultural land were recorded within the Study Area with an overall

size of approximately 5.8 ha.

Diversity Low diversity of plants (48 species).

Low diversity for bird, butterfly and dragonfly

Rarity None for plant species.

Protected fauna species included Japanese Pipistrelle.

Re-creatability Habitat characteristics and species composition are easy to recreate.



Potential Value Low to moderate, some orchard and tree nursery may become mixed woodland if given time

and protection from disturbance.

Nursery/ Breeding Ground No significant observation, limited due to high level of human disturbance

Age N/A

Abundance/ Richness of Wildlife Low abundance for bird, butterfly and dragonfly

Overall Ecological Value Low

Table 5.17 – Evaluation of Marsh Criteria Marsh

Naturalness Semi-natural (cultivated land abandoned and subject to natural succession).

Size 18.4 ha

Diversity Low to moderate diversity of plants (61 species)

Low to moderate diversity for bird and dragonfly, low diversity for butterfly Rarity Plant species of conservation importance included Water Shamrock Marsilea quadrifolia and

Water Spangles Salvinia natans

Protected fauna species included Chinese Bullfrog

Re-creatability Moderate difficult to recreate due to hydrological conditions

Fragmentation Isolated stands but fairly intact

Ecological Linkage Hydrologically linked to streams.

Potential Value Moderate if protected from disturbance and conversion to other land use.

Nursery/ Breeding Ground No significant observation, but can provide breeding habitat for amphibian

Age N/A

Abundance/ Richness of Wildlife Low to moderate abundance for bird and dragonfly, low abundance for butterfly

Overall Ecological Value Moderate to high



5-27 B&V / ERM

Table 5.18 – Evaluation of Stream/Channel

Criteria Stream/Channel

Naturalness Semi-natural habitat, upper course intercepted by catchwater, middle course fairly natural and lower course

moderately modified Size Overall area approximately 20.4 ha, with its total length approximately 8.1 km.

Diversity High diversity of aquatic fauna

Low diversity of plants (32 plant species)

Low to moderate diversity for dragonfly, low diversity for bird and very low for butterfly

Rarity Common habitat type in Hong Kong.

One fish species was considered “Endangered” by IUCN (Japanese eel Anguilla japonica),

one fish species was considered Vulnerable in China Red Data Book (Predaceous Chub Parazacco spilurus),

three fish species were considered rare/ uncommon in Hong Kong and classified as “Lower Risk/Near

Threatened” by IUCN (Eye-spotted puffer Takifugu ocellatus, Sleepy goby Psammogobius biocellatus, and

Indo-pacific tropical sand goby Favonigobius reichei),

two uncommon species and classified as ‘Least Concern” by IUCN (Small snakehead Channa asiatica and

Spotty band goby Glossogobius olivaceus),

one endemic crustacean species (Sesarmind crab Pseudosesarma patshuni)

Re-creatability Habitat characteristics are difficult to recreate


Ecological Linkage Functionally linked to the intertidal habitats.

Potential Value Moderate if given time and protection from disturbance.

Nursery/ Breeding

Ground

Estuarine sections could act as nursery ground for marine/intertidal fauna. Also can provide breeding habitat

for dragonfly and amphibian

Age N/A

Abundance/ Richness

of Wildlife

Moderate for aquatic fauna; low to moderate abundance for dragonfly, low abundance for bird, and butterfly

Overall Ecological

Value

Moderate to high

Table 5.19 – Ecological Evaluation of Mangrove Criteria Mangrove

Naturalness Natural habitat

Size Approximately 2.9 ha

Diversity Very low diversity of plants (10 species).

Low to moderate diversity of bird, very low diversity for butterfly and no record of dragonfly

Rarity No terrestrial or intertidal flora or fauna of conservation importance found

Re-creatability Mangrove is moderately easy to recreate

Fragmentation Isolated small stands of mangroves

Ecological Linkage Linked to stream and subtidal habitats in close proximity.

Potential Value N/A

Nursery/ Breeding Ground No significant observation.

Age Not applicable.

Abundance/ Richness of Wildlife Low to moderate for bird, very low abundance for butterfly and dragonfly

Overall Ecological Value Moderate to high



5-28 B&V / ERM

Table 5.20 – Ecological Evaluation of Urbanised/ Disturbed Area Criteria Urbanised/ Disturbed Area

Naturalness Man-made habitat dominated by landscape plants and weed plants.

Size Major patches were recorded within the Study Area with an overall size of approximately 105.1 ha.

Diversity Moderate diversity of plants (112 species),

Low to moderate for bird and butterfly, very low diversity for dragonfly

Rarity No flora of conservation importance.

Protected fauna species included Japanese Pipistrelle and Greater Coucal

Re-creatability Habitat characteristics and species composition are easy to recreate.



Potential Value Low

Nursery/ Breeding Ground No significant observation. Limited due to high level of disturbance and low vegetation cover.

Age N/A

Abundance/ Richness of Wildlife Low to moderate for bird and butterfly, very low abundance for dragonfly

Overall Ecological Value Low

Table 5.21 – Evaluation of Rocky Shore and Sandy Shore

Criteria Rocky Shore Sandy Shore

Naturalness Natural habitat Largely natural, although some are modified due to

designation as public beaches Size Total area is approximately 3.6 ha. Total area is approximately 9.6 ha.

Diversity Low diversity for intertidal fauna (18 species) Low diversity for intertidal fauna (16 species)

Rarity No species of conservation importance were found No species of conservation importance were found

Re-creatability Habitat characteristics and species composition are

difficult to recreate.

Habitat characteristics and species composition are


Fragmentation N/A N/A

Ecological Linkage Not functionally linked to any highly valued habitat in

close proximity

Not functionally linked to any highly valued habitat

in close proximity.

Potential Value Low Low

Nursery/ Breeding

Ground

No significant observation No significant observation

Age N/A N/A

Abundance/ Richness

of Wildlife

Low abundance for intertidal fauna Low abundance for intertidal fauna

Overall Ecological

Value

Low to moderate Low

Table 5.22 – Ecological Evaluation of Sandflat Criteria Sandflat

Naturalness Natural habitat along intertidal zone

Size Total area of sandflat is approximately 24.0 ha

Diversity Low diversity for intertidal fauna (16 species)

Rarity Horseshoe crab juveniles were recorded during survey

Re-creatability Habitat characteristics and species composition on sandflat are difficult to recreate

Fragmentation Sandflat is fairly intact

Ecological Linkage Linked to stream and subtidal habitats in close proximity.

Potential Value Low

Nursery/ Breeding

Ground

Horseshoe crab breeding site

Age N/A

Abundance/ Richness

of Wildlife

Low to moderate abundance for intertidal fauna

Overall Ecological

Value

Moderate to high



5-29 B&V / ERM

Table 5.23 – Evaluation of Shallow Subtidal Hard Substrate Seabed and Subtidal Soft Substrate

Seabed Criteria Shallow Subtidal Hard Bottom Seabed Subtidal Soft Bottom Seabed

Naturalness Natural habitat Natural habitat

Size Total area within Study Area is approximately 72.4 ha Total area within Study Area is approximately 292.8 ha

Diversity Very low diversity of epibenthos and corals (1 species

of common hard coral Oulastrea crispata at very low

coverage)

Moderate to high diversity of benthic infauna (70

species)

Rarity No rare species was recorded No rare species was recorded

Re-creatability Habitat characteristics and species composition are


Habitat characteristics and species composition are


Fragmentation N/A N/A

Ecological Linkage Not functionally linked to any highly valued habitat in

close proximity

Not functionally linked to any highly valued habitat in

close proximity.

Potential Value Low Low

Nursery/ Breeding

Ground

No significant observation. No significant observation.

Age N/A N/A

Abundance/ Richness

of Wildlife

Low abundance for corals Relatively high abundance for benthic infauna

Overall Ecological

Value

Low Low to moderate

Table 5.24 – Evaluation of Coastal/Marine Waters Criteria Coastal/ Marine Waters

Naturalness Natural habitat and close proximity to the marine traffic lanes

Size N/A

Diversity The area is within the habitat range for both Chinese White Dolphin and Finless Porpoise

Rarity The South Lantau waters (extending from Fan Lau to south of Cheung Chau) is the only area in Hong Kong where

there is a major spatial overlap in the distribution of Indo-Pacific Humpback dolphin and Finless Porpoises.

Marked seasonal differences of these two species in terms of the use of South Lantau waters are observed.

Re-creatability N/A

Fragmentation N/A

Ecological Linkage Preferred marine mammal habitat occurs to the northwestern Lantau for Chinese White Dolphins and South

Lamma for finless porpoises

Potential Value South of Soko Islands has been considered as a potential marine park as included in the Proposed Southwest

Lantau Marine Park

Nursery/ Breeding

Ground

No key nursery areas

Age N/A

Abundance/

Richness of

Wildlife

Seasonal difference in dolphin distribution was observed in South and North Lantau waters. Abundance of

Chinese White Dolphins in South Lantau was low when compared to the preferred habitat in West and Northwest

Lantau. High concentrations of Finless Porpoise sightings can be found to the south of Tai A Chau and between

Shek Kwu Chau and Soko Islands.

