2                     air quality

Introduction

2.1               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 all construction works are presented.  As the construction dust is the prime concern, total suspended particulates (TSP) levels shall be monitored to evaluate the dust impact during the construction phase.

 

2.2               The findings of the EIA also indicated that the existing odour sources at PTWs & SCISTW would have potential odour impact on the selected air sensitive receiver (ASR) during operational phase of the Project.  Odour monitoring would be required to determine the effectiveness of mitigation measures and monitor the odour impact on the selected ASRs.

Air Quality Parameters

Construction Phase

 

2.3               Monitoring and audit of the 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.

 

2.4               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 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.

 

2.5               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.

 

2.6               The locations of ASRs within and adjacent to the Project work site are shown in Figure 2.1 (a to i).

 

Operational Phase

 

2.7               Odour patrol should be conducted by independent trained personnel / competent persons patrolling and sniffing at the identified ASRs to indicate the operational odour impacts.  Besides, odour measurements should be conducted at the exhaust stacks of the deodorization system at SCISTW.

Monitoring Equipment

Construction Phase

 

2.8               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 changeable filter; and

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

2.9               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.

 

2.10            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.

 

2.11            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.

 

2.12            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.

 

2.13            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 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.

2.14            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

Construction Phase

 

2.15            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.

 

2.16            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.

 

2.17            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.

 

2.18            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.

 

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

Monitoring Locations

Construction Phase

 

2.20            Based on the EIA report, a number of worst affected locations are designated for construction dust monitoring as listed in Table 2.1 and illustrated in Figure 2.2 (a to g).  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.

Table 2.1          Construction Dust Monitoring Locations

ASR ID in EIA Report

Monitoring ID

Location

NP5

CM_NP1

K. Wah Centre

NP6

CM_NP2

Hong Kong & Islands Regional Office, WSD

NP7

CM_NP3

Tin Shui Street Children’s Playground

WC3

CM_WC1

Society for the Prevention of Cruelty to Animals

C1

CM_C1

Sheung Wan Fire Station

FM2

CM_FM1

Western Wholesale Food Market

CB1

CM_CB1

Cyber Centre

CB2

CM_CB2

Le Meridien Cyberport

WF2

CM_WF1

Wah Ming House, Wah Fu Estate

AB4

CM_AB1

Dairy Farm Ice and Cold Storage

SCI1

CM_SCI1

Government Dockyard Offices

SCI3

CM_SCI2

COSCO Hit Terminal

SCI6

CM_SCI3

Club House

SCI7

CM_SCI4

Works site boundary (near Ngong Shuen Chau Barracks Group 2)

2.21            When alternative 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.

2.22            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 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.

 

Operational Phase

 

2.23            A number of existing ASR and one planned ASR (namely SCI5) are identified for odour monitoring as shown in Table 2.2 and illustrated in Figure 2.3 (a to i).  The odour monitoring shall be conducted at a height of 1.5m from the ground surface.  In addition to the odour monitoring locations listed in Table 2.2, odour patrol shall also be conducted at the site boundary of each PTW and the SCISTW.

Table 2.2          Operation Odour Monitoring Locations

ASR ID in EIA Report

Monitoring ID

Location

NP3

OM_NP1

King’s Road Playground & Skating Area

NP4

OM_NP2

Customs HQ Tower (planned)

