4.                              AIR QUALITY

4.1                          Introduction

4.1.1.1              Potential air quality impacts arising from the construction works would mainly be related to the construction dust from excavation, materials handling, spoil removal and wind erosion, as well as operation of the temporary stockpiles and barging points.  The construction dust monitoring and site audit are recommended to confirm that the mitigation measures recommended in the EIA report are properly implemented.  During the operational phase, there would be no adverse air quality impact anticipated and, therefore, no specific EM&A requirements are recommended during the operational phase of the KTE project.  

4.2                          Monitoring Requirements

4.2.1                    Monitoring Parameters and Equipment

4.2.1.1              The levels of total suspended particulate (TSP) should be measured by following the standard method as set out in the High Volume Method for Total Suspended Particulates, Part 50 Chapter 1 Appendix B, Title 40 of the Code of Federal Regulations of the USEPA (the HVS method) or by direct reading methods which are capable of producing comparable results as that by the high volume sampling method.

4.2.1.2              Dust laden in air should be drawn through a high volume sampler (HVS) fitted with a conditioned, pre-weighed filter paper, at a controlled rate.  After sampling for 24-hours, the filter paper with the retained dust particles should be collected and returned to the laboratory for drying in a desiccator followed by weighing.  The 24-hour average TSP levels should be calculated from the ratio of the mass of particulates retained on the filter paper to the total volume of air sampled. 

4.2.1.3              All the relevant data including the temperature, pressure, weather conditions, elapsed-time meter reading for the start and stop of HVS, identification and weight of the filter paper, and other specific phenomena and works progress of the concerned works sites, etc, should be recorded in detail.  A sample data sheet is shown in Appendix 4.1 of this EM&A Manual. 

4.2.1.4              The HVS in compliance with the following specifications should be used for carrying out the 1-hour and 24-hour monitoring for TSP levels:

(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 square inch);

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

(vi)           Incorporated with an electronic mass flow rate controller or other equivalent devices;

(vii)         Equipped with a flow recorder for continuous monitoring;

(viii)        Provided with a peaked roof inlet;

(ix)           Incorporated with a manometer;

(x)            Capable of holding and sealing the filter paper to the sampler housing at horizontal position;

(xi)           Easy to change the filter; and

(xii)         Capable of operating continuously for 24-hour periods.

4.2.1.5              The ET should be responsible for providing the monitoring equipment and should ensure that sufficient HVSs with the appropriate calibration kit are available for carrying out the baseline monitoring, regular impact monitoring and ad-hoc monitoring as required.  The HVSs should be equipped with an electronic mass flow controller and be calibrated against a traceable standard at regular intervals, in accordance with the requirements in the manufacturer’s operating manual and as described below.  All the equipment, calibration kit, filter papers, etc, should be clearly labelled.

4.2.1.6              The initial calibration of the HVSs with mass flow controller should be conducted upon the installation and thereafter in every 6 months.  The calibration should be conducted using an orifice calibrator and the calibration data should be properly documented for the future reference by the IEC.  The flow rates of the sampler before and after the sampling with the filter in position should be verified to be constant and be recorded on the data sheet as shown in Appendix 4.1.

4.2.2                    Monitoring Stations

4.2.2.1              The worst affected locations in the vicinity of the construction works sites and works areas identified for the construction dust monitoring are listed in Table 4.1 and depicted in Figures 4.1-4.4. 

Table 4.1:     Construction Dust Monitoring Locations

ID No.

ASRs

Monitoring Location

CD1

ASR7a

Queen Elizabeth Hospital – Specialist Clinic

CD2

ASR14

Yee Fu Building

CD3

ASR17

Lok Ka House

CD4

ASR28

Block 1, Cherry Mansions, Whampoa Garden Site 2

CD5

ASR34

Fung Kei Millennium Primary School

CD6

ASR46

Harbourfront Horizon

* ASRs = Air Sensitive Receivers

4.2.2.2              It should be noted that there are no monitoring stations proposed for the access shafts at Gascoigne Road Rest Garden and Fat Kwong Street Playground as the assessment results do not predict any significant dust levels at the ASRs surrounding these locations.

4.2.2.3              The status and locations of the air sensitive receivers (ASRs) may change after this EM&A Manual has been issued.  In such cases, the ET should propose the updated monitoring locations and seek approval from the ER and agreement from the IEC and EPD.  If alternative monitoring locations are proposed, they should be chosen based on the following criteria:

(i)              The monitoring at the ASRs close to the major construction site activities which are likely to be subjected to construction dust impacts due to the KTE project;

(ii)             The monitoring at the ASRs as defined in the EIAO-TM; and

(iii)           The assurance of the minimal disturbance to the occupants and working under a safety condition during monitoring. 

