4 AIR QUALITY IMPACT ASSESSMENT

4.3 Introduction to Cremation and Air Pollution Control Technology

Introduction to Cremation Technology

4.3.1 Cremation is widely adopted in Hong Kong as a means to dispose of the dead. In general, cremation is a process of burning the dead body at high temperature to decompose organic matters and thus incombustible ash and bone materials remain after the cremation process. A complete cremation normally takes about 2 to 2.5 hours. During cremation, exhaust flue gas containing air pollutants is discharged into the atmosphere. In recent years, cremators are designed with two combustion chambers, namely the primary chamber and the secondary chamber, to enhance the combustion efficiency and reduce air pollutant emissions. Cremators with single combustion chamber are outdated and not acceptable according to the up-to-date environmental requirement.

4.3.2 Nowadays, cremators of flat-bed type and free-falling type are most commonly available in the market. These are widely adopted because of their high combustion efficiency. Higher combustion efficiency of new cremators help to decompose organic matters more completely, hence reduction in air pollutants emissions, minimizing dark smoke, dioxin and odour emissions from chimneys could be achieved.

4.3.3 Flat-bed cremator usually consists of a furnace slide door, a cremation chamber (primary combustion chamber), an afterburning chamber (secondary combustion chamber), a cease-burning chamber and an ash cooling zone. The combustion chambers are usually made of high quality fire-bricks and insulating materials including shaped bricks. The quality materials are selected according to the different thermal, chemical and mechanical requirements.

4.3.4 The main combustion chamber and the afterburning chamber are located upon each other in a compact construction way with optimum heat exchange between the combustion chambers.

4.3.5 For free-falling cremators, the cremains will “fall” from the primary combustion chamber at high level to the cremains collection chamber at a lower level. In order to accommodate the free-falling cremators, a two-storey building is required. When the cremain is transferred to the secondary combustion chamber, another coffin can be fed into the primary chamber for cremation. The operations of the primary and secondary combustion chambers are independent.

4.3.6 Therefore streamlined operation of the cremator is possible and the efficiency of cremation is improved.

4.3.7 The newly built Kwai Chung Crematorium is equipped with 4 units of free-falling cremators provides an example of new cremation technology that could be adopted in the new Diamond Hill Crematorium. However, the final selection of cremation technology for the new Diamond Hill Crematorium would be subject to the tendering process. Nevertheless, the emission limits of air pollutant emissions from the new crematorium as specified in the existing Best Practical Means for Incinerators (Cremator) published by EPD (BPM 12/2) and the target emission levels as listed in Table 4.1 would be adopted in the design specifications of the new cremators. The air pollutant emission limits as stipulated in the existing BPM 12/2 and the target emission levels of the New Crematorium are as follows:

Table 4.1 Air Pollutant Emission Limited as Stipulated in the Existing BPM 12/2

and the Target Emission Levels of the New Crematorium

Air Pollutants	Unit	Emission Limit of Existing BPM 12/2	Target Emission Levels of the New Crematorium
Particulate matters	mg/m³	100	100
Hydrogen chloride	mg/m³	100	100
Carbon monoxide	mg/m³	100	100
Total organic carbon	mg/m³	20	20
Mercury	mg/m³	-	0.2 ^(a)
Sulphur dioxide	mg/m³	-	180 ^(a)
Nitrogen Oxides (NOx as NO₂)	mg/m³	-	380 (NOx) ^(a)
Dioxins	ng I-TEQ/m³	1.0	1.0

Note : The emission limits are corrected to 273 K, 101.325 kPa, dry and oxygen 11%

^(a) Crematorium Operation and Emissions, Cemetery and Funeral Services Information Sheet, Ministry of Public Safety and Solicitor General, British Columbia, Canada

Other major design requirements of the new cremators as stipulated by BPM 12/2 aresummarized as follows:

l Cremators shall have a secondary combustion chamber. Sufficient secondary air shall be supplied to cremators in order to maintain good combustion efficiency;

l The combustion temperature of the secondary combustion chamber shall be maintained at least 850°C (at all time) and the residence of gas shall not be less than 2 seconds;

l The oxygen level of flue gas shall be greater than 6%;

l The current requirement of linear efflux velocity at chimney is not less than 7 m/s. However, a more stringent requirement linear efflux velocity not less than 15 m/s would be adopted for the new cremators.

The above design requirements of the new cremators would enhance combustion efficiency, hence to reduce emission of air pollutants. Further the dispersion of air pollutant emissions would be much improved by emission through high chimneys.

Introduction to the Available Air Pollution Control Technology

4.3.8 The flue gas emissions from the New Crematorium would have the most significant environmental impact to the general public. Air pollutants such as particulate matters, heavy metals, organic gases, acidic gases, dioxins, etc, would be emitted from the New Crematorium. Dioxins is highly toxic and is a suspected carcinogen to humans. Special air pollution control systems shall be installed to reduce the emissions of these air pollutants to acceptable levels.

4.3.9 As the final design of the New Crematorium is not yet available, the air pollution control technology for the New Crematorium is not yet confirmed. However, applicable air pollution control technologies to control the emissions from cremators are discussed below:

Wet Scrubbing

4.3.10 The principle of wet scrubbing is to remove air pollutants in flue gas through dissolution and chemical absorption by the scrubbing solution. The scrubbing solution may be water or other chemical solutions. Sodium hydroxide solution, acidified potassium permanganate, hypochlorite and other acidic solutions are common scrubbing solutions for air pollution control.

4.3.11 The flow direction of flue gas is arranged counter flow to the scrubbing solution to enhance the absorption efficiency. The cleaned flue gas is emitted to the atmosphere through the discharge while the scrubbing solution may be recycled or discharged as waste solution.

Carbon Injection

4.3.12 Carbon injection is a common air pollution control technology to remove organic air pollutants in flue gas. Fine charcoal power is injected into the flue gas ducting and organic air pollutants in flue gas are adsorbed by the charcoal power. The fine charcoal power is then collected with bag filter. Carbon injection is commonly adopted to control the emissions of dioxins. This is a dry air pollution control process.

Neutralization with Chemical

4.3.13 Neutralization is required if the flue gas is highly acidic or alkaline. For acidic gases, neutralization is accomplished by spraying of lime or soda lime solution to the flue gas. On the other hand, inorganic acids are usually used to neutralize highly alkaline flue gas. Spray nozzle or jet nozzles are usually used to spray neutralizing solution to the flue gas stream. This is a dry air pollution control process.

Electrostatic Precipitation

4.3.14 Electrostatic precipitators are usually used to collect fine particulate matters in flue gas. The equipment maintains a several kilowatt electric field to charge up fine particulates. Then the charged particulates are collected with the following oppositely charged collector plates. Electrostatic precipitators are highly efficient in collecting fine particulates. Collected dust is easily handled and disposed of to waste facilities.. This is a dry air pollution control process.

Bag Filters

4.3.15 Bag filters are also commonly used equipment to control particulate emissions. Particulate matters are collected with the filter medium. The filter bags may be made of cotton or fabric material. Filter bags shall be cleaned up regularly to avoid clogging. This is a dry air pollution control process.

Quenching

4.3.16 Quenching is a specific air pollution technology to control dioxin emissions. This is to reduce the temperature of the flue gas in a short period of time to avoid the formation of dioxins molecules. When the flue gas is cooled down to about 400 to 600°C (the dioxin “formation window”), atoms of carbon, oxygen, hydrogen and chlorine will re-combine to form dioxins molecules, which is the most thermodynamically favourable chemical species. Quenching is to cool down the flue gas suddenly, to shorten the time expose to the “formation window” and so to avoid the formation of dioxins. Quenching is usually achieved by drawing in a large amount of fresh air or spraying of water.

Air Pollution Control Technology to be Adopted by the New Crematorium

4.3.17 The newly built Kwai Chung Crematorium installed cyclone and bag filter, and is using dry chemical process for controlling the stack emission. This air pollutant control system is performing satisfactorily to reduce air pollutant emission as there is no complaint received since the operation of the Crematorium, and the stack emission test results during testing and commissioning met all the requirements of BPM 12/2. It could be referenced in the selection of the appropriate air pollution control system for the New Crematorium in Diamond Hill. However, the final selection of the air pollution control system for the New Crematorium would be subject to the tendering process but dry process will be adopted for air pollution control.

4.4 Description of the Nearby Environment

4.4.1 This sub-section describes the background information, the nearby environment and the air sensitive receivers which might be affected by the construction and operation of the New Crematorium and the demolition of the Existing Crematorium.

Geographic Conditions of the Site

4.4.2 The proposed site is located at the existing Diamond Hill Crematorium at Po Kong Village Road, Diamond Hill, Kowloon. The north to the southeast side of the crematorium is the Diamond Hill Urn Cemetery on the hillside. The closest housing estate is about 200 m at the south of the site. A school village, which consists of 5 primary and secondary schools, is located at about 200 m west of the site. There are several schools at about 300 m to the northwest of the Crematorium; and a nunnery, Chi Lin Nunnery, is located about 500 m south of the Crematorium. Residential buildings are located northwest and southeast to the Crematorium.

Background Ambient Air Quality

4.4.3 The proposed site is located at urban residential area in Kowloon. The background ambient air quality as summarized in Table 4.2 is adopted for the air quality assessment due to the operation of the New Crematorium:

Table 4.2 Background Air Pollutant Levels Adopted for Air Quality Assessment

Pollutant	Unit	Background Concentration
RSP	µg/m³	60 ⁽¹⁾
CO	µg/m³	1,051 ⁽²⁾
SO₂	µg/m³	21 ⁽¹⁾
NO₂	µg/m³	59 ⁽¹⁾
Hg	µg/m³	0.00022 ⁽³⁾
Dioxin	pg I-TEQ/m³	0.055 ⁽²⁾

Note: (1) Guidelines on Assessing the 'TOTAL' Air Quality Impacts, HKEPD

(2) Annual air pollutant concentrations in Tsuen Wan, Air Quality in Hong Kong 2001, HKEPD

(3) Annual Hg concentration in Tsuen Wan, Air Quality in Hong Kong, 2000, HKEPD

Air Sensitive Receivers

4.4.4 Air sensitive receivers (ASR) within the study area were identified based on the nature and use of the premises/facilities. Furthermore, ASRs were also identified according to the latest Outline Zoning Plan and Outline Development Plan. Sensitive locations in the future developments were also identified as ASR. The representative air sensitive receivers are summarized in Table 4.3.

