Environmental Impact Assessment Ordinance (Cap. 499)
Section 5 (7)
Environmental Impact Assessment Study Brief No. ESB-084/2001
Project Title: Cement Silos Addition Work in Tai Po Cement Depot
Name of Applicant: K. Wah Materials Ltd.
1.1 An application (No. ESB-084/2001) for an EIA Study Brief under section 5(1) of the EIAO was submitted by the Applicant on 18 September 2001 with a project profile (No. PP-143/2001).
1.2 In the project profile the proponent proposed to build three additional cement silos of total capacity at 7,500 MT for storage of cement, within the existing Cement Depot (consists of 6 cement silos of total capacity at 8,500 MT). The total capacity of the new Cement Depot will be 16,000 MT. The construction of the three cement silos with associated facilities and the operation of the Cement Depot are hereinafter referred to as "the Project". The location and the boundary of the Cement Depot is shown in Appendix A attached to this study brief.
1.3 Pursuant to section 5(7)(a) of the EIA Ordinance, the Director of Environmental Protection (the Director) issues this Environmental Impact Assessment (EIA) study brief to the Applicant to carry out an EIA study.
1.4 The purpose of this EIA study is to provide information on the nature and extent of environmental impacts arising from the construction and operation of the Designated Project as describe in section 1.2 above and related activities taking place concurrently. This information will contribute to decisions by the Director on:
(i) the overall acceptability of any adverse environmental consequences that are likely to arise from the construction of the additional cement silos and the operation of the Project;
(ii) the conditions and requirements for the detailed design, construction and the operation of the Project to mitigate against adverse environmental consequences wherever practicable; and
(iii) the acceptability of residual impacts after the proposed mitigation measures are implemented.
2. OBJECTIVES OF THE EIA STUDY
2.1 The objectives of the EIA study are as follows:
(i) to describe the Project and the associated works together with the requirements for carrying out the Project;
(ii) to give an account of the considerations(s) given to different alternatives including alternative locations of the additional cement silos with a view to avoiding and minimizing the potential environmental impacts to the sensitive uses;
(iii) to identify and describe the elements of the community and environment likely to be affected by the Project;
(iv) to identify and quantify emission sources and determine the significance of impacts on sensitive receivers and potential affected uses;
(v) to identify any potential visual impacts and to propose measures to mitigate these impacts;
(vi) to propose the provision of infrastructure or mitigation measures so as to minimize pollution, environmental disturbance and nuisance arising from the Project;
(vii) to identify, predict and evaluate the residual environmental impacts (i.e. after practicable mitigation) and the cumulative effects expected to arise from the construction and the operation of the Project in relation to the sensitive receivers and potential affected uses;
(viii) to identify, assess and specify methods, measures and standards, to be included in the detailed design, construction and operation of the Project, which are necessary to mitigate these environmental impacts and reducing them to acceptable levels;
(ix) to investigate the extent of side-effects of proposed mitigation measures that may lead to other forms of impacts and to identify the constraints associated with the mitigation measures; and
(x) to identify, design and specify the environmental monitoring and audit requirements, to ensure the implementation and the effectiveness of the environmental protection and pollution control measures adopted.
3. DETAILED REQUIREMENTS OF THE EIA STUDY
3.1 The Purpose
The purpose of this study brief is to scope the key issues for the EIA study. The Applicant has to demonstrate in the EIA report that the criteria in the relevant sections of the Technical Memorandum on the Environmental Impact Assessment Ordinance (hereinafter referred to as the Technical Memorandum "TM") and the requirements specified below are fully complied with.
3.2 The Scope
3.2.1 The EIA study shall cover the Project scope mentioned in section 1.2 above. In the EIA study, the Applicant shall describe in detail the nature, scope and extent of the Project, covering all phases and key sequences of the Project. The EIA report shall contain a development programme for the Project indicating the duration of the construction and operational phases.
3.2.2 The Applicant shall state clearly in the EIA report the purpose of the Project, in particular the problem(s) or opportunity(s) that the Project is intended to solve or satisfy, and what is to be achieved by carrying out the Project.
3.2.3 The EIA study shall address the likely key issues described below, together with any other key issues identified during the course of the EIA study.
(i) To explore and present the considerations given to different alternatives, including alternative locations of the additional cement silos, with a view to avoiding and minimizing the potential environmental impacts to the sensitive residential complex (Casa Marina III) and other sensitive uses;
(ii) To assess the dust impact and cumulative dust impacts due to the construction and operation of the Project;
(iii) To assess the construction noise, fixed noise source and traffic noise impacts and cumulative noise impacts due to the construction and operation of the Project;
(iv) To assess the landscape and visual impacts due to the construction and operation of the Project; and
(v) To assess the water quality impact and cumulative water quality impacts due to the construction and operation of the Project.
3.3 Consideration of Alternatives
3.3.1 When preparing the EIA report in accordance with the technical requirements below and the TM, the applicant shall indicate in the EIA report the considerations given to different alternatives regarding project siting, design, construction, and operation etc., with an aim to avoiding or minimizing the potential environmental impacts of the Project. The Applicant shall objectively compare the environmental benefits and dis-benefits of the different alternatives, set out the reasons for selecting the final preferred option, and adequately describe the part of environmental factors played in the selection.
