This Section
summarises the environmental outcomes associated with the construction and
operation of the proposed biodiesel plant at TKOIE.
10.2.1
Construction
Phase
The Project Site has been
formed and is currently vacant. No major
earthworks will be required for the site formation works and only minor
excavation works will be required for the construction of the foundation works
and site utilities. The storage tanks
and process equipment will be pre-fabricated off-site and assembled on site using hydraulic and tower cranes and hence minimal
dust will be generated from this activity.
Dust generated from the minor excavation works and concreting works for
the construction of site buildings will be minimal.
The
jetty will be constructed in form of a piled deck and no dredging of marine sediment will
be required. Marine piles will be
drilled through the existing rubble mound seawall to the competent bearing strata by a piling rig
placed on a temporary steel platform.
Concrete infill to piles will be undertaken prior to placement of
trellis beam and pre-cast concrete panels.
The dust and air emissions generated from the marine works will be
minimal.
With the implementation of dust suppression measures
stipulated under the Air Pollution
Control (Construction Dust) Regulation and the adoption of good site
practices, no adverse construction dust impact is anticipated. Dust monitoring during the construction phase
is therefore considered not necessary.
Monthly site audits will be undertaken to ensure the
implementation of recommended dust control measures and good site practices
during construction phase.
10.2.2
Operational
Phase
The stacks of the boiler and biogas flare (if in
operation), and the exhaust of the
The potential odour impact
due to the discharge of exhaust air from the final air scrubber of the on-site
wastewater treatment plant has been evaluated.
After scrubbing, the odour concentration will
be significantly reduced. The predicted odour concentrations at the identified ASR are well below the odour criterion. The operation of the biodiesel plant will not cause
adverse odour impacts to the identified ASRs.
The
concentrations of
Odour concentration at the stack of the final
air scrubber will be monitored for the first two years of operation of the
biodiesel plant and odour patrols along the Project Site boundary will also be
carried out to confirm that the operation of biodiesel plant will not cause
adverse odour impacts.
With the implementation of proper design, the
recommended mitigation measures and monitoring programme,
it is concluded that the construction and operation of the biodiesel plant will
not cause adverse air quality impacts and will comply with the EIAO-TM requirements.
10.3.1
Construction
Phase
The
predicted construction noise levels at the identified NSRs
range from 48 dB(A) to 64 dB(A) and 48 to 55dB(A) for
residential premises and an educational institution, respectively. These levels are well below the noise
criteria of 75 and 70 dB(A) for domestic premises and
educational institutions, respectively. Therefore, the identified NSRs within the Study Area will not be adversely affected
by the construction of the Project.
Good construction site practices (see Section 5.7) will be implemented by the Contractor to further
minimise the noise impact.
Noise
monitoring during construction phase is considered not necessary. However, monthly site inspections will be
carried out to audit the compliance of the Contractor with regard to noise
control and to recommend further mitigation measures if found to be necessary.
10.3.2
Operational
Phase
The
operational noise impact assessment was undertaken based on a set of
conservative assumptions. To minimise
potential noise impact to NSRs, all noisy equipment in the fat preparation
plant, wastewater treatment plant, steam boiler room and process building will
be located within completely enclosed buildings or complete noise enclosures. Due to the large separation distances between
the identified NSRs and the noise sources at the
biodiesel plant, the predicted noise levels at the NSRs
due to the operation of the biodiesel plant range from 40to 49 dB(A) and 36 to
45 dB(A) during the day-time and night-time periods, respectively. These noise levels comply with the
corresponding day-time and night-time noise criteria of 60 and 50 dB(A).
In
view of the predicted insignificant noise impact during the operational phase,
noise monitoring work is considered to be not necessary.
10.4.1
Construction
Phase
The construction works for the Project will mainly be
land-based. With respect to the nature
and relatively small scale of the land based construction activities, the
potential water quality impacts are considered minimal with the implementation
of the good practices outlined in ProPECC PN 1/94 “Construction Site Drainage”.
The proposed jetty (50m long and 26m wide) will be in
a form of a reinforced concrete deck supported by the marine piles. No dredging or reclamation works will be required. A total of about 60 piles (approximate diameter
of 1 m each) will be constructed. Bore piles will be
driven through the existing rubble mound seawall. The water quality impacts due to the piling
activities will be minimal and no adverse water quality impact is
anticipated.
The cross-sectional area of
each pile underwater has been estimated to be 0.8m2. It is estimated that the volume of each pile
underwater will range from 0.8 m3 to 9.6m3. Although there
may be localised effects due to the physical
resistance of the piles, the water flow through the piled structure will
generally be maintained. It is not
expected that the piles will result in any adverse impact to the water flow
regime at the jetty during the operational phase.
