4 AIR QUALITY

Introduction

4.1 Potential air quality impact arising from the construction works would mainly be related to construction dust from excavation, materials handling, spoil removal and wind erosion. As construction dust is the prime concern, monitoring should be carried out to evaluate the dust impact during the construction phase. Total Suspended Particulates (TSP) monitoring and site audit are recommended to confirm that the recommended mitigation measures are properly implemented.

4.2 In this section, the requirements, methodology, equipments, monitoring locations and criteria for the monitoring and audit of air quality impact during the construction phase of the Project are presented.

Monitoring Parameters and Equipment

4.3 Monitoring and audit of the TSP levels should be carried out by the ET to ensure that any deteriorating air quality could be readily detected and timely action taken to rectify the situation.

4.4 One-hour and 24-hour TSP levels should be measured to indicate the impacts of construction dust on air quality. The TSP levels should be measured by following the standard method as set out in High Volume Method for Total Suspended Particulates, Part 50 Chapter 1 Appendix B, Title 40 of the Code of Federal Regulations of the USEPA (hereinafter referred to as “HVS method”).

4.5 All relevant data including temperature, pressure, weather conditions, elapsed-time meter reading for the start and stop of sampler, identification and weight of the filter paper, and other special phenomena and work progress of the concerned site, etc, should be recorded down in detail. A sample data sheet is shown in Appendix B3.

4.6 High volume sampler (HVS) in compliance with the following specifications should be used for carrying out the 1-hour and 24-hour monitoring:

(i) 0.6 - 1.7 m³ per minute (20 - 60 standard cubic feet per minute) adjustable flow range;

(ii) equipped with a timing / control device with ± 5 minutes accuracy for 24 hours operation;

(iii) installed with elapsed-time meter with ± 2 minutes accuracy for 24 hours operation;

(iv) capable of providing a minimum exposed area of 406 cm² (63 in²);

(v) flow control accuracy: ± 2.5% deviation over 24-hour sampling period;

(vi) equipped with a shelter to protect the filter and sampler;

(vii) incorporated with an electronic mass flow rate controller or other equivalent devices;

(viii) equipped with a flow recorder for continuous monitoring;

(ix) provided with a peaked roof inlet;

(x) incorporated with a manometer;

(xi) able to hold and seal the filter paper to the sampler housing at horizontal position;

(xii) easy to change the filter; and

(xiii) capable of operating continuously for 24-hour period.

4.7 The ET should be responsible for the provision of the monitoring equipment. He should provide sufficient number of HVS or direct reading dust meter with appropriate calibration kit for carrying out the baseline, regular impacts monitoring and ad-hoc monitoring. The HVSs should be equipped with an electronic mass flow controller and be calibrated against a traceable standard at regular intervals, in accordance with requirements stated in the manufacturers operating manual and as described below. All the equipment, calibration kit, filter papers, etc, should be clearly labelled.

4.8 Initial calibration of HVSs with mass flow controller should be conducted upon installation and thereafter at bi-monthly intervals. The transfer standard should be traceable to the internationally recognized primary standard and be calibrated annually. The calibration data should be properly documented for future reference by the IEC. All the data should be converted into standard temperature and pressure condition.

4.9 The flow-rate of the sampler before and after the sampling exercise with the filter in position should be verified to be constant and be recorded on the data sheet as shown in Appendix B3.

4.10 If the ET Leader proposes alternative dust monitoring equipment / methodology (e.g. direct reading methods) after this manual is issued, the ET should submit sufficient information to the IEC to prove that the instrument is capable of achieving a comparable result to the HVS. The instrument should also be calibrated regularly, and the 1-hour sampling should be determined periodically by the HVS to check the validity and accuracy of the results measured by direct reading method.

4.11 Wind data monitoring equipment should also be provided and set up for logging wind speed and wind direction near the dust monitoring locations. The equipment installation location should be proposed by the ET and agreed with the IEC. For installation and operation of wind data monitoring equipment, the following points should be observed:

(i) The wind sensors should be installed 10m above ground so that they are clear of obstructions or turbulence caused by buildings.