NP5

OM_NP3

K. Wah Centre

WC3

OM_WC1

Society for the Prevention of Cruelty to Animals

WC4

OM_WC2

Rest Garden near Wan Chai Interchange

C1

OM_C1

Sheung Wan Fire Station

C2

OM_C2

Water Front Divisional Police Station

C3

OM_C3

Sheung Wan Gala Point

FM2

OM_FM1

Western Wholesale Food Market

SB1

OM_SB1

University of Hong Kong Stanley Ho Sports Centre Pitch

SB2

OM_SB2

Home for the Elderly

SB3

OM_SB3

Maclehose Medical Rehabilitation Centre

SB4

OM_SB4

The Duchess of Kent Children’s Hospital

CB1

OM_CB1

Cyber Centre

CB2

OM_CB2

Le Meridien Cyberport

WF2

OM_WF1

Wah Ming House, Wah Fu Estate

AB4

OM_AB1

Dairy Farm Ice and Cold Storage

ALC3

OM_ALC1

Shell Ap Lei Chau Depot

SCI1

OM_SCI1

Government Dockyard Offices

SCI3

OM_SCI2

COSCO Hit Terminal

SCI4

OM_SCI3

KMB Depot Office

SCI5

OM_SCI4

Planned FSD Diving Rescue and Diving Training Centre

SCI6

OM_SCI5

Club House

 

Baseline Monitoring

Construction Phase

 

2.24            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. 

 

2.25            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 IEC of the baseline monitoring programme such that the ER can conduct on-site audit to ensure accuracy of the baseline monitoring results.

 

2.26            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 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.

 

2.27            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.

 

2.28            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.

 

 

Operational Phase

 

2.29            One year prior to the commissioning of the Project, a programme to monitor odour patrol at the identified monitoring locations shall be undertaken.

 

2.30            The measured results at ASRs will serve as the baseline data set prior to the commissioning of the Project.  These will be compared with the results obtained during the impact monitoring stage.

 

2.31            In addition, the following information shall be obtained:

 

·              Meteorological conditions from the nearest Hong Kong Observatory’s Weather Station (including temperature, wind speed, relative humidity) during the monitoring;

·              Whether any abnormal operations were being carried out at the monitoring site during the monitoring.

 

2.32            The baseline monitoring events shall be carried out every three months at the same locations within the year before the Project commissioned.

Impact Monitoring

Construction Phase

 

2.33            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 IEC of the impact monitoring programme such that the IEC can conduct on-site audit to ensure accuracy of the impact monitoring results.

 

2.34            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.

 

2.35            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.

 

Operational Phase

 

Odour Measurement at Exhaust Stacks of Deodorization System of SCISTW

 

2.36            Odour measurement for all the exhaust stacks of the deodorization system at SCISTW should be conducted with an aim to determine the total odour emission rates from the deodorization system.  The measured total odour emission rate should be used to compare with the estimated total mitigated odour emission rate as presented in the EIA Report. 

 

2.37            Odour gaseous sample should be collected by using an odour sampling system, which includes a battery-operated air pump, a sampling vessel, and an odour bag.  The odour emission rate should be determined by forced-choice dynamic olfactometer (Olfactomat-n2) in accordance with the European Standard Method (EN13725).  The ET shall propose the detailed measurement method for approval by the ER and agreement by the IEC.

 

2.38            The odour measurement shall be conducted in the first five years upon commissioning of the expanded SCISTW.  Odour measurement shall be conducted every three months for the first year of operation for the expanded SCISTW.  The first odour measurement shall be conducted within one month after operation of the expanded SCISTW.  Subsequent odour measurement shall be conducted at the 4th, 7th and 10th month.  For the 2nd to 5th year, if the measurement results indicate that the measured total odour emission rate is lower than 90% of the estimated total mitigated odour emission rate stated in the EIA Report, the frequency of the impact measurement could be reduced to once every 6 months subject to EPD’s approval.

 

Odour Patrol

 

2.39            Odour monitoring in the form of odour patrol shall be conducted by the ET.  The monitoring shall not be conducted on rainy days.  Hourly meteorological conditions (temperature, wind speed & direction, humidity) shall be recorded throughout the monitoring period.

 

2.40            Odour patrol shall be conducted by independent trained personnel / competent persons patrolling and sniffing around the Air Sensitive Receiver to detect any odour at the concerned hours.

