Environmental Impact Assessment Ordinance (Cap. 499), Section 5 (7)
Environmental Impact Assessment Study Brief No. ESB-139/2005
Project Title : Widening of Yeung Uk Road between
Tai Ho Road and Ma Tau Pa Road, Tsuen Wan
Name of Applicant : Civil Engineering and Development Department
The Government of the Hong Kong
Special Administrative Region
(hereinafter known as the "Applicant")
1. BACKGROUND
1.1 An application (No. ESB-139/2005) for an Environmental Impact Assessment (EIA) study brief under section 5(1) of the Environmental Impact Assessment Ordinance (EIAO) was submitted by the Applicant on 8 December 2005 with a project profile (No. PP-272/2005) (the Project Profile).
1.2 A study brief (No. ESB-012/1998) for the same project title was issued under the EIAO on 29 September 1998. The current application for a new study brief was made as the applicant considers that part of the project scope has been changed.
1.3 The Project under the current application (hereinafter known as the “Project”) is mainly to widen Yeung Uk Road between Tai Ho Road and Ma Tau Pa Road in Tsuen Wan from dual 2- to dual-3 lane carriageways. The scope of the Project, as shown in Figures 1 and 2 in Appendix A, are as follows :
(i) widening of about 550 metres long Yeung Uk Road between Tai Ho Road and Ma Tau Pa Road from dual two-lane to dual three-lane carriageways;
(ii) construction of service laybys and a westbound service road at Yeung Uk Road;
(iii) realignment of about 200 metres long Ma Tau Pa Road and provision of a service layby thereat;
(iv) removal of existing structures including the electricity substation and those at the ex-sport ground at Yeung Uk Road;
(v) associated works for landscaping, drainage, traffic aids, noise mitigation measures, E&M and utilities diversions; and
(vi) remaining works for modifications to two junctions of Yeung Uk Road with Ma Tau Pa Road and Tai Ho Road arising from nearby developments.
1.4 The Project is a designated project under Schedule 2, A.1 of the EIAO : “A road which is an expressway, trunk road, primary distributor road or district distributor road including new roads, and major extensions or improvements to existing roads”.
1.5 Pursuant to section 5(7)(a) of the EIAO, the Director of Environmental Protection (the Director) issues this EIA study brief to the Applicant to carry out an EIA study.
1.6 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 Project and related activities that take 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 as a result of the Project;
(ii) the conditions and requirements for the detailed design, construction and 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 associated works together with the requirements for carrying out the Project;
(ii) to identify and describe elements of community and environment likely to be affected by the Project and/or likely to cause adverse impacts to the Project, including natural and man-made environment and the associated environmental constraints;
(iii) to provide information on the consideration of alternatives to avoid and minimize potential environmental impacts to sensitive uses; to compare the environmental benefits and dis-benefits of each of different options; to provide reasons for selecting the preferred option(s) and to describe the part environmental factors played in the selection of preferred option(s);
(iv) to identify and quantify emission sources and determine the significance of impacts on sensitive receivers and potential affected uses;
(v) to identify and quantify any potential landscape and visual impacts and to propose measures to mitigate these impacts;
(vi) to propose the provision of mitigation measures so as to minimize pollution, environmental disturbance and nuisance during construction and operation of the Project;
(vii) to investigate the feasibility, practicability, effectiveness and implications of the proposed mitigation measures;
(viii) to identify, predict and evaluate the residual environmental impacts (i.e. after practicable mitigation) and the cumulative effects expected to arise during the construction and operation phases of the Project in relation to the sensitive receivers and potential affected uses;
(ix) 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 cumulative effects and reduce them to acceptable levels;
(x) to investigate the extent of the secondary environmental impacts that may arise from the proposed mitigation measures and to identify constraints associated with the mitigation measures recommended in the EIA study, as well as the provision of any necessary modification; and
(xi) to design and specify environmental monitoring and audit requirements to ensure the effective implementation of the recommended environmental protection and pollution control measures.
3. DETAILED REQUIREMENTS OF THE EIA STUDY
3.1 The Purpose
The purpose of this study brief is to scope the key issues of 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 Process of the Environmental Impact Assessment Ordinance (hereinafter referred to as “the TM”) are fully complied with.
3.2 The Scope
3.2.1 The scope of this EIA study shall cover the Project mentioned in sub-section 1.3 above. 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) the potential air and noise quality impacts from the construction and operation of the Project to sensitive receivers along or near the Project, taking into account the cumulative impact from the operation of existing roads in the vicinity of the Project;
(ii) potential water quality impact from the construction and operation of the Project on the relevant water systems;
(iii) waste arising as a result of the construction and operation activities of the Project; potential land contamination from land clearance for the Project and;
(iv) potential landscape & visual impacts from construction and operation of the project.
