3. AIR
QUALITY
3.1
Introduction
3.1.1
The potential for SO2, NO2
and smoke emitted from the diesel-powered equipment during the construction
phase is expected to be minimal as the number of such plant required on-site
will be limited and under normal operation, equipment with proper maintenance
is unlikely to cause significant dark smoke emissions. Notwithstanding, plant
should be regularly maintained to minimise emissions.
3.1.2
The principal source of air pollution during the construction phase
will be dust from exposed site areas, stockpiling, movement of vehicles along
unpaved roads, excavation and handling of construction materials, all of which
will be particularly relevant during the dry seasons.
3.1.3
However, the closest residential sensitive
receivers to the proposed PAFF are low rise residential properties at Lung Kwu
Tan and high rise residential blocks at Melody
Gardens in Tuen Mun, both some 2 and 3km away respectively. In addition, the sensitive receivers are
shielded from the PAFF site by topography.
There is also a planned Holiday Camp to the east along Lung Man Road but
this is about 550m away and as such not within the study area. However, the Shiu Wing Steel facility, cement
plant and proposed Eco
Park at Tuen Mun Area 38
adjacent to the site are considered to be sensitive to construction dust and as
such dust predictions have been undertaken for these.
3.2
Relevant
Legislation
3.2.1
Air quality is regulated through Annex 4 of the Technical Memorandum on
EIA Process (TMEIA) which specifies compliance with the Air Quality Objectives
(AQO) and other standards established under the Air Pollution Control Ordinance
(APCO). The APCO and all regulations
specified by this Ordinance, for example the Air Pollution Control
(Construction Dust) Regulation, should be complied with. The 24 hour Total
Suspended Particulates (TSP) AQO is 260 mg/m3.
3.2.2
In addition to the Air Quality Objectives, the TMEIA stipulates a criteria to
meet the hourly TSP concentration of 500 mg/m3 measured at 298oK (25oC) and 101.325
kPa (1 atmosphere) for construction dust impact assessment.
3.2.3
The Air Pollution Control (Construction Dust) Regulation defines
notifiable and regulatory works for achieving the purpose of dust control for a
number of activities. The Regulation requires any notifiable work shall require
advance notice to EPD. It also requires the contractor to ensure that the
notifiable work and regulatory work will be carried out in accordance to the
Schedule of the Regulation. Dust control and suppression measures are provided
in the Schedule. Notifiable works are site formation; reclamation; demolition,
foundation and superstructure construction for buildings; and road
construction. Regulatory works are building renovation, road opening and
resurfacing, slope stabilisation, and other activities including stockpiling,
dusty material handling, excavation, concrete production, etc. This project is expected to include both
notifiable and regulatory works.
3.2.4
The proposed PAFF is classed as a specified process under Part IV of
the APCO and falls within the category “Organic Chemical Works” described in
Schedule 1 of the Ordinance. The following relevant clause relates to the
tank farm of the proposed PAFF:
“Works, not being a chemical process described in
any other process of the following kinds in which:
(b) any organic liquids, including liquid fuel are stored in
tanks having an installed capacity exceeding 100m3.”
3.3
Mitigation Measures During Construction
3.3.1
Dust predictions are adjacent sensitive receivers show that some
exceedances of both the 1-hour (500 µg/m3) and 24-hour (260 µg/m3) criteria could
arise at Shiu Wing Steel and the EcoPark.
As such twice daily watering of the site and watering of the
construction area every 1.5 hours in the vicinity of SR3c during the works of
site formation, stock piling, dusty material handling and excavation has been
recommended. Also, in accordance with
the Air Pollution Control (Construction Dust) Regulation, the Contractor will
be required to ensure that dust control measures stipulated in the Regulation
should be implemented to control dust emissions. Based upon this, the following dust control
measures are recommended. These measures are also summarised in the
Environmental Mitigation Implementation Schedules in Appendix A.
