This Section presents the Landscape and
Visual Impact Assessment (LVIA) for the Project. The assessment includes:
·
A
review of the relevant environmental legislation and guidelines;
·
A
review of the relevant planning and development control framework;
·
A description
of the Project, including a broad description of the alternative options
considered;
·
A
description of the assessment methodology including the limits of the Study
Areas;
·
A
baseline study which provides a comprehensive description of the baseline
landscape and visual characters and a rating for their sensitivity; and
·
An
impact assessment, including identification of potential landscape and visual
impacts, prediction of their magnitude and potential significance,
recommendation of appropriate mitigation measures and associated implementation
programmes. The assessment also
discussed the potential impacts before and after the implementation of the
mitigation measures.
Colour photographs showing baseline conditions and
photomontages and illustrative materials supporting conclusions are provided
and the locations of all the viewpoints are clearly mapped. Photomontages at representative viewpoints
provide a comparison between the existing views, proposals on day 1 after
completion without mitigation, proposals on day 1 after mitigation and
proposals on year 10 after mitigation.
4.2
Environmental
Legislation & Guidelines
The following legislation, standards and guidelines
are applicable to the assessment of landscape and visual impacts associated
with the Project.
·
Environmental Impact Assessment Ordinance (Cap.499, S.16) and the associated Technical Memorandum on EIA Process
(EIAO-TM), particularly:
o
Annex
10 - Criteria for Evaluating Visual and Landscape Impact, and Impact on Sites
of Cultural Heritage;
o
Annex
18 - Guidelines for Landscape and Visual Impact Assessment;
·
EIAO Guidance Note No. 8/2010 - Preparation of Landscape and Visual
Impact Assessment under the Environmental Impact Assessment Ordinance;
·
ETWB-TC(W) No. 3/2006 - Tree Preservation;
·
ETWB-TC(W) No. 29/2004 - Registration of Old and Valuable Trees,
and Guidelines for their Preservation;
·
ETWB-TC(W) No. 10/2005 - Planting on Footbridges and Flyovers;
·
Land Administration Office (LAO), Lands
Department Practice Note No. 7/2007 - Tree Preservation and Tree Removal Application for
Building Development in Private Projects;
·
WBTC No. 7/2002 - Tree Planting in Public Works;
·
·
Study
on Landscape Value Mapping of
The study has also been conducted in accordance with
the requirements of Section 3.4.2 of EIA Study Brief No. ESB-205/2009,
issued under the EIAO.
4.3
Planning and
Development Control Framework
The Site is located in an urban area in
Central and covered by the “Draft Sai Ying Pun
& Sheung Wan” Outline Zoning Plan No. S/H3/24. It has been zoned
as “OU” annotated “Historical Site Preserved for Cultural, Recreational and
Commercial Uses”. According to the Notes
of the OZP, the planning intention of the zone is intended to preserve, restore
and convert the historic site into a heritage tourism attraction that would
provide a wide range of cultural, recreational and commercial facilities for
the enjoyment of local residents and tourists.
The current proposed conservation and revitalisation of
In addition the Site is subject to building height
restrictions with maximum building heights of 60mPD and 70mPD imposed on the
lower and upper levels of the Site for existing buildings and 80mPD for any new
buildings on the upper level. The two
existing courtyards within the Site are to be preserved. The current proposed built structures of the
4.4
Impact Assessment
Methodology
The landscape impact assessment (LIA) considers the potential
impacts of the Project on the existing landscape within 500m of the Site (the
Study Area). In accordance with Annex 18 of the EIAO-TM, the LIA covers the following tasks:
1.
Identification of the baseline landscape
resources (LRs) and landscape characters areas (LCAs) within the Study Area
This was achieved through site visits as well as a
desk-top study of topographical maps, information databases and
photographs. A tree specialist was
appointed to undertake a tree survey to evaluate the trees within the Site with
respect to species characteristics, tree structure, to assess the site
conditions for each tree and provide information regarding arboricultural
concerns and recommendations for treatment of each tree, if required. Where relevant, information from the tree
study has been extracted to supplement information regarding the baseline
conditions, impact assessment and mitigation measures.
2.
Assessment of the sensitivity of LRs/LCAs
This is influenced by a number of factors including whether
the LR/LCA is common or rare, whether it is considered to be of local,
regional, national or global importance, whether there are any statutory or
regulatory limitations/requirements relating to the resource, the quality of
the LR/LCA, the maturity of the LR, and the ability of the LR/LCA to
accommodate change.
The sensitivity of each LR and LCA was classified as
follows:
·
High: Important
landscape resource or landscape of particularly distinctive character or high
importance, sensitive to relatively small changes;
·
Medium: Landscape
resource or landscape of moderately valued landscape character, reasonably
tolerant to change; and
·
Low: Landscape
resource or landscape, the nature of which is largely tolerant to change.
3.
Identification of potential sources of
landscape impacts
These are the various elements of the construction
and operation works that have the potential to cause landscape impacts.
4.
Identification of the magnitude of
landscape impacts
The magnitude of the impact depends on a number of
factors including the physical extent of the impact, the landscape context of
the impact, the compatibility of the Project with the surrounding landscape;
and the time-scale of the impact, ie whether it is
temporary (short, medium or long-term), permanent but potentially reversible,
or permanent and irreversible. Landscape
impacts have been quantified wherever possible. The magnitude of landscape
impacts is classified as follows:
·
Large:
The landscape resource
or landscape will experience a major change;
·
Intermediate: The landscape resource or landscape will experience a moderate change;
·
Small:
The landscape
resource or landscape will experience slight or barely perceptible changes; and
·
Negligible: The landscape resource or landscape will experience no discernible
change.
5.
Identification of potential landscape
mitigation measures
These may take the form of adopting alternative
designs or revisions to the architectural design to prevent and/or minimise adverse
impacts; remedial measures such as colour and textural treatment of building
features; and compensatory measures such as the implementation of landscape
design measures (eg tree planting) to compensate for
unavoidable adverse impacts and to attempt to generate potentially beneficial
long-term impacts. A table of proposed
mitigation measures is provided with the suggested agencies responsible for
their funding, implementation and management/ maintenance identified.
6.
Prediction of the significance of
landscape impacts before and after the implementation of the mitigation
measures
By synthesising the magnitude of the various impacts
and the sensitivity of the various landscape resources the potential impacts
will be categorised in a logical and consistent fashion. Table 4.1 shows the rationale for dividing the degree
of significance into four thresholds, namely insignificant, slight, moderate,
and significant, depending on the combination of a low-medium-high degree of sensitivity
of LR/LCA with a negligible-small-intermediate-large magnitude of impact.
Table
4.1 Impact Significance of Landscape or
Visual Impact
|
|
|
Receptor Sensitivity (LR/ LCA/ Visual Sensitive
Receptor) |
||
|
Magnitude of Impact |
|
Low |
Medium |
High |
|
Large |
Slight/Moderate * |
Moderate/ Significant* |
Significant |
|
|
Intermediate |
Slight/Moderate * |
Moderate |
Moderate/ Significant * |
|
|
Small |
Slight |
Slight/ Moderate |
Moderate |
|
|
Negligible |
Insignificant |
Insignificant |
Insignificant |
|
* In those instances where the lower level
of impact is predicted, this is justified in the description of the impact
The significant thresholds are defined as follows:
·
Significant: Adverse/beneficial impact which will cause
significant deterioration or improvement in existing landscape quality.
·
Moderate: Adverse/beneficial impact which will cause a
noticeable deterioration or improvement in existing landscape quality.
·
Slight: Adverse/beneficial impact which will cause a barely
perceptible deterioration or improvement in existing landscape quality.
·
Insignificant: The impact will cause no discernible
change in the existing landscape quality.
7.
Prediction of Acceptability of Impacts
An overall assessment of the acceptability, or
otherwise, of the impacts will be carried out according to the five criteria
set out in Annex 10 of the EIAO-TM namely beneficial, acceptable,
acceptable with mitigation measures, unacceptable and undetermined.
The visual impact assessment (VIA)
analyses the potential visual impacts of the Project with respect to the
existing views and the visual amenity of the representative Visually Sensitive
Receivers (VSR) identified within a visual envelope.
In accordance with Annex 18 of the EIAO-TM
the VIA covers the following tasks:
1.
Identification
and plotting of the Visual Envelope
This is achieved by GIS visual envelope analysis, as well as
site visits, desktop study of topographic maps and photographs and to determine
visibility of the Project from various locations. The visual envelope is largely
contained by the high rise buildings in the built environment of the Site
location. Only a small number of high
rise buildings at a distance greater than 500m from the Site would have a view
of it and these VSRs were considered to be too small
in number and have a large number of alternative views such they would not be
significantly impacted by the Project.
2.
Identification
of VSRs and Vantage Points (VPs) within the Visual
Envelope
VSRs are people who would reside, play, work or travel in
or through the Visual Envelope. There
are many VSRs within a visual envelope and those of
similar sensitivity can be grouped. VSR’s view points were studied through desktop analysis and
on-site inspection, and a number of locations selected from which to analyse
the visual impact of the Project. These
locations are considered to be indicative of the range of views from accessible
locations within the visual envelope and represent the full range of VSR
groups. VSRs
can be partially categorised by type, as classified in bullet 3.
Through further site visits and desktop analysis,
five VSR points were also selected as Vantage Points (VPs), from which to
compile photomontages to illustrate visual impacts at these points. The five VPs, VPa
to VPe, were chosen to represent worst case scenarios for VSRs
within the visual envelope, mainly due to their proximity to and degree of
visibility of the Site.
3.
Assessment
of the sensitivity of the VSRs
Factors considered include:
·
Type
of VSR: This is
classified according to the visual impact imposed by the Project and is
influenced by such things as whether a person is at home, at work, at play, or
travelling.
o
Those
who view the impact from their homes are considered to be highly sensitive as
the character of view from their home will have a substantial effect on their perception
of quality and acceptability of their home environment and their general
quality of life. These are ‘Residential’
VSRs (H).
o
Those
who view the impact from their workplace are considered to be relatively less
sensitive as the character of view will have a less important effect on their
perception of quality of life. These are
‘Occupational’ VSRs (O).
o
Those
who view the impact while engaging in outdoor recreational activities may
display varying sensitivity depending on the type of activity. These are ‘Recreational’ VSRs
(R).
o
Those
who view the impact while travelling in public/private vehicles or on foot will
display varying sensitivity depending on the speed, nature and frequency of
travel. These are ‘Travelling’ VSRs (T).
·
Other factors: As required by EIAO
Guidance Note No. 8/2002, other factors include 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 sensitivity of the VSRs
is classified as follows:
·
High: The VSR is
highly sensitive to any change in their viewing experience.
·
Medium: The VSR is
moderately sensitive to any change in their viewing experience.
·
Low: The VSR is only
slightly sensitive to any change in their viewing experience.
4.
Assessment
of the relative numbers of VSRs
This is expressed in terms of whether there are very
few, few, many or very many VSRs
in any one group of VSRs represented by the VSR point
in question.
5.
Assessment
of the potential sources of visual impacts
These are the various elements of the construction
works and operation procedures that have the potential to cause visual impacts.
6.
Assessment
of the potential magnitude of visual impacts
The magnitude of visual impacts depends on a number
of factors including the compatibility of the Project with the surrounding
landscape; duration of impacts; scale of development; reversibility of the impact;
distance of the source of impact from the viewer; and degree of visibility of
the impact and the degree that the impact dominates the field of vision of the
viewer.
The magnitude of visual impact is classified as
follows:
·
Large: The VSRs will experience a
major change in the character of their existing views.
·
Intermediate: The VSRs will experience a
moderate change in the character of their existing views.
·
Small: The VSRs will experience a
small change in the character of their existing views.
·
Negligible: The VSRs will experience
no discernible change in the character of their existing views.
7.
Assessment
of the potential visual mitigation measures
These may take the form of adopting alternative
designs or revisions to the basic engineering and architectural design to
prevent and/ or minimise adverse impacts, remedial measures such as colour and
textural treatment of building features; compensatory measures such as tree
planting to screening roads and elevated viaduct structures. A table of proposed mitigation measures is
provided with the suggested agencies responsible for their funding,
implementation and management/ maintenance identified.
8.
Prediction
of the significance of visual impacts before and after the implementation of
mitigation measures
By synthesising the magnitude of the
various impacts and the sensitivity of the various visual impacts, sensitivity
of VSRs, and the number of affected VSRs, the degree of significance of the impacts will be
categorised in a logical, well-reasoned and consistent manner. Table 4.1 shows the rationale for dividing the degree
of significance into four thresholds, namely, Insignificant, Slight, Moderate
and Significant, depending on the combination of a negligible-small-intermediate-large
magnitude of impact and a low-medium-high degree of sensitivity of VSRs. Consideration
is also given to the relative numbers of affected VSRs
in predicting the final impact significance – exceptionally low or high numbers
of VSRs may change the result that might otherwise be
concluded from Table
4.1.
The significant thresholds are defined as
follows:
·
Significant: Adverse/beneficial impact where the Project will cause
significant deterioration or improvement in existing visual quality.
·
Moderate: Adverse/beneficial impact where the Project will
cause a noticeable deterioration or improvement in existing visual quality.
·
Slight: Adverse/beneficial impact where the Project will
cause a barely perceptible deterioration or improvement in existing visual
quality.
·
Insignificant: The impact will cause no discernible
change in the existing visual quality.
9.
Prediction
of Acceptability of Impacts.
An overall assessment of the acceptability, or
otherwise, of the impacts will be carried out according to the five criteria
set out in Annex 10 of the EIAO-TM, namely Beneficial, Acceptable,
Acceptable with Mitigation Measures, Unacceptable and Undetermined.
In addition, colour photographs showing baseline
conditions, photomontages and illustrative materials supporting conclusions are
provided and the locations of all key VPs are clearly mapped. Photomontages at the representative worst
case scenario locations will be prepared to provide a comparison between
existing views, proposals on Day 1 after completion without mitigation
measures, on Day 1 complete with mitigation measures, and in Year 10 after
mitigation measures are implemented.
Section
2 gives a full
description of the Project, including the Project Site (Site) description and
history, need for the Project, consideration of alternative options including
design options for both new structures and a description of the Project with
the rationale behind the selected options, including the general Project
philosophy and concept. Key information
is summarised here.
The Site is located in Central (see Figure 2.1). It
is collectively named the Central Police Station (CPS) and includes three
Declared Monuments designated under the Antiquities
and Monuments Ordinance in 1995 (Central Police Station, Former Central Magistracy
and Victoria Prison Compound) with a number of with Victorian/ Edwardian style
buildings and a surrounding wall.
