2.1
According
to the EM&A Documents for HKLR listed in Table 1.1, baseline air quality monitoring
shall be carried out for a period of fourteen days, in terms of 1-hour and
24-hour Total Suspended Particulates (TSP) at all the monitoring locations. Monitoring
of 1-hour TSP shall be carried out at least three times per day while that of 24-hour
TSP shall be conducted daily for 14 consecutive days.
2.2
Baseline
air quality monitoring was conducted at the two monitoring stations under the Contract, as shown in Figure 2. Table
2.1 describes the locations of the air quality monitoring stations.
Table 2.1 Location
for Air Quality Monitoring Locations
|
Monitoring Stations |
Location |
|
AMS 1 |
Sha Lo Wan |
|
AMS 4 |
San Tau |
2.4
Wind data monitoring equipment was set at Rooftop of
Village Office at San Tau for logging wind speed and wind direction such
that the wind sensors are clear of obstructions or turbulence caused by building.
The wind data monitoring equipment is re-calibrated at least once every six
months and the wind directions are divided into 16 sectors of 22.5 degrees
each. The location is shown in Figure 2.
2.5
The
equipment used in the baseline air quality monitoring programme and
copies of the calibration certificates for the equipment
can be referred to the Baseline Environmental
Monitoring Report for HKBCF.
2.6
Table 2.2
summarizes the monitoring parameters, monitoring period and frequencies of
baseline air quality monitoring.
Table 2.2 Frequency
and Parameters of Air Quality Monitoring
|
Monitoring
Station |
Location
for Measurement |
Parameter |
Period |
Frequency |
|
AMS 1 |
Area in front of No. 9 Sha Lo Wan |
1-hour TSP 24-hour TSP |
0700-1900 24 hours |
3 times/day Daily |
|
AMS 4 |
San Tau (Rooftop of Village Office) |
2.7
Weather data was recorded during the baseline
period can be referred to the Baseline Environmental Monitoring Report for
HKBCF. The air temperature, precipitation
and the relative humidity data was obtained from Hong Kong Observatory where
the wind speed and wind direction were recorded by the installed Wind Anemometer.
The general weather conditions (i.e. sunny, cloudy or rainy) were recorded by
the field staff’s observation on the monitoring days.
2.8
High volume Samplers (HVS) completed with
appropriate sampling inlets were employed for air
quality monitoring. Each sampler was
composed of a motor, a filter holder, a flow controller and a sampling inlet
and its performance specification complies with that required by USEPA Standard
Title 40, Code of Federation Regulations Chapter 1 (Part 50).
2.9
The following guidelines were adopted during the
installation of HVS:
·
Sufficient
support was provided to secure the samplers
against gusty wind.
·
No two samplers were placed less than 2 meters
apart.
·
The distance between the sampler and an
obstacle, such as buildings, was at least twice the height that the obstacle
protrudes above the sampler.
·
A minimum of 2 meters of separation from walls,
parapets and penthouses was required for rooftop samples.
·
A minimum of 2 meters separation from any
supporting structure, measured horizontally was required.
·
No furnaces or incineration flues were nearby.
·
Airflow around the sampler was unrestricted.
·
The samplers were more than 20 meters from the
drip line.
·
Any wire fence and gate, to protect the sampler,
should not cause any obstruction during monitoring.
2.10
Fiberglass filters were used [Note: these
filters have a collection efficiency of larger than 99% for particles of 0.3μm diameter].
A HOKLAS accredited laboratory, Wellab Ltd.,
was responsible for the preparation of 24-hr conditioned and pre-weighed filter
papers for Cinotech’s monitoring team.
2.11
All filters, which were prepared by Wellab Ltd., were equilibrated in the conditioning
environment for 24 hours before weighing.
The conditioning environment temperature was around
2.12
Wellab Ltd. has a comprehensive
quality assurance and quality control programmes.
2.13
Operating/analytical procedures for the air
quality monitoring were highlighted as follows:
·
Prior to the commencement of the dust sampling,
the flow rate of the HVS was properly set (between
·
The power supply was checked to ensure the
sampler worked properly.
·
On sampling, the sampler was operated for 5
minutes to establish thermal equilibrium before placing any filter media at the
designated air quality monitoring station.
·
The filter holding frame was then removed by
loosening the four nuts and carefully a weighted and conditioned filter was
centered with the stamped number upwards, on a supporting screen.
·
The filter was aligned on the screen so that the
gasket formed an airtight seal on the outer edges of the filter. Then the filter holding frame was
tightened to the filter holder with swing bolts. The applied pressure should be
sufficient to avoid air leakage at the edges.
·
The shelter lid was closed and secured with the
aluminum strip.
·
The timer was then programmed. Information was recorded on the record
sheet, which included the starting time, the weather condition and the filter
number (the initial weight of the filter paper can be found out by using the
filter number).