3.3 Consideration of Alternatives
3.3.1 The Need of the Project
The Applicant shall study and review the need of the Project as mentioned in sub-section 1.3 above, and provide information to justify the need. The Applicant shall explain clearly the purpose and objectives of the Project and describe the scenarios with and without the Project.
3.3.2 Consideration of Different Alignment Options and Built-forms
In addition to the proposed alignment option mentioned in sub-section 1.3 above, the Applicant shall consider other feasible alignment options for the Project, provide justification regarding how the proposed scheme is arrived at, including the descriptions of the environmental factors considered in the option selection. Alternative built-forms (such as submerged and/ semi-submerged designs for the proposed alignment) and design of the highway shall be reviewed and investigated. A comparison of the environmental benefits and dis-benefits of possible alignment options and alternative built-forms and design shall be made with a view to recommending the preferred option to avoid/minimize adverse environmental effects to the maximum practicable extent. In particular, consideration shall be given to avoid or minimize operational potential noise and air quality impacts to the adjacent sensitive receivers.
3.3.3 Consideration of Alternative Construction Methods and Sequences of Works
Taking into consideration the combined effect with respect to the severity and duration of the construction impacts to the affected sensitive receivers, the EIA study shall explore alternative construction methods and sequences of works for the Project, with a view to avoid prolonged adverse environmental impacts to the maximum practicable extent. A comparison of the environmental benefits and dis-benefits of applying different construction methods and sequence of works shall be made.
3.3.4 Selection of Preferred Scenario
Taking into consideration of the findings in sub-sections 3.3.2 and 3.3.3 above, the Applicant shall recommend/justify the adoption of the preferred scenario that will avoid or minimize adverse environmental effects arising from the Project, and adequately describe the part that environmental factors played in arriving at the final selection.
3.4 Technical Requirements
The Applicant shall conduct the EIA study to address all environmental aspects as described in sub-sections 3.1, 3.2 and 3.3 above. The EIA study shall include the following technical requirements on specific impacts.
3.4.1 Air Quality Impact
3.4.1.1 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.
3.4.1.2 The study area for air quality impact assessment shall generally be defined by a distance of 500 metres from the boundary of the Project site, yet it shall be extended to include major emission sources that may have a bearing on the environmental acceptability of the Project. Such assessment shall be based on the best available information at the time of the assessment. In particular, the assessment for the operation stage shall take into account the impacts of major emission sources such as Tsuen Wan Road, whereas the assessment for the construction stage shall take into account the impacts of major emission sources from other nearby concurrent, construction projects, if any.
3.4.1.3 The Applicant shall assess the air pollutant concentrations in accordance with the Guidelines for Local-Scale Air Quality Assessment Using Models given in Appendices B1 to B3, or other methodology as agreed by the Director (The Applicant shall note that the “Odour Impact” in sub-section 3.8 of Appendix B-1 is unlikely to be relevant to this Project unless there are major changes in the Project or circumstances during the course of this EIA study).
3.4.1.4 The air quality impact assessment shall include the following:
(i) 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 of the Project that may affect air quality during both construction and operation stages.
(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 shall consider alternative construction methods / phasing programmes and alternative modes of operation to minimize the constructional and operational air quality impact respectively.
(c) Present the background air quality levels in the assessment area for the purpose of evaluating the cumulative constructional and operational air quality impacts.
(ii) Identification of Air Sensitive Receivers (ASRs) and Examination of Emission/Dispersion Characteristics
(a) Identify and describe representative existing and planned/committed ASRs that are likely affected by the Project, including those earmarked on relevant Outline Zoning Plans, Development Permission Area Plans, Outline Development Plans, Layout Plans and other relevant published land use plans (e.g. Kowloon-Canton Railway Corporation (KCRC)’s TW5 developments, Skyline Plaza, Urban Renewal Authority (URA) ’s residential development at Tsuen Wan Town Lot (TWTL) 398, 5-storey buildings at 67 Yeung Uk Road, Tsuen Wan Caritas Clinic, Mary of Providence Primary School, Shek Pik New Village, the Chinese Rhenish Church Tsuen Wan, Harmony Garden Blocks 1 and 2, URA’s residential development at TWTL 394, etc). The Applicant shall select the assessment points of identified ASRs that represent the worst impact point of these ASRs. A map showing the location and description such as name of building, use and height of selected assessment points shall be given. Separation distances of these ASRs from nearest emission sources shall also be given.