(ii) The wind data should be captured by a data logger. The data should be downloaded for analysis at least once a month.

(iii) The wind data monitoring equipment should be re-calibrated at least once every six months.

(iv) Wind direction should be divided into 16 sectors of 22.5 degrees each.

4.12 In exceptional situations, the ET may propose alternative methods to obtain representative wind data upon approval from the ER and agreement from the IEC.

Laboratory Measurement / Analysis

4.13 A clean laboratory with constant temperature and humidity control, and equipped with necessary measuring and conditioning instruments to handle the dust samples collected, should be available for sample analysis, and equipment calibration and maintenance. The laboratory should be HOKLAS accredited.

4.14 If a site laboratory is set up or a non-HOKLAS accredited laboratory is hired for carrying out the laboratory analysis, the laboratory equipment should be approved by the ER and the measurement procedures should be witnessed by the IEC. Any measurement performed by the laboratory should be demonstrated to the satisfaction of the ER and IEC. IEC should regularly audit to the measurement performed by the laboratory to ensure the accuracy of measurement results. The ET Leader should provide the ER with one copy of the Title 40 of the Code of Federal Regulations, Chapter 1 (Part 50), Appendix B for his reference.

4.15 Filter paper of size 8” x 10” should be labeled before sampling. It should be a clean filter paper with no pinholes, and should be conditioned in a humidity-controlled chamber for over 24-hours and be pre-weighed before use for the sampling.

4.16 After sampling, the filter paper loaded with dust should be kept in a clean and tightly sealed plastic bag. The filter paper should then be returned to the laboratory for reconditioning in the humidity-controlled chamber followed by accurate weighing by an electronic balance with readout down to 0.1 mg. The balance should be regularly calibrated against a traceable standard.

4.17 All the collected samples should be kept in a good condition for 6 months before disposal.

Proposed Dust Monitoring Stations

4.18 The worst affected locations in the vicinity of the construction activities of the Project identified for dust monitoring are listed in Table 4.1 and shown in Figure Nos. NEX2213/C/331/ENS/M62/530.

Table 4.1 Proposed Dust Monitoring Locations

Identification No.	ASR ID in EIA Report	Air Monitoring Location
AM1	CHA4	Royal Hong Kong Yacht Club

4.19 The status and locations of air quality sensitive receivers may change after this manual is issued. If this happens, the ET Leader should propose updated monitoring locations and seek approval from ER and agreement from the IEC and EPD.

4.20 When alternative monitoring locations are proposed, the monitoring locations should be chosen based on the following criteria:

(i) Monitoring at sensitive receivers close to the major site activities which are likely to have air quality impacts;

(ii) Monitoring at the air sensitive receivers as defined in the EIAO-TM; and

(iii) Assurance of minimal disturbance to the occupants during monitoring.

4.21 When positioning the HVSs, the following points should be noted:

(i) A horizontal platform with appropriate support to secure the samplers against gusty wind should be provided;

(ii) no two samplers should be placed less than 2m apart;

(iii) the distance between the sampler and an obstacle, such as buildings, must be at least twice the height that the obstacle protrudes above the sampler;

(iv) a minimum of 2m separation from walls, parapets and penthouses is required for rooftops samplers;

(v) a minimum of 2m separation from any supporting structure, measures horizontally is required;

(vi) no furnace or incinerator flue is nearby;

(vii) airflow around the sampler is unrestricted;

(viii) the sampler is more than 20m from the dripline;

(ix) any wire fence and gate to protect the sampler, should not cause any obstruction during monitoring;

(x) permission must be obtained to set up the samplers and to obtain access to the monitoring stations; and

(xi) a secured supply of electricity is needed to operate the samplers.