·
After sampling, the filter was removed and sent
to the Wellab Ltd. for weighing. The elapsed time was also recorded.
·
Before weighing, all filters were equilibrated
in a conditioning environment for 24 hours. The conditioning environment
temperature should be between
2.14
The following maintenance/calibration was
required for the HVS:
·
The high volume motors and their accessories
were properly maintained. Appropriate maintenance such as routine motor brushes
replacement and electrical wiring checking were made to ensure that the
equipment and necessary power supply are in good working condition.
·
All HVS were calibrated (five point calibration)
using Calibration Kit prior to the commencement of the baseline monitoring and
thereafter at bi-monthly intervals.
2.15
The measuring procedures of the 1-hour dust
meter are in accordance with the Manufacturer’s Instruction Manual as follows:
·
The 1-hour dust meter is placed at least 1.3
meters above ground.
·
Set POWER to “ON” and make sure that the battery
level was not flash or in low level.
·
Allow the instrument to stand for about 3
minutes and then the cap of the air sampling inlet has been released.
·
Push the knob at MEASURE position.
·
Set time/mode setting to [BG] by pushing the
time setting switch. Then, start
the background measurement by pushing the start/stop switch once. It will take 6 sec. to complete the
background measurement.
·
Push the time setting switch to change the time
setting display to [MANUAL] at the bottom left of the liquid crystal display. Finally, push the start/stop switch to
stop the measuring after 1 hour sampling.
·
Information such as sampling date, time, count value and site condition were recorded during the
monitoring period.
2.16
The following maintenance/calibration is
required for the 1-hour dust meter;
·
Check and calibrate the meter by HVS to check
the validity and accuracy of the results measured by direct reading method at 2-month
intervals throughout all stages of the air quality monitoring.
2.17
Baseline air quality monitoring was conducted at
two monitoring stations, namely
AMS1 - Sha Lo Wan and AMS4 - San Tau in the period between 18th October
2011 and 31st October 2011. The detailed monitoring schedule
is shown in Appendix A.
2.18
The monitoring data are summarized in Tables 2.3
and 2.4. All monitoring data and graphical presentations of
1-hour and 24-hour TSP can be referred
to Appendix G and the Baseline Environmental Monitoring
Report for HKBCF respectively. Detailed
weather conditions during the baseline monitoring period are shown in Appendix B.
Table
2.3 Summary of Baseline 1-hour
TSP Monitoring Results
|
Monitoring Station |
Average TSP Concentration, μg/m3 (Range) |
|
AMS1 - Sha
Lo Wan |
202.2 (67.6 – 353.5) |
|
AMS4 - San Tau |
157.1 (55.7 – 264.6) |
Table
2.4 Summary of Baseline 24-hour
TSP Monitoring Results
|
Average TSP Concentration, μg/m3 (Range) |
|
|
AMS1 - Sha Lo Wan |
62.2 (39.0
– 87.8) |
|
AMS4
- San Tau |
62.4 (33.5
– 124.0) |
2.19
The weather was generally sunny and
fine during the baseline monitoring period.
2.20
During the baseline air
quality monitoring period, the influencing
factors which may affect the results are
summarized in Table 2.5:
Table
2.5 Influencing Factors at
Dust Monitoring Stations
|
Monitoring Station |
Influencing Factors |
|
AMS
1 |
Shallow
sand beach nearby |
|
AMS
4 |
N/A |
2.21
The Action and Limit Levels have been set in
accordance with the EM&A Documents
for HKLR, which are summarized in Table
2.6.
Table
2.6 Guidelines for
Establishing Action and Limit Levels for Air Quality
|
Parameters |
Action Level |
Limit Level |
|
1-hour TSP Level in μg/m3 |
For
baseline level ≤ 384μg/m3, Action
level = (Baseline level * 1.3 + Limit level)/2 For
baseline level > 384μg/m3, Action
level = Limit level |
500 |
|
24-hour TSP Level in μg/m3 |
For baseline level ≤
200μg/m3, Action level = (Baseline level * 1.3 + Limit
level)/2 For
baseline level > 200μg/m3, Action
level = Limit level |
260 |
2.22
Following the above guidelines, the Action and
Limit Levels for air quality impact monitoring have been set, as presented in Tables 2.7
and 2.8.
Table
2.7 Action and Limit Levels
for 1-hour TSP
|
Location |
Action
Level, μg/m3 |
Limit Level, μg/m3 |
|
AMS1 |
381 |
500 |
|
AMS4 |
352 |
Table
2.8 Action and Limit Levels
for 24-hour TSP
|
Location |
Action Level, μg/m3 |
Limit
Level, μg/m3 |
|
AMS1 |
170 |
260 |
|
AMS4 |
171 |