(b) Provide an exhaustive list of air pollutant emission sources, including any nearby emission sources which are likely to have impact related to the Project based on the analysis of the constructional and operational activities in sub-section 3.4.1.4(i) above. Examples of construction stage emission sources include stock piling, blasting, concrete batching and vehicular movements on unpaved haul roads on site, etc. Examples of operational stage emission sources include exhaust emissions from vehicles etc. Confirmation regarding the validity of assumptions and the magnitude of activities (e.g. volume of construction material handled, traffic mix and volume on a road etc.) shall be obtained from the relevant government departments/authorities and documented.
(iii) Construction Phase Air Quality Impact
(a) The Applicant shall follow requirements stipulated under Air Pollution Control (Construction Dust) Regulation to ensure construction dust impacts are controlled within relevant standards stipulated in section 1 of Annex 4 of the TM. A construction phase monitoring and audit programme shall be devised to verify effectiveness of control measures to ensure proper construction dust control.
(b) If the Applicant anticipates that the Project will give rise to significant construction dust impacts likely to exceed the recommended limits in the TM at the ASRs despite the incorporation of dust control measures proposed in accordance with sub-section 3.4.1.4(iii)(a) above, a quantitative assessment shall be carried out to evaluate the construction dust impact at identified ASRs. The Applicant shall follow the methodology set out in sub-section 3.4.1.4(v) below when carrying out the quantitative assessment.
(iv) Operational Phase Air Quality Impact
(a) The Applicant shall calculate the expected air pollutant concentrations at the identified ASRs based on an assumed reasonably worst-case scenario under normal operating condition. The evaluation shall be based on the strength of the emission sources identified in sub-section 3.4.1.4(ii)(b) above. The Applicant shall follow sub-section 3.4.1.4(v) below when carrying out the quantitative assessment.
(b) The air pollution impacts of future road traffic shall be calculated based on the highest emission strength from the road within the next 15 years upon commencement of operation of the Project. 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. The Fleet Average Emission Factors used in the assessment shall be agreed with the Director. If necessary, the Fleet Average Emission Factors shall be determined by a motor vehicle emission model such as EMFAC-HK model to be agreed with the Director. All the traffic flow data and assumptions that used in the assessment shall be clearly and properly documented in the EIA report.
(c) If full enclosures are proposed in the Project, it is the responsibility of the Applicant to ensure that the air quality inside these proposed structures shall comply with EPD's “Practice Note on Control of Air Pollution in Vehicle Tunnels”. When assessing air quality impact due to emissions from full enclosures, the Applicant shall ensure prior agreement with the relevant ventilation design engineer over the amount and the types/kinds of pollutants emitted from these full enclosures; and such assumptions shall be clearly and properly documented in the EIA report.
(v) Quantitative Assessment Methodology
(a) The Applicant shall conduct the quantitative assessment with reference to relevant sections of the modelling guidelines stated in section 3.4.1.3 or any other methodology as agreed with the Director. The specific methodology must be documented in such level of details (preferably with tables and diagrams) to allow the readers of the EIA report to grasp how the model has been set up to simulate the situation at hand without referring to the model input files. Detailed calculation of the pollutant emission rates for input to the model and a map showing all the road links shall be presented in the EIA report. The Applicant shall ensure consistency between the text description and the model files at every stage of submissions for review. In case of doubt, prior agreement between the Applicant and the Director on specific modelling details shall be sought.
(b) The Applicant shall identify the key/representative air pollutant parameters (types of pollutants and the averaging time concentrations) to be evaluated and provide explanation for choosing such parameters for assessing the impact of the Project.
(c) The Applicant shall calculate the cumulative air quality impact 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, to be evaluated against the relevant air quality standards and on any effect they may have on the land use implications. Plans of a suitable scale shall be used to present pollution contour to allow buffer distance requirements to be determined properly.
(d) If there are any direct technical noise remedies recommended in the study, the air quality implication due to these technical remedies shall be assessed. For instance, if barriers that may affect dispersion of air pollutants are proposed, then the implications of such remedies on air quality impact shall be assessed. If noise enclosure, submerged/ semi-submerged road design is proposed, then portal emissions of the enclosed road section and air quality inside the enclosed road section shall also be addressed. The Applicant shall highlight clearly the locations and types of agreed noise mitigating measures (where applicable), be they noise barriers, road enclosures and their portals, and affected ASR's, on contour maps for easy reference.
(vi) Mitigation Measures for Non-compliance
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 in the EIA report. 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.
(vii) Submission of Model Files
All input and output file(s) of the model run(s) shall be submitted to the Director in electronic format.
3.4.2 Noise Impact
3.4.2.1 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.
