This EIA has focused on identifying and providing mitigation options for the potential impacts associated with the construction and operation of the 132kV circuit from Pui O Substation to Cheung Chau Substations.
The following aspects have been assessed:
· Construction Impacts including Air Quality, Noise and Water Quality;
· Waste Management Implications;
· Human Health;
· Cultural Heritage; and
· Landscape and Visual Impacts.
The residual impacts define the acceptability of the project, and are categorised in general accordance with guidance offered by the Technical Memorandum on Environmental Impact Assessment Process (EPD, 1997). Five impact categories have been adopted:
· The impact is beneficial if the project will improve the overall quality of the environmental aspect under consideration;
· The impact is acceptable if the assessment indicates that there will be no significant effects on the environmental aspect under consideration;
· The impact is acceptable with mitigation measures if there will be some adverse effects, but these can be eliminated, reduced or offset to a large extent by specific measures;
· The impact is unacceptable if the adverse effects are considered excessive and are unable to be practically mitigated. In these circumstances compensation may have to be considered by Government; and
· The impact is undetermined if significant adverse effects are likely, but the extent to which they may occur or be mitigated cannot be determined from the study. Further detailed study will be required.
The time scale over which the impacts will occur has also been categorised into short, medium or long term, and reversible or irreversible. No residual impacts are expected.
assessment on the construction dust impacts has identified that fugitive dust
is the primary potential air pollutant during the proposed works and the dust
impact will be minimal. Established
dust suppression techniques such as regular watering, covering/dampening any
stockpiles and dampening dusty materials before transportation, have been
proposed. Through the proper
implementation of the recommended mitigation measures, dust generation will be
further controlled and exceedance of the acceptable criteria will not be
expected. As a result, no routine air
quality monitoring will be required.
This EIA has concluded that the predicted
construction noise levels without mitigation at all the affected NSRs except
for SR3 will exceed the acceptable noise criteria. With the implementation of
good site practice and practical noise mitigation measures, the construction
noise impacts will be reduced. After the implementation of
noise mitigation measures, residual construction noise impact will only occur
at SR5, the Buddhist Wai Yan Memorial College. However, it is anticipated that
the exposure to high noise level is only a short duration (2 to 3 days). In
addition, the road breaking activity in front of the school is recommended to
be carried out during the non-teaching period of the school (i.e. Saturday
afternoon and school holidays). The residual impact can be mitigated.
As noise exceedances during the construction phase are not predicted and the laying underground land cable is a trade practice well established by CLP, routine environmental noise monitoring is not required during construction. However regular site audits are recommended to be conducted to ensure the implementation of good site practice and appropriate mitigation measures.
(throughout the year)
The construction programme has scheduled the cable laying work during the dry season. The results of the assessment confirm that cable laying work can be carried out without any adverse water quality impact during the dry season. Even cable laying work is required during the wet season, the water quality can also comply with the WQO with the implementation of the above-mentioned mitigation measures.
It can conclude that for direct burying method,
exceedances of SS levels take place only at Po Yue Wan during wet season neap
tide. Since Po Yue Wan is not a water
sensitive receiver, the predicted SS levels at all the water sensitive
receivers comply with the relevant WQO. Therefore, the water quality impact is
acceptable. No exceedances of SS levels at all the monitoring
locations are predicted with dredging one trench but exceedances occur at
Cheung Chau typhoon shelter, Po Yue Wan and Adamasta Channel when three
trenches are dredged simultaneously. With the implementation of the general
mitigation measures and pollution prevention measures, the water quality
impacts at the water sensitive receivers are not expected. An environmental monitoring and audit will be
implemented to ensure the general mitigation measures are effective and that
the actual water quality impacts are within the acceptable levels during the
installation of submarine cables and the reclamation works at Pui O Beach.
A review of existing
information indicates that the Study Area supports fisheries resources.
As impacts resulting from the project will be
confined to dredging and reclamation, no adverse impacts to fisheries resources
are expected.The potential impact on
the spawning and nursery ground is anticipated to be insignificant.
The size of impact due to dredging and reclamation is predicted to minor.
mitigation measures which are recommended to control water quality impacts to
within acceptable levels, are also expected to control impacts to fisheries
Therefore, no fisheries-specific
mitigation measures are required.