Table 4.3 Details of the ASRs

ASR ID	Air Sensitive Receiver	Building Height (no. of floor)	Distance from Crematorium (m)	Angle, From North (Degree)	Elevation, mP.D.
A1	The Salvation Army William Booth Secondary School	6	316	322	84.1
A2	Tak Oi Secondary School	6	422	313	85.2
A3	Po Leung Kuk No. 1 W. H. Cheung Collage	6	272	315	87.4
A4	Heep Woh College	6	369	305	83.5
A5	Tsz Wan Shan Catholic Primary School	8	381	290	85.6
A6	Po Leung Kok Celine Ho Yam Ho Tong College	8	406	270	85.6
A7	St. Patrick Catholic Primary School	8	313	261	85.6
A8	Po Leung Kok Grandmont Primary School	8	237	270	85.6
A9	(New school under construction)	8	234	292	85.6
A10	Fu Yan Hse	20	188	160	61.0
A11	Fu Lai Hse	20	291	165	61.0
A12	Fu Shun Hse	22	234	145	61.0
A13	S.K.H. Kei Sum Primary School	6	313	136	61.0
A14	King Pik Hse (Blk B)	33	406	140	64.4
A15	Blk E, King Shan Court	33	453	153	61.5
A16	The HK Sea Cadet Corp Centre	2	150	140	62.2
A17	Staff Quarter for Diamond Hill Crematorium	2	78	120	60.4
A18	Grand View Garden (Blk 1)	39	297	180	39.7
A19	Grand View Garden (Blk 6)	28	422	192	39.7
A20	Grand View Garden (Blk 3)	35	391	175	38.3
A21	Hong Kong School For The Deaf	3	406	195	37.8
A22	Chi Lin Nunnery	3	438	200	31.4
A23	Park over the Diamond Hill No. 2 Fresh Water Reservoir (under planning)	0	156	210	84.0
A24	Diamond Hill Funeral Parlour	4	156	315	79.0

The locations of the ASRs are shown in Figure 4.1.

Existing and Future Construction Projects Near the Site

Diamond Hill No. 2 Freshwater Service Reservoir

4.4.5 The Diamond Hill No. 2 Freshwater Service Reservoir is under construction currently. The site of the Service Reservoir is located at about 156 m to the southwest of the Crematorium and the construction works would continue up to the end of 2005. Landscape works would commence upon completion of the service reservoir works. The future land use of the site will be a park and open space.

KCRC Shatin to Central Link

4.4.6 The KCRC Shatin to Central Link is under planning stage currently. The proposed railway between Tsz Wan Shan Station and Diamond Hill Station of the Shatin and Central Link would be built about 800 m to the west of the Crematorium. At this moment, the final alignment of the track is not yet confirmed, the work schedule of the new railway is also not available but it is anticipated that the construction works would delay and to be completed in 2008 or later.

4.5 Methodology of the Air Quality Assessment

Background Information of the Construction Works of the Project

4.5.1 The proposed works for the reprovisioning of the Diamond Hill Crematorium would last for about 38months, between September 2004 and November 2007. The construction would be divided into 2 phases in order to ensure continuity of cremation services to the publicduring the entire works period. Table 4.4 summarizes the tentative work programme of the Project.

Table 4.4 Tentative Work Schedule of the Project

Duration	Description	Activity Concerned
9/2004 – 2/2006	Phase I Building works for new cremators and service halls	Site formation, demolition of the existing CLP substation, building works, installation major E&M components
3/2006 – 5/2006	Commissioning and operation of new cremators	Testing and Commissioning Operation
10/2006 – 11/2007	Phase II Decommissioning of the Existing Crematorium and construction of the remaining facilities for the New Crematorium	Demolition of the Existing Crematorium, building works for the remaining facilities

Construction Works of Phase I

4.5.2 The major impacts to the ASRs during Phase I construction works would be fugitive dust emissions from the site formation, demolition of the existing CLP secondary substation and building works. It is anticipated that fugitive dust would be generated from excavation, foundation works, site clearance, material handling and wind erosion.

4.5.3 The Industrial Source Complex Short-Term, (ISCST3) developed by USEPA was employed to assess the potential fugitive dust impact to the ASRs due to the construction works. The assessment was based on the emission factors from the USEPA Compilation of Air Pollution Emission Factors (AP-42), 5^th Edition, January 1995. General construction activities and wind erosion of open sites were considered to be the major dust emission sources.

4.5.4 The dust emission rate of general construction activities is determined based on 30 working days a month, 12 working hours a day, while the dust emission rate of wind erosion is determined based on 365 days a year, 24 hours a day. In addition, for conservative prediction, dust control measures were not applied to wind erosion dust. The dust emission factors adopted for the air quality assessment are summarized in Table 4.5.

Table 4.5 Dust Emission Factors Adopted for the Air Quality Assessment of the Phase I Construction Works

Activities

Dust Emission Factors ⁽¹⁾

Dust Emission Rates for Air Dispersion Modelling

General construction activities

2.69 Mg/hectare/month

(Section 13.2.3)⁽¹⁾

2.076 x 10^-4 g/m²/s

Wind erosion of open site

0.85 Mg/hectare/year

(Table 11.9.4)⁽¹⁾

2.695 x 10^-6 g/m²/s

Note: (1) Compilation of Air Pollutant Emission Factors, USEPA AP-42, 5^th Edition, January 1995

4.5.5 The whole year of 2000 meteorological data at the Hong Kong Observatory in Tsim Sha Tsui was used for the air quality impact assessment. The hourly data of wind direction, wind speed, stability class, temperature and mixing height were collected.

4.5.6 Whole year of 2000 meteorological data collected at the Hong Kong Observatory in Tsim Sha Tsui were input for the modelling work. Although the nearest anemometer station to the site is located at ex-Kai Tak airport, the Consultant considered that the meteorological data collected by the Headquarters of Hong Kong Observatory in Tsim Sha Tsui (TST) is more representative than that of Kai Tak Anemometer Station. The considerations are summarized as follows:

a. The TST meteorological station is located in busy urban area, which is surrounded by high-rise buildings. The geographical conditions are similar to the Diamond Hill Crematorium, which is also surrounded by many buildings including schools, high-rise residential blocks and other buildings. On the other hand, the Kai Tak anemometer station is located at the end of the ex-airport runway and there is an open area with no hill and building. The topography of the Kai Tak Station is not similar to the Crematorium;

b. The distances between the Crematorium and TST and the Kai Tak Station are similar, just 5.3 km and 4.8 km respectively, there is no significant difference in distance.

c. The meteorological data recorded at the TST Hong Kong Observatory Headquarters are more complete and representative for a facility located in Kowloon urban area, as compared with Kai Tak anemometer station.

4.5.7 Based on the above discussion, the Consultant considered that the meteorological data collected at TST Hong Kong Observatory Headquarters are more representative for air quality assessment for the New Crematorium.

4.5.8 According to Guidelines on Assessing the ”Total” Air Quality Impacts, issued by HKEPD, the background TSP level of 98 mg/m³was adopted for assessment of cumulative impact.

Commissioning and Operation of New Crematorium

4.5.9 The major impact to the ambient air quality during the commissioning and operation of New Crematorium would be the chimney emissions from the cremators. During cremation, a number of air pollutants and odour would be emitted to the atmosphere through the chimneys.

4.5.10 The Consultants have checked that there was no other chimney emission source identified within 500 m radius of the Crematorium. Therefore the air quality impact assessment is based on the Cremator emissions only. It was noticed that there are two ventilation buildings of the Tate’s Cairn Tunnel (TCT) located within the 500 m study area, the cumulative air quality may be affected if the ventilation buildings are air pollution emission sources. The Consultant has consulted the operator of the TCT and noted that the ventilation buildings are for delivering fresh air into the TCT most of the time. Therefore it is concluded that the ventilation buildings are not significant air pollutant emission sources and were not taken into account in the cumulative impact.

4.5.11 The Existing Crematorium would still be operating to serve the public during the testing and commissioning of the new cremators. However, special arrangement would be made to ensure there would be no more than six cremators in operation at any time (no more than 6 of both existing and new cremators will be in operation at the same time) during this period to avoid additional loading of chimney emissions to the environment.

4.5.12 The impact of air pollutant emissions from the chimneys during operation of the New Crematorium would be evaluated by air dispersion modelling technique.

Concerned Air Pollutants

4.5.13 The major concerned air pollutants are included in the air quality impact assessment to evaluate the impact of the chimney emissions to the ASRs. These include :

- Respirable suspended particulates (RSP)

- Hydrogen chloride (HCl)

- Carbon monoxide (CO)

- Total organic compounds (TOC)

- Sulphur dioxide (SO₂)

- Nitrogen dioxide (NO₂)

- Mercury (Hg)

- Dioxins

In addition, the impact of odour and excessive cancer risk due to the operation of the New Crematorium would be assessed.

Air Quality Acceptable Criteria

4.5.14 The air quality acceptable criteria for the study was established by adoption of Hong Kong Air Quality Objective, relevant Technical Memoranda issued by EPD and other ambient air quality guidelines established by WHO and other overseas governments. The acceptable air quality criteria adopted in this study are summarized in Table 4.6.

Table 4.6 Acceptable Air Quality Criteria of the Air Quality Impact Assessment

Air Pollutant	Unit	Air Quality Acceptable Criteria
Air Pollutant	Unit	1-hour average	24-hour average	Annual Average
Total suspended particulates	mg/m³	500 ⁽¹⁾	260 ⁽²⁾	80 ⁽²⁾
Respirable suspended particulates	mg/m³	(not established)	180 ⁽²⁾	55 ⁽²⁾
Hydrogen chloride	mg/m³	2,100 ⁽³⁾	(not established)	20 ⁽⁴⁾
Carbon monoxide	mg/m³	30,000 ⁽²⁾	10,000 ⁽²⁾ (8-hr average)	(not established)
Sulphur dioxide	mg/m³	800 ⁽²⁾	350 ⁽²⁾	80 ⁽²⁾
Nitrogen dioxide	mg/m³	300 ⁽²⁾	150 ⁽²⁾	80 ⁽²⁾
Mercury	mg/m³	1.8 ⁽³⁾	(not established)	1 ⁽⁵⁾
Dioxins (2378 TCDD equivalent)	pg I-TEQ/m³	(not established)	(not established)	1 ⁽⁶⁾

Note : The air pollutant concentrations are corrected to 25°C and 101.325 kPa

Reference : ⁽¹⁾ Technical Memorandum of Environmental Impact Assessment Ordinance, HKEPD

⁽²⁾Hong Kong Air Quality Objective

⁽³⁾Reference Exposure Limits, Office of Environmental Health Hazard Assessment, California, USA

⁽⁴⁾ Integrated Risk Information System, USEPA

⁽⁵⁾WHO Air Quality Guideline, World Health Organization, 1999

⁽⁶⁾Primary Ambient Air Quality Standard for Dioxin, Department of Environmental Protection, State of Connecticut, USA, http://dep.state.ct.us/air2/regs/mainregs.htm

Design of the Cremators

4.5.15 The proposed New Crematorium would replace the Existing Crematorium in Diamond Hill, with 6 new cremators(a) to replace the 6 existing ones. The new cremators would be operated daily during normal working hours between 9:30 and 19:30. The capacity of 4 out of the 6 cremators would be 170 kg and 250 kg for the remaining 2 cremators. The total operating capacity will be about 0.7 tonne/hour when all the cremators are in full load operation. The burning fuel of the new cremators would be light diesel. With the advancement in the recent cremation technology and the strict control of the quality of diesel according to local legislative requirements, the performance and exhaust emissions of diesel-fueled cremators will fully comply with the BPM 12/2 and other environmental requirements.

