2                    AIR QUALITY

2.1              Introduction

2.1.1        In this section, the requirements, methodology, equipment, monitoring locations, criteria and protocols for the monitoring and audit of air quality impacts during the construction phase of the CWB & IECL are presented.  As construction dust is the prime concern, levels of Total Suspended Particulates (TSP) shall be monitored to evaluate the dust impact during the construction phase.

2.2              Air Quality Parameters

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

2.2.2        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 ER, 1-hour TSP levels can be measured by direct reading methods which are capable of producing comparable results as that measured by the high volume sampling method, to indicate short event impacts.

2.2.3        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 B1.

2.2.4        The locations of air sensitive receivers are shown in Figure 2.1.

2.3              Monitoring Equipment

2.3.1        High volume samplers (HVSs) in compliance 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 changable the filter; and

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

2.3.2        The ET is responsible for provision of the monitoring equipment.  They shall ensure that sufficient number of HVSs with an appropriate calibration kit are 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.

2.3.3        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 concerned parties such as ER shall properly document the calibration data for future reference.  All the data should be converted into standard temperature and pressure condition.

2.3.4        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 B1.

2.3.5        If the ET proposes to use a direct reading dust meter to measure 1-hour TSP levels, he shall submit sufficient information to the ER 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.

2.3.6        Wind data monitoring equipment shall also be provided and 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 ER.  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 shall be re-calibrated at least once every six months.

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

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

2.4              Laboratory Measurement / Analysis

2.4.1        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.

2.4.2        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 ER.  Any measurement performed by the laboratory shall be demonstrated to the satisfaction of the IE(C) who 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.

2.4.3        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 sampling.

2.4.4        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.

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

2.5              Monitoring Locations

2.5.1        Based on the EIA report, five worst affected locations are designated for construction dust monitoring as listed in Table 2.1 and illustrated in Figure 2.1.  The status and locations of dust 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 IC(E) and agreement from EPD on the proposal.

Table 2.1         Construction Dust Monitoring Locations

Identification No.

Location

MA1

Central – Airport Railway Hong Kong Station

MA2

Wanchai – Pedestrian Plaza

MA3

Wanchai – Wanchai Sports Ground

MA4

Causeway Bay – Bowling Green, Victoria Park

MA5

Causeway Bay – Royal Hong Kong Yacht Club

2.5.2        When alternative monitoring locations are proposed, the monitoring 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.

2.5.3        The ET shall agree with the ER 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 of 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.

2.6              Baseline Monitoring

2.6.1        Baseline monitoring shall be carried out at all of the designated monitoring locations for at least 14 consecutive days prior to the commissioning of the 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. 

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

2.6.3        In case the baseline monitoring cannot be carried out at the designated monitoring locations during the baseline monitoring period, the ET Leader shall carry out the monitoring at alternative locations which can effectively represent the baseline conditions at the impact monitoring locations.  The alternative baseline monitoring locations shall be approved by the ER and IC(E) and agreed with EPD.

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

2.6.5        Ambient conditions may vary seasonally and shall be reviewed once every three months.  When the ambient conditions have changed, 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 shall be agreed with EPD.

2.7              Impact Monitoring of Construction Air Quality Impact

2.7.1        The ET shall carry out impact monitoring during the course of the Works.  For regular impact monitoring, the sampling frequency of at least once in every six-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 three times in every six-days should be undertaken when the highest dust impact occurs.  Before commencing baseline monitoring, the ET shall inform the ER of the impact monitoring programme.

2.7.2        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 operator.

2.7.3        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 24 hours after the result is obtained.  This additional monitoring shall be continued until the excessive dust emission or the deterioration in air quality is rectified.

2.8              Environmental Quality Performance Limits

2.8.1        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 2.2 shows the air quality criteria, namely Action and Limit levels to be used.

Table 2.2         Action / Limit Levels for Air Quality

 

Parameters

 

Action

 

Limit

 

24-hour TSP Level in mg m-3

 

For baseline level £ 200 mg m-3, Action level = (baseline level * 1.3 + Limit level)/2;

For baseline level > 200 mg m-3 Action level = Limit level

 

260

 

1-hour TSP Level in mg m-3

 

For baseline level £ 384 mg m-3, Action level = (baseline level * 1.3 + Limit level)/2;

For baseline level > 384 mg m-3, Action level = Limit level

 

500

2.9              Event and Action Plan for Construction Air Quality

2.9.1        Should non-compliance of the air quality criteria occur, actions in accordance with the Action Plan in Table 2.3 shall be carried out.

 

Table 2.3         Event / Action Plan for Air Quality

EVENT

ACTION

ET

IC(E)

ER

CONTRACTOR

 

ACTION LEVEL

 

1.      Exceedance for one sample

 

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

2.      Inform IC(E) and ER;

3.      Repeat measurement to confirm finding;

4.      Increase monitoring frequency to daily.

 

1.      Check monitoring data submitted by ET;

2.      Check Contractor’s working method.

 

1.      Notify Contractor.

 

1.      Rectify any unacceptable practice;

2.      Amend working methods if appropriate.

 

2.      Exceedance for two or more consecutive samples

1.         Identify source;

2.      Inform IC(E) 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 IC(E) and Contractor on remedial actions required;

7.      If exceedance continues, arrange meeting with IC(E) and ER;

8.      If exceedance stops, cease additional monitoring;

 

1.      Checking 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.

 

