10                LANDSCAPE AND VISUAL IMPACT ASSESSMENT

 

Introduction

 

10.1          This section presents the Landscape and Visual Impact assessment of the Proposed Sewage Collection, Treatment and Disposal development at Sok Kwu Wan (hereafter called the “Project”) and outlines the potential impacts to the existing landscape and visual context of the area together with the mitigation measures proposed to alleviate those impacts.  The assessment has been carried out in accordance with the Environmental Impact Assessment Ordinance Technical Memorandum.

 

Background and Options

 

10.2          The Project is one of the designated sewerage planning areas of the Outlying Islands Sewerage Master Plan, December 1994.  The intention of the Project is to improve the poor water quality at the Picnic Bay.  Currently, the untreated waste water is directly discharged to the inner Sok Kwu Wan.  The bay is visited and used regularly for pleasure craft, and there is also fish culture zones in the bay.    Without the Project, the water quality will continue to depreciate which will lead to a devaluation of the recreational quality of Sok Kwu Wan.  Furthermore, the low dissolved oxygen concentration in the poor water will kill the fishes in the culture zones.

 

10.3          Sewerage Improvement Works for Sok Kwu Wan is under Package J of the Stage I Phase II works.  The construction of the Project is proposed to commence in December 2004 and complete by August 2007.

 

Options

 

10.4          Two preliminary schemes under Option 1 (local treatment and discharge through a long outfall to the entrance of the bay) were proposed for the Project (refer to Chapter 2 for descriptions of different options).  These were:

 

Ÿ         Scheme 1 (Sewerage Master Plan –  SMP Option)

Ÿ         Scheme 2 (Recommended Option)

 

10.5          The major difference in the source of landscape and visual impacts between the two schemes is the location of the proposed Sewage Treatment Works (STW); other impacts are similar.  In Scheme 1 the proposed location is at the coastline where reclamation works is required, and its view is open to a wide angle. In Scheme 2 the proposed location is at the disused quarry where existing vegetation partially screen the site when travelling on water.  The proposed STW at the disused quarry is a more favorable location, and it serves as the basis for this assessment. 


Project Description

 

10.6          Further studies on cost effectiveness, engineering issues and land issues lead to the recommended scheme.  Its components include (refer to Figure 10.1 for sewerage alignment and components):

 

Ÿ         construction of two Pumping Station P1s (P1A and P1B) located east and west of the pedestrian bridge (each P1A and P1B comprises a pumping station, deodourizer, standby generator and control kiosk).

Ÿ         construction of rising main sewer (exposed) over existing bridge (approximately 20m in length).

Ÿ         construction of underground gravity sewers aligned existing footpaths and through the Sok Kwu Wan First Street and side streets to Pumping Station P2.

Ÿ         construction of Pumping Station P2 behind the football court at the base of the disused quarry (P2 comprises a pumping station, deodourizer, standby generator and control kiosk).

Ÿ         a rising main sewer (underground) aligned the seaward edge of the footpath to STW.

Ÿ         construction of STW  located at the disused quarry alongside the coastal footpath; and

Ÿ         construction of a rising main sewer along the coastline to the submarine effluent outfall (approximately 710m in length).

Ÿ         Total length of gravity sewer is approximately 1,400m.

 

 

Approximate Dimension (m)

Site Area

 

Length

Width

Height*

 

P1A

 

202.5m2

Pumping Station

11.85

4.0

300mm

14.22m2

Deodourizer

3

1

3

9m2

Standby Generator

5

4.5

3.5

70m2

Control Kiosk

2.6

1.5

1.5

5.85m2

P1B

 

241 m2

Pumping Station

11.85

4.0

300mm

14.22m2

Deodourizer

3

1

3

9m2

Standby Generator

5

4.5

3.5

78.75m2

Control Kiosk

2.6

1.5

1.5

5.85m2

P2

 

310 m2

Pumping Station

11.85

4.0

300mm

14.22m2

Deodourizer

3.5

1.5

3.2

9m2

Standby Generator

5

6

3.5

105m2

Control Kiosk

2.6

1.5

1.5

5.85m2

STW

Refer to Figure 10.13 for layout

Refer to Figure 10.13 for layout

7.0m max.

1529 m2

Note: *         Height above ground level

 

 

 

10.7           Key issues relating to the impact on the landscape and visual context of the Project include:

 

Construction Phase

(i)                          loss of vegetation (a separate tree survey has been compiled);

(ii)                         presence of construction machinery;

(iii)                       open trenches during installation;

(iv)                       construction of pumping stations and STW;

(v)                        slope stabilization works; and

(vi)                       construction traffic on site.

 

Operation Phase

(i)                          addition of built elements in the existing environment context, i.e. pumping stations and STW; and

(ii)                         the finishes of the disturbed slope.

 

Initial Comments

 

10.8          Consultations with the South Lamma Rural Committee, Lamma Area Committee and Island District Council were carried out (refer to section 2.59).  Concerns include visual impacts associated with the pumping stations and sewage treatment works.  Initial comments and consultation from Planning Department has also been sorted.  There was strong objection towards the location of the STW at the coastline in Scheme 1.  Furthermore, vegetation loss, soft landscape and finishes to the STW are some of the key issues that should be addressed in the report.

 

Assessment Methodology - General

 

10.9          The landscape and visual impact of the proposed sewage collection, treatment and disposal development at Sok Kwu Wan are considered separately, where:

              

Ÿ             landscape impact assessment shall assess the source and magnitude of developmental effects on the existing landscape elements, character and quality in the context of the site and its environs and;

Ÿ             visual impact assessment shall assess the source and magnitude of development effects on the existing views, visual amenity, character and quality of the visually sensitive receivers within the context of the site and its environs.