Baseline Monitoring

4.22 Baseline monitoring should be carried out to determine the ambient 1-hour and 24‑hour TSP levels at the monitoring locations prior to the commencement of the Project works. Before commencing the baseline monitoring, the ET leader should inform the IEC of the baseline monitoring programme such that the IEC can conduct on-site audit to ensure accuracy of the baseline monitoring results.

4.23 During the baseline monitoring, there should not be any construction or dust generating activities in the vicinity of the monitoring stations. TSP baseline monitoring should be carried out for a continuous period of at least two weeks with the 24-hour and three sets of 1-hour ambient measurements taken daily at each monitoring location. General meteorological conditions (wind speed, direction and precipitation) and notes regarding any significant adjacent dust producing sources should also be recorded throughout the baseline monitoring period. A summary of baseline monitoring is presented in Table 4.2.

4.24 The baseline monitoring will provide data for the determination of the appropriate Action levels with the Limit levels set against statutory or otherwise agreed limits. In case the baseline monitoring cannot be carried out at the designated monitoring locations during the baseline monitoring period, the ET leader should carry out the monitoring at alternative locations that can effectively represent the baseline conditions at the impact monitoring locations.

4.25 In exceptional cases, when insufficient baseline monitoring data or questionable results are obtained, the ET should liaise with IEC and EPD to agree on an appropriate set of data to be used as a baseline reference and submit to ER for approval.

4.26 Ambient conditions may vary seasonally and should be reviewed once every three months. When the ambient conditions have changed and a repeat of the baseline monitoring is required to be carried out for obtaining the updated baseline levels, the monitoring should be at times when the Contractor's activities are not generating dust, at least in the proximity of the monitoring stations. Should change in ambient conditions be determined, the baseline levels and, in turn, the air quality criteria, should be revised. The revised baseline levels and air quality criteria should be agreed with the IEC and EPD.

Impact Monitoring

4.27 Before commencing baseline monitoring, the ET should inform the IEC of the impact monitoring programme such that the IEC can conduct on-site audit to ensure accuracy of the impact monitoring results.

4.28 For regular 24-hour TSP impact monitoring, a sampling frequency of at least once in every six days should be strictly observed at the monitoring stations when there are Project related construction activities being undertaken within a radius of 300m from these monitoring stations. For 1-hour TSP monitoring, the sampling frequency of at least three times in every six-days should be undertaken when the highest dust impact occurs.

4.29 In case of non-compliance with the air quality criteria, more frequent monitoring, as specified in the Action Plan in the following section, should be conducted within 24 hours after the result is obtained. This additional monitoring should be continued until the excessive dust emission or the deterioration in the air quality is rectified.

4.30 A summary of the impact monitoring programme is presented in Table 4.2.

Table 4.2 Summary of Dust Monitoring Programme

Monitoring Period	Duration	Sampling Parameter	Frequency
Baseline Monitoring	Consecutive days of at least 2 weeks before commencement of construction works	1 hour TSP	· 3 times per day
Baseline Monitoring		Continuous 24-hour TSP	· Daily
Impact Monitoring	Throughout the construction phase*	1 hour TSP	· 3 times in every 6 days
Impact Monitoring	Throughout the construction phase*	Continuous 24-hour TSP	· Once every 6 days

Noted: * Impact monitoring should be conducted at the monitoring stations for 24-hour TSP monitoring when there are Project related construction activities being undertaken within a radius of 300m from these monitoring stations.

Compliance Assessment

4.31 Action and Limit (A/L) levels that provide an appropriate framework for the interpretation of monitoring results have to be agreed between ET, IEC, EPD and the ER before commencement of the air monitoring. The air quality monitoring data should be checked against the agreed A/L levels. Recommended A/L levels are listed in Table 4.3.

Table 4.3 Proposed Action and Limit Levels for Impact Monitoring

Parameter

Action Level ⁽¹⁾

Limit Level

24-hour TSP

· BL £ 200μg m^-3, AL = (BL * 1.3 + LL)/2

· BL > 200μg m^-3, AL = LL

260 μg m^-3

1-hour TSP

· BL £ 384μg m^-3, AL = (BL * 1.3 + LL)/2

· BL > 384μg m^-3,AL = LL

500 μg m^-3

(1) BL = Baseline level, AL = Action level, LL = Limit level.