3.4.2.2 The noise impact assessment shall include the following :
(i) Determination of Assessment Area
The study area for the noise impact assessment shall generally include all areas within 300m from the Project shown in Appendix A or other Project alignments as identified in the EIA. Subject to the agreement of the Director, the assessment area could be reduced accordingly if the first layer of noise sensitive receivers (NSRs), closer than 300m from the outer Project limit, provides acoustic shielding to those receivers at distances further away from the Project. Subject to the agreement of the Director, the assessment area shall be expanded to include NSRs at distances over 300m from the Project, which are affected by the construction and operation of the Project.
(ii) Provision of Background Information and Existing Noise Levels
The Applicant shall provide all background information relevant to the Project, e.g. relevant previous or current studies. Unless required for determining the planning standards, e.g. those for planning of fixed noise sources (such as ventilation systems of traffic noise enclosures), no existing noise levels are particularly required.
(iii) Identification of Noise Sensitive Receivers
(a) The Applicant shall refer to Annex 13 of the TM when identifying the NSRs. The NSRs shall include all existing NSRs and all planned/committed noise sensitive developments and uses, including but not limiting to KCRC’s TW5 developments, Skyline Plaza, Tsuen Wan Plaza Blocks 1 and 2, URA’s residential development at TWTL 398, the Blue Yard, 5-storey buildings at 67 Yeung Uk Road, Tsuen Wan Caritas Clinic, Mary of Providence Primary School, Shek Pik New Village, St. Francis Xavier’s School, Jade Plaza, Bo Shek Mansion Blocks 1 and 3, the Chinese Rhenish Church Tsuen Wan, Harmony Garden Blocks 1 and 2, URA’s residential development at TWTL 394, etc., earmarked on the relevant Outline Zoning Plans, Development Permission Area Plans, Outline Development Plans, Layout Plans and other relevant published land use plans. Photographs of all existing NSRs shall be appended to the EIA report.
(b) The Applicant shall select assessment points to represent all identified NSRs for carrying out 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 such as name of building, use, and floor of each and every selected assessment point shall be given. For planned noise sensitive land uses without committed site layouts, the Applicant shall use the relevant planning parameters to work out representative site layouts for operational noise assessment purpose.
(iv) Provision of an Emission Inventory of the Noise Sources
The Applicant shall provide an inventory of noise sources including representative construction equipment for construction noise assessment, and traffic flow/ fixed plant equipment (e.g. ventilation systems of traffic noise enclosures), as appropriate, for operational noise assessment. Confirmation of the validity of the inventory shall be obtained from the relevant government departments/authorities and documented in the EIA report.
(v) Construction Noise Assessment
(a) The assessment shall cover the cumulative noise impacts due to the construction works of the Project and other concurrent projects identified during the course of the EIA study.
(b) The Applicant shall carry out assessment of noise impact from construction (excluding percussive piling) of the Project during daytime, i.e. 7 a.m. to 7 p.m., on weekdays other than general holidays in accordance with the methodology in paragraphs 5.3. and 5.4 of Annex 13 of the TM. The criteria in Table 1B of Annex 5 of the TM shall be adopted in the assessment.
(c) To minimize the construction noise impact, alternative construction methods to replace percussive piling shall be proposed as far as practicable. In case blasting works is involved, it shall be carried out, as far as practicable, outside the sensitive hours of 7 p.m. to 7 a.m. on Monday to Saturday and any time on a general holiday, including Sunday. For blasting that must be carried out during the above-mentioned sensitive hours, the noise impact from the removal of debris and rocks shall be fully assessed and adequate mitigation measures shall be recommended to reduce the noise impact.
(d) If the unmitigated construction noise levels are found exceeding 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.
(e) The Applicant shall, as far as practicable, formulate a reasonable construction programme so that no work will be required in restricted hours as defined under the Noise Control Ordinance (NCO). In case the Applicant needs to evaluate whether construction works in restricted hours as defined under the NCO are feasible or not in the context of programming construction works, reference shall be made to relevant technical memoranda issued under the NCO. Regardless of the results of construction noise impact assessment for restricted hours, the Noise Control Authority will process Construction Noise Permit (CNP) application, if necessary, based on the NCO, the relevant technical memoranda issued under the NCO, and the contemporary conditions/situations. This aspect shall be explicitly stated in the noise chapter and the conclusions and recommendations chapter in EIA report.