 

Assessment Methodology for Landscape Impacts

 

10.10      The procedures for assessing landscape impacts during both construction and operation phases would involve:

 

1)      Description of Landscape Baseline Conditions.

 

10.11      The data collected on the landscape conditions will form the basis against which to review the significance of the predicted landscape impacts of the Project.  In order to establish the landscape baseline, landscape character areas (LCAs) and landscape resources (LSs) are identified.  The Study Area will be within 500m from the work limit.

 

2)      Assessment of the degree of sensitivity of the LCAs and LRs.

 

10.12      Factors affecting the sensitivity of receivers for the evaluation of the landscape impacts:

 

·        Quality of landscape characters/resources,

·        Importance and rarity of special landscape elements,

·        Ability of the landscape to accommodate change,

·        Significance of the change in local and regional context, and

·        Maturity of the landscape.

 

The degree of receiver sensitivity is classified as low, medium or high.

 

3)      Identification of potential sources of landscape impacts. 

 

10.13      The key sources of construction works and operation procedures that would generate landscape impacts will be identified.  Prediction of impacts can be adverse/beneficial and irreversible/reversible.

 

4)       Assessment of potential magnitude of change.

 

10.14      Factors affecting the magnitude of change for assessing landscape impacts:

 

·        Compatibility of the Project with the surrounding landscape,

·        Duration of impacts under construction and operation phases,

·        Scale of development, and

·        Reversibility of change.

 

The magnitude of change is classified as negligible, small, intermediate or large.

 

10.15      Landscape impacts are defined as a function of the sensitivity of receiver and the magnitude of change to that receiver’s view.  The matrix below was used to evaluate the significance of landscape impacts.

 


Magnitude of Change

Large

Moderate Impact

Moderate/

Significant Impact

Significant Impact

Intermediate

Slight/Moderate Impact

Moderate Impact

Moderate/

Significant Impact

Small

Slight Impact

Slight/Moderate Impact

Moderate Impact

Negligible

Negligible

Negligible

Negligible

 

Low

Medium

High

                                                                                                        Sensitivity of Receiver

 

5)      Identification of potential landscape mitigation measures.

 

10.16      The identification of the landscape impacts will highlight those sources of conflict requiring landscape design solutions to reduce adverse impacts.  Mitigation measures may include appropriate construction procedures, revisions/refinement to the engineering design, the implementation of compensatory planting and/or hard landscape design to minimise adverse impacts and to bring about potentially beneficial long term landscape impacts.

 

6)      Summary of Landscape Impact Assessment

 

10.17      This section summarises the results and provides the evaluation of landscape impact.

 

Assessment Methodology for Visual Impacts

 

10.18      The procedures for assessing visual impacts during both construction and operation phases involve:

 

1)      Description of Visual Baseline Conditions.

 

10.19      The data collected on the visual conditions will form the basis against which to review the significance of the predicted visual impacts of the Project.  In order to establish the visual baseline, key Visual Sensitive Receivers (VSRs) within the visual envelop are identified.  These are the people who would reside within, work within, play within or travel through the vicincity of the Project. 

 

2)      Assessment of the degree of sensitivity f the VSRs.

 

10.20      Factors affecting the sensitivity of receivers for the evaluation of the visual impacts:

 

·        Value and quality of existing views,

·        Availability and amenity alternative views,

·        Type and estimated number of receiver population,

·        Duration or frequency of view, and

·        Degree of visibility.

 

The degree of receiver sensitivity is classified as low, medium or high.

 

3)      Identification of potential sources of visual impacts. 

 

10.21      The key sources of construction works and operation procedures that would generate visual impacts will be identified.  Impacts can be adverse/beneficial and irreversible/reversible.

 

4)       Assessment of potential magnitude of change.

 

10.22      Factors affecting the magnitude of changes for assessing visual impacts:

 

·        Compatibility of the project with the surrounding landscape,

·        Duration of impacts under construction and operation phases,

·        Scale of development,

·        Reversibility of change,

·        Viewing distance, and

·        Potential blockage of view.

 

The magnitude of change is classified as negligible, small, intermediate or large.

 

10.23      Visual impacts are defined as a function of the sensitivity of a receiver and the magnitude of the change to that receiver’s view.  The matrix below was used to evaluate the significance of visual impacts.

 

Magnitude of Change

Large

Moderate Impact

Moderate/

Significant Impact

Significant Impact

Intermediate

Slight/Moderate Impact

Moderate Impact

Moderate/

Significant Impact

Small

Slight Impact

Slight/Moderate Impact

Moderate Impact

Negligible

Negligible

Negligible

Negligible

 

Low

Medium

High

                                                                                                        Sensitivity of Receiver

 

5)      Identification of potential visual mitigation measures.

 

10.24      The identification of the visual impacts will highlight those sources of conflict requiring landscape design solutions to reduce adverse impacts.  Mitigation measures may include revisions/refinement to the engineering design and/or the implementation of landscape design measures including screen tree planting, hard landscape design to minimise adverse visual impacts and to bring about potentially beneficial long term visual impacts.

 


6)      Summary of Visual Impact Assessment

 

10.25      This section summarises the results and provides the evaluation of visual impact.

 

Baseline Survey

 

Site Location and Environs

 

10.26      Sok Kwu Wan, overlooking the water bodies of Picnic Bay and Tung Pok Liu Hoi Hap (East Lamma Channel), is one of the two main settlement areas of Lamma Island.  The study area is a enclosed bay located along the eastern coastline of Lamma Island at Picnic Bay.  It faces the existing Lamma Quarry to the north and Hong Kong Island to the northeast.  This coastal area is backed by steep vegetated hillside, comprising pockets of semi-mature woodland to the base of slopes gradually merging with shrubland/grassland up-slope. 