Event and Action Plan

4.32 In the cases where exceedance of these A/L levels occurs, actions in accordance with the Event and Action Plan in Table 4.4 should be carried out.

Table 4.4 Event and Action Plan for Construction Dust Monitoring

EVENT	ACTION
ACTION LEVEL
1. Exceedance for one sample	1. Identify source, investigate the causes of complaint and propose remedial measures; 2. Inform IEC and ER; 3. Repeat measurement to confirm finding; 4. Increase monitoring frequency to daily. (The above actions should be taken within 2 working days after the exceedance is identified.)	1. Check monitoring data submitted by ET; 2. Check Contractor’s working method. (The above actions should be taken within 2 working days after the exceedance is identified.)	1. Notify Contractor. (The above actions should be taken within 2 working days after the exceedance is identified.)	1. Rectify any unacceptable practice; 2. Amend working methods if appropriate. (The above actions should be taken within 2 working days after the exceedance is identified.)
2. Exceedance for two or more consecutive samples	1. Identify source; 2. Inform IEC and ER; 3. Advise the ER on the effectiveness of the proposed remedial measures; 4. Repeat measurements to confirm findings; 5. Increase monitoring frequency to daily; 6. Discuss with IEC and Contractor on remedial actions required; 7. If exceedance continues, arrange meeting with IEC and ER; 8. If exceedance stops, cease additional monitoring. (The above actions should be taken within 2 working days after the exceedance is identified.)	1. Check monitoring data submitted by ET; 2. Check Contractor’s working method; 3. Discuss with ET and Contractor on possible remedial measures; 4. Advise the ET on the effectiveness of the proposed remedial measures; 5. Supervise Implementation of remedial measures. (The above actions should be taken within 2 working days after the exceedance is identified.)	1. Confirm receipt of notification of failure in writing; 2. Notify Contractor; 3. Ensure remedial measures properly implemented. (The above actions should be taken within 2 working days after the exceedance is identified.)	1. Submit proposals for remedial to ER within three working days of notification; 2. Implement the agreed proposals; 3. Amend proposal if appropriate. (The above actions should be taken within 2 working days after the exceedance is identified.)
LIMIT LEVEL
1. Exceedance for one sample	1. Identify source, investigate the causes of exceedance and propose remedial measures; 2. Inform IEC, ER, Contractor and EPD; 3. Repeat measurement to confirm finding; 4. Increase monitoring frequency to daily; 5. Assess effectiveness of Contractor’s remedial actions and keep IEC, EPD and ER informed of the results. (The above actions should be taken within 2 working days after the exceedance is identified.)	1. Check monitoring data submitted by ET; 2. Check Contractor’s working method; 3. Discuss with ET and Contractor on possible remedial measures; 4. Advise the ER on the effectiveness of the proposed remedial measures; 5. Supervise implementation of remedial measures. (The above actions should be taken within 2 working days after the exceedance is identified.)	1. Confirm receipt of notification of failure in writing; 2. Notify Contractor; 3. Ensure remedial measures properly implemented. (The above actions should be taken within 2 working days after the exceedance is identified.)	1. Take immediate action to avoid further exceedance; 2. Submit proposals for remedial actions to IEC within three working days of notification; 3. Implement the agreed proposals; 4. Amend proposal if appropriate. (The above actions should be taken within 2 working days after the exceedance is identified.)
2. Exceedance for two or more consecutive samples	1. Notify IEC, ER, Contractor and EPD; 2. Identify source; 3. Repeat measurement to confirm findings; 4. Increase monitoring frequency to daily; 5. Carry out analysis of Contractor’s working procedures to determine possible mitigation to be implemented; 6. Arrange meeting with IEC and ER to discuss the remedial actions to be taken; 7. Assess effectiveness of Contractor’s remedial actions and keep IEC, EPD and ER informed of the results; 8. If exceedance stops, cease additional monitoring. (The above actions should be taken within 2 working days after the exceedance is identified.)	1. Discuss amongst ER, ET, and Contractor on the potential remedial actions; 2. Review Contractor’s remedial actions whenever necessary to assure their effectiveness and advise the ER accordingly; 3. Supervise the implementation of remedial measures. (The above actions should be taken within 2 working days after the exceedance is identified.)	1. Confirm receipt of notification of failue in writing; 2. Notify Contractor; 3. In consultation with the IEC, agree with the Contractor on the remedial measures to be implemented; 4. Ensure remedial measures properly implemented; 5. If exceedance continues, consider what portion of the work is responsible and instruct the Contractor to stop that portion of work until the exceedance is abated. (The above actions should be taken within 2 working days after the exceedance is identified.)	1. Take immediate action to avoid further exceedance; 2. Submit proposals for remedial actions to IEC within three working days of notification; 3. Implement the agreed proposals; 4. Resubmit proposals if problem still not under control; 5. Stop the relevant portion of works as determined by the ER until the exceedance is abated. (The above actions should be taken within 2 working days after the exceedance is identified.)