(vi) Operational Noise Assessment
(a) Road Traffic Noise
(a1) Calculation of Noise Levels
The Applicant shall analyse the scope of the Project to identify road sections within the meaning of Item A.1 of Schedule 2 of EIAO and other road sections for the purpose of traffic noise impact assessment. Figures showing extents of road sections within the meaning of Item A.1 of Schedule 2 of EIAO and other road sections shall be provided in the EIA report. In determining whether the traffic noise impact due to a road improvement project / work is considered significant, detailed information with respect to factors including change of nature of road, change of alignment and change of traffic capacity or traffic composition etc. shall be assessed. The traffic noise impact shall be considered significant if the traffic noise level with the road project is greater than that without the road project at the design year by 1.0 dB(A) or more.
The Applicant shall calculate expected road traffic noise using methods described in the U.K. Department of Transport's “Calculation of Road Traffic Noise” (1988). Calculations of future road traffic noise shall be based on peak hour traffic flow in respect of maximum traffic projection within a 15 years period upon commencement of operation of the Project. The Applicant shall calculate traffic noise levels in respect of each road section and the overall noise levels from combined road sections ( road sections within the meaning of Item A.1 of Schedule 2 of EIAO and other road sections ) at NSRs.
The EIA report shall contain sample calculations and input parameters for at least 10 assessment points as requested by the Director. Also, the Applicant shall provide the input data set of the traffic noise model in the format of electronic files in the EIA. The Applicant shall prepare and provide drawings (i.e., road-plots of the traffic noise model) of appropriate scale to show the road segments, topographic barriers, and assessment points of sensitive receivers input into the traffic noise model.
The Applicant shall provide input data sets of traffic noise prediction model adopted in the EIA study as requested by the Director for the following scenarios:
(1) unmitigated scenario at assessment year;
(2) mitigated scenario at assessment year; and
(3) prevailing scenario for indirect technical remedies eligibility assessment;
The data shall be in electronic text file (ASCII format) containing road segments, barriers and noise sensitive receivers information. The data structure of the above file shall be agreed with the Director. CD-ROM(s) containing the above data shall be attached in the EIA report.
(a2) Presentation of Noise Levels
The Consultants shall present the existing and future noise levels in L10 (1 hour) at the NSRs at various representative floor levels in (m P.D.) on tables and plans of suitable scale.
A quantitative assessment at the NSRs for road sections within the meaning of Item A.1 of Schedule 2 of EIAO shall be carried out and compared against the criteria set out in Table 1A of Annex 5 of the TM. The potential noise impact of road sections within the meaning of Item A.1 of Schedule 2 of EIAO shall be quantified by estimating the total number of dwellings, classrooms and other noise sensitive elements that will be exposed to noise levels exceeding the criteria set in Table 1A of Annex 5 in the TM.
(a3) Proposals for Noise Mitigation Measures
The Applicant shall propose in accordance with Section 6 in Annex 13 of the TM direct technical remedies in all situations where predicted traffic noise level due to the road sections within the meaning of Item A.1 of Schedule 2 of EIAO, exceeds the criteria in Table 1A of Annex 5 in the TM by 1 dB(A) or more, and, under section 4.4.3 of the TM, noise from the road sections within the meaning of Item A.1 of Schedule 2 of EIAO has significant contribution to the cumulative environmental impacts which would exceed the criteria when considered in conjunction with the existing or potential impacts from other projects. Specific reasons for not adopting certain direct technical remedies in the design to reduce the traffic noise to a level meeting the criteria in the TM or to maximize the protection for NSRs as far as possible shall be clearly quantified and laid down. Total number of dwellings, classrooms and other noise sensitive element that will benefit from and be protected by provision of direct technical remedies shall be provided. In order to clearly present the extents/locations of recommended noise mitigation measures, plans prepared from 1:1000 or 1:2000 survey maps showing the mitigation measures (e.g., enclosures/barriers, low noise road surfacing, etc.) shall be included in the EIA report.
The total number of dwellings, classrooms and other noise sensitive elements that will still be exposed to noise levels above the criteria with the implementation of all recommended direct technical remedies shall be quantified. The Applicant shall provide in the EIA report information of recommended noise mitigation measures (such as barrier types, nominal dimensions at different cross-sections, extents/locations, lengths, mPD levels of barriers) in electronic format as agreed by the Director.
