2.1
1-hour TSP and 24-hour TSP monitoring was conducted to monitor the air
quality. Appendix A shows the established Action and Limit Levels for the environmental
monitoring works.
2.2
A High Volume Sampler (HVS – Model GMWS-2310 Accu-Vol) complete with the
appropriate sampling inlets was installed for the 24-hour TSP sampling. The HVS
met all the requirements of the approved EM&A Manual. Portable dust meter
was used to carry out the 1-hour TSP monitoring. Table 2.1 summarises the
equipment that was used in the dust monitoring programme.
Table 2.1 TSP Monitoring Equipment
|
Equipment |
Model |
|
HVS
(for 24-hr TSP measurement) |
GMWS 2310
Accu-Vol system |
|
Calibration
Kit (for HVS) |
GMW 25 |
|
Dust Meter (for 1-hr TSP
measurement) |
Laser
Dust Monitor – Model LD-3 |
Monitoring Parameters, Frequency
and Duration
2.3
The monitoring parameters and frequency are summarised in Table 2.2. The
monitoring schedule for the reporting month is shown in Appendix B.
Table 2.2 Air Quality Monitoring Parameters and
Frequency
|
Location |
Parameter |
Duration |
Frequency |
|
A1, A2 |
1-hour TSP |
1 hour |
3 times every six days |
|
|
24-hour TSP |
24 hours |
Once every six days |
2.4
In accordance with the EM&A Manual, two air quality monitoring
stations, namely A1 and A2, were selected for the 1-hour TSP and 24-hour TSP sampling. The monitoring stations are shown in Figure
2.1.
24-hour TSP Monitoring
Installation
2.5
The HVS was installed in the vicinity of the air sensitive receivers.
The following criteria were considered in the installation of the HVS.
·
A horizontal platform with appropriate support to
secure the sampler against gusty wind was provided.
·
The distance between the HVS and any obstacles,
such as buildings, was at least twice the height that the obstacle protrudes
above the HVS.
·
A minimum of 2 meters separation from walls,
parapets and penthouses was required for rooftop sampler.
·
No furnace or incinerator flues were nearby.
·
Airflow around the sampler was unrestricted.
·
Permission was obtained to set up the samplers and
to obtain access to the monitoring station.
·
A secure supply of electricity was obtained to
operate the sampler.
Preparation of Filter
Papers by ALS Technichem (HK) Pty Ltd.
·
Glass fibre filters, G810 were labeled and sufficient filters that were
clean and without pinholes were selected.
·
All filters were equilibrated in the conditioning environment for 24
hours before weighing. The conditioning
environment temperature was around 25 °C and not variable by more than ±3 °C;
the relative humidity (RH) was < 50% and not variable by more than ±5%. A convenient working RH was 40%.
·
ALS Technichem (HK) Pty Ltd. has comprehensive quality
assurance and quality control programmes.
Field Monitoring
·
The power supply was checked to ensure the HVS works properly.
·
The filter holder and the area surrounding the filter were cleaned.
·
The filter holder was removed by loosening the four bolts and a new
filter, with stamped number upward, on a supporting screen was aligned
carefully.
·
The filter was properly aligned on the screen so that the gasket formed
an airtight seal on the outer edges of the filter.
·
The swing bolts were fastened to hold the filter holder down to the
frame. The pressure applied should be
sufficient to avoid air leakage at the edges.
·
Then the shelter lid was closed and was secured with the aluminum strip.
·
The HVS was warmed-up for about 5 minutes to establish run-temperature
conditions.
·
A new flowrate record sheet was set into the flow recorder.
·
The flow rate of the HVS was checked and adjusted at around 1.2 m3/min. The range specified in the EM&A Manual
was between 0.6-1.7 m3/min.
·
The programmable timer was set for a sampling period of 24 hrs +
1 hr, and the starting time, weather condition and the filter number were
recorded.
·
The initial elapsed time was recorded.
·
At the end of sampling, the sampled filter was removed carefully and
folded in half length so that only surfaces with collected particulate matter
were in contact.
·
It was then placed in a clean plastic envelope and sealed.
·
All monitoring information was recorded on a
standard data sheet.
·
Filters were sent to ALS Technichem (HK) Pty Ltd. for analysis.
Maintenance &
Calibration
·
The HVS and its accessories are maintained in good working condition,
such as replacing motor brushes routinely and checking electrical wiring to
ensure a continuous power supply.
·
HVS is calibrated at bi-monthly intervals using GMW-25 Calibration Kit
throughout all stages of the air quality monitoring.
1-hour TSP Monitoring
Monitoring Procedures
2.6
The measuring procedures of the 1-hour TSP by a dust meter were in
accordance with the Manufacturer’s Instruction Manual as follows:
·
Set POWER to “ON”, push
·
Push the knob at MEASURE position.
·
Push “O-ADJ” button. (Then meter’s indication is 0).
·
Push the knob at SENSI ADJ position and set the meter’s indication to S
value described on the Test Report using the trimmer for SENSI ADJ.
·
Pull out the knob and return it to MEASURE position.
·
Push “START” button.
Maintenance and Calibration
·
The 1-hour TSP Dust Meter would be verified at 1-year intervals
throughout all stages of the construction phase monitoring.
·
The calibration status of the HVS and direct dust meters is summarised
in Appendix G.
2.7
Dust monitoring was conducted as scheduled in the reporting month. All
monitoring data are provided in Appendix C.
2.8
Wind speed and wind direction data were obtained from a
Hong Kong Observatory meteorological station situated in Tuen Mun. The
meteorological data is presented in Appendix D.
2.9
Monitoring of 1-hour TSP was conducted on 15 occasions and 24-hour TSP
was conducted on 6 occasions from 1 to 31 August 2006. The monitoring schedule
for the reporting month is presented in Appendix B.
2.10
All measured 1-hour and 24-hour TSP concentrations were
below the AL Levels. No exceedance was recorded in the reporting month.