12
CUMULATIVE IMPACTS ASSESSMENT
12.2.1
This EIA has considered the construction and operational phase
cumulative impacts resulting from the proposed implementation of other
developments within the study area.
There is only one key interface with the proposed improvement to Tung
Chung Road, situated at the northern end of its alignment, namely the proposed
Development in Tung Chung and Tai Ho.
12.2.2
The development in Tung Chung and Tai Ho is being assessed under the
Remaining Development in Tung Chung and Tai Ho Comprehensive Feasibility Study
(CFS) currently being conducted by the Territory Development Department
(TDD). The development proposals of
relevance to this study involve the construction of residential properties and
associated educational facilities in Tung Chung Valley. The cumulative
assessment has been based upon reference to the Remaining Development in Tung
Chung and Tai Ho Comprehensive Feasibility Study, Environmental Studies Final
Assessment Report, March 2000 (the CFS Report), the Tung Chung Valley Concept Plan, July 2001 and the North Lantau
New Town Phase IIB (Part) Layout Plan, number L/I-TCIIB/1C.
12.2.3
The assessment of cumulative impacts includes air quality, noise, water
quality, waste, ecological factors and
landscape and visual impacts during both the construction and operational
phases as appropriate.
12.1.1.1 In accordance with the latest information
provided from TDD and Planning Department, site formation in the Tung Chung
Valley will commence in 2005.
12.1.1.2 In comparison, the construction of the
improved Tung Chung Road, in accordance with the proposed programme presented
in Section 2 of this EIA report, will commence in mid 2004, with a view to
opening the road link in late 2006.
Based upon these dates, there is the potential for construction phase
cumulative impacts to the existing village sensitive receivers in Tung Chung
Valley, with the future residential development being still under construction
upon the operation of the improved Tung Chung Road. Existing sensitive receivers in Tung Chung Valley are listed as
the Ngau Au, Mok Ka and Shek Mun Kap villages in the CFS Report, as detailed in
Section 4 of this report.
12.1.1.3 The construction air quality assessment
detailed in Section 4 of this report has concluded that the two of the closest
properties in this area which are adjacent to the road, designated SR2 and SR4,
will require mitigation measures to reduce dust levels to within the standards
as a result of the construction of the project. The CFS Report has also recorded that dust levels overall will
exceed the 1 hour or 24 hour standards during Phase 3 and 4 developments, if
mitigation is not implemented. The
report concludes that, with the application of a combination of mitigation
measures including site watering and assuming that only 40% of the site will be
actively worked at any one time, dust levels at the sensitive receivers will be
reduced to well below the dust criteria. The mitigation measures recommended in
the CFS Report concur with those in Section 4 of this report.
12.1.1.4 As the majority of the dust generating
activities in the form of site formation works will be undertaken by the Tung
Chung development, with much of the work for the improved Tung Chung Road being
of a much smaller scale in this area and less dust generating, cumulative
impacts are considered to be limited.
In addition, based upon the conclusion of the CFS that dust
concentrations can be further reduced, it can be concluded that any cumulative
impacts can be properly mitigated with the application of the mitigation
measures recommended by the two studies.
No residual impacts are predicted.
12.2.2.1
In
accordance with the latest programming information from TDD, occupation of the
development will be in 2010 and as such the residential blocks and schools will
represent sensitive receivers to operational traffic pollutants from the Tung
Chung Valley development itself and the improved Tung Chung Road.