The design and planning of the Project, has all been
undertaken with the view to providing a contemporary art hub at the
A number of different design options have been
identified and examined to best meet all the requirements, including only
utilising the existing buildings for adaptive use and alternatively building
new structures. Simply using existing
buildings was ruled out for reasons including inadequate size for the proposed
uses, the need for substantial intervention (conflicting with the prime aim of
retaining, conserving and adapting the interiors of the heritage buildings for
suitable reuse) and structural constraints amongst others. As a result the construction of limited new
buildings is proposed.
A Conservation Management Plan ([1])
(CMP) for the CPS was
prepared in 2008 and concluded that there were only two potential sites where
new buildings could be inserted. The open
spaces were ruled out as being too significant in terms of cultural heritage to
build on and the sites were the west side of the Prison Yard where the General
Office is located and the east side of the Prison Yard (see Figure 2.2).
Two design schemes have been identified for the new
buildings; Scheme A with one new building, and Scheme B with two new
buildings. Their merits and shortcomings
are fully described in Section 2 and
key points summarised here. In terms of
visual impact, Scheme A would have a smaller impact than Scheme B, being
smaller. From the landscape point of
view, the footprint identified for the construction of new buildings is
currently occupied by buildings and structures and will not encroached into the
open spaces such that overall there will be no net loss of open space under
either scheme. In terms of potential glare
interference, the extent of impact will depend on the mass of the building as
well as the façade material to be chosen and while Scheme B will involve the
erection of one more building, the design intention of using non-reflective
material for the façade will help to minimise potential glare interference (see
Section 4.7.4 ‘Glare Impact’).
Other factors of both schemes, apart from landscape,
visual and glare impacts, have to be taken into consideration however, and
balancing the demand for the cultural space needed, the level of intervention
within the existing historic buildings, integration with other buildings at the
upper courtyard, engineering constraints and the potential environmental
impacts while achieving the vision of the Project, the implementation of Scheme
B is considered preferable.
The design philosophy of Scheme B (including the
discussion of refining the massing, configuration and façade treatment to
minimise heritage and visual impact) is further elaborated in Section 2.6 but it is important to note
that the use of a modern approach over a historical approach has been
recommended for two key reasons.
Firstly, it is a well-established concept in conservation that new
interventions, whether internal alterations in an historical building or whole
new buildings on an historical site, should be “of their time”. This is because all generations of people
have expressed their culture through their buildings, (amongst other things),
and to copy a style of the past would be to devalue it, and indeed the culture
of today. By constructing new buildings
that speak of today, another chapter in the biography of the site is
added. This then can be viewed by later
generations and understood within the context of the site and its history.
The second reason a modern approach is preferable to
a historical one relates to the building uses.
The form and appearance of buildings are derived from the functions they
perform and their use. The historical
buildings on this site were designed to accommodate people at work (the Police
HQ); people attending formal meetings (the Magistracy); and people in
confinement (the Victoria Prison). In
most cases, the rooms were relatively small, and defined by load bearing
walls. The uses for which the new
buildings are intended all require large, open spaces, with high ceilings, and
much larger rooms than the largest of the rooms in any of the historic
buildings. They also require heavy floor
loadings, which could only be achieved in the historic buildings by making major
interventions in them, which in turn would threaten their cultural
significance. Thus the existing
buildings cannot accommodate the new uses, as identified earlier. To build new buildings with large, open-plan
historical design is possible (there are models for such buildings: for example,
churches, market hall), but these forms of building require more ground area
than is available at the CPS site unless one was to build on the Parade Ground
or Prison Yard. It has already been
established that such proposals would be inappropriate having regard to the
cultural significance of the site. Thus
any new building in the site cannot be made to look like an historical one
given their intended uses.
The chosen Scheme B requires two new
buildings within the Site, namely:
·
The
“Old Bailey Wing”, located at the south west portion of the Site, between the
preserved F hall and Ablution block; and
·
The
“Arbuthnot Wing”, located at the south east portion of the Site between the
preserved E hall and D hall.
The proposed layout plan of the Site is
shown in Figure 2.11 and
cross-sectional plans showing the two new building areas are presented in Figures 2.22 to 2.24. Attributes of the new building areas are
presented in Table 4.2
Table 4.2 Attributes
of New Construction within the Site
|
Facilities |
Nominal
Dimensions L-Length;
W-Width |
Highest mPD |
|
Old Bailey wing |
L-30.4 m W-27 m |
+80 mPD |
|
Arbuthnot wing |
L-27.3 m, W-19 m |
+80 mPD |
|
Footbridge |
L-32.8 m, W-3.7 m |
+45.2 mPD |
A new means of
access to the
Some
other minor works will also be undertaken outside the existing CPS boundary
wall, such as the provision of a narrow pavement on the
4.6.1
General Topography of the Site
The Site is located on a steep slope facing
north-north-east, with buildings on three levels; a lower level (+42 to 46mPD),
middle level (+50mPD) and higher level (+50 to 55mPD). Victoria Prison Compound and the former
Central Magistracy are both on the higher level and Central Police Station is
on the lower level.
LRs found within the Study Area are described below
along with their sensitivity, and illustrated in Figure 4.1. A photorecord of
the various landscape resources are shown in Figure 4.2. Details of all trees found within the Site
are provided in Section 4.6.4.
LR1 –
LR2 – Commercial/
Residential/
LR3
– Buildings within Declared Monument: Refers to the former Victoria Prison compound
buildings (Superintendent’s House; A, B, C, E, F Halls; D Hall east and west
wings; the Laundry; Bauhinia House; Walls & Revetments), the former Central
Magistracy, the Central Police Station buildings (Police Headquarters Block;
Armoury; Barrack Block; Married Inspectors’ Quarters; Deputy Superintendent’s
House; Garage; Single Inspectors’ Quarters; Married Sergeants’ Quarters;
Ablutions Block) and the external brick wall within the
Site. Buildings are principally between
two to four storeys high. This LR has
high cultural value and being predominantly a built environment has reasonable
tolerance to change. It has medium
sensitivity.
LR4 – Open Space within
LR5 –
LR6 – Hong Kong Zoological
& Botanical Garden:
Refers to the
LR7 – Vegetated Slope: Refers to a medium sized non-fragmented
area around the government buildings in the south east of the Study Area and
some small patches near the hillside on the south of the Study area, all
planted with trees/shrubs and mainly on sloping terrain. The dominant species in this LR is the exotic
Archontophoenix alexandrae
of approximately 3.5m average height and in fair health, particularly
around Government House, as well as the exotic Delonix
regia, and native Ficus
microcarpa and Chrysalidocarpus
lutescens. This
LR is important in contributing to the rare green environment of the built up
Study Area. It is a man-made and reasonably
mature resource and is relatively intolerant to change. It has medium sensitivity.
LR8 – Natural
LR9 –
4.6.3
Landscape and Visual Character Areas
Landscape and Visual Character Areas (LCAs) found within the Study Area are described below along
with their sensitivity, and illustrated in Figure 4.3. A photorecord of
the various landscape character areas is shown in Figure 4.4
LCA1 – Historical Landscape: Refers to former Police Married Quarters
on
LCA2 –Park Landscape: Refers to the
LCA3 – Medium/High-rise
Commercial Urban Landscape:
Refers to landscape on predominantly flat and reclaimed land, with medium and
high-rise commercial and retail buildings; principally malls with prestigious
commercial/retail outlets, offices above and connected by pedestrian
bridges. The architecture is modern,
road and streets largely on an orthogonal grid and there is limited open space
and amenity planting. There is a
predominance of man-made features and artificial colours, a distinct sense of
verticality, a high sense of enclosure and busy, vibrant street activity. This LCA is a major commercial district and a
high profile area of the HKSAR. Although
it is dominated by man-made structures, many of them have high architectural
value and it has only average ability to accommodate change. This LR and has medium sensitivity.
LCA4 – Residential/
Commercial Urban Landscape:
This is the largest landscape character within the Study Area and refers to
built up area with primarily residential buildings and limited community and
open space uses. There is also some
commercial and retail use of the buildings within this landscape. This LCA is able to accommodate change and
has low sensitivity.
LCA5 – Central Civic
Administration Landscape:
Refers to landscape including Government House, some Central Government Offices
and their surrounding landscape including some planted areas. Although this LCA is predominantly man-made,
some buildings are of historical value to
LCA6 – Natural
LCA7 – Major Transport
Corridor: This landscape
is made up of the Connaught Road Central highway and junctions near IFC1. The
resource is considered to be highly tolerant to change and its sensitivity is
low.
4.6.4
Trees within the Project Site
The tree
survey undertaken indentified eleven trees within the Site, using the
government's definition of a tree as a woody plant with a trunk diameter of at
least 95 mm at 1.3 m height. None of the
trees can be gauged as being in ‘excellent’ health and only two trees, namely
the large T5 (Mangifera indica)
in the Parade Ground, and the relatively small wall tree T10 (Ficus microcarpa)
between the Police and Prison sites, have performed sufficiently well to
deserve the good rating. The status of
the trees is detailed below and their health and approximate dimensions are
summarized in Table
4.3 along with the proposed treatment for each tree. Figure 4.5 shows the
locations of the eleven trees, as well as detailing their proposed treatment as
outlined in Section 4.7.3 and
provides a photorecord of the trees.
T1 – Bombax ceiba
T1 was a medium-sized Bombax
ceiba, around
25 years old, that measured 15 m tall and 4 m crown diameter before it
was destroyed by Typhoon Fengshen on 25 June
2008. The gale force wind associated
with typhoon signal number 8 snapped the trunk and completely removed its
crown. Before the typhoon, the crown of
T1 overlapped and intertwined with that of its notably larger neighbour
T2. It is possible that T1 was brought
down as collateral damage due to the collapse of the much larger and heavier
T2. For a 15 m tall tree, the trunk
diameter of 22 cm was on the low side and branch development was less than
optimal, indicating that the tree’s performance was of average or fair
calibre. Only the lower segment of the
trunk without any foliage was left of the tree after the typhoon though it is
likely that the root system was able to remain more or less intact. Shortly after the typhoon, the top of the
broken trunk was sawn to form a horizontal flat surface in an attempt to trim
the breakage wound, leaving a trunk segment of 3.5 m tall. Following this, slender sprouts with new
leaves developed from the edge of the wound to rebuild a tiny and unnatural
crown. Measuring 1.9 m wide and with
only a small amount of leaves, the reconstituted crown serves to resume a minimum
amount of plant food production by photosynthesis to sustain the essential
physiological functions of the emaciated tree.
The wind force that caused the trunk snapping had created cracks that
extend downwards from the wound.
Shortly after the typhoon attack, a small tree pit
with concrete rim measuring 150 cm by 81 cm was installed for T1, where
previously its critical root zone had been completely sealed by concrete
paving. With the east side of the tree site
bordered by a retaining wall adjacent to the access road and the north side
adjacent to a building the root extension of T1 is permanently curtailed on two
sides. Its roots could only spread
towards to the south and west in the compacted and sealed soil lying beneath
the continuous concrete paving and the root system of T1 cannot be expected to
develop normally.
The installation of an air conditioner resting on a
concrete plinth next to T1 would have incurred injuries to its roots. The excavation would have cut away some roots
on the south side, and created wounds to permit the invasion of wood-decay
fungi and other natural enemies into the root system. The weight of the concrete plinth and the
machine could have overburdened the soil to dampen normal root functions and
growth. In operation, the heat and air
flow generated by the machine would have dehydrated the leaves and imposed
additional stresses on tree growth.
By local standards, many Bombax
ceiba are older and have
better structure and health than T1, which is now considered to be damaged and
be in ‘poor’ health.
T2
- Ficus virens
T2 was snapped by Typhoon Fengshen on 25 June 2008, and irretrievably lost. It was a large tree, around 70 years old,
that measured 17 m tall by 24 m wide and had a trunk of 99 cm diameter. Gauged against the final dimensions of the
species and in view of the chronic site constraints, the tree had probably
attained its maximum size. The breakage
at the time of the typhoon occurred at the trunk base, leaving the above-ground
part of the tree lying en masse on the ground.
This has now been removed and T2 is considered to be dead.
T3 – Nageia nagi
T3 was
uprooted by Typhoon Fengshen on 25 June 2008. Previously it stood 20 m tall with an exceptionally
limited crown spread of merely 6 m and a trunk diameter of 40 cm and was
considered to be around 60 years old. A Nageia nagi of
similar height would have the ability to develop a crown up to 10 m
across. By local standards, T3 was
probably the largest and oldest specimen of the species, even though its
structure was not too representative of the species at its prime. Soon after the collapse, the tree was lifted
to the upright posture and supported by a propping system composed of eight
inclined steel bars connected to a steel ring around the trunk. In addition,
the tree was pulled by three guy wires linked to a higher position of the
trunk. Upon inspection in February 2009,
it was concluded that T3 had died.
T4 – Celtis sinensis
T4 was snapped
at about 1.8 m from the ground by Typhoon Fengshen on
25 June 2008, leaving a stump with
jagged fractured wood at its top.
It is a native broadleaf deciduous tree that commonly dwells in mature
local woodlands and can reach 16 m height.
An inspection in February 2009 concluded that prior to its snapping, T4
was already a hazardous tree that could have broken or toppled suddenly without
any warning. T4 is now considered to be
dead.
T5
– Mangifera
indica
T5 is a
very good specimen of Mangifera indica, judged to be about 60 years old and one of the
largest specimens of its kind in urban
Located in
the west edge of the parade ground of the Police Site, T5 is accommodated in a
small circular raised planter of 2.06 m diameter and 0.88 m tall, although the
soil level is sunken at only 0.28 m from the ground. The bulk of the critical root zone has to be
accommodated in the surrounding soil which has been completely sealed by the
impermeable concrete paving. Most roots
of the large tree are growing in the soil lying beneath the concrete cap. Root extension towards the building to the
west side is constrained by the foundation and the two-storey building also
restricts its crown spread. The tree is
well exposed to solar radiation on all sides with its crown standing above the
adjacent buildings and so avoiding being shaded. Shooting above the height of the surrounding
buildings, strong winds including typhoon could impose undue stresses.
Despite
some limitations, the health of T5 is rated as good but cannot be considered as
excellent due to the presence of many accumulated structural defects and
consequences of past mistreatments. It
is expected to have the potential to grow into an even bigger tree in due
course.
T6 – Aleurites
moluccana
T6 is a
large Aleurites moluccana
tree measuring approximately 16.2 m tall and 12.2 m crown span (close to the
biological potential for such a species) with a trunk diameter of approximately
57.4 cm (sub-optimal). It is considered
to be approximately 50 years old and in fair health. It is relatively unhampered by the
surrounding buildings and retaining wall, which also shelter
it from wind, and it is more shaded by proximal trees (T7, T8 and T9) than
buildings. T6 is accommodated in a small
circular planter that measures 2.7 m across and 0.44 m tall and poor soil
conditions are likely to be the principal obstacle to its optimal growth. The trunk is split into two limbs at a low
level, the north and south stems, and the junction of the two limbs has
developed a stable U-crotch. The south
stem is further split into two main branches higher up, also with a stable
U-crotch.