In case where a number of NSRs cannot be protected by the recommended direct technical remedies, the Applicant shall identify and estimate the total number of existing dwellings, classrooms and other noise sensitive elements which may qualify for indirect technical remedies under the Executive Council Directive “Equitable Redress for Persons Exposed to Increased Noise Resulting from the Use of New Roads”, the associated costs and any implications for such implementation. For the purpose of determining eligibility of the affected premises for indirect technical remedies, reference shall be made to the following set of three criteria :
(1) the predicted overall noise level at the NSR from the road sections within the meaning of Item A.1 of Schedule 2 of EIAO together with other traffic noise in the vicinity must be above a specified noise level ( e.g. 70 dB(A) for domestic premises and 65 dB(A) for education institutions, all in L10(1hr) );
(2) the predicted overall noise level at the NSR is at least 1.0 dB(A) more than the prevailing traffic noise level, i.e. the total traffic noise level existing before the works to construct the road were commenced; and
(3) the contribution from the road sections within the meaning of Item A.1 of Schedule 2 of EIAO to the increase in predicted overall noise level at the NSR must be at least 1.0dB(A).
(b) Fixed Noise Sources
If the Project will cause any fixed noise sources, such as the ventilation systems of enclosed road sections, if any, the following assessment shall be followed.
(b1) Assessment of Fixed Source Noise Levels
The Applicant shall calculate the expected noise using standard acoustics principles. Calculations for the expected noise shall be based on assumed plant inventories and utilization schedule for the worst-case scenario. The Applicant shall calculate noise levels taking into account correction of tonality, impulsiveness and intermittency in accordance with Technical Memorandum for the Assessment of Noise from Places other than Domestic Premises, Public Places or Construction Sites issued under the NCO.
(b2) Presentation of Noise Levels
The Applicant shall present the existing and future noise levels in Leq (30 min) at the NSRs at various representative floor levels (in m P.D.) on tables and plans of suitable scale. A quantitative assessment at the NSRs for the proposed fixed noise source(s) shall be carried out and compared against the criteria set out in Table 1A of Annex 5 of the TM.
(b3) Proposals for Noise Mitigation Measures
The Applicant shall propose direct technical remedies within the Project limits in all situations where the predicted noise level exceeds the criteria set out in Table 1A of Annex 5 of the TM to protect the affected NSRs.
(vii) Assessment of Side Effects and Constraints
The Applicant shall identify, assess and propose means to minimize any side effects and to resolve any potential constraints due to the inclusion of any recommended direct technical remedies.
(viii) Evaluation of Constraints on Planned Noise Sensitive Developments/Land uses
For planned noise sensitive uses which will still be affected even with all practicable direct technical remedies in place, the Applicant shall propose, evaluate and confirm the practicability of additional measures within the planned noise sensitive uses and shall make recommendations on how these noise sensitive uses will be designed for the information of relevant parties.
The Applicant shall take into account agreed environmental requirements / constraints identified by the EIA study to assess the development potential of concerned sites which shall be made known to the relevant parties.
3.4.3 Water Quality Impact
3.4.3.1 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.
3.4.3.2 The Study Area shall include all areas within 300m from the Project boundary, and shall cover relevant sensitive receivers that have a bearing on the environmental acceptability of the Project within the Western Buffer Water Control Zone.
3.4.3.3 All physical, chemical and biological disruptions of the Western Buffer Water Control Zone, waterworks reserve, fresh/storm water or ground water system(s) within the study area arising during the construction and operation of the Project shall be identified.
3.4.3.4 The water quality impact assessment shall address the followings:
General
(i) Collection and review of background information on the existing and planned water system(s), waterworks reserve and sensitive receivers which might be affected by the Project.
(ii) Characterization of water quality based on existing information or site surveys/tests as appropriate.
(iii) Identification and analysis of all existing and planned future activities and beneficial uses related to the water system(s) and identification of all water sensitive receivers.
(iv) Identification of pertinent water quality objectives and establishment of other appropriate water quality criteria or standards for the water system(s) and all the sensitive receivers.
(v) Review the specific construction methods and configurations, and operation of the Project. Identification of any alteration of watercourses.
(vi) Identification, analysis and quantification of all existing and likely future water pollution sources, including point discharges and non-point sources to surface water runoff. Field investigation and laboratory tests shall be conducted as appropriate. Establishment and provision of an emission inventory on the quantities and characteristics of all these pollution sources.
Impact Prediction
(vii) Prediction and quantification of the impacts on the water system(s) and the sensitive receivers due to those alterations and changes identified in (v) and the pollution sources identified in (vi). The prediction shall take into account and include likely different construction stages or sequences, different operation stages.
(viii) Cumulative impacts due to other projects, activities or pollution sources within a boundary around the Study Area to be agreed by the Director shall also be predicted and quantified.
Waste Water and Non-point Sources Pollution
(ix) Analysis on the provision and adequacy of existing and planned future facilities to reduce pollution arising from the non-point sources identified in (vi).
(x) Proposal of effective and practicable infrastructure upgrading or provision, water pollution prevention and mitigation measures to be implemented during the construction and operation stages so as to reduce the water quality impacts to within acceptable levels of standards. Requirements to be incorporated in the Project contract document shall also be proposed.
