3                AIR QUALITY MONITORING

Monitoring Requirements

3.1          In accordance with the Updated EM&A Manual, impact 1-hour TSP and 24-hr TSP monitoring were conducted to monitor the air quality for the Works Contracts. Appendix B shows the established Action/Limit Levels for the air quality monitoring works.

 

3.2          Impact 1-hour TSP monitoring was conducted for at least three times every 6 days, while the impact 24-hour TSP monitoring was conducted for at least once every 6 days at one air quality monitoring station.

 

Monitoring Location

3.3          Impact air quality monitoring was conducted at the monitoring stations under the Works Contracts, as shown in Figure 1 according to Table 1.1 of Updated EM&A Manual. Table 3.1 describes the location of the air quality monitoring station.

 

Table 3.1     Location for Air Quality Monitoring Locations

EP No.

Contract No.

Monitoring Station

Location

EP-468/2013/A

ND/2019/01

KTN-DMS4

Temporary Structure near Fanling Highway (near Pak Shek Au)

Monitoring Equipment

3.4          As the power supply for High Volume Sample (HVS) for TSP monitoring at KTN-DMS 4 was rejected, direct reading dust meter was used to measure both 1-hour and 24-hour average TSP levels:-

Ÿ    The proposal for alternative monitoring equipment (i.e. direct reading dust meter) for TSP monitoring was approved by EPD according to approved Baseline Air Quality Monitoring Report (KTN & FLN NDA); and

Ÿ    Adopt same measurement methodology (i.e. direct reading dust meter) as baseline monitoring for reliable comparison.

3.5          The proposed use of portable direct reading dust meters was submitted to IEC and obtained agreement from the IEC as stated in Section 2.4.5 of the Updated EM&A Manual. 

 

3.6          HVS for 24-hr TSP monitoring will be adopted once secured supply of electricity become available at KTN-DMS 4.

 

3.7          Table 3.2 summarizes the equipment used in the impact air monitoring programme. Copies of calibration certificates are attached in Appendix C.

 

Table 3.2    Air Quality Monitoring Equipment

Monitoring Station

Equipment

Model and Make

Quantity

KTN-DMS4

Dust Monitor

AEROCET-831

1

 

3.8          Meteorological information extracted from ¡§Hong Kong Observatory - Ta Kwu Ling Weather Station¡¨ was proposed as the alternative method to obtain representative wind data. For Ta Kwu Ling Weather Station, it is located nearby the Project site and situated at approximately 15m above mean sea level. The station¡¦s wind data monitoring equipment is set above the existing ground ten meters in compliance with the general setting up requirement. Furthermore, this station also provides other meteorological information, such as the humidity, rainfall, air pressure and temperature etc.

 

3.9          The general weather conditions (i.e. sunny, cloudy or rainy) were recorded by the field staffs during the monitoring day.

Monitoring Parameters, Frequency and Duration

3.10       Table 3.3 summarizes the monitoring parameters and frequencies of impact dust monitoring during the Works Contracts activities. The air quality monitoring schedule for the reporting month is shown in Appendix D.

 

Table 3.3    Impact Dust Monitoring Parameters, Frequency and Duration

Parameters

Frequency

1-hr TSP

Three times/ 6 days

24-hr TSP

Once / 6 days

Monitoring Methodology and QA/QC Procedure

 

1-hour and 24-hour TSP Air Quality Monitoring

 

Instrumentation

 

3.11       Direct reading dust meter was deployed for the air quality monitoring as shown in Table 3.2. 

 

3.12       The measuring procedures of the dust meter are in accordance with the Manufacturer¡¦s Instruction Manual as follows:

 

(AEROCET-831)

       The dust meter is placed at least 1.3 meters above ground.

       Remove the red rubber cap from the AEROCET-831 inlet nozzle.

       Turn on the power switch that is located on the right side of the AEROCET-831.

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

       Then the main counter screen will be displayed.

       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.

       The AEROCET-831 is now checked out and ready for use.

       To switch off the AEROCET-831 power to stop the measuring after sampling.

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

 

Maintenance/Calibration

3.13       The following maintenance/calibration was required for the direct dust meters:

       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.

Results and Observations

3.14       The monitoring results for 1-hour TSP and 24-hour TSP are summarized in Table 3.4 and 3.5, respectively. Detailed monitoring results and graphical presentations of 1-hour and 24-hour TSP monitoring results are shown in Appendix E.

 

Table 3.4         Summary Table of 1-hour TSP Monitoring Results during the

Reporting Month

Monitoring Station

Concentration

(µg/m3)

Action Level, µg/m3

Limit Level, µg/m3

Average

Range

KTN-DMS4

54.8

41.1 ¡V 87.1

297

500

 

Table 3.5     Summary Table of 24-hour TSP Monitoring Results during the

Reporting Month

Monitoring Station

Concentration

(µg/m3)

Action Level, µg/m3

Limit Level, µg/m3

Average

Range

KTN-DMS4

87.2

69.9 ¡V 142.5

192

260

 

3.15       All 1-hour and 24-hour TSP monitoring was conducted as scheduled in the reporting month. No Action/Limit Level exceedances were recorded.

 

3.16       According to our field observations, the major dust source identified at the designated air quality monitoring stations in the reporting month are shown in Table 3.6:

 

Table 3.6     Observation at Dust Monitoring Stations

Monitoring Station

Major Dust Source

KTN-DMS4

Excavation works, Road traffic

Event and Action Plan

3.17       Should project-related non-compliance of the criteria occur, action in accordance with the Action Plan in Appendix I shall be carried out.