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 shall be conducted to monitor the air quality for the Works Contracts. Appendix B shows the established Action/Limit Level 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 the designated air quality monitoring stations.

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 and Baseline Air Quality Monitoring Report (KTN & FLN NDA).

Alternative Monitoring Station for KTN-DMS4

3.4          As KTN-DMS4 - Temporary structure near Fanling Highway (near Pak Shek Au) is no longer as existing ASR, air quality monitoring station should be relocated to the alternative dust monitoring location according to the updated EM&A Manual, Section 2.6.2. According to Figure 3.1 of Approved EIA report and site visits conducted in June 2022, ASR at near KTN-E70 – Temporary Structure near Fanling Highway near Pak Shek Au is considered as the most representative alternative station KTN-DMS4(B) for air quality monitoring for KTN-DMS4 (i.e. KTNE162).

3.5          The alternative monitoring location KTN-DMS4(B) is agreed by EPD on 17 August 2022. The 1-hr and 24-hrs TSP monitoring commenced starting from 24 August 2022. Table 3.1 describes the location of the air quality monitoring stations.

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/2019/04

ND/2019/05

FLN-DMS3[3]

House near Tong Hang

ND/2019/03

FLN-DMS5[4]

FLN-DMS5A

Noble Hill

Good View New Village

ND/2019/04

EP-466/2013

EP-467/2013/A

EP-468/2013/A

ND/2019/01

KTN-DMS4 /

KTN-DMS4(B)[5]

Temporary Structure near Fanling Highway (near Pak Shek Au)

EP-468/2013/A

ND/2019/03

Remarks:

[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 construction phase of 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 and ND/2019/04 under EP-473/2013/A exceeds 500m, the monitoring station is not applicable to ND/2019/03 and ND/2019/04.

[4]: 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

[5] KTN-DMS4(B) commenced starting from 24 August 2022 as an alternative monitoring station of KTN-DMS4.

Monitoring Equipment

3.6          As the power supply for High Volume Sampler (HVS) for TSP monitoring at FLN-DMS 5A, KTN-DMS 4 and KTN-DMS 4(B) were rejected, direct reading dust meter was used to measure both 1-hour and 24-hour TSP levels:-

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

Ÿ    Same measurement methodology (i.e. direct reading dust meter) was adopted as baseline monitoring for a reliable comparison.

 

3.7          The proposed use of portable direct reading dust meters was also submitted to IEC and agreement was obtained from the IEC in accordance with Section 2.4.5 of the Updated EM&A Manual. 

3.8          HVS for 24-hour TSP monitoring will be adopted once secured supply of electricity become available at FLN-DMS 5A and KTN-DMS 4(B).

3.9          Table 3.2 summarises 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

FLN-DMS5

FLN-DMS5A

KTN-DMS4

KTN-DMS4(B)

Dust Monitor

(1-hour and 24-hour TSP)

Met One Instruments

AEROCET-831

5

FLN-DMS1

FLN-DMS3

Dust Monitor

(1-hour TSP)

HVS Sampler (TSP)

(24-hour TSP)

Tisch

TISCH Model:

TE-5170

1

 

3.10       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 10 meters in compliance with the general setting up requirements. Furthermore, this station also provides other meteorological information, such as humidity, rainfall, air pressure and temperature etc.

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

Monitoring Parameters, Frequency and Duration

3.12       Table 3.3 summarises 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-hour TSP

Three times/ 6 days

24-hour TSP

Once / 6 days

Monitoring Methodology and QA/QC Procedure

1-hour and 24-hour TSP Air Quality Monitoring

Instrumentation

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

3.14       The measuring procedures of the dust meters were in accordance with the Manufacturer’s Instruction Manual as follows:

(AEROCET-831)

       Place the 1-hour dust meter at least 1.3 meters above ground.

       Press and hold the Power key momentarily to power on the unit and make sure that the battery level was not flash or in low level.

       Allow the instrument to stand for about 3 second to display the Sample Screen minutes.

       Press the START / STOP key to run the internal vacuum pump for 1 minute and be ready to use.

       Use the select dial to select the PM range and press the START / STOP key to start a measurement.

       Finally, push the START/STOP key to stop the measurement after 1 hour sampling.

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

       All data were recorded in the data logger for further data processing.

Maintenance/Calibration

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

       Check and calibrate the meters 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)

3.16       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

 

3.17       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.

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

Filters Preparation

3.18       Wellab Limited (HOKLAS Registration No. HOKLAS083) is a HOKLAS accredited laboratory and responsible for the preparation of 24-hour conditioned and pre-weighed filter papers for the monitoring team. 

3.19       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

3.20       Operating/analytical procedures for the air quality monitoring were highlighted as follows:

       Prior to the commencement of 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.  The filter holding frame was then 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 returned to the HOKLAS accredited 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 did not vary by more than ±3°C; the RH should be < 50% and did 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

3.21       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 conditions; and

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

Results and Observations

3.22       The monitoring results for 1-hour TSP and 24-hour TSP are summarised in Tables 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

74.5

51.0 – 107.8

303

500

FLN-DMS3

71.2

54.1 – 93.6

301

500

FLN-DMS5

41.7

17.5 – 97.3

279

500

KTN-DMS4

49.1

22.1 – 93.8

297

500

KTN-DMS4(B)

65.2

45.8 – 96.6

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

51.5

24.5 – 86.5

150

260

FLN-DMS3

39.5

22.1 – 80.3

165

260

FLN-DMS5A

70.2

36.3 – 123.8

153

260

KTN-DMS4

70.1

52.4 – 96.1

192

260

KTN-DMS4(B)

81.5

49.8 – 113.2

192

260

 

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

3.24       According to our field observations, the major dust sources 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 Sources

FLN DMS1

Mobile crane, Excavator, piling, road traffic

FLN-DMS3

Excavator, piling, mobile crane, road traffic

FLN-DMS5

Road traffic

KTN-DMS4

Excavator, piling, mobile crane, dump truck, road traffic

KTN-DMS4(B)

Excavator, piling, mobile crane, dump truck, road traffic

Event and Action Plan

3.25       Should any non-compliance of the criteria occur, actions in accordance with the Event/Action Plan in Appendix N shall be carried out.