12.2.2.2
Assessment
of operational air quality by the CFS comprised nitrogen dioxide and respirable
suspended particulates (RSP) for the year of 2011. However, the improved Tung Chung Road project was not included in
the operational assessment scenario investigated by the CFS. Thus, operational
air quality modelling at representative sensitive receivers, within 500m of the
improved Tung Chung Road as shown in Figure 12.1a, for the worst case year for
vehicular emissions of 2021 has been undertaken. The layout of these areas is
not known at this time and as such assumed representative locations on the site
boundaries have been assumed for the purposes of the assessment. The exception to this is the secondary
schools in Area 40 as shown on the Architectural Services Department, Master
Site Layout Plan, number AB/6431/MGP001a, shown in Figure 12.1b. The modelling
has been undertaken based upon the methodology detailed in Section 4 of this
report and scenarios for both with and without noise mitigation have been
assessed. In order to simulate the affect of the proposed noise barriers (see
Section 5) on pollutant dispersion, it is assumed that vertical barriers would
effectively change the emission source height to a level which equals to the
height of the barrier.
12.2.2.3
The
predicted vehicular emissions at each of the ASRs has been superimposed
upon the background air quality data to
predict the total air impacts. The
results for the emission factors nitrogen dioxide and RSP, are shown in Tables
12.1 and 12.2 and pollution contours are shown in Figures 12.2 and 12.3 for NO2
and RSP respectively. A full set of
modelling results are provided in Appendix L.
The results show that all parameters, both with and without the noise
mitigation measures recommended in Section 12.3 below applied, comply with the
relevant AQOs. Thus, no residual cumulative
impacts are predicted.
Table 12.1 1-hour and 24-hour maximum RSP and NO2 concentrations (µg/m3) at ASRs (including background level) (without noise mitigation)
|
Receiver Reference |
NO2(µg/m3) |
RSP(µg/m3) |
||
|
1-hour (criteria 300 µg/m3) |
24-hour (criteria 150 µg/m3) |
1-hour |
24-hour (criteria 180 µg/m3) |
|
|
R1 |
62 |
53 |
57 |
55 |
|
R2 |
51 |
46 |
54 |
53 |
|
R3 |
51 |
46 |
54 |
53 |
|
R4 |
55 |
49 |
55 |
53 |
|
R5 |
51 |
46 |
54 |
53 |
|
R6 |
57 |
50 |
56 |
54 |
|
S1 |
65 |
55 |
58 |
55 |
|
S2 |
62 |
53 |
56 |
54 |
|
S3 |
58 |
51 |
55 |
54 |
|
S4 |
53 |
47 |
55 |
53 |
|
P1 |
86 |
67 |
64 |
59 |
Table 12.2 1-hour and 24-hour maximum
RSP and NO2 concentrations (µg/m3) at ASRs (including
background level) (with noise mitigation)*
|
Receiver Reference |
NO2(µg/m3) |
RSP(µg/m3) |
||
|
1-hour (criteria 300 µg/m3) |
24-hour (criteria 150 µg/m3) |
1-hour |
24-hour (criteria 180 µg/m3) |
|
|
R1 |
70 |
58 |
60 |
56 |
|
R2 |
57 |
50 |
56 |
54 |
|
R3 |
56 |
49 |
56 |
54 |
|
R4 |
61 |
52 |
57 |
55 |
|
R5 |
56 |
49 |
56 |
54 |
|
R6 |
60 |
52 |
57 |
55 |
|
S1 |
77 |
62 |
62 |
58 |
|
S2 |
69 |
57 |
60 |
56 |
|
S3 |
64 |
54 |
58 |
55 |
|
S4 |
59 |
51 |
57 |
54 |
|
P1 |
88 |
69 |
65 |
59 |
* Note: The
air quality modelling has assumed barriers will be in place between Lung Tseng
Tau and Ha Ling Pei. Section 5 of this
EIA, however, recommends barriers in Lung Tseng Tau only. The longer length of barrier used for air
quality modelling purposes will provide a conservative assessment and in
reality the levels will be lower.
12.3.1.1 As detailed above in Section 12.2.1.1,
current programming of the two studies suggests that construction will be
on-going concurrently and thus, potential construction phase cumulative noise
impacts will be restricted to the existing village sensitive receivers in the
Tung Chung Valley, with the future residential developments being still under
construction upon the operation of the improved Tung Chung Road.
