3.1
This
Section presents an assessment of the potential air quality impacts associated
with the demolition of the existing crematorium, construction and operation of
the new crematorium. The air quality
impact assessment was conducted in accordance with the requirements of Annex 4
and Annex 12 of the Technical Memorandum on Environmental Impact Assessment
Process (EIAO-TM) as well as the requirements set out under Clause
Project Background
3.2 The existing Cape Collinson Crematorium has started operation since 1962. Cremator Nos. 1-10 were replaced in 1995 and Nos. 11-12 were commissioned in 2001. In order to cope with an increasing demand for cremation service, Food and Environmental Hygiene Department (FEHD) proposes to demolish the existing crematorium as well as to construct and operate a new crematorium in-situ as a replacement (hereinafter referred to as the Project).
3.3 The Project will be developed in two phases, namely Phases 1 and Phase 2. The Project Site is the site of the existing Cape Collinson Crematorium which consists of four service halls with twelve cremators. Site formation work will be carried out at the beginning of Phase 1 which involves extension of the existing car park area for the construction of an access road. After the site formation has been completed, a new crematorium with 4 cremators will be constructed to the north of the existing crematorium. During this period, all the 12 cremators in the existing crematorium will remain in operation until the satisfactory commissioning of the new cremators under Phase 1 by 2012.
3.4 As advised by the Project Proponent, the existing crematorium will still be operating to serve the public during the testing and commissioning (T&C) of the four new cremators under Phase 1. However, special arrangement will be made to control that there will be no more than ten of both existing and new cremators in operation at any time (i.e. two new cremators and eight existing cremators) during T&C period to avoid additional loading of chimney emissions to the environment. In other words, eight out of 12 existing cremators will be operated concurrently with two new cremators during T&C period of Phase 1. Details of the operating conditions during T&C period of Phase 1 would be presented in Sections 3.42 to 3.44 below.
3.5 After the satisfactory commissioning of the new cremators under Phase 1, demolition of the existing crematorium, construction of another six cremators and one service hall will then be carried out in Phase 2. No overlapping of construction/demolition works between Phase 1 and Phase 2 will occur. Phase 2 works will be completed in 2014.
3.6
A
total of ten cremators will be provided in the new crematorium. Nine cremators
will be of
3.7 Apart from the new cremators, three units of joss paper burners will be installed. Burning of the joss paper usually emits smoke which may affect the nearby environment. Therefore, the potential air quality impact arising from operation of joss paper burner is also considered in the EIA Study.
Cremation Technology
3.8
Cremation is commonly adopted in
3.9
Cremators of flat-bed type and free-falling type are
most commonly used due to their high combustion efficiency. Higher combustion
efficiency of new cremators helps decompose organic matters more completely and
hence reduction in air pollutants emissions from the cremation process.
3.10
Flat-bed cremators consist of a furnace slide door,
primary combustion chamber, secondary combustion chamber, a cease-burning
chamber and an ash cooling zone. The combustion chambers are made of high
quality fire-bricks and insulation materials. The primary and secondary chambers
are located one on top of the other in a compact configuration, achieving
optimum heat exchange between the two combustion chambers.
3.11
Free-falling cremators consist of a primary combustion
chamber at high level and a mineralization chamber at a lower level. The
“cremains” (a portmanteau of “cremated” and “remains”) will fall from the
primary combustion chamber to the mineralization chamber (cremains collection
chamber). When the cremains are transferred to the mineralization chamber,
another coffin can be fed into the primary combustion chamber for cremation.
The operations of the primary combustion and mineralization chambers are
independent.
3.12 The newly built Diamond Hill Crematorium is equipped with 6 units of free-falling cremators provides an example of new cremation technology that could be adopted in the new Cape Collinson Crematorium. Although the final selection of cremation technology would be subject to open tendering procedure, the performance and specifications of the new cremators shall fully comply with the BPM12/2(06).
Air Pollution Control
Technology
3.13 The flue gas emissions from the New Crematorium would have the most significant environmental impact to the public. The combustion process within the flue emissions from the new crematorium will generate air pollutants, such as particulate matter, heavy metals, organic gases, acidic gases, dioxins, etc. Installation of an APC equipment is required to reduce the emissions of such air pollutants to acceptable levels. Applicable APC technologies are described below.
Wet Scrubbing
3.14 Wet scrubbing removes air pollutants in flue gas through dissolution and chemical absorption by scrubbing solution. The solution may be water or other chemical solutions. Common scrubbing solutions include sodium hydroxide, acidified potassium permanganate, hypochlorite and other acidic solutions.
Carbon Injection
3.15 Carbon injection removes organic air pollutants in flue gas. Fine charcoal powder is injected into the flue gas ducting and organic air pollutants in flue gas are absorbed by the charcoal powder. The fine charcoal powder is then collected with bag filter. This technology is commonly adopted to control the emissions of dioxins and is a dry air pollution control process.
Neutralization with Chemical
3.16 Neutralization is adopted 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. Inorganic acids are usually used to neutralize highly alkaline flue gas. Spray nozzle or jet nozzle is usually used to spray neutralizing solution to the flue gas system. This is a dry air pollution control process.
Electrostatic
Precipitation
3.17 Electrostatic precipitators are used to collect fine particulate matters in flue gas. The electrostatic precipitator maintains an electric field of several kilowatts to charge up the fine particulates. The charged particulates are collected with the oppositely charged collector plates. Electrostatic precipitators are highly efficient in collecting fine particulates. Collected dust is easily handled and disposed of. This is a dry air pollution control process.
Bag Filters
3.18 Bag filters are commonly adopted 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 would be cleaned up regularly to avoid clogging. This is a dry air pollution control process.
Quenching
3.19
If
flue gas is cooled down slowly to about
Flue Gas Cleaning System to be
Adopted in the New Crematorium
3.20 After passing through the heat exchanger, the flue gas will enter the flue gas filtering plant, such that specific pollutants in the gas stream will be trapped. The flue gas filtering plant comprises a cyclone (for separation of large particles and sparks in the flue gas downstream of heat exchanger), a chemical addition system (with calcium hydroxide and furnace coke for neutralizing acidic pollutants such as hydrogen chloride and removing dioxins radicals in flue gas stream), a conditioning rotor (for recycling unused additives) and a flat bag filter (for filtering out fine carbon particulates with compressed air jet).