(i)
watering of the construction area every 1.5 hours in the vicinity of SR1,
SR3a, SR3c and SR3d during site formation, stock piling, dusty material
handling and excavation works;
(ii)
The Contractor shall, to the satisfaction of EPD, install effective
dust suppression measures and take such other measures as may be necessary to
ensure that at the site boundary, dust levels are kept to acceptable levels;
(iii)
The Contractor shall not burn debris or other materials on the works
areas;
(iv)
provide site hoarding not less than 2.4m at site boundary;
(v)
in hot, dry or windy weather, a watering programme shall maintain all
exposed road surfaces and dust sources wet;
(vi)
dust creating activities shall be reprogrammed to avoid periods of high
winds;
(vii)
where breaking of oversize rock/concrete is required, watering shall be
implemented to control dust. Water spray shall be used in dry conditions during
the handling of fill material at the site and at active cuts, excavation and
fill sites where dust is likely to be created;
(viii)
open dropping heights for excavated materials shall be controlled to a
maximum height of 2m to minimise the fugitive dust arising from unloading;
(ix)
during transportation by truck, materials shall not be loaded to a level
higher than the side and tail boards, and shall be dampened or covered before
transport. Materials having the
potential to create dust shall not be loaded to a level higher than the side
and tail boards, and shall be covered by a clean tarpaulin. The tarpaulin shall be properly secured and
shall extend at least 300mm over the edges of the side and tail boards;
(x)
no earth, mud, debris, dust and the like shall be deposited on public
roads. Wheel washing facility shall be usable
prior to any earthworks excavation activity on the site;
(xi)
areas of exposed soil shall be minimised to areas in which works have
been completed shall be restored as soon as is practicable;
(xii)
all stockpiles of aggregate or spoil shall be enclosed or covered and
water applied in dry or windy conditions; and
(xiii)
provide awareness training in the need to minimise dust.
3.3.2
If the above measures are not sufficient to manage dust generation,
upon the advice of the ETL, the Contractor shall liaise
with the ES regarding other mitigation measures and consult the IEC for their
effectiveness, and then propose these measures to the FSR for approval prior to
the implementation of the measures.
3.4
EM&A Requirements
3.4.1
EM&A is recommended during the construction phase only
and the effective management of dust arisings during the construction phase
will be monitored through the site audit programme.
3.4.2
The aims of the dust audit are:
¨
to ensure that appropriate measures, including but not
limited to those measures stipulated above, as being implemented with the aim
to minimise and control dust arisings from the site; and
¨
to encourage good site practices.
3.4.3
The Contractor shall be required to pay attention to the
environmental standard and guidelines detailed in Section 3.2 and carry out
appropriate dust management measures.
3.4.4
During the site inspections and the document review
procedures as mentioned in Chapter 11 of this Manual, the ES shall pay special
attention to the issues relating to dust management and check whether the
Contractor has followed the relevant contract specifications and the procedures
specified under the laws of Hong Kong (see
above Section 3.2).
3.4.5
The Contractor’s dust management practices should be
audited with reference to the checklist detailed in Table 3.1 below:
Table 3.1 Dust
Management Checklist
|
Activities
|
Timing
|
Monitoring
Frequency
|
If non-compliance,
Action Required
|
|
Twice daily watering programme of exposed areas.
|
Throughout the works
|
Twice daily
|
The ETL shall inform the Contractor, FSR and IEC of the
non-compliance. The FSR shall instruct
the Contractor to initiate watering more frequently. Corrective action shall
be undertaken within 48 hours. The ETL shall ensure that corrective action
has been taken.
|
|
No burning of material on-site.
|
Throughout the works
|
Weekly
|
The ETL shall inform the Contractor, FSR and IEC of the
non-compliance. The FSR shall instruct
the Contractor to cease burning material.