Overall Ecological

Value

Low to Moderate



5-30 B&V / ERM

Table 5.25 – Evaluation of Floral and Faunal Species of Conservation Importance Recorded within the

Study Area Species Location and Activities (if

any)

Protection Status Distribution Commonness in

Hong Kong

Flora

Incense Tree

Aquilaria sinensis

In mixed woodland and

fung shui woodland. Found

in within the footprint of

San Shek Wan alternative

pumping station F(Option

2) and San Shek Wan

Sewage Treatment Works

Protected under the Protection of

Endangered Species of Animals and

Plants Ordinance (Cap 586). Category II

protected plant in the List of Wild Plants

under State Protection in PRC. Near

Threatened in PRC. Listed as

“Vulnerable” in the China Plant Red

Data Book and by IUCN (2009).

Lowland forests

and Fung shui

woodland

Common

Hong Kong

Pavetta

Pavetta

hongkongensis

In mixed woodland near Pui

O Village

Protected under Forestry and

Countryside Ordinance (Cap 96)

Fung shui

woodland and

lowland forest

Common

Silver-back

Artocarpus

Artocarpus

hypargyreus

In plantation along South

Lantau Road

Category II protected plant in the List of

Wild Plants under State Protection in

PRC. Near Threatened in PRC.

Fung shui

woodland and

lowland forest

Common

Water Shamrock

Marsilea

quadrifolia

In marsh - Ponds and ditches,

marshes

This species

listed as common

in the past but is

recently ranked as

very rare locally

due to loss of

paddy habitats.

Water Spangles

Salvinia natans

In marsh - Ponds, paddy

fields and ditches

This species

listed as very

common in the

past but is

recently ranked as

very rare locally

due to loss of

paddy habitats.

Zoysia sinica In mangrove, marsh and

sandflat, but outside of

Project Area

Category II protected plant in China and

under the List of Wild Plants under State

Protection (Part 1)

On sandy beaches,

river-bank

This species is

considered fairly

common in Hong

Kong

Luofushan Joint-

fir

Gnetum

luofuense

In woodland outside of

Project Area

Near threatened by IUCN Red list Commonly found

entangling large

trees

This species is

considered fairly

common in Hong

Kong

Fauna

Reef Egret

Egretta sacra

In sandy shore and rocky

shore

Protected under Cap. 170 – Wild

Animals Protection Ordinance;

Class 2 Protected Animal of PRC

Mainly found in

rocky shore

Uncommon

Black Kite

Milvus migrans

Soaring above mixed

woodland,

shrubland/grassland



Class 2 Protected Animal of PRC;

Appendix 2 of CITES

Occurs in many

types of habitats

Common

Collared Scops

Owl Otus lettia

In plantations Protected under Cap. 170 – Wild



Woodland Common

Greater Coucal

Centropus

sinensis

In plantation,

urbanised/disturbed,

shrubland/grassland



Class 2 Protected Animal of PRC;

Classified as “vulnerable” by China Red

Data Book

Occurs in many

types of habitats

Common



5-31 B&V / ERM

Species Location and Activities (if

any)


Hong Kong

Hwamei

Garrulax canorus

In shrubland/grassland Protected under Cap. 170 – Wild


Appendix 2 of CITES

Hillsides covered

by thick

shrublands

Common

Japanese

Pipistrelle

Pipistrellus

abramus

In urbanised/disturbed,

mixed woodland, cultivated

land and plantation


Animals Protection Ordinance

Occurs in many

types of habitats

Very Common

Chinese Bullfrog

Hoplobatrachus

chinensis

In marsh Class 2 Protected Animal of PRC Occurs in

cultivated lands,

ponds, rivers and

marshes

Fairly Common

Copperhead

Racer Elaphe

radiata

In mixed woodland,

plantation,

shrubland/grassland

Classified as “endangered” by China Red

Data Book

Occurs in many

types of habitats

Common

Predaceous Chub

Parazacco

spilurus

Pui O Stream

Tong Fuk Stream

“Vulnerable” in China Red List A widespread

species occurring

in most unpolluted

hill streams in

both upper and

lower courses.

Common

Sleepy goby

Psammogobius

biocellatus

Pui O Stream "Lower Risk/Near Threatened” by IUCN Streams in Sai

Kung and

northeastern New

Territories.

Uncommon

Indo-pacific

tropical sand

goby

Favonigobius

reichei

Pui O Stream

Tong Fuk Stream

Shui Hau Stream

"Lower Risk/Near Threatened” by IUCN Found in intertidal

waters throughout

Hong Kong.

Common

Japanese eel

Anguilla japonica

Pui O Stream

Shui Hau Stream

“Endangered” by IUCN Streams in Sai

Kung, Lantau

Island and Hong

Kong Island

Common

Eye-spotted

puffer

Takifugu

ocellatus

Pui O Stream

Shui Hau Stream

IUCN - Near Threatened Coastal areas and

large estuaries

Rare

Small snakehead

Channa asiatica

Pui O Stream “Least Concern” by IUCN Found in few

streams in North

district and on

Lantau Island. The

fish is also

cultivated in some

fish farms and are

available from fish

market.

Uncommon

Spotty band goby

Glossogobius

olivaceus

Pui O Stream “Least Concern” by IUCN Restricted

distribution in

Hong Kong, only

recorded in a few

reservoirs and

estuarines

Uncommon

Sesarmid crab

Pseudosesarma

patshuni

Shui Hau Stream - Found along river

banks of

mangroves

Endemic to Hong

Kong,

Uncommon

Hard coral

Oulastrea

crispata

San Shek Wan and to the

west of San Shek Wan

Cap 586 Shallow subtidal

hard substrate

seabed

Common



5-32 B&V / ERM

Species Location and Activities (if

any)


Hong Kong

Horseshoe crab

Tachypleus

tridentatus

Shui Hau Wan Sandflat - Intertidal sandflats Uncommon

Indo-Pacific

humpback

dolphin

Sousa chinensis,

Southeast Lantau near Shek

Kwu Chau

Cap. 170;

Cap. 586;

"Near Threatened" by IUCN;

Appendix 1 of (CITES);


Coastal / Marine

water

Restricted

Finless Porpoise

Neophocaena

phocaenoides

South of Tai A Chau, and

between Shek Kwu Chau

and Soko Islands, Pui O

Wan

Cap. 170;

Cap. 586;

"Vulnerable" by IUCN;

Appendix 1 of CITES;


Coastal / Marine

water

Restricted

5.4 Ecological Evaluation for the Project Site

The Project compromises the following elements:

A village sewerage system, which consists of gravity sewers and is connected to the trunk

sewerage system described below,

A trunk sewerage system, which consists of trunk sewers, sewage pumping stations

(SPSs) and twin rising mains along South Lantau Road for conveyance of sewage

collected from the village sewerage described above to the proposed sewage treatment

works described below. The proposed trunk sewerage system has six trunk sewage

pumping stations in Shui Hau, Tong Fuk, Cheung Fu Street, Cheung Sha, San Shek Wan

and Pui O areas.

A sewage treatment works (STW) located at San Shek Wan. The STW also involves its

associated submarine outfall for treatment and disposal of treated sewage.

Given the limited space required by the gravity sewers and rising mains and the fact that these

facilities will overlap with existing roads and alleyways, the main part of the Project Site lies

in areas where San Shek Wan STW and the six SPSs are located. Table 5.26 presents the

habitat composition of each proposed/ alternative SPS and STW, which also includes their

associated access roads leading to the existing South Lantau Road and Chi Ma Wan Road.

The proposed Shui Hau SPS, Cheung Fu Street SPS, as well as their associated access roads

are mainly located within plantation habitat. Trees were dominated by the species that are

commonly used for plantation purpose such as Acacia confusa, Bauhinia x blakeana,

Chrysalidocarpus lutescens and Archontophoenix alexandrae. The Tong Fuk SPS is located

on shrubland-grassland while its access road largely lies along urbanlised area. Plants

recorded within this SPS and its vicinity included shrubs Ricinus communis, herbs Ananas

comosus, Alocasia odora, grass Cynodon dactylon and some scattered trees such as Microcos

nervosa. The Cheung Sha SPS overlaps with a patch of cultivated land, on which fruit trees

such as Annona squamosa and Musa paradisiaca and common crops including Ipomoea

batatas were the dominant plant species. Both of the proposed and the alternative San Shek

Wan SPSs and their associated access roads fall within the habitat of mixed woodland that

were dominated by a mixture of native pioneer species including Mallotus paniculatus and

Microcos nervosa and planted species including Acacia confusa and Dimocarpus longan.

The Pui O SPS and its associated access road is largely located within shrubland/grassland

habitat, where the dominant plant species included Alocasia odora, Axonopus compressus,

Cyrtococcum patens, Desmodium triflorum, Hedyotis corymbosa, Senna occidentalis, Sida



5-33 B&V / ERM

rhombifolia. San Shek Wan STW and its associated access road are located within urbanized

area and mixed woodland habitat where Acacia confusa, Alangium chinense, Elephantopus

scaber, Liriope spicata, Lygodium japonicum, Paederia scandens were commonly found.

The plant species recorded within the Project Site during the baseline surveys are provided in

Table 5.25 and Table A2 of Annex 5B. Apart from Aquilaria sinensis, all the species are

common in Hong Kong, with no restricted, rare or protected species found within the direct

footprint of the STW and SPSs (Table 5.25).