 

Landscape Baseline Conditions

 

10.27      For the purposes of this study three landscape character areas (LCAs) and one landscape resource (LS) have been identified and assessed.  (refer to Figure 10.1)  These are:

 

Ÿ         Sheltered Coastline Area (LCA1)

Ÿ         Sok Kwu Wan Restaurant/Retail Area (LCA2)

Ÿ         Exposed Coastline Area (LCA3)

Ÿ         Vegetation (LS1)

 

>         Sheltered Coastline Area – LCA1 (Refer to Figure 10.4 Photo 1, 2, 3,4,5,6)

 

10.28      The Sheltered Coastline Area is located within the southwest section of the study area.  The area is a steeply sloped, vegetated valley with an alluvial plain at its base, abutting Picnic Bay.  At the higher level of the area, Chung Mei Village, scatters some low-rise residential units (approximately 15 units).  The base of the valley comprises low-rise residential units (approximately 10 units), and a BBQ restaurant.  The residential units at the base are generally three storeys high, of concrete construction and utilitarian design.  The residential units higher in the valley are generally single storey traditional village houses.  The BBQ restaurant lies north of the residential units on the east side of the valley overlooking Picnic Bay.  The east and west side of the valley is connected by a concrete bridge.

 

10.29      The lower area of the slopes comprises woodland with semi-mature species such as Bambusa spp. Celtis sinensis, Mallotus paniculatus, Macaranga tanarius and Sterculia lanceolata ranging in height from 3 to 10 metres.  As the topography rises, the woodland gradually merges to form established shrubland/grassland, ranging in height from 1 to 3 metres.

 

10.30      The landscape value of the Sheltered Coastline Area is medium.

 

>         Sok Kwu Wan Restaurant / Retail Area – LCA2 (Refer to Figure 10.4 Photo 7, 8, 9, 10, 11)

 

10.31      Sok Kwu Wan is famed for its open-air seafood restaurants lining the waterfront.  The Sok Kwu Wan Restaurant / Retail Area lies immediately north of the Sheltered Coastline Area.  A 150 years old Tin Hau temple is located to the southern most section of the area on the perimeter of a large concrete paved open space.  Continuing northwards is the commercial and residential center of Sok Kwu Wan Village at the base of the vegetated slope.  The village has two main streets running along the Sok Kwu Wan promenade – First Street and Second Street.  First Street is accessible from the ferry pier and the footpath and is lined with restaurants with semi-outdoor seating overlooking Picnic Bay.  The seating is sheltered under steel truss canopies and canvas / polythene shutters.  Second Street, east of First Street, is lined with three storeys high residential units of concrete construction and utilitarian design.

 

10.32      An amenity open space area enclosed by a disused quarry lies in the northern section of the Restaurant/Retail Area.  The amenity area comprises seating, children’s play area, amenity tree and shrub planting, basketball court and a football field.  The surface of the children’s play area is safety matting and the surface of the two ball courts comprises rendered, painted concrete.  The amenity tree and shrub planting within the amenity open space comprise ornamental type species, such as Albizia lebbeck, Bauhinia spp., Ficus microcarpa, Macaranga tanarius, Plumeria rubra acutifolia, Codiaeum spp. and Ervatamia diviracata.  The disused quarry has a naturally regenerated vegetative cover of scrubs and climbers.

 

10.33      The topography and vegetation to the back of the Sok Kwu Wan Village is a continuation of the vegetation within the Sheltered Coastline Area.

 

10.34      The landscape quality of the Sok Kwu Wan Restaurant / Retail area is medium.

 

>         Exposed Coastline Area – LCA3 (Refer to Figure 10.4 Photo15)

 

10.35      Continuing northwards from the Sok Kwu Wan Restaurant/Retail Area is the Exposed Coastline Area.  The main feature within this area is the paved footpath that runs along the coastline leading to Mo Tat Wan Village.  On the southern section along the footpath, lies a waterfront restaurant overlooking Picnic Bay.  Approximately 400 metres east of the restaurant lies a disused quarry which is sparsely vegetated with shrubs and grasses ranging from 1 to 3 metres. 

 

10.36      Both sides of the coastal footpath is mainly vegetated with scrubs and grasses.

 

10.37      Sporadic groups of trees are located along the footpath as well, but they are generally more prominent in the lower lying areas than on the higher areas.  South of the footpath comprises steep slopes where some are densely vegetated with scrubs and grasses, and some areas display bare rock outcrop or shotcrete surface.  North of the footpath which leads to the lower lying coastline is steeply sloped and is densely vegetated with scrubs, grasses and sporadic groups of trees; these tree species comprise young and semi-mature species, such as Bridelia monoica, Celtis sinensis, Litsea spp., Microcos paniculatus, Schefflera octophylla and Rhus spp.  The coastline along the exposed coastal area comprises some rocky beaches and dense salt tolerant vegetation which provides a vegetative buffer to the lower slopes.

 

10.38      The landscape quality of the Exposed Coastline Area is medium.

 

>          Vegetation – LS1

 

10.39      The landscape resource that is more sensitive to construction and operation practices is vegetation.  The three broad classifications within this category are woodland (5.10ha), shrubland/grassland (23.80ha), and cultivation (1.0ha).  The description of the vegetation has been briefly described in the above sections on LCAs (also refer to the Ecological Impact Chapter 8).  In addition, a separate tree survey has been compiled identifying the trees within the proximity of the works area excluding those with trunk diameter less than 95mm. 

 

10.40      The landscape resource, vegetation, has an overall medium landscape sensitivity.

Visual Baseline Conditions

 

Visual Envelope

 

10.41      To the south, east and west of the study area the visual envelope is contained by the steep vegetated hillsides.  To the north, the envelope extends to the Lamma Quarry and to the water of East Lamma Channel.  (Refer to Figure 10.2)

 

Existing Visually Sensitive Receivers

 

10.42      The existing topography and vegetation along the western and eastern sections of the study area results in most views towards the scheme being well screened.