3.4 Technical Requirements
The Applicant shall conduct the EIA study to address all environmental aspects of the activities as described in the scope as set out under paragraph 3.2 above. The EIA study shall include the following technical requirements on specific impacts:
3.4.1 Air Quality Impact
184.108.40.206 The Applicant shall follow the criteria and guidelines for evaluating and assessing air quality impact as stated in section 1 of Annex 4 and Annex 12 of the TM respectively. The assessment shall be based on the best available information at the time of the assessment.
220.127.116.11 The assessment area for air quality impact shall generally be defined by a distance of 500m from the boundary of the Project site and as well as along the major transportation routes to be used by the Project for its operation, yet it may be extended depending on the circumstances and the scale of the project. For this Project, the assessment shall include but not to be limited to the existing, planned and committed Sensitive Receivers near by the Cement Depot (e.g Casa Marina III, Fortune garden, Tycoon Place, Village Houses, Sha Lan Villa, Wu York Yu Care and Attention Home, Ship Yard, Tai Po Marine Office, Wholesale Fish Market, etc..), around the anchorage of ocean going vessels where cement transferring into barges are carried out (e.g. Bayshore Tower, Villa Oceana, Fok On Garden, Chung On Estate, etc..) and along the major route of the transportation route (e.g. along Ting Kok Road etc..) usually used by the cement tankers/heavy vehicles.
18.104.22.168 The Applicant shall assess the air pollutant concentrations with reference to the relevant sections of the guidelines in Appendices B-1 to B-3 attached to this study brief, or other methodology as agreed by the Director. The Applicant shall follow the criteria and guidelines for evaluating and assessing air quality impact as stated in Annexes 4 and 12 of the TM, respectively.
22.214.171.124 The air quality impact assessment shall include the following:
Background and analysis of activities
a) Provide background information relating to air quality issues relevant to the project, e.g. description of the types of activities during construction and operation stages of the project that will likely give rise to dust emissions.
b) Give an account, where appropriate, of the consideration/measures that had been taken into consideration in the planning of the project to abate the air pollution impact. That is, the Applicant should consider alternative construction methods/phasing programmes and alternative modes of operation to minimise the constructional and operational air quality impact respectively. Examples include the use of marine access routes for transportation of construction materials to avoid dust impact on ASRs due to haul road transport during construction. During the operational stage the applicant shall follow the requirements as stipulated in Best Practicable Means (BPM 3/1) for Cement Works (Cement Depot) attached as Appendix 4 of this study brief, in dust control and in conjunction with any additional mitigation measures to ensure operational dust impacts are controlled within the relevant standard as stipulated in Annex 4 of the TM.
c) Present the background air quality levels in the assessment area for the purpose of evaluating the cumulative constructional and operational air quality impacts.
Identification of ASRs and examination of emission/dispersion characteristics
d) Identify and describe representative existing and planned/committed air sensitive receivers (ASRs) that would likely be affected by the project, including those earmarked on the relevant Outline Zoning Plans, Development Permission Area Plans, Outline Development Plans and Layout Plans. The Applicant shall select the assessment points of the identified ASRs such that they represent the worst impact point of these ASRs. A map showing the location and a description including the name of the buildings, their uses and height of the selected assessment points shall be given. The separation distances of these ASRs from the nearest emission sources should also be given. The Applicant should consider the combined impacts from the construction of additional silos and from the operation of the existing cement depot and review the construction programme, if necessary, in order to minimize the cumulative impact on the ASRs.
e) Describe any topographical and man-made features that may affect the dispersion characteristics of the area of the Project.
f) Provide an exhaustive list of air pollutant emission sources, including any nearby emission sources which are likely to have impact on the project based on the analysis of the constructional and operational activities of the project in (a)above. Examples of constructional stage emission sources include stock piling, drilling/boring, erecting, concrete batching and vehicular movements on unpaved haul roads on site, etc. Examples of operational stage emission sources include handling of bulky and dusty materials, movement of barges, loading and unloading activities and vehicular flow, etc. Confirmation of the validity of the assumptions and the magnitude of the activities (e.g. volume of construction materials handled, traffic mix and volume on a road etc.) shall be obtained from the relevant government department/authorities and documented.
Construction air quality impact
g) The Applicant shall follow the requirements of the Air Pollution Control (Construction Dust) Regulation in dust control to ensure construction dust impacts are controlled within the relevant standards as stipulated in section 1 of Annex 4 of the TM. He shall also initiate an audit and monitoring program during constructional stage to verify the effectiveness of the control measures and to ensure that the construction dust levels be brought under proper control when such program is identified to be necessary.
h) If the Applicant anticipates a significant construction dust impact that will likely cause exceedance of the recommended limits in the TM at the ASRs despite incorporation of the dust control measures stated in (g) above, a quantitative assessment should be carried out to evaluate the construction dust impact at the identified ASRs based on the emission strength of the emission sources identified in (f) above. The Applicant shall follow (l) to (p) below when carrying out the quantitative assessment.
Operational air quality impact
i) The Applicant shall calculate the expected air pollutant concentrations at the identified ASRs. Calculations for the expected impact shall be based on an assumed reasonably worst case scenario under normal operating conditions. The evaluation shall be based on the strength of the emission sources identified in (f) above. The Applicant shall follow (k) to (n) below when carrying out the quantitative assessment.
j) For calculation of future road traffic air pollution impact, this shall be based on the highest emission strength from the road within the next 15 years upon commencement of operation of the proposed road. The Applicant shall demonstrate that the selected year of assessment represents the highest emission scenario given the combination of vehicular emission factors and traffic flow for the selected year.