In terms of wildlife, mammal such as Japanese Pipistrelle (Pipistrellus abramus), birds

including Chinese Bulbul (Pycnonotus sinensis), Oriental Magpie Robin (Copsychus saularis)

and Spotted Dove (Streptopelia chinensis) etc, reptile Chinese Gecko (Gekko chinensis),

butterflies including Angled Castor (Ariadne ariadne), Indian Cabbage White (Pieris canidia)

and Common Grass Yellow (Eurema hecabe) etc and dragonflies such as Red-faced

Skimmer (Orthetrum chrysis) and Common Blue Skimmer (Orthetrum glaucum) were

recorded within the Study Area during the baseline surveys (Tables B2, C2, D2 and E2 of

Annex 5B refer). All of the wildlife species recorded are common or very common in Hong

Kong, with no rare or protected species found. No species of conservation importance were

recorded within the direct footprint of the STW and SPSs (Table 5.25).

Based on the habitat composition as well as the vegetation and wildlife species recorded

within each SPSs and STW, the ecological values of habitats found at Shui Hau SPS, Tong

Fuk SPS, Cheung Sha SPS, Pui O SPS and San Shek Wan STW are considered to be low or

low to moderate, whilst part of the proposed and alternative San Shek Wan SPSs comprise

habitats with moderate ecological value (e.g. the mixed woodland are considered to have

moderate ecological values) (Table 5.26).

In terms of marine ecology, the Project site (where the submarine outfall diffuser will be

located) is of low ecological value due to its small size, low faunal diversity and absence of

key sensitivities from its inshore location.





5-34 B&V / ERM

Table 5.26 – Habitat Composition of Each Proposed/Alternative SPS and STW in hectares (ha) Habitat Ecological

Value of

Habitat

Within

Study Area

Shui Hau

SPS

Tong Fuk

SPS

Cheung Fu

Street SPS

Cheung Sha

SPS

San Shek

Wan SPS

(Proposed)

Pui O Trunk

SPS

San Shek

Wan STW

San Shek

Wan SPS

(Alternative)

Total

Habitat Loss

(1)*

Total

Habitat Loss

(2)*

Mixed Woodland Moderate 305.5 0 0 0 0 0.14 0 0.38 0.17 0.52 0.55

Plantation Low to

moderate

163.9 0.11 0 0.08 0 0 0 0.01 0 0.20 0.20

Shrubland-

grassland

Low to

moderate

609.4 0 0.04 0 0 0 0.15 0 0 0.19 0.19

Cultivated Land

Low 5.8 0 0 0 0.04 0 0 0 0 0.04 0.04

Urbanised/

Disturbed Area

Low 105.1 0 0.02 0 0 0 0.03 0.17 0 0.22 0.22

Total: 0.11 0.06 0.08 0.04 0.14 0.18 0.56 0.17 1.17 1.20

* ‘Total Habitat Loss (1)’ is calculated with the assumption that the Proposed San Shek Wan SPS will be adopted, while ‘Total Habitat Loss (2)’ is with the assumption that the Alternative San

Shek Wan SPS will be adopted



5-35 B&V / ERM

5.5 Potential Sources of Impact

Potential sources of impacts to ecological resources can arise from both the construction and

operation phases. Each is discussed in turn below.

5.5.1 Construction Phase

Land-based construction activities and minor marine dredging works of this Project have the

potential to affect ecological resources by:

Direct loss of habitats and vegetation removal within the footprints of the sewers, sewage

pumping stations and San Shek Wan STW;

Direct loss/ disturbances to benthic habitat within the marine works area;

Potential impact on recognized sites of conservation importance;

Habitat fragmentation and isolation, including restriction of wildlife utilisation of the area

(i.e. transit, feeding and roosting) especially for those inactive/ less mobile/ habitat-

specific wildlife nesting/inhabiting the habitats, and degradation of habitat quality/

ecological function;

Physical disturbance to the surrounding habitats and associated wildlife due to noise and

increased human activities (including construction vessels), etc.; and

Potential indirect impact on water quality, hydrodynamics properties, sedimentation rates

and pattern, as well as hydrology.

5.5.2 Operation Phase

The potential impacts of the operational phase of the Project on the ecology of the Study Area

are mainly due to perturbations to key water quality parameters due to discharge of treated

effluent from the STW and emergency overflow of untreated sewage from the trunk sewerage

and STW.

The operation of this Project would involve disinfection facilities within the STW but the use

of chemical disinfection which may be of concern to ecology (e.g. chlorine disinfection) is not

present.

Terrestrial ecological resources are not expected to be impacted by the Project’s operational

activities.



5-36 B&V / ERM

5.6 Impact Assessment


Habitat Loss

The major impact on terrestrial ecological resources will be direct habitat loss. While the

gravity sewers/rising mains will be installed underneath existing roads / accesses, the

proposed and alternative SPSs as well as San Shek Wan STW will be constructed in the

habitats including mixed woodland, plantation, shrubland-grassland, cultivated land and

urbanised/disturbed area. The habitat composition and their areas at each SPS and STW (i.e.

habitat loss) are summarized in Table 5.26, ecological values and the total areas of the

habitats within the Study Area are provided as well.

A total of 0.52 ha of mixed woodland, 0.20 ha of plantation, 0.19 ha of shrubland-grassland,

0.04 ha of cultivated land and 0.22 ha of urbanised/disturbed area would be lost due to site

formation works for the SPSs and the STW. If the alternative San Shek Wan SPS is adopted

instead of the proposed one, total habitat loss caused by this Project would be 0.55 ha of

mixed woodland, 0.20 ha of plantation, 0.19 ha of shrubland-grassland, 0.04 ha of cultivated

land and 0.22 ha of urbanised/disturbed area. Except for the proposed and alternative San

Shek Wan SPSs and STW, the habitats to be lost are of low or low to moderate ecological

values for all the other SPSs and STW. Approximately 0.52 – 0.55 ha of mixed woodland of

moderate ecological value will be lost due to the construction of the proposed/ alternative San

Shek Wan SPS, San Shek Wan STW and their associated access roads.

Site clearance will be undertaken prior to site formation works and all vegetation existing

within the affected habitats will be removed. According to the findings of the baseline

surveys, all the plants found within the Project Site are common species, with no flora species

of conservation importance recorded except at the San Shek Wan Alternative SPS location

and San Shek Wan STW where protected plant species Aquilaria sinensis in fair condition

were found in the footprint of the SPS (Table A1 of Annex 5B).

The mixed woodland to be lost will be compensated at suitable areas within the site boundary

of the San Shek Wan STW. For the plant species of conservation importance Aquilaria

sinensis found in the San Shek Wan SPS Alternative Site and San Shek Wan STW,

transplantation plan will be prepared prior to construction. The impact significance of habitat

loss arising from the construction is hence considered to be low to moderate, and impact of

vegetation removal associated with the Project construction would be low and managed to

acceptable level.

Impact on Recognized Sites of Conservation Importance

Within the Study Area, recognized sites of conservation importance include mangroves in Pui

O, Fung Shui woodlands in Tong Fuk and Shui Hau, Lantau South Country Park (CP)and

Ecologically Important Steams (EIS) at Tong Fuk and Pui O (Figure 5.1). The Project Site

does not encroach onto any mangroves, Fung Shui woodlands and Lantau South Country Park,

on which potential ecological impact is consequently not expected.

When the proposed pipe mains passes the EIS at Tong Fuk, pipe laying will adopt a bridge-

mounted type without disturbing the stream bottom and riparian vegetation along stream bank.

Also since there is sufficient headroom under the bridge, the pipe would be suspended above

the stream water. By using such construction method as well as the implementation of good

practice to control site run-off (see Section 4.9.1 for detailed mitigation measures to control


../Figures/5.1.pdf



5-37 B&V / ERM

construction site runoff and drainage), the potential impact of land based construction

activities on the ecology of the EISs is predicted to be minor.

For the proposed gravity sewer across the EIS at Pui O, the pipe will be laid by pipe-jacking

method in which a jacking pit and a receiving pit will be constructed on the land adjacent to

the stream and about 0.5 m diameter of pipe will be jacked from the jacking pit to the

receiving pit without disturbing the stream and riparian vegetation as the pits are located at

sufficient distance (at least 5 m) from the stream banks and the surrounding areas are free

from riparian vegetation. The pipe will be constructed underground below the Pui O EIS and

kept clear distance at least 2 m below the stream bed. The implementation of pipe laying

works by using pipe-jacking method will be scheduled to dry season. The construction and

operation of the pipe will not cause change in water level as the substratum above the tunnel

and the tunnel will be impervious to gravitational flows of stream water. As the scale of

works (i.e. the pipe is at 0.5 m in diameter and 5 m long) is small and there will be sufficient

distance below the stream bed, the vibration arisen from the pipe-jacking is minor. By using

such construction method as well as the implementation of good practice to control site run-

off (see Section 4.9.1 for detailed mitigation measures to control construction site runoff and

drainage), the potential impact on the water table and ecology of the EIS is predicted to be

minor.