 

10.43      The visual receiver groups and their existing views are as follows: (Refer to Figure 10.2 for their locations.)

 

Ÿ         Primary Low Rise Residential / Retail -      VSR1 (Refer to Figure 10.4 Photo 8,9)

 

10.44      Included within this group are the residents and operators of the restaurant / retail frontage along First Street and Second Street of Sok Kwu Wan Village.

 

10.45      Existing views are towards Sok Kwu Wan Bay, the fish culture zones, Lamma Quarry, First Street and Second Street.  The views to the south are of the steep vegetated hillside.  The visual sensitivity is medium.

 

Ÿ         Secondary Low Rise Residential - VSR2 (Refer to Figure 10.4 Photo 1,4)

 

10.46      Included within this group are residents of low-rise residential blocks located to the east and west of the existing footbridge.

 

10.47      Views from the secondary low-rise residential areas are of the surrounding hillsides, Lamma Quarry over Picnic Bay, fish culture zones and vegetated hillsides to the south.  The visual sensitivity is medium.

 

Ÿ         Restaurants alongside Coastal Footpath - VSR3 (Refer to Figure 10.4 Photo 7,8)

 

10.48      Views are primarily seaward over Picnic Bay and its fish culture zones and onwards to Lamma Quarry.  The visual sensitivity is medium.

 

Ÿ         Pedestrian - VSR4

10.49      A pedestrian footpath extends from the western section of the study area to the eastern section, which passes through Sok Kwu Wan Village to Mo Tat Wan.  This pathway traverses the approximate alignment of the proposed works.  The western section footpath in the most part has views over Picnic Bay.  The footpath extends through Sok Kwu Wan Village and rises to the east with the natural topography.  The eastern section of the footpath is vegetated both sides with shrubland, grassland and some sporadic stands of trees, although views out to the ocean are experienced.  The visual sensitivity of pedestrian views is medium.

 

Ÿ         Boat Travelers - VSR5 (Refer to Figure 10.4 Photo 8,14)

 

10.50      Transportation to Sok Kwu Wan is mainly by boat.  Entering Picnic Bay towards Sok Kwu Wan ferry pier, the main view includes the fish culture zones and the waterfront restaurants in the foreground with the vegetated hillsides and rocky coastline in the background.  The visual sensitivity of boat travelers is medium.

 

Ÿ         Mo Tat Wan - VSR6 (Refer to Figure 10.4 Photo 16)

 

10.51      A paved footpath along the coastline connects Mo Tat Wan and Sok Kwu Wan.  It locates approximately 1600m east of the center of Sok Kwu Wan Retail/Restaurant area.  It is a small residential area with low-rise buildings along Mo Tat Wan beach.  The area overlooks the entrance of Picnic Bay and the water of East Lamma Channel.  Topography screens the view of Sok Kwu Wan. The visual sensitivity of Mo Tat Wan is medium.

 

Ÿ         Lo So Shing (VSR7)

 

10.52      Lo So Shing is approximately 450m across from the center of Sok Kwu Wan Retail/Restaurant area.  The two areas are separate by Picnic Bay and a fish culture zone.  Lo So Shing comprises a small residential area and cultivation lands.  Most of the cultivation land is abandoned and is grown with weeds.  The visual sensitivity of Lo So Shing is low.

 

Sok Kwu Wan Population

 

10.53      The population of Sok Kwu Wan concentrates along the Sok Kwu Wan Second Street and at the east and west of the existing bridge across the Chung Mei Stream.  The population that will be affected by the Project will be small.

 


Review of Planning and Development Control Framework

 

10.54      Under the approved Lamma Island Outline Zoning Plan (OZP) No. S/I-LI/4, the three proposed pumping stations and the STW fall within the following zonings:

 

 

Land Use Zonings

P1A

“Conservation Area” (“CA”)

P1B

“Residential (Group C)” (“R(C)”)

P2

“Open Space” (“O”)

STW

“Conservation Area” (“CA”)

 

10.55      According to the Notes of OZP, there is statutory provision for development of sewage pumping station under “CA”, “R(C)” and “O” zonings that planning permissions from the Town Planning Board would be required under Section 16 of the Town Planning Ordinance.  However, there is no statutory provision for development of sewage treatment works under “CA” zoning and zoning amendments to the OZP would be necessary.”

 

10.56      The land use zoning for most of the study area is “CA”.  There are some recognised sites of conservation interest located at or near the study area (refer to section 8.3 for descriptions).  The planning intent by Government for the area is to conserve its natural landscape and rural character.

 

Potential Sources of Impacts

 

10.57      The components of the Project that are subject to be the potential sources of impact include:

 

Ÿ         One Sewerage Treatment Works (STW).  Construction of the STW would include excavation, formwork, reinforcement and fixing, concreting, backfilling and slope stabilization. 

Ÿ         Three Pumping stations; each with a 2.5m high site boundary wall.  Construction of the pumping stations each with a deodourizer, standby generator, and control kiosk would include excavation, formwork, reinforcement and fixing, concreting, and backfilling. 

Ÿ         Submarine Outfall.  Marine works in the construction phase includes a steel working platform of size 15m wide by 25m long close to the shore for the horizontal directional drilling system.  Dredging work will be at a location which is approximately 300m from the boundaries of the gazetted Fish Culture Zone.  The length of the outfall is approximately 765m.

Ÿ         Sewer.  The construction of the proposed sewerage works would include breaking up pavement, excavation of trench, installation of pipes and bedding, backfilling, and reinstating road surface.  The total length of the sewer is approximately 1,400m.