The Contractor shall immediately suspend burning on site.
|
|
Watering programme of exposed areas in hot, dry or windy
weather.
|
Throughout the works
|
Weekly
|
The ETL shall inform the Contractor, FSR and IEC of the
non-compliance. The FSR shall instruct
the Contractor to initiate watering not less than once daily. Corrective
action shall be undertaken within 48 hours. The ETL shall ensure that
corrective action has been taken.
|
|
Dusty activities shall not be programme in periods of
high winds
|
Throughout
the works
|
Weekly
|
The ETL shall inform the Contractor, FSR and IEC of the non-compliance. The FSR shall instruct the Contractor to
reschedule the works accordingly.
|
|
Water spraying during rock or concrete breaking.
|
Throughout the works
|
Weekly
|
The ETL shall inform the Contractor, FSR and IEC of the
non-compliance. The FSR shall instruct
the Contractor to implement spraying. Corrective action shall be undertaken
within 48 hours. The ETL shall ensure that corrective action has been taken.
|
|
Dropping
heights shall be minimised to 2m.
|
Throughout
the works
|
Weekly
|
The ETL shall inform the Contractor, FSR and IEC of the
non-compliance. The FSR shall instruct
the Contractor to reduce dropping height. The ETL shall ensure that
corrective action has been taken.
|
|
Demolition material/waste in dump trucks are properly
covered before leaving the site.
|
Throughout the works
|
Weekly
|
The ETL shall inform the Contractor, FSR and IEC of the
non-compliance. The FSR shall instruct
the Contractor to comply. The Contractor
shall prevent trucks shall leaving the site until the waste are properly
covered. The ETL shall ensure that corrective action has been taken.
|
|
Stockpiles contained so as not to cause a dust nuisance.
|
Throughout the works
|
Weekly
|
The ETL shall inform the Contractor, FSR and IEC of the
non-compliance. The FSR shall instruct
the Contractor to cover the spoil or implement watering. The ETL shall ensure
that corrective action has been taken.
|
|
Wheel washing facilities are used and effective
|
Throughout the works
|
Weekly
|
The ETL shall inform the Contractor, FSR and IEC of the
non-compliance. The FSR shall instruct
the Contractor to use wheel washing facilities. The ETL shall ensure that
corrective action has been taken.
|
Note: ETL –
Environmental Specialist, IEC – Independent Checker (Environmental), FSR –
Franchisee Site Representative
3.4.6
Should any ad hoc spot check monitoring be required of the
Total Suspended Particulates (TSP) levels, this shall comprise monitoring of
1-hour TSP levels measured by direct reading methods. Any ad hoc monitoring shall be carried out by
the Environmental Team Leader (ETL) (see Section 1) to ensure that construction
works are not generating dust which exceeds the acceptable level.
3.4.7
Other relevant data including weather conditions and any
other special phenomena and work progress of the concerned site shall be
recorded in detail by the ETL. A sample data
sheet is shown in Figure 3.1.
3.4.8
The Contractor is responsible for provision of the
monitoring equipment if required and shall ensure that direct reading samplers
with an appropriate calibration kit are available for carrying out ad hoc
measurements if required. Calibration of dust monitoring equipment shall be
conducted by the ETL in accordance with the manufacturer’s recommendations. The
calibration data shall be properly documented for future reference by concerned
parties, such as the IEC.
3.4.9
Wind data monitoring equipment shall also be provided for
logging wind speed and wind direction near to the dust monitoring locations if
monitoring is required. The equipment installation location shall be proposed
by the Contractor in consultation with the ETL and agreed with the FSR, in
consultation with the IEC. For
installation and operation of wind data monitoring equipment, the following
points shall be observed:
(i) the wind sensors should be installed on
masts at an elevated level 10 m above ground so that they are clear of
obstructions or turbulence caused by the buildings;
(ii) the wind data should be captured by a data
logger to be down-loaded for processing at least once a month;
(iii) the wind data monitoring equipment should
be re-calibrated at least once every six months; and
(iv) wind direction should be divided into 16
sectors of 22.5 degrees each.
3.4.10
In exceptional situations, the ETL may propose alternative
methods to obtain representative wind data upon approval from the FSR and
agreement from the IEC.
3.4.11
When selecting sites for ad hoc monitoring, the following
preferred locations and factors shall be considered:
(i)
the site boundary or locations close to the major dust
emission source; and
(ii)
the prevailing meteorological conditions.
3.4.12
The ETL shall agree with the FSR, in consultation with the
IEC, the position of the ad hoc monitoring.
Figure 3.1 Data Sheet for TSP
Monitoring
Field
Operator :