Habitat Fragmentation and Isolation

The effect of habitat fragmentation and isolation arising from the Project is expected to be

minor. This is because firstly the large continuous and undisturbed habitats such as mixed

woodland and shrubland-grassland in the north of the Study Area will remain untouched

throughout the construction of the Project. Secondly most of the proposed sewers and rising

mains will be laid along existing roads / accesses. For the SPSs and STW whose footprints

extend to mixed woodland, plantation, shrubland-grassland or cultivated land, the affected

habitats are either in close proximity to disturbed area or are already fragmented in nature.

Hence, the reduction of wildlife utilisation of the areas (i.e. transit, feeding and roosting)

especially for those less mobile / habitat-specific species as a result of habitat fragmentation

would not be significant.

Noises, Human Activities and Other Disturbances

Secondary impacts to the surrounding habitats and associated wildlife may arise from the

potential of increased noise, human activities and other physical disturbances. Feeding or

breeding activities may be disturbed if noise levels are significant over a long term. The

impacts are expected to be low owing to the existing human presence in nearby areas, the

temporary nature and relatively small scale of the construction works. Given the

implementation of environmental mitigation measures and regular checks on construction

practices, the impacts are not expected to be unacceptable.

Impacts from Emergency Discharge during Operation Phase

Should the breakdown of pumping stations occur, raw sewage would be discharged into

adjacent streams when the emergency storage capacities are exceeded. However, the

possibility of emergency discharge of raw sewage is extremely low and it is expected to

happen for a very short period of time (i.e. 2 hours) because repair operations will be arranged

promptly. In addition, as the pumping stations are located at the lower section of these

streams and any discharges would flow downstream, it is expected that no impacts would

occur to the upstream regions of the streams and any potentially sensitive freshwater species

or ecosystems that may be present within those waters.



5-38 B&V / ERM

Based on the above, no unacceptable adverse impacts to stream/channel would be expected to

occur due to an emergency discharge from the breakdown of the pumping stations. It is also

important to note that although this event has been assessed for acceptability, the possibility

of its occurrence is extremely low because of sufficient preventive measures, including

standby pumps, dual power supplies and emergency storage, have been proposed for the

sewage pumping stations.


As indicated by the findings of the water quality impact assessment and water quality

modeling results (Section 4.8 refers), the predicted zone of influence of the Project is limited

to the immediate vicinity of the marine development footprint. In this context, the marine

ecological impact assessment in this section focuses on the area around the development

footprint.

Construction Phase

Potential impacts of the construction activities on marine ecological resources are presented in

Table 5.27.

Table 5.27 – Summary of Potential Construction Phase Impacts associated with Marine Dredging

Works for the Submarine Outfall Nature of Impact Marine Habitat Affected Potential Impact

Habitat Loss Subtidal Soft Bottom Habitat Loss/ Disturbance of approximately 0.13 ha of seabed

Changes in Water Quality

(i.e. Suspended Solids,

Dissolved Oxygen &

Contaminant Release)

Subtidal Soft Bottom Habitat Potential burial of benthic organisms

Subtidal Hard Bottom Habitat (including

corals)

Potential water quality impacts on isolated hard coral

colonies

Intertidal Habitats Potential water quality impacts on intertidal organisms

Coastal / Marine Water Habitat Potential water quality impacts on marine mammals

Vessel Disturbance Coastal / Marine Water Habitat Potential physical disturbance to marine mammals

Habitat Loss

The direct impacts of the minor marine dredging activities will be the loss of subtidal soft

bottom habitats and the potential removal of organisms associated with the installation of the

submarine outfall diffuser at the end of the submarine pipeline. The marine dredging area

would be very small, i.e. approximately 0.13 ha.

It is important to determine whether the area of disturbance contain species of interest or

noteworthy benthic assemblages, which will be lost during the marine works. Findings from

the literature reviews and the baseline subtidal benthos survey indicated that the benthic

assemblages within and in the vicinity of the working areas were dominated by polychaetes.

All species recorded are found to be common in Hong Kong and no rare species were

observed. As a result, the assemblages were regarded as low ecological value. No

unacceptable impacts are expected to be associated with the loss of subtidal soft bottom

habitat of low value.

Changes in Water Quality

Suspended Sediments

Subtidal Soft Bottom Habitat



5-39 B&V / ERM

The subtidal soft benthos in and around the proposed submarine outfall is considered to be of

low to moderate ecological value. Sessile organisms will be susceptible to the effects of

increased sediment loads through smothering and burial. Sediment may be deposited on the

seabed outside the reclamation sites during dredging and backfilling due to the dispersion of

sediments. Temporary impacts are expected to be the largest in the immediate vicinity of the

dredging works (i.e. in the mixing zone) when the works are underway, while impacts on the

wider marine environment (>1 km away from the works area) expected to be very low due to

gradual deposition of SS over a short distance.

Owing to the small scale and the low severity of sedimentation associated with the marine

dredging works (see Section 9.4.1.1 for details), the indirect disturbance on benthic

assemblages in the vicinity if the works area are expected to be of low severity and localized.

With the assumption that the temporarily affected subtidal soft bottom habitats due to marine

dredging works could be recolonised by fauna which is typical to that area, the temporary

disturbance to these low to moderate ecological value assemblages is not considered to be

unacceptable.

Subtidal Hard Bottom Habitat (including Corals)

Since no rare species was found in the subtidal hard bottom habitat in the vicinity of the

submarine outfall, shallow subtidal hard bottom habitat is regarded as low ecological value.

The transient nature of any increase in suspended sediment arising from marine dredging

works will have no unacceptable adverse impacts on this habitat of low ecological value.

Intertidal Habitats

Intertidal habitats within the Study Area which can be affected by the marine dredging works

include natural rocky shore, sandy shore and Shui Hau Wan Sandflat. Sediment dispersion

modeling results predicts that the SS elevations due to marine dredging will be transient and

will be confined to the proposed works area. Thus, it is expected that unacceptable impacts

from elevated SS levels to the intertidal assemblages, including the possible Horseshoe crab

breeding ground at Shui Hau Wan sandflat, within the Study Area will not occur.

Coastal / Marine Water Habitats

High suspended sediments do not have adverse impacts on marine mammals (i.e. Finless

Porpoises and Chinese White Dolphins) as they are well-adapted to hunt in turbid waters by

means of echolocation rather than merely depending on visual information. Moreover,

Finless Porpoises and Chinese White Dolphins are air-breathing, so elevated levels of

suspended sediments in waters would not cause any adverse effects on their respiratory

surfaces. However, the impact on these marine mammals may occur as an indirect result of

elevated SS levels. The minor marine dredging works may cause deterioration to water

quality, which may potentially impact the fisheries resources. Information from the fisheries

impact assessment (Section 6) indicates that indirect impacts are not predicted to impact

fisheries resources adversely as the elevation of suspended sediments due to sediment plume

will be transient and localized to the works area. Thus, impacts on marine mammals due to

reduced food supply are not predicted to occur. As a result, unacceptable impacts to marine

mammal habitats due to increased suspended sediment levels will not occur.

Dissolved Oxygen

The assessment examining potential impacts of elevated SS levels associated with the

proposed marine dredging works showed that the impacts are likely to be minor, localised to



5-40 B&V / ERM

the mixing zone and transient. Consequently, DO depletion as a result of dispersion of

sediment plumes associated with marine works of the Project is expected to be within

acceptable levels and its effect on marine ecological resources is also likely to be very limited.

Contaminant Release

Owing to the unpolluted nature of the seabed sediment within the dredging area (see Section 9

of this EIA Report), unacceptable water quality impacts due to the potential leaching of

metals and micro-organic pollutants from the disturbed sediments into the water column are

not expected to occur.

Vessel Operational Discharges

As discussed in Section 4.7.1, construction vessels have the potential for the liquid discharges

of uncontaminated deck drainage, potentially contaminated drainage from machinery spaces,

and sewage/grey water. These waste streams are all readily amenable to control as part of

appropriate practice on vessels. Possible impacts associated with construction vessel

discharges are therefore considered to be negligible.

Site Runoff from Land-based Construction Activities

Discharges and runoff from the land-based sites during the construction phase, particularly

during the site formation, excavation and backfilling works, will contain suspended solids

which could be a source of water pollution, causing short-term degradation of habitat quality.

However, considering that the scale of the construction works and with effective

implementation of good site management practices as well as mitigation measures mentioned

in Section 4.8, site run-off is not predicted to have an adverse impact on the natural coastline,

including Shui Hau Wan which is considered to be of moderate to high ecological value.

In summary, unacceptable impacts (elevated SS, nutrient and contaminant levels and DO

depletion) on sensitive receivers from sediment release associated with dredging works are

not expected to occur. Potential impacts arising from vessel operational discharges and land-

based site runoff during construction stage are also considered to be negligible.

Vessel Disturbance

Increased marine traffic during construction phase may result in physical disturbance to

marine mammals. In general, marine mammals have higher chance to be injured by high-

speed vessels, but the working vessels are not expected travelling in high speed. Underwater

noise from noisy equipment on working vessels may be a potential disturbance as marine

mammals are sensitive to sound and rely on sound to communicate and prey. The disturbance

from increased marine traffic may result in behavioral changes in marine mammals. Since the

duration of marine works is temporary in nature with a very low number of vessels to be

involved, and the marine works area is of very low usage of marine mammals, with the

implementation of marine traffic control, potential disturbances are expected to be minimized

and thus unacceptable impact during construction will be unlikely occurred.