(xi) Best management practices to reduce storm water and non-point source pollution shall be investigated and proposed as appropriate. Attention shall be made to the water quality control and mitigation measures recommended in ProPECC Note 1/94 on construction site drainage.
(xii) Evaluation and quantification of residual impacts on the water system(s) and the sensitive receivers with regard to the appropriate water quality criteria, standards or guidelines.
3.4.4 Waste Management Implications
3.4.4.1 The Applicant shall follow the criteria and guidelines for evaluating and assessing waste management implications as stated in Annexes 7 and 15 of the TM respectively.
3.4.4.2 The assessment of waste management implications shall cover the following:
(i) Analysis of Activities and Waste Generation
The Applicant shall identify the quantity, quality and timing of the waste arising as a result of the construction and operation activities of the Project, based on the sequence and duration of these activities.
(ii) Proposal for Waste Management
(a) Prior to considering the disposal options for various types of wastes, opportunities for reducing waste generation, on-site or off-site re-use and recycling shall be fully evaluated. Measures which can be taken in the planning and design stages e.g. by modifying the design approach and in the construction stage for maximizing waste reduction shall be separately considered.
(b) After considering all the opportunities for reducing waste generation and maximizing re-use, the types and quantities of the wastes required to be disposed of as a consequence shall be estimated and the disposal options for each type of waste shall be described in detail. Pre-treatment processes for slurry before disposal shall be addressed in details. The disposal method recommended for each type of waste shall take into account of the result of the assessment in (c) below.
(c) The impact caused by handling (including labelling, packaging & storage), collection, and disposal of wastes shall be addressed in detail and appropriate mitigation measures shall be proposed. This assessment shall cover the following areas :
- potential hazard;
- air and odour emissions;
- noise;
- wastewater discharge; and
- public transport.
(iii) Land Contamination
(a) The Applicant shall identify all land lots/sites within the Project boundary which, due to their past or present land uses, are potentially contaminated sites. A detailed account of the present activities and past land use history in relation to possible land contamination shall be provided.
(b) The list of potential contaminants which are anticipated to be found in these potentially contaminated sites shall be provided and the possible remediation options shall be discussed.
3.4.5 Landscape and Visual Impact
3.4.5.1 The Applicant shall summarize any potential landscape and visual impact including the impact arising from the proposed noise mitigation measures of the Project (e.g. noise barriers/enclosures) during the construction and operation stages, based on the criteria and guidelines for evaluating and assessing landscape and visual impact, as stated in Annex 10 and 18 of the TM respectively.
3.4.5.2 Study areas for landscape impact assessment shall include all areas within 100m from the Project. Study area for visual impact assessment shall be defined by the visual envelope of the Project. The defined visual envelope must be shown on a plan in the EIA report.
3.4.5.3 Annotated illustration materials such as plans and computer-generated photomontage shall be adopted to illustrate the landscape and visual impacts.
3.4.5.4 If significant impact is identified, the Applicant shall approach the Director for detailed requirements for the assessment of landscape and visual impact.
3.4.6 Summary of Environmental Outcomes
The EIA report shall contain a summary of key environmental outcomes arising from the EIA study, including the population and environmentally sensitive areas protected, environmentally friendly designs recommended, key environmental problems avoided, compensation areas included and the environmental benefits of environmental protection measures recommended.
3.4.7 Environmental Monitoring and Audit (EM&A) Requirements
3.4.7.1 The Applicant shall identify and justify in the EIA study whether there is any need for EM&A activities during the construction and operation phases of the Project and, if affirmative, to define the scope of EM&A requirements for the Project in the EIA study.
3.4.7.2 Subject to the confirmation of the EIA study findings, the Applicant shall comply with the requirements as stipulated in Annex 21 of the TM. The Applicant shall also propose real-time reporting of monitoring data for the Project through a dedicated internet website.
3.4.7.3 The Applicant shall prepare a Project Implementation Schedule (in the form of a checklist as shown in Appendix C to this EIA study brief) containing all the EIA study recommendations and mitigation measures with reference to the implementation programme. The Project Implementation Schedule shall include the explicit agreement reached between the Applicant and relevant parties on the responsibility for funding, implementation, management and maintenance of mitigation measures. Alternatively, the Project Implementation Schedule shall include an undertaking from the Applicant to assume the responsibility of all those mitigation measures until an agreement is reached between the Applicant and relevant parties on the funding, implementation, management and maintenance of mitigation measures.
