2 AIR QUALITY

2.1.1 Dust impacts would be the major air quality impacts during the construction phase of the project. It is necessary to monitor the dust generates from the construction activities after timely implementation of the mitigation measures listed in Sections 2.9 and 2.10 respectively in this Manual. The purpose of monitoring is to ascertain that the dust levels would comply with the 1-hour average and 24-hour average Total Suspended Particulate (TSP) criteria at the sensitive receivers, and that the recommended mitigation measures are effective in suppressing dust levels.

2.1.2 The objectives of the monitoring are:

(a) to identify the extent of construction dust impacts on nearby sensitive receivers;

(b) to determine the effectiveness of the recommended dust mitigation measures to control dust from construction activities;

(d) to ascertain that the dust levels would comply with the 1-hour average and 24-hour average Total Suspended Particulates (TSP) criteria at nearby sensitive receivers as defined in this EM&A Manual.

2.2 Air Quality Parameters

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

2.2.2 1-hour and 24-hour TSP levels shall be measured to indicate the impacts of construction dust on air quality. The 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 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 and work progress of the concerned site etc. shall be recorded down in details. A sample data record sheet is shown in Appendix B for reference.

2.3 Monitoring Equipment

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

(a) 0.6-1.7m3/min (20-60 SCFM) adjustable flow range;

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

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

(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) easy to change the filter; and

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

2.3.2 The ET Leader shall be responsible for provision of the monitoring equipment. He/she 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 by the ET 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 calibration data shall be properly documented for future reference by the concerned parties such as the IEC. All the data shall 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 down in the data sheet (see Appendix B).

2.3.5 If the ET Leader proposes to use a direct reading dust meter to measure 1-hour TSP levels, he/she shall submit sufficient information to the IEC to prove that the instrument is capable of achieving a comparable result as that of the HVS and may be used for the 1-hour sampling. The instrument shall also be calibrated regularly, and the 1-hour sampling shall be determined periodically by 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 at conspicuous locations for logging wind speed and wind direction near to the dust monitoring locations. The equipment installation location shall be proposed by the ET Leader and agreed with the ER in consultation with the IEC. For installation and operation of wind data monitoring equipment, the following points shall be observed:

(a) the wind sensors shall be installed on masts at an elevated level 10m above ground so that they are clear of obstructions or turbulence caused by the buildings;

(b) the wind data shall be captured by a data logger. The data recorded in the data logger shall be downloaded periodically for analysis at least once a month;

(d) wind direction shall be divided into 16 sectors of 22.5 degrees each.

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

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 shall be HOKLAS accredited or other internationally accredited laboratory.

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 in consultation with the IEC. Measurement performed by the laboratory shall be demonstrated to the satisfaction of the ER and the IEC.

2.4.3 The IEC shall conduct regular audit to the measurement performed by the laboratory so as 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/her reference.

2.4.4 Filter paper of size 8"x10" shall be labelled before sampling. It shall be a clean filter paper with no pin holes, and shall be conditioned in a humidity controlled chamber for over 24-hour and be pre-weighed before use for the sampling.

2.4.5 After sampling, the filter paper loaded with dust shall be kept in a clean and tightly sealed plastic bag. The filter paper is then returned to the laboratory for reconditioning in the humidity-controlled chamber followed by accurate weighing by an electronic balance with a readout down to 0.1mg. The balance shall be regularly calibrated against a traceable standard.
2.4.6 All the collected samples shall be kept in a good condition for 6 months before disposal.

2.5 Monitoring Locations

2.5.1 Impact monitoring of dust shall be carried out at representative ASRs whenever there is ongoing construction work during construction phase of DBL. Five dust monitoring stations near the following air sensitive receivers are proposed to set up in the vicinity of the works areas and Lam Tei Interchange in Table 2.1:

Table 2.1 Proposed Dust Monitoring Stations for Construction Phase EM&A

Work Section	Noise Sensitive Receiver	Monitoring Station	Description
Ngau Hom Shek	E24	AN1 (8110)	Village house at Ngau Hom Shek
Ngau Hom Shek	E24	A8 (8116)	Village house at Ngau Hom Shek
Between HSK Exit and Lam Tei Interchange	E14	AN3 (8329)	Tsing Chuen Wai
Lam Tei Interchange	E13	AN6 (8329)	Tsoi Yuen Tsuen
Lam Tei Interchange	E4	AN7 (8801)	Lam Tei Gospel School

Note:

For locations of dust monitoring location, please refer to the corresponding location of air sensitive receivers in Figure 2.1.