4.5.16 The flue gas volumetric flow rate of the 170 kg and 250 kg cremators are 2500 m³/hour (at 6.3% oxygen, 15.5% moisture, 200°C) and 4600 m³/hour (at 11% oxygen, 12.7% moisture, 200°C) respectively as referenced to the design of the new Fu Shan Crematorium as stipulated in the EIA Report for the Fu Shan Crematorium.

4.5.17 The height of the chimney for the cremators is designed at 28.5 m above ground level. It is estimated that the temperature of the flue gas discharge after passing through the pollution control system would be 120°C at an efflux velocity of 15 m/s. The chimney diameters would be 0.22 m and 0.30 m for 170 kg and 250 kg cremators respectively.

4.5.18 The new cremators would each consist of a primary and a secondary combustion chamber. The temperature of the secondary chamber would be over 850°C during cremation and the residence time would be at least 2 seconds. Appropriate air pollution control system would be installed at the outlet of the cremator to remove excessive air pollutants including dioxins prior to discharge. Although the final selection of cremators and air pollution control system would depend on the final selection in open tendering procedure, the performance and specifications of the new cremators must comply fully with the BPM 12/2 published by EPD. It is noted that the design and technology adopted by the new Kwai Chung Crematorium would be referenced when preparing the open tender.

Air Quality Impact Assessment

Calculation of Air Pollutant Emission Rates

4.5.19 According to the BPM 12/2, the emission rates of particulates, hydrogen chloride, carbon monoxide, TOC and dioxins are regulated. The maximum air pollutant emission rates are calculated based on the maximum allowed emission concentration as tabulated in Table 4.7. The target emission levels of nitrogen oxides (380 mg/m³), sulphur dioxide (180 mg/m³) and mercury (0.2 mg/m³) are adopted for the air pollution impact assessment.

Air pollutant emission rate = emission standard x flue gas emission rate

Table 4.7 Calculation of Emission Rates of Air Pollutants

Parameter	Emission Rate Guideline mg/m³	Emission rate, g/s
Parameter	Emission Rate Guideline mg/m³	170 kg cremator	250 kg cremator
Particulates (regarded as 100% RSP)	100 ⁽³⁾	0.04994	0.06439
Hydrogen chloride	100 ⁽³⁾	0.04994	0.06439
Carbon monoxide	100 ⁽³⁾	0.04994	0.06439
TOC	20 ⁽³⁾	0.00999	0.01288
SO₂	180 ⁽⁴⁾	0.08990	0.1159
NO₂	380 ⁽⁴⁾	0.03796	0.04894
Mercury	0.2 ⁽⁴⁾	0.0000999	0.0001288
Dioxins (expressed as 2,3,7,8-TCDD equivalent)	1 ng I-TEQ/m³ ⁽³⁾	0.4994 x 10^-9	0.6439 x 10^-9

Notes : (1) Note : The emission limits are corrected to 273 K, 101.325 kPa, dry and oxygen 11%

(2) Volumetric flow rates of 1,798 and 2,318 m³/hour at reference conditions are adopted for 170 kg and 250 kg cremators respectively

(3) Emission limits as stipulated in the current BPM standard.

(4) 20% of nitrogen oxides are assumed to be present as NO₂ in this study. The emission limits for SO₂, NO_x and mercury of 180 mg/m³, 380 mg/m³ and 0.2 mg/m³ are adopted from the Ministry of Public Safety & Solicitor General, British Columbia, Canada – Crematorium Operations and Emissions (Canada).

Air Dispersion Modeling Prediction

4.5.20 The air quality impact assessment of the chimney emissions was carried out with the Industrial Source Complex Short-Term, (ISCST3) developed by USEPA. The ISCST3 is accepted by EPD for air impact assessment in Hong Kong. Concentrations of respirable suspended particulates (assuming that 100% particulate emission from the chimneys is RSP), SO₂, NO₂, CO, HCl, TOC, Hg and dioxins at the area within the radius of 500 m of the proposed chimney were estimated by ISCST3.

Assessment of Health Risk

4.5.21 The major health risk arising from the operation of the Crematorium would be due to the emissions of toxic air pollutants (TAP). The most representative TAP emissions from the chimney would be dioxins. The California Air Resources Board (CARB) identified that the unit cancer risk factor of dioxins (expressed as 2,3,7,8-TCDD equivalent) associated to lifetime exposure of 70 years is 38 (mg/m³)^-1. The excess cancer risk is calculated by multiplying the excessive annual dioxin concentration contributed by the New Crematorium at the ASR with the unit cancer risk factor. The excess cancer risk should aim at not significant level according to Table 3.3.

Odour Assessment

4.5.22 Odour has been one of the environmental concerns of the Existing Crematorium. A number of complaints on odour emissions from the existing facility were received by EPD. An odour assessment was carried out for the New Crematorium by ISCST3 to determine the odour impact.

4.5.23 To estimate the odour level in the New Crematorium, estimation was made with reference to the odour level at Kwai Chung Crematorium. A measurement of odour emission from the new Kwai Chung Crematorium was taken during the commissioning test in January 2003. Three separate 15-minute average odour levels of the flue gas emission were measured. The odour measurement was carried out by the Odour Laboratory of the Hong Kong Polytechnic University. The maximum 15-minute average odour level of flue gas emission was 325 odour unit (OU). The odour measurement report is enclosed in Appendix A4

4.5.24 As the newly built Kwai Chung Crematorium is equipped with up-to-date cremators and air pollution control system, it passed all the acceptance criteria of the testing and commissioning test including stack emission measurement, it fulfilled all the requirements of BPM 12/2. It is considered that the facility could be a good reference example to the future Diamond Hill Crematorium. Also the odour measurement was conducted during commissioning test where the cremators were running at design conditions, the operation of cremators and air pollution control system, including lime injection system and bag filter system were in normal operation at the design conditions. So the odour measurement at Kwai Chung Crematorium is considered representative of the likely odour level of the new Diamond Hill Crematorium. Furthermore, while the Kwai Chung Crematorium is operating for a certain period, the cremators and air pollution control system will be in the most optimum conditions, the odour emission will be further reduced. Therefore, the odour measurement results is representative to a worse conditions than that of normal operation.

4.5.25 The odour emission rates of the new cremators were calculated based on the volumetric flow rates of the new cremators at 25°C and the maximum odour concentration of 325 OU. The odour emission rates are exhibited in Table 4.8

Table 4.8 Calculation of Emission Rates of Odour

Parameter

Average Odour Conc. Of Flue Gas

(OU)⁽¹⁾

Emission rate, (OU-m³/s) ⁽²⁾

170 kg cremator

250 kg cremator

Odour

325

142.2

261.6

Note: (1)Measurement Report of the Odour Emissions from the Kwai Chung Crematorium in January 2003, HKPU

(2) The emission rates are calculated based on the conditions of odour analysis at laboratory, i.e. 298 K and 1 atmospheric pressure which are the same as the testing condition of the odour measurement was carried out at laboratory. The flue gas volumetric flow rates were calculated as 1575.4 m³/hour for 170 kg cremators and 2898.5 m³/hour for 250 kg cremators respectively

4.5.26 The odour assessment was carried out with ISCST3 model at different stability classes of the meteorological data, namely A&B, C, D and E&F separately. The odour level predicted by the ISCST3 model can actually be equated to 15-minute average. This assumption made by Engel et al (1997) is widely adopted. The 5-second odour average is calculated by conversion of 15-minute average to 3-minute average with a conversion factor, and then the 5-second average odour is then calculated by multiplying the 3-minute average with a second conversion factor to 5-second. The conversion factors are summarized below:

Stability Class	Conversion Factor from 15-minute to 3-minute average	Conversion Factor from 3-minute to 5-second average	Overall Conversion Factor from 15-minute to 5-second average
Class A,B	2.23	10	22.3
Class C	1.70	5	8.5
Class D	1.38	5	6.9
Class E,F	1.31	5	6.55

4.5.27 The acceptable air quality criterion for 5-second average odour exposure at the ASRs should not exceed 5 OU.

Decommissioning of the Existing Crematorium and Phase II Building Works

4.5.28 The major air quality impact of Phase II building works would be fugitive dust emission similar to Phase I. Phase II work would consist of the demolition of the Existing Crematorium and then building of other facilities of the New Crematorium. The assessment of fugitive dust impact is similar to Phase I construction work and the assessment methodology is referenced to the S. 4.5.2 through 4.5.8. The dust emission rates and the site area adopted for the assessment are summarized in Table 4.18.

4.5.29 In addition, if dioxin deposition is found at the interior surface of the chimney, flue gas piping and combustion chambers of cremators, special demolition method would be adopted to avoid fugitive emission of dioxins-contaminated materials in the environment during the decommissioning of the Existing Crematorium. The management of special demolition waste should refer to Section 7. In order to confirm whether the interior wall of the existing chimney and combustion chambers of cremators, confirmatory test would be carried out to collect deposition samples for analysis when the facility is shut down.