Operation Phase

Impacts due to operational effluent discharge from the STW on marine ecological resources

are not expected as the discharge should satisfy the relevant requirements of WPCO-TM

effluent discharge standards (details refer to Sections 3 and 4). No unacceptable impacts are

thus anticipated.



5-41 B&V / ERM

To prevent sewage overflow from the sewage pumping stations due to plant failure, standby

pumps, dual power supply and emergency storage will be provided to the sewage pumping

stations. The standby pumps and dual power supply will maintain continuous operation of the

sewage pumping stations when the duty pumps or main power supply are down. In extreme

situation when both the duty and standby pumps are down or the dual power supply are failed,

the sewage entering the sewage pumping stations will be bypassed to the emergency storage

to prevent sewage overflow.

The SPSs and STW are all designed to have one standby unit (e.g. standby pumps and

standby treatment units) in case of equipment failure. Dual power supply will be in place in

case of power breakdown. In case of failure of dual power supply, emergency storage for

SPSs and STW would be in place to prevent emergency discharge. A 6-hour (ADWF)

emergency storage will be provided for each SPS. In addition to the sewage from their local

catchments, some sewage pumping stations (i.e. Tong Fuk SPS, Cheung Fu Street SPS and

San Shek Wan SPS) will also receive sewage from their upstream sewage pumping stations.

When one of these sewage pumping stations is down, sewage entering this sewage pumping

station from its local catchment will be bypassed to its emergency storage and all of its

upstream sewage pumping stations will stop operation and the sewage entering the upstream

sewage pumping stations from their local catchments will be bypassed to their emergency

storages. It will then provide the required minimum 6 hours of emergency storage to prevent

sewage overflow, which has accounted for the required time for travelling to and repairing of

all the sewage pumping stations as confirmed by DSD. Regular inspection and maintenance

will be carried out by DSD’s maintenance crew which will station in the San Shek Wan STW.

During non-office hours, existing mobile team from Ma Wan STW will be responsible to

back up the maintenance crew in San Shek Wan STW. With the implementation of above

preventive measures, the possibility of sewage overflow from the sewage pumping stations

will be extreme low. However, for safety purpose, a safety outlet will be provided to each

emergency storage to prevent flooding of the sewage pumping station.

The following precautionary measures will also be implemented to further minimize the

occurrence of the emergency discharges:

Regular maintenance and checking of plant equipment to prevent equipment failure;

Use standby pump in case of pump failure or maintenance required; and

Use dual power supply to keep the pump in operation in case of main power failure. A

contingency plan is recommended to be developed at the detailed design stage.

As discussed in Section 4, in the case of emergency discharge, untreated sewage would be

discharged into the lower course of nearby streams, including the ecological important

streams at Pui O and Tong Fuk, and this would change the water quality of the streams.

During the emergency discharge, the raw sewerage is supposed to directly drain into the

streams whilst such discharge will last for very short period. In addition, based on the

observation in the ecological surveys, the flows in the ecological important streams at Pui O

and Tong Fuk are relatively higher with the lower courses of the streams have subject to

different levels of modification. Given the relatively higher flow, the potential impact due to

untreated sewage discharge under emergency scenario would be temporary in nature and

quickly recovered. It is also important to note that discharge of untreated sewage in the event

of emergency is of very low likelihood given the control measures (e.g. standby units, dual

power supplies and emergency storages) will be in place.



5-42 B&V / ERM

With the emergency overflow of untreated sewage, it is predicted that the increase in E. coli,

Total Inorganic Nitrogen and Unionised Ammonia would cause a short-term deterioration of

the water quality conditions near the proposed outlet location, i.e. off San Shek Wan around

Cheung Sha and Pui O in case of the emergency discharge period. However, it is considered

that the water quality conditions would quickly recover once after the dilution effect with

seawater and after the termination of emergency discharge for both wet and dry seasons. If

the emergency discharge points are controlled at Pui O stream, soil and plants of nearby

habitats may be affected. According to the assessment result in Section 4.8.2, the emergency

discharge will not cause long-term or unacceptable impact on the nearby streams. The overall

ecological impact on adjacent habitats is considered to be temporary and minor after

implementation of preventive measures.

5.7 Impact Evaluation


Habitat Loss

From the information presented in Section 5.6.1, overall ecological impact associated with

habitat loss is considered to be low to moderate. An evaluation of habitat loss for each

affected habitat is provided in Table 5.28 – 5.32.

Mixed Woodland

Approximately 0.52 ha of mixed woodland will be lost due to the construction works of the

proposed site of San Shek Wan SPS. If the alternative site of San Shek Wan SPS is used, the

loss of mixed woodland will be slightly higher, which is 0.55 ha. In either option, the overall

unmitigated impact of habitat loss on mixed woodland is considered to be low to moderate

due to the small size of the affected area of moderate ecological value. For the protected plant

species Aquilaria sinensis recorded at San Shek Wan SPS (Alternative Option) and San Shek

Wan STW, transplantation plan will be developed accordingly (Figures 5.4j & 5.4l) (see

Table 5.28).

Table 5.28 – Impact of Habitat Loss on Mixed Woodland during Construction Phase Evaluation Criteria Mixed Woodland (Using the Proposed

San Shek Wan Trunk SPS)

Mixed Woodland (Using the Alternative

San Shek Wan Trunk SPS)

Habitat Quality The habitat quality is moderate.

Species of Conservation

importance

Plant species of conservation importance included Aquilaria sinensis at San

Shek Wan SPS Alternative Site and San Shek Wan STW (Refer to Table 5.12

for the flora and fauna species of conservation importance recorded within the

habitat of mixed woodland but outside the Project Site.)

Size/Abundance Permanent loss approximately 0.52

ha.

Permanent loss approximately 0.55 ha.

Duration The impact will persist during construction and operation phases.

Reversibility The loss is permanent and not reversible.

Magnitude The scale of the habitat loss and impact is small in the context of the

surrounding similar habitat, flora and fauna.

Overall Impact Before

Mitigation

Low to moderate Low to moderate

Plantation

Approximately 0.20 ha of plantation will be lost due to the construction works. The overall

unmitigated impact of habitat loss on plantation is considered to be low due to the small size




5-43 B&V / ERM

of the affected area, low to moderate ecological value and high recreatibility of the habitat,

and the fact that no flora and fauna species of conservation importance was recorded during

the surveys (see Table 5.29).

Table 5.29 – Impact of Habitat Loss on Plantation during Construction Phase Evaluation Criteria Plantation

Habitat Quality The habitat quality is low to moderate.


importance

No species of conservation importance was recorded within the affected area.

Hence no species of conservation importance is likely to be impacted. (Refer to

Table 5.13 for the flora and fauna species of conservation importance recorded

within the habitat of plantation but outside the Project Site. The affected areas

and species of conservation importance are illustrated in Figures 5.4a to 5.4m.)

Size/Abundance Loss of approximately 0.20 ha.


Reversibility Permanent loss is not reversible; temporarily affected area is reversible through

landscaping works within the SPS/STW




Mitigation

Low

Shrubland-grassland

Approximately 0.19 ha of shrubland-grassland will be lost due to the construction works.

Shrubland-grassland is a habitat of low to moderate ecological value and relatively high re-

creatability. No flora or fauna species of conservation importance was recorded within the

affected area. Also because of the small size of the area affected, the impact of habitat loss on

shrubland-grass is considered to be low (see Table 5.30).

Table 5.30 – Impact of Habitat Loss on Shrubland-grassland during Construction Phase Evaluation Criteria Shrubland-grassland

Habitat Quality The habitat quality is low to moderate.


importance


Hence no species of conservation importance is likely to be impacted. (Refer

to Table 5.14 for the flora and fauna species of conservation importance

recorded within the habitat of shrubland-grassland but outside the Project Site.

The affected areas and species of conservation importance are illustrated in

Figures 5.4a to 5.4m.)

Size/Abundance Permanent loss approximately 0.19 ha.






Mitigation

Low

Cultivated Land

The habitat loss of cultivated land amounts to only 0.04 ha no matter which site of San Shek

Wan Trunk SPS is selected. No species of conservation importance was recorded within the

affected cultivated land. In view of its low ecological value and artificial nature that results in

a high recreatability, it is considered that the habitat loss of cultivated land would be of low

impact significance (see Table 5.31).







5-44 B&V / ERM

Table 5.31 – Impact of Habitat Loss on Cultivated Land during Construction Phase Evaluation Criteria Cultivated Land

Habitat Quality The habitat quality is low.


importance




recorded within the habitat of cultivated land but outside the Project Site. The

affected areas and species of conservation importance are illustrated in

Figures 5.4a to 5.4m.)

Size/Abundance Permanent loss approximately 0.04 ha.



Magnitude The scale of the habitat loss and impact is very small in the context of the


Overall Impact Before Mitigation Low

Urbanised/ Disturbed Area

The habitat loss of urbanised/ disturbed area amounts to 0.22 ha no matter which site of San

Shek Wan Trunk SPS is selected. No species of conservation importance was recorded within

the affected area. In view of its low ecological value and artificial nature that results in a high

recreatability, it is considered that the habitat loss of urbanised/ disturbed area would be of

low impact significance (see Table 5.32).