 

2.41            The odour impact monitoring programme shall be conducted in the first five years upon commissioning of each upgraded PTWs and expended SCISTW.  Odour impact monitoring shall be conducted every three months for the first year of operation for all upgraded PTWs and expended SCISTW.  The first odour monitoring shall be conducted within one month, after the operation of the upgraded PTWs and expended SCISTW.  Subsequent odour monitoring shall be conducted at the 4th, 7th and 10th month.  For the 2nd to 5th year, if the monitoring results are below the action levels, the frequency of the impact monitoring could be reduced to once every 6 months subject to EPD’s approval. 

 

2.42            The independent trained personnel / competent persons shall :

 

·              have their individual odour threshold of n-butanol in nitrogen gas in the range of 20 to 80 ppb/v required by the European Standard Method (EN 13725).

·              be at least 16 years of age and willing and able to follow instructions.

·              be free from any respiratory illnesses.

·              be engaged for a sufficient period to build up and monitor/detect at several monitoring location;

·              not be allowed to smoke, eat, drink (except water) or use chewing gum or sweets 30 min before and during odour intensity analysis;

·              take great care not to cause any interference with their own perception or that of others by lack of personal hygiene or the use of perfumes, deodorants, body lotions or cosmetics;

·              not communicate with each other about the results of their choices.

 

2.43            At least three independent trained personnel / competent persons shall be selected to form an odour panellist to conduct the odour patrol, who should participate in a set of screening tests.

 

2.44            Subject to the prevailing weather forecast condition, odour intensity analysis shall be conducted by independent trained personnel / competent persons at the downwind locations. During the analysis, the sequence should start from less odorous locations to stronger odorous locations.

 

2.45            The perceived odour intensity is to be divided into 5 levels which are ranked in the descending order as follows:

 

0 - Not detected. No odour perceived or an odour so weak that it can not be easily characterised or described;

1 - Slight identifiable odour, and slight chance to have odour nuisance;

2 - Moderate identifiable odour, and moderate chance to have odour nuisance;

3 - Strong identifiable, likely to have odour nuisance;

4 - Extreme severe odour, and unacceptable odour level.

 

2.46            The independent trained personnel / competent persons shall record the findings including odour intensity, odour nature and possible odour sources, and also the local wind speed and direction at each location.  In addition, some relevant meteorological data such as daily average temperature, daily average humidity, wind speed and direction on that surveyed day shall be obtained from the Hong Kong Observatory Station for reference.

 

2.47            If the monitoring results are below the action levels at the last year of the monitoring programme, the impact monitoring would be ceased.  If exceedance of odour intensity of 2 is recorded at the last year of monitoring programme, investigation shall be conducted to determine the potential odour source and the corresponding departments/parties for follow up monitoring (such as continue the monitoring programme until the odour intensity of below 2 is measured) and rectification of the odour problem.  Monitoring shall not be conducted on rainy days.  Hourly meteorological conditions (temperature, wind speed & direction, humidity) shall be recorded throughout the monitoring period. 

 

Odour Complaint Registration

 

2.48            In the event when an odour complaint is received at the PTWs and SCISTW, operator shall liaise with the complainant and a Complaint Registration Form shall be completed.  The Complaint Registration Form is to record detailed information regarding the odour complaint and hence, facilitates efficient investigation work.  The registration form shall contain, but not be limited to the following information:

 

·              Location of where the odour nuisance occurred, including whether the odour was experienced indoors or outdoors;

·              Date and time of the complaint and the nuisance event;

·              Description of the complaint, i.e. the type and characteristics of the odour; and an indication of the odour strength (highly offensive / offensive / slightly offensive / just continuously detectable /intermittently detectable); and

·              Name and contact information of the complainant.

 

 

2.49            This information shall be obtained by the plant engineer or his representative(s) of the PTWs and SCISTW when the complaint is received.  The Complaint Registration Form is shown in Appendix B2 for reference.