T6 has a
number of structural problems including branch crowding problem on the north
stem; a number of weak and unnatural branch attachment problems; infection by
wood-decay fungi in some branch wounds and stubs with degeneration into
cavities at some locations, weakening the ability of the affected branches to
support their own weight and resist the dynamic loading imposed by strong
winds; and unnatural and potentially unstable alignment in the main branch and
some other branches, rendering it susceptible to failure in some locations; and
confinement of the large structural roots radiating from the trunk base which
have now moved out of the small planter into the surrounding soil to cause
cracking and heaving of the concrete.
T7 – Aleurites
moluccana
T7 is a large Aleurites moluccana measuring approximately 15.4 m tall and 15.1
m crown spread with a trunk diameter of approximately 68.8 cm, close to the
biological potential of 80 cm. It is
estimated to be of similar age to T6 (about 50 years old) and is considered to
be in fair health. It is
accommodated in a small circular planter measuring 2.7 m across and 0.44 m tall
from which the roots have escaped, cracking the planter. The tiny soil volume of the planter and poor soil conditions are likely
to be the principal obstacle to its optimal growth. The site
condition of T7 is similar to that of its neighbour T6, in terms of exposure to
wind and reception of solar radiation.
T7 suffers from a number of structural defects that
are similar to those expressed by T6, including: a leafless tree skeleton with
weak union at the interface between the old and the new wood and an overall
unnatural tree scaffold and form; irregular branching which is potentially
unstable and contains weak connections that are prone to snapping in strong
winds; many branch stubs which are particularly susceptible to wood decay and
cavity development; some exceptionally long and heavy limbs with limited
tapering meaning the wood strength of these limbs is stressed and could be
prone to cracking or breakage; a canker on the upper surface of the fork
between the trunk and a low limb which could reduce wood strength to render the
limb hazardous; some leaf wilting and possible inspect pest infection.
T8 – Plumeria
rubra
T8 is a small, tilted and distorted Plumeria rubra tree measuring 5.48 m tall and 8.4 m crown diameter, supported by a
trunk of approximately 39.8 cm diameter.
It is estimated to be of similar age to T6 and T7 (about 50 years old)
and in fair health. Its growth has been
hampered mainly by T7 situated to its west, which overtops and presses
laterally against it and out-competes it for growth space and sunlight, meaning
almost all its branches are towards the east.
T8 is in a small circular, raised planter, measuring 1.8 m across and
0.42 m tall. Despite no cracking and
heaving of the planter rim and surrounding concrete paving, it is likely that
the roots have extended into the soil adjacent to the planter. Due to shading by its neighbour trees,
especially on the west by T7, it receives a limited amount of sunshine,
especially in the afternoon but the shielding could offer a certain degree of
protection from winds.
Previous limb removal has left decayed wood encircled
by peripheral callus tissues in one location which was improperly sealed by
cement. The base of the trunk on the
east side has developed unusual buckles which extend from the bark into the
wood but since the tree is relatively small and would not impose a lot of
loading on the curved trunk base, the buckles are unlikely to cause a
structural weakness problem. The crown
also has weak unions of joints caused by inappropriate treatment in the past,
and these are susceptible to breakage in strong wind.
T9 – Araucaria cunninghamii
T9
measures approximately 17.3 m tall with a slender trunk of approximately 37.2cm
diameter (both below average). It has
exceptionally low branching and foliage densities and its crown spread is
approximately 6.2 m with disturbed integrity and symmetry, reducing its
landscape quality and attraction. It is
estimated to be of similar age to T6, T7 and T8 (about 50 years old) and in
poor health.
T9 is
situated near the east edge of the open space, but it is far away enough from
buildings and the retaining wall to interfere with its growth. T7 to its west, and to a lesser extent T8,
could partly shade the tree in the afternoon and the tall tree could be exposed
to wind stresses. The circular planter
that holds T9, at 1.85 across and 0.85 m tall, is rather small for the tree and
the planter rim has been cracked, indicating the soil volume was inadequate to
accommodate the tree’s roots, with some of them spreading into the soil that
lies below the concrete paving. Four
companion trees that used to share the planter with T9 have now been removed
freeing T9 from crowding and competition stresses. The trunk has been covered by encircling barb
wires when the trunk diameter was smaller (to prevent climbing by prison
inmates). The subsequent secondary
thickening of the trunk has tightened the tension in the wires and embedded
them into the wood and the rusted wires could impose a constricting
strangulation on the trunk to interfere with the transport of plant food as
well as the wounds serving as portals for wood-decay fungal spores, insect
pests and moisture to enter the trunk.
T10 – Ficus
microcarpa
T10 is a wall tree that established spontaneously
without human assistance. It has
multiple trunks to support a full tree crown with dense branches and foliage,
in a normal posture similar to a ground-growing Banyan. The tree measures approximately 6 m tall with
a 6 m crown span. It is considered to be
about 20 years old and in good health.
T10 does not take up ground space having established on
an apparently vertical habitat. It is
located at the boundary of the Police and the Prison sites, at the junction
between the stone retaining wall and the adjacent, perpendicular,
free-standing, brick wall that marks the
Although T10 appears as if it could be easily
detached, toppled or uprooted and is prone to wind attack due to its relatively
exposed locality, like several hundred stone wall trees in
T10 is relying on the feeding roots that spread in
the retained soil lying behind the stone wall and the ground soil below the
brick wall to capture water and nutrient to sustain its life functions. If the soil has sufficient volume and
suitable property for plant growth, the wall tree can prosper, if not, its
growth will be retarded. Moreover, it is
relying on the lateral roots to grip the two wall surfaces, the gaps between
masonry blocks (for the stone wall) and the companion soil to secure a firm
anchorage. The growth rate and shoot
size of a wall tree relies on and echoes the spread and vigour of its
roots. Due to the highly limited site
and soil conditions, the growth rate of T10 has been suppressed and its
performance can be rated as average. The
habitat does not provide the right setting for T10 to thrive in the future and
the prognosis is that it will continue to exhibit average growth in the future,
should conditions remain the same.
Hong Kong has about 500 old stone retaining walls
mainly found in the Mid-levels of three old districts on Hong Kong Island,
namely Wanchai, Central and Western districts. A total of about 1200 trees of different age
and size are growing on the vertical habitats, most of which are Ficus microcarpa species.
T10 is considered a relatively small wall tree since the largest wall
tree of the same species has attained over 20 m in height, with many times the
crown size of T10.
T11 – Dracaena marginata
T11 is an exceptionally large specimen of Dracaena
marginata, reaching approximately 7.6 m high and
with a crown only able to extend away from the two adjacent buildings, tilting and
with a spread of approximately 4.6 m and branch and foliage densities slightly
below the norm. T11 has three trunks
with respective diameters of 16.4 cm, 10.1 cm and 10.4 cm, giving an aggregate
36.9 cm. It is up to 50 years old and
with stems demonstrating some signs of limited decay, it is considered to be in
poor health.
The tree is trapped in a tiny rectangular planter
situated next to the entrance of a building in the Police site. The planter measures 1.54 m by 0.8 m and is
0.95 m deep with compacted soil and limited drainage. The site is well sheltered and shaded on the
west and south sides, opens to a narrow canyon-like path to the north and is
more open to the east.
Table 4.3 Trees
within the Project Site
|
Tree ID |
Species Name |
Height (m) |
DBH (a) (m) |
Average Crown Spread (m) |
Health |
Proposed Treatment |
|
T1 |
Bombax ceiba 木棉 |
3.50 |
0.30 |
1.90 |
Very Poor (Damaged) |
Remove |
|
T2 |
Ficus virens 大葉榕 |
n/a |
n/a |
n/a |
Dead |
Remove |
|
T3 |
Nageia nagi 竹柏 |
19.80 |
0.40 |
3.80 |
Dead |
Remove |
|
T4 |
Celtis sinensis 朴樹 |
1.80 |
0.70 |
n/a |
Dead |
Remove |
|
T5 |
Mangifera indica 芒菓 |
17.90 |
0.78 |
23.80 |
Good |
Retain |
|
T6 |
Aleurites moluccana 石栗 |
16.20 |
0.57 |
12.20 |
Fair |
Retain |
|
T7 |
Aleurites moluccana 石栗 |
15.40 |
0.69 |
15.10 |
Fair |
Retain |
|
T8 |
Plumeria rubra 紅雞蛋花 |
5.48 |
0.40 |
8.40 |
Fair |
Retain |
|
T9 |
Araucaria cunninghamii 花旗杉 |
17.30 |
0.37 |
6.20 |
Poor |
Retain |
|
T10 |
Ficus microcarpa 細葉榕 |
6.00 |
0.20, Wall Tree |
6.00 |
Good |
Remove |
|
T11 |
Dracaena marginata 馬尾鉄 |
7.60 |
0.37 (b) |
4.60 |
Poor |
Retain |
|
Note: (a)
DBH is Diameter at Breast Height is standardised as the
trunk diameter at a height of 1300 mm above ground level in (b)
T11 has three trunks with respective diameters of 16.4 cm,
10.1 cm and 10.4 cm, thus each of the individual trunks of T11 qualifies it
as a tree. The aggregate DBH of the
three trunks is 36.9 cm. and this dimension has been reported in the table. |
||||||
4.6.5
Visually
Sensitive Receivers
As described in Section
4.4.2 a Visual Envelope was created to estimate areas from which the Site
is visible (Figure 4.6) and VSRs were then identified within this envelope (Figure 4.7).
After further desktop analysis and on-site inspection,
five VSR VPs around the Site were selected from which to prepare
photomontages. The VPs were chosen to
represent a range of VSR types and taken from locations all around the Site. They were also selected due to their being
adjacent to the Site without any screening meaning they were anticipated to be
receiving the most direct visual impact among the VSRs
identified and represent the worst possible visual impact of the Project. The VPs and VSRs
are mapped in Figure 4.7 and detailed
along with their sensitivity below, which is summarized in Table 4.4.
VPa
(VSR T2) – Central/ Mid-Levels Escalator above Hollywood Road: This
VP represents the VSR group of the users who are mostly local residents in the
mid levels often using the escalator to reach public transport such as MTR,
ferry or bus etc; tourists experiencing the urban life of Hong Kong; and locals
and tourists going out around Soho and Lan Kwai Fong for entertainment. This VSR/ VP has a
full view of the Site but also many alternative views of the urban district are
available and the value and quality of the existing view is medium. Although this group is classified as a
‘Travelling’ VSR the speed of transport is not fast since they are mainly
pedestrians and the high frequency with which many of the group travel on this
route render them more sensitive to change.
There are many people in this VSR during the operational hours of the
escalator (06:00-00:00) but outside these hours numbers reduce. This VSR has has
medium sensitivity.
VPb
(VSR H/O1) – Medium/ High Level Commercial/Residential Building(s) above
Hollywood Road: This VP represents the VSR group of both
white collars working in the offices at higher levels across Hollywood Road
from the Site as well as the residents in these buildings. They command a full, panoramic, southerly
view of the existing site and the stretch of hill behind and the value and
quality of their view from this height can be considered high. Since their windows face the Site and they
are close to the Site, they have few alternative views that do not incorporate
the Site itself. The view is not the top
priority of the workers as it will have a less important effect on their
perception of quality of life and
willingness to stay in these buildings but the residents represented here can
be assumed to be more reluctant to experience change, with any change affecting
their acceptability of their home environment. This VSR/VP is classified as
‘Residential/ Occupational’ and there are few VSRs
that fall into this group. While it
contains a mix of both more sensitive and less sensitive VSRs,
overall it is considered to have medium sensitivity.
VPc
(VSR T3) – Street Level at The Centrium on Arbuthnot
Road: This VP represents the VSR group of pedestrians that travel in the
corridor between Wyndham Street and Caine Road and
the receiver population is considered to be few. This group comprises white collar workers
from nearby offices and passers by going towards
VPd
(VSR H2) – Medium/High Rise Level Residential Building(s) on Chancery Lane: This
VSR/VP represents the local residents in the buildings just south of Chancery
Lane and is estimated to have relatively few residents in this small group of
buildings. They command a full,
panoramic, northerly view of the existing CPS which is the only area with a
sense of open space in close proximity and the value and quality of their
existing view is considered to be high.
This group is so close to the Site that alternative views similar to the
existing one are not available and any changes to the existing layout or
building heights could lead to subsequent impact on the group. The residents represented here can be assumed
to be reluctant to experience change, with any change affecting their acceptability
of their home environment. The VP has been chosen at the centre point of
these buildings. This VSR/VP is
classified as ‘Residential’ and has high sensitivity.
VPe
(VSR T4) – Street Level at
VPf
(VSR T5) – Street Level at
VSR
VSR
O1 Medium/High Level Commercial Building(s) (IFC Building): This VSR
represents workers in the higher levels of commercial buildings very far away
from the Site but still just close enough to notice the Site within their
view. Being at higher levels, the
existing views are panoramic and considered to be of high value and quality but
since this VSR is far away, the Site is only a small part of the existing view
and there are many alternative views available of the urban district. Overall their view is partial, often with
other buildings partially blocking the line of sight to the Site and the view
is not the top priority of these VSRs’ perception of
quality of life or their willingness to stay in these buildings. Although there are many commercial buildings
in this area with many workers, only a small number of such buildings have a
view of the Site such that overall the estimated receiver population is
considered few. This VSR is classified
as ‘Occupational’ and has low sensitivity.