Table 5.32 – Impact of Habitat Loss on Urbanised/Disturbed Area during Construction Phase Evaluation Criteria Urbanised/ Disturbed Area

Habitat Quality The habitat quality is negligible.


importance




recorded within the habitat of urbanised/ disturbed area but outside the Project

Site. The affected areas and species of conservation importance are

illustrated in Figures 5.4a to 5.4m.)

Size/Abundance Loss of approximately 0.22 ha.


Reversibility The loss of this habitat is considered reversible since the new SPSs and STW

are also part of urbansed/disturbed area.



Overall Impact Before Mitigation Low

In view of the evaluation in Tables 5.28 – 5.32, apart from the Aquilaria sinensis to be

affected by the San Shek Wan SPS (Alternative site) and San Shek Wan STW, potential

impact on the other species of conservation importance listed in Table 5.25 is not anticipated.

Potential impact on species of conservation importance found in streams is considered to be

low.

Other Impacts

Impact on Recognized Sites of Conservation Importance – The construction works of the

Project will not encroach onto any mangrove and Fung Shui woodland habitats, Lantau South

Country Park or any Ecological Important Streams occurring within the Study Area. Given

the relatively low ecological value of most of the affected area, the small scale of the Project









5-45 B&V / ERM

and no flora or fauna species recorded within the Project Site, potential impact on the Sites of

Conservation Importance is considered to be low.

Habitat Fragmentation and Isolation – The construction works will mainly be conducted

along existing roads and within residential area except some habitats such as mixed woodland,

plantation, shrubland-grassland or cultivated land. In the view of the small scale of the

Project and the availability of surrounding similar habitats, the potential impact of habitat

fragmentation and isolation on associated wildlife utilising the affected habitats is considered

to be minimal.

Noise, Human Activities and Other Disturbances – Increased human activities and

disturbances due to the Project construction have the potential to affect the surrounding

natural habitats and the associated wildlife. These potential impacts are expected to be low

given that regular checks on construction practices and boundaries will be conducted. As

there has been low level of human activities, wildlife is considered able to habituate slight

increase of disturbance. On the other hand, several mitigation measures for noise reduction

are recommended in Section 8.8 and the measures will also reduce the disturbance to wildlife.

Impacts from Emergency Discharge during Operation Phase – Emergency discharge of

raw sewage has the potential to affect the water and habitat quality nearby the safety outlet

location at mangroves of Pui O and Shui Hau, stream/channel at Tong Fuk, Cheung Fu Street,

lower Cheung Sha and San Shek Wan. These potential impacts are expected to be low given

that the emergency discharge, if occurs, would last for a very short period (2 hours) and the

possibility of its occurrence is extremely low because of sufficient preventive measures,

including standby pumps, dual power supplies and emergency storages have been proposed

for the sewage pumping stations.


The following section evaluates the impacts on marine ecological resources as a result of the

potential impacts identified in previous sections. Based upon the information presented above,

the significance of the marine ecological impact associated with the construction and

operation of the submarine outfall has been evaluated in accordance with the EIAO-TM

(Annex 8, Table 1) as follows. The outcomes of this evaluation are summarised in Table 5.33.



5-46 B&V / ERM

Table 5.33 – Marine Ecological Impacts associated with Submarine Outfall during Construction and Operation Phases

Potential

Impact Receiver

Nature of Impact Habitat

Quality Species Affected Size /Abundance Duration Reversibility Magnitude Overall

Impact

Before

Mitigation Construction Phase Habitat Loss

&

Disturbance

Subtidal Soft

Bottom Habitat

within the

dredged area

The habitat

quality is low

to moderate.

No species of

conservation

importance was

recorded within the

Study Area. Hence

no species of

conservation

importance is likely

to be impacted.

Loss of approximately

0.13 ha of seabed. Permanent due to

installation of

outfall diffuser.

Not reversible No unacceptable

impacts to benthic

assemblage are

predicted to occur.

Low

Change in

Water Quality Subtidal Soft

Bottom Habitat,

Subtidal Hard

bottom

Habitats;

Intertidal

Habitats;

Coastal/ Marine

Water habitats

in close vicinity

of the dredged

area

The habitat

quality is

generally low

to moderate,

except it is

moderate to

high for

sandflat.

All affected habitats

are of low ecological

value. Horseshoe

crab juveniles were

recorded in sandflat

while Indo-Pacific

Humpback dolphin

and Finless

Porpoises were

recorded in coastal

water

Temporary increase in

SS is expected to be

localized. Impacts on

the wider marine

environment (>1 km

away from the works

area) expected to be very

low due to gradual

deposition of SS over a

short distance.

The marine

dredging works will

approximately

continue for a

period of one

month.

Reversible No unacceptable

impacts to benthic

assemblage are

predicted to occur.

Low

Vessel

Disturbance Coastal/ Marine

Water habitats

in close vicinity

of the dredged

area

The habitat

quality is

generally low

to moderate.

Indo-Pacific

Humpback dolphin

and Finless

Porpoises were

recorded in coastal

water.

- The marine

dredging works will

approximately

continue for a

period of one

month.

Reversible With the

implementation of

marine traffic control,

potential disturbances

are expected to be

minimized

Low



5-47 B&V / ERM

Potential

Impact Receiver

Nature of Impact Habitat

Quality Species Affected Size /Abundance Duration Reversibility Magnitude Overall

Impact

Before

Mitigation Operation Phase

Operational

effluent

discharge

Subtidal Soft

Bottom Habitat,

Subtidal Hard

bottom

Habitats;

Intertidal

Habitats;

Coastal/ Marine

Water habitats

in close vicinity

of the effluent

discharge

The habitat

quality is

generally low

to moderate,

except it is

moderate to

high for

sandflat.



value. Horseshoe

crab juveniles were


while Indo-Pacific

Humpback dolphin

and Finless

Porpoises were

recorded in coastal

water

Impacts due to effluent

discharge to marine

ecological resources are

not expected as the

discharge should satisfy

the relevant requirements

of WPCO-TM effluent

discharge standards.

Long-term over the

operation of STW

Not reversible No unacceptable

impacts are thus

anticipated.

Low

Emergency

Discharge

Subtidal Soft

Bottom Habitat,

Subtidal Hard

bottom

Habitats;

Intertidal

Habitats;

Coastal/ Marine

Water habitats

in close vicinity

of the effluent

discharge

The habitat

quality is

generally low

to moderate,

except it is

moderate to

high for

sandflat.



value. Horseshoe

crab juveniles were


while Indo-Pacific

Humpback dolphin

and Finless

Porpoises were

recorded in coastal

water

A short-term

deterioration of the water

quality conditions near

the proposed outlet

location is expected, but

the water quality

conditions would quickly

recover once after the

dilution effect with

seawater and after the

termination of

emergency discharge for

both wet and dry

seasons.

The occurrence of

emergency overflow

of untreated sewage

is expected to be

highly unlikely in

place with

safeguards and

controls.

Reversible Overall ecological

impact on adjacent

habitats is considered

to be temporary and

minor after

implementation of

preventive measures.

Low



5-48 B&V / ERM

The impact assessment presented above indicates that no unacceptable impacts to various

marine ecological resources mentioned in the above sections would be expected. Although

subtidal soft bottom habitats will be disturbed due to dredging, it is expected that the seabed

will be recolonised by benthic assemblages and return to the former existing state after the

completion of the marine dredging works. As such, potential impact on the hydrodynamic

properties and hydrology is not anticipated, and impacts to marine ecological resources during

operation phase are expected to be negligible.

5.8 Mitigation Measures

General

In accordance with the guidelines in the EIAO-TM Annex 16 on ecological impact assessment,

the policy adopted in this EIA for mitigating significant impacts to ecology, in order of

priority, is:

Avoidance: Potential impacts should be avoided to the maximum extent practicable by

adopting suitable alternatives;

Minimisation: Unavoidable impacts should be minimised by taking appropriate and

practicable measures such as constraints on intensity of works operations or timing of

works operations; and

Compensation: The loss of important species and habitats may be provided for

elsewhere as compensation. Enhancement and other conservation measures should

always be considered whenever possible.

Avoidance

The above impact assessment demonstrates that the Project will avoid encroachment into any

habitat of high ecological value during its construction, particularly to those key ecological

sensitive receivers such as Lantau South Country Park and EISs at Tong Fuk and Pui O.

Direct impacts on plant and wildlife species of conservation importance will also be avoided

as far as practicable during the detailed design. Permanent building structures, works and

storage areas have avoided in the habitat of high ecological value, as well as the proximity of

species of conversation importance (e.g. Aquilaria sinenis).

Construction impacts to marine ecological resources (i.e. natural rocky shore and subtidal

hard bottom habitats) and marine sensitive receivers (i.e. Shui Hau sandflat) have largely been

avoided by applying the HDD method for installing submarine outfall pipeline and through

proper planning design and execution of the works (i.e. optimisation of project construction

schedule/ sequence, using good engineering/ industry practice, timely completion of

construction works to reduce impact duration, etc.).

Indirect impacts on marine sensitive receivers due to the dispersion of sediment plume can be

avoided as the dredging works will be designed to confirm compliance with the assessment

criteria at sensitive receivers and control water quality impacts to within acceptable levels, an

water quality mitigation measures will be developed and implemented when required to

further avoid/ reduce potential impacts (See Section 4).

