2.         AIR QUALITY

 

Monitoring Requirements

 

2.1               In accordance with the Particular Specification of the Project, ET is required to conduct 1-hr and 24-hr TSP monitoring at the temporary CWSF in TKO 137 during the construction and operation periods to ensure the activities in the Project does not generate dust which exceeds the acceptable level. Appendix C shows the Action and Limit Levels for the environmental monitoring works.

 

Monitoring Equipment

 

2.2               High volume samplers (HVS - Model GS-2310 Accu-vol) complete with the appropriate sampling inlets were installed for 24-hr TSP sampling. The HVS is composed of a motor, a filter holder, a flow controller and a sampling inlet and its performance specification complies with USEPA Standard Title 40, Code of Federation Regulations Chapter 1 (Part 50 Appendix B). A portable dust meter was used for the 1-hr TSP monitoring. Table 2.1 summarises the equipment used.

 

Table 2.1         Air Quality Monitoring Equipment

 

Equipment

Model

HVS

GS 2310 Accu-vol system

Calibrator

GMW 25

1-hour TSP Dust Meter

Laser Dust Monitor – Model LD-3

 

Monitoring Parameter, Frequency and Schedule

 

2.3               The monitoring parameters and frequency are summarised in Table 2.2. The monitoring schedule for the reporting period is shown in Appendix D.

 

Table 2.2         Frequency of Air Quality Monitoring

 

Parameters

Frequency

24-hour TSP

Once/week

1-hour TSP

Three times/week

 

Monitoring Locations

 

2.4               Two air quality monitoring stations were selected for 24-hr and 1-hr TSP sampling at TKO 137.

 

2.5               The monitoring station TKO1 was relocated on 16 April 2006. The first monitoring event at the new location was conducted on 18 April 2006. The locations for the air quality monitoring stations are summarised in Table 2.3 and depicted in Figures 2.1.

 

Table 2.3         Air Quality Monitoring Stations

 

Station ID

Identity/Description

TKO1

North Boundary of the CWSF at TKO 137 in Area A

TKO2

Combined Reception & Exit Office in Area B1

 

2.6               During an ad-hoc site meeting with the Engineer, IEC, Contractor and ET on 13 April 2006, ET proposed to cancel the air quality monitoring station TKO1 due to its incapability in reflecting the air quality impact arising from the Project upon the nearby sensitive receiver (i.e. TKO TVB City).  ET will submit a revised EM&A manual with a letter of justification on cancellation of TKO1 for EPD's approval.

 

 

Monitoring Methodology

 

24-hour TSP Monitoring

 

Operating/Analytical Procedures

 

2.7               Operating/analytical procedures for the operation of HVS are as follows:

 

·         The sampler was placed on a horizontal platform with appropriate supporting structure such that:

 

-          the filter was at least 2.5 meters above ground.

-          no two samplers were placed less than 2 metres 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 metres separation from walls, parapets and penthouses was required for the rooftop samplers.

-          a minimum of 2 metres separation from any supporting structure, measured horizontally was required.

-          airflow around the sampler was unrestricted.

-          no furnaces or incineration flues were operating near the sampler.

-          the sampler was more than 20 metres from the dripline.

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

 

·         Prior to the commencement of the dust sampling, the flow rate of the high volume sampler 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.

 

·         For TSP sampling, fibreglass filters (G810) were used [Note: these filters have a collection efficiency of > 99% for particles of 0.3 mm diameter].

 

·         After sampling, the filter was transferred from the filter holder of the HVS to a sealable plastic bag and sent to the laboratory for weighing. The elapsed time was also recorded.

 

·         Before weighing, all filters were conditioned for 24 hours before weighing under temperature of 25°C ±3°C and the relative humidity (RH) < 50% ±5%, preferably 40%.

 

·         All measurement procedures in section 4.3 of the EM&A Manual were followed during the reporting period.

 

            Maintenance

 

2.8               Proper maintenance would be provided for the HVS:

 

·         The HVS motors and their accessories have been properly maintained. Appropriate maintenance such as routine motor brushes replacement (time interval for replacement is about 500 hours) and electrical wiring checking have been conducted to ensure that the equipment and necessary power supply were in good working condition.