4.2.2.4              When positioning the HVSs, the following aspects should be noted:

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

(iv)           No two HVSs should be placed less than 2m apart;

(v)            The distance between the HVSs and an obstacle, e.g. buildings, must be at least twice the height of the obstacle protruding above the HVSs;

(vi)           A minimum of 2m separation from the walls, parapets and penthouses is required for rooftops HVSs;

(vii)         A minimum of 2m separation from any supporting structures measured horizontally is required;

(viii)        No nearby furnace or incinerator flue is allowed;

(ix)           The airflow around the HVSs is unrestricted;

(x)            The HVSs are more than 20m from the dripline;

(xi)           Any wire fences and gates to protect the HVSs should not cause obstructions during the monitoring;

(xii)         The permission must be obtained to set up the HVSs and to obtain access to the monitoring stations; and

(xiii)        A secured supply of electricity is needed to operate the HVSs.

4.2.3                    Baseline Monitoring

4.2.3.1              The 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 main construction works for the KTE project.  Prior to commencing the baseline monitoring, the ETL should inform the IEC of the baseline monitoring programme such that the IEC can conduct the on-site audit to ensure the accuracy of the baseline monitoring results. 

4.2.3.2              The baseline monitoring of TSP levels 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.  During the baseline monitoring, there should not be any construction or dust generating activities in the vicinity of the monitoring stations.  The general meteorological conditions (e.g. wind speed, direction and precipitation) and notes regarding any significant adjacent dust producing sources should be recorded throughout the baseline monitoring.  A summary of the requirements for the baseline monitoring is shown in Table 4.2. 

Table 4.2:     Summary of Construction Dust Monitoring Programme

Monitoring Period

Duration

Parameter

Frequency

Baseline Monitoring

Consecutive days of at least 2 weeks before commencement of construction works

1 hour TSP

3 times per day

Continuous 24-hour TSP

Daily

Impact Monitoring

Throughout the construction phase*

1 hour TSP

3 times per 6 days (as required in case of complaints)

Continuous 24-hour TSP

Once per 6 days

* 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 500m from these monitoring stations.

4.2.3.3              The baseline monitoring will provide environmental data for the determination of the appropriate Action levels for the air quality monitoring, whilst the Limit levels will be set against the statutory or otherwise agreed limits.  If the ET considers that significant changes in the ambient conditions have arisen, a repeat of the baseline monitoring may be carried out to update the baseline levels and Action levels, upon the consultation and agreement with the ER, IEC and EPD.  

4.2.4                    Impact Monitoring

4.2.4.1              The monthly schedule of the impact construction dust monitoring programme should be drawn up by the ET one month prior to the commencement of the scheduled construction period. 

4.2.4.2              For the regular 24-hour TSP impact monitoring, a sampling frequency of at least once per 6 days should be strictly conducted at the monitoring stations when there are main project related construction activities being conducted within a radius of 500m from these monitoring stations.  In case of complaints, the 1-hour TSP monitoring should be conducted at least three times per 6 days when the highest dust impacts are likely to occur.  The impact monitoring programme is also summarised in Table 4.2.

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

4.2.5                    Compliance Assessment

4.2.5.1              The Action and Limit (A/L) levels that provide an appropriate framework for the interpretation of monitoring results have to be agreed between the ET, IEC, EPD and ER before the commencement of the construction dust monitoring, and the monitoring data should be checked against these agreed A/L levels.  The recommended A/L levels are summarised in Table 4.3.

Table 4.3:     Action and Limit (A/L) Levels for Construction Dust Impact Monitoring

Parameter

Action Level*

Limit Level

TSP (24 hour average)

BL £ 200 μgm-3, AL = (BL x 1.3 + LL)/2

BL > 200 μgm-3, AL = LL

260 μgm-3

 

TSP (1 hour average)

BL £ 384 μgm-3, AL = (BL x 1.3 + LL)/2

BL > 384 μgm-3, AL = LL

500 μgm-3

* BL = baseline level; AL = Action level; LL = Limit level

4.2.6                    Event and Action Plan

4.2.6.1              The Event and Action Plan prescribes the procedures and action associated with the outcome of the comparison of the construction dust monitoring data recorded and the agreed A/L levels.  In the cases where exceedances of these A/L levels occur, the ET, IEC, ER and Contractor should strictly observe the relevant action of the respective Event and Action Plan as listed in Table 4.4.


Table 4.4:        Event and Action Plan for Construction Dust Monitoring

EVENT

ACTION

ET(1)

IEC(1)

ER(1)

Contractor

Action Level

 

 

 

 

1.   Exceedance for one sample

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

2.   Inform IEC and ER.

3.   Repeat measurement to confirm finding;.

4.   Increase monitoring frequency.

1.   Check monitoring data submitted by the ET.

2.   Check the Contractor’s working methods.

1.   Notify the Contractor.

1.   Rectify any unacceptable practices. 

2.   Amend working methods agreed with the ER as appropriate. 

2.   Exceedance for two or more consecutive samples

1.   Identify sources.

2.   Inform the 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 the IEC, ER and Contractor on remedial action required.