12.3.1.2 The construction noise assessment for the
improved Tung Chung Road, as detailed in Section 5 of this report, has
predicted the noise impacts on two existing village properties adjacent to the
road, designated SR2 and SR4 and shown in Figure 5.1a, during road
construction. However, the noise can be adequately controlled to 75 dB(A) or
less with suitable mitigation. The CFS
has predicted that construction noise levels will not exceed the standards in
the Tung Chung Valley.
12.3.1.3 One of the closest existing sensitive
receivers to construction activities of both the proposed improved Tung Chung
Road and the development in Tung Chung Valley is a village house in Wong Ka
Wai, designated SR2 by this EIA, as shown in Figure 5.1a. The works associated with the Tung Chung
Valley development will be about 200m away from this sensitive receiver. The worst case unmitigated noise from Tung
Chung Road at this NSR is predicted to be 87 dB(A) during the permanent noise
barrier construction. The worst case activities for the Tung Chung Valley
development are road construction at 122.4 dB(A) and site development at 121.4
dB(A), as detailed in Tables 3.6 and 3.7 of the CFS Report. Based upon these
scenarios and a distance of approximately 200m from the works, the worst case
unmitigated noise from the Tung Chung Valley development would be about 71dB(A)
(122.4 dB(A) minus 54dB(A) for distance attenuation plus 3 dB(A) for the facade
effect) during road construction and 70 dB(A) for site formation. Thus, the cumulative unmitigated noise level
at SR2 assuming these worst case activities would be on-going simultaneously
would remain 87 dB(A) in both cases.
12.3.1.4 Based upon the use of quiet plant, the
CFS reports records a mitigated level of 68 dB(A) (118.7 dB(A) minus 54dB(A)
for distance attenuation plus 3 dB(A) for the facade effect) for road
construction and 65.4 dB(A) (118.7 dB(A) minus 54dB(A) for distance attenuation
plus 3 dB(A) for the facade effect) for site development. Mitigation measures specified by this EIA
will reduce noise levels to 75 dB(A).
When added to the predicted Tung Chung Valley development road
construction noise, the cumulative level will be 76 dB(A) and for the Tung
Chung Valley site development the cumulative level would be 75.5 dB(A) Thus, in both cases noise levels at the
sensitive receiver will marginally exceed the relevant noise criteria as a
result of works going on simultaneously.
However, The CFS report also recommends construction activities should
be planned so that parallel operations close to a receiver is avoided. Thus, cumulative impacts can be avoided by
scheduling permanent noise barrier construction in Tung Chung at times when the
mobile crane and road planer for the CFS road works and the mobile crane during
site development works are not operational.
Cumulative noise levels would remain at 75dB(A) if this is undertaken.
12.3.1.5 During road construction for the Tung
Chung Road, the unmitigated noise from the Tung Chung Road improvement works at
SR2 is predicted to be 79 dB(A) during road works. Thus, the cumulative
unmitigated noise level at SR2 assuming these worst case activities would be
on-going simultaneously with the Tung Chung Valley development, would increase
slightly to 79.5 dB(A). Mitigation
measures specified by this EIA will reduce noise levels to 72 dB(A). When added to the predicted Tung Chung
Valley development mitigated noise level of 68dB(A), the cumulative level will
be 73.5 dB(A) which is within the noise limit.
Thus, no adverse residual cumulative impacts are predicted. In addition, no adverse cumulative impacts
would occur if Tung Chung Road road works and Tung Chung Valley site
development works were on-going simultaneously.
12.3.2 Operational Phase
12.3.2.1 The proposed residential blocks and schools in Tung Chung Valley will represent sensitive receivers to operational traffic noise from both the development itself and the improved Tung Chung Road. The layout of this area (Figure 12.1a) has not been determined, with the exception of the schools in Area 40 as shown on the Architectural Services Department Master Site Layout Plan, number AB/6431/MGP001a (Figure 12.1b). However, the CFS previously adopted a stepped approach to the development of mitigation measures to protect sensitive receivers including applying a maximum setback to sensitive development, strategic positioning of non-sensitive screening buildings, orientation of building and use of podiums, with physical barriers being the last resort and landscaped bunds being preferred to structural barriers. It is anticipated that this approach would be followed for the layout design of the Tung Chung Valley.