 

2.50            In addition, the following information shall be obtained:

 

·              Meteorological conditions from the nearest Hong Kong Observatory Weather Station (including temperature, wind speed and direction, relative humidity) at the time of the complaint; and

·              Whether any abnormal operations were being carried out at the PTWs and SCISTW at the time the nuisance occurred.

 

2.51            The Odour Complaint Register shall be kept at the PTWs and SCISTW.

Environmental Quality Performance Limits

2.52            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 and odour criteria.  Table 2.3 shows the air quality criteria, namely Action and Limit levels to be used.

Table 2.3          Action / Limit Levels for Air Quality

Parameters

Action

Limit

24-hour TSP Level in mg m-3

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

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

260mg m-3

1-hour TSP Level in mg m-3

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

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

500mg m-3

Odour Nuisance

·              When two documented complaint are received; or

·              Odour Intensity of 2 is measured from odour patrol; or

·              Measured total odour emission rate from exhaust stacks of deodorization system at SCSITW ≧ 0.9 x Total mitigated odour emission rate presented in EIA Report

·        Five or more consecutive genuine documented complaints within a week; or

·        Odour Intensity of 3 or above is measured from odour patrol; or

·        Measured total odour emission rate from exhaust stacks of deodorization system at SCISTW ≧ Total mitigated odour emission rate presented in EIA Report

 

Event and Action Plan

2.53            Should non-compliance of the air quality criteria occur, actions in accordance with the Action Plan in Tables 2.4 and 2.5 shall be carried out. 

 

Table 2.4          Event / Action Plan for Construction Air Quality

Event

Action

ET

IEC

ER

Contractor

 

ACTION LEVEL

1.    Exceedance for one sample

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

2.      Inform IEC 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 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.

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.

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 IEC, EPD and ER informed of the results.

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.

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 IEC 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 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.

1.      Check monitoring data submitted by ET;

2.      Check Contractor’s working method;

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

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

5.      Supervise the implementation of remedial measures.

1.       Confirm receipt of notification of failure in writing;

2.       Notify Contractor;

3.       In consolidation 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.

1.    Take immediate action to avoid further exceedance;

2.    Submit proposals for remedial actions to IEC 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.

 

Table 2.5          Event/Action Plan for Operation Air Quality Monitoring

Event

Action

Person-in-charge of Odour Monitoring

DSD

ACTION LEVEL

Exceedance of action level 

1. Identify source/reason of exceedance;

2. Repeat odour patrol to confirm finding;

3. Repeat odour measurement at exhaust stacks of deodorization system of SCISTW (if exceedance at SCISTW) to confirm finding

1. Carry out investigation to identify the source/reason of exceedance.

  Investigation shall be completed within 2 week;

2. Implement more mitigation measures if necessary.

LIMIT LEVEL

Exceedance of Limit level 

1. Identify source / reason of exceedance;

2. Repeat odour patrol to confirm finding;

3. Repeat odour measurement at exhaust stacks of deodorization system of SCISTW (if exceedance at SCISTW) to confirm finding

4. Increase monitoring frequency to monthly;

5. If exceedance stops, cease additional monitoring.

1. Carry out investigation to identify the source/reason of exceedance. Investigation shall be completed within 2 week;

2. Rectify any unacceptable practice;

3. Formulate remedial actions;

4. Ensure amended working methods and remedial actions properly implemented;

5. If exceedance continues, consider what mitigation measures shall be implemented.

 

 

 

Mitigation Measures

Construction Phase

 

2.54            It is recommended that the requirements of the Air Pollution Control (Construction Dust) Regulation shall be adhered to during the construction period.  In addition, good site practices and a comprehensive dust monitoring and audit programme are recommended to minimise cumulative dust impacts.  Control measures relevant to this Project are listed below:

 

·             Skip hoist for material transport should be totally enclosed by impervious sheeting;

·             Vehicle washing facilities should be provided at every vehicle exit point;