Clean Fuel
to be Adopted in the New Crematorium
3.21 In order to further reduce emissions of air pollutants from fuel combustion, thereby to be more environmentally-friendly, Towngas has been selected as burning fuel for the new cremators instead of ultra low sulphur diesel (ULSD) which has been using for existing cremators, despite the higher operation cost of using Towngas.
3.22 To further enhance the environmental performance of new cremators against emission of mercury and residual dioxins, chemo-absorption equipment using non-toxic additives is under design and will be added downstream of the flat bed filter, whenever practicable, to ensure compliance with emission limits as stipulated in BPM12/2(06).
Environmental
Legislation, Policies, Plans, Standards and Criteria
3.23
The criteria for evaluating air
quality impacts and the guidelines for air quality assessment are laid down in Annex
4 and Annex 12 of the Technical
3.24 The Air Pollution Control Ordinance (APCO) provides a statutory framework for establishing the Air Quality Objectives (AQOs) and stipulating the anti-pollution requirements for air pollution sources. The AQOs, which must be satisfied, stipulate the maximum allowable concentrations over specific period for a number of criteria pollutants. The relevant AQOs are listed in Table 3.1.
Table 3.1
|
Pollutant |
Maximum
Concentration (mg/m3)(1) |
|||
|
Averaging Time |
||||
|
1 hour(2) |
8 hour(3) |
24 hour(3) |
Annual(4) |
|
|
Total Suspended Particulates (TSP) |
- |
- |
260 |
80 |
|
Respirable Suspended Particulates (RSP) (5) |
- |
- |
180 |
55 |
|
|
800 |
- |
350 |
80 |
|
Nitrogen Dioxide (NO2) |
300 |
- |
150 |
80 |
|
Carbon Monoxide (CO) |
30,000 |
10,000 |
- |
|
|
Photochemical Oxidants (as Ozone, O3)
(6) |
240 |
- |
- |
|
Notes:
(1)
Measured at 298 K and
101.325 kPa.
(2)
Not to be exceeded more
than three times per year.
(3)
Not to be exceeded more
than once per year.
(4)
Arithmetic mean.
(5)
Suspended particulates in
air with a nominal aerodynamic diameter of
(6)
Photochemical oxidants are
determined by measurement of ozone only.
3.25 In the absence of statutory guidelines in HKSAR for non-AQO pollutants, chronic and acute criteria from international organization, including the World Health Organization (WHO), USEPA and California Air Resources Board (CARB), are employed for this Project. The air quality criteria for non-AQO pollutants employed for this Project are shown in Table 3.2.
Table 3.2 Air Quality Criteria for non-AQO Pollutants
|
Pollutant |
Unit |
Criteria |
|
|
Hourly |
Annual |
||
|
Hydrogen Chloride (HCl) |
mg/m3 |
2,100(2) |
20(3) |
|
Mercury (Hg) |
mg/m3 |
0.6(2) |
1.0(4) |
|
Dioxins(1) |
pg
I-TEQ/m3 |
- |
40(5) |
Notes:
(1)
Expressed as chlorinated dioxins and
dibenzofurans
(2)
Reference Exposure Limits, Office of
Environmental Health Hazard Assessment,
(3)
Integrated Risk Information System, USEPA.
(4)
WHO Air Quality Guideline, World Health Organization.
(5)
Chronic reference exposure from California
EPA recommended air quality standard (OEHHA)
3.26
The EIAO-TM stipulates that the
hourly TSP level should not exceed
3.27 Notifiable and regulatory works are under the control of the Air Pollution Control (Construction Dust) Regulation. Notifiable works are site formation, reclamation, demolition, foundation and superstructure construction for buildings and road construction. Regulatory works are building renovation, road opening and resurfacing slope stabilisation, and other activities including stockpiling, dusty material handling, excavation, concrete production etc. This Project is expected to include both notifiable and regulatory works. Contractors and site agents are required to inform the Environmental Protection Department (EPD) on carrying out construction works and to adopt dust reduction measures to reduce dust emission to the acceptable level.
3.28 Any process which is designed as a Specified Process under the APCO, including the re-provisioned Cape Collinson Crematorium, should be conducted with a licence granted by the Direction of Environmental Protection. The process should be carried out with the use of best practicable means to prevent the emissions of noxious and offensive pollutants into the atmosphere.
3.29 The Air Pollution Control Ordinance (APCO) provides a legislation control on the removal of asbestos-containing materials. In accordance with the APCO, the owner of the premises which contain, or are reasonably suspected of containing, asbestos-containing materials should employ a registered asbestos consultant to conduct an asbestos investigation and prepare an Asbestos Investigation Report (AIR). If suspected asbestos-containing material (ACM) is identified, an asbestos abatement plan providing details and specifications of the asbestos removal procedures to control and minimise the release of asbestos fibres from the identified ACM should submit to EPD at least 28 days before the commencement of the asbestos abatement work. Under the APCO, registered asbestos professionals are required to supervise, audit and monitor the asbestos abatement work.
3.30 In the absence of statutory guidelines in HKSAR for cancer risk pollutants, international criteria from WHO, USEPA and CARB are employed for the health risk criteria for this Project. The health risk criteria for cancer risk pollutants are shown in Table 3.3.
Table 3.3 Health Risk Guideline for Exposure to Cancer Risk Pollutants
|
Acceptability of
Cancer Risk |
Estimated
Lifetime Individual Excess Cancer Risk Level(1) |
|
|
Significant |
>
10-4 |
|
|
Risk should be reduced to As Low As
Reasonably Practicable (ALARP) |
>
10-6 to 10-4 |
|
|
Insignificant |
<=
10-6 |
|
Note:
(1)
The estimated lifetime individual excess
cancer risk level is assumed as 70 years as recommended by WHO.