 

Landscape Impact Assessment

 

10.58      The landscape impact assessment of the Project is scheduled in Table10.1 and Table 10.2.  The assessment gives the expected landscape impact during the construction and operation phases, before and upon mitigation measures.  The table includes information on the landscape receiver, description of existing landscape condition, sensitivity of receiver, potential source of impact, magnitude of change, landscape impact before mitigation, mitigation measures, and residual impact upon mitigation.  An outline of the relevant impact is described below. 

 

Ÿ         Impact to Sheltered Coastal Area – LCA1

 

10.59      The scheme proposals will result in the loss of vegetation (approximately 445m2) at P1A and P1B locations; the vegetation type is shrubland/grassland which will not be a significant loss.  An exposed rising main sewer will be connected across the existing bridge causing minimal impact.  The underground gravity sewer alignment will result in disturbance to the existing footpath.  In the context that the landscape impact is comparatively small within the site as a whole, the magnitude of impact for both construction and operation phases is small

 

Ÿ         Impact to Sok Kwu Wan Retail / Restaurant Area – LCA2

 

10.60      The scheme proposal will result in the excavation and disturbance to the footpath running along First Street of Sok Kwu Wan Village and side streets for the installation of the underground gravity sewer pipeline connection to Pumping Station P2.  This area is mainly a tourist attraction; during construction, its recreational quality will be disturbed by the construction activities.

 

10.61      The construction of Pumping Station P2 will result in vegetation loss (approximately 310m2) at the base of the disused quarry face.  One tree, Macaranga tanarius, is identified to be transplanted.  The magnitude of impact in construction phase is considered intermediate.  The magnitude of impact in operation phase is considered small.

 

Ÿ         Impact to Exposed Coastline Area – LCA3

 

10.62      The vegetation alongside the footpath from Pumping Station P2 to the STW located within the disused quarry will be disturbed by construction.  Coastal shrubland vegetation will be disturbed by construction of the STW (approximately 1529m2) and the sewage outfall.  The recreational quality along the footpath trail will be disturbed during construction.  The magnitude of change is intermediate in construction phase and is small in operation phase.

 

Ÿ         Impact to Vegetation – LS1

 

10.63      A tree survey has been conducted for the Project.  The survey identifies trees that are in or at the vicinity of the works area and outlines recommendations for them.  The survey identifies 138 no. of tress in which 5 nos. are to be felled, 132 nos. are to be retained, and 1 no. is to be transplanted.  The trees identified to be felled do not have significant amenity value; four of the trees are dead and one tree is within the proposed STW site.

 

10.64      The vegetation that will be disturbed is mainly localised at the P1A, P1B, P2 and STW sites since the pipeline alignment will follow the existing footpath.  The vegetation that will be disturbed is mainly shrubland/grassland type.  The estimated disturbed area is 2283m2 which is 1% of the study area.  In the context of the study area, the possible affected area is considered small, thus, the magnitude of change for both construction and operation phases is small.


Table 10.1                   SUMMARY OF LANDSCAPE IMPACT ASSESSMENT IN CONSTRUCTION PHASE

IDEN-TITY NO.

LANDSCAPE RECEIVER

DESCRIPTION OF EXISTING LANDSCAPE CONDITION

RECEIVER

SEN-SITIVITY

POTENTIAL SOURCE OF IMPACT

MAGNITUDE  OF CHANGE (Construction)

LANDSCAPE IMPACT (Construction) BEFORE MITIGATION

MITIGATION MEASURES

RESIDUAL IMPACT (Construction) UPON MITIGATION

LCA1

Sheltered Coastline Area

A steeply  sloped, vegetated valley with an alluvial plain at its base.  Low-rise residential units (approximately 15 units) scatters in the higher area and some (approximately 10 units) are at the base of the valley.  A concrete bridge connects the east and west side of the valley.

Medium

Disturbance of vegetation (approximately 445m2) from construction of P1A and P1B.  Disturbance of footpath for the sewer.

Small

Slight/

Moderate adverse

Short excavation sections and immediate back filling upon completion of sections.  Protect existing trees and minimise damage to vegetation. 

Slight adverse

LCA2

Sok Kwu Wan Retail / Restaurant Area

The ferry pier and open-air seafood restaurants lining the waterfront First Street.  Low-rise residential buildings lining the Second Street.  A 150 years old Tin Hau Temple is located within the southern section of the area.  A amenity/recreation area with ball courts, a children’s play area, and a disused quarry are located within the northern section of the area.

Medium

Construction activities in First Street; disturbance to footpath.  Construction of P2 at the base of the disused quarry behind the football court. Disturbance of vegetation (approximately 310m2)

Intermediate

Moderate adverse

As above.

 

Slight adverse

LCA3

Exposed Coastline Area

The coastline is in most part rocky and natural.  A paved footpath is inbetween the vegetated cliff and the steep vegetated and rocky hillside.  A refuse transfer collection facility is located at the coastline.

Medium

Disturbance to footpath and coastal vegetation.  STW at the disused quarry; possible slope stabilization works.  Construction of the outfall.  Vegetation disturbance is approximately 1529m2.

Intermediate

Moderate adverse

As above.

 

Slight/

Moderate adverse

LS1

Vegetation

3 broad classification of vegetation:

Woodland (approximately 5.1ha);

Shrubland/grassland (approximately 23.8 ha); Cultivation (approximately 1ha)

 

Low

Disturbance of vegetation

Woodland (insignificant, predicted 5 no. trees to be felled, 1 no. to be transplanted); Shrubland/grassland (approximately  2283m2, 1%); Cultivation 0%

Small

Slight adverse

Protect existing trees and minimise damage to vegetation by close coordination and on-site adjusting alignment of pipeline.  Compensatory planting to affected areas.

