Summary of The EIA
The main source of air quality impacts
would be from the construction works.
With the implementation of the recommended mitigation measures i.e. extensive
watering of the haul roads, the air modelling results showed that the total
suspended particulates level at all air sensitive receivers (ASRs) would be
within the dust criteria. Odour nuisance from the excavated materials are
considered to be minimal and mitigation measures are recommended to limit its
A cumulative dust impact assessment
from this Project and the “Improvement work of Ho Chung Road” was carried out.
Assessment results indicated that the cumulative dust levels at all ASRs would
comply with relevant dust criteria.
Construction of the proposed drainage
improvement works is likely, if unmitigated, to generate high noise levels
exceeding 75 dB(A) Leq(30-min) at the Noise Sensitive Receivers (NSRs) identified in close proximity to the
proposed work sites. The predicted noise levels at the
representative NSRs range from
65 dB(A) to 97 dB(A). Adverse noise impacts due to the use of powered
mechanical equipment would occur at these sensitive receivers if noise control
measures were not implemented.
The most effective mitigation measure
is to control the noise emissions from the powered mechanical equipment used on
site. This would involve either selecting silenced equipment, or reducing the
transmission of noise using mufflers, silencers, or acoustic enclosures.
Receiver-specific measures that include the use of movable noise barriers and
temporary noise barrier will further alleviate the potential construction noise
impacts. In this Study, with adoption of silenced equipment, movable noise
barriers and temporary noise barrier, the mitigated noise levels at all NSRs
due to this Project would comply with the daytime construction noise standard
as set out in the EIAO-TM.
An indicative assessment was undertaken
for cumulative noise impact arising from this Project and the “Improvement work
of Ho Chung Road”. Assessment results indicated that the cumulative noise
levels at NSRs would comply with noise criteria of 75dB(A) stipulated in the
The key issue in terms of water
quality would be related to excavation works for the drainage improvement works
during the construction stage. Working method controls have been recommended to
minimise potential water quality impacts during excavation of the earth
channel. In particular, excavation works for the earth channel at each river
would be carried out in dry condition by diverting the stream flow from
upstream of the site and containment measures would be used within the channel
to prevent water from entering the excavation area. Other mitigation measures
include control measures on runoff and drainage from the works areas to
minimise construction runoff, proper site management and good housekeeping
practices to ensure construction wastes not entering the adjacent watercourses.
With the implementation of these recommended mitigation measures, unacceptable
impacts on water quality would not be anticipated.
The main waste arising would be
excavated material from the drainage improvements works for the three river
channels, and would comprise soil, sand, gravel and small rocks. Other wastes generated by the construction
activities are likely to include general refuse from the workforce, chemical
wastes from plant and vehicle maintenance, and construction & demolition
(C&D) material from the demolition of existing structures and site
Excavated material with suitable
characteristics should be reused on-site as far as practicable. Surplus public fill generated from the
Project is proposed to be disposed of to the fill bank at Tseung Kwan O Area
137, and C&D waste is proposed to be disposed of to the South East New
Territories Landfill Site. Provided that these identified waste arisings are to
be handled, transported and disposed of using the recommended methods and good
site practices are to be strictly followed, adverse environmental impacts would
not be expected.
An account of the present and
historical land uses along the proposed drainage improvement areas of the three
river channels indicated that activities related to land contamination impact
was not identified in or near to Sai Kung River and Ho Chung Channel. However,
two workshops associated with contaminating uses were noted to be present near
Pak Kong River, and the main type of activities was related to vehicle
A preliminary Contamination Assessment
Plan (CAP) has been prepared which proposed further investigation on the
workshop areas falling within the project boundary of Pak Kong River. Due to
the possible changes of land use and site conditions, a review of the CAP would
be required by the future Environmental Team at a later stage after land
It is considered that the potential
residual impacts would not be significant provided that any identified
contaminated land would be remediated to the acceptable standards prior to the
site clearance/excavation works, and the mitigation measures recommended would
be properly implemented during the construction stage of the Project.
Nine-month ecological surveys covering
the wet and dry seasons were undertaken to establish the ecological profile of
the Sai Kung & Sha Ha, Pak Kong and Ho Chung Assessment Areas. The
Assessment Areas included several areas (Conservation Areas, Coastal Protection
Areas, Country Park/Special Area) of recognised conservation interest.
Seven major habitat types were
identified within the Assessment Areas, comprising Rivers/Streams, Cultivation
Land, Woodland and Fung Shui Woodland,
Shrubland, Developed and Village Areas, Mangrove, and Marine Habitat. Several
plant species of conservation interest were found in the Assessment Areas,
including one rare tree species (Ehretia
acuminata) recorded inside the proposed Ho Chung Works Area.
A total of 64 bird species were
recorded in the Assessment Areas during recent surveys, 12 of which are
considered of conservation interest. One fish, one snake, one butterfly and
three mammal species of conservation interest were also recorded from the
Assessment Areas during recent surveys.