VSR
O2 Medium/High Level Commercial Building(s) (
VSR
H1 Medium/High Level Residential Buildings in Mid-levels (
VSR
R1 Open/Park Area off
VSR
H3 Medium/High Level Residential Buildings on
Table 4.4 Sensitivity
of Visually Sensitive Receivers
|
VSR ID* |
VSR Name |
VP ID |
Value & Quality of Existing Views (High, Medium,
Low) |
Availability & Amenity of
Alternative Views |
Estimated Number of Receiver Population
(Very Few, Few, Many, Very Many) |
Degree of Visibility of Source(s) of
Visual Impact (Full & Panoramic, Full, Partial,
Glimpse) |
Receptor Sensitivity (Low, Medium,
High) |
|
T2 |
Central/ Mid-Levels Escalator above |
VPa |
Medium |
Alternative views available of the urban district. |
Many |
Full |
Medium |
|
H/O 1 |
Medium/High Level Commercial/Residential Building(s)
above |
VPb |
High |
Few alternative views available that do not
incorporate the Site. |
Few |
Full & Panoramic |
Medium |
|
T3 |
Street Level at The Centrium
on |
VPc |
Medium |
Alternative views available of the urban district. |
Few |
Full |
Medium |
|
H2 |
Medium/High Rise Level Residential Building(s) on |
VPd |
High |
No alternative views available that do not
incorporate the Site. |
Few |
Full & Panoramic |
High |
|
T4 |
Street Level at |
VPe |
Low |
Few alternative views available that do not
incorporate the Site. |
Very Few |
Full |
Low |
|
T5 |
Street Level at |
VPf |
Medium |
Alternative views available of the urban district. |
Many |
Full |
Medium |
|
T1 |
Street Level at |
n/a |
Medium |
Many alternative views available of the urban
district. |
Many |
Glimpse |
Low |
|
O1 |
Medium/High Level Commercial Building(s) ( |
n/a |
High |
Many alternative views available of the urban
district. |
Few |
Partial |
Low |
|
O2 |
Medium/High Level Commercial Building(s) ( |
n/a |
High |
Many alternative views available of the urban
district. |
Few |
Partial |
Low |
|
H1 |
Medium/High Level Residential Buildings in
Mid-levels ( |
n/a |
High |
Many alternative views available of the urban
district. |
Few |
Partial/Glimpse |
Medium |
|
R1 |
Open/Park Area off |
n/a |
Medium |
Alternative views available, mainly of the open/park
area. |
Very Few |
Glimpse |
Low |
|
H3 |
Medium/High Level Residential Buildings on |
n/a |
High |
No alternative views available that do not
incorporate the Site. |
Few |
Full & Panoramic |
High |
|
|
|
|
|
|
|
|
|
|
* T-Travelling ; H-Residential ; O-Occupational ;
H/O-Mixed Residential/Occupational ; R- Recreational |
|
|
|
||||
4.7.1
Potential Sources of Impacts
During the
construction phase, potential landscape and visual impacts may arise from:
·
works
for demolition of part of surrounding stone brick wall and construction of
entrance to service yard;
·
works
for demolition of existing building structures – the Garage, Workshop &
Laundry and General Office (Buildings 5, 16 and 18 in Figure 2.2);
·
works
for cleaning, re-pointing, dismantling and reinstatement of sections of
surrounding stone brick wall (see ‘Walls & Revetments’ of Section 3’s Annex A1 for details)
·
conservation,
repair and refurbishment work on the external façade of the retained buildings
including erection of scaffolding ([2]);
·
excavation
work including that for construction of basement in lower courtyard (see
Figure 2.8 for details);
·
new custom paving works throughout the Site
(see Figure 4.8a);
·
construction of new built structures (Old Bailey Wing, Arbuthnot Wing, new
footbridge);
·
construction of new pavement west of
·
site
hoarding - double steel, deck hoarding with covered walkway for construction of
the new buildings (Old Bailey Wing and Arbuthnot Wing) and single layer
hoarding for addition and alteration work within the Site;
·
temporary
stockpiling of construction and demolition materials and temporary storage of
construction equipment;
·
temporary
use of construction equipment on-site including cranes and vehicles;
·
off-site
construction traffic such as haulage of excavated materials;
·
temporary
traffic/ road diversions;
·
night-time
lighting; and
·
dust during dry weather.
During the operation phase, potential landscape and
visual impacts would be related to the following:
·
landscaping
works (eg new planting site, new green wall, existing
tree treatment);
·
repaired
and refurbished external façades of retained buildings (1);
·
operation
of new built structures (Old Bailey Wing, Arbuthnot Wing, new footbridge, new
access points);
·
new
pavement – west of
·
cleaned,
re-pointed, refurbished and repaired sections of external stone wall and
building façades; and
·
night-time lighting.
4.7.2
Landscape and Visual Mitigation Measures
during Construction and Operation Phases
The proposed mitigation measures to minimise the
potential landscape and visual impacts during the construction and operation of
the Project are described in Table 4.5 shown in the landscape master plan in Figure 4.8a which is further partially illustrated in Figure 4.8b. These
figures help clarify a number of these measures.
Since historically the Site has had very
little green landscape, it is possible to conserve the character of the Site
without integration of many additional soft landscape elements. The main spaces within the CPS that would allow
the integration of new landscape features are the Lower Courtyard between the
Police Headquarters and the Barrack Blocks, and the Upper Courtyard within the
Victoria Prison Compound (see Figure 2.2). One of the main components of the design
intention is to preserve the openness of both theses courtyards and they are
both significant spaces in terms of cultural heritage. It was therefore decided not to compromise
these spaces by adding significant soft landscape features within them, but rather
retain and enhance the existing. The
current recommended new planting strip at the Parade Ground to compensate for
the lost healthy wall tree and further enhance the Site, and the green wall
(covering an area of approximately 900 m2 with vegetation while
still revealing some elements of the original wall behind) at the Prison Yard
is considered an appropriate balance between the requirement for
visual/landscape mitigation and enhancement while conserving the character of
the Site.
With regards to the new landscape concept, the whole
Site has been regarded as a single entity, with all new proposed structures
considered in conjunction with the historical building context, constraints and
characters. Planning and provision of
landscape is treated as a Site wide approach and providing additional
greening features just to the individual new buildings and footbridge would not
be
an appropriate design
approach. With reference to
international examples, the integration (or otherwise) of landscaping is a
natural element of the overall design concept, instead of an imposed
requirement. The existence of
landscaping features will largely depend on a project’s specific context and
there are examples of where a prominent landscaping element is incompatible
with the design. The Centre Pompidou in
For this Project, the function and design of the new
buildings also limit the proposal for further greening features, such as green
roofs and planters. The art gallery on
the top floor of the Old Bailey Wing requires sky light diffusing into the
gallery while the cooling towers and chillers on the top floor of the Arbuthnot
Wing requires ventilation, such that a green roof for the new buildings is not
possible. The space below the Old Bailey
Wing is limited and the provision of planters may disrupt pedestrian
circulation while the grand stairs below the Arbuthnot Wing may act as a
semi-open space for cultural events with a historical backdrop of the D Hall
building façade and hence the provision of planters here is also not
appropriate.
As mentioned in Section
2, the architectural idea of the open footbridge is that it is a simple
extension of the Parade Ground and integrates into the whole Site design
concept. It is essential to carry
through the same hard-paved open-ground character of the Parade Ground and this
means the footbridge has been designed as a simple, minimal slab or platform
reaching out to the existing mid-level escalator. Moreover, to minimise the massing of the
footbridge (and hence the visual impact), the design only provides the minimum
width necessary for public flow. Any
additional landscape elements (e.g. plantings along the parapets of the
footbridge, vertical greening or toe wall planters at support column) would
cause extra loading on the footbridge and may mean its supporting structures be
wider, its overall width be wider due to planters and in general is would be
more massive and obstructive to the neighbouring historic building and Old
Bailey Street and any visually sensitive receivers in the vicinity. The handrail design tries to be as porous as
possible and any additional landscape elements would be more obstructive,
blocking some of the spaces. Moreover,
additional landscape elements would also add extra structural load, irrigation
and drainage systems etc which would make the footbridge more complex and more
difficult as there are not much structural supporting points available on Site.
Landscaping mitigation measures outside the CPS, for
example planting along the new pavement on
|
ID |
Mitigation Measure Description |
Funding Agency |
Implementation Agency |
Management/ Maintenance Agency |
|
Pre-Construction Phase |
||||
|
M1 |
Detailed Design
Considerations Hard landscape features
such as the location and form of landscape furniture will also be finalised
at this stage([3]). The building footprint
is to be reduced to the minimal practical size. . |
|
Detailed Design
Consultant |
|
|
Construction Phase |
||||
|
CM1 |
In-situ Tree Protection
- Cordon Zone (CZ)
|
|
Construction Contractor |
|
|
CM2 |
In-situ Tree Protection
- Advanced & Phased Root Pruning
|
|
Trained Arborist or Horticulturist Contractor |
|
|
CM3 |
In-situ Tree Protection
- Foliage cleansing system |
|
Landscaper Contractor |
|
|
CM4 |
In-situ Tree Protection
- Monthly inspection |
|
Trained Arborist or Horticulturist Contractor |
|
|
CM5 |
Light Control |
|
Construction Contractor |
|
|
CM6 |
Compensatory
/Enhancement Tree Planting The new tree strip
should be 4 m wide and covered by porous unit pavers to permit the entry of
rain and irrigation water and air exchange between the soil and the
atmosphere. The unit pavers should be
supported by small columns to create a vault-like structure so as to avoid
compaction of the underlying soil due to pedestrian trampling. The unit
pavers will be movable to provide access to the soil underneath so that
fertilizers and conditioners could be added on a regular basis. The air conditioner unit currently
located near the proposed planting site should also be removed. This new tree planting site should also be provided
with proper irrigation. Pursuant to the
“Environment, Transport and Works Bureau Technical Circular (Works) No.
3/2006 Tree Preservation”, the compensation ratio should preferably be 1:1
according to trunk girth. T10 has a
DBH of 20 cm (Table 4.3),
and it is proposed that six trees of heavy standard size be planted, each
with a DBH of around 10 cm and root balls of not less than 0.75 m diameter
and 0.75 m depth,. Since the
aggregate DBH of the new trees would be 60 cm, the rate of compensation is
equivalent to three times the DBH of T10, far beyond the requirements -
The six replacement trees should be planted in the new
tree strip in two staggered rows, maximising distance between each tree to
avoid mutual interference in the future.
It is recommended that the species selected should have a small
final dimension of less than 10 m height given the proximity to built
structures such as the retaining wall and buildings. |
|
Landscaper Contractor |
|
|
CM7 |
Vertical Greening As such it is
recommended that the inner southern wall of the Site be planted as a green
wall. The plantings should be inserted
in between each of the large protruding piers and an offset be made from both
the top and bottom edge so that old and new are equally visible. An independent frame should be strategically
positioned in order to ensure minimal disturbance to the original wall, and
provide the main structural support and planting surface for the green
wall. The frame on to which the new
green will be planted should contain its own irrigation system so that
moisture for the plants will remain mainly on the planting surface and not
the exiting wall behind. The planting
chosen should be appropriate to the |
|
Landscape Contractor |
|
|
CM8 |
New Custom Paving |
|
|
|
|
Operation Phase |
||||
|
OM1 |
In-situ Tree Protection
- Quarterly inspection |
|
Trained Arborist or Horticulturist Contractor |
|
|
OM2 |
Soft Landscape
Maintenance |
|
Landscaper Contractor |
|
|
OM3 |
Architectural
Maintenance |
|
|
|
|
OM4 |
Light Control |
|
Construction Contractor |
|
4.7.3
Landscape Impact Assessment
The Project impacts just three of the nine LRs and two of the seven LCAs
identified in the Study Area. These
impacts are described below, considering the potential sources of impact listed
in Section 4.7.1. The magnitude of change before mitigation is
determined to be negligible, small, intermediate or large and adverse unless
stated otherwise. Using the sensitivity
ratings from Section 4.6.2 and 4.6.3 and the matrix explained in Table 4.1, the impact significance is also
stated and is assumed to be adverse unless stated otherwise. This magnitude of change ratings are
summarised in Table
4.6, while Table
4.7 summarises significance of impacts both before and upon
mitigation.
Landscape Impact Before Mitigation
The six landscape resources LR2 (Commercial/
Residential/ Institutional Building Area), LR5 (Public Park/ Recreational
Area), LR6 (Hong Kong Zoological & botanical Garden), LR7 (Vegetated
Slope), LR8 (Natural Woodland on Hillside) and LR9 (Temple Area) are not
impacted by the Project and neither are the five landscape character areas LCA2
(Park Landscape), LCA3 (Medium/High-rise Commercial Urban Landscape), LCA5
(Central Civic Administration Landscape), LCA6 (Natural Hillside Landscape) and
LCA7 (Major Transport Corri
During operation, the
impact on the CPS driveway will be negligible.
A very short length of road at the northern end of
LR3 Buildings within
During operation, most of
buildings (16/19) will have been retained and overhauled and will change from
being moribund and decaying to used, thus improving this landscape’s amenity
value. The new structures within this LR
take up under a third of the building space within the Site and while of a
different aspect to the existing buildings still confer a similar utility. The new entrances and wall will be compatible
with the surrounding landscape once construction works have been completed, but
as described in ‘Tree Impact Assessment’ one wall tree (T10) will have been
lost. Overall during operation once
new features have been built and works finished the impacts on this LR will
have diminished compared to construction phase. The magnitude of change is considered
intermediate and since this LR has medium sensitivity the significance
of impact before mitigation is moderate.
LR4 Open Space within
During operation, all
stockpiled materials will have been removed and the excavated area closed
over. The majority of this LR will have
been re-instated with new, porous patterned, high quality concrete custom paving
while a small part of it will have undergone light repairs (refer to the
existing concrete paving in Figure 4.8a). In
addition to the removal of some dead or damaged trees these measures will
provide a small beneficial impact on the landscape and there are no adverse
impacts during operation During
operation this LR is not considered to be very similar to before
construction began and the magnitude of change is considered to be negligible
overall. This LR has high
sensitivity and the significance of impact before mitigation is
insignificant.
LCA1 Historical Landscape: The CPS makes up the majority of this
LCA within the Study Area and 69% of this LCA is impacted by the Project. During construction, impacts include demolition of three of the nineteen buildings (Garage,
Workshop & Laundry and General Office) in the CPS, the construction of two
modern buildings (Old Bailey Wing and Arbuthnot Wing) with alternative aspect
to the Edwardian/ Victorian style buildings.
The Parade Ground and Prison Yard will be impacted by major and minor
excavation works respectively and the stockpiling and storage of materials and
operation of equipment my also impact this LCA.
Trees within the CPS in this LCA will be impacted as detailed in ‘Tree
Impact Assessment’, with four dead or damaged trees and one healthy wall tree
being removed but all other trees being retained. The construction of new site entrances will
impact sections of the CPS boundary wall, including the removal of one healthy
wall tree (T10) (See in ‘Tree Impact Assessment’). The retained buildings will undergo conservation,
repair and refurbishment work on the external façade as described in Section 4.7.1 including all windows
being repaired, replaced or overhauled. During construction the magnitude of change
is large and since this LCA
has high sensitivity the impact before mitigation is significant.
During operation, most of
buildings (16/19) and all the open space will have been retained and
overhauled/repaved and will change from being derelict to used and confer
improved landscape value. The new
buildings will change this LCA adding a different and more modern, aspect to
the LCA. The new entrances will be
compatible with the surrounding landscape.
As described in ‘Tree Impact Assessment’ following, one wall tree (T10)
will be permanently lost but the remaining healthy trees retained and dead or
unhealthy trees cleared. Overall during
operation the magnitude of change is considered intermediate. This LCA has high sensitivity and the significance
of impact during operation is considered to be less than that during
construction, and before mitigation is moderate.
LCA4 Residential/
Commercial/ Urban Landscape:
This LCA is over double the size of any other LCA in the Study Area and overall
a very small actual area (approximately 0.01 ha) o f this LR, which is also a
relatively very small area (0.02%) of it is impacted by the Project. During construction, this LCA will be
impacted by the slight enlargement of pavement at the northern end of
During operation, the character of the area will not
have been changed due to the new pavements. The magnitude of change is negligible
and the impact is therefore insignificant.