12.3.2.2 The CFS has undertaken operational noise
modelling based upon 2011 morning peak predicted traffic flows for existing and
future roads, excluding the local roads. The CFS Report does not predict any
impacts in Tung Chung Valley with values of 66 dB(A) being predicted at schools
in Area 40. However, the modelling did
not include the local distributor roads, nor did it take into account the
improved Tung Chung Road project.
12.3.2.3 Thus, in order to further assess the
cumulative impacts on the existing and future residents in the Tung Chung
Valley, the operational noise levels at representative sensitive receivers, as
shown in Figure 12.1a and 12.1b, for the improved Tung Chung Road worst case
year of 2021, has been undertaken. Sensitive
receivers R2, R3 and R5 will be screened from noise from Tung Chung Road by the
builsings in front of them and as such are not assessed further. The traffic
figures used for the assessment have been are detailed in Section 2 of this
report. The following assumptions have
been made in undertaking this assessment:
¨ secondary schools in Area 40 are 7 storeys in height. All other schools are assumed 6 storeys high (assumed sensitive facades denoted by prefix “S” in Figure 12.1a and Figure 12.1b);
¨ only the top 3 floors of S2b has been modelled and the 5 storey annex of the school in front which is not sensitive to noise provides screening (Figure 12.1b);
¨ residential developments R3 and R4 and village areas are 3 storeys in height (assumed sensitive facades denoted by prefix “R” in Figure 12.1);
¨ local distributor roads as detailed in Section 2 of this report have been included;
¨ noise barriers recommended by this EIA (Section 5) have been included;
¨ sensitive receiver locations have been located on the closest boundary of the development units to Tung Chung Road for the purposes of modelling;
¨ the receiver is assumed to face the improved Tung Chung Road;
¨ the angle of view of all sensitive receivers is 1800; and
¨ screening and reflection of the buildings has been taken into account.
12.3.2.4 The operation noise modelling results are provided in Appendix L. The results indicate that the noise levels at the majority of NSRs are within the relevant criteria. However, for the school development, the maximum noise levels at the sensitive receivers S1 and S4 are 70.9dB(A) and 71.9dB(A) respectively. These levels exceed the noise criteria for schools of 65dB(A).
12.3.2.5 The exceedance at the sensitive receiver S4 implies that the noise level at proposed schools in Areas 44 and 99 will also exceed the 65 dB(A) noise criteria.
12.3.2.6 However, the results show that the adverse noise impacts at S4 are a result of noise from the future local distributor road network, particularly Road L7 which is shown in Figure 12.2 and also in Figure 2.19. The noise contribution from the improved Tung Chung Road is not significant and mitigation measures to protect the properties from Tung Chung Road would not reduce the overall noise levels experienced by these sensitive receivers.
12.3.2.7 In respect of S1, the main noise contribution is from the improved Tung Chung Road and thus, mitigation is required to protect this future receiver from operational noise. A 4m landscaped bund between the school site and the road is proposed and the noise level in Appendix L show that this is sufficient to reduce the levels to within the acceptable 65 dB(A) criteria. The location of the noise bund together with a cross-section is shown in Figure 12.4.
12.4.1.1 Potential water quality issues for the
CFS during the construction phase area are largely associated with site
runoff. The improved Tung Chung Road
project has designed a special pipeline system to collect, transfer and
discharge all runoff into the nullah at Ha Ling Pei and no discharge into the
inland streams will occur. As such, cumulative water quality impacts could
occur on the nullah and Tung Chung Bay, assuming that the CFS discharges
run-off in this location.
