2.            AIR QUALITY

 

2.1         Monitoring Requirement

 

2.1.1      In accordance with the approved EM&A Manuals, 24-hour Total Suspended Particulates (TSP) monitoring 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.

 

2.2         Monitoring Methodology

 

2.2.1      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.

 

2.2.2      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

 

2.3         Monitoring Locations

 

2.3.1      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 Contract No. ED/2018/04.

 

2.3.2       According to the approved alternative baseline air quality and noise monitoring locations (EPD reference: 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.

 

2.3.3       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 location KER1b for air quality monitoring.

2.3.4       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 location KTD2b for air quality monitoring.

 

2.3.5       According to the approved relocation of monitoring location KTD2b (EPD reference: () in EP2/K19/A/21 pt.7), the monitoring location KTD2b are proposed to be relocated by alternative monitoring location KTD2c for air quality monitoring.

 

2.3.6      As informed by the ET of Contract No. ED/2018/04, the monitoring location KTD1a and KER1b have been relocated to KTD1 and KER1 for air monitoring on 3 August 2020.

 

2.3.7       The locations are summarized in Table 2.1 and shown in Figure 2.

 

Table 2.1   Location of Air Quality Monitoring Station

Monitoring Station

Location

KTD1

Centre of Excellence in Paediatrics (Rooftop of Children’s Hospital)

KTD1a

Centre of Excellence in Paediatrics (Children’s Hospital)

KTD2a

G/IC Zone next to Kwun Tong Bypass(Future Hospital at Site 3C1)

KTD2b

G/IC Zone next to Kwun Tong Bypass (Next to the site of the New Acute Hospital)

KTD2c

G/IC Zone next to Kwun Tong Bypass (Next to the Kowloon Bay Sewage Interception Station)

KER1

Future Residential Development at Kerry Godown

KER1a

Site Boundary at Cheung Yip Street

KER1b

Site Boundary at Cheung Yip Street, close to the open space car park area

 

2.4         Results and Observations

 

Baseline Monitoring

 

2.4.1      The baseline air quality monitoring results established was used for the Project (from 20 January 2016 to 3 February 2016) and derive the Action and Limit Levels. The graphical presentations for baseline air quality monitoring over the project period are shown in Appendix C.

 

Impact Monitoring

 

2.4.2      The graphical presentations for impact air quality monitoring in the reporting period are shown in Appendix D.

 

2.4.3      Total 17 Action Level and 2 Limit Level exceedance were recorded in the reporting period. Base on the investigation, the occasional exceedances were non-project related. In general, the monitoring parameters were within the range of the baseline levels.