Description of the Environment
Environs
3.31
The proposed site is located at
the existing Cape Collinson Crematorium at
3.32
The proposed site is in a
predominantly rural area with a very low population density. The nearest domestic premises are mainly
located alongside
Background Air Quality
3.33 There is no fixed air quality monitoring station near the proposed site. The nearest EPD air monitoring station is Eastern Air Quality Monitoring Station. In accordance with the EPD’s Guidelines in Assessing the ‘TOTAL’ Air Quality Impacts, the latest five years (Year 2003 – 2007) average monitoring data should be adopted as the background concentration. The background air pollutant concentrations adopted in this study are presented in Table 3.4.
Table 3.4 Background Air Pollutant Concentrations adopted in this Study
|
Pollutant |
Background
Concentration (mg/m3) |
|
Total Suspended Particulates (TSP) |
78
(1) |
|
Respirable Suspended Particulates (RSP) |
50 |
|
|
16 |
|
Nitrogen Dioxide (NO2) |
57 |
|
Carbon Monoxide (CO) |
799 (2) |
|
Photochemical Oxidants (as Ozone, O3) |
63 (3) |
|
Mercury (Hg) |
0.0002 (4) |
|
Dioxins (pg I-TEQ/m3) |
0.071 (5) |
Notes:
(1)
In absence of the TSP concentration recorded
at EPD’s Eastern Air Quality Monitoring Station, the
five years (Year 2003 – 2007) average monitoring data
recorded at Central/Western Air Quality Monitoring Station is adopted.
(2)
There is no monitoring data
of CO from Eastern Station, the average value from other non-roadside
monitoring stations including Tsuen Wan, Tung Chung, Yuen Long and Tap Mun are adopted.
(3)
The O3
concentration is 5-year average of the annual average of daily hourly maximum
concentration recorded at Eastern Air Quality Monitoring Station in Year 2003 - 2007.
(4)
Air quality monitoring data
from Air Quality in
(5)
There are only two
monitoring stations for toxic air pollutants monitoring, i.e. Central/Western
station and Tsuen Wan station. The
5-years (Year 2003 – 2007) average monitoring data
recorded at the nearest Air Quality Monitoring Station, Central/Western is
adopted.
3.34 In accordance with Annex 12 of the EIAO-TM, any domestic premises, hotel, hostel, hospital, clinic, nursery, temporary housing accommodation, school, educational institution, office, factory, shop, shopping centre, place of public worship, library, court of law, sports stadium or performing arts centre are considered as air sensitive receivers (ASRs).
3.35
As stated in the EIA study brief, the boundary of the
assessment area for air quality assessment should be
3.36
The air quality impact at
Table 3.5 Identified Air Sensitive Receivers
|
ASR |
Description |
Land Use |
Horizontal
Separation from the Chimney (m) |
Assessment
Height (metre above ground) |
Assessment
Height (mPD) |
|
A1 |
Staff
Quarters of |
Residential |
130 |
1.5
& 4.5 |
158.2
& 161.2 |
|
A2 |
Staff
Quarters of Tai Tam Gap Correctional Institution |
Residential |
180 |
1.5,
4.5, 7.5 & 10.5 |
157.5,
160.5, 163.5 & 166.5 |
|
A3 |
Staff
Quarters of |
Residential |
255 |
1.5
& 4.5 |
140.1
& 143.1 |
|
A4 |
Sai
Wan |
Office |
345 |
1.5 |
106.4 |
|
A5 |
|
Religionary |
260 |
1.5 |
67.3 |
|
A6 |
|
Residential |
185 |
1.5,
5, 10, 20, 40, 60, 80, 85, 90, 95 & 98 |
65.9,
69.4, 74.4, 84.4, 104.4, 124.4, 144.4, 149.4, 154.4, 159.4 & 162.4 |
|
A7 |
Staff
Quarters of Water Supplies Department |
Residential |
350 |
1.5
& 4.5 |
108.9
& 111.9 |
|
A8 |
|
Residential |
290 |
1.5,
5, 10, 20, 40, 60, 80, 85, 90, 95 & 98 |
61.5,
65, 70, 80, 100, 120, 140, 145, 150, 155 & 158 |
|
A9 |
Hiu
Fung House, Fung Wah Estate |
Residential |
230 |
1.5,
5, 10, 20, 40, 60, 80, 85, 90, 95 & 98 |
63,
66.5, 71.5, 81.5, 101.5, 121.5, 141.5, 146.5, 151.5, 156.5 & 159.5 |
Identification of Environmental Impacts
Potential Air Quality
Impact
3.37 Major potential air quality impacts arising from the Project would be:
Dust emission from
demolition/construction of the Project;
Operation of the
Project.
3.38
There is no major industrial
emission and other construction activity within
Construction Phase
3.39 The proposed construction and demolition period for the Project would be from July 2010 to December 2014. It will be implemented into two phase, namely Phases 1 and 2. The construction/demolition works programme of the Project is summarized in the Table 3.6.
Table 3.6 Construction/Demolition Works Programme of the Project
|
Duration |
Description |
Construction
Activity |
|
July 2010 – March 2012) |
Phase 1 Provision of four new cremators and
ancillary facilities |
Site formation;
Building works;
Construction of four new
cremators. |
|
March 2012 – December 2014 |
Phase 2 Demolishing of the existing crematorium and
construction of the remaining facilities for the new crematorium |
Demolition of the
existing crematorium;
Site formation;
Construction of the six
new cremators;
Building works for the
remaining facilities. |
3.40 The proposed construction work for the Project was described in Section 2. Potential air quality impacts arising from the construction of the Project would mainly be related to dust nuisance from site clearance, ground excavation, cut and fill operations and construction of the new cremator and other ancillary facilities. In view of the environmental impacts arsing from the pilling activities, non-percussive pilling method which generated lower dust emissions would be adopted. To minimize potential dust emission, construction method resulting in minimum exposed surface is preferable for excavation works. In order to minimize potential dust emission, the demolition works will be carried out using traditional method without blasting. Dust control measures are implemented to minimize the dust impact. The alternative demolition/construction methods has been discussed in Section 2 of this EIA report.
