2.1 This section presents the requirements, methodology, equipment, monitoring locations, criteria and protocols for the monitoring and audit of air quality impacts during the construction and operational phase of the Project.
2.2 The objectives of the air quality monitoring shall be:
· to identify the extent of construction dust and operational odour impacts on sensitive receivers;
· to determine the effectiveness of mitigation measures to control fugitive dust emission from activities during construction phase and odour control measures during operational phase;
· to audit the compliance of the Contractor with regard to dust control, contract conditions and the relevant dust impact criteria;
· to recommend further mitigation measures if found to be necessary;
· to comply with Action and Limit (A/L) Levels for air quality as defined in this Manual; and
· to set up an odour complaint registration system to handle odour complaints due to TPSTW.
2.3 The criteria against which ambient air quality monitoring to be assessed are:
· The Hong Kong Air Quality Objectives (AQOs) for TSP, 24-hour TSP levels of 260 mg m-3;
· The statutory 1-hour TSP limit of 500 mg m-3; and
· 5 odour units based on averaging time of 5 seconds or equivalent H2S concentration of 2.5 ppb.
2.4 These levels are not to be exceeded at Air Sensitive Receivers (ASRs).
2.5 The locations of air sensitive receivers (ASRs) within and adjacent to the project area are shown in Figure 2.1.
Construction Phase
2.6 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 method as set out in High Volume Method for Total Suspended Particulates, Part 50 Chapter 1 Appendix B, Title 40 of the Code of Federal Regulations of the USEPA.
2.7 Dust laden air shall be drawn through a high volume sampler (HVS) fitted with a conditioned, pre-weighed filter paper, at a controlled rate. After sampling for 1 hour and 24 hours, the filter paper with retained particles is collected and returned to the laboratory for drying in a desiccator followed by accurate weighing. Respective 1-hour and 24-hour TSP levels are calculated from the ratio of the mass of particulates retained on the filter paper to the total volume of air sampled.
2.8 All relevant data including temperature, pressure, weather conditions, elapsed-time meter reading for the start and stop of sampler, identification and weight of the filter paper, and other special phenomena and work progress of the concerned site, etc, shall be recorded in detail. A sample data sheet is shown in Appendix C.
2.9 HVS in compliance with the following specifications shall be used for carrying out the 1-hour and 24-hour monitoring:
· 0.6 - 1.7 m3 per minute (20 - 60 standard cubic feet per minute) adjustable flow range;
· equipped with a timing / control device with ± 5 minutes accuracy for 24 hours operation;
· installed with elapsed-time meter with ± 2 minutes accuracy for 24 hours operation;
· capable of providing a minimum exposed area of 406 cm2 (63 in2);
· flow control accuracy: ± 2.5% deviation over 24-hour sampling period;
· incorporated with an electronic mass flow rate controller or other equivalent devices;
· equipped with a flow recorder for continuous monitoring;
· provided with a peaked roof inlet;
· incorporated with a manometer;
· able to hold and seal the filter paper to the sampler housing at horizontal position;
· easy to change the filter; and
· capable of operating continuously for 24-hour period.
Operational Phase
Hydrogen Sulphide Monitoring
2.16 H2S concentrations shall be measured by portable H2S analyser, type Jerome 631-X H2S, or equivalent. The analyser shall be able to measuring H2S concentration in the range of 1 ppb to 50 ppm, with resolution of 1 ppb. The analyzer operates within a temperature range of 0 to 40oC, at an air flowrate of 0.15 L/min. Grab air sample will be drawn by built-in suction pump of the analyzer and passed through a gold film sensor. The electrical resistance of the gold film changes according to the change in mass of hydrogen sulphide in the gas sample.
2.17 During the sampling period, meteorological data including temperature, wind speed and direction shall be obtained from the Hong Kong Observatory’s Tai Mei Tuk Weather Station.
Odour Complaint Registration
2.18 In the event when an odour complaint is received at the TPSTW, 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.
2.19 This information shall be obtained by the plant engineer or his representative(s) of the TPSTW when the complaint is received. The Complaint Registration Form is shown in Appendix C6 for reference.
2.20 In addition, the following information shall be obtained:
· Meteorological conditions from the Hong Kong Observatory’s Tai Mei Tuk Weather Station (including temperature, wind speed, relative humidity) at the time of the complaint; and
· Whether any abnormal operations were being carried out at the STW at the time the nuisance occurred.
