5.                    Air Quality

5.1                    Air Quality Parameters

5.1.1A   Monitoring and audit of the Total Suspended Particulates (TSP) levels shall 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.

5.1.2                                 One-hour and 24-hour TSP levels should be measured to indicate the impacts of construction dust on air quality. The 24-hour TSP levels shall be measured by following the standard high volume sampling method as set out in the Title 40 of the Code of Federal Regulations, Chapter 1 (Part 50), Appendix B. Upon approval of the IEC, 1-hour TSP levels can be measured by direct reading methods which are capable of producing comparable results as that by the high volume sampling method, to indicate short event impacts.

5.1.3                        All relevant data including temperature, pressure, weather conditions, elapsed- time meter reading for the start and stop of the sampler, identification and weight of the filter paper, and any other local atmospheric factors affecting or affected by site conditions, etc., shall be recorded down in detail. A sample data sheet is shown in Appendix D.

5.2                   Monitoring Equipment

5.2.1                        High volume samplers (HVSs) complying with the following specifications shall be used for carrying out the 1-hour and 24-hour TSP monitoring:

a.      0.6 - 1.7 m3 per minute adjustable flow range;

b.      equipped with a timing / control device with +/- 5 minutes accuracy for 24 hours operation;

c.      installed with elapsed-time meter with +/- 2 minutes accuracy for 24 hours operation;

d.      capable of providing a minimum exposed area of 406 cm2;

e.      flow control accuracy: +/- 2.5% deviation over 24-hour sampling period;

f.       equipped with a shelter to protect the filter and sampler;

g.      incorporated with an electronic mass flow rate controller or other equivalent devices;

h.      equipped with a flow recorder for continuous monitoring;

i.       provided with a peaked roof inlet;

j.       incorporated with a manometer;

k.      able to hold and seal the filter paper to the sampler housing at horizontal position;

l.       easily changeable filter; and

m.    capable of operating continuously for a 24-hour period.

5.2.2                        The ET is responsible for the provision, installation, operation, maintenance, dismantle of the monitoring equipment. They shall ensure that sufficient number of HVSs with an appropriate calibration kit is available for carrying out the baseline monitoring, regular impact monitoring and ad hoc monitoring. The HVSs shall be equipped with an electronic mass flow controller and be calibrated against a traceable standard at regular intervals. All the equipment, calibration kit, filter papers, etc., shall be clearly labelled.

5.2.3                        Initial calibration of dust monitoring equipment shall be conducted upon installation and thereafter at bi-monthly intervals. The transfer standard shall be traceable to the internationally recognised primary standard and be calibrated annually. The concern parties such as IEC shall properly document the calibration data for future reference. All the data should be converted into standard temperature and pressure condition.

5.2.4                        The flow-rate of the sampler before and after the sampling exercise with the filter in position shall be verified to be constant and be recorded in the data sheet as mentioned in Appendix D.

5.2.5                        If the ET proposes to use a direct reading dust meter to measure 1-hour TSP levels, he shall 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 shall be determined periodically by the HVS to check the validity and accuracy of the results measured by direct reading method.

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

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

b.      The wind data should be captured by a data logger. The data shall be downloaded for analysis at least once a month.

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

d.      Wind direction should be divided into 16 sectors of 22.5 degrees each.

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

5.3                   Laboratory Measurement / Analysis

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

5.3.2                        If a site laboratory is set up or a non-HOKLAS accredited laboratory is hired for carrying out the laboratory analysis, the laboratory equipment shall be approved by the ER and the measurement procedures shall be witnessed by the IEC. Any measurement performed by the laboratory shall be demonstrated to the satisfaction of the ER and IEC. IEC shall regularly audit to the measurement performed by the laboratory to ensure the accuracy of measurement results. The ET Leader shall 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.

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

5.3.4                        After sampling, the filter paper loaded with dust shall be kept in a clean and tightly sealed plastic bag. The filter paper shall 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 shall be regularly calibrated against a traceable standard.

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

5.4                   Monitoring Locations

5.4.1A   Figure 5.1 shows the locations of the proposed air quality monitoring station. The status and locations of air quality sensitive receivers may change after issuing this manual. If such cases exist, the ET Leader shall propose updated monitoring locations and seek approval from ER and agreement from the IEC. The air quality monitoring locations are described in Table 5.1.

5.4.2A  When alternative air quality monitoring locations are proposed, the proposed site should, as far as practicable:

a.      Be at the site boundary or such locations close to the major dust emission source;

b.      Be close to the sensitive receptors; and

c.      Take into account the prevailing meteorological conditions.

