3.              AIR QUALITY

Monitoring Requirements

 

3.1              According to EM&A Manual of the Project, 1-hour and 24-hour TSP monitoring are required to monitor the air quality. For regular impact monitoring, a sampling frequency of at least once in every six days shall be undertaken at all of the monitoring stations for 24-hour TSP monitoring. For 1-hour TSP monitoring, the sampling frequency of at least three times in every six days shall be undertaken when the highest dust impact occurs. Appendix A shows the established Action/Limit Levels for the environmental monitoring works.

Monitoring Locations

 

3.2              Six designated monitoring stations were selected for air quality monitoring programme. Table 3.1 describes the air quality monitoring locations, which are also depicted in Figure 2.

 

Table 3.1       Locations for Air Quality Monitoring

Monitoring Stations

Location

Location of Measurement

AM1

Tin Hau Temple

Ground Level

AM2

Sai Tso Wan Recreation Ground

Ground Level

AM3

Yau Lai Estate Bik Lai House

Rooftop (41/F)

AM4(1)

Sitting-out Area at Cha Kwo Ling Village

Ground Level

AM4(A)(2) (*)

Cha Kwo Ling Public Cargo Working Area Administrative Office

Rooftop (3/F)

AM5(A)(*)

Tseung Kwan O DSD Desilting Compound

Ground Level

AM6(A) (*)

Park Central, L1/F Open Space Area

1/F

 Remarks: (1) For 1-hour TSP monitoring; (2) For 24-hour TSP monitoring

(*) Air quality monitoring at designated station AM4(24-hr TSP), AM5 and AM6 was rejected by the premise owners. Therefore, baseline and impact air quality monitoring works were carried out at alternative air quality monitoring stations AM4(A) (24-hr TSP only), AM5(A) and AM6(A) respectively.

Monitoring Equipment

3.3              High Volume Samplers (HVS) were used to carry out 24-hour TSP monitoring. Direct reading dust meter were also used to measure 1-hour average TSP levels. The 1-hour sampling was determined periodically by HVS to check the validity and accuracy of the results measured by direct reading method.

 

3.4              Wind data monitoring equipment was set at rooftop (about 41/F) of Yau Lai Estate Bik Lai House 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.

 

3.5              Table 3.2 summarizes the equipment to be used in the air quality monitoring.  Copies of calibration certificates are attached in Appendix B.

 


Table 3.2        Air Quality Monitoring Equipment

Equipment

Model and Make

Quantity

Calibrator

TISCH Model: TE-5025A

1

1-hour TSP Dust Meter

Sibata Model No.: LD-3 / LD-3B

1

Met One Instruments Model No.: AEROCET-831

4

Handheld Particle Counter Hal-HPC300 / Hal-HPC301

4

HVS Sampler

TISCH Model: TE-5170

1

GMW Model: GS2310

5

Wind Anemometer

Davis Weather Monitor II, Model no. 7440

1

Davis Weather Stations, Vantage Pro 2, Model No. 6152CUK

0

Monitoring Parameters and Frequency

3.6              Table 3.3 summarizes the monitoring parameters, monitoring period and frequencies of air quality monitoring.

 

Table 3.3        Frequency and Parameters of Air Quality Monitoring

Monitoring Stations

Parameter

Frequency

AM1, AM2, AM3, AM4, AM5(A) and AM6(A)

1-hour TSP

3 times per 6 day

AM1, AM2, AM3, AM4(A), AM5(A) and AM6(A)

24-hour TSP

Once per 6 days

Monitoring Methodology

1-hour TSP Monitoring

Measuring Procedures

3.7              The measuring procedures of the 1-hour dust meter are in accordance with the Manufacturer’s Instruction Manual as follows:

(Model LD3 / LD3B)

Ÿ  The 1-hour dust meter is placed at least 1.3 meters above ground.

Ÿ  Set POWER to “ON” and make sure that the battery level was not flash or in low level.

Ÿ  Allow the instrument to stand for about 3 minutes and then the cap of the air sampling inlet has been released.

Ÿ  Push the knob at MEASURE position.

Ÿ  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.

Ÿ  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.

Ÿ  Information such as sampling date, time, count value and site condition were recorded during the monitoring period.


(AEROCET-531)

Ÿ  The 1-hour dust meter is placed at least 1.3 meters above ground.

Ÿ  Remove the red rubber cap from the AEROCET-531 inlet nozzle.

Ÿ  Turn on the power switch that is located on the right side of the AEROCET-531.

Ÿ  On power up the product intro screen is displayed for 3 seconds. The intro screen displays the product name and firmware version.

Ÿ  Then the main counter screen will be displayed.

Ÿ  Press the START button. Internal vacuum pump start running. After 1 minute the pump will stop and the 0.5µm and 5µm channels will show the cumulative counts of particles larger than 0.5µm and 5µm per cubic foot.

Ÿ  The AEROCET-531 is now checked out and ready for use.

Ÿ  To switch off the AEROCET-531 power to stop the measuring after 1 hour sampling.

Ÿ  Information such as sampling date, time, and display value and site condition were recorded during the monitoring period.