2.21 The Odour Complaint Register shall be kept at the TPSTW.
Construction Phase
2.22 Three worst affected locations have been identified for TSP dust monitoring as shown in Table 2.1 and illustrated in Figure 2.2. Prior to the commencement of the EM&A programme, the proposed air quality monitoring stations shall be discussed and agreed with the ER, IC(E) and EPD.
Table 2.1 Air Monitoring Stations during Construction Phase
|
Identification No. |
Air Sensitive Receiver I.D. (EIA Ref.) |
Air Monitoring Location |
|
CAM1 |
AS12 |
Government Staff Quarter |
|
CAM2 |
AS9 |
Heng Hing Printing Centre |
|
CAM3 |
AS8 |
Talcon Industrial Ltd |
· monitoring at sensitive receivers close to the major site activities which are likely to have air quality impacts;
· monitoring at the air sensitive receivers as defined in the Technical Memorandum; and
· a horizontal platform with appropriate support to secure the samples against gusty wind shall be provided;
· no two samplers shall be placed less than 2 m apart;
· 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;
· a minimum of 2 m separation from walls, parapets and penthouses is required for rooftops samplers;
· a minimum of 2 m separation from any supporting structure, measures horizontally is required;
· no furnace or incinerator flue is nearby;
· airflow around the sampler is unrestricted;
· the sampler is more than 20 m from the dripline;
· any wire fence and gate to protect the sampler, shall not cause any obstruction during monitoring;
· permission must be obtained to set up the samplers and to obtain access to the monitoring stations; and
· a secured supply of electricity is needed to operate the samplers.
Operational Phase
2.25 Three Air Sensitive Receivers (ASRs) have been identified for odour monitoring as shown in Table 2.2 and illustrated in Figure 2.3. H2S measurements shall be taken at the sources and outside the premises of the identified ASRs. The level for odour monitoring shall be discussed and agreed with the DSD and EPD.
2.26 Odour monitoring shall be taken at two locations of TPSTW to obtain the H2S concentrations at sources. The selected locations are shown in Figure 2.3 and listed in Table 2.2. The monitoring shall be taken at a height of 1.5m from the surface of the sources concerned.
Table 2.2 Air Monitoring Stations during Operational Phase
|
Identification No. |
Air Sensitive Receiver I.D. / Odorous Source (EIA Ref.) |
Air Monitoring Location |
|
OAM1 |
AS12 |
Government Staff Quarter |
|
OAM2 |
AS4 |
Interpac Containers Ltd |
|
OAM3 |
AS1 |
Watson’s Water Centre |
|
OSM1 |
PRI203 |
Stage I/II Primary Sedimentation Tank |
|
OSM2 |
PRI401 |
Stage IV Primary Sedimentation Tank |
1-hr & 24-hr TSP Monitoring (Construction Phase)
2.27 Baseline monitoring shall be carried out by the ET to determine the ambient 1-hour and 24‑hour TSP levels at the monitoring locations prior to the commencement of the Project. During the baseline monitoring, there shall not be any construction or dust generating activities in the vicinity of the monitoring stations.
2.28 TSP baseline monitoring shall be carried out for a continuous period of at least two weeks under typical weather conditions with the 24-hour and three 1-hour ambient measurements taken daily at each monitoring location. General meteorological conditions (wind speed, direction and precipitation) and notes regarding any significant adjacent dust producing sources shall also be recorded throughout the baseline monitoring period.
2.29 The baseline monitoring will provide data for the determination of the appropriate Action levels with the Limit levels set against statutory or otherwise agreed limits.
2.30 Baseline checking of ambient TSP levels shall be carried out every six months at each monitoring location, when no dusty works activities are in operation. 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 air quality criteria, after consultation and agreement with the ER, the IC(E) and the EPD.
Odour (Operational Phase)
2.31 One year prior to the commissioning of Stage V Extension of STW, a programme to monitor concentrations of hydrogen sulphide (H2S) at the selected ASRs and sources shall be undertaken.
2.32 The measured results of H2S at ASRs will serve as the baseline data set prior to the commissioning of Stage V Extension. These will be compared with the results obtained during the impact monitoring stage. For the results of H2S at sources, they shall be collected as reference information for the analysis of exceedance events during the operational phase.
2.33 In addition, the following information shall be obtained:
l Meteorological conditions from the Hong Kong Observatory’s Tai Mei Tuk Weather Station (including temperature, wind speed, relative humidity) during the monitoring;
l Whether any abnormal operations were being carried out at the STW during the monitoring.