·             The area where vehicle washing takes place and the section of the road between the washing facilities and the exit point should be paved with concrete, bituminous materials or hardcore;

·             Where a site boundary adjoins a road, streets or other areas accessible to the public, hoarding of not less than 2.4 m high from ground level should be provided along the entire length except for a site entrance or exit;

·             Regular watering, with complete coverage, to reduce dust emissions from exposed site surfaces and unpaved roads, particularly during dry weather;

·             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 should be applied to aggregate fines;

·             Open stockpiles should be avoided or covered.  Where possible, prevent placing dusty material storage piles near ASRs;

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

·             Control of vehicle speed on unpaved site roads.  Ten kilometers per hour is the recommended limit;

·             Every stock of more than 20 bags of cement should be covered entirely by impervious sheeting placed in an area sheltered on the top and the 3 sides;

·             Every vehicle should be washed to remove any dusty materials from its body and wheels before leaving the construction sites; and

·             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.

 

2.55            In order to achieve the air quality criteria, the following watering measures for specific site would be required to control the fugitive dust impacts:

 

·             Watering twice per day within the worksites at North Point PTW, Wan Chai East PTW, Fung Mat Road Site, Sandy Bay PTW, Wah Fu PTW, Aberdeen PTW and SCS worksite at Aberdeen;

·             Watering 4 times per day within worksites at the Central PTW;

·             The barging points should be continuous watering throughout the whole unloading process; and

·             Watering 8 times per day within worksites at the SCS works area at Wan Chai East and North Point, SCISTW and the Disinfection Facilities of SCISTW.

 

2.56            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.

 

Operational Phase

 

2.57            The fully covered design of the odour sources of the upgraded PTWs & SCISTW and the installation of deodorization system at the exhaust of ventilation system would adequately control potential odour impact.  Adverse odour impact from the PTWs & SCISTW is not anticipated.

 

2.58            In addition, good housekeeping practices for the SCISTW and PTWs listed below should be followed to ameliorate any odour impact from the plant and these standard practices should be included in the plant operator manual.

 

·             Screens should be cleaned regularly to remove accumulated organic debris;

·             Grit and screening transfer systems should be flushed regularly with water to remove organic debris and grit;

·             Grit and screened materials should be transferred to closed containers to minimize odour escape;

·             Scum and grease collection wells and troughs should be emptied and flushed regularly to prevent putrefaction of accumulated organics;

·             Skim and remove floating solids and grease from primary clarifiers regularly;

·             Sludge should be frequently withdrawn from tanks to prevent the production of gases;

·             Sludge cakes should be transferred to closed containers; and

·             Sludge containers should be flushed with water regularly.

 

2.59            Besides, in order to avoid excessive extraction of the foul air from the drop shafts of the sedimentation tanks and also the effluent flume structure of SCISTW to deodorization system, the extraction vent(s) of the deodorization system should be located away from the top openings of the drop shafts.

 

2.60            The odour impact from sludge transfer tanks could be controlled by properly design and good cleaning practices of the sludge transfer tanks.  The loading opening of sludge transfer tank is the potential odour source during the transportation when there are gaps between the tank opening and its cover.  DSD has issued a contract for the refurbishment works of the sludge transfer tanks and works are scheduled to be completed in early 2008.  The first few lots of refurbished sludge tanks should be deployed for transporting sludge to the SENT Landfill since more sensitive receivers would be encountered during the road transportation.  The air-tightness of the refurbished sludge tanks has been proved by DSD through trial tests.  With thorough cleaning practice and regular condition test of the refurbished sludge tanks, odour emission and leachate leakage during storage and transportation are not anticipated.  Further assessment and performance tests on the sludge tanks with regards to potential odour emissions would be conducted under the future EM&A programme for verification and monitoring purposes.

 

2.61            The implementation schedule for the mitigation measures during construction phase and operational phase is presented in Appendix A.