Quantitative Assessment Methodology
k) The Applicant shall apply the general principles enunciated in the modelling guidelines (paragraph 126.96.36.199 above) while making allowance for the specific characteristic of each project. This specific methodology must be documented in such level of details (preferably with tables and diagrams) to allow the readers of the assessment report to grasp how the model is set up to simulate the situation at hand without referring to the model input files. Details of the calculation of the emission rates of air pollutants and a map showing all the road links for input to the modelling shall be presented in the report. The Applicant must ensure consistency between the text description and the model files at every stage of submission. In case of doubt, prior agreement between the Applicant and the EPD on the specific modelling details is advised.
l) The Applicant shall, based on the nature of the activities, analysed in (f) above, identify the key/representative air pollutant parameters (types of pollutants and the averaging time concentration) to be evaluated and provide explanation for choosing these parameters for the assessment of the impact of the project.
m) The Applicant shall calculate the expected cumulative air pollutant concentrations at the identified ASRs and compare these results against the criteria set out in section 1 of Annex 4 in the TM. The predicted air quality impacts (both unmitigated and mitigated) shall be presented in the form of summary table and pollution contours, for comparison with relevant air quality standards and examination of the land use implications of these impacts. Plans of suitable scale should be used for presentation of pollution contour to allow proper determination of buffer distances requirements.
Mitigation measures for non-compliance
n) The Applicant shall propose remedies and mitigating measures where the predicted air quality impact exceeds the criteria set in section 1 of Annex 4 in the TM. These measures and any constraints on future land use planning shall be agreed with the relevant government departments/authorities and documented. The Applicant shall demonstrate quantitatively that the resultant impacts after incorporation of the proposed mitigating measures will comply with the criteria stipulated in section 1 of Annex 4 in the TM.
Submission of model files
o) All input and output file(s) of the model run(s) shall be submitted to the EPD in electronic format.
3.4.2 Noise Impact
188.8.131.52 The Applicant shall follow the criteria and guidelines for evaluating and assessing noise impact as stated in Annexes 5 and 13 of the TM, respectively.
184.108.40.206 The construction noise impact assessments shall cover the noise generated from the construction activities of the additional cement silos and its associated equipment/facilities combined with the operation noises such as handling and storage activities, loading and unloading activities, movements of the transportation vehicles and operation of barges, etc..
220.127.116.11 The operation noise impact assessments shall cover the noise generated from the Project including the operation noises such as handling and storage activities, on-site and off-site loading and unloading activities, on-site and off-site movements of the transportation vehicles and barges, loading and unloading activities from the ocean going vessels into the cement barges, etc. The assessment shall include the following:
(i) Determination of Assessment Area
The assessment areas shall include all areas within 300m from the proposed boundary of the Project and as well as along the major transportation routes to be used by the Project for its operation, yet it may be extended depending on the circumstances and the scale of the project. For this Project, the assessment shall include but shall not be limited to the existing, planned and committed Sensitive Receivers near by the Cement Depot (e.g. Casa Marina III, Fortune Garden, Tycoon Place, Village Houses, Sha Lan Villa, Wu York Yu Care and Attention Home etc.), within 300m around the anchorage of ocean going vessels where cement transferring into barges are carried out (e.g. Bayshore Tower, Villa Oceana, Fok On GardenChung On Estate, etc..) and along the major route of the transportation route (e.g. along Ting Kok Road etc..) usually used by the cement tankers/heavy vehicles. Subject to the agreement of the Director, the assessment area could be reduced accordingly if the first layer of noise sensitive receivers, closer than 300m from the proposed works boundary of the project, provides acoustic shielding to those receivers located further away.
(ii) Provision of Background Information
The Applicant shall provide all background information relevant to the Project. Background noise levels will be required for assessment of fixed or other noise sources, for which the planning standards involve background noise levels.
(iii) Identification of Noise Sensitive Receivers(a) The Applicant shall refer to Annex 13 of the TM and the approved EIA report when identifying the noise sensitive receivers (NSRs). The NSRs shall include all existing and all planned/committed noise sensitive developments and uses earmarked on the relevant Outline Zoning Plans, Outline Development Plans and Layout Plans, where applicable.
(b) The Applicant shall select assessment points to represent all identified NSRs, for carrying out the quantitative noise assessment described below. The assessment points shall be agreed with the Director prior to the quantitative noise assessment. A map showing the location and description including name of building, use, and floors of each and every selected assessment point shall be given.
(iv) Provision of an Emission Inventory of the Noise Sources
The Applicant shall provide an inventory of noise sources from the Project and the construction equipment for other concurrent activities within the boundary of the Assessment Area.
(v) Noise Assessment(a) The Applicant shall carry out assessment of cumulative noise impact from the Project during day-time, i.e. 7 a.m. to 7 p.m., on weekdays other than general holidays in accordance with the methodology stipulated in paragraphs 5.3. and 5.4 of Annex 13 of the TM. The assessment shall identify the worst-case scenario for the period of the Project. The criteria in Table 1B of Annex 5 of the TM shall be adopted in the assessment.
(b) If the unmitigated noise levels are found to exceed the relevant criteria, the Applicant shall propose practicable direct mitigation measures (including movable barriers, enclosures, quieter alternative methods, re-scheduling and restricting hours of operation of noisy tasks) to minimize the impact. If the mitigated noise levels still exceed the relevant criteria, the duration of the noise exceedance shall be given.