3.41 Concurrent construction activities in the immediate vicinity of the Project are not identified. Cumulative construction dust impact is therefore not anticipated.
Operation Phase
Transitional Phase (T&C Period of Phase 1)
3.42 As advised by the Project Proponent, the existing crematorium would still be operating to serve the public during the T&C period of the new cremators under Phase 1. However, special arrangement would be made to control that only 8 of 12 existing cremators and 2 of 4 new cremators would operate concurrently at any one time (i.e. less than the maximum number of twelve existing cremators allowable to be operated as stated in the current Specified Process License) during T&C period to avoid additional loading of chimney emissions to the environment.
3.43 While the installed capacity of each new cremator under Phase 1 is 145.7kg/hour based on 70 minutes average cycle time, the installed capacities of existing cremators (C1 to C12) based on 150 minutes average cycle time are as follows:
C1
to C10: 100
kg/hour each
C11
(extra large cremator) 132
kg/hour
C12
(Hindu type cremator) 67.2
kg/hour
3.44
The total capacity of the 8
existing cremators (any 7 of C1 to C10 cremators + C11 cremator, being a combination
of the maximum installed capacity) and 2 new cremators during T&C period is
Table 3.7 Comparison of Emission Limits of Various Air Pollutants for Existing and New Cremators
|
Air Pollutant |
Target Emission
Limit for New Cremators (mg/m3) (1)(2) |
Licensed
Emission Limit for Existing Cremators (mg/m3) (1)(2) |
|
|
Particulates (3) |
40 |
100 |
|
|
Gaseous and vaporous organic substances,
expressed as organic carbon (TOC) |
20 |
20 |
|
|
Hydrogen chloride (HCl) |
30 |
100 |
|
|
Carbon monoxide (CO) |
100 |
100 |
|
|
Mercury and its compounds, expressed as
mercury (Hg) |
0.05 |
- |
|
|
Dioxins |
0.1
(4) |
1
(4) |
|
|
Nitrogen oxides (NOX as NO2) |
380(5) |
- |
|
|
Sulphur dioxide (SO2) |
180(5) |
- |
Notes:
(1)
All air pollutant concentrations are expressed at
reference conditions of temperature 273 K, pressure 101.3 kPa, 11% oxygen and
dry gas.
(2)
The emission limits for all pollutants, except Mercury and Dioxins, are
in hourly average. Average time of
mercury and dioxins emissions limit: a minimum of three complete cremation
cycles or the requisite number of complete cremation cycles to cover a minimum
period of six hours, whichever is the longer duration.
(3)
The particulate emission
limit is assumed to be RSP.
(4)
The unit is ng I-TEQ/m3.
(5)
Reference to the Ministry
of Public Safety &
Operation of the
Project (Phase 1 and Phase 2)
3.45 Aerial emissions from the new cremator would be controlled to within the concentration limits stipulated in ‘A Guidance Note on the Best Practicable Means for Incinerators (Crematoria), BPM 12/2(06), EPD, September 2008’. Major criteria air pollutants of concern from the cremation process include respirable suspended particulate, total organic carbon, hydrogen chloride, carbon monoxide, mercury and dioxins.
3.46
The emission limits of the cremator
to be employed in the study had been agreed with EPD (see Appendix
3.2) and are summarized in Table 3.8. The emission
limits for all pollutants, except Mercury and Dioxins, are in hourly
average. As the worst assumption, the
hourly average emission limit was adopted in predicting the daily average RSP
concentrations at the selected receptors.
It was assumed that the size of particulate matter emitted from the
cremator is less than
Table 3.8 Emission Limits of Various Air Pollutants
|
Air Pollutant |
Target Emission
Limit (mg/m3) (1) |
Emission Limits
in Best Practicable Means (mg/m3) (1) (2) |
Overseas
Emission Standards (mg/m3) (2) |
|
|
|
|
|||
|
Particulates (5) |
40 |
40 |
250 |
40 |
|
Gaseous and vaporous organic substances, expressed
as organic carbon (TOC) |
20 |
20 |
226 |
20 |
|
Hydrogen chloride (HCl) |
30 |
30 |
200 |
30 |
|
Carbon monoxide (CO) |
100 |
100 |
150 |
200 |
|
Mercury and its compounds, expressed as
mercury (Hg) |
0.05 |
0.05 |
3 |
0.05 |
|
Dioxins |
0.1
(6) |
0.1
(6) |
- |
0.1
(6) |
|
Nitrogen oxides (NOX as NO2)
(7) |
380 |
- |
500 |
- |
|
|
180 |
- |
- |
- |
Notes:
(1)
All air pollutant concentrations are expressed at reference
conditions of temperature 273 K, pressure 101.3 kPa, 11% oxygen and dry gas.
(2)
The emission limits for all pollutants, except Mercury and Dioxins, are
in hourly average. Average time of mercury
and dioxins emissions limit: a minimum of three complete cremation cycles or
the requisite number of complete cremation cycles to cover a minimum period of
six hours, whichever is the longer duration.
(3)
Reference to Crematorium
Furnace, Environmental Guidelines for Crematoria and Cremators, April 2004,
(4)
Reference to the Process
Guidance Note 5/2(04) – Secretary of State’s Guidance for Crematoria 2004,
Cremation Society of Great Britain.
(5)
The particulate emission
limit is assumed to be RSP.
(6)
The unit is ng I-TEQ/m3.
(7)
Reference to the Ministry
of Public Safety &
3.47 Apart from the incineration emission, odour nuisance generated from the cremation process would not be expected during the operation of the Project. Dead bodies will be delivered to the crematorium and immediately stored in the refrigerated mortuary in order to control the odour. As such, odour nuisance generated from the dead bodies is not expected. Moreover, no odour complaint was received since the operation of the existing cremators. Odour nuisance from the operation of cremators would not be expected.
3.48
3.49 Other emissions including smoke emission from joss paper burning activities may induce an impact to the nearby environment.
3.50
Within
Construction Phase
3.51
Dust
emissions are estimated from a number of construction activities including site
clearance, formation works, excavation works, demolition and handling of dusty
materials.