Negligible

Note: LCA – Landscape Character Area; LS – Landscape Resource

 

Table 10.2                   SUMMARY OF LANDSCAPE IMPACT ASSESSMENT IN OPERATION PHASE

 

IDEN-TITY NO.

LANDSCAPE RECEIVER

DESCRIPTION OF EXISTING LANDSCAPE CONDITION

RECEIVER

SEN-SITIVITY

POTENTIAL SOURCE OF IMPACT

MAGNITUDE  OF CHANGE (OPERATION)

LANDSCAPE IMPACT (OPERATION) BEFORE MITIGATION

MITIGATION MEASURES

RESIDUAL IMPACT (OPERATION) UPON MITIGATION

LCA1

Sheltered Coastline Area

A steeply sloped, vegetated valley with an alluvial plain at its base.  Low-rise residential units (approximately 15 units) scatters in the higher area and some (approximately 10 units) are at the base of the valley.  A concrete bridge connects the east and west side of the valley.

Medium

Presence of P1A at west side of foot bridge and P1B at the east side (site area 202.5m2 for P1A and 241m2 for P1B; each with a 2.5m high fence wall). 

Small

Slight/

Moderate adverse

Architectural finishes to P1s. 

Negligible

LCA2

Sok Kwu Wan Retail / Restaurant Area

The ferry pier and open-air seafood restaurants lining the waterfront First Street.  Low-rise residential buildings lining the Second Street.  A 150 years old Tin Hau Temple is located within the southern section of the area.  A amenity/recreation area with ball courts, a children’s play area, and a disused quarry are located within the northern section of the area.

Medium

Presence of P2 (site area 310m2) at the base of the disused quarry behind the football court. P2 has a 2.5m high fence wall.

Small

Slight/

Moderate adverse

Architectural finishes to P2.

Negligible

LCA3

Exposed Coastline Area

The coastline is in most part rocky and natural.  A paved footpath is in between the vegetated cliff and the steep vegetated and rocky hillside.  A refuse transfer collection facility is located at the coastline.

Medium

Presence of STW (site area 1529m2, maximum 7m above ground; refer to Figure 10.13 for STW layout.) at the disused quarry.  Reformed slope behind STW.  STW has a 2.5m high fence wall.

Small

Slight/

Moderate adverse

Architectural and soft landscape finishes to STW.  Planting to reformed slope.

Slight adverse

LS1

Vegetation

3 broad classification of vegetation:

Woodland (approximately 5.1ha);

Shrubland/grassland (approximately 23.8 ha); Cultivation (approximately 1ha)

 

Low

-

Negligible

Negligible

None required.

Negligible

Note: LCA – Landscape Character Area; LS – Landscape Resource


Visual Impact Assessment

 

10.65      The visual impact assessment of the Project is scheduled in Table10.3 and 10.4.  The assessment gives the expected visual impact during the construction and operation phases, before and upon mitigation measures.  The table includes information on the visual sensitive receiver, description of existing view, receiver sensitivity, minimum viewing distance, potential source of impact, magnitude of change, visual impact before mitigation, mitigation measures, and residual impact upon mitigation.  An outline of the relevant impact is described below.

 

Ÿ         Impact to Primary Low Rise Residential – VSR1

 

10.66      The proposed sewerage pipeline will be underground through First Street and residential side streets.  The view of the Pumping Station P2 will be limited.  During construction phase, the magnitude of change is considered intermediate.  In the operation phase, the magnitude of change is considered negligible

 

Ÿ         Impact to Secondary Low-Rise Residential – VSR2

 

10.67      The location of Pumping Station P1A and P1B will be visible from residential blocks on the eastern and western side of the existing bridge.  The pipeline alignment will follow the existing footpath and will be underground, other than the section across the bridge.  Due to the small area of the pumping stations, the magnitude of change is small in both construction and operation phases. 

 

Ÿ         Impacts to Restaurants along Coastline – VSR3

 

10.68      The main visual impact to the restaurants along coastline is the close view of the construction activities along First Street.  During construction, the magnitude of change is intermediate.  Since the pipeline will be underground, the magnitude of change in operation is negligible.

 

Ÿ         Impacts to Pedestrian – VSR4

 

10.69      The main disturbance to pedestrian is the breaking up of footpath for laying the pipeline.  The requirement to remove vegetation at the location of Pumping Stations P1A, P1B, P2 and STW will be visible to pedestrian VSR.  However, the area is small and the vegetation type is mainly shrubland/grassland which is not a significant resource.  The gravity sewer pipeline will be mostly underground and will therefore not be visible in operation.  The location of the STW located at the disused quarry will be visible to pedestrian using the coastal footpath to Mo Tat Wan.  The magnitude of change in construction phase is intermediate and is small in operation phase.

 

Ÿ         Impacts to Boat Traveler - VSR5

 

10.70      The major view of the boat travelers is the sea-borne construction traffic and activities at the outfall area.  Construction activities on land will be partially screened by existing coastal vegetation.  Partial view of the STW will be expected.  Magnitude of change in construction phase is considered intermediate.  Magnitude of change in operation phase is considered small.

 

Ÿ         Impacts to Mo Tat Wan – VSR6

 

10.71      The major view to Mo Tat Wan VSR is the sea-borne construction traffic and activities at the outfall area.  The construction activities at Sok Kwu Wan will be screened by topography.  Magnitude of change in construction phase is considered intermediate.  Magnitude of change in operation phase is considered negligible.

 

Ÿ         Impacts to Lo So Shing – VSR7

 

10.72      The view of the pumping stations and STW from Lo So Shing will be screened by topography.  The change of view in construction will be the increased sea-borne construction traffic.  Magnitude of change in construction is considered small.  Magnitude of change in operation is negligible.