3.4.3 Water Quality Impact
18.104.22.168 The Applicant shall follow the criteria and guidelines for evaluating and assessing water pollution as stated in Annexes 6 and 14 of the TM, respectively.
22.214.171.124 The Applicant shall list out the water bodies, watercourses and streams, which will be affected by the Project together with their beneficial uses and their existing water quality.
126.96.36.199 The Applicant shall identify those activities likely to have an impact on the watercourses, water bodies, and streams. Such activities would include site preparation, construction, operation and maintenance of the Project, removal of spoils and other activities. Possible impacts arising from such activities include changes in hydrology, flow regime, sediment erosion or deposition, water and sediment quality and the effects on the aquatic organisms due to such changes.
188.8.131.52 The Applicant shall evaluate the adverse effects of the Project on the identified water bodies, watercourses and streams. All wastewater generated shall have to meet the TM standards prior to discharge.
184.108.40.206 The Applicant shall evaluate potential storm water run-off and non-point source pollution impacts from the Project and investigate the opportunity of implementing additional storm water Best Management Practices. Pollution control and mitigating measures shall be recommended to reduce those potential impacts to within established standards, objectives and criteria. Attention shall be drawn to the water quality control and mitigation measures recommended in the ProPECC Note on construction site drainage. Where appropriate, the Project should be configured and programmed as to avoid disturbance to or alteration of flow regime of natural stream course as far as practicable.
220.127.116.11 The Applicant shall recommend compliance monitoring programme to monitor the impact to be caused by the operation and maintenance of the Project.
18.104.22.168 The Applicant shall evaluate the residual impacts on the water system(s) and the sensitive receivers with regard to the appropriate water and sediment quality objectives, criteria, standard and guidelines.
3.4.4 Visual Impact
22.214.171.124 The Applicant shall follow the criteria and guidelines as stated in Annexes 10 and 18 of the TM respectively for evaluating and assessing visual impacts. The assessment shall cover the construction, operation and maintenance periods of the Project.
126.96.36.199 The Applicant shall assess the visual impact of the Project. The assessment shall include the following:
(i) identification and plotting of visibility contours of the Project within the assessment area;
(ii) identification of the key groups of sensitive receivers within the visibility contours with regard to views from ground, and inclined levels;
(iii) description of the visual compatibility of the Project with the surrounding and the planned setting, and its obstruction and interference with key views of the adjacent areas; and
(iv) the severity of visual impacts in terms of distance, nature and number of sensitive receivers shall be identified. The visual impacts of the Project with and without mitigation measures shall be included so as to demonstrate the effectiveness of the proposed mitigation measures.
188.8.131.52 Alternative design and options that would avoid or reduce the identified visual impacts shall be evaluated for comparison before adopting other mitigation or compensatory measures to alleviate the impacts. The Applicant shall recommend mitigation measures to minimize the adverse effects as identified in 184.108.40.206 above, including design of structures, provision of finishes to structure, colour scheme and texture of material used, and any other possible measures. Parties shall be identified for the management and maintenance of any proposed mitigation measures to ensure their effectiveness throughout the operation of the Project.
220.127.116.11 Coloured perspective drawings, plans and section/elevation diagrams, annotated oblique aerial photographs, photographs taken at vantage points, photo-retouching and photomontage shall be adopted to illustrate the visual impact of the Project. The Applicant shall record the technical details in preparing the illustration, which may need to be submitted for verification of the accuracy of the illustration.
4. ENVIRONMENTAL MONITORING & AUDIT (EM&A) REQUIREMENTS
4.1 The Applicant shall justify the need for the Environmental Monitoring and Audit (EM&A).
4.2 Subject to the confirmation of the EIA study findings, the Applicant shall comply with the requirements as stipulated in Annex 21 of the TM.
4.3 The Applicant shall prepare a project implementation schedule (in the form of a checklist) containing all the EIA study recommendations and mitigation measures with reference to the implementation programme.
4.4 The Applicant shall propose real-time reporting of monitoring data for the Project through a dedicated internet website.
5. SUMMARY Of ENVIRONMENTAL OUTCOMES
5.1 The EIA report shall contain a summary of the key environmental outcomes arising from the EIA study, including the population and environmentally sensitive areas protected, environmentally friendly designs recommended, key environmental problems avoided, and environmental benefits of environmental protection measures recommended.
6. DURATION OF VALIDITY
6.1 This EIA study brief is valid for 24 months from the date of issue. If the EIA study does not commence within this period, the Applicant shall apply to the Director for a fresh EIA study brief before commencement of the EIA study.
7. REPORT REQUIREMENTS
7.1 In preparing the EIA report, the Applicant shall refer to Annex 11 of the TM for the contents of an EIA report. The Applicant shall also refer to Annex 20 of the TM, which stipulates the guidelines for the review of an EIA report.
7.2 The Applicant shall supply the Director with the following number of copies of the EIA report and the executive summary:
(i) 40 copies of the EIA report in English and 80 copies of the executive summary (each bilingual in both English and Chinese) as required under section 6(2) of the EIAO to be delivered to the EIAO office at the time of application for approval of the EIA report.
(ii) when necessary, addendum to the EIA report and the executive summary submitted in (i) above as required under section 7(1) of the EIAO, to be delivered to the EIAO office upon advice by the Director for public inspection.