12.4.1.2 The CFS states that runoff from the works
areas can be controlled through the use of best practicable construction site
drainage as specified by EPD’s guidelines.
The construction phase runoff for the improved Tung Chung Road will be
collected and treated via sedimentation traps prior to discharge. These measures and those proposed by the CFS
will be sufficient to mitigate any cumulative impacts and unacceptable residual
impacts will not arise.
12.4.2.1 There are no operational phase water
quality issues associated with the development of Tung Chung Valley reported in
the CFS Report. Potential operational
water quality impacts associated with the improved Tung Chung Road are limited
to runoff from the road. However, it is
the intention to collect all runoff and discharge it into the nullah thus
avoiding the sensitive inland streams. Thus, there are not expected to be any
cumulative impacts on water quality.
12.5.1.1 The CFS predicts that construction
activities associated with the development will generate various kinds of waste
including excavated material, chemical wastes and general refuse but in small
quantities. Also, the majority of
material generated during site development is recommended to be reused on site
to form landscaping and planting areas.
As detailed in Section 7 of this report, construction waste generation
from the improved Tung Chung Road will also include these elements and the
on-line section of the improved Tung Chung Road will generate about 21,000m3
of excavated waste. Mitigation measures
recommended by the two studies to manage the storage, handling, transportation
and disposal of the various waste types concur, with material being recommended
for reuse and recycling on site as far as possible. In both cases, unacceptable cumulative impacts are not predicted.
12.5.1.2 Based upon the current programming,
construction activities may be on-going concurrently and thus, it may be
possible to combine and optimise waste storage and collection procedures which
could create a cumulative benefit. In
addition, the surplus material from the Tung Chung Road project may be useful
in reclamation and land formation for the Tung Chung Development.
12.6.1.1 The predicted habitat loss detailed in
the CFS Report for the Tung Chung Valley comprises mainly active or abandoned
agricultural land and some grass/shrubland, with the Fong Yuen Marsh being
preserved as a Conservation Area. A
figure of 38.2ha loss of agricultural land is stated with a moderate impact but
this relates to the Tung Chung region as a whole and therefore the Tung Chung
Valley figure would be much small and the impact less. Loss of grassland and shrubland in the area
is ranked as insignificant by the CFS as they noted that this habitat did not
support a high diversity of flora and fauna.
12.6.1.2 Tung Chung Road is being improved on-line
in this area with works restricted to localised widening on the eastern side of
the existing road. The losses
attributable to these works comprise mainly shrub and tall shrub which have
been assessed as having low-moderate and moderate to high value respectively. However, in the Tung Chung valley losses are
small, with only 0.51ha of shrub and 0.9ha of tall shrub lost. There will also be loss of a negligible
amount of secondary woodland (0.009ha) as a result of the need for the
operational run-off pipeline system.
However, impacts in this area when taken in isolation would be
considered to be minor.
12.6.1.3 Based upon the small amounts lost and the
proposed mitigation in the form of compensatory planting by both studies, no
further mitigation measures are considered to be necessary.
12.6.1.4 In respect of noise and disturbance to wildlife,
the CFS Report identified disturbance from noise and activity associated with
the new town and increased visitors to the countryside as possible agents which
may disrupt the behaviour and breeding patterns of wildlife. These disturbance impacts were ranked as
“insignificant”. The improved Tung
Chung Road will be a restricted access road and consequently traffic flow will
be relatively low and mainly occur during the morning and evening rush hours. Impacts were also judged to be
“insignificant”. Cumulatively, impacts
will remain “insignificant”.
12.7.1.1 The Tung Chung Valley will be subject to
low rise development in the form of schools and residential properties. The CFS has stated that existing visually
sensitive receivers (VSR) will experience visual obstruction as a result of the
proximity of the development and the proposed high levels of density
proposed. However, mitigation in the
form of view corridors, the use of conservation and landscape zones on the
development edge and the low rise nature of the development in the valley are
proposed.