As
no adverse water quality impact is anticipated, no water quality monitoring is
considered necessary during the construction phase.
10.4.2
Operational
Phase
A
surface water drainage system will be provided to collect stormwater
runoff from the Project Site. Clean stormwater runoff will be segregated from potential
contaminated areas. The stormwater from the potential contaminated areas will be
collected and diverted to the on-site wastewater treatment plant for treatment.
Wastewater
from the biodiesel production process will be collected and treated prior to
discharge to the foul sewer leading to the Tseung Kwan O Sewage
Treatment Works.
Bund wall will be provided at the tank farm (including
the storage tank of the raw materials/products) and the process tanks within
the
All
materials to be used and stored on site (except for the gas oil) are
biodegradable and hence the potential for land contamination or environmental
pollution due to the spillage during handling and transfer, and leakage of
tanks will less severe. Nevertheless,
the plant/equipment and tank farm are designed to comply with relevant local
regulations and standards. Measures have been put in place to prevent
spillage of materials during handling and transfer. For example, dry coupling will be
used to connect two loading/unloading pipes or a flexible hose to a transfer
pipe in order to avoid any leakage of the materials at the joint. The loading/unloading area will be bunded to contain any potential spillage of materials. In addition, the operations will be
undertaken at the paved loading/unloading station and will be manned by trained
staff and closely monitored with flow control equipment.
Any spillages will be
contained and the spill be absorbed by appropriate absorbents. The area will be properly washed and the
wastewater will be conveyed to the on-site wastewater treatment plant for
treatment. For accidental spills during
the transportation of biodiesel off the site, retainer booms will be deployed
around the barge and the contaminated areas to prevent the spillage
spreading. An outline emergency
response plan related to pollution prevention and management has been prepared
which will form the basis of the detailed plan. A detailed plan which will detail emergency actions will be prepared
during the detailed design stage.
Based
on the above and with the provision of appropriate mitigation measures, no
adverse water quality impacts are anticipated.
Stormwater and effluent discharged from the
site will be monitored to ensure the discharge will comply with the
requirements of the Water Pollution
Control Ordinance Licence.
10.5.1
Construction
Phase
No
dredging or reclamation works will be required.
Permanent loss of a small stretch ([1])
of low ecological value
marine habitat at the artificial seawall is expected due to the marine works
for jetty construction. Pile surfaces
can, however, serve as artificial habitats for the settlement and recolonisation of marine assemblages. Residual impacts are expected to be low.
As no adverse water quality impact
is expected due to construction activities, there will be no secondary impacts
to ecology. It is considered that environmental monitoring is not
required. Nevertheless, monthly site
inspections will be
undertaken to ensure that the
recommended mitigation measures on water quality are properly implemented such
that secondary adverse impacts on marine ecological resources can be avoided
and minimised.
10.5.2
Operational
Phase
As no adverse water quality and
hydrodynamic impacts are expected due to the operation of the biodiesel plant,
the potential impacts to
marine ecological resources are expected to be minimal. No adverse impacts to marine ecology are
expected.
No
monitoring and audit will be required during the operational phase.
10.6
Risk Assessment
A quantitative
risk assessment (QRA) has been conducted for the operational
phase of the Project. The potential
risks to the off-site population have been estimated based on the population
levels (including the planned population at the vacant land adjacent to the
biodiesel plant). The assessment shows
that the principal hazards to the public are related to catastrophic failures
of the biodiesel and methanol storage tanks.
Potential explosion of methanol vapours in the process area that can
result from a methanol leak also contributes to the overall risk levels. Other
hazardous scenarios considered were found to pose lower risks to the off-site
population.
The overall risk levels estimated for the
operational phase of the Project are relatively low. Individual risk levels at the Project Site boundary are predicted to be well
below the criterion of 1 x 10-5 per year ([2]).
The societal risks expressed in the form of a FN curve lie within the
“acceptable” region of
It is recommended that the mitigation measures
recommended in Section 8.9 should be
audited during the detailed design stage and before the operation of the plant
to ensure that:
·
they have been properly incorporated into the design of the plant;
·
control and management measures are clearly described in the
detailed Emergency Response Plan; and
·
be properly installed and implemented.
The
environmental impact assessment (covering air quality, noise, water quality,
marine ecology and hazard to life) has concluded that no unacceptable
environmental impacts are envisaged due to the construction and operation of
the Project. No long-term unacceptable
impact on the environment is anticipated.
The proposed biodiesel plant will use multi-feedstock
which consists of waste cooking oil (WCO),
oil and grease recovered from grease trap waste (GTW), PFAD (a distillate from palm oil)
and animal fats. It not only
offers a convenient recycling outlet for GTW and WCO but also converts the oil
and grease recovered from these wastes into useful products. The Project also offers a cleaner
alternative to diesel fuel to the