2. AIR QUALITY

Monitoring Requirements

2.1 In accordance with the EM&A Manual, 1-hour and 24-hour TSP levels at 2 air quality monitoring stations were established. Impact 1-hour and 24-hour TSP monitoring was conducted for at least once every 7 days during the construction phase of the Project. The Action and Limit level of the air quality monitoring is provided in Appendix D.

Monitoring Equipment

2.2 24-hour TSP air quality monitoring was performed using High Volume Sampler (HVS) located at each designated monitoring station. The HVS meets all the requirements of the EM&A Manual. Portable direct reading dust meters were used to carry out the 1-hour TSP monitoring. Table 2.1 summarises the equipment used.

Table 2.1 Air Quality Monitoring Equipment

Equipment	Model
High Volume Sampler	GS 2310 Accu-vol system
Calibrator	GMW 25
1-hour TSP Dust Meter	Laser Dust Monitor – Model LD-3

Monitoring Parameters, Frequency and Duration

2.3 Table 2.2 summarizes the monitoring parameters, frequency and duration of impact TSP monitoring.

Table 2.2 Air Quality Monitoring Parameters, Frequency and Duration

Monitoring Station	Parameter	Frequency and Duration
CA1 & CA2	24-hour TSP	At least once every 7 days
CA1 & CA2	1-hour TSP	At least 3 times every 7 days

Monitoring Locations

2.4 Both monitoring stations were set up at the proposed locations in accordance with EM&A Manual. Table 2.3 describes details of the two monitoring stations. The monitoring locations are shown in Figure 2.1.

Table 2.3 Locations of Air Quality Monitoring Stations

Monitoring Station	Identity / Description
CA1	Access road to Po Shan Mansions
CA2	Podium of Hamilton Court

2.5 As requested by the Management Office of the air sensitive receiver Po Shan Mansions, the monitoring station CA1 was relocated to an adjacent location closer to the site, which is still located along the access road to Po Shan Mansions, on 24 April 2008.

Monitoring Methodology

24-hour TSP Monitoring

Installation

2.6 The HVS was installed in the vicinity of the air sensitive receivers. The following criteria were considered in the installation of the HVS.

· A horizontal platform with appropriate support to secure the sampler against gusty wind was provided.

· The distance between the HVS and any obstacles, such as buildings, was at least twice the height that the obstacle protrudes above the HVS.

· A minimum of 2 meters separation from walls, parapets and penthouse was required for rooftop sampler.

· No furnace or incinerator flues were nearby.

· Airflow around the sampler was unrestricted.

· Permission was obtained to set up the samplers and to obtain access to the monitoring stations.

· A secured supply of electricity is needed to operate the samplers.

Preparation of Filter Papers

· Glass fibre filters, G810 were labeled and sufficient filters that were clean and without pinholes were selected.

· 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%.

· ALS Technichem (HK) Pty Ltd. has comprehensive quality assurance and quality control programmes.

Field Monitoring

· The power supply was checked to ensure the HVS works properly.

· The filter holder and the area surrounding the filter were cleaned.

· The filter holder was removed by loosening the four bolts and a new filter, with stamped number upward, on a supporting screen was aligned carefully.

· The filter was properly aligned on the screen so that the gasket formed an airtight seal on the outer edges of the filter.

· The swing bolts were fastened to hold the filter holder down to the frame. The pressure applied should be sufficient to avoid air leakage at the edges.

· Then the shelter lid was closed and was secured with the aluminum strip.

· The HVS was warmed-up for about 5 minutes to establish run-temperature conditions.

· A new flowrate record sheet was set into the flow recorder.

· The range specified in the EM&A Manual was between 0.6-1.7 m³/min.

· The programmable timer was set for a sampling period of 24 hrs + 1 hr, and the starting time, weather condition and the filter number were recorded.

· The initial elapsed time was recorded.

· At the end of sampling, the sampled filter was removed carefully and folded in half length so that only surfaces with collected particulate matter were in contact.

· It was then placed in a clean plastic envelope and sealed.

· All monitoring information was recorded on a standard data sheet.

· Filters were sent to ALS Technichem (HK) Pty Ltd. for analysis.

Maintenance and Calibration

· The HVS and its accessories are maintained in good working condition, such as replacing motor brushes routinely and checking electrical wiring to ensure a continuous power supply.

· HVSs are calibrated using GMW-25 Calibration Kit prior to the commencement of baseline air quality monitoring, and will be calibrated at bi-monthly intervals throughout all stages of the impact monitoring.

· Calibration records are shown in Appendix E.

1-hour TSP Monitoring

Measuring Procedures

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

· Set POWER to “ON”, push BATTERY button, make sure that the meter’s indicator is in the range with a red line and allow the instrument to stand for about 3 minutes (Then, the air sampling inlet has been capped).

· Push the knob at MEASURE position.

· Push “O-ADJ” button. (Then meter’s indication is 0).

· Push the knob at SENSI ADJ position and set the meter’s indication to S value described on the Test Report using the trimmer for SENSI ADJ.

· Pull out the knob and return it to MEASURE position.

· Push “START” button.

Maintenance and Calibration

· The 1-hour TSP meter would be checked at 3-month intervals and calibrated at 1-year intervals throughout all stages of the air quality baseline monitoring. Calibration records are shown in Appendix E.

Monitoring Results

2.8 The monitoring results for 1-hour TSP and 24-hour TSP are summarized in Table 2.4 and 2.5 respectively and the monitoring results are provided in Appendix F.

Table 2.4 Summary of 1-hour TSP Monitoring Results During Reporting Period

	Average (mg/m³)	Range (mg/m³)	Action Level (mg/m³)	Limit Level (mg/m³)
CA1	84.2	77.2 – 93.3	309.3	500
CA2	82.2	77.7 – 88.7	319.6	500

Table 2.5 Summary of 24-hour TSP Monitoring Results During Reporting Period

	Average (mg/m³)	Range (mg/m³)	Action Level (mg/m³)	Limit Level (mg/m³)
CA1	66.1	46.9 – 93.8	166.8	260
CA2	74.8	35.3 – 122.5	187.0	260

2.9 Air quality monitoring was carried out for both 1-hour TSP and 24-hour TSP at all the monitoring stations in the reporting month. 24-hour TSP monitoring at CA1 (Po Shan Mansions) was temporary suspended from 10 April 2008 due to the complaint received from the Management Office regarding the noise generated from the HVS during operation. The HVS was relocated to an adjacent location closer to the site on 24 April 2008 and the 24-hour TSP monitoring resume on the same day. Thus, no 24-hour TSP monitoring was carried out on 10, 16 and 22 April 2008.

2.10 The air quality monitoring results, in terms of 1-hour TSP and 24-hour TSP, were below the action and limit level at both monitoring locations in the reporting month. The event action plan is annexed in Appendix G.

2.11 Weather information including wind speed and wind direction is annexed in Appendix H. The information was obtained from Hong Kong Observatory Victoria Peak Automatic Weather Station and Central Pier Anemometer Station.