2.34 A 15-min H2S concentration should be measured every 3 hours for a duration of 24 hours at each of the monitoring locations. The purpose of sampling in 3-hour intervals and to cover a duration of a whole day is to capture the different atmospheric conditions at different time periods. If, due to insufficient monitoring equipment or monitoring personnel, monitoring can be spread to 3 to 4 consecutive days as long as the different monitoring periods and each of monitoring locations are covered. Pairwise monitoring at ASR and at source should be carried out simultaneously. However, as the variation of odour concentration at sources should be less significant, timing of sampling or monitoring within the STW should be more flexible so as to accommodate the available resources for the monitoring programme.
2.35 The baseline monitoring events shall be carried out every three months at the same locations within the year before the Stage V Extension is commissioned.
2.36 In order to gauge the most recent baseline condition before the Stage V Extension is operational, the last baseline monitoring event should be assigned at a time of 1 to 2 weeks before the actual commissioning of the Stage V Extension.
2.37 The ET Leader shall carry out impact monitoring during the course of the works. For regular impact monitoring, a 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. The impact monitoring programme is summarised in Table 2.3.
Table 2.3 Construction Phase Monitoring Programme (TSP)
|
Sampling Duration |
Frequency |
|
1 hour |
· 3 times every 6 days |
|
24 hours |
· Once every 6 days |
2.38 Before commencing the impact monitoring, the ET leader shall inform the IC(E) of the impact monitoring programme such that the IC(E) can conduct an on-site audit to ensure the accuracy of the monitoring results.
2.39 H2S measurements shall be conducted by the DSD at the same monitoring stations and levels as in the baseline period, using portable H2S analyser, type Jerome 631-X H2S, or equivalent. The analyser shall be able to measure H2S concentration in the range of 1 ppb to 50 ppm, with resolution of 1 ppb.
Table 2.4 Operational Phase Monitoring Programme (Odour)
|
Sampling duration |
Frequency |
|
24 hours |
· Once every three months for the first year after operation of each Phase of the Stage V Extension · Once every six months for the 2nd and 3rd year after operation of each Phase of the Stage V Extension |
2.42 Action and Limit (A/L) levels that provide an appropriate framework for the interpretation of monitoring results have to be agreed between ET, IC(E), EPD and the Engineer before commencement of the air quality monitoring. The air quality monitoring data shall be checked against the agreed A/L levels. Recommended A/L levels are listed in Table 2.5.
Table 2.5 Proposed Action and Limit Levels for Impact Monitoring
|
Parameter |
Action Level (1) |
Limit Level |
|
TSP (24 hour average) |
· BL £ 200 mg m-3, AL = (BL * 1.3 + LL)/2 · BL > 200 mg m-3, AL = LL |
260 mg m-3 |
|
TSP (1 hour average) |
· BL £ 384 mg m-3, AL = (BL * 1.3 + LL)/2 · BL > 384 mg m-3, AL = LL |
500 mg m-3 |
|
H2S (at ASRs only) |
· BL £ 1.92 ppb, AL = (BL * 1.3 + LL)/2 · BL > 1.92 ppb, AL = LL |
2.5 ppb |
|
Incidence of odour complaints |
Any incidence of odour complaint received through the Odour Complaint Register |
Two or more complaints through the Odour Complaint Register within three months |
(1) BL = Baseline level, AL = Action level, LL = Limit level.
2.43 The EAP is based on the prescription of procedures and actions associated with the measurement of certain defined levels of air pollution recorded by the environmental monitoring process and the agreed A/L levels. In case TSP A/L level exceedances occur, the ET, the IC(E), the Engineer and the Contractor shall observe the relevant actions of the respective EAP listed in Tables 2.6 whereas relevant sections in DSD shall be responsible for the implementation of the EAP as listed in Table 2.7 in the event of odour exceedance/complaint for construction and operational phase respectively.