(iii) 20 copies of the EIA report in English and 50 copies of the executive summary (each bilingual in both English and Chinese) with or without Addendum as required under section 7(5) of the EIAO, to be delivered to the EIAO office upon advice by the Director for consultation with the Advisory Council on the Environment.
7.3 The Applicant shall make additional copies of the above documents available to the public, subject to payment by the interested parties of full costs of printing.
7.4 In addition, to facilitate the public inspection of the EIA Report via the EIAO Internet Website, the applicant shall provide electronic copies of both the EIA Report and the Executive Summary Report prepared in HyperText Markup Language (HTML) (version 4.0 or later) and in Portable Document Format (PDF version 4.0 or later), unless otherwise agreed by the Director. For the HTML version, a content page capable of providing hyperlinks to each section and sub-section of the EIA Report and the Executive Summary Report shall be included in the beginning of the document. Hyperlinks to all figures, drawings and tables in the EIA Report and Executive Summary shall be provided in the main text from where the respective references are made. All graphics in the report shall be in interlaced GIF format unless otherwise agreed by the Director.
7.5 The electronic copies of the EIA report and the Executive Summary shall be submitted to the Director at the time of application for approval of the EIA Report.
7.6 When the EIA Report and the Executive Summary are made available for public inspection under s.7(1) of the EIA Ordinance, the content of the electronic copies of the EIA Report and the Executive Summary must be the same as the hard copies and the Director shall be provided with the most updated electronic copies.
8. OTHER PROCEDURAL REQUIREMENTS
8.1 During the EIA study, if there is any change in the name of the Applicant for this EIA study brief, the Applicant mentioned in this study brief must notify the Director immediately.
8.2 If there is any key change in the scope of the project mentioned in Section 1 of this EIA study brief and in Project Profile (No. PP-143/2001), the Applicant must seek confirmation from the Director in writing on whether or not the scope of issues covered by this EIA study brief can still cover the key changes, and the additional issues, if any, that the EIA study must also address. If the changes to the project fundamentally alter the key scope of the EIA study brief, the Applicant shall apply to the Director for a fresh EIA study brief.
- END OF EIA STUDY BRIEF -
Guidelines on Choice of Models and Model Parameters
1.1 This paper describes the usage and requirements of a few commonly used air quality models.
2. Choice of Models
2.1 The models which have been most commonly used in air quality impact assessments, due partly to their ease of use and partly to the quick turn-around time for results, are of Gaussian type and designed for use in simple terrain under uniform wind flow. There are circumstances when these models are not suitable for ambient concentration estimates and other types of models such as physical, numerical or mesoscale models will have to be used. In situations where topographic, terrain or obstruction effects are minimal between source and receptor, the following Gaussian models can be used to estimate the near-field impacts of a number of source types including dust, traffic and industrial emissions.
|FDM||for evaluating fugitive and open dust source impacts (point, line and area sources)|
|CALINE4||for evaluating mobile traffic emission impacts (line sources)|
|ISCST3||for evaluating industrial chimney releases as well as area and volumetric sources (point, area and volume sources); line sources can be approximated by a number of volume sources.|
These frequently used models are also referred to as Schedule 1 models (see attached list).
2.2 Note that both FDM and CALINE4 have a height limit on elevated sources (20 m and 10m, respectively). Source of elevation above these limits will have to be modelled using the ISCST3 model or suitable alternative models. In using the latter, reference should be made to the 'Guidelines on the Use of Alternative Computer Models in Air Quality Assessment' in Appendix B-3.
2.3 The models can be used to estimate both short-term (hourly and daily average) and long-term (annual average) ambient concentrations of air pollutants. The model results, obtained using appropriate model parameters (refer to Section 3) and assumptions, allow direct comparison with the relevant air quality standards such as the Air Quality Objectives (AQOs) for the relevant pollutant and time averaging period.
3. Model Input Requirements
3.1 Meteorological Data
3.1.1 At least 1 year of recent meteorological data (including wind speed, wind direction, stability class, ambient temperature and mixing height) from a weather station either closest to or having similar characteristics as the study site should be used to determine the highest short-term (hourly, daily) and long-term (annual) impacts at identified air sensitive receivers in that period. The amount of valid data for the period should be no less than 90 percent.
3.1.2 Alternatively, the meteorological conditions as listed below can be used to examine the worst case short-term impacts:
stability class D; wind speed 1 m/s (at 10m height); worst-case wind angle; mixing height 500 m
stability class F; wind speed 1 m/s (at 10m height); worst case wind angle; mixing height 500 m
This is a common practice with using the CALINE4 model due to its inability to handle lengthy data set.
3.1.3 For situations where, for example, (i) the model (such as CALINE4) does not allow easy handling of one full year of meteorological data; or (ii) model run time is a concern, the followings can be adopted in order to determine the daily and annual average impacts:
(i) perform a frequency occurrence analysis of one year of meteorological data to determine the actual wind speed (to the nearest unit of m/s), wind direction (to the nearest 10o) and stability (classes A to F) combinations and their frequency of occurrence;
(ii) determine the short term hourly impact under all of the identified wind speed, wind direction and stability combinations; and
(iii) apply the frequency data with the short term results to determine the long term (daily / annual) impacts.
Apart from the above, any alternative approach that will capture the worst possible impact values (both short term and long term) may also be considered.
3.1.4 Note that the anemometer height (relative to a datum same for the sources and receptors) at which wind speed measurements were taken at a selected station should be correctly entered in the model. These measuring positions can vary greatly from station to station and the vertical wind profile employed in the model can be grossly distorted from the real case if incorrect anemometer height is used. This will lead to unreliable concentration estimates.