 

 


Table 10.3                   SUMMARY OF VISUAL IMPACT ASSESSMENT IN CONSTRUCTION PHASE

 

IDEN-TITY NO:

VISUAL SENSITIVE RECEIVER

DESCRIPTION OF EXISTING VIEW

RECEIVER SENSI-TIVITY

MIN. VIEWING DISTANCE (M)

POTENTIAL SOURCE OF VISUAL IMPACT

MAGNITUDE  OF CHANGE (Construction)

VISUAL IMPACT (Construction) BEFORE MITIGATION

MITIGATION MEASURES

RESIDUAL IMPACT (Construction) UPON MITIGATION

VSR1

Primary Low Rise Residential/Retail

Views are open towards Picnic Bay including the fish culture zones, Lamma Quarry, First Street and Second Street.  The views to the south are the steep woodland hillside.

Medium

Adjacent

Construction of sewer pipeline at First Street and side streets.

Intermediate

Moderate adverse

Use of hoarding to screen construction activities and trenches.  Short excavation and immediate backfilling of sections upon completion of works.

Slight/Moderate adverse

VSR2

Secondary Low Rise Residential

Views are open to the surrounding hillsides and over Picnic Bay and Lamma Quarry.

 

Medium

Adjacent

Construction activities of P1A, P1B and sewer. 

Small

 

Slight/

Moderate adverse

As above.

Slight adverse

VSR3

Restaurants alongside Coastal Footpath

Views are open to Picnic Bay including the fish culture zones and towards Lamma Quarry.

 

Medium

Adjacent

Construction of sewer.

Intermediate

Moderate adverse

As above.

Slight/Moderate adverse

VSR4

Pedestrain

Pedestrians along the paved footpath will experience views of the surrounding vegetated hillsides, Picnic Bay including the fish culture zones, the Lamma Quarry, Hong Kong Island across the ocean.  At some sections of the footpath, the views will be enclosed with vegetation on bothsides.

 

Medium

Adjacent

All associated construction activities.

Intermediate

Moderate adverse

As above.

Slight/Moderate adverse

VSR5

Boat Travelers

Views include the fish culture zones and waterfront restaurants in the foreground with vegetated hillsides and rocky coastline in the background.

 

Medium

200m

Construction activities of STW located at the base of the disused quarry and outfall, including sea-borne traffic.

Intermediate

Moderate adverse

Minimise damage to vegetation at the coastal cliff of the STW site.

Moderate adverse

VSR6

Mo Tat Wan

Views include the entrance to Picnic Bay, surrounding vegetated hillsides, Lamma Quarry, Hong Kong Island across the East Lamma Channel.

Medium

250m

Sea-borne construction traffic and activities at outfall area.

Intermediate

Moderate adverse

If night lighting is required for the marine fleets near Mo Tat Wan, the light source should be directed away from the residential units.

Moderate adverse

VSR7

Lo So Shing

Views include surrounding vegetated hillsides, Picnic Bay including the fish culture zones and Lamma Quarry and the waterfront restaurants.

Slight

450m

Sea-borne construction traffic

Small

Slight adverse

None identified.

Slight adverse

 

VSR = Visually Sensitive Receiver

 


Table 10.4                   SUMMARY OF VISUAL IMPACT ASSESSMENT IN OPERATION PHASE

 

IDEN-TITY NO:

VISUAL SENSITIVE RECEIVER

DESCRIPTION OF EXISTING VIEW

RECEIVER  SENSI-TIVITY

MIN. VIEWING DIS-

TANCE

(M)

POTENTIAL SOURCE OF VISUAL IMPACT

MAGNITUDE  OF CHANGE (Operation)

VISUAL IMPACT (Operation) BEFORE MITIGATION

MITIGATION MEASURES

RESIDUAL IMPACT (Operation) UPON MITIGATION

VSR1

Primary Low Rise Residential/Retail

Views are open towards Picnic Bay including the fish culture zones, Lamma Quarry, First Street and Second Street.  The views to the south are the steep woodland hillside.

Medium

Adjacent

None.  Pipeline is underground.

Negligible

Negligible

None required.

Negligible

 

VSR2

Secondary Low Rise Residential

Views are open to the surrounding hillsides and over Picnic Bay and Lamma Quarry.

 

Medium

Adjacent

View of P1A at west side of footbridge and P1B at east of footbridge (P1A site area 202.5m2, P1B site area 241m2, each with a 2.5m high fence wall).  Short portion of exposed pipeline across footbridge (approximately 20m).

Small

Slight/

Moderate adverse

Architectural finishes to pumping stations.  Appropriate paint finishes to exposed pipeline.

Negligible

VSR3

Restaurants alongside Coastal Footpath

Views are open to Picnic Bay including the fish culture zones and towards Lamma Quarry.

 

Medium

Adjacent

None.  Pipeline is underground.

Negligible

Negligible

None required.

Negligible

VSR4

Pedestrian

Pedestrians along the paved footpath will experience views of the surrounding vegetated hillsides, Picnic Bay including the fish culture zones, the Lamma Quarry, Hong Kong Island across the East Lamma Channel.  At some sections of the footpath, the views will be enclosed with vegetation on coastal cliff.

 

Medium

Adjacent

Pumping stations and STW.  Short portion of exposed pipeline across footbridge (approximately 20m).  Reformed slope behind STW.

Small

Slight/

Moderate adverse

Architectural and soft landscape finishes to pumping stations and STW.  Appropriate paint finishes to exposed pipeline.  Planting to reformed slope.

Slight adverse

VSR5

Boat Travelers

Views include the fish culture zones and waterfront restaurants in the foreground with vegetated hillsides and rocky coastline in the background.

Medium

200m

STW at disused quarry partially screened by existing vegetation at coastal cliff.  Reformed slope behind STW.

Small

Slight/

Moderate adverse

Architectural and soft landscape finishes to STW.  Planting to reformed slope.