Tree Impact Assessment
The existing trees have not had proper tree care for
many years. Except T10 which is
recommended for felling, and T1, T2, T3 and T4 which were damaged or destroyed
by typhoon in 2008 and whose remains should be removed, the remaining six trees
could benefit from a systematic programme of tree care to tackle a host of
accumulated arboricultural problems. The details of proposed tree care actions are
explained below.
T1 – Bombax ceiba
T1 is a broken tree, struggling to survive by
developing some unnatural water sprouts and in poor health. Although it displays some apparent signs of
recovery, they indicate the last-resort physiological and morphological
responses of a tree that has been pushed to the extreme. Due to the massive structural losses and
associated injuries, there is no hope that the tree regaining its health and
restoring its natural neat and layered pagoda tree form, which in conjunction with
its large reddish bloom, constitute the raison d’être for planting Bombax ceiba. With the loss of the leader trunk that would
normally dominate the tree structure from base to tip, and dim prospect of
forming a replacement leader, the tree’s landscape and amenity value has been
permanently depleted. In addition, there is a high risk of invasion by
wood-decay fungi at the existing trunk breakage which would lead to a hazardous
tree situation in due course.
Judging from the height and trunk diameter of the
tree before it was snapped, and the site conditions, T1 is considered to be
around 25 years old, hence it is a relatively recent
addition to the Site with limited historical value. The historical association with the cultural
heritage is at best tenuous and may not be construed as significant. By local standards, many Bombax ceiba are
notably older, stronger and have better structure and health than T1. The present emaciated and truncated state is
incongruous with the condition of the adjacent heritage buildings which are to
be renovated and repaired where necessary.
Considering the above assessment and taking into
account arboriculture and staff and visitor safety, it is suggested T1 be
removed.
T2 - Ficus virens
Before its collapse, T2 was
beset by some wood decay in its trunk, as indicated by photographs from an
October 2007 tree report. It is now a
dead and should be removed. Despite no
compensatory planting being required, it is suggested that the entire strip of
land that previously accommodated T1 to T4 should be revamped to provide a
planting site with improved soil conditions for future tree growth and six
trees be planted here, as detailed in CM6 of Table 4.5.
T3 – Nageia nagi
T3 is
now considered to be dead as a result of toppling by Typhoon Fengshen which brought massive root breakage and injuries
and should be removed. Despite no compensatory
planting being required, it is suggested that the entire strip of land that
previously accommodated T1 to T4 should be revamped to provide a planting site
with improved soil conditions for future tree growth and six trees be planted
here, as detailed in CM6 of Table 4.5.
T4 – Celtis sinensis
T4 is now
considered to be dead and the stump of T4 should be removed with the major
structural roots below the trunk base being extracted by a stump grinder. Despite no compensatory planting being
required, it is suggested that the entire strip of land that previously
accommodated T1 to T4 should be revamped to provide a planting site with
improved soil conditions for future tree growth and six trees be planted here,
as detailed in CM6 of Table
4.5.
T5
– Mangifera
indica
T5 is currently in good health but past branch
pruning works appear to be piecemeal and low quality. T5 would now benefit form a thorough crown
cleaning exercise to target the removal of dead, decayed, diseased or
cankerous, cracked or fractured, crossed and crooked or kinked branched as well
as branches with particularly weak joints.
This should follow a thorough tree inspection for the presence of such
branches as well as for wood decay, cankerous and debarking problems and any
weak branches that may be hazardous.
Treatment should strictly follow the guidelines recommended by the
International Society of Arboriculture and be conducted by a competent and
qualified arborist. The planter and soil
conditions for the tree should also be improved to ensure sustained healthy
growth.
T6 – Aleurites
moluccana
T6 is
currently in fair health but similarly to T5, has not received
professional tree care for a long time and has
accumulated many problematic structural flaws and consequences of
mistreatments, some of which could render the tree potentially unstable. It needs a thorough crown cleaning treatment
as detailed for T5, and equally planter and soil conditions for the tree
should also be improved to ensure sustained healthy growth
T7 – Aleurites
moluccana
T7 is considered to be in fair health but has
accumulated many structural defects due to improper and severe branch pruning
in the past. It has not had a
professional crown cleaning treatment for a very long time and needs
a thorough crown cleaning treatment as detailed for T5. T7 should be checked closely to see if the insect pest infestation is
active, and if so, extermination treatment such as spraying with an approved
insecticide should be applied. Similarly
to T5 and T6, planter and soil conditions for the tree should also be improved to
ensure sustained healthy growth.
T8 – Plumeria
rubra
T8 is in fair health but has been subjected to
unnecessary, frequent and improper branch removals in the past. The competition with its neighbouring tree,
T7, is the main cause of the distorted tree form and will not be rectified by
natural or artificial means. No action
is recommended to correct the tree posture.
The large number of old wounds, weak joints and
unnaturally angled branches caused by improper treatment in the past cannot be
remedied properly without causing an unacceptable reduction of T8’s biomass and
living tissues. The recommendation is
therefore to forgo the major surgeries and tolerate the structural defects so
it can continue to live. A light pruning
exercise is recommended to remove the most critical branches that are decayed,
diseased or competing, following the crown treatment approach explained for
T5. The amount of wood and foliage to be
pruned away should be kept to the minimum to preserve the overall tree form and
vitality of the tree.
Similarly to T5, T6 and T7, planter and soil
conditions for the tree should also be improved to help its sustained healthy
growth.
T9 – Araucaria cunninghamii
T9 is in
poor health, and it is unlikely to regain its vigour whilst trapped in the soil
bondage, with a concrete cover around the planter. This cover should be removed and planter and soil
conditions for the tree improved to help its revitalization. In addition, every bit
of the rusty barb wires winding around and partly embedded in the trunk should
be carefully extracted and removed with the wounds cleaned with a brush to get
rid of residing residues.
T10 – Ficus
microcarpa
T10 is considered to be about 20 years old and in
good health. The key factors that permit
meritorious wall tree growth are a wall that is tall and long, old, composed of
large stones, made of irregular stones (rubble), has a large amount of joints
between masonry blocks, and is sheltered by adjacent notably taller buildings. These inherent wall attributes cannot be
found on the subject wall and it is concluded that future growth of T10 would
be at a sluggish rate.
The adaptive use of the heritage site requires
satisfying some fundamental building, safety and functional requirements. Due to elevation difference of the sloping
site, at present the only vehicular access is at
The feasibility of installing the new access road
whilst preserving T10 has been considered.
The proposed gap for the access road is the minimum required for
emergency vehicle access and the entire width of the gap from the ground
upwards has to remain clear of obstacles.
The main branches of T10 begin to grow outwards towards the proposed gap
just above the brick wall at about 3 m from the level of Old Bailey Street and
its overhanging branches would limit the head room of the proposed road, thus
disqualifying it as an emergency access.
In situ preservation of T10 would also have to involve protection of
both walls and the companion soil in a holistic package. Any damage to the two walls and their
companion soil would injure or cut the lateral and feeding roots reducing the
water and nutrient supply to the wall tree and seriously compromising its
stability. Since creating the access
road would damage the roots on the brick wall and in the ground soil T10 would
be weakened and destabilized. It is
therefore concluded that the co-existence of the new road and T10 is not
possible.
Since T10 cannot be retained, the option of
transplanting it has also been considered.
To move T10, two requirements would need to be fulfilled: (1) taking two
wall segments of sufficient dimension to keep most of the lateral roots; and
(2) taking two root balls respectively for the retained soil and the ground
soil, each of which must contain a sufficient volume of companion soil together
with their constituent feeder roots.
During the transport stage, the four entities plus the above-ground part
of the tree (“the shoot”) would need to be moved en masse as one unit without
any relative movement to each other in the course of lifting and conveyance, to
avoid their breakage or disintegration.
These stringent requirements are technically very difficult to
accomplish and are unlikely to be satisfied.
In addition, any attempt to move the four entities would demand heavy
lifting machines which require a wide road access, a flat and strong platform,
and a large amount of manoeuvring space.
These indispensable conditions are unlikely to be satisfied given the
cramped condition of the tree site and the adjacent steeply-sloping and narrow
The size, tree form, performance, and landscape and
amenity value of T10, in comparison with the large and robust wall trees in
other parts of the city, are relatively low.
Due to site and technical constraints, in situ preservation and transplanting
cannot be recommended. Overall, considering
alternative locations of the new access road would require the demolition of
high quality and culturally valuable heritage structures, the felling of T10, a
relatively average wall tree, is deemed an acceptable option.
T11 – Dracaena marginata
T11 is in poor health. The tree could be tidied up by the removal of
a small amount of the broken or brown leaves and branches. The debris on the soil surface should be
removed. The surface compacted soil
could be carefully removed down to about 5 cm. The soil could be improved by
loosening to facilitate aeration, infiltration and drainage. Great care should be exercised in these soil
operations to avoid damaging the roots.
A 5 cm layer of topsoil composed of 1:1 volume ratio of completely
decomposed granite and mature organic compost could be added to form a surface mulch.
Landscape Impact Upon Mitigation
The potential
significances of residual landscape impacts during construction and operation
phases, after mitigation, are outlined below considering mitigation measures
described in detail in Table 4.5. The significance of impacts at both construction and operation phases,
without and upon mitigation, are
summarised in Table 4.7. All impacts are considered adverse unless
stated otherwise. For all those LRs/LCAs not impacted by the Project (as listed
previously), the residual impact at both construction and operation is insignificant
LR3 – Buildings within
Declared Monument. The
impact on this LR without mitigation is significant during construction and
moderate during operation (see Landscape Impact Before
Mitigation). Implementing detailed
design considerations (M1), compensatory tree planting for the loss of T10
(also see ‘Tree Impact Assessment’) and vertical greening such as a green wall
to the south of the Site, the residual impact during construction will
be reduced to moderate. There
will be some beneficial as well as adverse impacts during operation and
as well as the mitigation measures mentioned, if architectural maintenance is
carried out, the residual impact is considered to reduce to slight
both at day 1 and year 10.
LR4
– Open Space within Declared Monument. The impact on this LR without mitigation is significant during construction
and insignificant during operation (see Landscape Impact Before
Mitigation). By implementing
detailed design considerations, in-situ tree protection, enhancement tree
planting (no requirement to compensate for the four dead or damaged trees
lost. Also see ‘Tree Impact Assessment’)
and vertical greening such as a green wall to the south of the Site, the residual
impact during construction will be reduced to moderate.
If further in-situ tree protection and soft-landscape
maintenance is implemented, along with architectural maintenance of the new
paving, in addition to the mitigation measures at construction, the residual
impact during operation will become slightly beneficial by year 10 when the
in-situ trees have benefitted from the further protection and maintenance and
the green wall plants will have matured.
LCA1 – Historical Landscape: The
impact on this LCA without mitigation is significant during construction and
moderate during operation. During
construction, implementing detailed
design considerations, in-situ tree protection, tree planting in the new
planting site to compensate for the loss of T10 and generally enhance the
landscape after removal of the trees that were dead or damaged by a Typhoon in
2008, vertical greening such as planting of a green wall to the south of the
Site, the residual impact during construction will be reduced to moderate. There will be some beneficial as well
as adverse impacts during operation and as well as the mitigation
measures mentioned, if architectural maintenance is carried out, the
residual impact during operation is slight both at day 1 and year
10.
LCA4 Residential/ Commercial/ Urban Landscape: The impact
on this LCA without mitigation is slight during construction and insignificant
during operation. Construction is
assumed to be carried out following standard good practise, and the
implementation of detailed design considerations (M1) is suggested to minimize
the project footprint on this LCA. As
described for LR1 however, there will still be a slight residual impact at
construction.