3.1.5 An additional parameter, namely, the standard deviation of wind direction, σΘ, needs to be provided as input to the CALINE4 model. Typical values ofσΘ range from 12o for rural areas to 24o for highly urbanised areas under 'D' class stability. For semi-rural such as new development areas, 18o is more appropriate under the same stability condition. The following reference can be consulted for typical ranges of standard deviation of wind direction under different stability categories and surface roughness conditions.
Ref.(1): Guideline On Air Quality Models (Revised), EPA-450/2-78-027R, United States Environmental Protection Agency, July 1986.
3.2 Emission Sources
All the identified sources relevant to a process plant or a study site should be entered in the model and the emission estimated based on emission factors compiled in the AP-42 (Ref. 2) or other suitable references. The relevant sections of AP-42 and any parameters or assumptions used in deriving the emission rates (in units g/s, g/s/m or g/s/m2) as required by the model should be clearly stated for verification. The physical dimensions, location, release height and any other emission characteristics such as efflux conditions and emission pattern of the sources input to the model should also correspond to site data.
If the emission of a source varies with wind speed, the wind speed-dependent factor should be entered.
Ref.(2): Compilation of Air Pollutant Emission Factors, AP-42, 5thEdition, United States Environmental Protection Agency, January 1995.
3.3 Urban/Rural Classification
Emission sources may be located in a variety of settings. For modelling purposes these are classed as either rural or urban so as to reflect the enhanced mixing that occurs over urban areas due to the presence of buildings and urban heat effects. The selection of either rural or urban dispersion coefficients in a specific application should follow a land use classification procedure. If the land use types including industrial, commercial and residential uses account for 50% or more of an area within 3 km radius from the source, the site is classified as urban; otherwise, it is classed as rural.
3.4 Surface Roughness Height
This parameter is closely related to the land use characteristics of a study area and associated with the roughness element height. As a first approximation, the surface roughness can be estimated as 3 to 10 percent of the average height of physical structures. Typical values used for urban and new development areas are 370 cm and 100 cm, respectively.
These include discrete receptors representing all the identified air sensitive receivers at their appropriate locations and elevations and any other discrete or grid receptors for supplementary information. A receptor grid, whether Cartesian or Polar, may be used to generate results for contour outputs.
3.6 Particle Size Classes
In evaluating the impacts of dust-emitting activities, suitable dust size categories relevant to the dust sources concerned with reasonable breakdown in TSP (< 30 μm) and RSP (< 10 μm) compositions should be used.
3.7 NO2 to NOx Ratio
The conversion of NOx to NO2 is a result of a series of complex photochemical reactions and has implications on the prediction of near field impacts of traffic emissions. Until further data are available, three approaches are currently acceptable in the determination of NO2:
(a) Ambient Ratio Method (ARM) - assuming 20% of NOx to be NO2; or
(b) Discrete Parcel Method (DPM, available in the CALINE4 model); or
(c) Ozone Limiting Method (OLM) - assuming the tailpipe NO2 emission to be 7.5% of NOx and the background ozone concentration to be in the range of 57 to 68 μg/m3 depending on the land use type (see also the reference paper 'Guidelines on Assessing the 'TOTAL' Air Quality Impacts' in Appendix B-2).
3.8 Plume Rise Options
The ISCST3 model provides by default a list of the U.S. regulatory options for concentration calculations. These are all applicable to the Hong Kong situations except for the 'Final Plume Rise' option. As the distance between sources and receptors are generally fairly close, the non-regulatory option of 'Gradual Plume Rise' should be used instead to give more accurate estimate of near-field impacts due to plume emission. However, the 'Final Plume Rise' option may still be used for assessing the impacts of distant sources.
3.9 Portal Emissions
These include traffic emissions from tunnel portals and any other similar openings and are generally modelled as volume sources according to the PIARC 91 (or more up-to-date version) recommendations (Ref. 3, section III.2). For emissions arising from underpasses or any horizontal openings of the like, these are treated as area or point sources depending on the source physical dimensions. In all these situations, the ISCST3 model or more sophisticated models will have to be used instead of the CALINE4 model. In the case of portal emissions with significant horizontal exit velocity which cannot be handled by the ISCST3 model, the impacts may be estimated by the TOP model (Ref. 4) or any other suitable models subject to prior agreement with EPD. The 'Guidelines on the Use of Alternative Computer Models in Air Quality Assessment' should also be referred to in Appendix B-3.
Ref.(3): XIXth World Road Congress Report, Permanent International Association of Road Congresses (PIARC), 1991.
Ref.(4): N. Ukegunchi, H. Okamoto and Y. Ide "Prediction of vehicular emission pollution around a tunnel mouth", Proceedings 4th International Clean Air Congress, pp. 205-207, Tokyo, 1977.
3.10 Background Concentrations
Background concentrations are required to account for far-field sources which cannot be estimated by the model. These values, to be used in conjunction with model results for assessing the total impacts, should be based on long term average of monitoring data at location representative of the study site. Please make reference to the paper 'Guidelines on Assessing the 'TOTAL' Air Quality Impacts' in Appendix B-2 for further information.
The highest short-term and long-term averages of pollutant concentrations at prescribed receptor locations are output by the model and to be compared against the relevant air quality standards specified for the relevant pollutant. Contours of pollutant concentration are also required for indicating the general impacts of emissions over a study area.