2.5.2 Figure 2.1 shows the locations of the proposed dust monitoring stations. 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 agreement from the IEC.

2.5.3 When alternative monitoring locations are proposed, the following criteria, as far as practicable, shall be followed:

(a) at the site boundary or such locations close to the major dust emission source;

(b) close to the air sensitive receivers;

(d) take into account the prevailing meteorological conditions.

2.5.4 The ET Leader shall agree with the ER in consultation with the IEC the position of the HVS for 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 shall be provided;

(b) no two samplers shall be placed less than 2 meter 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 metres of separation from walls, parapets and penthouses is required for rooftop samplers;

(e) a minimum of 2 metre 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 metres from the dripline;

(i) any wire fence and gate, to protect the sampler, shall 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 The ET Leader shall carry out baseline monitoring 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. 1-hour sampling shall also be done at least 3 times per day while the highest dust impact is expected. Before commencing the baseline monitoring, the ET Leader shall 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.

2.6.2 During the baseline monitoring, there shall not be any construction or dust generation activities in the vicinity of the monitoring stations.

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 agreed with IEC.
2.6.4 In exceptional case, when insufficient baseline monitoring data or questionable results are obtained, the ET Leader 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.

2.6.5 Ambient conditions may vary seasonally and shall be reviewed at three monthly intervals. If the ET leader considers that the ambient conditions have been changed and a repeat of the baseline monitoring is required to be carried out for obtaining the updated baseline levels, the monitoring shall be at times when the contractor's activities are not generating dust, at least in the proximity of the monitoring stations. Shall change in ambient conditions be determined, the baseline levels and, in turn, the air quality criteria, shall be revised. The revised baseline levels and air quality criteria shall be agreed with the IEC and EPD.

2.7 Impact Monitoring

2.7.1 The ET Leader shall carry out impact monitoring during construction phase of DBL. 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 shall be undertaken when the highest dust impact occurs. Before commencing the impact monitoring, the ET Leader shall 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.

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 field operator.

2.7.3 In case of non-compliance with the air quality criteria, more frequent monitoring exercise, as specified in the Action Plan in Section 2.8, 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 Event and Action Plan for Air Quality

2.8.1 The baseline monitoring results form the basis for determining the air quality criteria for the impact monitoring. The ET Leader 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. Should non-compliance of the air quality criteria occurs, the ET Leader, ER, and Contractor shall undertake relevant actions in accordance with the Action Plan as stated Table 2.3.

Table 2.2 Action and Limit Levels for Air Quality (Dust)

Parameters	Action	Limit
24 Hour TSP Level in µg/m3	For baseline level 200 µg/m3, Action level = (Baseline level * 1.3 + Limit level)/2 For baseline level > 200 µg/m3, Action level = Limit level	260
1 Hour TSP Level in µg/m3	For baseline level 384 µg/m3, Action level = (Baseline level * 1.3 + Limit level)/2 For baseline level > 384 µg/m3, Action level = Limit level	500

Table 2.3 Event/Action Plan for Air Quality (Dust)

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

2.9 Dust Mitigation Measures

2.9.1 The EIA Report has recommended dust control mitigation measures to minimise the impacts. The Contractor shall be responsible for the design and implementation of these measures. If the recommended mitigation measures are not sufficient to restore the air quality to acceptable levels upon the advice of ET, the Contractor shall liaise with the ET on some other mitigation measures, propose to ER for approval, and implement the mitigation measures.