Table 2.6 Event/Action Plan for Air Quality Monitoring (Construction Phase)
|
ACTION |
||||
|
ET |
IC(E) |
ER |
CONTRACTOR |
|
|
ACTION LEVEL |
||||
|
1. Exceedance for one sample |
1. Identify source, investigate the causes of complaint 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. 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 exceedance in writing; 2. Notify Contractor; 3. Ensure remedial measures properly implemented.
|
1. Submit proposals for remedial actions to IC(E) within three 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 Contractor, IC(E), ER, 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. 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 exceedance 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 three 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 exceedance 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 three 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 2.7 Event/Action Plan for Air Quality Monitoring (Operational Phase)
|
EVENT |
ACTION |
||
|
TPSTW Engineer-in-charge of Odour Monitoring |
DSD ST1 |
DSD SP / E&MP (*) |
|
|
ACTION LEVEL |
|||
|
Exceedance of action level or receipt of any odour complaint |
1. Identify source/reason of exceedance or odour complaints; 2. Repeat measurement to confirm finding. |
1. Carry out investigation to identify the source/reason of exceedance or complaints. Investigation shall be completed within 1 week; 2. Rectify any unacceptable practice; 3. Amended working methods if required; 4. Inform DSD SP/E&MP if cause of complaint or exceedance is considered to be caused by civil or E&M design problems; 5. Correspond to the complainant within 10 days to inform the cause of the nuisance and action taken; and 6. Implement amended working methods.
|
1. Assist ST1 to find the root cause of the complaint or exceedance; and 2. Modify or improve design as appropriate.
|
|
LIMIT LEVEL |
|||
|
Exceedance of Limit level or receipt of two or more complaints in 3 months |
1. Identify source / reason of exceedance or odour complaints; 2. Repeat measurements to confirm findings; 3. Increase monitoring frequency to monthly; 4. If exceedance stops, cease additional monitoring. |
1. Carry out investigation to identify the source/reason of exceedance or complaints. Investigation shall be completed within 1 week; 2. Rectify any unacceptable practice; 3. Amended working methods if required; 4. Notify DSD SP / E∓ 5. Formulate remedial actions; 6. Ensure amended working methods and remedial actions properly implemented; 7. If exceedance continues, consider what portion of the work is responsible and stop that portion of the work until the exceedance is abated; and 8. Correspond to the complainant within 10 days to inform the cause of the nuisance and action taken.
|
1. Assist ST1 to find the root cause of the complaint or exceedance; 2. Modify or improve design as appropriate; and 3. Formulate remedial actions in association with ST1.
|
Note:
(*) The role of DSD SP / E&MP would be started upon commencement of the Project and ceased one year after the commissioning of the Stage V.
2.44 The EIA Report recommended air quality control and mitigation measures during the construction and operational phases of the Project. The mitigation measures are summarised below.
2.45 Dust mitigation measures stipulated in the Air Pollution Control (Construction Dust) Regulation shall beincorporatedto control dust emission from the site. Major control measures relevant to this Project are listed below:
· skip hoist for material transport shall be totally enclosed by impervious sheeting;
· vehicle washing facilities shall 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 shall be paved with concrete, bituminous materials or hardcore;
· where a site boundary adjoins a road, streets or other accessible to the public, hoarding of not less than 2.4 m high from ground level shall be provided along the entire length except for a site entrance or exit;
· every main haul road shall be paved with concrete and kept clear of dusty materials or sprayed with water so as to maintain the entire road surface wet;
· the portion of road leading only to a construction site that is within 30 m of a designated vehicle entrance or exit shall be kept clear of dusty materials;
· every stock of more than 20 bags of cement shall be covered entirely by impervious sheeting placed in an area sheltered on the top and the 3 sides;
· all dusty materials shall be sprayed with water prior to any loading, unloading or transfer operation so as to maintain the dusty materials wet;
· every vehicle shall be washed to remove any dusty materials from its body and wheels before leaving the construction sites; and
· the load of dusty materials carried by vehicle leaving a construction site shall be covered entirely by clean impervious sheeting to ensure dust materials do not leak from the vehicle.
2.46 As recommended in the EIA Report, standard practices of good house keeping for a sewage treatment works should be included in the plant operator manual and details are summarised in Table 2.8 below:
Table 2.8 Practices for Good House Keeping
|
Location |
Good Practices |
|
Preliminary treatment processes
|
· Bar screens shall be cleaned regularly to remove any accumulated organic debris · Grit and screening transfer systems shall be flushed regularly with water to remove organic debris and grit · Grit and screened materials shall be transferred to closed containers |
|
Primary clarifier, bioreactor and final clarifier |
· Scum and grease collection wells and troughs shall be emptied and flushed regularly to prevent putrefaction of accumulated organics · Skim and remove floating solids and grease from primary clarifiers regularly · Frequent sludge withdrawal from tanks is necessary to prevent the production of gases |
|
Sludge dewatering area |
· Sludge cake shall be transferred to closed containers · Sludge containers shall be flushed with water regularly |
2.47 Odour would be released at the inlet works as a result of discharges of sewage. The turbulence induced by drops would release the odorous gas from sewage. The immediate area of turbulence: mechanical screen, grit removal and flume channel is recommended to be covered to reduce odour emission from site. Foul air underneath the covers shall be withdrawn by pumps to create a slight negative pressure, which eliminate odour leakage from seals. The foul air shall be drawn through deodorizer and discharged after treatment.