Copies of model files in electronic format should also be provided for EPD's reference.
Air Quality Models Generally Accepted by
Hong Kong Environmental Protection Department for
Regulatory Applications as at 1 July 1998
Industrial Source Complex Dispersion Model - Short Term Version 3 (ISCST3) or the latest version developed by U.S. Environmental Protection Agency
California Line Source Dispersion Model Version 4 (CALINE4) or the latest version developed by Department of Transportation, State of California, U.S.A.
Fugitive Dust Model (FDM) or the latest version developed by U.S. Environmental Protection Agency
Guidelines on Assessing the 'TOTAL' Air Quality Impacts
1. Total Impacts - 3 Major Contributions
1.1 In evaluating the air quality impacts of a proposed project upon air sensitive receivers, contributions from three classes of emission sources depending on their distance from the site should be considered. These are:
|Primary contributions:||project induced|
|Secondary contributions:||pollutant-emitting activities in the immediate neighbourhood|
|Other contributions:||pollution not accounted for by the previous two
2. Nature of Emissions
2.1 Primary contributions
In most cases, the project-induced emissions are fairly well defined and quite often (but not necessarily) the major contributor to local air quality impacts. Examples include those due to traffic network, building or road construction projects.
2.2 Secondary contributions
Within the immediate neighbourhood of the project site, there are usually pollutant emitting activities contributing further to local air quality impacts. For most local scale projects, any emission sources in an area within 500m radius of the project site with notable impacts should be identified and included in an air quality assessment to cover the short-range contributions. In the exceptional cases where there is one or more significant sources nearby, the study area may have to be extended or alternative estimation approach employed to ensure these impacts are reasonably accounted for.
2.3 Background contributions
The above two types of emission contributions should account for, to a great extent, the air quality impacts upon local air sensitive receivers, which are often amenable to estimation by the 'Gaussian Dispersion' type of models. However, a background air quality level should be prescribed to indicate the baseline air quality in the region of the project site, which would account for any pollution not covered by the two preceding contributions. The emission sources contributing to the background air quality would be located further afield and not easy to identify. In addition, the transport mechanism by which pollutants are carried over long distances (ranging from 1km up to tens or hundreds of kms) is rather complex and cannot be adequately estimated by the 'Gaussian' type of models.
3. Background Air Quality - Estimation Approach
3.1 The approach
In view of the difficulties in estimating background air quality using the air quality models currently available, an alternative approach based on monitored data is suggested. The essence of this approach is to adopt the long-term (5-year) averages of the most recent monitored air quality data obtained by EPD. These background data would be reviewed yearly or biennially depending on the availability of the monitored data. The approach is a first attempt to provide a reasonable estimate of the background air quality level for use in conjunction with EIA air quality assessment to address the cumulative impacts upon a locality. This approach may be replaced or supplemented by superior modelling efforts such as that entailed in PATH (Pollutants in the Atmosphere and their Transport over Hong Kong), a comprehensive territory-wide air quality modelling system currently being developed for Hong Kong. Notwithstanding this, the present approach is based on measured data and their long term regional averages; the background values so derived should therefore be indicative of the present background air quality. In the absence of any other meaningful way to estimate a background air quality for the future, this present background estimate should also be applied to future projects as a first attempt at a comprehensive estimate until a better approach is formulated.
The monitored air quality data, by 'district-averaging' are further divided into three categories, viz, Urban, Industrial and Rural/New Development. The background pollutant concentrations to be adopted for a project site would depend on the geographical constituency to which the site belongs. The categorisation of these constituencies is given in Section 3.4. The monitoring stations suggested for the 'district-averaging'(arithmetic means) to derive averages for the three background air quality categories are listed as follows:
|Urban:||Kwun Tong, Sham Shui Po, Tsim Sha Tsui and Central/Western|
|Industrial:||Kwun Tong, Tsuen Wan and Kwai Chung|
|Rural/New Development:||Sha Tin, Tai Po, Junk Bay, Hong Kong South and Yuen Long|
The averaging would make use of data from the above stations wherever available. The majority of the monitoring stations are located some 20m above ground.
3.3 Background pollutant values
Based on the above approach, background values for the 3 categories have been obtained for a few major air pollutants as follows:
|POLLUTANT||URBAN||INDUSTRIAL||RURAL / NEW DEVELOPMENT|
All units are in micrograms per cubic metre. The above values are derived from 1992 to 1996 annual averages with the exception of ozone which represent annual average of daily hourly maximum values for year 1996.
In cases where suitable air quality monitoring data representative of the study site such as those obtained from a nearby monitoring station or on-site sampling are not available for the prescription of background air pollution levels, the above tabulated values can be adopted instead. Strictly speaking, the suggested values are only appropriate for long term assessment. However, as an interim measure and until a better approach is formulated, the same values can also be used for short term assessment. This implies that the short term background values will be somewhat under-estimated, which compensates for the fact that some of the monitoring data are inherently influenced by secondary sources because of the monitoring station location.
Indeed, if good quality on-site sampling data which cover at least one year period are available, these can be used to derive both the long term (annual) and short term (daily / hourly) background values, the latter are usually applied on an hour to hour, day to day basis.