To summarise, this initial assessment of impacts demonstrates that impacts will largely be

avoided during the construction and operation of the proposed Project, particularly to the key

terrestrial and marine ecological sensitive receivers through the avoidance of direct and



5-49 B&V / ERM

indirect impacts to ecological sensitive habitats and wildlife/ species of conservation

importance.

Minimisation

As part of the site selection process, three sewage pumping stations at Sha Tsui, Ham Tin and

Pui O Beach and a separate effluent pumping station initially at the coastal area of San Shek

Wan were deleted from the proposed sewerage scheme to minimise the overall footprint and

hence habitat loss and vegetation removal associated with the Project.

Trenchless construction method will be considered wherever necessary for laying the

proposed sewers. When the proposed pipepasses the EIS at Tong Fuk, the pipe laying will

adopt a bridge-mounted method without disturbing the stream bottom and riparian vegetation

along stream banks. Since there is sufficient headroom under the bridges, the pipes would not

touch the stream water. For the proposed gravity sewer across the EIS at Pui O, the pipe will

be laid by pipe-jacking method in which a jacking pit and a receiving pit will be constructed

on the land adjacent to the stream and about 0.5 m diameter of pipe will be jacked from the

jacking pit to the receiving pit without disturbing the stream and riparian vegetation as the pits

are located at sufficient distance (at least 5 m) from the stream banks and the surrounding

areas are free from riparian vegetation. The pipe will be constructed underground below the

Pui O EIS and kept clear distance at least 2 m below the stream bed. The implementation of

pipe laying works by using pipe-jacking method will be scheduled to dry season. The

construction and operation of the pipe will not cause change in water level as the substratum

above the tunnel and the tunnel will be impervious to gravitational flows of stream water. As

the scale of works (i.e. the pipe is at 0.5 m in diameter and 5 m long) is small and there will be

sufficient distance below the stream bed, the vibration arisen from the pipe-jacking is minor.

By using such construction method as well as the implementation of good practice to control

site run-off (see Section 4.9.1 for detailed mitigation measures to control construction site

runoff and drainage), the potential impact on the water table and ecology of the EIS is

predicted to be minor. By using such construction method as well as the implementation of

good construction practices, the potential impact on these EISs and other sites of conservation

importance will be minimised.

The present alignment of trunk sewers and rising mains overlaps with the main roads and

accesses of South Lantau. The sites of the proposed and alternative SPSs and STW will be

located within disturbed area as much as practicable. If habitats such as plantation,

shrubland-grassland and cultivated land are unavoidably affected, only the lands in close

vicinity to developed area will be taken to minimise the habitat fragmentation and isolation

arising from the construction of Project.

The above impact assessment demonstrates that the present alignment of the submarine

outfall is representing the shortest length (straight line of approximately 1,100 m long) to

avoid direct impacts on marine ecological resources. By having such alignment, the potential

impacts onto the subtidal hard and soft bottom habitats will be minimised.

Moreover, the use of HDD method is particular suitable for the construction of the proposed

submarine outfall from the STW because marine dredging and excavation would be minimal

(dredging area is estimated to be 39m x 33m around the diffuser) compared with conventional

submarine outfall pipeline installation methods (dredging area is about 16m wide x 1100m

long along the outfall), during which a trench in seabed is needed to be formed along the

entire alignment and backfilling is required after pipe laying. This HDD method will

minimise the potential impacts on water quality and marine ecological resources.



5-50 B&V / ERM

To minimize the other disturbances of the construction works to the surrounding habitats and

associated wildlife, the following appropriate construction practices should be implemented as

far as practicable.

Erect fences along the boundary of the works area before the commencement of works to

prevent vehicle movements and encroachment of personnel onto adjacent areas;

Regularly check the work site boundaries to ensure that they are not breached and that

damage does not occur to surrounding areas;

Avoid any damage and disturbance, particularly those caused by filling and illegal

dumping, to the surrounding habitats through proper management of waste disposal;

Reinstate temporarily affected areas, particularly the habitats of plantation and shrubland-

grassland immediately after completion of construction works, through on-site tree/shrub

planting. The tree/shrub species will be chosen with reference to those in the surrounding

area (See Annex 5B – Table A2); and

A closed grab dredger will be used to dredge down about -11mPD which is approximately

6m below the current seabed and there will be no excessive dredging.

For emergency discharge in operation phase, an Emergency Response Plan shall be prepared

and implemented to cope with emergency discharge of untreated sewage. In brief, standby

facilities (i.e. main treatment units and accessories/ equipment parts) and dual power supply

(if dual power supply is available) would be provided to secure electrical power supply. In

addition, adequate emergency storage for SPSs and STW (see Sections 3.4.1 – 3.4.2) will be

provided. Regular inspection and maintenance should be carried out to prevent equipment

failure by a maintenance crew organized by DSD/ST2 - regular inspection team which will

station in San Shek Wan STW. Existing mobile team (except regular inspection team of

DSD) from Ma Wan STW will be responsible to backup the regular team in non-office hours.

Emergency team (except regular inspection team and existing mobile team of DSD) will assist

the existing mobile team to handle the situation in order to reduce the maintenance time in

non-office hour. Relevant government departments including EPD, LCSD and DSD shall be

informed by the STW operator as soon as possible of any emergency discharge of untreated

sewage. DSD is committed to repair the STW and SPSs as soon as practicable usually within

6 hours including time of travelling and repairing.

Compensation

Approximately of 0.52 to 0.55 ha of mixed woodland with moderate ecological value will be

lost due to construction of the San Shek Wan STW, San Shek Wan SPS (Proposed and

Alternative Sites) and their associated access roads. The loss of mixed woodland will be

compensated at suitable areas within the site boundary of the San Shek Wan STW and its

close proximity (Figure 5.9a & Figure 5.9i). Approximately, a total of 1.11 ha will be

compensated through compensatory woodland (Table 5.34).

Table 5.34 – Approximate Area of Compensatory Woodland Location Loss of Mixed Woodland (ha) Compensatory Woodland (ha)

San Shek Wan STW 0.38 0.11

Shui Hau Trunk SPS - -

Tong Fuk Trunk SPS - -

Cheung Fu Street Trunk SPS - -


../Figures/5.9a.pdf

../Figures/5.9i.pdf



5-51 B&V / ERM

Location Loss of Mixed Woodland (ha) Compensatory Woodland (ha)

Cheung Sha Trunk SPS - -

San Shek Wan (Proposed) 0.14 -

San Shek Wan (Alternative)* 0.17 -

Pui O SPS - -

Proposed area for woodland compensation –

hillside to the southwest of San Shek Wan

STW

- 1

Total Area (ha) 0.52 to 0.55* 1.11

*Note:

Area of Woodland Loss at Proposed San Shek Wan SPS = 0.52 ha

Area of Woodland Loss at Alternative Site of San Shek Wan SPS = 0.55 ha

Within the site boundary of the San Shek Wan STW about 0.11 ha of land will be reserved for

planting as a compensatory woodland. An area of approximately 1 ha of hillside to the

southwest of the San Shek Wan STW will be established by the project proponent (i.e. DSD)

or its engaged consultant/ contractor as a compensatory woodland. This area is on a gently

sloping hillside (approx. 12 – 14 in degree) and is identified as shrubland-grassland habitat. It

is considered that this area is suitable for woodland compensation, providing connectivity to

existing mixed woodland in the area. Also this hillside area in general does not require

clearance of existing woodland and exotic species can be selectively removed if

needed. During tree planting for woodland compensation, existing native trees and shrubs in

the planting area will be preserved as far as possible. Planting near roadside and within the

nearby woodland area will be avoided. The project proponent (i.e. DSD) will be responsible

for the establishment and maintenance of approximately 1.11 ha compensatory woodland area

during the first 10 years of its establishment. It is expected that after 10 years, with proper

maintenance the woodland would be self-sustained and will be passed to relevant government

department (e.g. Lands Department) for maintenance per existing arrangement for

government land. Overall, the loss of up to 0.55 ha of mixed woodland from the Project is

proposed to be compensated in areas of about two times of the areas affected (about 0.11 ha

around the San Shek Wan STW and 1 ha in the hillside to the southwest of San Shek Wan

STW). Details for the compensatory woodland planting will be developed in a woodland

compensation proposal as part of the EM&A programme, in which the boundary of the

proposed woodland compensation area will be further refined.

Species proposed for planting are pioneer native tree and shrub species often present in

natural woodlands in the Study Area, including a number of shrub species know to be of value

in providing food for native fauna. Location for the proposed compensatory woodland is

illustrated in Figure 5.9a and Figure 5.9i. Proposed native species for woodland

compensation include:

Native trees:

Alangium chinense

Celtis sinensis

Mallotus paniculatus

Native shrubs:

Ilex asprella

../Figures/5.9a.pdf

../Figures/5.9i.pdf



5-52 B&V / ERM

Melastoma candidum

Psychotria asiatica

For the trees of Aquilaria sinensis found in the San Shek Wan SPS (Alternative site) and San

Shek Wan STW, transplantation plan will be developed accordingly. Trees shall be retained

and transplanted where practical, prime location would be at the compensatory woodland at

San Shek Wan STW.