12.7.1.2 The assessment undertaken for the
improved Tung Chung Road identifies the Tung Chung Valley as being of unspoilt
character and sensitive to development.
the assessment, however, takes account of the proposed development both
as a detractor in the landscape, and a location for future visually sensitive
receivers.
12.7.1.3 Construction phase impacts associated
with the improved Tung Chung Road (within the Tung Chung Valley area), would
comprise the loss of mainly scrub vegetation as a result of road widening and
formation of new slopes and the construction of noise barriers and
cycletrack. These are anticipated to
cause slight impacts on landscape resources, but negligible impacts on the
Landscape Character of the Tung Chung Valley as it is assumed that this will
already have been heavily modified by the proposed CFS.
12.7.1.4 The construction works would result in
substantial visual impacts on residents in the villages Lung Tseng Tau / Wong
Ka Wai / Ha Ling Pei / Sheung Ling Pei / Fui Yiu Ha close to the road; with
slight impacts on the villages of Shek Pik Au and Shek Mun Gap higher in the
Valley, and on Ngau Au, Tung Hing, Lam Che, Nim Yuen Villages to the west,
where the intervening, Tung Chung Valley Development would constitute a far
more significant intrusion on their views.
12.7.1.5 During the operational phase, the
architectural treatment of noise barriers, the reinstatement of disturbed
areas, and the greening of previously concreted slopes would help to reduce the
scale of impacts on landscape resources within Tung Chung Valley to slight to
negligible levels by Opening Day, and negligible levels in the long term.
12.7.1.6 Compensatory planting will help to reduce
the visual contrast of the newly formed slopes with surrounding natural hill
slopes, mitigating the impact on views from existing villages, at Lung Tseng
Tau / Wong Ka Wai / Ha Ling Pei / Sheung Ling Pei / Fui Yiu Ha, to intermediate
levels upon completion of the works, and with the growth of screen planting this
would be reduced further in time to a slight level. Visual impacts on the villages of Shek Pik Au and Shek Mun Gap
higher in the Valley, and on Ngau Au, Tung Hing, Lam Che, Nim Yuen Villages on
the west side of Tung Chung Valley, would be reduced to negligible levels by
Opening Day.
12.7.1.7 The two studies would not overlap physically but would have a common landscape and visual setting in the area of the Tung Chung Valley. The impact on views for existing residents in Tung Chung Valley of the improved Tung Chung Road are not likely to be substantive, as the widened section of road will have a similar appearance to the existing road, with the slightly large area of slopes compensated for by the higher proportion of vegetated slope surfaces and with the retained trees screening the carriageway and the traffic. Landscape and visual impacts for these receivers would be dominated by the new CFS development.
12.7.1.8 The cumulative impact on landscape
resources (woodland, topography etc) would be a product of the impacts identified
separately for the two development, taking into account that there would be no
common area of impact.
12.7.1.9 The cumulative impact on landscape
character of the two developments would be a combination of slight-negligible
adverse long term impacts on the character of the Tung Chung Valley from the
improved Tung Chung Road added to the moderate adverse impacts caused by the
development in the valley on existing residential properties. The cumulative impact would be of the same
magnitude but spread over a slightly wider area.
12.8.1.1 Based upon the assessment above, it is
concluded that few cumulative impacts will occur based upon the implementation
of the two projects as there is little direct interface. Sufficient mitigation
measures to reduce most impacts to within acceptable levels have been
recommended for both the CFS and the improvement to Tung Chung Road
project. However, careful scheduling of
works is required during the permanent noise barrier construction for Tung
Chung Road and road and development works for the Tung Chung Valley development
to avoid cumulative impacts during the construction phase. Also a noise bund
has been proposed to mitigate operational impacts on the future primary school
in Area 40 of Tung Chung Valley. These
measures are sufficient to fully mitigate any cumulative impacts and additional
mitigation measures are not considered as being required.