The primary direct ecological impact
resulting from the Project would be the loss of small sections of moderate
ecological value lowland rivers. The proposed works are also anticipated to
directly affect several individuals of the rare tree Ehretia acuminata.
Other direct impacts would include the
loss of 0.83ha low-moderate value cultivation land and 0.91ha low ecological
value village and developed area habitats. Because of the low ecological value
of the affected habitats, these impacts are considered relatively minor.
Indirect impacts would be expected to
include increased sedimentation in aquatic habitats during the construction
phase, and disturbance to wildlife caused by increased human activity and noisy
construction phase activities. Sedimentation is predicted to have only
temporary and localised impacts to aquatic habitats, and is considered a minor
ecological impact. Construction phase disturbance would be temporary, and would
largely affect only low and low-moderate ecological value habitats. As such, it
is considered a minor ecological impact.
Operation phase impacts are expected
to be relatively minor.
Measures to avoid, minimise and
compensate for identified ecological impacts have been recommended. These
include measures to reduce minor construction phase impacts to aquatic
communities resulting from increased sedimentation and disturbance.
Additionally, individuals of the rare tree species Ehretia acuminata affected by the proposed works are recommended to
The design of drainage channels
proposed to replace Sai Kung and Ho Chung Rivers includes the use of natural
substrates for lining newly formed channel beds, recreation of natural
riffle/pool sequences, use of rocked filled gabion to line newly constructed
river banks, and extensive compensatory planting along the channel banks. With
these measures in place, it is expected that aquatic communities found in the
rivers would re-colonise the newly constructed drainage channels. No major
long-term residual impacts to the rivers are anticipated.
With the implementation of the
recommended mitigation measures, ecological impacts resulting from the proposed
drainage improvement works are expected to be relatively minor and environmentally
The unmitigated visual impact of the
Project on the visual sensitive receivers (VSRs) are predicted to be
slight-moderate adverse except at Hiram's Highway near Tai Chung Hau Road where
moderate-significant adverse impact are expected owing to the intrusion of the
new works into existing views. Through the incorporation of mitigation measures
such as planting within the channel, textured concrete walling and compensatory
tree planting, the predicted visual impacts can be reduced to slight adverse
except for VSR3 where moderate adverse residual visual impact would be
Overall, the landscape and visual
impacts of the Project are considered to be acceptable with mitigation
measures. A low level of loss of landscape and visual resources is predicted
and is not considered excessive so as to constitute unacceptable impacts.
However, a key landscape design issue during detailed design will be the need
for a high level of co-ordination and liaison between Government and the design
consultant to ensure that all recommended mitigation measures are effectively
incorporated into the Project. The proposed works would not be acceptable if
these mitigation measures are not incorporated.
The Cultural Heritage Impact
Assessment consists of two sections, an Archaeological Impact Assessment and a
Built Heritage Impact Assessment.
For the Archaeological Impact
Assessment, the desk-based review identified no archaeological potential in the
Ho Chung and Pak Kong works areas. For the work areas at Sai Kung River, the
desk-based review identified there was a potential for archaeological deposits
at the works areas at Sha Ha. However, the field survey results indicate that
no in-situ archaeological deposits remain within the Sha Ha works area
and no mitigation is recommended.
For the Built Heritage Impact
Assessment, the proposed drainage works will have minor effects on the majority
of built heritage features recorded in the survey. The mitigation measures
required for the construction phase of the Project include:
higher earth god shrine should be provided with protective covering if works
come within 1m of the structure. Safe public access should be maintained
throughout the construction period;
For the Che Kung Temple and second earth god
shrine, a vehicle parking area should be maintained or alternative parking
facilities should be made available. Clear signage for directions to the Temple
should be provided from Hiram’s Highway;
of mature trees along all three rivers should be avoided. If it is unavoidable,
any trees that are removed from the area should be replaced by trees of the
channel design should also include proposals for designs that would minimise
any change in character to the environmental setting, such as the incorporation
of building materials for the construction activities, that are compatible to
the existing environment, such as cobbles and gravel and the incorporation of
features that will encourage vegetation
growth along the banks, such as grass concrete and natural verges.
An Environmental Monitoring and Audit
(EM&A) programme will be setup and implemented by the project proponent to
ensure compliance with the recommendations in the EIA Report, to assess the
effectiveness of the recommended mitigation measures, and to identify any
further need for additional mitigation measures or remedial action. Details of
the recommended mitigation measures, monitoring procedures and locations are
presented in a stand-alone EM&A Manual.
This will enable the Contractor to have early warning and provide necessary
action to reduce impacts at specific areas if the assessment criteria are
approached. The effectiveness of
on-site control measures could also be evaluated through a monitoring exercise.
All the recommended mitigation measures should be incorporated into the
EM&A programme for implementation.