1-hour TSP Monitoring

 

            Measuring Procedures

 

2.9               The measuring procedures of the 1-hour dust meter were 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.

 

·         All measurement procedures in section 4.3 of the approved EM&A Manual were followed during the impact monitoring period.

 

            Maintenance

 

2.10            Air suction inlet was normally closed unless in operation. Regular cleaning of the air suction inlet was provided.

 

Wind Data

 

2.11            Historically, the meteorological data for Fill Bank operations at the site was obtained from the in-situ wind station for TKO 137 under previous contracts. Therefore, such practice would be maintained to ensure consistence of meteorological data for the contract in the Fill Bank.

 

Calibration Details

 

24-hour TSP Monitoring

 

2.12            The HVS was calibrated upon installation on site and prior to commissioning. Subsequent calibration would be provided at 2-month intervals using GMW-25 Calibration Kit. The flow rate of the HVS with mass flow controller was calibrated using an orifice calibrator. Five-point calibration was adopted.

 

2.13            Both HVS were calibrated on 6 April 2006. Calibration details are provided in Appendix E.

 

1-hour TSP Monitoring

 

2.14            The 1-hour TSP meter was checked at 3-month intervals to confirm normal operation of the equipment and calibrated at 1-year interval throughout all stages of the air quality impact monitoring.

 

2.15            The 1-hour TSP meter was calibrated on 18 June 2005 and the next calibration will be conducted by 17 June 2006.

 

                Results and Observations

 

2.16            In the reporting month, all the 1-hr and 24-hr TSP monitoring events were carried out in accordance with the schedule, one 24-hour TSP additional monitoring was conducted on 6 April 2006 at monitoring station TKO1. The actual monitoring program for April 2006 is presented in Appendix D. All monitoring data and graphical presentations of the monitoring results are provided in Appendix F. Table 2.4 summarises the average of three 1-hr TSP monitoring results and Table 2.5 lists out all the 24-hr TSP monitoring results.

 

Table 2.4         Summary of 1-hr TSP Monitoring Results

 

Date

TKO1

TKO2

Monitoring Status

Averaged

1-hr TSP

(mg/m3)

Exceedance

Averaged

1-hr TSP

(mg/m3)

Exceedance

06/04

181.7

X

203.0

X

Regular

12/04

210.2

X

194.9

X

Regular

19/04

205.8

X

214.4

X

Regular

29/04

189.4

X

192.2

X

Regular

1. L – limit level exceedance; A - action level exceedance; X – not an exceedance

 

Table 2.5         Summary of 24-hr TSP Monitoring Results

 

Date

TKO1

TKO2

Monitoring Status

24-hr TSP

(mg/m3)

Exceedance1

24-hr TSP

(mg/m3)

Exceedance1

04/04

395.6

L

283.3

L

Regular

06/04

119.5

X

--

--

Additional

11/04

62.8

X

63.5

X

Regular

18/04

134.9

X

137.3

X

Regular

28/04

51.7

X

22.1

X

Regular

1.     L – limit level exceedance; A - action level exceedance; X – not an exceedance

 

 

2.17            There was no exceedance in 1-hr TSP monitoring in the reporting month. Two limit level exceedances in 24-hr TSP monitoring were recorded at TKO1 and TKO2 in the reporting month. According to the ET’s on site observation, exceedances were considered to be mainly caused by insufficient dampening along the haul road and for the sorting activities inside the CWSF.

 

2.18            Due to high levels of 24-hr TSP recorded on 24 and 30 March 2006 (exceeding previous range from 69.3mg/m3 to 569.15mg/m3), additional monitoring for 24-hr TSP at TKO1 was conducted on 6 April 2006. The Contractor was advised to provide water sprinklers for all dumping, sorting and transferring activities on site and for all haul roads inside the site. The Contractor agreed to review the dust suppression measures on site.

 

2.19            Besides the construction activities inside the Project site, other potential dust sources included the dump truck traffic and excavation activities inside the Fill Bank of TKO 137 and PBR2 CWSF.

 

2.20            Wind data, including wind speed and wind direction, are annexed in Appendix G.