4.6 Results of the Air Quality Impact Assessment

Construction Works of Phase I

Maximum Impact to the Air Quality Due to the Phase I Construction Works

4.6.1 The impact of fugitive dust emissions from Phase I construction works was assessed by ISCST3. The data input and assumptions of the ISCST are listed as below:

Table 4.9 Data Input for ISCST Analysis – Phase I Construction Work

Item	Descriptions
Area of the Phase I site	40 m x 55 m (Southern half of the site)
No. of working hours	7:00 – 19:00, Monday to Saturday
Emission factor	2.69 Mg/hectare/month 0.85 Mg/hectare/year
Dust emission rate	2.076 x 10^-4 g/m²/s (general construction activities) 2.695 x 10^-6 g/m²/s (wind erosion)
Source of meteorological data	Duration : Whole year of 2000, hourly data Meteorological station : HK Observatory in TST Height of anemometer : 42.0 mA.G.
Surface roughness	0.5 m

4.6.2 The highest levels of 1-hour and 24-hour TSP levels (for both unmitigated and mitigated conditions) at the 24 ASRs in ambient air during the construction phase are summarized in Table 4.10. Under mitigated conditions where sufficient water spraying is applied to the construction site with an assumed dust control efficiency of 90%, the 1-hour and 24-hour average TSP levels at all the ASRs meet the air quality acceptable criteria under mitigated condition. According to literature, when sufficient water spraying is applied during the construction work, the fugitive dust generated from general construction dust would be reduced by 90%(c)^{, (d)}. The control of fugitive dust by water spraying is applicable to dust generated from general construction activities but not for wind erosion dust as water spray is not applied in night time and holidays. In the air quality impact assessment, the dust control efficiency for wind erosion dust is set to zero. Contour plots of fugitive dust level under mitigated and unmitigated conditions are shown in Figure 4.2 through Figure 4.5.

4.6.3 In evaluating the fugitive dust impact with dust control measures with 90% efficiency, the dust emission rate of general construction activity as listed in Table 4.9 was multiplied by 0.1 to obtain the controlled dust emission rate. The TSP level at each ASR is added with the background level of 98 mg/m³ to evaluate the residual TSP levels at ASRs.

Table 4.10Fugitive Dust Impact to the ASRs at 1.5 m above ground due to the Phase I Construction Work

ASR ID	Fugitive Dust Impact, mg/m³ (Unmitigated)		Fugitive Dust Impact, mg/m³ (Mitigated)
ASR ID	1-hr TSP	24-hr TSP	1-hr TSP	24-hr TSP
Air Quality Acceptable Criteria	500	260	500	260
A1	291	139	120	99
A2	206	121	110	99
A3	346	151	126	99
A4	260	133	116	99
A5	241	130	114	100
A6	227	126	112	99
A7	289	139	119	100
A8	395	162	131	102
A9	424	168	134	102
A10	482	181	141	102
A11	299	141	120	100
A12	382	159	130	102
A13	281	137	118	100
A14	219	124	112	100
A15	199	120	109	99
A16	629	212	157	106
A17	1260	348	228	112
A18	291	139	119	100
A19	210	122	111	99
A20	225	125	112	99
A21	218	126	111	99
A22	205	121	110	99
A23	600	206	154	103
A24	723	232	168	102

Notes : (1) TSP background level of 98 mg/m³ was included

(2) Based on the air dispersion modelling results, the maximum TSP levels are found at 1.5 m above ground at each of the ASR.

4.6.4 The residual TSP level at the ASRs will meet the respective acceptable air quality criteria when proper dust control measures are implemented.

Cumulative Impact Including Background due to the Nearby Projects

4.6.5 The Diamond Hill No. 2 Freshwater Service Reservoir would be under construction between July 2002 and the end of the 2005. The works would consist of excavation work, concrete works for the super-structure and landscape work. During Phase I construction work of the New Crematorium, excavation work for the service reservoir construction would have been completed and concreting work would be carried out. On the other hand, the KCRC Shatin Central Link project is now under planning stage and the project is likely to delay. As the construction site will be about 800 m away from the Crematorium and are far away from the air sensitive receivers, it is anticipated that the dust emission from the work site would be minimal and therefore the cumulative impact to the nearby ASRs would be mainly due to Phase I construction work of the Crematorium as discussed in above paragraphs. It is expected that the cumulative impact including background due to nearby projects would not be significant and the dust level would comply with applicable air quality acceptable criteria.

Testing and Commissioning of the New Crematorium

4.6.6 During the testing/commissioning of the newly built cremators, FEHD would implement managerial arrangement to ensure that no more than 6 cremators (no more than 6 of both existing and new ones) are in operation. The combination of the operation of the existing and new cremators would be variable and quantitative air quality assessment on testing stage could not be conducted due to lack of emission data from existing cremators. Please refer to S. 4.6.35 – 4.6.41 for further details. Nevertheless, as the new cremators are designed and built with advanced cremation and air pollution control technology, air pollutants emitted from new cremators would be much improved as compared with the existing cremators. The emission of air pollutants during the testing stage would be improved as compared with the existing condition when all the 6 existing cremators are operating. Details of the operation of the Existing Crematorium please refer to Table 4.17.

4.6.7 During commissioning test of the new cremators, human dead body with coffin would be put to cremation under specific test conditions. Since the commissioning test would be carried out similar to typical cremation process, FEHD will limit the total number of cremators in operation, including both existing and new cremators, to no more than 6 at any time. For example, when two units of new cremators are under commissioning test, no more than 4 existing cremators would be available for service.

4.6.8 When the New Crematorium is under commissioning test, training on operation of the cremator system would be provided to the responsible staff to ensure proper operation of the system. Furthermore, the operation of the air pollution control system and monitoring equipment would be tested and evaluated as well.

Operation of the New Crematorium

4.6.9 The major air quality impact to the nearby environment during the operation of the new cremators would be the chimney emissions from the Crematorium. An air quality assessment was carried out with air quality modelling technique.

4.6.10 ISCST3 developed by US Environmental Protection Agency was employed for the air dispersion modelling work. The following assumptions were made:

Table 4.11 Data Input for ISCST3 Modelling Work

No. of Cremator	170 kg Cremator x 4	250 kg cremator x 2
Efflux velocity	15 m/s
Stack exit diameter	0.22 m	0.30 m
Exit temperature of flue gas	120 ^oC
Elevation (mP.D.)	72.5 m
Stack height	28.5m (101 m.P.D.)
Fuel of Cremators	Light Diesel

Air Quality Impact Assessment Results

4.6.11 The predicted maximum concentrations of concerned air pollutants at the ASRs are summarized in Table 4.12.

4.6.12 The air quality acceptable criteria for RSP, carbon monoxide, nitrogen dioxide and sulphur dioxide are adopted from the Hong Kong Air Quality Objective. For the air quality acceptable criteria for hydrogen chloride, mercury and dioxins, the risk assessment health value, air quality guidelines established by WHO, USEPA, California government and other overseas governments are adopted for the study. The acute inhalation exposure reference is adopted as 1-hour concentration limit and the chronic inhalation exposure reference is adopted as annual average concentration limit respectively.

4.6.13 According to the air modelling results at ASRs, the worst hit level (height above ground) of different air pollutants of 1-hour average and 24-hour average are determined. Contour plots of various air pollutants on ground level, worst hit levels of 1-hour average and 24-hour average exposure are prepared and shown in Figure 4.10 through 4.30. The air quality assessment results show that the worst hit levels of 1-hour and 24-hour average exposure are at 61.5 mA.G. and 58.5 mA.G. respectively.

4.6.14 The annual averages of AQO pollutants (i.e. RSP, SO₂ and NO₂) are mainly dominated by background levels and hence only the short-term impacts (i.e. hourly and daily average) of these AQO pollutants were presented. As the New Crematorium will be equipped with advanced air pollution control system, the emissions of air pollutant will be much reduced compared with the Existing Crematorium. With the reduction of air pollutant emissions, the background air pollutant levels would be gradually improved. In the long run, the ambient air quality at the nearby area would be improved.

Table 4.12Maximum Air Quality Impact at the 24 ASRs

Air Pollutant	RSP (mg/m³)		Carbon monoxide (mg/m³)				Hydrogen Chloride (mg/m³)				Nitrogen Dioxide (mg/m³)				TOC (mg/m³)
Averaging Period	24-hour		1-hour		8-hour		1-hour		Annual		1-hour		24- hour		1-hour		24-hour
*Acceptable Criteria* ASR	*180*		*30,000*		*10,000*		*2,100*		20		*300*		*150*		--		--
*Acceptable Criteria* ASR	*Conc*	*mA.G.*	*Conc*	*mA.G.*	*Conc*	*mA.G.*	*Conc*	*mA.G.*	*Conc*	*mA.G.*	*Conc*	*mA.G.*	*Conc*	*mA.G.*	*Conc*	*mA.G.*	*Conc*	*mA.G.*
A1	64	1.5	1091	1.5	1059	1.5	40	1.5	0.1	1.5	89	1.5	62	1.5	8.0	1.5	0.88	1.5
A2	62	1.5	1074	1.5	1056	1.5	23	1.5	0.0	1.5	77	1.5	61	1.5	4.7	1.5	0.45	1.5
A3	65	1.5	1102	1.5	1061	1.5	51	1.5	0.1	1.5	98	1.5	63	1.5	10.3	1.5	1.05	1.5
A4	63	1.5	1082	1.5	1058	1.5	31	1.5	0.1	1.5	83	1.5	61	1.5	6.3	1.5	0.52	1.5
A5	62	1.5	1081	1.5	1057	1.5	30	1.5	0.2	1.5	82	1.5	61	1.5	6.2	1.5	0.41	1.5
A6	64	1.5	1095	25.5	1058	1.5	44	25.5	0.7	1.5	93	25.5	62	1.5	9.1	25.5	0.77	1.5
A7	68	19.5	1117	25.5	1066	25.5	66	25.5	1.3	1.5	109	25.5	65	1.5	13.5	25.5	1.64	25.5
A8	68	1.5	1145	25.5	1068	1.5	94	25.5	1.9	1.5	130	25.5	65	1.5	19.3	25.5	1.66	25.5
A9	65	1.5	1107	1.5	1065	1.5	56	1.5	0.5	1.5	102	1.5	63	1.5	11.6	1.5	1.01	1.5
A10	71	58.5	1218	61.5	1079	61.5	167	61.5	0.7	55.5	186	61.5	67	58.5	33.3	61.5	2.14	58.5
A11	68	61.5	1133	61.5	1065	61.5	82	61.5	0.3	55.5	121	61.5	65	61.5	16.3	61.5	1.56	61.5
A12	68	58.5	1164	61.5	1071	55.5	113	61.5	0.4	55.5	145	61.5	65	58.5	22.6	61.5	1.55	58.5
A13	62	19.5	1075	19.5	1057	19.5	24	19.5	0.1	19.5	77	19.5	61	19.5	5.0	19.5	0.42	19.5
A14	62	55.5	1097	55.5	1057	55.5	47	55.5	0.1	49.5	94	55.5	61	55.5	9.3	55.5	0.45	55.5
A15	63	61.5	1082	55.5	1058	1.5	31	55.5	0.2	49.5	83	61.5	61	61.5	6.2	55.5	0.61	49.5
A16	64	7.5	1074	7.5	1064	7.5	23	7.5	0.2	7.5	77	7.5	62	7.5	4.8	7.5	0.90	7.5
A17	61	7.5	1059	7.5	1063	7.5	8	7.5	0.0	7.5	65	7.5	59	7.5	1.8	7.5	0.12	7.5
A18	64	79.5	1130	79.5	1062	79.5	79	79.5	0.2	79.5	119	79.5	62	79.5	15.8	79.5	0.90	79.5
A19	63	79.5	1095	79.5	1059	79.5	44	79.5	0.1	79.5	92	79.5	61	79.5	8.8	79.5	0.52	79.5
A20	63	79.5	1101	79.5	1058	79.5	50	79.5	0.2	79.5	97	79.5	61	79.5	10.0	79.5	0.56	79.5
A21	62	13.5	1062	13.5	1055	13.5	11	13.5	0.1	13.5	68	13.5	60	13.5	2.3	13.5	0.39	13.5
A22	62	1.5	1061	13.5	1054	13.5	10	13.5	0.1	13.5	67	13.5	60	1.5	2.0	13.5	0.31	1.5
A23	68	1.5	1122	1.5	1072	1.5	71	1.5	0.7	1.5	113	1.5	65	1.5	15.0	1.5	1.76	1.5
A24	68	13.5	1116	13.5	1065	13.5	65	13.5	0.2	13.5	108	13.5	65	13.5	13.7	13.5	1.61	13.5