Literature reviews of
existing information supplemented with the results of recently undertaken field
surveys on marine ecological resources indicate that the intertidal rocky
shores within the Study Area are of medium ecological value whereas for the
sandy habitats, low ecological value was assigned. Soft bottom subtidal habitats identified in the review were
regarded as of low ecological value. A
few isolated colonies of hard and soft corals were recorded on the subtidal
hard surface habitats and were considered as of low ecological value. The waters near the proposed
reclamation and submarine cable laying sites do not appear to be highly
utilised by marine mammals and it is considered that this area does not contain
critical habitat for the Indo-pacific Hump-backed dolphins and Finless
Potential impacts to marine
ecological resources from the proposed construction works may arise either
indirectly, e.g. through perturbations of the surrounding water quality, or
directly as a result of habitat loss. A
total of 0.055 ha intertidal sandy
shore habitat, small areas of rocky shore and 0.5
ha of subtidal soft bottom assemblages will be permanently lost as a result of the construction activities associated
with the Project. However, the
assemblages to be lost are of low-medium ecological value and given the small
area to be directly affected, the impacts are unlikely to be severe. Indirect impacts during the construction
process, such as an increase in SS levels and decrease in DO in the water
column may impact intertidal and subtidal filter feeders and other marine
organisms. However, the effects are not
expected to be severe and no unacceptable impacts are predicted to occur.
Operational impacts to marine ecological resources are not predicted to occur through disturbances to water quality due to changes in the hydrodynamic regime of the area or an increase in marine traffic for cable maintenance and repair.
Literature reviews of existing information supplemented with the results of field surveys on cultural heritage resources indicate that 31 historical buildings and features and two known archaeological sites are located within the Study Area. The proposed development has tried to avoid the heritage sites as far as possible but concerns have been raised regarding the potential impact on some of the identified sites.
Mitigation measures have
been recommended to avoid impacts to cultural heritage resources; control of
the construction work schedule during peak visiting hour at Pui O Tin Hau
Temple; detail design of the underground cable construction to avoid and
minimise the potential impact to the archaeological deposit at Bui O Public
School (Site A) and inner raised beach at Pui O (Site B). The future road level of the proposed Chi Ma
Wan Road widening shall be raised to allow adequate cover requirement for the
cables which shall be laid above the concerned zone. If the avoidance of
reaching the `no dig’ zone below existing ground level at
both Site A and Site B is not
possible, archaeological monitoring should be
undertaken in this section during construction to preserve the archaeological
deposit, if any, by record and take environmental samples for future study if
The Landscape and Visual
Impact Assessment highlights that the significant adverse impacts will occur
during the construction phase. Significant impacts are also restricted to
particular locations, namely Pui O tunnel and Tai Long Wan tunnel portals and
Cheng Chau landfall
mitigation measures the long term adverse impacts will be
negligible. The alignment of the circuit is significantly constrained by the
technical engineering requirements.
However, the nature of the proposed works and construction methodology
means that much of the cable can be constructed with minimal disturbance to the
existing landscape owing to the limited working boundary along existing roads,
footpaths. Therefore, the proposed works
will have limited adverse impacts or negligible impacts on baseline condition
with appropriate mitigation measures. In conclusion, the landscape and visual
impacts are considered acceptable with mitigation measures.
In order to suitably manage the potential environmental effects associated with construction related wastes, full consideration must be given of the re-use of surplus clean material on site (where practicable), or within other development projects, once material balances are finalised. All mitigation measures and waste management procedures outlined within the EIA must be implemented in order to control or eliminate the potential impacts to the environment from waste generation and disposal.
13.10 Health Effect
The predicted EMFs for the proposed underground cables, cables in tunnel and submarine cables will be well under the stipulated guideline limits (below 1/5 of guideline limits) issued by the ICNIRP. As such, the existence of EMF associated with the proposed project is not anticipated to pose any adverse impact on public health.
Based on the findings of the baseline review, geophysical survey and diver inspection, it was confirmed that no archaeological significant material was identified in the study area. Therefore any further archaeological investigation or mitigation measures are not required.
An environmental monitoring and audit (EM&A) programme is recommended to be undertaken during the implementation of the Project. This is summarised herein and will be elaborated upon in the EM&A Manual.