Slight adverse

VSR6

Mo Tat Wan

Views include the entrance to Picnic Bay, surrounding vegetated hillsides, Lamma Quarry, Hong Kong Island across the East Lamma Island.

Medium

250m

None (outfall is submarine)

Negligible

Negligible

None required.

Negligible

VSR7

Lo So Shing

Views include surrounding vegetated hillsides, Picnic Bay including the fish culture zones and Lamma Quarry and the waterfront restaurants.

Medium

450m

None.

Negligible

Negligible

None required.

Negligible

 

VSR = Visually Sensitive Receiver

 


Mitigation Measures

 

10.73      Mitigation of landscape and visual impacts will be achieved by appropriate construction practice, design and surface treatment of the built elements and appropriate soft landscape treatment within available areas of the Project.  These mitigation measures are described below.  The implementation schedule of mitigation proposals is outlined in Table 10.5.

 

Landscape Objectives

 

The guiding objectives for landscape design and mitigation treatment include the following:

Ÿ         to establish a coherent language within the overall landscape character and built elements.

Ÿ         to visually screen the built elements.

Ÿ         to establish low maintenance planting areas through species selection.

 

Mitigation Measures - Construction Phase

 

10.74      The duration of construction phase is approximately 30 months.  Landscape and visual mitigation measures in the construction phase include (refer to Figures 10.6, 10.10):

 

Ÿ         screening of site construction works by use of hoarding that is appropriate to its site context;

Ÿ         retaining existing trees and minimising damage to vegetation where possible by close co-ordination and on site alignment adjusted of rising main and gravity sewer pipelines.  Tree protective measures should be implemented to ensure trees identified as to be retained are satisfactorily protected during the construction phase;

Ÿ         careful and efficient transplanting of affected trees (1 no.) to temporary or final transplant locations (the proposed tree to be transplanted is a semi-mature Macaranga tanarius and is located at the proposed pumping station P2 location); 

Ÿ         short excavation and immediate backfilling of sections upon completion of works to reduce active site area;

Ÿ         conservation of top-soil for reuse; and

Ÿ         if night lighting is required for the marine fleets near Mo Tat Wan, the light source should be directed away from the residential units.

 

Mitigation Measures - Operational Phase

 

10.75      The recommended scheme proposes the construction of Pumping Stations P1A, P1B, P2, STW and installation of gravity and rising main sewer pipelines connected to a submarine outfall.  These ancillary buildings and facilities will cause a number of localised landscape and visual impacts.  Mitigation measures have been formulated to alleviate these impacts.  (refer to Figures 10.8 and 10.12):

 

Ÿ         planting to reformed slope areas in-keeping with the surrounding landscape character. 

Ÿ         appropriate finishes to reinstated areas of footpath in-keeping with existing finishes;

Ÿ         architectural finishes to proposed structures that are sympathetic to the surrounding landscape (refer to Figures 10.13, 10.14.1, 10.14.2);

Ÿ         soft landscape finishes to the proposed structures to reduce visual prominence; and

Ÿ         appropriate paint finishes to sections of exposed pipeline to reduce visual prominence.Summary of Mitigation Measrues

 

Table 10.5 Implementation Schedule of Mitigation Measures

 

Mitigation Measure

Funding Agency

Implementat-ion Agency

Management Agency

Maintenance Agency

Construction Phase

Screening of site construction works by use of hoarding that is appropriate to its site context.

DSD

DSD’s Contractor

DSD’s Consultant

DSD’s Contractor

Retaining existing trees and minimizing damage to vegetation where possible by close coordination and on site alignment adjusted of rising main and gravity sewer pipelines.  Tree protective measures should be implemented to ensure trees identified as to be retained are satisfactorily protected.

DSD

DSD’s Contractor

DSD’s Consultant

DSD’s Contractor

Careful and efficient transplanting of affected trees (1 no.) to temporary or final transplant location.

DSD

DSD’s Contractor

DSD’s Consultant

DSD’s Contractor

Short excavation and immediate backfilling of sections upon completion of works to reduce active site area.

DSD

DSD’s Contractor

DSD’s Consultant

DSD’s Contractor

Conservation of top-soil for reuse.

DSD

DSD’s Contractor

DSD’s Consultant

DSD’s Contractor

If night lighting is required for the marine fleets near Mo Tat Wan, the light source should be directed away from residential units.

DSD

DSD’s Contractor

DSD’s Consultant

DSD’s Contractor

Operation Phase

Planting to reformed slope areas in-keeping with the surrounding landscape character.

DSD

DSD’s Consultant & Contractor

DSD

DSD

Appropriate finishes to reinstated areas of footpath in-keeping with existing finishes.

DSD

DSD’s Consultant & Contractor

DSD

DSD

Architectural finishes to proposed structures that are sympathetic to the surrounding landscape.

DSD

DSD’s Consultant & Contractor

DSD

DSD

Soft landscape finishes to the proposed structures to reduce visual prominence.

DSD

DSD’s Consultant & Contractor

DSD

DSD

Appropriate paint finishes to sections of exposed pipeline to reduce visual prominence.

DSD

DSD’s Consultant & Contractor

DSD

DSD

 

Photomontage

 

10.76      The photomontage (Figure 10.15a and 10.15b) shows the viewpoint of a boat traveler viewing towards the proposed STW site.  It shows the approximate scale of the proposed STW and the vegetated hill in the backdrop.  As traveling by boat is the main mode of transport to Sok Kwu Wan, this viewpoint represents the major view of the visual receivers.

 

10.77      The colour scheme of the STW is proposed to be earth tones that are in-keeping to the tone of the quarry in the backdrop.  At Day 1 of operation, the newly planted trees along the footpath partially screen the view of the STW.

 

10.78      At Year 10 of operation, the trees will have grown in size to screen most of the STW.