3.52
As
mentioned in the above section, the proposed
construction and demolition period for the Project would be implemented in
Phases 1 and 2. The potential dust impacts arising from these
two phases construction works would be assessed.
3.53
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
were presented in Section 4. 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.
3.54
The
impact of fugitive dust sources on air quality depends upon the quantity as
well as the drift potential of the dust particles emitted into the
atmosphere. Large dust particles (i.e.
over
3.55
According
to the USEPA AP-42, construction dust particles may be grouped into nine
particle size classes. Their size ranges
are 0 –
3.56
The
prediction of dust emissions was based on typical values and emission factors
from United States Environmental Protection Agency (USEPA) Compilation of Air Pollution
Emission Factors (AP-42), 5th Edition. As it is difficult to obtain the detailed
information for estimation of emission rates of different dusty construction
activities, emission factor for heavy construction as stated in the USEPA
AP-42, which is higher emission rate, was therefore adopted for general
construction activities in the assessment as the worst assumption. The
predicted dust concentrations at the ASRs may be higher than the actual
situation.
3.57
Table 3.9 gives the relevant clauses for
emission factors used in this assessment in AP-42. Detailed calculation of emission rate and the
potential dust emission sources are presented in
Appendix 3.1.
Table 3.9 Emission Factors for Construction Activities and Wind Erosion
|
Construction
Activities |
Emission Rate |
Remark |
|
Site clearance, formation works, excavation
works, demolition and handling of dusty materials (as
heavy construction) |
E = 1.0378E-04 (g/m2/s) |
50% reduction by water
suppression (watering twice a day)
USEPA AP-42 5th
ED., S. |
|
Wind Erosion |
E = 2.6953E-06 (g/m2/s) |
For night time
emission only
USEPA AP-42 5th
ED., S.11.9 Table |
3.58
The
Air Pollution Control (Construction Dust) Regulation specifies that dust
suppression measures such as watering should be applied for the construction
site. With reference to Section
3.59
As
confirmed with the Project Proponent, 12 working hours per day (07:00 – 19:00)
was assumed for the dusty construction works in the assessment.
3.60
Fugitive
Dust Model (FDM) (1993 version) was adopted to assess potential dust impact
from the construction works. The worst
case meteorological data was used to predict the 1-hour and 24-hour average TSP
concentrations at representative discrete ASRs close to the construction
works. Since the construction activities
would be undertaken at ground level and underground level, the worst dust
impact on the ASRs would be at the ground floor of the ASRs. The height of
Wind speed:
Wind direction: 360 wind direction
Stability class: D (daytime) & F (night
time)
Surface roughness:
Mixing height:
3.61
In
accordance with the EPD’s Guideline on Assessing the “Total” Air Quality
Impacts, the surrounding area of proposed project site was classified as
‘rural’ area and ‘rural’ mode was adopted in the dispersion model. The surface roughness was taken as
3.62
Daily
TSP concentrations were calculated as follows:
Daily TSP concentration = (number of
working hour)/24 ´
(1-hour average maximum TSP concentration during working hours) + (number of
non-working hours)/24 ´ (1-hour average maximum TSP concentration during
non-working hours) + Background
3.63
As
mentioned in Section 3.33, the background TSP concentration of 7
Operation Phase
Chimney Emissions
3.64 The air pollutants from the new cremator chimney would not exceed the concentration limits stipulated in ‘A Guidance Note on the Best Practicable Means for Incinerators (Crematoria), BPM 12/2(06), EPD, September 2008’. As the Project is under preliminary design stage, the emission limits for various air pollutants provided in BPM 12/2(06) were adopted in this assessment as a conservative approach.
3.65
As mentioned in Section 3.21,
Towngas has been selected as burning fuel for the new cremators, nitrogen
dioxide is therefore a concerned air pollutant.
3.66
A
total of ten cremators would be provided in the new crematorium. Nine cremators
would be of
3.67
The locations of the chimneys are shown in Figure
2.5 and the design of the chimneys is summarized in Table 3.10.
|
|
No. of chimney |
Diameter of
Chimney |
Exit Velocity |
Discharge Temperature
of Flue Gas at Chimney Exit |
Chimney Height * |
Exhaust
Direction |
|
Chimneys
for |
9
(S1–S7)
(S9–S10) |
|
|
|
in the range of ~ ~ |
Upward |
|
Chimneys
for |
1 (S8) |
|
|
|
~ |
Upward |
Note:
* See Figure 2.5 (Sheet 6 of 6)
for the exact height of each chimney
3.68
The
maximum air pollutant emission rates were calculated based on the target
emission limits as tabulated in Table
3.8 and the flue gas emission rate.
Detailed calculations are presented in Appendix
3.2 and the
maximum emission rates are summarized in Table
3.11.
Table 3.11 Maximum Emission Rates of Various Air Pollutants
|
Air Pollutant |
Target Emission
Limit (mg/m3) (1) |
Maximum Emission
Rates (g/s) |
|
|
|
|
||
|
Particulates (2) |
40 |
1.998E-02 |
2.575E-02 |
|
Gaseous and vaporous organic substances,
expressed as organic carbon |
20 |
9.989E-03 |
1.288E-02 |
|
Hydrogen chloride (HCl) |
30 |
1.498E-02 |
1.931E-02 |
|
Carbon monoxide (CO) |
100 |
4.995E-02 |
6.438E-02 |
|
Mercury and its compounds, expressed as
mercury (Hg) |
0.05 |
2.497E-05 |
3.219E-05 |
|
Dioxins |
0.1
(3) |
4.995E-11 |
6.438E-11 |
|
Nitrogen oxides (NOX as NO2) |
380 |
1.898E-01 |
2.447E-01 |
|
Sulphur dioxide (SO2) |
180 |
8.991E-02 |
1.159E-01 |
Notes:
(1) Emission
limits are reference to 0°C, 101.325 kPa, 11% oxygen and dry
gas.
(2) The
particulate emission limit is assumed to be RSP.
