2.1
1-hour
and 24-hour TSP levels at two designated monitoring stations were monitored in
the month in accordance with the EM&A Manual. Appendix C shows the established Action and Limit Levels for the
environmental monitoring works.
2.2
The
monitoring schedule for the month is shown in Appendix D. Air quality monitoring stations for 24-hour and 1-hour TSP
measurements are shown in Figure 2.1.
2.3
Portable
dust meter was used to carry out 1-hour TSP monitoring. High volume sampler
(HVS - Model GMWS-2310 Accu-Vol) completed with the
appropriate sampling inlets was installed for 24-hour TSP sampling. The HVS
meet all the requirements as specified in the updated EM&A Manual. Table
2.1 summarised the equipment that were used in the dust-monitoring programme.
Table 2.1 Air Quality Monitoring Equipment
|
Equipment |
Model |
|
Dust Meter
(for 1-hour TSP measurement |
Laser Dust
Monitor – Model LD-3 |
|
HVS (for
24-hour TSP measurement) |
GMWS 2310 Accy-Vol system |
|
Calibration
Kit (for HVS) |
GMW 25 |
Monitoring Parameters, Frequency and Duration
2.3
Table 2.2 summarised the monitoring parameters, frequency
and duration of impact air quality monitoring.
Table 2.2 Air Quality Monitoring Parameters, Frequency and Duration
|
Parameter |
Duration |
Frequency |
|
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, as shown in Figure 2.1 were selected for 24-hour and
1-hour TSP sampling. Table 2.3 describes the location of the air quality
monitoring stations.
Table 2.3 Locations of Air Quality Monitoring Stations
|
Monitoring Station |
Identity / Description |
|
AM1 |
Correctional Services Department Married
Staff Quarters |
|
AM2 |
|
1-hour TSP Monitoring
Monitoring
Procedure
2.5
The measuring procedures of 1-hour TSP by a portable dust
meter are 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 meters are verified at 1-year intervals throughout all stages
of the impact air quality monitoring.
·
Calibration
details for the dust meters are provided in Appendix E.
24-hour TSP Monitoring
Installation
2.6
The HVSs were installed in the
vicinity of the air sensitive receivers. The following criteria were considered
in the installation of the HVSs:
·
A horizontal platform with appropriate support to secure
the samplers 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 provided for rooftop sampler.
·
No furnace or incinerator flues were nearby.
·
Airflow around the sampler was unrestricted.
·
Permission was obtained to set up the sampler and to
obtain access to the monitoring stations.
·
A secure supply of electricity was obtained to operate
the sampler.
Preparation
of Filter papers
·
Glass
fibre filters, G810 were labelled 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. is
a HOKLAS accredited laboratory which has comprehensive quality assurance and
quality control programmes.
Monitoring
Procedures
·
The
power supply was checked to ensure the HVSs work
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 secured with the aluminum
strip.
·
The HVSs were 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 1.1 m3/min. The range 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 be 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
and Calibration
·
The HVSs and their accessories were maintained in good working
condition, such as replacing motor brushes routinely and checking electrical
wiring to ensure a continuous power supply.
·
HVSs are calibrated at bi-monthly intervals
using GMW-25 Calibration Kit throughout all stages of the impact air quality
monitoring.
·
Calibration
details for the HVSs are provided in Appendix E.
2.7
Dust monitoring was conducted for both 1-hr TSP and 24-hr
TSP at all designated monitoring stations in the month. Air quality monitoring
results and graphical presentations are provided in Appendix F.
1-hour TSP Monitoring
2.8
All measured 1-hour TSP levels complied with the Action and
Limit Levels in the month. A summary of 1-hour TSP monitoring results is presented
in Table 2.4.
Table 2.4 Summary of Impact 1-hour TSP Monitoring Results
|
Monitoring Station |
1-hour TSP (mg/m3) |
Action Level (mg/m3) |
Limit Level (mg/m3) |
No. of Exceedance |
|
|
Range |
Action |
Limit |
|||
|
AM1 |
78.5
– 143.1 |
311.2 |
500.0 |
Nil |
Nil |
|
AM2 |
88.1 – 136.5 |
368.6 |
500.0 |
Nil |
Nil |
24-hour TSP Monitoring
2.9
All measured 24-hour TSP levels complied with the Action and
Limit Levels in the month. A summary of 24-hour TSP
monitoring results is presented in Table 2.5.
Table 2.5 Summary of Impact 24-hour TSP Monitoring Results
|
Monitoring Station |
24-hour TSP (mg/m3) |
Action Level (mg/m3) |
Limit Level (mg/m3) |
No. of Exceedance |
|
|
Range |
Action |
Limit |
|||
|
AM1 |
25.9
– 124.7 |
177.4 |
260.0 |
Nil |
Nil |
|
AM2 |
34.3
– 174.3 |
205.0 |
260.0 |
Nil |
Nil |