5.4.3                                 The ET shall agree with the ER in consultation with the IEC on the position of the HVS for the installation of the monitoring equipment. When positioning the samplers, the following points shall be noted:

a.      A horizontal platform with appropriate support to secure the samplers against gusty wind should be provided;

b.      No two samplers should be placed less than 2 meters apart;

c.      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;

d.      A minimum of 2 meters separation from walls, parapets and penthouses is required for rooftop samplers;

e.      A minimum of 2 meters separation from any supporting structure, measured horizontally is required;

f.       No furnace or incinerator flue is nearby;

g.      Airflow around the sampler is unrestricted;

h.      The sampler is more than 20 meters from the dripline;

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

j.       Permission must be obtained to set up the samplers and to obtain access to the monitoring stations; and

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

 

5.4.4                        The ENPO may, depending on site conditions and monitoring results, decide whether additional monitoring locations shall be included or any monitoring locations could be removed / relocated during any stage of the construction phase.

5.5                   Baseline Monitoring for Fugitive Dust

5.5.1                        Baseline monitoring shall be carried out at all of the designated monitoring locations (see Table 5.1) for at least 14 consecutive days prior to the commissioning of major construction works to obtain daily 24-hour TSP samples. The selected baseline monitoring stations should reflect baseline conditions at the impact stations. One-hour sampling should also be done at least 3 times per day while the highest dust impact is expected.

5.5.2                        During the baseline monitoring, there should not be any major construction or dust generation activities in the vicinity of the monitoring stations. Before commencing baseline monitoring, the ET shall inform the IEC of the baseline monitoring programme such that, if required, the ER can conduct on-site audit to ensure accuracy of the baseline monitoring results.

5.5.3                        In case the baseline monitoring cannot be carried out at the designated monitoring locations, the ET Leader shall carry out the monitoring at alternative locations that can effectively represent the baseline conditions at the impact monitoring locations. The alternative baseline monitoring locations shall be approved by the ER and agreed with the IEC.

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

5.5.5                        Ambient conditions may vary seasonally and shall 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.

5.5.6A  The baseline monitoring was undertaken for the Project between September and November 2011 under Agreement CE No.35/2011 (EP) ¡§Baseline Environmental Monitoring for Hong Kong¡VZhuhai-Macao Bridge Hong Kong Projects ¡V Investigation¡¨ prior to commencement of construction of the Project. The baseline monitoring results obtained under Agreement CE No.35/2011 (EP) will be adopted for this Contract.

5.6                   Impact Monitoring for Fugitive Dust

5.6.1                        The ET shall carry out impact monitoring during the entire construction period.  For regular impact monitoring, the sampling frequency of at least once in every 6 days, shall be strictly observed at all the monitoring stations for 24-hour TSP monitoring. For 1-hour TSP monitoring, the sampling frequency of at least 3 times in every 6 days should be undertaken when the highest dust impact occurs. Before commencing impact monitoring, the ET shall inform the IEC of the impact monitoring programme such that the IEC can conduct on-site audit to ensure accuracy of the monitoring results.

5.6.2                        The specific time to start and stop the 24-hour TSP monitoring shall be clearly defined for each location and be strictly followed by the ET.

5.6.3                        In case of non-compliance with the air quality criteria, more frequent monitoring, as specified in the Action Plan in the following section, shall be conducted within the specified timeframe after the result is obtained. This additional monitoring shall be continued until the excessive dust emission or the deterioration in air quality is rectified, and agreed with the ER and the IEC.

5.7                   Action / Limit Levels

5.7.1A   The baseline monitoring results form the basis for determining the air quality criteria for the impact monitoring. The ET shall compare the impact monitoring results with air quality criteria set up for 24-hour TSP and 1-hour TSP. Table 5.2 shows the air quality criteria, namely Action and Limit levels to be used.

5.8                   Event and Action Plan

5.8.1                        Should non-compliance of the air quality criteria occur, actions in accordance with the Action Plan in Table 5.3 shall be carried out.

5.9                   Mitigation Measures

5.9.1A    The approved EIA Report has recommended dust control measures including 8 times of watering per day. During the operation of the barging facilities, good site practices such as road surface paving, dust enclosures, wheels wash facilities would be implemented to reduce the generation of dust.

5.9.2                                 All the proposed mitigation measures are summarised in the Environmental Mitigation Implementation Schedule (EMIS) in Appendix B.

5.10A      Reporting of Monitoring Data to ENPO

5.10.1A The Assignment, which involves multiple construction contracts, would be constructed concurrently with other major infrastructures such as the HKLR and TMCLKL. These interface projects will be overviewed by the ENPO. The ENPO will also oversee and coordinate the cumulative environmental issues arising from the concurrent projects.

5.10.2A  To facilitate the ENPO to evaluate environmental impacts and investigate complaints, the ET Leaders shall provide the impact air quality monitoring results within one week after the monitoring event. If the 1-hour TSP is measured by direct reading, the results shall be submitted to ENPO in the next working day. The ET Leader shall follow ENPO's requirements on the data submission format and procedures as per the current ET's practice and enable rapid response by all concerned parties.