2.9.2 In order to ensure that dust emission is minimised during the construction phase of the project, relevant dust control requirements set out in the Air Pollution Control (Construction Dust) Regulation shall be met. The construction contractors are required to adopt dust reduction measures when carrying out construction works.

2.9.3 Recommended dust mitigation measures to minimise dust and the effects of dust on sensitive receivers during construction of the project shall be adopted and are detailed as follows:

Construction Phase

2.9.4 In order to ensure that dust emission is minimised during the construction phase of the road works, relevant dust control requirements set out in Parts I, III and IV of Schedule 1 of the Air Pollution Control (Construction Dust) Regulation shall be met. The site agent is required to adopt dust reduction measures while carrying out construction works. In particular, the mitigation measures listed below shall be adopted where applicable. With the implementation of effective dust control measures, adverse dust impacts from the construction works of the project is not expected.

Site clearance and demolition of existing structures

The working area for the uprooting of trees, shrubs, or vegetation or for the removal of boulders, poles, pillars or temporary or permanent structures shall be sprayed with water or a dust suppression chemical immediately before, during and immediately after the operation so as to maintain the entire surface wet;
All demolished items (including trees, shrubs, vegetation, boulders, poles, pillars, structures, debris, rubbish and other items arising from site clearance) that may dislodge dust particles shall be covered entirely by impervious sheeting or placed in an area sheltered on the top and the 3 sides within a day of demolition;

Site boundary and entrance

Vehicle washing facilities including a high pressure water jet shall be provided at every discernible or designated vehicle exit point;
The area where vehicle washing takes place and the section of the road between the washing facilities and the exit point shall be paved with concrete, bituminous materials or hardcores;
Where a site boundary adjoins a road, street, service and or other area accessible to the public, hoarding of not less than 2.4m from ground level shall be provided along the entire length of that portion of the site boundary except for a site entrance or exit;

Access road

Every main haul road (i.e. any course inside a construction site having a vehicle passing rate of higher than 4 in any 30 minutes) shall be paved with concrete, bituminous materials, hardcores or metal plates, and kept clear of dusty materials; or sprayed with water or a dust suppression chemical so as to maintain the entire road surface wet;
The portion of any road leading only to a construction site that is within 30m of a discernible or designated vehicle entrance or exit shall be kept clear of dusty materials;

Use of vehicle

Immediately before leaving a construction site, every vehicle shall be washed to remove any dusty materials from its body and wheels;
Where a vehicle leaving a construction site is carrying a load of dusty materials, the load shall be covered entirely by clean impervious sheeting to ensure that the dusty materials do not leak from the vehicle;

Concrete production

The concrete batching plant shall be located away from any air sensitive receiver as far as practicable;
If the total silo capacity of the concrete batching plant exceed 50 tonnes, the project proponent is required to obtain a Specified Process licence to ensure that any potential dust emission would be properly controlled;
Cement delivered in bulk shall be stored in a closed silo fitted with an audible high level alarm which is interlocked with the material filling line such that, in the event of the silo approaching an overfilling condition, an audible alarm is triggered and the material filling stops within one minute;
Silo used for the storage of cement shall not be overfilled;
The loading, unloading, transfer, handling or storage of any cement shall be carried out in a totally enclosed system or facility, and any vent or exhaust shall be fitted with an effective fabric filter or equivalent air pollution control system or equipment;
Cement collected by fabric filters or other pollution control system or equipment shall be disposed of in a totally enclosed containers;

Excavation and earth moving

The working area of any excavation or earth moving operation shall be sprayed with water or a dusty suppression chemical immediately before, during and immediately after the operation so as the maintain the entire surface wet;
Exposed earth shall be properly treated by compaction, turfing, hydroseeding, vegetation planting or sealing with latex, vinyl, bitumen, shotcrete or other suitable surface stabilizer within 6 months after the last construction activity on the construction site or part of the construction site where the exposed earth lies;

Stockpiling of dusty materials

Any stockpile of dusty material shall be either covered entirely by impervious sheeting; placed in an area sheltered on the top and the 3 sides; or sprayed with water or a dust suppression chemical so as to maintain the entire surface wet.