Table 4.6 Magnitude of Impact on LRs and LCAs
affected by the Project, Before Mitigation
|
ID |
Description |
Total Area in Study
Area (ha) |
Area falling
within at Project Site (ha) |
Percentage
within Project Site with respect to Study Area (%)* |
Description of
Impacts (Construction/ Operation) |
Duration of Impact - Construction (no mitigation) |
Duration of Impact - Operation (no mitigation) |
Compatibility of Project |
Magnitude of Change - Construction (no mitigation) |
Magnitude of Change - Operation (no mitigation) |
|
LR1 |
Transport Route |
20.45 |
0.06 |
0.29 (very small) |
As described in Section 4.7.3 of text. |
Temporary & Reversible |
Permanent and irreversible |
Compatible; impacted by construction/renovation of same LR type. |
Small |
Negligible |
|
LR2 |
Commercial/ Residential/ Institutional Building Area |
68.92 |
0.00 |
0 |
n/a |
n/a |
n/a |
n/a |
Negligible |
Negligible |
|
LR3 |
Buildings within Declared Monument |
0.71 |
0.71 |
100 (large) |
As described in Section 4.7.3 of text. |
Temporary & Reversible |
Permanent and irreversible |
Partly compatible; improvement to old buildings, demolition of three
buildings to make way for construction of two modern buildings of new aspect. |
Large |
Intermediate |
|
LR4 |
Open Space within Declared Monument |
0.70 |
0.70 |
100 (large) |
As described in Section 4.7.3 of text. |
Temporary & Reversible |
Permanent and irreversible |
Compatible; all open space retained. |
Large |
Negligible |
|
LR5 |
|
1.25 |
0.00 |
0 |
n/a |
n/a |
n/a |
n/a |
Negligible |
Negligible |
|
LR6 |
|
6.10 |
0.00 |
0 |
n/a |
n/a |
n/a |
n/a |
Negligible |
Negligible |
|
LR7 |
Vegetated Slope |
3.66 |
0.00 |
0 |
n/a |
n/a |
n/a |
n/a |
Negligible |
Negligible |
|
LR8 |
Natural |
2.97 |
0.00 |
0 |
n/a |
n/a |
n/a |
n/a |
Negligible |
Negligible |
|
LR9 |
|
0.07 |
0.00 |
0 |
n/a |
n/a |
n/a |
n/a |
Negligible |
Negligible |
|
LCA1 |
Historical Landscape |
2.11 |
1.46 |
69 (large) |
As described in Section 4.7.3 of text. |
Temporary & Reversible |
Permanent and irreversible |
Partly compatible; retention of all open space and improvement to
retained buildings, demolition of three buildings to make way for
construction of two modern buildings of new aspect. |
Large |
Intermediate |
|
LCA2 |
Park Landscape |
6.88 |
0.00 |
0 |
n/a |
Negligible |
Negligible |
n/a |
Negligible |
Negligible |
|
LCA3 |
Medium/High-rise Commercial Urban Landscape |
27.28 |
0.00 |
0 |
n/a |
Negligible |
Negligible |
n/a |
Negligible |
Negligible |
|
LCA4 |
Residential/ Commercial Urban Landscape |
54.76 |
0.01 |
0.02 (very small) |
As described in Section 4.7.3 of text. |
Temporary & Reversible |
Permanent and irreversible |
Compatible; impacted by construction/renovation of pavement/wall, a common
resource within this LCA. |
Small |
Negligible |
|
LCA5 |
Central Civic Administration Landscape |
7.32 |
0.00 |
0 |
n/a |
n/a |
n/a |
n/a |
Negligible |
Negligible |
|
LCA6 |
Natural |
2.98 |
0.00 |
0 |
n/a |
n/a |
n/a |
n/a |
Negligible |
Negligible |
|
LCA7 |
Major Transport Corridor |
3.50 |
0.00 |
0 |
n/a |
n/a |
n/a |
n/a |
Negligible |
Negligible |
|
|
|
|
|
|
|
|
|
|
|
|
|
* This is indicative of the scale of the Project relative to that particular
LR/LCA. Less than 5% was considered very small, 5% to <15% small, 15% to
<40% moderate and 40% and above large. |
|
|
||||||||
Table 4.7 Significance
of Landscape Impacts in Construction and Operation Phases, before and after
Mitigation
|
LR ID |
Landscape Resource/ Landscape Character |
Sensitivity (Low, Medium, High) |
Magnitude of Change BEFORE Mitigation (Negligible,
Small, Intermediate, Large) |
Impact Significance BEFORE Mitigation
(Insignificant, Slight, Moderate, Significant) |
Recommended Mitigation Measures |
Residual Impact (Insignificant, Slight, Moderate,
Significant) |
||||
|
|
|
|
Construction |
Operation |
Construction |
Operation |
Construction |
Operation - Day
1 |
Operation - Year
10 |
|
|
LR1 |
Transport Route |
Low |
Small |
Negligible |
Slight |
Insignificant |
M1 |
Slight |
Insignificant |
Insignificant |
|
LR2 |
Commercial/ Residential/ Institutional Building Area |
Low |
Negligible |
Negligible |
Insignificant |
Insignificant |
n/a |
Insignificant |
Insignificant |
Insignificant |
|
LR3 |
Buildings within Declared Monument |
Medium |
Large |
Intermediate |
Significant |
Moderate |
M1, CM7 |
Moderate |
Slight |
Slight |
|
LR4 |
Open Space within Declared Monument |
High |
Large |
Negligible |
Significant |
Insignificant |
M1, CM1-4, CM6, CM7, CM8, OM1-2 |
Moderate |
Insignificant |
Slightly beneficial |
|
LR5 |
|
Medium |
Negligible |
Negligible |
Insignificant |
Insignificant |
n/a |
Insignificant |
Insignificant |
Insignificant |
|
LR6 |
|
High |
Negligible |
Negligible |
Insignificant |
Insignificant |
n/a |
Insignificant |
Insignificant |
Insignificant |
|
LR7 |
Vegetated Slope |
Medium |
Negligible |
Negligible |
Insignificant |
Insignificant |
n/a |
Insignificant |
Insignificant |
Insignificant |
|
LR8 |
Natural |
High |
Negligible |
Negligible |
Insignificant |
Insignificant |
n/a |
Insignificant |
Insignificant |
Insignificant |
|
LR9 |
|
High |
Negligible |
Negligible |
Insignificant |
Insignificant |
n/a |
Insignificant |
Insignificant |
Insignificant |
|
|
|
|
|
|
|
|
|
|
|
|
|
LCA1 |
Historical Landscape |
High |
Large |
Intermediate |
Significant |
Moderate |
M1, CM1-4, CM6, CM7, CM8, OM1-3 |
Moderate |
Slight |
Slight |
|
LCA2 |
Park Landscape |
High |
Negligible |
Negligible |
Insignificant |
Insignificant |
n/a |
Insignificant |
Insignificant |
Insignificant |
|
LCA3 |
Medium/High-rise Commercial Urban Landscape |
Medium |
Negligible |
Negligible |
Insignificant |
Insignificant |
n/a |
Insignificant |
Insignificant |
Insignificant |
|
LCA4 |
Residential/ Commercial Urban Landscape |
Low |
Small |
Negligible |
Slight |
Insignificant |
M1 |
Slight |
Insignificant |
Insignificant |
|
LCA5 |
Central Civic Administration Landscape |
High |
Negligible |
Negligible |
Insignificant |
Insignificant |
n/a |
Insignificant |
Insignificant |
Insignificant |
|
LCA6 |
Natural |
High |
Negligible |
Negligible |
Insignificant |
Insignificant |
n/a |
Insignificant |
Insignificant |
Insignificant |
|
LCA7 |
Major Transport Corridor |
Low |
Negligible |
Negligible |
Insignificant |
Insignificant |
n/a |
Insignificant |
Insignificant |
Insignificant |
4.7.4
Visual Impact Assessment
The selection of Scheme B for the Project and
proposed design of the two new buildings and the new footbridge have been
discussed in Section 4.5 and is
further elaborated on in Section 2. It should be noted that the massing and style
of the new buildings was dictated by the zoning envelope and height restriction
set for potential new buildings under the OZP and the internal space (floor
area and ceiling height) needed for the proposed uses. The design takes the approach to set back
from the maximum building envelope so as to minimise disturbance to the
adjacent historic buildings and leave them intact. Hence in terms of the massing and style, the
new buildings will be compatible in terms of a visual (and cultural heritage)
perspective.
The visual impacts due to the current
Project on each VSR group identified are described below, referring to
potential sources of impact listed in Section
4.7.1. The magnitude of change
before mitigation is determined to be negligible, small, intermediate or large
and adverse unless stated otherwise.
Using the sensitivity ratings from Section
4.6.5 and the matrix explained in Table 4.1, the impact significance is also
stated. This magnitude of change ratings
are summarised in Table 4.8 while Table 4.9 summarises significance of impacts both
before and upon mitigation.
Visual Impact Before
Mitigation
VPa (VSR T2) – Central/ Mid-Levels Escalator above
During operation, the existing buildings
will have improved visual amenity through their refurbished façades which will
be a positive change for this VSR. This
group of VSRs will not be able to see the new buildings (Old Bailey wing and
Arbuthnot wing), but is next to the new footbridge. The current design of the footbridge is open,
as described in Section 4.5, and
allows for this group of VSRs to still be able to
partially see up
Part of Figure
4.9
illustrates the existing view from this VP as well as showing a photomontage of
the view during operation, (although the photomontage has incorporated design
considerations and is not considered totally unmitigated).
During operation, the overall magnitude
of change before mitigation is large.
This group has medium sensitivity, and given the design and
compatibility of the footbridge, the visual impact is considered less
than during construction and is moderate.
VPb (VSR H/O1) – Medium/ High Level Commercial/Residential
Building(s) above Hollywood Road: During the
construction, this group are very close to the Site and will mainly be impacted
by the construction works around the Parade Ground, including excavation work
for construction of a basement as well as fitting new custom paving, on-site
equipment works and possibly temporary stockpiling of materials. No new buildings will be constructed in this
area, but the parade ground will be partially excavated and the existing
buildings will be refurbished and should scaffolding need to be erected this
will cause visual impact on this VSR.
Some of the VSRs may be partially able to see
the construction of the new footbridge, connecting to the escalator
corridor. The main structure will be
constructed off-site and installed ready-made, meaning duration of disruption
will be minimal. Work may also be
carried out outside peak hours ie at night when
workers in this VSR group are not around.
The construction works to the south of the Site, where the new buildings
will be erected, are party blocked by the Barracks building and will only be
visible for work to higher elevations. During
construction, the magnitude of change before mitigation is large. Since this group has medium sensitivity, the visual
impact is significant.
During operation, the existing buildings
will have improved visual amenity through their renovated façades and the
Parade Ground will have new porous paving, all of which will be a positive
change for this VSR. The tops of the new buildings (Old Bailey
wing and Arbuthnot wing) will be visible in the mid-distance and permanently
change the view, but they only block a minimal part of the existing view and
are compatible with the general high rise blocks surrounding them within the
view outside the Site. They are also
compatible with the view within the Site given the set back from the existing
buildings, as described previously. The
new footbridge may be partially visible to some of the VSRs
in this group, but will only minimally block part of their existing view.
Figure 4.10 illustrates the existing view from this
VP as well as illustrating the proposed view during operation at day 1 with no
mitigation measures in place.
During operation,
the overall magnitude of change before mitigation is intermediate. Since this group has medium sensitivity, the visual
impact is moderate.
VPc (VSR T3) – Street Level at The Centrium
on Arbuthnot Road: During the construction, this group will
be affected by the demolition of the Workshop & Laundry structures to make
way for the construction of the ‘Arbuthnot Wing’ new building and the site
hoarding associated with this work as well as the minor pavement work to the
west of Arbuthnot Road. This group may
also be able to see other works along the east and par t of the north and south
Site boundary walls, including those associated with the construction of a new
entrance at Bauhinia House and the cleaning and re-pointing of the wall. They may also be affected should scaffolding
need to be erected to carry out any refurbishment work on the existing building
external façades eg E Hall and Magistracy. The Site boundary wall will shield these VSRs from much of the construction work being carried out
within the Site which will therefore not affected them. During construction, the magnitude
of change before mitigation is large.
Since this group has medium sensitivity, the visual impact is
significant.
During operation, the Arbuthnot Wing will be
a prominent new feature to this VSRs view to the
south of the Site, and the new entrance at Bauhinia House and new, narrow
pavement running to the west of
Figure 4.11 illustrates the existing view from this
VP as well as illustrating the proposed view during operation at day 1 with no
mitigation measures in place. The VP has
been chosen to represent the worst case scenario for this VSR group.
During operation,
the overall magnitude of change before mitigation is large. Since this group has medium sensitivity, and
although the visual impact is considered less than during construction
and some of the change will be beneficial it is still considered significant
without mitigation.
VPd (VSR H2) – Medium/High Rise Level Residential
Building(s) on Chancery Lane: During
the construction, this group are very close to the south of the Site and
will mainly be impacted by the construction works around the Prison Yard,
including the demolition of General Office and the Workshop & Laundry
buildings and the construction of the new Old Bailey Wing and Arbuthnot Wing
and the associated hoarding. In addition
the minor excavation work and fitting of new custom paving will be visible as
well as some on-site equipment and possibly temporary stockpiling of
materials. They may also be affected
should scaffolding need to be erected to carry out any refurbishment work on
the existing building external façades. During
construction, the magnitude of change before mitigation is large. Since this group has high sensitivity, the visual
impact is significant.
During operation, the new buildings (Old Bailey Wing and Arbuthnot
Wing) will be clearly visible and be the main change in view for this VSR. The extent to which the new buildings block
the view will depend on where along
Figure 4.12 illustrates the existing view from this
VP as well as illustrating the proposed view during operation at day 1 with no
mitigation measures in place.
During operation,
the overall magnitude of change before mitigation is large. Since this group has high sensitivity, the visual
impact is significant.
VPe (VSR T4) – Street Level at Old Bailey Street/
Chancery Lane Junction: During
the construction, this group are right next to the Site and being at
street level the existing Site boundary wall will shield these VSRs from the majority of the construction work being
carried out within the Site. They will
be partly impacted by the demolition of the General Office and the Workshop
& Laundry buildings and the construction of the new Old Bailey Wing and
Arbuthnot Wing and the associated hoarding.
However they will only be able to see works associated with one of the
new buildings from any one location, rather than both together. They will also be impacted by works on the
Site boundary wall, including cleaning and re-pointing and works associated
with the construction of new entrances towards the centre and south. During construction, the magnitude
of change before mitigation is large.
Since this group has low sensitivity, the visual impact is moderate.
During operation, either the new Old Bailey Wing or the new Arbuthnot
Wing will be clearly visible to VSRs along Chancery
Lane but they will not both be visible at the same time. These structures will dominate the change in
view for this VSR group. As described
previously, the new buildings will be compatible with the general high rise
blocks surrounding the Site for this VSR view, as well as being compatible with
the buildings within the Site itself, given the set back from the existing
buildings. The Site boundary wall will
have improved visual amenity due to its cleaning and re-pointing, which will be a positive change for this
VSR, which is right next to it. The retained
buildings will have improved visual amenity through their renovated façades and
which will also be a small positive change for this VSR.
Figure 4.13 illustrates the existing view from this
VP as well as illustrating the proposed view during operation at day 1 with no
mitigation measures in place.
During operation,
the overall magnitude of change before mitigation is large. Since this group has low sensitivity, the visual
impact is moderate.
VPf (VSR T5) – Street Level at Hollywood Road/Pottinger Street Junction:
During the construction, this
group are right next to the Site and being at street level the existing Site
boundary wall will shield these VSRs from the
majority of the construction work being carried out within the Site although
the main entrance will afford them a limited view into the Parade Ground area,
so some of the construction and excavation works here will be visible to
them. Neither of the new buildings will
be visible to them, hence they will not be affected by these construction
works. This group will also be impacted
by the installation of the new, permanent footbridge connecting to the
mid-levels escalator corridor. The main
structure will be constructed off-site and installed ready-made, meaning
duration of disruption will be minimal.
This group will also be able to see other external works along the Site
boundary wall, including those associated with the renovation of the Site wall
and construction of new pavement to the south of
During operation, the Police HQ will have
improved visual amenity through its refurbished façade which will be a positive
change for this VSR. This group of VSRs will not be able to see the new buildings (Old Bailey wing and Arbuthnot wing). The new footbridge will be visible to
them but will not dominate since they have alternative views that do not
incorporate the footbridge. In addition,
the current design of the footbridge, as described in Section 4.5, is open, porous and fairly compatible with the
surrounding view and the quality of the view for these VSRs
will not change much due to the footbridge; it is a small part of their view
and minimally blocks their current view of buildings behind.
Part of Figure
4.9
illustrates the existing view from this VP as well as showing a photomontage of
the view during operation, (although the photomontage has incorporated design
considerations and is not considered totally unmitigated).
During operation,
the overall magnitude of change before mitigation is intermediate
including substantial changes that would be considered beneficial (façade
treatment of existing buildings). This
group has medium sensitivity, and while the matrix described in the methodology
(Section 4.4) gives rise to a moderate adverse visual impact
rating, this assumes all the visual changes are negative. Since some changes, such as that to the
existing Police HQ façade which dominates this VSR groups’ view, are actually
considered positive, and also taking into consideration the travelling nature
of these VSRs and the minimal blocking of their view,
the visual impact is considered to be slight adverse overall.
VSR
During operation, the top of the new Old Bailey Wing building and the new
emergency vehicle access will be visible in the mid to back ground for this VSR
but there will be no other change to their view and they have many alternative
views. As described previously with
regard to the new buildings, the Old Bailey Wing is compatible with the general
high rise blocks surrounding the Site, as well as being compatible with the
buildings within the Site itself, given the set back from the existing
buildings. During operation,
the overall magnitude of change before mitigation is small. Since this group has low sensitivity, the visual
impact is slight.