3.4 Site categories
The categories to which the 19 geographical constituencies belong are listed as follows:
|DISTRICT||AIR QUALITY CATEGORY|
|Islands||Rural / New Development|
|Southern||Rural / New Development|
|Central & Western||Urban|
|Sai Kung||Rural / New Development|
|Wong Tai Sin||Urban|
|Sham Shui Po||Urban|
|Sha Tin||Rural / New Development|
|Tuen Mun||Rural / New Development|
|Tai Po||Rural / New Development|
|Yuen Long||Rural / New Development|
|Northern||Rural / New Development|
3.5 Provisions for 'double-counting'
The current approach is, by no means, a rigorous treatment of background air quality but aims to provide an as-realistic-as-possible approximation based on limited field data. 'Double-counting' of 'secondary contributions' may be apparent through the use of such 'monitoring-based' background data as some of the monitoring stations are of close proximity to existing emission sources. 'Primary contributions' due to a proposed project (which is yet to be realized) will not be double-counted by such an approach. In order to avoid over-estimation of background pollutant concentrations, an adjustment to the values given in Section 3.3 is possible and optional by multiplying the following factor:
(1.0 - ESecondary contributions/ETerritory)
where E stands for emission.
The significance of this factor is to eliminate the fractional contribution to background pollutant level of emissions due to 'secondary contributions' out of those from the entire territory. In most cases, this fractional contribution to background pollutant levels by the secondary contributions is minimal.
4.1 The above described approach to estimating the total air quality impacts of a proposed project, in particular the background pollutant concentrations for air quality assessment, should be adopted with immediate effect. Use of short term monitoring data to prescribe the background concentrations is no longer acceptable.
Guidelines on the Use of Alternative Computer Models
in Air Quality Assessment
1.1 In Hong Kong, a number of Gaussian plume models are commonly employed in regulatory applications such as application for specified process licences and environmental impact assessments (EIAs). These frequently used models (as listed in Schedule 1 attached; hereafter referred to as Schedule 1 models) have no regulatory status but form the basic set of tools for local-scale air quality assessment in Hong Kong.
1.2 However, no single model is sufficient to cover all situations encountered in regulatory applications. In order to ensure that the best model available is used for each regulatory application and that a model is not arbitrarily applied, the project proponent (and/or its environmental consultants) should assess the capabilities of various models available and adopt one that is most suitable for the project concerned.
1.3 Examples of situations where the use of an alternative model is warranted include:
(i) the complexity of the situation to be modelled far exceeds the capability of the Schedule 1 models; and
(ii) the performance of an alternative model is comparable or better than the Schedule 1 models.
1.4 This paper outlines the demonstration / submission required in order to support the use of an alternative air quality model for regulatory applications for Hong Kong.
2. Required Demonstration / Submission
2.1 Any model that is proposed for air quality applications and not listed amongst the Schedule 1 models will be considered by EPD on a case-by-case basis. In such cases, the proponent will have to provide the followings for EPD's review:
(i) Technical details of the proposed model; and
(ii) Performance evaluation of the proposed model
Based on the above information, EPD will determine the acceptability of the proposed model for a specific or general applications. The onus of providing adequate supporting materials rests entirely with the proponent.
2.2 To provide technical details of the proposed model, the proponent should submit documents containing at least the following information:
(i) mathematical formulation and data requirements of the model;
(ii) any previous performance evaluation of the model; and
(iii) a complete set of model input and output file(s) in commonly used electronic format.
2.3 On performance evaluation, the required approach and extent of demonstration varies depending on whether a Schedule 1 model is already available and suitable in simulating the situation under consideration. In cases where no Schedule 1 model is found applicable, the proponent must demonstrate that the proposed model passes the screening test as set out in USEPA Document "Protocol for Determining the Best Performing Model" (Ref. 1).
2.4 For cases where a Schedule 1 model is applicable to the project under consideration but an alternative model is proposed for use instead, the proponent must demonstrate either that
(i) the highest and second highest concentrations predicted by the proposed model are within 2 percent of the estimates obtained from an applicable Schedule 1 model (with appropriate options chosen) for all receptors for the project under consideration; or
(ii) the proposed model has superior performance against an applicable Schedule 1 model based on the evaluation procedure set out in USEPA Document "Protocol for Determining the Best Performing Model" (Ref. 1).
2.5 Should EPD find the information on technical details alone sufficient to indicate the acceptability of the proposed model, information on further performance evaluation as specified in Sections 2.3 and 2.4 above would not be necessary.
2.6 If the proposed model is an older version of one of the Schedule 1 models or was previously included in Schedule 1, the technical documents mentioned in Section 2.2 are normally not required. However, a performance demonstration of equivalence as stated in Section 2.4 (i) would become necessary.
2.7 If EPD is already in possession of some of the documents that describe the technical details of the proposed model, submission of the same by the proponent is not necessary. The proponent may check with EPD to avoid sending in duplicate information.
Air Quality Models Generally Accepted by
Hong Kong Environmental Protection Department for
Regulatory Applications as at 1 July 1998
Industrial Source Complex Dispersion Model - Short Term Version 3 (ISCST3) or the latest version developed by U.S. Environmental Protection Agency
California Line Source Dispersion Model Version 4 (CALINE4) or the latest version developed by Department of Transportation, State of California, U.S.A.
Fugitive Dust Model (FDM) or the latest version developed by U.S. Environmental Protection Agency
Ref. (1): William M. Cox, "Protocol for Determining the Best Performing Model" Publication No. EPA-454/R-92-025; U.S. Environmental Protection Agency, Research Triangle Park, NC.