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 and Figure 2 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-473/2013/A

ND/2019/03

FLN-DMS1[2]

Scattered Village Houses North of Proposed Potential Ecopark

ND/2019/05

FLN-DMS3[3]

House near Tong Hang

EP-466/2013

EP-467/2013/A

EP-468/2013/A

ND/2019/01

KTN-DMS4

Temporary Structure near Fanling Highway (near Pak Shek Au)

EP-468/2013/A

ND/2019/03

Remark:

[1]: Noting that construction phase air quality monitoring at the other proposed monitoring stations (e.g. planned), where access is permitted, will be conducted during the relevant works contract(s).

[2]: Since the distance between monitoring station and site boundary of ND/2019/05 under EP-473/2013/A exceeds 500m. The monitoring station is not applicable to ND/2019/05.

[3]: Since the distance between monitoring station and site boundary of ND/2019/03 under EP-473/2013/A exceeds 500m. The monitoring station is not applicable to ND/2019/03.

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

Manufacturer

Model and Make

Quantity

KTN-DMS4

Dust Monitor

(1-hour and 24-hour TSP)

Met One Instruments

AEROCET-831

3

FLN-DMS1 FLN-DMS3

Dust Monitor

(1-hour TSP)

HVS Sampler (TSP)

(24-hour TSP)

Tisch

TISCH Model: TE-5170

2

 

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.

 

24-hour TSP Air Quality Monitoring

 

Instrumentation

 

(TISCH Model: TE-5170)

 

3.14       High volume Samplers (HVS) completed with appropriate sampling inlets were employed for 24-hour TSP 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).

 

HVS Installation

 

3.15       The following guidelines were adopted during the installation of HVS:

 

       A horizontal platform with appropriate 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.

       Permission and access to the monitoring stations have been obtained to set up the samplers; and

       A secured supply of electricity was provided to operate the samplers.

 

Filters Preparation

 

3.16       Wellab Limited (HOKLAS Registration No.083) is the HOKLAS accredited laboratory and responsible for the preparation of 24-hr conditioned and pre-weighed filter papers for monitoring team. 

3.17       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%.

 

Operating/Analytical Procedures

 

3.18       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 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;

       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 kept in a clean and tightly sealed plastic bag. The filter paper was then be returned to the HOKLAS laboratory (Wellab Ltd.) for reconditioning in the humidity-controlled chamber followed by accurate weighting by an electronic balance with a readout down to 0.1mg. The elapsed time was also recorded; and

       Before weighing, all filters were 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 RH should be < 50% and not vary by more than ±5%.  A convenient working RH is 40%.  Weighing results were returned for further analysis of TSP concentrations collected by each filter.

 

Maintenance/Calibration

 

3.19       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; and

       All HVS were calibrated (five point calibration) using Calibration Kit prior to the commencement of the baseline monitoring and thereafter at bi-monthly intervals.

 

Results and Observations

3.20       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

FLN -DMS1

87.4

65.2-117.9

303

500

FLN -DMS3

85.7

43.1-135.9

301

500

KTN-DMS4

51.4

26.5-68.1

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

FLN -DMS1

38.2

24.1-81.1

150

260

FLN -DMS3

41.4

21.6-86.6

165

260

KTN-DMS4

104.8

68.5-148.8

192

260

 

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

 

3.22       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

FLN -DMS1

Road traffic

FLN -DMS3

Road traffic

KTN-DMS4

Excavation, Road traffic

Event and Action Plan

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