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

8.   If exceedance stops, cease additional monitoring.

1.   Check monitoring data submitted by the ET.

2.   Check the Contractor’s working methods.

3.   Discuss with the ET, ER and Contractor on possible remedial measures if required.

4.   Advise the ER on the effectiveness of proposed remedial measures if required.

1.   Notify the Contractor.

2.   Ensure remedial measures properly implemented.

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

2.   Implement the agreed proposals. 

3.   Amend proposal as appropriate. 

 

 

 

 

 

 

 

 

 

 

Limit Level

 

 

 

 

 

 

1.   Exceedance for one sample

1.   Identify sources, investigate causes of exceedance and proposed remedial measures.

2.   Inform the IEC, ER, and Contractor.

3.   Repeat measurement to confirm finding.

4.   Increase monitoring frequency to daily.

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

1.   Check monitoring data submitted by the ET.

2.   Check the Contractor’s working methods.

3.   Discuss with the ET, ER and Contractor on possible remedial measures.

4.   Advise the ER and ET on the effectiveness of the proposed remedial measures.

5.   Supervise the implementation of remedial measures.

1.   Confirm receipt of the notification of exceedance in writing.

2.   Notify the Contractor.

3.   Ensure remedial measures are properly implemented.

1.   Take immediate action to avoid further exceedance. 

2.   Submit proposals for remedial action to the ER and copy to the ET and IEC within 3 working days of notification. 

3.   Implement the agreed proposals. 

4.   Amend proposal as appropriate. 

 

 

2.   Exceedance for two or more consecutive samples

1.   Notify the IEC, ER and Contractor.

2.   Identify sources.

3.   Repeat measurements to confirm findings.

4.   Increase monitoring frequency to daily.

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

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

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

8.   If exceedance stops, cease additional monitoring.

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

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

3.   Supervise the implementation of remedial measures.

1.   Confirm receipt of the notification of exceedance in writing.

2.   Notify the Contractor.

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

4.   Ensure remedial measures are properly implemented.

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

1.   Take immediate action to avoid further exceedance.

2.   Submit proposals for remedial action to the ER and copy to the IEC and ET within 3 working days of notification.

3.   Implement the agreed proposals.

4.   Resubmit proposals if problems still not under control.

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

 

 

Note (1):  ET – Environmental Team, IEC – Independent Environmental Checker, ER – Engineer’s Representative

 

 

4.3                          Mitigation Measures

4.3.1.1              The construction dust mitigation measures stipulated in the Air Pollution Control (Construction Dust) Regulation should be implemented to control dust emissions from all construction work sites.  Details of the mitigation measures recommended in the EIA report are presented in Appendix 1.1. 

·               For the unloading of spoil from trucks at barging point and crushing plant, installation of 3-sided screen with top and the provision of water sprays at the discharge point would be provided for an assumed 50% dust suppression.  This assumption is based upon USEPA AP-42 Control Techniques for Particulate Emissions form Stationary Sources Part 2 which states that watering alone would have 50% dust removal efficiency;

·               Watering every working hour for 12 hours a day on exposed soil areas on active works areas and paved haul roads to reduce dust emissions by 91.7%, which is with reference to the “Control of Open Fugitive Dust Sources” (USEPA AP-42).  The amount of water to be applied would be 1.8L/m2;

·               The dust removal efficiency of fabric baghouse/cartridge filter type dust extraction and collection system or equivalent for rock crushing activities within an enclosure is assumed to be 99%, with reference to USEPA AP-42; 

·               The use of regular watering, with complete coverage, to reduce dust emissions from the exposed site surfaces and unpaved roads, particularly during dry weather;

·               The use of the frequent watering for particularly dusty construction works sites and works areas close to ASRs;

·               The use of side enclosure and covering of aggregates and dusty material storage piles to reduce emissions.  Where this is not practicable owing to the frequent usage, watering shall be applied to the aggregate fines;

·               Open stockpiles should be avoided or covered.  Prevent placing dusty material storage piles near ASRs;

·               The tarpaulin covering of all dusty vehicle loads transported to, from and between site locations;

·               The establishment and use of vehicle wheel and body washing facilities at the exit points of construction works sites practically;

·               The 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 areas where dust generation is likely during the loading process of loose materials, particularly in dry seasons / periods;

·               The imposition of speed control for vehicles on unpaved haul road within construction sites – 8 km per hour is the recommended limit; 

·               Routing of vehicles and positioning of construction plant should be at the maximum possible distance from ASRs;

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

·               Cement and/or dry PFA delivered in bulk should be stored in a closed silo fitted with an audible high level alarm which is interlocked with the material filling line and no overfilling is allowed; and

·               The loading, unloading, transfer, handling or storage of bulk cement or dry PFA should be carried out in a totally enclosed system or facility, and any vent or exhaust should be fitted with an effective fabric filter or equivalent air pollution control system.