2 AIR QUALITY

Monitoring Requirements

2.1 In accordance with the EM&A Manual, baseline air quality monitoring should be conducted for a period of fourteen days, in terms of 1-hour and 24-hour Total Suspended Particulates (TSP). Monitoring of 1-hour TSP was carried out three times per day while 24-hour TSP was conducted for 14 consecutive days.

Monitoring Equipment

2.2 Both 1-hour TSP monitoring and continuous 24-hour TSP air quality monitoring was performed using High Volume Sampler (HVS) associated with equipment and shelter complied with the specifications stipulated in the EM&A Manual. Table 2.1 summarizes the equipment used in the baseline air quality monitoring programme. Copies of the calibration certificates for the equipment are presented in Appendix A.

Table 2.1 Air Quality Monitoring Equipment

Equipment	Model and Make	Qty.
HVS	Tisch; Model no. TE-5170	1
Laser Dust Monitor	Sibata; Model no. LD3B	2

Monitoring Locations

2.3 Baseline air quality monitoring was conducted at one monitoring station, AM9, as shown in Figure 2. Table 2.2 describes the locations of the air quality monitoring stations.

Table 2.2 Air Quality Monitoring Location

Monitoring Stations	Location of Measurement
AM9 (1-hr & 24-hr TSP)	Work Site Boundary (Near Ngong Shuen Chau Barracks Group 2)

Monitoring Parameters, Frequency and Duration

2.4 Table 2.3 summarizes the monitoring parameters, monitoring period and frequencies of baseline air quality monitoring.

Table 2.3 Frequency and Parameters of Baseline Air Quality Monitoring

Monitoring Stations	Parameter	Period	Frequency
AM9	24-hour TSP	24 hours	Daily for 14 Days
	1-hour TSP	1 hour between 0700-1900	3 times/day for 14 Days

Monitoring Methodology and QA/QC Procedure

2.5 Weather data was recorded during the baseline period and is shown in Appendix D. The air temperature, precipitation and the relative humidity data was obtained and make reference from the Hong Kong Observatory Webpage (Tsing Yi weather station). The general weather conditions (i.e. sunny, cloudy or rainy) were recorded by the field staff¡¦s observation on the monitoring day.

1-hour TSP Monitoring

Measuring Procedures

2.6 The measuring procedures of the 1-hour dust meters were in accordance with the Manufacturer¡¦s Instruction Manual as follows:

¡P Pull up the air sampling inlet cover

¡P Change the Mode 0 to BG with once

¡P Push Start/Stop switch once

¡P Turn the knob to SENSI.ADJ and press it

¡P Push Start/Stop switch once

¡P Return the knob to the position MEASURE slowly

¡P Push the timer set switch to set measuring time

¡P Remove the cap and make a measurement

Maintenance/Calibration

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

¡P Check the meter at a 3-month interval and calibrate the meter at a 1-year interval throughout all stages of the air quality monitoring.

24-hour TSP Monitoring

Instrumentation

2.8 High Volume Sampler (HVS) completed with appropriate sampling inlets was employed for air quality monitoring. Each sampler comprised 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

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

¡P Sufficient support was provided to secure the samplers against gusty wind.

¡P No two samplers were placed less than 2 meters apart.

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

¡P A minimum of 2 meters of separation from walls, parapets and penthouses was required for rooftop samples.

¡P A minimum of 2 meters separation from any supporting structure, measured horizontally was required.

¡P No furnaces or incineration flues were nearby.

¡P Airflow around the sampler was unrestricted.

¡P The samplers were more than 20 meters from the drip line.

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

Filters Preparation

2.10 Fiberglass filters (G810) were used [Note: these filters have a collection efficiency of larger than 99% for particles of 0.3 mm diameter]. A HOKLAS accredited laboratory, Wellab Ltd., was responsible for the preparation of 24-hr conditioned and pre-weighed filter papers for Cinotech¡¦s monitoring team.

2.11 All filters, which were prepared by Wellab Ltd., were equilibrated in the conditioning environment for 24 hours before weighing. The conditioning environment temperature was around 25 ¢XC and not variable by more than ¡Ó3 ¢XC; the relative humidity (RH) was < 50% and not variable by more than ¡Ó5%. A convenient working RH was 40%.

