2.            AIR QUALITY

 

2.1         Monitoring Requirement

 

In accordance with the approved EM&A Manuals, 24-hour Total Suspended Particulates (TSP) level at the designated air quality monitoring station is required. Impact 24-hour TSP monitoring should be carried out at least once every 6 days. In case of complaints, 1-hour TSP monitoring should be carried out at least 3 times per 6 days when the highest dust impacts are likely to occur. The Action and Limit Levels of the air quality monitoring are given in Appendix C.

 

2.2         Monitoring Equipment

 

The 24-hour TSP air quality monitoring was performed using High Volume Air Samplers (HVS) located at each of the designated monitoring station. Portable TSP Monitors would be used in case of complaints for 1-hour TSP monitoring.

 

Table 2.1 summarizes the equipment used in air quality monitoring.

 

2.3         Monitoring Methodology

 

2.3.1     24-hour TSP air quality monitoring

 

HVS Installation

 

The following guidelines were adopted during the installation of HVS:

 

n   Sufficient support is provided to secure the samplers against gusty wind.

n   No two samplers are placed less than 2 meters apart.

n   The distance between the sampler and an obstacle, such as buildings, is at least twice the height that the obstacle protrudes above the sampler.

n   A minimum of 2 meters of separation from walls, parapets and penthouses is required for rooftop samples.

n   A minimum of 2 meters separation from any supporting structure, measured horizontally is required.

n   No furnaces or incineration flues are nearby.

n   Airflow around the samplers is unrestricted.

n   The samplers are more than 20 meters from the drip line.

n   Any wire fence and gate, to protect the sampler, should not cause any obstruction during monitoring.

 

Filters Preparation

 

Fiberglass filters (provided by the HOKLAS accredited laboratory) shall be used (Note: these filters have a collection efficiency of larger than 99% for particles of 0.3 µm diameter). A HOKLAS accredited laboratory (ALS Technichem (HK) Pty Ltd.) is responsible for the preparation of 24-hr conditioned and pre-weighed filter papers for monitoring team.

 

All filters are equilibrated in the conditioning environment for 24 hours before weighing. The conditioning environment temperature is around 25°C and not variable by more than ±3°C; the relative humidity (RH) is < 50% and not variable by more than ±5%. A convenient working RH is 40%.

 

Operating / Analytical Procedures

 

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

 

n   Prior to the commencement of the dust sampling, the flow rate of the HVS are properly set (between 0.6 m3/min and 1.7 m3/min) in accordance with the EM&A manual. The flow rate shall be indicated on the flow rate chart.

n   The power supply shall be checked to ensure the samplers worked properly.

n   On sampling, the samplers shall be operated for 5 minutes to establish thermal equilibrium before placing any filter media at the designated air quality monitoring station.

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

n   The filter shall be aligned on the screen so that the gasket formed an airtight seal on the outer edges of the filter. Then the filter holding frame is tightened to the filter holder with swing bolts. The applied pressure should be sufficient to avoid air leakage at the edges.

n   The shelter lid shall be closed and secured with the aluminum strip.

n   The timer is then programmed. Information shall be 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).

n   After sampling, the filter shall be removed and sent to laboratory for weighing. The elapsed time is also recorded.

n   Before weighing, all filters are 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%. Weighing results are returned to MCL for further analysis of TSP concentrations collected by each filter.

 

2.3.2     1-hour TSP air quality monitoring

 

Operating / Analytical Procedures

 

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

 

§  Pull up the air sampling inlet cover

§  Change the Mode 0 to BG once

§  Push Start/Stop switch once

§  Turn the knob to SENSI.ADJ and press it

§  Push Start/Stop switch once

§  Return the knob to the position MEASURE slowly

§  Push the timer set switch to set measuring time

§  Remove the cap and make a measurement

 

2.4         Maintenance / Calibration

 

2.4.1     24-hour TSP air quality monitoring

 

The following maintenance / calibration are required for the HVS:

 

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

n   All HVS shall be calibrated (five point calibration) using Calibration Kit upon installation and thereafter in every 3 months.

n   A copy of the calibration certificates for the HVS and calibrator are provided in

Appendix D.

 

2.4.2     1-hour TSP air quality monitoring

 

The portable TSP monitor should be calibrated at 1 year intervals

 

2.5         Monitoring Locations

 

2.5.1     According to the EM&A Manual, three air quality monitoring locations, namely KTD1, KTD2 and KER1, are covered by this Contract within the South Apron Area of Former Kai Tak Airport. The other two air quality monitoring locations, which are identified in Cha Kwo Ling area, are farther than 500m away from the site boundary and thus not covered by this Contract. The monitoring works in Cha Kwo Ling area are covered by other Contract(s) respectively.

 

2.5.2      According to the approved alternative baseline air quality and noise monitoring locations (EPD reference: () in EP2/K19/A/21 pt.5), the original monitoring locations (KTD1, KTD2 and KER1) are proposed to be replaced by alternative monitoring locations (KTD1a, KTD2a and KER1a) for air quality monitoring.

 

2.5.3      According to the approved relocation of monitoring location KER1a (EPD reference: () in EP2/K19/A/21 pt.5), the monitoring location KER1a are proposed to be relocated by alternative monitoring locations KER1b for air quality monitoring.

2.5.4      According to the approved relocation of monitoring location KTD2a (EPD reference: () in EP2/K19/A/21 pt.6), the monitoring location KTD2a are proposed to be relocated by alternative monitoring locations KTD2b for air quality monitoring.

 

2.5.5      The most updated locations are summarized in Table 2.2 and shown in Figure 2.

 

2.6         Results and Observations

 

2.6.1     The schedule of air quality monitoring in reporting month is provided in Appendix E.     

 

2.6.2     No Action / Limit Level exceedance was recorded for 24-hr TSP at KTD1a, KTD2b and KER1b in the reporting month.

 

2.6.3     No complaint of air quality was received. Therefore, no impact 1-hour TSP monitoring was conducted in the reporting month.

 

2.6.4     During the reporting month, major dust sources including loading and unloading of C&D wastes, vehicles movement were observed in the site. Non-project related construction activities at the nearby construction site and road traffic along Shing Cheong Road, Cheung Yip Street and the Kwun Tong By-pass were observed. The above factors may affect the monitoring results.

 

2.6.5     The weather conditions during the monitoring are provided in Appendix K.

 

2.6.6     The monitoring data of 24-hr TSP are summarized in Table 2.3. Detailed monitoring data are presented in Appendix F.

 

2.6.7     The Event and Action Plan for air quality is given in Appendix H.

 

2.7          Comparison of 24-hr TSP Monitoring Results with EIA Predictions

 

2.7.1     The monitoring data of 24-hr TSP was compared with the EIA predictions as summarized in Table 2.4.

 

2.7.2     The 24-hour TSP monitoring results at KTD1a and KER1b were below the Predicted Maximum 24-hr TSP concentration in the approved Environmental Impact Assessment (EIA) Report and no Action / Limit Level exceedance was recorded in the reporting period.