VSR O1 Medium/High Level Commercial Building(s)
(IFC Building): During construction,
this group are very far away such that although they will be able to see the
construction works within the Site in the background of their view, details of
much of the works will not be apparent.
This VSR will mainly be impacted by the demolition of the Garage,
Workshop & Laundry and General Office buildings, construction of the Old
Bailey Wing and Arbuthnot Wing and their associated hoarding, as well as any
scaffolding erected for the retained building improvement works. Other construction works will not be
distinctly visible. During
construction, the magnitude of change before mitigation is small. Since this group has low sensitivity, the visual
impact is slight.
During operation, the new buildings will be visible in the mid to
back ground for this VSR but the open space of the Parade Ground will still be
visible. As described previously, the
new buildings will be compatible with the general high rise blocks surrounding
the Site as well as being compatible with the Site itself, given the set back
from the existing buildings. The improvement works to the retained buildings
will be apparent but this will not be obvious from this distance. This VSR has
many alternative views and during operation, the overall magnitude
of change before mitigation is small. Since this group has low sensitivity, the visual
impact is slight.
VSR O2 Medium/High Level Commercial Building(s) (
During operation,
the new buildings will be visible in
the mid to back ground for this VSR and be the main change to their view but
they will still be able to see the open space of the Parade ground and they
have many alternative views. As described
previously, the new buildings will be compatible with the general high rise
blocks surrounding the Site as well as being compatible with the Site itself,
given the set back from the existing buildings.
The improvement works to the retained buildings will be apparent but not
obvious from this distance. The magnitude
of change before mitigation is therefore small. Since this group has low sensitivity, the visual
impact is slight.
VSR H1 Medium/High Level Residential Buildings in
Mid-levels (
During operation,
the new buildings will be visible in
the mid to back ground for this VSR and be the main change to their view and
some may no longer be able to see the open space of the Parade ground. As described previously, the new buildings
will be compatible with the general high rise blocks surrounding the Site as
well as being compatible with the Site itself, given the set back from the
existing buildings. The improvement
works to the retained buildings will be apparent but not obvious from this
distance. The magnitude of
change before mitigation is therefore intermediate. Since this group has medium sensitivity, the visual
impact is moderate.
VSR R1 Open/Park Area off
During operation,
the top of the new Old Bailey Wing
building will be partially visible for this VSR but there will be no other
change to their view. As described
previously with regard to the new buildings, the Old Bailey Wing is compatible
with the general high rise blocks surrounding the Site and visible to this VSR,
but they have no view of other buildings within the Site itself. The magnitude of change before
mitigation is small. Since
this group has low sensitivity, the visual impact is slight.
VSR H3 Medium/High Level Residential Buildings on
During the
construction, this group are very close to the west of the Site and will mainly
be impacted by the demolition of General Office buildings and the construction
of the new Old Bailey Wing and the associated hoarding. Works along the Site west boundary wall,
including the construction of the new emergency vehicle access and cleaning and
improvement works will also be visible.
The construction of the new footbridge will also be visible to some of
the VSRs in this group towards the north, including VSRs in the Proposed Grade 3 historic building at
During operation, the new Old Bailey Wing will be visible and be
the main change in view for this VSR group, particularly towards the south,
with the new footbridge affecting those further north. There are no residencies whose views would be
fully blocked as the visible area directly west of the new building is the
Open/Park Area. The Arbuthnot Wing may
be visible to some of the VSRs in this group at
higher levels, but will be in the mid-ground of their view if so. For the VSRs
in the Proposed Grade 3 historic building at 20 Hollywood Road, the new
footbridge will be visible, but given its current open design (as describe in Section 4.5), this will minimally block
the view of a small number of VSRs in this
group. The retained buildings will be a more prominent part of their
view and have improved visual amenity through their renovated façade. In addition to this, the Site boundary wall
will have been improved and all these features will be beneficial change for
this VSR. During operation, the
overall magnitude of change before mitigation is large but some of these
changes can be considered beneficial (improvement to retained buildings). Since this group has high sensitivity, and
considering the large degree of change due to the new Old Bailey Wing, which is
considered adverse, the visual impact is significant.
Table 4.8 Magnitude
of Impact on VSRs affected by the Project
|
VSR ID* |
VSR Name |
VP ID |
Compatibility & Duration of Impact |
Reversibility of Impact |
Closest Distance between VSR & Source(s) of Impact (m) |
Scale as perceived by VSRs |
Potential Blockage of View (None, Minimal, Partial, Full) |
Magnitude of Change BEFORE Mitigation (Negligible,
Small, Intermediate, Large) |
|||
|
|
|
|
Construction |
Operation |
Construction |
Operation |
|
|
|
Construction |
Operation |
|
T2 |
Central/ Mid-Levels
Escalator above |
VPa |
Fairly compatible and
temporary* |
Fairly compatible and
permanent |
Reversible* |
Permanent |
0 |
Large |
Partial |
Large |
Large |
|
H/O 1 |
Medium/High Level
Commercial/Residential Building(s) above |
VPb |
Mixed compatibility and
temporary* |
Mixed compatibility and
permanent |
Reversible* |
Permanent |
10 |
Large |
Minimal |
Large |
Intermediate |
|
T3 |
Street Level at The Centrium on |
VPc |
Mixed compatibility and
temporary* |
Mixed compatibility and
permanent |
Reversible* |
Permanent |
0 |
Large |
Partial |
Large |
Large |
|
H2 |
Medium/High Rise Level
Residential Building(s) on |
VPd |
Mixed compatibility and
temporary* |
Mixed compatibility and
permanent |
Reversible* |
Permanent |
7 |
Large |
Partial/ Full |
Large |
Large |
|
T4 |
Street Level at |
VPe |
Mixed compatibility and
temporary |
Mixed compatibility and
permanent |
Reversible |
Permanent |
0 |
Large |
Partial |
Large |
Large |
|
T5 |
Street Level at |
VPf |
Fairly compatible and
temporary |
Fairly compatible and
permanent |
Reversible |
Permanent |
0 |
Large |
Minimal |
Large |
Large |
|
T1 |
Street Level at |
n/a |
Mixed compatibility and
temporary |
Mixed compatibility and
permanent |
Reversible |
Permanent |
175 |
Medium |
Minimal |
Small |
Small |
|
O1 |
Medium/High Level Commercial
Building(s) ( |
n/a |
Mixed compatibility and
temporary* |
Mixed compatibility and
permanent |
Reversible* |
Permanent |
425 |
Small |
None |
Small |
Small |
|
O2 |
Medium/High Level Commercial
Building(s) ( |
n/a |
Mixed compatibility and
temporary* |
Mixed compatibility and
permanent |
Reversible* |
Permanent |
184 |
Medium |
None |
Small |
Small |
|
H1 |
Medium/High Level
Residential Buildings in Mid-levels ( |
n/a |
Mixed compatibility and
temporary* |
Mixed compatibility and permanent |
Reversible* |
Permanent |
174 |
Medium |
None |
Intermediate |
Intermediate |
|
R1 |
Open/Park Area off |
n/a |
Mixed compatibility and
temporary |
Mixed compatibility and
permanent |
Reversible |
Permanent |
16 |
Medium |
Minimal |
Intermediate |
Intermediate |
|
H3 |
Medium/High Level
Residential Buildings on |
n/a |
Mixed compatibility and
temporary |
Mixed compatibility and
permanent |
Reversible |
Permanent |
11 |
Large |
Partial |
Large |
Large |
*The demolition of the Garage, Workshop
& Laundry and/or General Office (Buildings 5, 16 and 18) may be partly
visible to these VSRs and will be permanent and
irreversible during construction phase.
Visual Impact Upon
Mitigation
The selection of Scheme B for the Project
and proposed design of the two new buildings and the new footbridge have been
discussed in Section 4.5 and Section 2 and the proposed mitigation
measures to mitigate for the impacts of the Project are detailed in Section 4.7.2. The proposed cast aluminium façade treatment
for the new buildings has been carefully selected as a non-reflective material
to help minimise potential glare interference and also with reference to the
existing masonry block elements on site in terms of scale and proportion, thus
establishing a certain contextual relationship with the existing buildings and
ensuring they are even more compatible.
The potential significances of residual visual impacts during
construction and operation phases, after mitigation, are detailed below and
summarised in Table
4.9.
VPa (VSR T2) – Central/ Mid-Levels Escalator above
Detailed design
features will partially mitigate the operation impact as illustrated in Figure 4.9.
The current footbridge design is open with railings designed to be as
porous as possible, as described in Section
4.5, and has been selected to be in keeping with the overall Project, allow
the least blockage of view and maximum visual continuity to VSRs
given the requirements of having an access point here. Mitigation measures for the footbridge have
been considered as described in Section
4.7.2 and detailed design features will further enhance these features
where possible. In addition to the open
design and the beneficial impacts to the Site boundary wall and retained
building façades, the design features incorporated into the footbridge will
mitigate the visual impact slightly but not sufficiently to rate the visual
impact as ‘slight. Therefore the residual
operation impact on day 1 and at year 10 will remain moderate.
VPb (VSR H/O1) – Medium/ High Level
Commercial/Residential Building(s) above
In addition to
design features, the provision of the newly planted trees in the planting site
in the Parade ground, in-situ tree protection (including the clearly visible T5
in the Parade Ground), and other soft landscape measures including the
partially visible green wall at the south of the Site, will reduce the visual
impact at operation. The
façade treatment of the new building has also been selected as described
previously and will help mitigate visual impacts from glare and by enhancing
compatibility. Figure 4.10 illustrates the existing view from this
VP as well as illustrating the proposed view during operation at day 1 and year
10 with mitigation measures in place in addition to the design features. The residual impact on day 1 is considered to
be reduced slight due to all the measures.
By year 10, the trees in the planting site, green wall and tree T5 will
have matured but while this will further reduce the visual impact, it is not
large enough to change the impact classification, and the residual impact at
year 10 is considered to remain slight.
VPc (VSR T3) – Street Level at The
Centrium on
Detailed design
features will partially mitigate the operation impact as illustrated in Figure 4.11.
The façade treatment of the new building in particular has been selected
as described previously and will help mitigate visual impacts from glare and by
enhancing compatibility. Since VSRs from this group will also be present in this area at
night, Figure 4.14 also
illustrates the new night time view from a VP in this VSR area. Given the beneficial changes at operation
already described before mitigation, the mitigation of the impact from the
building façade will mean the residual operation impact at day 1 and year 10 is moderate.
VPd (VSR H2) – Medium/High Rise Level Residential
Building(s) on
Detailed design
features will partially mitigate the operation impact as illustrated in Figure 4.12.
The façade treatment of the new building in particular has been selected
as described previously and will help mitigate visual impacts from glare and by
enhancing compatibility. The in-situ
protection of the trees continued on from the construction phase into operation, will also ensure the small green element of these
VSRs view of the Site is retained and even slightly
enhanced as the trees in the Prison Yard continue increase in height with
maturity. Given the beneficial changes
at operation already described before mitigation, these mitigation measures,
particularly of the impact from the building façades, will mean the residual
operation impact at day 1 and year 10 is moderate.
VPe (VSR T4) – Street Level at
Detailed design
features will partially mitigate the operation impact as illustrated in Figure 4.13.
The façade treatment of the new building in particular has been selected
as described previously and will help mitigate visual impacts from glare and by
enhancing compatibility. In addition to
the beneficial changes to the Site boundary wall and retained building façades
described before mitigation, this mitigation of the impact from the building
façades will mean the residual operation impact at day 1 and year 10 is slight.
VPf (VSR T5) – Street Level at
Design features
of the new footbridge will minimise its visual impact before mitigation as
illustrated in Figure 4.9.
Detailed design considerations will ensure the footbridge design retains
the current concept of being as open and as porous as possible, as described in
Section 4.5, and is in keeping with
the overall Project, causing the least blockage of view and maximum visual
continuity to VSRs given the requirements of having
an access point here. In addition, this
VSR will have a limited view of the new planting site in the Parade Ground,
which will minimally enhance their view of the Site in addition to the
beneficial impacts of the building façade treatment. The residual operation impact at day 1 is
considered to be slight. At year 10 the new trees in the planting area will be larger, but this is a small
part of this VSR groups view and the residual impact will remain slight.
VSR
Detail design
features will partially mitigate the operation impact. The façade treatment of the new building in
particular has been selected as described previously and will help mitigate
visual impacts from glare and by enhancing compatibility. Despite this, the residual operation
impact cannot be considered insignificant as the structures will still be
visible, and therefore remains slight at day 1 and year 10.
VSR O1 Medium/High Level Commercial Building(s) (
Detailed design
features will partially mitigate the operation impact. The façade treatment of the new building in
particular has been selected as described previously and will help mitigate
visual impacts from glare and by enhancing compatibility. The in-situ tree protection, compensatory
planting and soft landscape maintenance mitigation measures will also slightly
increase the Site’s visual amenity value to this VSR along with the retained
building façade improvement works. Given
the large distance (> 400 m) of these VSRs from
the Site, the new buildings, which will be the main cause of visual impact at
this stage, are relatively small in the wider scale of the urban view of these VSRs. With the
façade mitigation measures and ongoing maintenance of the Site, and considering
the sensitivity of these VSRs is low, the residual
operation impact is therefore considered insignificant at day 1 and year 10.
VSR O2 Medium/High Level Commercial Building(s) (
Detailed design
features will partially mitigate the operation impact. The façade treatment of the new building in
particular has been selected as described previously and will help mitigate
visual impacts from glare and by enhancing compatibility. The in-situ tree protection, compensatory
planting, vertical greening and soft landscape maintenance mitigation measures
will also slightly increase the Site’s visual amenity value, along with the
retained building façade improvement works.
Despite this, the residual operation impact cannot be considered
insignificant as the VSRs are close enough for the
structures to still be apparent, and therefore remains slight at day 1 and
year 10.
VSR H1 Medium/High Level Residential Buildings in
Mid-levels (
Detailed design
features will partially mitigate the operation impact. The façade treatment of the new building in
particular has been selected as described previously and will help mitigate
visual impacts from glare and by enhancing compatibility. The retained building façade improvement
works will also slightly increase the Site’s visual amenity value to this
VSR. The in-situ tree protection,
compensatory planting and soft landscape mitigation measures will only be
visible to some VSRs in this group, but will improve the
visual amenity value of the Site for them.
Therefore, the residual operation impact will be reduced to slight
at day 1 and year 10.
VSR R1 Open/Park Area off
Detailed design
features will partially mitigate the operation impact. The façade treatment of the new building in
particular has been selected as described previously and will help mitigate
visual impacts from glare and by enhancing compatibility. Since the existing view will hardly change at
all with only a very small part of the top of the Old Bailey Wing visible (as
described in ‘impact before mitigation’), and due to the façade causing minimal
glare and therefore being less noticeable, the residual operation impact
can be considered to be reduced to insignificant at day 1 and year 10.