 

(Equipment: Hal Technology; Model no. Hal-HPC300 / Hal-HPC301)

Ÿ  The 1-hour dust meter is placed at least 1.3 meters above ground.

Ÿ  Set POWER to “ON” and make sure that the battery level was not flash or in low level.

Ÿ  Allow the instrument to stand for about 3 minutes and then the cap of the air sampling inlet has been released.

Ÿ  Push the knob at MEASURE position.

Ÿ  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.

Ÿ  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.

Ÿ  Information such as sampling date, time, count value and site condition were recorded during the monitoring period.

Maintenance/Calibration

3.8              The following maintenance/calibration is required for the direct dust meters:

Ÿ  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.

 

24-hour TSP Monitoring

Instrumentation

 

3.9              High volume samplers (HVS) (TISCH Model: TE-5170 and GMW Model: GS2310) completed with appropriate sampling inlets were employed for 24-hour TSP monitoring.  The sampler is composed of a motor, a filter holder, a flow controller and a sampling inlet and its performance specification complied with that required by USEPA Standard Title 40, Code of Federation Regulations Chapter 1 (Part 50).

 


3.10          The positioning of the HVS samplers are as follows:

Ÿ  a horizontal platform with appropriate support to secure the samplers against gusty wind shall be provided;

Ÿ  no two samplers shall be placed less than 2 meter apart

Ÿ  the distance between the sampler and an obstacle, such as buildings, must be at least twice the height that the obstacle protrudes above the sampler;

Ÿ  a minimum of 2 metres of separation from walls, parapets and penthouses is required for rooftop samplers;

Ÿ  a minimum of 2 metres of separation from any supporting structure, measured horizontally is required;

Ÿ  no furnace or incinerator flue is nearby;

Ÿ  airflow around the sampler is unrestricted;

Ÿ  the sampler is more than 20 metres from the dripline;

Ÿ  any wire fence and gate, to protect the sampler, shall not cause any obstruction during monitoring;

Ÿ  permission must be obtained to set up the samplers and to obtain access to the monitoring stations; and

Ÿ  a secured supply of electricity is needed to operate the samplers.

Operating/analytical procedures for the operation of HVS

3.11          Prior to the commencement of the dust sampling, the flow rate of the high volume sampler was properly set (between 1.1 m3/min. and 1.4 m3/min.) in accordance with the manufacturer's instruction to within the range recommended in USEPA Standard Title 40, CFR Part 50.

 

3.12          For TSP sampling, fiberglass filters with a collection efficiency of > 99% for particles of 0.3μm diameter were used.

 

3.13          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 monitoring station.

 

3.14          The filter holding frame was then removed by loosening the four nuts and a weighted and conditioned filter was carefully centered with the stamped number upwards, on a supporting screen.

 

3.15          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.

 

3.16          The shelter lid was closed and secured with the aluminum strip.

 

3.17          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).

 

3.18          After sampling, the filter was removed and sent to the HOKLAS laboratory (Wellab Ltd.) for weighing.  The elapsed time will be also recorded.

 

3.19          Before weighing, all filters was equilibrated in a conditioning environment for 24 hours. 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%.

Maintenance/Calibration

3.20          The following maintenance/calibration is required for the HVS:

Ÿ  The high volume motors and their accessories will be properly maintained. Appropriate maintenance such as routine motor brushes replacement and electrical wiring checking will be made to ensure that the equipment and necessary power supply are in good working condition.

Ÿ  High volume samplers will be calibrated at bi-monthly intervals using TE-5025A Calibration Kit throughout all stages of the air quality monitoring.

Results and Observations

3.21          All 1-hour TSP monitoring was conducted as scheduled in the reporting month. No Action/Limit Level exceedance was recorded.

 

3.22          All 24-hour TSP monitoring was conducted as scheduled in the reporting month. No Action/Limit Level exceedance was recorded.

 

3.23          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 at rooftop of Yau Lai Estate Bik Lai House (41/F). The location is shown in Figure 2. This weather information for the reporting month is summarized in Appendix C.

 

3.24          The monitoring data and graphical presentations of 1-hour and 24-hour TSP monitoring results are shown in Appendix E and Appendix F respectively.

 

3.25          The summary of exceedance record in reporting month is shown in Appendix K. No exceedance was recorded for the air quality monitoring.

 

3.26          According to our field observations, the major dust source identified at the designated air quality monitoring stations are as follows:

 

Table 3.4        Major Dust Source during Air Quality Monitoring

Station

Major Dust Source

AM1 – Tin Hau Temple

Road Traffic at Cha Kwo Ling Road

AM2 – Sai Tso Wan Recreation Ground

N/A

AM3 – Yau Lai Estate Bik Lai House

Road Traffic near Eastern Cross Harbour Tunnel Toll Plaza

AM4 - Sitting-out Area at Cha Kwo Ling Village

Road Traffic at Cha Kwo Ling Road

AM4(A) - Cha Kwo Ling Public Cargo Working Area Administrative Office

Road Traffic at Cha Kwo Ling Road

AM5(A) - Tseung Kwan O DSD Desilting Compound

Vehicle Movement within the Desilting Compound

AM6(A) - Park Central, L1/F Open Space Area

Road Traffic at Po Yap Road