1.
2.
AIR QUALITY
2.1.1
In
accordance with the Contract Specific EM&A Manual, 1-hour and 24-hour Total
Suspended Particulates (TSP) levels should be measured at the designated air quality
monitoring stations to indicate the impacts of construction dust on air
quality. Impact 1-hour TSP monitoring was conducted for at least three times
every 6 days, while impact 24-hour TSP monitoring was carried out for at least
once every 6 days.
2.2
Monitoring Equipment
2.2.1
24-hour
TSP air quality monitoring was performed using High Volume Sampler (HVS)
deployed at the designated monitoring stations. The HVS shall meet all the
requirements of the EM&A Manual.
2.2.2
A
portable direct reading dust meter was used to carry out the 1-hour TSP
monitoring.
2.2.3
The
model of the air quality monitoring equipment used is summarized in Table
2.1.
2.3.1
The
following guidelines were adopted during the installation of HVS:
·
Sufficient
support is provided to secure the samplers against gusty wind.
·
No
two samplers are placed less than 2 meters apart.
·
The
distance between the sampler and an obstacle, such as buildings, is at least
twice the height that the obstacle protrudes above the sampler.
·
A
minimum of 2 meters of separation from walls, parapets and penthouses is
required for rooftop samples.
·
A
minimum of 2 meters separation from any supporting structure, measured
horizontally is required.
·
No
furnaces or incineration flues are nearby.
·
Airflow
around the samplers is unrestricted.
·
The
samplers are more than 20 meters from the drip line.
·
Any
wire fence and gate, to protect the sampler, should not cause any obstruction
during monitoring.
·
Permission
must be obtained to set up the samplers and to obtain access to the monitoring
stations.
·
A
secured supply of electricity is needed to operate the samplers.
2.3.2
Prior
to the commencement of the dust sampling, the flow rate of the high volume
sampler shall be properly set. The power supply should be checked to ensure the
proper functioning of the sampler. The sampler is recommended to be operated
for 5 minutes to establish thermal equilibrium before placing any filter media
at the designated air monitoring station.
2.3.3
The
filter holding frame should be removed by loosening the four nuts and placing
carefully a weighted and conditioned filter at the centre with the stamped
number upwards on a supporting screen.
2.3.4
The
filter should be aligned on the screen so that the gasket formed an airtight
seal on the outer edges of the filter. The filter holding frame should be
tightened to the filter holder with swing bolts. The applied pressure should be
sufficient to avoid air leakage at the edges.
2.3.5
A
programmed timer should be used to control the duration of operation.
Information should be recorded on the record sheet, which included the starting
time, the weather condition and the filter number.
2.3.6
After
sampling process is finished, the filter should be removed and sent to the laboratory
for weighting. The elapsed time should also be recorded.
2.3.7
All
filters should be equilibrated in a conditioning environment for 24 hours
before weighting. The conditioning environment temperature should be between
25°C and 30°C and not vary by more than ±3°C; the relative humidity
(RH) should be <50% and not vary by more than ±5%. A convenient working
RH is 40%.
2.4.1
The
high volume motors and their accessories should be properly maintained,
including routine motor brushes replacement and electrical wiring checking, to
ensure that the equipment and a continuous power supply were in good working
condition.
2.4.2
Initial
calibration of dust monitoring equipment shall be conducted upon installation
and thereafter at fortnightly intervals. The transfer standard shall be
traceable to the internationally recognized primary standard and be calibrated
annually. The calibration certificate for the HVS is provided in Appendix
D.
2.5.1
Portable
Laser Particle Photometer Monitors should be operated in accordance with the
Manufacturer’s instruction Manual as below:
a) Pulling up the air sampling inlet
cover
b) Changing the Mode 0 to BG
c) Pressing Start/Stop switch
d) Turning the knob to SENSI.ADJ and
press it
e) Pressing Start/Stop switch again
f) Returning the knob to the position
MEASURE slowly
g) Pressing the timer set switch to
set measuring time
h) Removing the cap and start the
measurement
2.6.1
ET
shall submit sufficient information to the IEC to prove that the instrument is
capable of achieving comparable results to the HVS. The instrument should also
be calibrated regularly, and the 1-hour sampling shall be determined
periodically by the HVS to check the validity and accuracy of the results
measured by direct reading method. The calibration certificate for the direct
reading dust meter is provided in Appendix D.
2.7.1
In
accordance with the Contract Specific EM&A Manual, four air quality
monitoring locations, namely AMS2, AMS3C, AMS6 and AMS7B were set up at the
proposed locations. AMS2, AMS3C and AMS7B are covered by Contract No.
HY/2019/01 “Hong Kong-Zhuhai- Macao Bridge Hong Kong Boundary Crossing
Facilities – Phase 2 and Other Works”
2.7.2
AMS6
is covered by Contract No. HY/2011/03 “Hong Kong-Zhuhai-Macao Bridge Hong Kong
Link Road (HZMB HKLR) – Section between Scenic Hill and HKBCF”. The ET of the
Contract or another ET of the HZMB project is required to conduct impact air
quality monitoring at AMS6 as part of EM&A programme if this air quality
monitoring station is no longer covered by Contract No. HY/2011/03.
2.7.3
The
most updated locations are summarized in Table
2.2 and the locations of the air monitoring
stations shown in Figure 2.
2.8.1
The
schedule of air quality monitoring in reporting month is provided in Appendix
E.
2.8.2
No
Action / Limit Level exceedance was recorded for 1-hr and 24-hr TSP at AMS2,
AMS3C and AMS7B.
2.8.3
The
monitoring results for AMS6 are reported in the monthly EM&A Reports
prepared for Contract No. HY/2011/03.
2.8.4
The
weather conditions during the monitoring are provided in Appendix
K.
2.8.5
The
monitoring data of 1-hr TSP and 24-hr TSP are summarized in Table 2.3. Detailed
monitoring data are presented in Appendix F.
2.8.6
The
Event and Action Plan for air quality is given in Appendix
H.
2.8.7
The
wind data obtained from the on-site wind station during the reporting period is
provided in Appendix G.