VSR H3 Medium/High Level Residential Buildings on
The impact on
this VSR/ VP without mitigation is significant during construction and
operation. Construction is assumed to be
carried out following standard good practise, and the construction impact will
not be significantly reduced by additional mitigation measures so the residual
construction impact will remain significant.
Detailed design
features will partially mitigate the operation impact. The façade treatment of the new buildings in
particular has been selected as described previously and will help mitigate
visual impacts from glare and by enhancing compatibility in particular for
those VSRs towards the south of the VSR group, for
whom the new Old Bailey Wing will be a more prominent part of their view. For those VSRs with
a clearer view into the Site, ie at higher levels,
the provision of the newly planted
trees in the planting site in the Parade ground, in-situ tree protection and
other soft landscape measures, may help to reduce the
visual impact at operation. For
the VSRs able to see the new footbridge, in
particular those in the Proposed Grade 3 historic building at 20 Hollywood
Road, the new footbridge will be visible, but detailed design considerations
will ensure its design (as described in Section
4.5) will block the view as little as possible and only a small number of VSRs will be partially affected.
In addition to the beneficial impacts to
building façades and boundary wall already described before mitigation, and
considering the main adverse impact is from the new building, these mitigation
measures will mean the residual operation impact at day 1 and year 10 is reduced to moderate.
Table 4.9 Significance
of Visual Impacts in Construction and Operation Phases, before and upon
Mitigation
|
VSR ID* |
VSR Name |
VP ID |
Receptor Sensitivity (Low, Medium, High) |
Magnitude of
Impact BEFORE Mitigation (Negligible, Small, Intermediate, Large) |
Impact
Significance BEFORE Mitigation (Insignificant, Slight, Moderate, Significant) |
Recommended Mitigation Measures |
Residual Impact
Significance UPON Mitigation (Insignificant, Slight, Moderate, Significant) |
||||
|
|
|
|
|
Construction |
Operation |
Construction |
Operation |
|
Construction |
Operation Day 1 |
Operation Year
10 |
|
T2 |
Central/ Mid-Levels Escalator above |
VPa |
Medium |
Large |
Large |
Significant |
Moderate |
M1, CM5, OM3, OM4 |
Significant |
Moderate |
Moderate |
|
H/O 1 |
Medium/High Level Commercial/Residential Building(s)
above |
VPb |
Medium |
Large |
Intermediate |
Significant |
Moderate |
M1, CM1-7, OM1-4 |
Significant |
Slight |
Slight |
|
T3 |
Street Level at The Centrium
on |
VPc |
Medium |
Large |
Large |
Significant |
Significant |
M1, CM5, OM1-5 |
Significant |
Moderate |
Moderate |
|
H2 |
Medium/High Rise Level Residential Building(s) on |
VPd |
High |
Large |
Large |
Significant |
Significant |
M1, CM1-5, OM1-M4 |
Significant |
Moderate |
Moderate |
|
T4 |
Street Level at |
VPe |
Low |
Large |
Large |
Moderate |
Moderate |
M1, CM5, OM3,
OM4 |
Moderate |
Slight |
Slight |
|
T5 |
Street Level at |
VPf |
Medium |
Large |
Intermediate |
Significant |
Slight† |
M1, CM1-7, OM1-4 |
Significant |
Slight |
Slight |
|
T1 |
Street Level at |
n/a |
Low |
Small |
Small |
Slight |
Slight |
M1, CM5, OM3,
OM4 |
Slight |
Slight |
Slight |
|
O1 |
Medium/High
Level Commercial Building(s) ( |
n/a |
Low |
Small |
Small |
Slight |
Slight |
M1, CM1-7, OM1-4 |
Slight |
Slight |
Slight |
|
O2 |
Medium/High
Level Commercial Building(s) ( |
n/a |
Low |
Small |
Small |
Slight |
Slight |
M1, CM1-7, OM1-4 |
Slight |
Insignificant |
Insignificant |
|
H1 |
Medium/High
Level Residential Buildings in Mid-levels ( |
n/a |
Medium |
Intermediate |
Intermediate |
Moderate |
Moderate |
M1, CM1-7, OM1-4 |
Moderate |
Slight |
Slight |
|
R1 |
Open/Park Area
off |
n/a |
Low |
Intermediate |
Intermediate |
Slight |
Slight |
M1, CM5, OM3,
OM4 |
Slight |
Insignificant |
Insignificant |
|
H3 |
Medium/High
Level Residential Buildings on |
n/a |
High |
Large |
Large |
Significant |
Significant |
M1, CM5, OM3,
OM4 |
Significant |
Moderate |
Moderate |
|
* T-Travelling ; H-Residential ; O-Occupational
; H/O-Mixed Residential/Occupational ; R- Recreational † Since much of the change in the
‘intermediate’ magnitude of change for this VSR is considered beneficial, the
overall adverse impact significance is lower than the matrix in the
methodology implies, since the methodology assumes all the change is adverse.
|
|||||||||||
Glare Impact
In terms of potential glare interference,
the extent of impact depends on the mass of the building, the choice of façade
material to be chosen and the lighting arrangement at the building. The scheme for the Project has been selected
considering glare impacts, as detailed in Section
2. The design intention for the new
buildings is to use non-reflective material for the façade which will help to
minimise potential glare interference.
Different façade treatments have been
considered for the new building, taking into account their potential to pose
glare impact. A fully glazed façade was
rejected partially due to the potential to pose glare impact and a polished
aluminium metal panel façade was also rejected over the potential for glare
impact. A cast aluminium unitized façade
system has been considered suitable for the new building, having done studies
of existing site material textures and scales, such as porous masonry,
traditional brick and granite wall constructions (see Figure
2.5). The versatility of aluminium in terms of
texture, malleability, light weight, lifecycle and general aesthetic makes it
the preferred material for the distinctive integration of new construction
within the historical heritage compound.
As opposed to a material like stainless steel where the finish is
usually highly reflective, the materiality of the cast aluminium units will
have a distinctive roughness and texture.
Together with their materiality, the unit blocks also serve to break
down the façade surface adding to the reduction of reflectivity and glare,
especially important during the daytime.
At night, light emitted from the building
will be partially screened by the façade units, creating a balance between
being able to express the life of the buildings within while also being able to
reduce light pollution. The most open
area within the new buildings at night is the public restaurant which is
located on the north end of Old Bailey Wing and away from the row of residential
buildings directly to the south. All
lights within the CPS will be turned to night time mode (dimmed) after
11pm.
With respect to external façade lighting,
the historic buildings would not traditionally have been lit artificially since
electric lighting was a new technology in the early 20th century and its
application would have been devoted first to those areas previously lit by
other means, that is, interiors. Even by
the time of the site’s decommissioning, the extent of external lighting was
limited to wayfinding and the illumination of spaces,
not the illumination of buildings. Such
light that fell upon the exteriors of buildings was incidental. Any new external lighting scheme would therefore
seek to replicate this condition and be deliberately understated and currently
there are no plans to illuminate the buildings within the Site with external
lighting.
Figure 4.14 illustrates comparative day and night
time views towards the new Old Bailey Wing and Arbuthnot Wing.
Given the choice of façade treatment and
Site lighting considerations, the glare impact from the Project is considered
to be acceptable.
Cumulative impacts refer to any concurrent projects
within the Study Area in conjunction with the Project giving rise to a
cumulative impact on the existing LRs/LCAs or
VSR.
The former Police Married Quarters on
In terms of cumulative landscape impacts, the former
Police Married Quarters site falls upon LR2 (Commercial/ Residential/
Institutional Building Area) which is not affected by
this Project. It is also unlikely to
have a cumulative impact on Residential/ Commercial Urban Landscape (LCA4)
since this Project has only a slight impact on this LCA during construction,
but insignificant impact during operation.
In terms of cumulative visual impact, neither site is visible to each
other (see Figure 4.6), so
cumulative visual impacts are unlikely.
Therefore it is unlikely that there will by any cumulative impacts due
to these projects running concurrently.
Monthly inspections of affected trees by an
experienced and appropriately trained arborist or
horticulturist using Form 1 – Tree Group Inspection Form and Form 2 – Tree Risk
Assessment Form developed by Development Bureau (http://www.trees.gov.hk/en/doc/TRAGuideline_July2010version_combine.pdf)
or a form designed by a tree expert and approved by Tree Management
Office. All irregularities that deviate
from the recommended tree protection measures, or could impose deleterious
impacts on the protected trees, must be reported to the authorized person or
the tree expert within two days.
A detailed specifications and methods statement could
be drafted and included in the soft landscape maintenance contract to
circumscribe the scope and to ascertain the quality of the work. Following this, quarterly inspections of
affected and newly planted trees should be undertaken by an experienced and
appropriately trained arborist or horticulturist for
a period of 12 months. Hard landscape
maintenance will be covered by the Conservation Management Plan and Operational
Phase Manual, as detailed in Sections
3.7.1 and 3.7.4.
The general design philosophy and choice of the
design scheme are explained in Section
4.5 and this LVIA has been prepared for Design Scheme B in accordance with
the requirements of the EIA Study Brief, Annexes
10 and 18 of the EIAO-TM and the EIAO Guidance Note No. 8/2002 “Preparation of
Landscape and Visual Impact Assessment under the Environmental Impact
Assessment Ordinance.”
A baseline study was conducted and nine LRs, seven LCAs, and 12 VSRs representing four VSR categories were identified and
their sensitivity/quality assessed. The
impact on these LRs/LCAs and VSRs
was assessed and measures suggested to mitigate the impacts. Further explanation of the limitations in
applying certain mitigation measures are set out in Section 4.7.2.
This landscape impact assessment shows that six of
the LRs and five of the LCAs
in the Study Area would not be impacted by the Project, revealing it is a
relatively contained project. The
unaffected LRs/LCAs are LR2 (Commercial/ Residential/
Institutional Building Area), LR5 (
The impacted LRs/LCAs are
LR1 (
·
significant for LR3 (Buildings within
·
slight for LR1 (
The impacts of the Project’s operation phase before mitigation
on these LRs/LCAs are:
·
not
considered significant for any LR/LCA;
·
moderate
for LR3 (Buildings within
·
insignificant for LR1 (
Upon implementation of measures proposed in the Project to mitigate
the construction impact, residual impacts:
·
for
LR3 (Buildings within
·
will remain slight for (
In addition to construction phase mitigation
measures, upon implementation of further measures to mitigate operation
impact, residual impacts:
·
for LR3 (Buildings within
·
will
have been enhanced for LR4 (Open Space within
·
will remain insignificant for LR1 (
During the construction phase, before mitigation:
·
T2-VPa
(Central/Mid-levels Escalator above Hollywood Road), H/O 1-VPb (Medium/High
Level Commercial/Residential Building(s) above Holly wood Road), T3-VPc (Street
Level at the Centrium on Arbuthnot Road), H2-VPd
(Medium/High rise Level residential Building(s) on Chancery Lane), T5-VPf
(Street Level at Hollywood Road/Pottinger Street
Junction) and H3 (Medium/High Level Residential Buildings on Old Bailey Street)
will receive significant visual impacts;
·
T4-VPe
(Street Level at Old Bailey Street/Chancery Land Junction), H1 (Medium/High
Level Residential Commercial Building(s) in Mid-levels [Grand Panorama]) will
receive moderate visual impacts; and
·
T1
(Street Level at
Construction is assumed to
be carried out following standard good practise, and the construction impact
will not be significantly reduced by additional mitigation measures such that upon mitigation, all the impacts are considered to remain
the same.
During operation phase, before mitigation:
·
T3-VPc(Street
Level at the Centrium on
·
T2-VPa
(Central/Mid-levels Escalator above
·
T1
(Street Level at
Upon implementation of mitigation measures, at
operation day 1 the
visual impacts on:
·
T3-VPb,
H2-VPd and H3 will reduce to moderate while that for T2-VPa will remain
moderate.
·
H/O1-VPb,
T4-VPe and H1 will reduce to slight while impacts on T5-VPf, T1 and O2
will remain slight.
·
O1
and R1 will reduce to insignificant.
At operation year 10 with mitigation, the residual impacts remain the same for
all the VSRs.
The Project and particularly the building of the new
structures (Old Bailey Wing, Arbuthnot Wing, new
footbridge) will produce some adverse landscape and visual impacts but these can
be eliminated, reduced or offset to a large extent by clever design and
mitigation measures. The massing and
style of the new buildings is dictated by the zoning envelope and height
restriction set for potential new buildings under the OZP, the internal space
(floor area and ceiling height) required to achieve the proposed uses and the
well-established concept in conservation that new interventions, whether
internal alterations in an historical building or whole new buildings on an
historical site, should be “of their time” ie
modern. The design of new buildings
takes the approach to set back from the maximum building envelope so as to
minimise disturbance to the adjacent historic buildings and leave them intact. The proposed cast aluminium façade treatment
has also been carefully selected as a non-reflective material to help minimise
potential glare interference and also with reference to the existing masonry
block elements on site in terms of scale and proportion, thus establishing a
certain contextual relationship with the existing buildings. Hence, in terms of the massing of the
buildings and style, they are compatible in terms of both a visual (and
cultural heritage) perspective. The
modestly dimensioned new buildings will also enrich the CPS immeasurably by
providing added flexibility, function and cultural use to the site while
preserving the existing heritage buildings and making them accessible to the
public.
There will be some beneficial landscape and visual
impacts from the renovation and refurbishment of the existing buildings and
open spaces within the Site and along the Site boundary wall, the addition of a
new green wall and planting site and protection and enhancement of the existing
soft landscape. All adverse landscape
impacts are reduced to slight-insignificant by year 10, with the impact on the
open space with the declared monument (LR4) being slightly beneficial. All adverse visual impacts are reduced to
moderate to insignificant by day 1 of operation (and remain the same at year 10).
Therefore according to Annex 10 of the EIAO-TM,
the potential Landscape and Visual Impacts due to the construction and
operation of the Project are considered acceptable with mitigation.
Generally to all the retained buildings:
· All existing signage painted directly to the external walls
will be preserved.
· All painted render elevations will be repaired and
repainted.
· All barbed wire and security screens attached to buildings
will generally be removed. Some barred
gates will be retained and preserved for interpretation.
· All existing services fixed to the elevations, including
electrical cables and conduits and miscellaneous pipework no longer required,
will be removed and the surfaces made good.
· All brickwork and stonework to the elevations will be
repaired.
· All roofs will be repaired where necessary. Pitched tiled roofs will be retiled where
necessary. Flat concrete roofs will be
recovered.
· All exposed rainwater gutters and downpipes will be
retained and refurbished, or replaced with new matching rainwater goods.
· All windows will be repaired, replaced or overhauled.