1.      Confirm receipt of notification of failure in writing;

2.      Notify Contractor;

3.       Ensure remedial measures properly implemented.

 

 

1.      Submit proposals for remedial to ER within 3 working days of notification;

2.      Implement the agreed proposals;

3.      Amend proposal if appropriate.

 

LIMIT LEVEL

 

1.      Exceedance for one sample

 

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

2.      Inform 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 IC(E), EPD and ER informed of the results.

 

1.      Checking 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.

 

1.      Confirm receipt of notification of failure in writing;

2.      Notify Contractor;

3.      Ensure remedial measures properly implemented.

 

1.        Take immediate action to avoid further exceedance;

2.        Submit proposals for remedial actions to IC(E) within 3 working days of notification;

3.        Implement the agreed proposals;

4.        Amend proposal if appropriate.

 

2.      Exceedance for two or more consecutive samples

 

1.     Notify IC(E), 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 IC(E) and ER to discuss the remedial actions to be taken;

7.     Assess effectiveness of Contractor’s remedial actions and keep IC(E), EPD and ER informed of the results;

8.     If exceedance stops, cease additional monitoring.

 

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.

 

1.       Confirm receipt of notification of failure in writing;

2.       Notify Contractor;

3.       In consolidation with the IC(E), 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.

 

1.      Take immediate action to avoid further exceedance;

2.      Submit proposals for remedial actions to IC(E) within 3 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.

2.10          Construction Dust Mitigation Measures

2.10.1    As described in the EIA Report, exceedances would occur at the air sensitive receivers from Sheung Wan to Causeway Bay during construction.  In order to achieve the air quality objective, the following mitigation measures are recommended:

CWB & IECL project (excluding works entrusted to TDD), managed by HyD

Ÿ           strictly limit the truck speed on site to below 10 km per hour and use water spraying to keep the haul roads in wet condition;

Ÿ           twice daily watering of the work site with active operations when the weather and the work site are dry;

Ÿ           watering during excavation and material handling;

Ÿ           provision of vehicle wheel and body washing facilities at the exit points of the site, combined with cleaning of public roads where necessary; and

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

CWB entrusted works, managed by TDD under WDII project

Ÿ           strictly limit the truck speed on site to below 10 km per hour and use water spraying to keep the haul roads in wet condition;

Ÿ           twice daily watering of the work site with active operations when the weather and the work site are dry;

Ÿ           watering during excavation and material handling;

Ÿ           provision of vehicle wheel and body washing facilities at the exit points of the site, combined with cleaning of public roads where necessary; and

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

CWB entrusted works, managed by TDD under CRIII project

Ÿ         strictly limit the truck speed on site to below 10 km per hour and use water spraying to keep the haul roads in wet condition;

Ÿ         twice daily watering of the work site with active operations when the weather and the work site are dry;

Ÿ         watering during excavation and material handling;

Ÿ         provision of vehicle wheel and body washing facilities at the exit points of the site, combined with cleaning of public roads where necessary; and

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

2.10.2    In addition, good site practices shall be implemented to minimise the cumulative dust impacts and the requirements of the Air Pollution Control (Construction Dust) Regulation shall be adhered to.

2.10.3    If the above measures are not sufficient to restore the air quality to acceptable levels upon the advice of ET Leader, the Contractor shall liaise with the ET Leader on some other mitigation measures, propose to ER for approval, and implement the mitigation measures.

2.10.4    The implementation schedule for the mitigation measures is presented in Appendix A.

2.11          Tunnel Emission

2.11.1    The tunnel air quality monitoring requirements for the control of air pollution in vehicle tunnels are presented in the following:

Air Quality Parameters and Standards

2.11.2    Table 1.2 shows the air quality guidelines that should be attained and maintained inside a vehicle tunnel.  In addition, the visibility in the tunnel should be controlled to a level equivalent to an extinction coefficient of 0.005 per metre or less during any 5-minute interval.

Monitoring Requirement

2.11.3    Concentrations of carbon monoxide, nitrogen dioxide and visibility should be continuously monitored inside the underpass (tunnel section of the CWB & IECL).  The tunnel management should install and operate at least one analyser for each pollutant at each kilometre section of the tunnel.

2.11.4    The monitoring of nitrogen dioxide may be replaced by nitric oxide through the application of the following equation or any correlation relationship between these two parameters demonstrated to have a regression coefficient of not less than 0.85:

Nitrogen dioxide concentration (mg m-3) = 320 + 0.1056 x Nitric oxide concentration

   (mg m-3)

2.11.5    Direct measurement of NO2 should be conducted when more suitable NO2 sensors become available in market.  In case NO2 sensors are installed, they would have to be replaced over reasonable period of time when more suitable NO2 sensors become available in market.

2.11.6    Tunnel management should forward the results of monitoring once per month on a floppy disk in such a format agreeable to the EPD.

2.11.7    All monitoring instruments should be checked for zero and span once a week and calibrated and certified by an independent environmental laboratory in accordance with the criteria.

2.11.8    The analysers should activate an audible alarm at the main control room of the tunnel whenever the measured carbon monoxide and nitrogen dioxide concentrations exceed 60,000 mg m-3 and 1,000 mg m-3, respectively.  Table 2.4 shows the Action and Limit Levels recommended for tunnel air quality.  Prompt action including restriction of the traffic flow and other means acceptable to the EPD should be taken by the tunnel operator based on a suitable action level agreed with EPD or other regulatory authority.