(3) The
unit is ng I-TEQ/m3.
3.69
After
the completion of the Project, the new crematorium will be operated for a
maximum of 17 hours starting at 0930 every day.
Air Dispersion
Model
3.70
An
air dispersion model, Industrial Source Complex Short Term (ISCST3) was used to
simulate the respective dispersion for the potential air quality impacts.
3.71
Hourly meteorological data including wind speed, wind
direction, air temperature, Pasquill stability class and mixing height from the
nearest Hong Kong Observatory weather station, North Point Station, for the
year 2007, was employed for the model run.
3.72
In accordance with the EPD’s Guideline on Assessing
the “Total” Air Quality Impacts, the surrounding area of proposed project site
was classified as ‘rural’ area and ‘rural’ mode was adopted in the dispersion
model.
NO2/NOX
Conversion
3.73
The
NO2/NOX conversion for chimney emissions from the
cremators for all averaging periods was estimated individually based on the
Ozone Limiting Method. The 5-year
average of the annual average of the daily hourly maximum ozone concentrations
recorded at EPD’s Eastern Air Quality Monitoring Station of 63 µg/m3 was
adopted for the calculation. The NO2/NOX
conversion was calculated as follows:
[NO2]pred = 0.1
´ [NOX]pred
+ MIN {0.9 ´ [NOX]pred,
or (46/48) ´ [O3]bkgd}
where
[NO2]pred is the predicted NO2
concentration
[NOX]pred is the predicted NOX
concentration
MIN means
the minimum of the two values within the brackets
[O3]bkgd is the representative O3
background concentration
(46/48) is the molecular weight of NO2 divided by the
molecular weight of O3
Concentration
Calculation
3.74
The
air quality impact at various air pollutants was predicted at the identified
receivers. The background air quality
level, as presented in Table 3.4, was added to predict the cumulative
impact.
Joss Paper Burning
3.75
In
accordance with the latest design of the Project, three units joss paper
burning as shown in Figure 2.5 would
be installed on Level 1 of the re-provisioned crematorium. Assuming 6 cremation time slots are available
a day, the duration of a typical joss burning memorial ceremony is 10 minutes
and the burning material is assumed to be
3.76
In
view of the relatively low level emissions from joss paper burnings, the
impacts was expected to be localized and would not be transported a long
distance in its dispersion. Therefore,
the impact to the nearest ASR, which located about 1
3.77 In order to further reduce nuisance from joss paper burnings, joss paper burners will be incorporated with flue gas treatment system with principle similar to that which was already installed at Diamond Hill Crematorium. Hot dark smoke generated from the joss papers burning is firstly extracted through a U-shaped cooling duct and then a water spraying section for cooling of the smoke, removal of fume and large smoke particles. Fine smoke particles in the pre-treated air stream are then collected by passing through a specially-design electrostatic precipitator. Upon the multi-stage air treatment, the smokeless clean air is discharged via an extraction fan to the atmosphere. Besides, the following administrative mitigation measures would also be adopted:
FEHD will limit
the use of joss paper burners which allows for memorial ceremonies upon request
by the relatives. Other usage of joss
paper burners will not be allowed;
Guidance will be
provided to the users to advise them to minimise the quantity of burning materials;
and
FEHD staff will
advise the users to ensure better combustion of the joss paper in order to
reduce smoke emission.
3.78 With flue gas treatment system incorporated and the implementation of the above mitigation measures, nuisance arising from joss paper burning was anticipated to be negligible.
Health Risk Assessment
3.79 The potential health impact would be expected arising from the operation of the Project. The major toxic air pollutants of concern included dioxins and mercury. Inhalation pathway had been considered as the most significant exposure pathway. The inhalation unit risk factor for dioxins of 38 (mg/m3)-1 recommended by CARB and the highest annual dioxins concentrations at ASRs due to aerial emissions from the new cremators had been adopted to assess the cancer risk of dioxins. The cancer risk from the exposure of dioxins via inhalation was calculated by the following equations:
Cancer Risk = EC ´ URF
where
EC = Exposure dioxin concentration
URF = Unit Risk Factor
3.80 The exposure dioxins concentration would be calculated by the following equations:
EC = (Ca x EF ´ ED) / AT x 365 day/yr
where
EC = Exposure air concentration of
dioxins (mg/m3)
Ca = air concentration
(annual average) of dioxins (mg/m3)
EF = exposure frequency (days/yr)
ED = exposure duration (yr)
AT = averaging time (yr)
3.81 Table 3.12 lists the parameter values to be adopted for calculating the exposure dioxins concentration.
Table 3.12 Value Adopted for Exposure Frequency, Exposure Duration and Average Time
|
Parameter |
Adopted Value |
Unit |
Remarks |
|
Exposure
Frequency |
350
for residents |
days/year |
Adopted
from USEPA, HHRAP, 2005 |
|
Exposure
Duration |
70 |
years |
Design
life of cremator |
|
Average
Time |
70 |
year |
Adopted
from USEPA, HHRAP, 2005 |
Note:
Exposure frequency for off site workers was determined based on number of
working days.
3.82 The inventory for dioxins in g l-TEQ/yr and mercury in g/yr had been estimated based on the emission concentration and annual volumetric flow.
Prediction and Evaluation of Environmental Impacts
Construction Phase
Fugitive Dust Emissions from Phase 1 and
Phase 2 Works
3.83 The potential dust impacts arising from demolition and construction of the Project were assessed and their maximum hourly and daily average TSP concentrations at representative ASRs during construction phase (Phase 1 and Phase 2) are summarized in Table 3.13.