Since habitat loss due to other land-based construction and marine dredging works for laying

the submarine outfall of the Project only occurs on the habitats of low or low to moderate

ecological value, where no species of conservation importance were recorded. Given that the

scale of marine works has been significantly reduced by adopting the HDD construction

method and the impact severity is evaluated to be low, other specific mitigation measure

including ecological compensation is not required from the marine ecology point of view.

5.9 Cumulative Ecological Impact

A number of interfacing projects in southern Lantau area is summarized as follows.

PWP No. 257WC – Siu Ho Wan Water Treatment Works Extension – Pui O Raw Water

Pumping Stations and Associated Mainlaying (WSD/Design)

Agreement No. CE 38/2007 (CE) – Planning and Engineering Study of Private Housing

Development at Cheung Sha, Lantau – Feasibility Study (CEDD/HKI&I)

Agreement No. CE 11/2008 (WS) – Replacement and Rehabilitation of Water Mains

Stage 4 (WSD/CM)

CE 29/2008 (EP) – Engineering Investigation and Environmental Studies for Integrated

Waste Management Facilities Phase 1 – Feasibility Study (EPD/IP)

Agreement No. 4600003274 – Cable Route Consultancy Services along Chi Ma Wan Road

(CLP)

RPIS IS009 – Construction of Vehicular Access at Pui O San Wai Tsuen, Lantau Island

(HyD/Works)

RPIS IS005 – Construction of Car Park at Pui O, Lantau Island (HyD/Works)

Agreement No. CE 15/2010 (DS) – Upgrading of Cheung Chau and Tai O Sewage

Collection, Treatment and Disposal Facilities (DSD/CM)

Agreement No. 4600003274 – Cable Route Consultancy Services along Chi Ma Wan Road

(CLP)

However, due to unavailable/ non-overlapping project programme or sufficient distance away

from the current Project Site, none of these projects is considered as concurrent projects of

this Project (Section 3.7). Moreover, all these projects will implement necessary mitigation

measures to minimise potential ecological impacts. Therefore associated cumulative

ecological impact is not considered to be significant.



5-53 B&V / ERM

5.10 Residual Impact

As a result of land-based construction activities, up to 0.52 to 0.55 ha mixed woodland, 0.20

ha of plantation, 0.19 ha of shrubland-grassland, 0.04 ha of cultivated land and 0.22 ha of

urbanised/disturbed area would be permanently lost due to the Project. The affected habitats

are considered to be of low or low to moderate or moderate ecological values. With the

implementation of the recommended mitigation measures discussed in Section 5.8, the loss of

mixed woodland and trees of the protected plant species Aquilaria sinensis will be

compensated and transplanted, respectively. It is anticipated that all

potential ecological impacts will be reduced to an acceptable level. Therefore, no adverse

residual impact due to the construction of proposed sewers, rising mains, SPSs and STW is

expected from the aspect of terrestrial ecology.

In terms of marine-based construction works, approximately 0.13 ha of subtidal soft bottom

habitats of low to moderate ecological value will be lost due to the marine dredging activity.

No unacceptable residual impacts are anticipated as these habitats.

5.11 Environmental Monitoring & Audit (EM&A)

Terrestrial Ecology

Woodland compensation to mitigate for the loss of mixed woodland due to the construction of

the San Shek Wan STW, San Shek Wan SPS (Proposed and Alternative Sites) and their

associated access roads is recommended to fully compensate the loss of mixed woodland.

Establishment and after-establishment caring measures of the compensatory mixed woodland

are proposed for this Project. Details for the woodland compensation, including planting

species, will be developed in a woodland compensation proposal as part of the EM&A

programme.

For the affected individuals of Aquilaria sinensis at San Shek Wan SPS Alternative Site and

STW, transplantation plan will be developed, including an EM&A programme for monitoring

the transplantation of the tree individuals.

Marine Ecology

Construction Phase

During the construction phase, the following EM&A measures will be undertaken to verify

the predictions in the EIA and ensure the environmental acceptability of the construction

works. Water quality impacts will be monitored and checked through the implementation of a

Water Quality EM&A programme (refer to Section 4 for details). The monitoring and control

of water quality impacts will also serve to avoid unacceptable impacts to marine ecological

resources.

Operation Phase

The assessment presented above indicates that unacceptable operation phase impacts are not

expected to occur to marine ecological resources. No marine ecology specific operational

phase monitoring is considered necessary. The monitoring and control of water quality will

also serve to avoid unacceptable impacts to marine ecological resources.



5-54 B&V / ERM

5.12 Conclusions

This Section of the EIA has described the potential terrestrial and marine ecological impacts

associated with the construction and operation of the Project in South Lantau. The purpose of

the assessment is to evaluate the acceptability of predicted impacts to terrestrial and marine

ecological resources and sensitive receivers. Findings of literature review and dedicated

baseline field surveys have provided information for the evaluation of species of conservation

importance and ecological importance of various habitats within the Study Area as well as in

the Project Site.

A total of 15 habitat types were identified within the Study Area. They are terrestrial habitats

(i.e. Fung Shui woodland, mixed woodland, plantation, shrubland-grassland, cultivated land,

marsh, stream/channel and urbanised/disturbed area) and coastal habitats (i.e. sandflat,

mangrove, rocky shore, sandy shore, subtidal hard bottom and soft bottom habitats and

coastal/ marine waters), among which Fung Shui woodland, marsh, stream/ channel,

mangrove and sandflat are of moderate to high ecological value; mixed woodland is of

moderate ecological value, plantation, shrubland-grassland, rocky shore, subtidal soft bottom

and coastal/ marine waters are of low to moderate ecological value; cultivated land,

urbanized/ disturbed area, sandy shore and subtidal hard bottom are of low ecological value.

Apart from this, a number of recognized ecologically important / sensitive sites are located

within the Study Area. These include Lantau South Country Park, Coastal Protection Area,

Green Belt, the mangroves in Pui O, Fung Shui woodlands in Tong Fuk and Shui Hau,

proposed SSSI in Shui Hau Wan, Ecologically Important Streams (EIS) in Pui O and Tong

Fuk and horseshoe crab nursery ground in Shui Hau.

Regarding to species of conservation importance, seven flora species (i.e. Incense Tree

Aquilaria sinensis, Hong Kong Pavetta Pavetta hongkongensis, Silver-back Artocarpus

Artocarpus hypargyreus, Water Shamrock Marsilea quadrifolia, Water Spangles Salvinia

natans, Luofushan Joint-fir Gnetum luofuense and Zoysia sinica), one mammal species (i.e.

Japanese Pipistrelle Pipistrellus abramus), five bird species (i.e. Reef Egret Egretta sacra,

Black Kite Milvus migrans, Collared Scops Owl Otus lettia, Greater Coucal Centropus

sinensis and Hwamei Garrulax canorus), one amphibian species (i.e. Chinese Bullfrog

Hoplobatrachus chinensis), one reptile species (i.e. Copperhead Racer Elaphe radiata), seven

fish species (i.e. Japanese eel Anguilla japonica, Predaceous Chub Parazacco spilurus, Eye-

spotted puffer Takifugu ocellatus, Sleepy goby Psammogobius biocellatus, Indo-pacific

tropical sand goby Favonigobius reichei, Small snakehead Channa asiatica and Spotty band

goby Glossogobius olivaceus), one crustacean species (Pseudosesarma patshuni), one hard

coral species (i.e. Oulastrea crispata) and one Horseshoe Crab species (i.e. Tachypleus

tridnetatus) were recorded during the field baseline surveys. But none of these species were

found within the Project Site, except for the Incense Tree Aquilaria sinensis which was

recorded at San Shek Wan SPS Alternative Site and San Shek Wan STW. During the

construction phase, construction activities may cause direct ecological impacts including

habitat loss and vegetation removal, whereas indirect impacts on wildlife include the changes

in water quality. Potential impacts of increased human activities and other disturbances due

to the Project construction would not be significant provided that regular checks on

construction site practices and boundaries will be conducted. In addition, in the view of the

availability of surrounding similar habitats, the potential impact on wildlife especially on the

species of conservation importance as a result of habitat fragmentation and isolation is

considered to be minimal.

Habitat loss, which is the main terrestrial ecological impact arising from the Project, will

primarily occur in habitats of low and low to moderate ecological values, and approximately



5-55 B&V / ERM

0.52 – 0.55 ha of mixed woodland of moderate ecological value will be lost due to the

construction of the Proposed/ Alternative Site of San Shek Wan SPS and San Shek Wan STW

including their associated access roads. Impact to mixed woodland and associated flora of

conservation importance (the Incense Tree Aquilaria sinensis) will be compensated by

woodland compensation and transplantation. For marine ecological impact, habitat loss/

disturbance of subtidal soft bottom habitat which is of low ecological value (within the

Project footprint) will also arise from minor marine dredging activity for installing the

submarine diffuser and there will be potential burial of benthic organisms. Potential impacts

on subtidal hard bottom habitat (including corals) will be impacted temporarily due to the

deterioration of water quality arisen from minor marine dredging works. And for the sites of

conservation importance, most of these sites within the Study Area will not be affected by the

Project.

With the implementation of the proposed mitigation measures, no adverse residual impact due

to the land-based and marine-based construction of proposed sewers, rising mains, SPSs and

STW and submarine outfall is expected.

5. ecological impact assessment 5.1 introduction 5 · 2016-11-17 · outline zoning plan as coastal...

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