EVENT

ACTION

IEC

CONTRACTOR

ACTION LEVEL

1. Exceedance for one sample

1. Identify source, investigate the causes of complaint and propose remedial measures;

2. Inform IEC and ER;

3. Repeat measurement to confirm finding;

4. Increase monitoring frequency to daily.

(The above actions should be taken within 2 working days after the exceedance is identified.)

1. Check monitoring data submitted by ET;

2. Check Contractor’s working method.

(The above actions should be taken within 2 working days after the exceedance is identified.)

1. Notify Contractor.

(The above actions should be taken within 2 working days after the exceedance is identified.)

1. Rectify any unacceptable practice;

2. Amend working methods if appropriate.

(The above actions should be taken within 2 working days after the exceedance is identified.)

2. Exceedance for two or more consecutive samples

1. Identify source;

2. Inform IEC and ER;

3. Advise the ER on the effectiveness of the proposed remedial measures;

4. Repeat measurements to confirm findings;

5. Increase monitoring frequency to daily;

6. Discuss with IEC and Contractor on remedial actions required;

7. If exceedance continues, arrange meeting with IEC and ER;

8. If exceedance stops, cease additional monitoring.

(The above actions should be taken within 2 working days after the exceedance is identified.)

1. Check monitoring data submitted by ET;

2. Check Contractor’s working method;

3. Discuss with ET and Contractor on possible remedial measures;

4. Advise the ET on the effectiveness of the proposed remedial measures;

5. Supervise Implementation of remedial measures.

(The above actions should be taken within 2 working days after the exceedance is identified.)

1. Confirm receipt of notification of failure in writing;

2. Notify Contractor;

3. Ensure remedial measures properly implemented.

(The above actions should be taken within 2 working days after the exceedance is identified.)

1. Submit proposals for remedial to ER within three working days of notification;

2. Implement the agreed proposals;

3. Amend proposal if appropriate.

(The above actions should be taken within 2 working days after the exceedance is identified.)

LIMIT LEVEL

1. Exceedance for one sample

1. Identify source, investigate the causes of exceedance and propose remedial measures;

2. Inform IEC, ER, Contractor and EPD;

3. Repeat measurement to confirm finding;

4. Increase monitoring frequency to daily;

5. Assess effectiveness of Contractor’s remedial actions and keep IEC, EPD and ER informed of the results.

(The above actions should be taken within 2 working days after the exceedance is identified.)

1. Check monitoring data submitted by ET;

2. Check Contractor’s working method;

3. Discuss with ET and Contractor on possible remedial measures;

4. Advise the ER on the effectiveness of the proposed remedial measures;

5. Supervise implementation of remedial measures.

(The above actions should be taken within 2 working days after the exceedance is identified.)