Table 3.13 Predicted Hourly and Daily Average TSP Concentrations During Construction Phase
|
ASR |
Assessment
Height (metre above ground) |
Predicted TSP
Concentration in mg/m3 (Phase 1) |
Predicted TSP
Concentration in mg/m3 (Phase 2) |
||
|
Hourly Average |
Daily Average |
Hourly Average |
Daily Average |
||
|
A1 |
1.5 |
142
|
112
|
207
|
146
|
|
|
4.5 |
140
|
111
|
201
|
142
|
|
A2 |
1.5 |
116
|
98
|
149
|
116
|
|
|
4.5 |
116
|
98
|
149
|
116
|
|
|
7.5 |
113
|
96
|
142
|
112
|
|
|
10.5 |
108
|
94
|
134
|
107
|
|
A3 |
1.5 |
101
|
91
|
119
|
100
|
|
|
4.5 |
102
|
91
|
120
|
101
|
|
A4 |
1.5 |
93
|
86
|
103
|
92
|
|
A5 |
1.5 |
103
|
92
|
117
|
99
|
|
A6 |
1.5 |
135
|
108
|
164
|
124
|
|
|
5 |
133
|
107
|
162
|
122
|
|
|
10 |
120
|
99
|
144
|
112
|
|
|
20 |
94
|
86
|
106
|
92
|
|
A7 |
1.5 |
97
|
88
|
116
|
99
|
|
|
4.5 |
98
|
89
|
117
|
99
|
|
A8 |
1.5 |
101
|
91
|
115
|
98
|
|
|
5 |
102
|
91
|
116
|
98
|
|
|
10 |
99
|
89
|
112
|
96
|
|
|
20 |
91
|
85
|
101
|
89
|
|
A9 |
1.5 |
114
|
97
|
133
|
107
|
|
|
5 |
113
|
97
|
133
|
107
|
|
|
10 |
108
|
93
|
125
|
102
|
|
|
20 |
94
|
86
|
105
|
92
|
Note: Background concentration of 7
3.84
The above results indicated
that the predicted TSP concentrations at the identified representative ASRs
during Phase 1 and Phase 2 construction would comply with and far below the
respective criteria of
Fugitive Emissions of Dioxin Contaminated Dust from Demolition of
Existing Crematorium
3.85 The existing crematorium has been operated for more than 40 years. The interior surface of the chimney, flue gas ducting and combustion chambers may be contaminated with dioxins. Demolition of the existing crematorium may generate fugitive emissions of toxic air pollutants to the atmosphere. Since the existing crematorium is still in operation, it is not feasible to collect samples of surface deposition to verify whether the interior surface of the chimney is contaminated with toxic air pollutants.
3.86 A confirmatory test of dioxins in the depositions on chimney wall, flue gas ducting and combustion chambers will be carried out after decommissioning and prior to the demolition of the existing crematorium. Classification of contamination levels of the contaminated materials inside chimney, flue gas ducting and combustion chambers and the proposed mitigation measures for handling, transportation, treatment and disposal are described in Section 4. As the demolition waste will be properly handled to avoid potential fugitive emission of dioxins, according to the waste management practices as detailed in Section 4, no adverse air quality impact from the fugitive emission of contaminated dust during demolition of the existing crematorium would be expected.
Demolition and Removal of Asbestos Containing Material (ACM)
3.87 An asbestos investigation for the existing crematorium was conducted to identify the extent of the ACM existing in the building before any further demolition work to be commenced. The Asbestos Investigation Report (AIR) for the existing crematorium is presented in Appendix 3.3.
3.88 The investigation was carried out at the external structure of the crematorium main building and cremator at Hindu Service Hall. All the consealed pipelines inside the wall, most of the flange connection covered by metal cover, interior lining of the chimney stack and cremators no. 1 – 11 were not inspected since the crematorium was still in operation.
3.89 Refer to the findings of the AIR, it was indicated that no ACM was found in the six columbarium blocks and car park area. Although ACM were detected in the insulation sheet outside the cremation room and flue gasket at roof of cremator no. 11, the ACM was identified as low friability nature and good condition. Health hazard was therefore expected to be relatively low, and would not impose health hazard to the occupier. The Asbestos Abatement Plan (AAP) is also presented in Appendix 3.3.
3.90 As some areas were inaccessible for carrying out asbestos investigation at this stage, the project proponent shall hire a Registered Asbestos Consultant to investigate and submit to EPD a full AIR and AAP in accordance with the APCO requirements after decommissioning and prior to demolition of the existing crematorium. The report would address the work method of removing ACM contaminated with dioxin containing material (DCM) in the areas of cremators, exhaust ducts or chimney and flue lagging as well as the asbestos waste disposal contaminated with DCM.
3.91 In accordance with the APCO, the following precautionary and mitigation measures would be taken during removal of ACM:
enclosure of the
work area;
containment and
sealing for the asbestos containing waste;
provision of
personal decontamination facilities;
use of personal decontamination
facilities;
use of personal
respiratory/protection equipment;
use of vacuum
cleaner fitted with a high efficiency particulate air filter for cleaning up
the works area; and
carrying out air
quality monitoring during the asbestos abatement works.
3.92 In addition, APCO also requires the appointment of qualified personnel to carry out the asbestos abatement works:
a registered
asbestos contractor shall be employed to carry out the removal and disposal
works for the identified ACM;
a licensed asbestos
waste collector shall be appointed to collect and dispose of the asbestos
waste;
a registered
asbestos laboratory shall be engaged to conduct air monitoring in the course of
asbestos abatement work;
an on-site
registered asbestos supervisor shall be present during the carrying out of the
abatement work to supervise the abatement work;
a registered
asbestos consultant shall be employed to supervise and certify the asbestos
abatement work.
3.93 With the implementation of the above precaution and mitigation measures, the impact of asbestos exposure due to the decommissioning of the existing crematorium would be expected to be insignificant.
Site Management for Handling Asbestos Containing Materials
3.94 The asbestos materials in each building/premise must be abated before other contractors/trades are allowed to work in the building/premises.
3.95 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 valuable items such as electrical cable and copper pipes. Besides, it is recommended that priority shall be given for the abatement of all friable ACM.
3.96 As different contractors may be working on-site at the same time, the following measures shall be considered:
If there is a
sensitive receptor around the area, conduct air monitoring at this off-site
receptor; and
Submit to EPD a completion
report including photos and air monitoring results, immediately after
completion of asbestos work for every work zone.