Note: (1) Assuming the particulate emissions from the chimney are all RSP

(2) The background level of RSP (60 mg/m³), carbon monoxide (1,051 mg/m³) and NO₂ (59 mg/m³) were included

Table 4.12Maximum Air Quality Impact at the 24 ASRs (Con’t)

Air Pollutant	Sulphur Dioxide (mg/m³)				Mercury (mg/m³)				Dioxins (pg I-TEQ/m³)		Excess cancer risk (per 1,000,000)
Averaging Period	1-hour		24-hour		1-hour		Annual		Annual		Excess cancer risk (per 1,000,000)
Acceptable Criteria ASR (Elevation, m)	*800*		*350*		*1.8*		*1.0*		*1.0*		*100*
Acceptable Criteria ASR (Elevation, m)	*Conc*	*mA.G.*	*Conc*	*mA.G.*	*Conc*	*mA.G.*	*Conc*	*mA.G.*	*Conc*	*mA.G.*	*Risk Level*	*mA.G.*
A1	92	1.5	29	1.5	0.08	1.5	0.000	1.5	0.056	1.5	0.02	1.5
A2	63	1.5	25	1.5	0.05	1.5	0.000	1.5	0.055	1.5	0.01	1.5
A3	120	13.5	30	1.5	0.11	1.5	0.000	1.5	0.056	1.5	0.03	1.5
A4	77	1.5	26	1.5	0.07	1.5	0.000	1.5	0.056	1.5	0.03	1.5
A5	76	1.5	25	1.5	0.06	1.5	0.001	1.5	0.057	1.5	0.09	1.5
A6	101	25.5	28	1.5	0.09	25.5	0.002	1.5	0.062	1.5	0.28	1.5
A7	139	25.5	36	25.5	0.14	25.5	0.003	1.5	0.068	1.5	0.51	1.5
A8	189	25.5	36	25.5	0.20	25.5	0.004	1.5	0.074	1.5	0.72	1.5
A9	122	1.5	30	1.5	0.12	1.5	0.001	1.5	0.060	1.5	0.20	1.5
A10	322	61.5	40	58.5	0.35	61.5	0.002	55.5	0.062	55.5	0.25	55.5
A11	168	61.5	35	61.5	0.17	61.5	0.001	55.5	0.058	55.5	0.11	55.5
A12	225	61.5	35	58.5	0.24	61.5	0.001	55.5	0.059	55.5	0.14	55.5
A13	64	19.5	25	19.5	0.05	19.5	0.000	19.5	0.056	19.5	0.05	19.5
A14	105	55.5	25	55.5	0.10	55.5	0.000	49.5	0.056	49.5	0.05	49.5
A15	77	55.5	27	61.5	0.07	55.5	0.003	49.5	0.057	49.5	0.06	49.5
A16	63	7.5	29	7.5	0.05	7.5	0.001	7.5	0.057	7.5	0.09	7.5
A17	35	7.5	22	7.5	0.02	7.5	0.000	7.5	0.055	7.5	0.01	7.5
A18	162	79.5	29	79.5	0.16	79.5	0.005	79.5	0.057	79.5	0.09	79.5
A19	100	79.5	26	79.5	0.09	79.5	0.003	79.5	0.056	79.5	0.05	79.5
A20	111	79.5	26	79.5	0.10	79.5	0.003	79.5	0.057	79.5	0.06	79.5
A21	42	13.5	24	13.5	0.02	13.5	0.000	13.5	0.056	13.5	0.04	13.5
A22	39	13.5	24	1.5	0.02	13.5	0.000	13.5	0.056	13.5	0.03	13.5
A23	148	1.5	36	1.5	0.15	1.5	0.002	1.5	0.062	1.5	0.28	1.5
A24	138	13.5	35	13.5	0.14	13.5	0.001	13.5	0.057	13.5	0.06	13.5

Note: (1) The background level of SO₂ (21 mg/m³), Hg (0.00022mg/m³) and dioxins (0.055 pg I-TEQ/m³) were included

4.6.15 The detailed results of the air quality impact assessment are enclosed in Appendix A2 and contour plots showing the air quality levels in the vicinity are enclosed in the Figures 4.10 through 4.30.

4.6.16 The contour plots showing the 1-hour average of NO₂ at 61.5 mA.G., (as shown in Figure 4.17) shows that the 1-hour average NO₂ at some area at the level of 61.5 mA.G. exceed the air quality acceptable criteria. However, it is noted that the affected areas are in mid air and there is no high-rise building nor ASR within the affected area in mid air. If ASR A17 (which falls within the footprint of the exceedance zone but currently is a 2-storey structure) is to be redeveloped, the future development may subject to adverse air quality impact should it be redeveloped to high rise building. Though there is currently no plan for its redevelopment, in order to identify the possible future development constraints, a separate modeling was conducted to predict the 1-hour NO₂ concentration at various elevations. According to the air quality modelling results as shown in Appendix A5 and the required additional safety margin of 10 m (ref : Guidelines on Estimating Height Restriction and Position of Fresh Air Intake Using Gaussian Plume Models”, HKEPD), the maximum heights for re-development of ASR A17 is recommended not to exceed 36.5 mA.G. to avoid the impact of NO₂ due to the operation of the New Crematorium. The above height restriction is recommended based on the air quality assessment results of this EIA report. Whenever re-development of ASR A17 is required, it is suggested that the future developer should conduct a special air quality assessment at the planning stage to evaluate whether the recommended height restriction at the location is still applicable regarding the chimney emissions and the ambient air quality at that time.

4.6.17 Comparing the predicted concentrations including background concentrations of each air pollutant with the relevant ambient air quality standards, there is no significant impact to the ambient air quality and the operation of the Crematorium would not cause significant deterioration to the ambient air quality at the nearby ASRs.

Health Risk Assessment

4.6.18 A health risk assessment was carried out by evaluating the excess cancer risk due to exposure to dioxins at the ASRs. The excess cancer risk assessment was carried out by multiplying the unit cancer risk factor (38 (mg/m³)^-1) with the highest annual dioxin concentration in ambient air due to emissions from the cremators.

4.6.19 Referring to the air quality assessment results, the highest annual dioxins concentration would increase by 0.019 pg I-TEQ/m³(0.074 – 0.055 = 0.019 pg I-TEQ/m³). The excess cancer risk is therefore calculated to be 0.72 x 10^-6, which is lower than the significant risk level of 100 x 10^-6(See Table 4.13). The cancer risk associated with the operation of the Crematorium is not significant at all the ASRs.

Table 4.13Increased Risk to Lifetime Exposureof 70 years to Dioxins

	Cancer Risk
Maximum annual dioxins level at air sensitive receiver A8	0.074 – 0.055 = 0.019 pg I-TEQ/m³
Maximum excess cancer risk (A8)	0.019 x 38 x 10^-6 0.72 x 10^-6
Cancer risk impact	Not significant

4.6.20 For inventory purpose, the emission of dioxins from the New Crematorium is calculated as follows:

Annual emission of dioxins

Emission concentration x volumetric flow rate x 10 hours x 365 days

1.0 ng/m³ x (1,798 m³/hr x 4 + 2,318 m³/hr x 2) x 10 hours x 365 days

43.2 mg I-TEQ/year

4.6.21 The estimated annual emission of dioxins from the New Crematorium is 43.2 mg I-TEQ per year.

Odour Assessment

4.6.22 Based on the operational experience of the old style cremators or waste incinerators, odour emission from the chimneys may affect the nearby air sensitive receivers since such old style cremators are not equipped with appropriate air pollution control system.

4.6.23 EPD and FEHD have received a number of complaints on the emissions from the existing cremators from the general public in the past few years. The complaints are mainly related to the dark smoke emissions and the odour nuisance during the operation of the existing cremators. Odour is one of the major environmental aspect of the New Crematorium. With the adoption of advanced incineration technology and installation of effective air pollution control system, it is anticipated that emission of air pollutants from the new Cremators would be reduced to an acceptable level.

4.6.24 Since the odour emissions from cremators is a concern of the general public, an odour assessment was carried out to assess the odour impact of the New Crematorium. The assessment was carried out by ISCST3 to determine the 5-second average odour at the ASRs. The data input for the air modelling are summarized in Table 4.14

Table 4.14Data Input for ISCST3 Modelling Work for Odour Assessment

No. of Cremator	170 kg Cremator x 4	250 kg cremator x 2
Efflux velocity	15 m/s
Stack exit diameter	0.22 m	0.30 m
Odour emission rate	142.2 OU-m³/sec	261.6 OU-m³/sec
Atmosphere stability class	Class A,B Class C Class D Class E,F
Ambient temperature of at ASRs	25 ^oC
Elevation (mP.D.)	72.5 m
Stack height	28.5 m (101 mP.D.)

4.6.25 Air modelling work was carried out at different stability classes. The maximum 5-second average odour exposure is compared with the air quality acceptable criteria as specified in the EIAO TM Annex 4. The odour assessment results are summarized in Table 4.15.