2.48 Odour emission from the Stage I/II and Stage IV primary sedimentation tanks could be controlled by covering the weir launders. Chemical addition (e.g. addition of calcium nitrate) to sewage at Tai Yuen Sewage Pumping Station No. 4 (convey sewage to Stage IV works) before sewage flowing into TPSTW Stage IV should be provided to reduce the odour strength at the inlet work, grit removal, screen house and primary sedimentation tanks.
2.49 The sludge facilities, including sludge gravity thickener, sludge consolidation tanks, a screening unit (next to dewatering house) and wet well of sludge pumping stations, should also be enclosed, to ensure no leakage of odorous gas. The foul air from the sludge gravity thickeners and sludge consolidation tanks would be discharged into atmosphere after passing through deodorizer.
2.50 It is recommended that the sludge digestion tank outlet chamber shall be covered, with the foul air treated by deodorisation units before discharging into atmosphere.
2.51 In the final sedimentation tanks, effluent and waste sludge shall be well oxidised in the clarifier, and odour shall not be generated unless there are operational problems. The two major sources of odours are scum and sludge removal system. Without proper, daily housekeeping, accumulations of scum on clarifier water surface, sludge accumulation on walls, and organic matter on effluent weir troughs can produce odours. The following measures are recommended for the final clarifiers.
· Scum scrapers, troughs, weirs and interior walls of final clarifiers shall be cleaned and flushed regularly; and
· Settled solids shall not be allowed to accumulate long enough for anaerobic conditions. Residence times not exceeding 2 hours to avoid septic conditions in the settled sludge.
2.52 Table 2.9 below summarizes the proposed control measures for the odorous facilities, outlined in this air quality assessment. The Engineer may propose alternative control measures, taking into account of constraints of the facilities, and demonstrate that equivalent mitigated H2S emission rates, listed in Table 2.9 could be achieved. Figures 2.4 and 2.5 show the proposed odour mitigation measures for Phases 1 & 2 of the Stage V Extension respectively.
Table 2.9 Proposed Control Method for Odorous Facilities
|
|
Facility |
Control Method |
|
Stage I/II
|
Inlet Pumping Staton |
Cover exposed area (IN201) (1) + deodorizer (2) (IN2) |
|
Flume channel & grit removal |
Cover exposed areas (GR201 & GR202)(1) |
|
|
Primary sedimentation tank |
Cover all weir area |
|
|
Return Activated Sludge Pumping Station |
Cover exposed area (RAS2) (1) |
|
|
Sludge digestion tank |
Cover outlet chamber (DI201)(1) + deodorizer (2) (DI2) |
|
|
Sludge gravity thickener |
Cover (1TH201, 1TH202, 2TH201 & 2TH202) (1) + deodorizer (2) (TH2) |
|
|
Sludge consolidation tank |
Cover (SOL201 & SOL202)(1) + deodorizer (2) (SOL2) |
|
|
Screening unit outside Dewatering house |
Cover (DEW202) (1) |
|
|
Sludge pumping station (wet well) |
Cover exposed area (PUMP2)(1) |
|
|
Stage IV
|
Inlet Pumping Station |
Cover (IN401) (1) + deodorizer (2) (IN4)
Chemical Dosage: Odour reduction up to 45% (Phase 1) Odour reduction up to 65% (Phase 2) |
|
Grit removal |
Cover exposed area (GR401 & GR402) (1) |
|
|
Screen House |
Chemical Dosage: Odour reduction up to 45% (Phase 1) Odour reduction up to 65% (Phase 2) |
|
|
Primary sedimentation tank |
Cover all weir area
Chemical Dosage Odour reduction up to 45% (Phase 1) Odour reduction up to 65% (Phase 2) |
|
|
Sludge digestion tank chamber |
Cover (DI401) (1) + deodorizer (2) (SODI4) |
|
|
Sludge consolidation tank |
Cover (SOL401, SOL402 & SOL403) (1) + deodorizer(2) (SODI4) |
Note: (1) Cover area refers to Figure 2.4 & 2.5.
(2) 99% Odour removal efficiency
2.54 The implementation for the recommended mitigation measures is presented in Appendix B.