1. Confirm receipt of notification of failure in writing;

2. Notify Contractor;

3. Ensure remedial measures properly implemented.

(The above actions should be taken within 2 working days after the exceedance is identified.)

1. Take immediate action to avoid further exceedance;

2. Submit proposals for remedial actions to IEC within three working days of notification;

3. Implement the agreed proposals;

4. Amend proposal if appropriate.

(The above actions should be taken within 2 working days after the exceedance is identified.)

2. Exceedance for two or more consecutive samples

1. Notify IEC, ER, Contractor and EPD;

2. Identify source;

3. Repeat measurement to confirm findings;

4. Increase monitoring frequency to daily;

5. Carry out analysis of Contractor’s working procedures to determine possible mitigation to be implemented;

6. Arrange meeting with IEC and ER to discuss the remedial actions to be taken;

7. Assess effectiveness of Contractor’s remedial actions and keep IEC, EPD and ER informed of the results;

8. If exceedance stops, cease additional monitoring.

(The above actions should be taken within 2 working days after the exceedance is identified.)

1. Discuss amongst ER, ET, and Contractor on the potential remedial actions;

2. Review Contractor’s remedial actions whenever necessary to assure their effectiveness and advise the ER accordingly;

3. Supervise the implementation of remedial measures.

(The above actions should be taken within 2 working days after the exceedance is identified.)

1. Confirm receipt of notification of failue in writing;

2. Notify Contractor;

3. In consultation with the IEC, agree with the Contractor on the remedial measures to be implemented;

4. Ensure remedial measures properly implemented;

5. If exceedance continues, consider what portion of the work is responsible and instruct the Contractor to stop that portion of work until the exceedance is abated.

(The above actions should be taken within 2 working days after the exceedance is identified.)

1. Take immediate action to avoid further exceedance;

2. Submit proposals for remedial actions to IEC within three working days of notification;

3. Implement the agreed proposals;

4. Resubmit proposals if problem still not under control;

5. Stop the relevant portion of works as determined by the ER until the exceedance is abated.

(The above actions should be taken within 2 working days after the exceedance is identified.)

Mitigation Measures

4.33 Dust mitigation measures stipulated in the Air Pollution Control (Construction Dust) Regulation should be implemented to control dust emissions from all construction work sites.

Ÿ Use of regular watering, with complete coverage, to reduce dust emissions from exposed site surfaces and unpaved roads, particularly during dry weather.

Ÿ Use of frequent watering for particularly dusty construction areas and areas close to ASRs.

Ÿ Side enclosure and covering of any aggregate or dusty material storage piles to reduce emissions. Where this is not practicable owing to frequent usage, watering shall be applied to aggregate fines.

Ÿ Open stockpiles shall be avoided or covered. Where possible, prevent placing dusty material storage piles near ASRs.

Ÿ Tarpaulin covering of all dusty vehicle loads transported to, from and between site locations.

Ÿ Establishment and use of vehicle wheel and body washing facilities at the exit points of the site.

Ÿ Provision of wind shield and dust extraction units or similar dust mitigation measures at the loading points, and use of water sprinklers at the loading area where dust generation is likely during the loading process of loose material, particularly in dry seasons/ periods.

Ÿ Provision of not less than 2.4m high hoarding from ground level along site boundary where adjoins a road, streets or other accessible to the public except for a site entrance or exit.

Ÿ Imposition of speed controls for vehicles on site haul roads.

Ÿ Where possible, routing of vehicles and positioning of construction plant should be at the maximum possible distance from ASRs.

Ÿ Every stock of more than 20 bags of cement or dry pulverised fuel ash (PFA) should be covered entirely by impervious sheeting or placed in an area sheltered on the top and the 3 sides.

Ÿ Instigation of an environmental monitoring and auditing program to monitor the construction process in order to enforce controls and modify method of work if dusty conditions arise.

4.34 Other site-specific mitigation measures are presented in Appendix A.