Table 4.15Results of the Odour Assessment at Different Atmospheric Stability Classes

Atmosphere Stability Class	ASR with Max Odour Impact	15-minute Average Odour (OU)	Multiplying Factor	5-second Average Odour (OU)
Class A,B	A23 (1.5 m)	0.12060	22.3	2.69
Class C	A23 (1.5 m)	0.11446	8.5	0.97
Class D	A10 (55.5 m)	0.22362	6.9	1.54
Class E,F	A10 (61.5 m)	0.55358	6.55	3.63
Air Quality Acceptable Criteria – 5-second Average Odour Exposure				5
*Maximum 5-second Average Odour Exposure*				*3.63*

4.6.26 It is found that the maximum odour exposure is under the stability class E,F at 61.5 mA.G. of A10. The 5-second average odour exposure (stability class E,F) at all the ASRs is exhibited in Table 4.16. The maximum 5 second average odour exposure at all the ASRs are well below the acceptable criterion as specified in the Annex 4 of the EIAO TM and so there is no significant odour impact on the ASRs.

Table 4.16Maximum 5-second Odour Exposure at ASRs Under Stability Class E,F

ASR	1-hour Average Odour (OU)	Multiplying Factor	5-second Average Odour (OU)
Air Quality Acceptable Criterion (EIAO TM Annex 4)			5 OU over 5 seconds
A1 (19.5 m)	0.0573	6.55	0.38
A2 (19.5 m)	0.0010		0.01
A3 (19.5 m)	0.0069		0.05
A4 (19.5 m)	0.0001		0.00
A5 (25.5 m)	0.0477		0.31
A6 (25.5 m)	0.1465		0.96
A7 (25.5 m)	0.2160		1.41
A8 (25.5 m)	0.3063		2.01
A9 (25.5 m)	0.0629		0.41
A10 (61.5 m)	0.5536		3.63
A11 (61.5 m)	0.2714		1.78
A12 (61.5 m)	0.3762		2.46
A13 (19.5m)	0.0386		0.25
A14 (55.5 m)	0.1546		1.01
A15 (61.5 m)	0.1040		0.68
A16 ( (7.5 m)	0.0001		0.00
A17 (7.5 m)	0.0000		0.00
A18 (79.5 m)	0.2599		1.70
A19 (79.5 m)	0.1447		0.95
A20 (85.5 m)	0.1665		1.09
A21 (7.5 m)	0.0026		0.02
A22 (13.5 m)	0.0019		0.01
A23 (1.5 m)	0.0257		0.17
A24 (13.5 m)	0.0022		0.01

Note: (1) Figures in brackets are the levels of ASR above ground

4.6.27 The contour plotting of 5-second odour level at ground level and at 61.5 mA.G.. (worst hit level ) under the stability class E,F and at the ground level under the stability class A,B (worst hit level as well) are shown in Figures 4.29 to 4.30. The 5-second average odour level at all ASRs meet the acceptable air quality criterion of 5 OU. Although there is exceedance noted at 61.5 mA.G. under stability class E,F, it is noted that there is no high rise building within the affected area in mid air, so there is no impact to ASRs. If ASR A16 and A17 (which fall within the footprint of the exceedance zone but currently are 2-storey structures) are to be redeveloped, the future development may subject to adverse air quality impact should they be redeveloped to high rise buildings. Though there is currently no plan for their redevelopment, in order to identify the possible future development constraints, a separate modeling was conducted to predict the odour concentration at these two locations at various elevations. According to the air quality modelling results as shown in Appendix A5 and the required additional safety margin of 10 m (ref : Guidelines on Estimating Height Restriction and Position of Fresh Air Intake Using Gaussian Plume Models”, HKEPD), the maximum heights for re-development of ASR A16 and ASR A17 is recommended not to exceed 45.5 mA.G. and 36.5 mA.G. respectively. Whenever if re-development of ASR A16 and A17 is required, it is suggested that the future developer should conduct a special air quality assessment at the planning stage to evaluate whether the recommended height restriction at the locations is still applicable regarding the chimney emissions and the ambient air quality at that time.

4.6.28 Besides odour emissions from chimneys, fugitive emissions of odour from the daily operation of the Crematorium is assessed. In view of the operation of Crematorium, coffins from the general public are totally enclosed, and unclaimed dead bodies are properly packaged when delivered to the Crematorium. Coffins and other dead bodies will not be further processed until cremation. Therefore there should be no other fugitive odour emission other than the chimney emissions.

4.6.29 In order to prevent odour impact to the near ASRs, regular odour patrol will be carried out at the site boundary during the operation of the New Crematorium. Corrective actions would be carried out immediately if significant odour emission is detected by the odour patrol team.

Air Quality Assessment for the Operation of Joss Paper Burners

4.6.30 According to the planning of the New Crematorium, 4 units of joss paper burners will be installed near the service halls for Chinese memorial ceremonies. Burning of joss paper and joss stick usually generate smoke emissions. The dimensions of the joss paper burners will be 1.5 m (L) x 1.5 m (W) x 1.1 m (H). Assuming 6 cremation time slots are available a day, the duration of a typical memorial ceremony is 30 minutes and the burning material is assumed to be 2 kg per ceremony, the maximum operation time for each of joss paper burner is 3 hours a day. 12 kg of burning material will be combusted for each joss paper burner per day. This is the worst case scenario, as some memorial ceremonies do not burn joss paper and joss stick.

4.6.31 In general, joss paper burners being used nowadays are just simple combustion chamber without air pollution control, the flue gas emission may affect the nearby ASRs.

4.6.32 In order to reduce the nuisance due to the emissions from joss paper burners, administrative mitigation measures would be adopted as follows:

l FEHD will limit the use of joss paper burners. Joss paper burners will be only allowed for the use of memorial ceremonies upon request by the relatives. Other usage of joss paper burners will not be allowed;

l Guidance will be provided to the users to advise them to minimize the quantity of burning material;

l FEHD staff will advise the users to ensure better combustion of the joss paper in order to reduce smoke emission.

It is anticipated that the emission of air pollutants would be much improved by administrative management measures to reduce the usage of joss paper burners to minimal and to improve the combustion efficiency. Whenever necessary, FEHD will advice users to reduce the quantity of burning materials through proper education channels.

Comparison of the Environmental Performance with the Existing Crematorium

4.6.33 In comparing the environmental performance of existing cremators and new cremators, the following 3 different approaches, in order of preference, could be adopted:-

(a) Approach 1 - Actual measurement of air pollutant emissions (including dioxins) from the existing cremators;

(b) Approach 2 - Making reference to air pollutant emissions measurement results for other operating cremators with similar design, either locally or in overseas countries; or

(c) Approach 3 - Qualitative comparison by assessing the extent of air quality improvement that will be brought about by replacing the existing cremators with new ones.

Both Approach 1 and Approach 2 can give quantitative estimates of air pollutant emissions from the existing cremators, although strictly speaking Approach 2 is only an indication of the possible emission levels from existing cremators because there is no actual emission measurement done for the existing cremators. In comparison, Approach 3 cannot provide any quantitative estimates of air pollutant emissions from existing cremators.

4.6.34 The following paragraphs demonstrate that both Approach 1 and Approach 2 are not practicable in this EIA study and so only Approach 3 could be adopted.

Approach 1 - actual measurement of air pollutant emissions

4.6.35 The Existing Crematorium in Diamond Hill is not classified as Specified Process under the Air Pollution Control Ordinance due to the small processing capacities of the cremators (<0.5 tonne per hour). It is therefore not subject to licensing control and there is no requirement of regular air pollutant emission measurement for the existing cremators. FEHD is not in possession of relevant air pollutant emission measurement results for the existing cremators. If this approach is adopted, it is necessary to arrange stack emission test specifically for the purpose of getting actual emission levels from the existing cremators.

4.6.36 The Consultants have investigated the site and concluded that it is not practicable to carry out stack measurement due to the following constraints. FEHD also confirmed these constraints:-

- The design of the Existing Crematorium Chimney is 10 m above ground, there is an ejector fan installed inside the chimney to exhaust flue gas and no sampling facility is available to carry out stack sampling work. The existing stack for the cremators in the Existing Crematorium in Diamond Hill is not suitable for carrying out air pollutant emission sampling work because (1) there is an ejector fan in the stack which disturbs the air flow pattern, (2) there is not sufficient straight run of the stack to even out the air flow, (3) sampling could only be done along one axis instead of perpendicular axes as required in stack measurement. In conclusion, the design and facility of the Existing Crematorium failed to provide representative stack emission data.

- To overcome these constraints, it is necessary to extend the stack sufficiently long to achieve uniform air flow free of the influence of the ejector fan and to conduct the stack sampling on a temporarily erected sampling platform above the roof. Unfortunately, the existing roof could not support the additional loading of the temporary platform and so it is necessary to construct an extensive steel portal across the crematorium hall with truss supports from the ground and the truss supports will be massive concrete blocks. It is expected that this will take about six months to design the temporary structure and process the application. Furthermore, the sampling work and laboratory analysis of the collected samples will take another two months. This will affect the master programme of the Project significantly.

- Furthermore, the massive concrete support for the temporary structure for stack sampling work will obstruct the only access road to the Existing Crematorium. FEHD/Arch SD confirmed that temporary blocking of the access road, and hence temporary closure of the Crematorium, is needed to construct the structure and conduct the stack sampling. It is estimated that the Existing Crematorium has to be closed for at least four weeks to facilitate the stack sampling work. This will seriously affect the operation of the Crematorium and the normal provision of cremation service to the public will be accordingly affected.

4.6.37 In view of the above constraints, it is not practicable to get actual air pollutant emission measurement results from the existing cremators.

Approach 2 – Making reference to air pollutant emission results for other operating cremators with similar design

4.6.38 We conducted a detailed search on the availability of air pollutant emission measurement results from local or overseas cremators with similar design to the existing cremators in the Existing Crematorium in Diamond Hill. We could not find any such measurement results in overseas countries. The only available cremator emission measurement results in Hong Kong are those from (i) the Fu Shan Crematorium (Year 2001 measurement results); and (ii) the Cape Collinson Crematorium (Year 2002 measurement results)

4.6.39 Having reviewed the air pollutant emission measurement results and the design of the cremators in Fu Shan and Cape Collinson Crematoria, we concluded that these measurement results could not be used to indicate the emission levels of the existing cremators in the Existing Crematorium in Diamond Hill because of the following reasons:-

- The cremators in the Existing Crematorium in Diamond Hill are diesel-fired cremators while the cremators in Fu Shan Crematorium are gas-fired;

- Four of the cremators in the Existing Crematorium in Diamond Hill are designed with single combustion chamber only while the cremators in Fu Shan Creamtorium and Cape Collinson Crematorium are designed with both primary and secondary combustion chambers.

4.6.40 As there is no other available emission measurement results in the public domain, we conclude that there is no comparable air pollutant emission measurement data to indicate the emission levels of the existing cremators in the Existing Crematorium in Diamond Hill.