Operation Phase
Chimney Emissions
3.97
The air quality impacts at the
representative ASRs within study area of
3.98
The air quality assessment
results presented in Appendix 3.4
indicated that the predicted air pollutant concentrations at all representative
ASRs would comply with the respective criteria.
The first and second highest pollutant concentrations would occur at A1
at
Table 3.14 Predicted Highest Concentration of Various Air Pollutants at ASRs
|
Air Pollutant |
Predicted
Highest Concentration (mg/m3) |
|||
|
Hourly Average |
8-Hour Average |
Daily Average |
Annual |
|
|
RSP |
- |
- |
59 |
50 |
|
TOC |
32 |
- |
4 |
- |
|
HCl |
49 |
- |
- |
0.3 |
|
CO |
961 |
858 |
- |
- |
|
Hg |
0.081 |
- |
- |
0.0006 |
|
Dioxins |
- |
- |
- |
0.0718
pg l-TEQ |
|
NO2 |
179 |
- |
126 |
60 |
|
SO2 |
308 |
- |
55 |
18 |
Note: Background concentrations are included.
Health Risk Assessment
3.99 As shown in Table 3.14, the highest annual average dioxins concentration was 8.38 ´ 10-4 pg l-TEQ (without background dioxin concentration of 0.071 pg l-TEQ), the cancer risk was estimated to be 3.05 ´ 10-8, which is lower than the insignificant risk level of 1´10-6. Therefore, the cancer risk due arising from the operation of the Project would be insignificant at all ASRs.
3.100 The inventory of dioxins and mercury were estimated based on the emission concentration and annual volumetric flow.
3.101
The annual volumetric flow rate of the Project was estimated to be
Mitigation of Adverse Environmental Impacts
Construction Phase
3.102 To ensure compliance with the relevant standards, dust mitigation measures stipulated in the Air Pollution Control (Construction Dust) Regulation and good site practices should be incorporated in the contract document to control potential dust emission from the site. The major dust suppression measures include:
skip hoist for
material transport should be totally enclosed by impervious sheeting;
every vehicle should
be washed to remove any dusty materials from its body and wheels before leaving
a construction site;
the area where
vehicle washing takes place and the section of the road between the washing
facilities and the exit point should be paved with concrete, bituminous
materials or hardcores;
where a site
boundary adjoins a road, streets or other accessible to the public, hoarding of
not less than
every stack of
more than 20 bags of cement should be covered entirely by impervious sheeting
places in an area sheltered on the top and the 3 sides;
all dusty
materials should be sprayed with water prior to any loading, unloading or
transfer operation so as to maintain the dusty materials wet;
the excavation
area should be limited to as small in size as possible and backfilled with
clean and/or treated soil shortly after excavation work;
the height from
which excavated materials are dropped should be controlled to a minimum
practical height to limit fugitive dust generation from unloading;
the load of dusty
materials carried by vehicle leaving a construction site should be covered
entirely by clean impervious sheeting to ensure dust materials do not leak from
the vehicle; and
instigation of an
environmental monitoring and auditing program to monitor the construction
process in order to enforce controls and modify method of works if dusty
conditions arise.
Operation Phase
3.103
Air pollution control and stack
monitoring system will be installed for the Cape Collinson Crematorium to
ensure that the emissions from the cremator stacks will meet the target
emission limits equivalent to those stipulated in
Evaluation of Residual Impacts
Construction Phase
3.104 With the implementation of dust suppression measures stipulated in Air Pollution Control (Construction Dust) Regulation during construction, no adverse residual dust impact would be expected.
Operation Phase
3.105 The design and emission concentration limits of the new cremators would comply with the BPM 12/2(06) and target emission limit requirements. The predicted air quality impacts on all the ASRs satisfy all the relevant limits and guidelines, and therefore no adverse residual impact from chimney emission and odour emission would be expected.
Environmental Monitoring and Audit
Construction Phase
3.106 With the implementation of the proposed dust suppression measures, good site practices and dust monitoring and audit programme, acceptable dust impact would be expected at the ASRs. For regular impact monitoring, the sampling frequency of at least once in every six-days, shall be strictly observed at all the monitoring stations for 24-hour TSP monitoring. For 1-hour TSP monitoring, the sampling frequency of a least three times in every six-days should be undertaken when the highest dust impact occurs. Details of the monitoring requirements such as monitoring locations, frequency of baseline and impact monitoring are presented in the stand-alone EM&A Manual.
Operation Phase
3.107
During operation of the new
crematorium, the air pollutants of concern include respirable suspended
particulate, total organic carbon, hydrogen chloride, carbon monoxide, mercury,
dioxins, sulphur dioxide and nitrogen dioxide.
The predicted air quality at the nearby ASRs would comply with the AQOs
and relevant air quality guidelines with the implementation of recommended
mitigation measures. No odour nuisance
from the new crematorium is anticipated.
By incorporating flue gas treatment system in joss paper burners and
limiting joss paper burning activities through administration procedures,
nuisance arising from joss paper burning is anticipated to be negligible.
3.108 In order to ensure compliance with the legislation requirements, the conditions and the continuous monitoring stipulated in the BPM12/2(06) – A Guidance Note on the Best Practicable Means for Incinerators (Crematoria), published by EPD, shall be conducted. The monitoring of the air pollutants shall comply with the requirements of BPM and future Specified Process License of new crematorium, to be issued by EPD under the APCO. Necessary monitoring equipment and techniques should be provided and used to demonstrate that the process is properly operated and the emissions can be minimized to meet the air pollution control requirements. The scope, manner and frequency of the monitoring should be sufficient for this purpose and will be determined by EPD.
3.109 The potential dust impacts arising from the demolition and construction of the Project were assessed. Results showed that the predicted air quality at the ASRs would comply with and far below the respective criteria with the implementation of dust suppression measures as stipulated in the Air Pollution Control (Construction Dust) Regulation. Air monitoring and audit programme is proposed to ensure proper implementation of mitigation measures.
3.110 No adverse air quality impact would be expected during operation of the new cremators. Nevertheless, in order to ensure compliance with the legislation requirements, the conditions and the continuous monitoring stipulated in the BPM12/2(06) shall be conducted.