2.12 Wellab Ltd. has a comprehensive quality assurance and quality control programme.

Operating/Analytical Procedures

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

¡P 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.

¡P The power supply was checked to ensure the sampler worked properly.

¡P 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.

¡P 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.

¡P 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.

¡P The shelter lid was closed and secured with the aluminum strip.

¡P 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).

¡P After sampling, the filter was removed and sent to the Wellab Ltd. for weighing. The elapsed time was also recorded.

¡P Before weighing, all filters were equilibrated in a conditioning environment for 24 hours. The conditioning environment temperature should be between 25¢XC and 30¢XC and not vary by more than ¡Ó3¢XC; the relative humidity (RH) should be < 50% and not vary by more than ¡Ó5%. A convenient working RH is 40%. Weighing results were returned to Cinotech for further analysis of TSP concentrations collected by each filter.

Maintenance/Calibration

2.14 The following maintenance/calibration was required for the HVS:

¡P 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.

¡P The HVS was calibrated (five point calibration) using Calibration Kit prior to the commencement of the baseline monitoring.

Results and Observations

Results

2.15 Baseline air quality monitoring was conducted at one monitoring stations, namely AM9, between 30 September 2011 to 14 October 2011 (suspended on 3 October 2011 due to Typhoon Signal No.3 and adverse weather condition). The detailed monitoring schedule is shown in Appendix E.

2.16 The monitoring data are summarized in Tables 2.4 and 2.5. All monitoring data of 1-hour and 24-hour TSP are presented in Appendices B1 and B3 respectively. Graphical presentations of the 1-hour TSP and 24-hour TSP results are shown in Appendices B2 and B4 respectively. Detailed weather conditions during the baseline monitoring period are shown in Appendix D.

Table 2.4 Summary of Baseline 1-hour TSP Monitoring Results

Monitoring Station	Average TSP Concentration, £gg/m^3 (Range)
AM9	104.2 (49.5-152.3)

Table 2.5 Summary of Baseline 24-hour TSP Monitoring Results

Monitoring Station	Average TSP Concentration, £gg/m^3 (Range)
AM9	59.3 (34.2-94.9)

Observations

2.17 The weather was generally cloudy or fine during the baseline monitoring period. The weather conditions were recorded by our field staff during the replacing of filter paper and the maintenance/checking of the Sound Level Meter respectively.

2.18 During the baseline monitoring, no major dust generating activity was identified in the vicinity of the monitoring station.

2.19 No influencing factor that may affect the monitoring results could be identified. Therefore, the baseline air quality monitoring results are considered representative to the ambient air quality conditions of the sensitive receiver.

Action and Limit Levels

2.20 The Action and Limit Levels have been set in accordance with the EM&A Manual, which are summarized in Table 2.6.

Table 2.6 Guidelines for Establishing Action and Limit Levels for Air Quality

Parameters	Action Level	Limit Level
1-hour TSP	¡P If BL ≤ 384 £gg/m^3, AL = (BL ¡Ñ 1.3 + LL) ¡Ò 2 ¡P If BL > 384 £gg/m^3, AL = LL	500 £gg/m^3
24-hour TSP	¡P If BL ≤ 200 £gg/m^3, AL = (BL ¡Ñ 1.3 + LL) ¡Ò 2 ¡P If BL > 200 £gg/m^3, AL = LL	260 £gg/m^3

Remarks:

BL ¡V Baseline Level (Average); AL ¡V Action Level; LL ¡V Limit Level

2.21 Following the above guidelines, the Action and Limit Levels for air quality impact monitoring have been set, as presented in Tables 2.7 and 2.8. According to the EM&A Manual, baseline checking of ambient TSP levels shall be carried out every six months at each monitoring location when no dusty works activities are in operation. If changes in the ambient conditions have arisen, a repeat of the baseline monitoring may be carried out to update the baseline levels and air quality criteria.

Table 2.7 Action and Limit Levels for 1-hour TSP

Location	Action Level, £gg/m^3	Limit Level, £gg/m^3
AM9	318	500

Table 2.8 Action and Limit Levels for 24-hour TSP

Location	Action Level, £gg/m^3	Limit Level, £gg/m^3
AM9	169	260