Approach 3 – Qualitative comparison

4.6.41 As both Approach 1 and Approach 2 could not be used to indicate the air pollutant emission levels of the cremators in the Existing Crematorium in Diamond Hill, it is concluded that it is not possible to quantify the emission levels of the existing cremators. Approach 3 therefore becomes the only practicable means to qualitatively compare air pollutant emission levels of the existing cremators and the new cremators to be installed in the New Crematorium in future.

The following table summarizes the comparison of the performance of the existing cremators and the future new cremators in terms of cremator design, air pollutant emissions control and monitoring practices, and crematorium management practices.

Table 4.17 Comparison of Existing and New Cremators

		Existing Cremators	Future New Cremators
Cremator Design	Combustion chambers	Primary chamber only	Primary and secondary chambers
	Combustion temperature	Around 800 ^oC	At least 850 ^oC for 2 seconds in secondary combustion chamber to ensure complete combustion
	Monitoring of sufficient combustion air in combustion zone	Not provided	Continuous monitoring by oxygen and carbon monoxide sensors in secondary chamber
Air Pollutant Emission and Monitoring	Air pollution control system	Nil	Adequate air pollution control system including cyclone, bag filter with lime and activated carbon injection will be installed to treat the flue gas before dispersion to the atmosphere. Alternative air pollution control system with equivalent performance may be installed subject to final selection in the open tender process
	Air pollutant emission monitoring	Smoke density meter to monitor smoke emission only	Smoke density at the chimney will be continuously monitored. In addition, regular stack monitoring will be conducted according to the future Specified Process Licence
	Compliance with BPM emission limits	Not applicable	Must comply with stipulated emission limits for various air pollutants including dioxin
Cremator Management Practices	Environmental management programme	Nil	Will be established and implemented to control the operation and maintenance practice of the crematorium in order to achieve better environmental performance

The above table clearly demonstrates that the future new cremators are of better design and equipped with adequate air pollution control system. They will also fully comply with all the requirements of the BPM 12/2. On the other hand, complaint of dark smoke emission and odour associated with the existing cremators are received occasionally. This shows that the existing cremators are not performing ideally in environmental perspective. Obviously, when the existing cremators are replaced by the new cremators in future, there would be substantial improvement in the air quality in the district and we expect there will not be dark smoke and odour emissions from the cremators.

Demolition of the Existing Crematorium and Phase II Building Works

Maximum Impact to the Air Quality Due to Phase II Construction Works

4.6.42 Phase II construction work would consist of the demolition of the Existing Crematorium building and building works for two service halls and other facilities of the New Crematorium. The impact of fugitive dust emissions from Phase II construction works was evaluated by ISCST3 similar to Phase I construction work. The data input and assumptions of the ISCST3 are listed as below:

Table 4.18Data Input for ISCST3 Analysis – Phase II Construction Work

Item	Descriptions
Area of the Phase II site	65 m x 75 m (Northern half of the site)
No. of working hours	7:00 – 19:00, Monday to Saturday
Emission factor	2.69 Mg/hectare/month (Section 13.2.3) 0.85 Mg/hectare/year (Table 11.9.4)
Dust emission rate	2.076 x 10^-4 g/m²/s (general construction activities) 2.695 x 10^-6 g/m²/s (wind erosion)
Source of meteorological data	Duration : Whole year of 2000, hourly data Meteorological station : HK Observatory in TST Height of anemometer : 42.0 m A.G.
Surface roughness	0.5 m

4.6.43 The 1-hour and 24-hour TSP in ambient air (for both unmitigated and mitigated conditions) at the 24 ASRs during Phase II construction work are summarized in Table 4.19. The 1-hour and 24-hour average TSP levels at all the ASRs under the mitigated conditions meet the relevant standard and air quality objective. During the construction work, water spraying would be applied to the construction site regularly according to the APCO (Construction Dust) regulation. Similar to the situation in Phase I construction work, the dust control efficiency of water spraying is 90%. Contour plots showing the ambient TSP level under unmitigated and mitigated conditions are enclosed in Figures 4.6 to 4.9.

Table 4.19Fugitive Dust Impact to the ASRs at 1.5 mA.G. due to Phase II Construction Work

ASR ID	Fugitive Dust Impact, mg/m³ (Unmitigated)		Fugitive Dust Impact, mg/m³ (Mitigated)
ASR ID	1-hr TSP	24-hr TSP	1-hr TSP	24-hr TSP
Air Quality Acceptable Guideline	500	260	500	260
A1	529	121	146	101
A2	413	113	133	100
A3	743	134	170	103
A4	463	119	139	101
A5	424	133	134	102
A6	357	126	127	101
A7	457	156	138	105
A8	650	181	160	108
A9	775	164	174	106
A10	585	147	152	124
A11	387	126	130	102
A12	517	143	145	103
A13	405	129	132	102
A14	314	119	122	101
A15	278	113	118	100
A16	755	174	171	107
A17	1245	264	226	118
A18	389	126	130	101
A19	288	112	119	100
A20	309	115	121	100
A21	300	114	120	100
A22	276	112	118	100
A23	688	153	164	105
A24	1542	307	259	123

Notes : (1) TSP background level of 98 mg/m³ was included

(2) Based on the air dispersion modelling results, the maximum TSP levels are found on the ground level (1.5 m) at each of the ASR.

4.6.44 The contour plots show that under the mitigated scenario, the construction works would not impose significant dust impact on nearby ASRs.. Therefore it is anticipated that the construction work would not impose significant impact to the nearby citizens.

Fugitive Emission of Dioxin Contaminated Dust during Decommissioning of the Existing Crematorium

4.6.45 The Existing Crematorium has been operated for more than 24 years and the interior surface of the chimney, flue gas ducting and combustion chambers may be contaminated with heavy metals and dioxins, etc. The demolition of the Existing Crematorium may generate fugitive emissions of toxic air pollutants to the atmosphere. Since the Existing Crematorium is still under normal operation, the Consultant was not able to collect samples of surface deposition to verify whether the interior surface of the chimney is contaminated with toxic air pollutants.

4.6.46 Fugitive emission of dioxin-contaminated materials during demolition of the Existing Crematorium will be a concern when the existing facility is demolished. A confirmatory test of dioxins in the depositions on chimney wall, flue gas ducting and combustion chambers will be carried out when the Existing Crematorium is shut down. Sampling of surface deposition for chemical analysiswill be arranged. If the dioxin level is between 1 and 10 ppb I-TEQ, it is classified as moderately contaminated with dioxins. The demolition work site should be covered up to avoid emission of fugitive dust during demolition. The management of demolition waste is referred to in the waste management plan as discussed in Section 7.

4.6.47 If the dioxin level exceeds 10 ppb I-TEQ, it is classified as severely dioxin-contaminated waste. If it is confirmed that the existing facilities are severely contaminated with dioxins, a special decommissioning method – Containment method – would be adopted. The principle of containment method is to enclose the whole decommissioning site with containment. The containment would be maintained at negative air pressure to prevent emission of dioxin contaminated dust into the atmosphere. The chimney would be lined with 3 layers of fire retardant polythene sheets. An air mover would be provided to maintain a negative pressure of 0.05-0.15 inches of water within the work area throughout the entire course of the decommissioning works. A pressure monitor with printout facility and audible alarm would be installed at any easily accessible location to monitor the internal pressure. Pre-filter and high efficiency air particulate filter shall be installed at the air exhausts to avoid emission of fugitive dust to the atmosphere.

4.6.48 Before the commencement of the decommissioning work, a smoke test would be carried out to ensure there is no air-leakage of the containment. The containment would be commissioned only when the smoke test is passed. When the containment is commissioned, a ventilation rate of 6 air changes per hour shall be maintained. A “dirty room”, a shower room and a “clean room” would be provided for workers to clean up before leaving the work site.

4.6.49 As the demolition waste would be carefully handled to avoid potential fugitive emission of dioxin according to the waste management practices as discussed in Section 7, it is anticipated that the fugitive emission of dioxin contaminated dust during demolition of the Existing Crematorium building would be properly controlled and the impact to the air quality would be insignificant.

Demolition and Removal of Asbestos Containing Material

4.6.50 An asbestos assessment at the Existing Crematorium in 2003confirmed that asbestos was found in the existing building structure. A registered asbestos contractor would be employed to remove asbestos containing material during the demolition of the Existing Crematorium building in accordance with the requirements of APCO in order to avoid leakage of asbestos to the atmosphere during the demolition works. An asbestos investigation report (AIR) for the demolition of the Existing Crematorium is enclosed in Appendix D. A formal AIR and Asbestos Abatement plan signed by a registered asbestos consultant shall be submitted to the Authority for approval under APCO 28 days prior to the start of any asbestos abatement work.

4.6.51 As asbestos containing material (ACM) will not be handled until the Phase II construction work in March 2006, therefore control of ACM during the Phase I construction work is not required. When ACM is handled, such as demolition and handling of demolition waste, all ACMs will be properly labelled by a registered asbestos consultant. Furthermore, staffs working at the Crematorium will be well informed of the presence of ACM and to take proper precaution. In case of any disturbance of ACM, staff of the Crematorium will seek advice from a registered asbestos consultant immediately.

4.6.52 Under the APCO, the following precautionary and mitigation measures would be taken during removal of asbestos containing materials:

o Enclosure of the work area

o Containment and sealing for the asbestos containing waste

o Provision of personal decontamination facility

o Use of personal respiratory/protection equipment

o Use of vacuum cleaner equipped with high-efficiency air particulate (HEPA) filter for cleaning up the work area

o Carrying out air quality monitoring during the asbestos abatement work

4.6.53 In addition, APCO also requires the appointment of qualified personnel to carry out the asbestos containing material removal work:

o A registered asbestos contractor to carry out the work;

o A registered asbestos supervisor to supervise the work;

o A registered asbestos laboratory to monitor the air quality, and

o A registered asbestos consultant to supervise and certify the asbestos abatement work.

4.6.54 The impact of asbestos exposure due to the decommissioning of the Existing Crematorium would be insignificant when all the above precaution and mitigation measures are taken during the demolition work.

Site Management When Handling Asbestos Containing Materials

4.6.55 The asbestos materials in each building / premises must be abated before other contractors / trades are allowed to work in the building / premises;

4.6.56 Tight security measures should be taken at the asbestos abatement work site to prevent any disturbance to asbestos materials that may be resulted from the stealing of electrical cable and copper pipes. Also, it is recommended that all friable asbestos containing materials, in this case the cloth insulation and gasket, be abated first.

4.6.57 As different contractors may be working on site at the same time, the following extra measures should be considered:

- if there is sensitive receptor around the area, conduct environmental air monitoring at this off-site sensitive receptors

- Submit to EPD a completion report, include photos and air monitoring results, immediately after completion of asbestos abatement work for each work zone

Cumulative Impact due to the Nearby Projects

4.6.58 During Phase II building works, there would be the construction work of the proposed KCRC’s Shatin to Central Link about 800 m to the west of the Crematorium. The KCRC project is now under planning stage, the final alignment of the track and detail works programme is still not available. Since the construction site is about 800 m away from the Crematorium, there are long distances to the ASRs. Therefore the cumulative impact contributed by the railway works would be insignificant.

4.7 Mitigation Measures to Reduce Adverse Environmental Impacts

4.7.1 A number of mitigation measures are proposed to relieve the air quality impact due to the construction and operational of the proposed crematorium.

Construction Works of Phase I

4.7.2 The fugitive dust emission would be the most significant impact to the air quality during Phase I Construction Works. According to the Air Pollution Control (Construction Dust) Regulation, the following mitigation measures would be implemented:

1. Erect a site barrier with the height of no less than 2.4 m at the construction site boundary to enclose the work area;

2. Apply frequent water spraying to ensure the surface of the construction site sufficiently wet to reduce fugitive dust due to wind erosion and transportation on unpaved haul road;

3. Cover up stockpiles of fill material and dusty material;

4. Install a vehicle-cleaning system at the main entrance of the construction site to clean up the vehicles before leaving the site.

4.7.3 It is expected that the fugitive dust emission would be reduced by at least 90% when the above mitigation measures are taken.

Commissioning of New Crematorium

4.7.4 In order to prevent additional loading of chimney emissions to the environment, administrative control measures would be taken to ensure that there would be no more than six cremators, including new and existing ones under commissioning test, in operation at any one time.

4.7.5 Specifically, the following testing and commissioning schedule will be adopted:

a. Commissioning test of the new cremators would be carried out one by one, with no more than 2 new cremators undergoing commissioning test at the same time;

b. The total number of operating cremators, including both new and existing cremators, would not be more than 6.

An operational log book would be maintained to record the operational time of each of the new and existing cremators.

Operation of New Crematorium

4.7.6 The proposed cremators would be designed with advanced technology in combustion as well as equipped with appropriate air pollution control system. As discussed above, the chimney emissions would not impose significant impact on the nearby environment. The most important mitigation measures would be to ensureproper operation of the Crematorium and the air pollution control system. In case of failure of any part of the cremator system, the operation should be suspended and the failure rectified as soon as possible. Furthermore, a stringent management of the New Crematorium will be implement to ensure proper operation of the facility, the areas of staff training, emission monitoring, inspection and maintenance arrangements will be strengthened.

Demolition of the Existing Crematorium and Phase II Construction Work

4.7.7 The mitigation measures for fugitive dust emissions due to the Phase II works would be similar to those adopted for Phase I. Proposed mitigation measures are referred to in S. 4.7.2.

4.7.8 If the interior deposition of the existing chimney, flue gas piping and cremation chambers are confirmed contaminated with dioxin, special demolition method would be adopted to avoid fugitive emission of dioxin contaminated dust. Special precaution method for demolition of dioxin contaminated material is discussed in S. 4.6.47 through 4.6.51 and the management of waste should refer to Section 7.

4.8 Evaluation of Residual Impacts

Construction and Demolition Phase

4.8.1 Based on the discussion of the above sections, the construction of the New Crematorium and the decommissioning of the Existing Crematorium will not impose adverse residual impact to the nearby environment when all the requirements of the Air Pollution Control (Construction Dust) Regulation are properly implemented during the construction works.

Operation Phase

4.8.2 The design of the new cremators and the emissions of air pollutants will meet the requirements of the BPM 12/2, and the air quality at the ASRs has been assessed and should satisfy the respective air quality and risk guidelines. As a result, it is anticipated that there would be no adverse residual impact due to the operation of the New Crematorium.

(a) The new cremators will be fired by light diesel with sulphur content less than 0.5% by weight and viscosity of less than 6 centistokes at 40 ^oC or better. Arch SD had considered whether to use gas-fired or diesel-fired cremators. In view of the advanced cremator design and the installation of air pollution control system to treat the flue gas from the cremators, it is expected that emissions from the diesel-fired cremators can comply with the BPM requirement and there would be no excessive dark smoke emissions. FEHD therefore decided to use diesel-fired cremators instead of gas-fired cremators.

(c) Overview of Fugitive Dust Emissions, May 2000 - Section 3, by Mary Hewitt Daly and Jennifer Franco,http://www.pirnie.com/docs/resources_pubs_air_may00_6.html

(d) Summary of Minimum Dust Control Parameter, Mine Safety and Health Administration, Pittsburgh Safety and Health Technology Centre, http://www.msha.gov/S&HINFO/TECHRPT/DUST/MINPAR.pdf

4.1.1 This Section exhibits an assessment of air quality impact from the construction, demolition and operation of the Project which may impose onthe nearby sensitive receivers.

4.3.4 The main combustion chamber and the afterburning chamber are located upon each other in a compact construction way with optimum heat exchange between the combustion chambers.

4.3.6 Therefore streamlined operation of the cremator is possible and the efficiency of cremation is improved.

4.3.9 As the final design of the New Crematorium is not yet available, the air pollution control technology for the New Crematorium is not yet confirmed. However, applicable air pollution control technologies to control the emissions from cremators are discussed below:

4.3.11 The flow direction of flue gas is arranged counter flow to the scrubbing solution to enhance the absorption efficiency. The cleaned flue gas is emitted to the atmosphere through the discharge while the scrubbing solution may be recycled or discharged as waste solution.

4.4.1 This sub-section describes the background information, the nearby environment and the air sensitive receivers which might be affected by the construction and operation of the New Crematorium and the demolition of the Existing Crematorium.

4.4.3 The proposed site is located at urban residential area in Kowloon. The background ambient air quality as summarized in Table 4.2 is adopted for the air quality assessment due to the operation of the New Crematorium:

4.5.5 The whole year of 2000 meteorological data at the Hong Kong Observatory in Tsim Sha Tsui was used for the air quality impact assessment. The hourly data of wind direction, wind speed, stability class, temperature and mixing height were collected.

4.5.7 Based on the above discussion, the Consultant considered that the meteorological data collected at TST Hong Kong Observatory Headquarters are more representative for air quality assessment for the New Crematorium.

4.5.8 According to Guidelines on Assessing the ”Total” Air Quality Impacts, issued by HKEPD, the background TSP level of 98 mg/m3 was adopted for assessment of cumulative impact.

4.5.9 The major impact to the ambient air quality during the commissioning and operation of New Crematorium would be the chimney emissions from the cremators. During cremation, a number of air pollutants and odour would be emitted to the atmosphere through the chimneys.

4.5.12 The impact of air pollutant emissions from the chimneys during operation of the New Crematorium would be evaluated by air dispersion modelling technique.

4.5.13 The major concerned air pollutants are included in the air quality impact assessment to evaluate the impact of the chimney emissions to the ASRs. These include :

Calculation of Air Pollutant Emission Rates

Air Dispersion Modeling Prediction

Assessment of Health Risk

Odour Assessment

4.5.22 Odour has been one of the environmental concerns of the Existing Crematorium. A number of complaints on odour emissions from the existing facility were received by EPD. An odour assessment was carried out for the New Crematorium by ISCST3 to determine the odour impact.

4.5.25 The odour emission rates of the new cremators were calculated based on the volumetric flow rates of the new cremators at 25°C and the maximum odour concentration of 325 OU. The odour emission rates are exhibited in Table 4.8

4.5.27 The acceptable air quality criterion for 5-second average odour exposure at the ASRs should not exceed 5 OU.

Construction Works of Phase I

4.6.1 The impact of fugitive dust emissions from Phase I construction works was assessed by ISCST3. The data input and assumptions of the ISCST are listed as below:

4.6.4 The residual TSP level at the ASRs will meet the respective acceptable air quality criteria when proper dust control measures are implemented.

4.6.9 The major air quality impact to the nearby environment during the operation of the new cremators would be the chimney emissions from the Crematorium. An air quality assessment was carried out with air quality modelling technique.

4.6.10 ISCST3 developed by US Environmental Protection Agency was employed for the air dispersion modelling work. The following assumptions were made:

4.6.11 The predicted maximum concentrations of concerned air pollutants at the ASRs are summarized in Table 4.12.

4.6.15 The detailed results of the air quality impact assessment are enclosed in Appendix A2 and contour plots showing the air quality levels in the vicinity are enclosed in the Figures 4.10 through 4.30.

Health Risk Assessment

4.6.20 For inventory purpose, the emission of dioxins from the New Crematorium is calculated as follows:

4.6.21 The estimated annual emission of dioxins from the New Crematorium is 43.2 mg I-TEQ per year.

Odour Assessment

4.6.22 Based on the operational experience of the old style cremators or waste incinerators, odour emission from the chimneys may affect the nearby air sensitive receivers since such old style cremators are not equipped with appropriate air pollution control system.

4.6.25 Air modelling work was carried out at different stability classes. The maximum 5-second average odour exposure is compared with the air quality acceptable criteria as specified in the EIAO TM Annex 4. The odour assessment results are summarized in Table 4.15.

4.6.29 In order to prevent odour impact to the near ASRs, regular odour patrol will be carried out at the site boundary during the operation of the New Crematorium. Corrective actions would be carried out immediately if significant odour emission is detected by the odour patrol team.

4.6.31 In general, joss paper burners being used nowadays are just simple combustion chamber without air pollution control, the flue gas emission may affect the nearby ASRs.

4.6.32 In order to reduce the nuisance due to the emissions from joss paper burners, administrative mitigation measures would be adopted as follows:

4.6.33 In comparing the environmental performance of existing cremators and new cremators, the following 3 different approaches, in order of preference, could be adopted:-

4.6.34 The following paragraphs demonstrate that both Approach 1 and Approach 2 are not practicable in this EIA study and so only Approach 3 could be adopted.

4.6.36 The Consultants have investigated the site and concluded that it is not practicable to carry out stack measurement due to the following constraints. FEHD also confirmed these constraints:-

4.6.37 In view of the above constraints, it is not practicable to get actual air pollutant emission measurement results from the existing cremators.

4.6.40 As there is no other available emission measurement results in the public domain, we conclude that there is no comparable air pollutant emission measurement data to indicate the emission levels of the existing cremators in the Existing Crematorium in Diamond Hill.

The following table summarizes the comparison of the performance of the existing cremators and the future new cremators in terms of cremator design, air pollutant emissions control and monitoring practices, and crematorium management practices.

4.5.8 According to Guidelines on Assessing the ”Total” Air Quality Impacts, issued by HKEPD, the background TSP level of 98 mg/m³was adopted for assessment of cumulative impact.