4. DURATION OF VALIDITY
4.1 The Applicant shall notify the Director of the commencement of the EIA study. If the EIA study does not commence within 36 months after the date of issue of the EIA study brief, the Applicant shall apply to the Director for a fresh EIA study brief before commencement of the EIA study.
5. REPORT REQUIREMENTS
5.1 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.
5.2 The Applicant shall supply the Director with the following number of copies of the EIA report and the executive summary:
(i) 50 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 supplied 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 sub-section 5.2 (i) above as required under section 7(1) of the EIAO, to be supplied 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 supplied upon advice by the Director for consultation with the Advisory Council on the Environment.
5.3 The Applicant shall, upon request, make additional copies of above documents available to the public, subject to payment by the interested parties of full costs of printing.
5.4 In addition, to facilitate public inspection of EIA report via EIAO Internet Website, the Applicant shall provide electronic copies of both the EIA report and executive summary 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 hyperlink to each section and sub-section of the EIA report and executive summary 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 respective references are made. All graphics in the report shall be in interlaced GIF format unless otherwise agreed by the Director.
5.5 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.
5.6 When the EIA report and the executive summary are made available for public inspection under section 7(1) of the EIAO, 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.
5.7 To promote environmentally friendly and efficient dissemination of information, both hardcopies and electronic copies of future EM&A reports recommended by the EIA study shall be required and their format shall be agreed by the Director.
6. OTHER PROCEDURAL REQUIREMENTS
6.1 If there is any change in the name of Applicant for this EIA study brief during the course of the EIA study, the Applicant must notify the Director immediately.
6.2 If there is any key change in the scope of the Project mentioned in sub-section 1.3 of this EIA study brief and in Project Profile (No. PP-272/2005), 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 ---
January 2006
Environmental Assessment Division,
Environmental Protection Department
Appendix B-1
Guidelines on Choice of Models and Model Parameters in Air Quality Assessment
[The information contained in this Appendix is only meant to assist the Applicant in performing the air quality assessment. The Applicant must exercise professional judgment in applying this general information for the Project.]
1. Introduction
1.1 To expedite the review process by the Authority and to assist project proponents or environmental consultants with the conduct of air quality modelling exercise which are frequently called for as part of environmental impact assessment studies, 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.
Model Applications
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:
Day time: stability class D; wind speed 1 m/s (at 10m height); worst-case wind angle; mixing height 500 m
Night time: 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 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, 5th Edition, 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 classified 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 classified 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.
3.5 Receptors
These include discrete receptors representing all 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 EPD reference paper 'Guidelines on Assessing the 'TOTAL' Air Quality Impacts' in Appendix B-2).
3.8 Odour Impact
In assessing odour impacts, a much shorter time-averaging period of 5 seconds is required due to the shorter exposure period tolerable by human receptors. Conversion of model computed hourly average results to 5-second values is therefore necessary to enable comparison against recommended standard. The hourly concentration is first converted to 3-minute average value according to a power law relationship which is stability dependent (Ref. 3) and a result of the statistical nature of atmospheric turbulence. Another conversion factor (10 for unstable conditions and 5 for neutral to stable conditions) is then applied to convert the 3-minute average to 5-second average (Ref. 4). In summary, to convert the hourly results to 5-second averages, the following factors can be applied:
Stability Category 1-hour to 5-sec Conversion Factor
A & B 45
C 27
D 9
E & F 8
Under ‘D’ class stability, the 5-second concentration is approximately 10 times the hourly average result. Note, however, that the combined use of such conversion factors together with the ISCST results may not be suitable for assessing the extreme close-up impacts of odour sources.
Ref.(3): Richard A. Duffee, Martha A. O’Brien and Ned Ostojic, ‘Odor Modeling – Why and How’, Recent Developments and Current Practices in Odor Regulations, Controls and Technology, Air & Waste Management Association, 1991.
Ref.(4): A.W.C. Keddie, ‘Dispersion of Odours’, Odour Control – A Concise Guide, Warren Spring Laboratory, 1980.
3.9 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.
3.10 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. 5, 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. 6) or any other suitable models subject to prior agreement with EPD. The EPD’s 'Guidelines on the Use of Alternative Computer Models in Air Quality Assessment' should also be referred to in Appendix B-3.
Ref.(5): XIXth World Road Congress Report, Permanent International Association of Road Congresses (PIARC), 1991.
Ref.(6): 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.
3.11 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.
3.11 Output
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.
----------------------------------------------------------------------------------------------------------------------------
Schedule 1
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
*
* EPD is continually reviewing the latest development in air quality models and will update this Schedule accordingly.
Appendix B-2
Guidelines on Assessing the 'TOTAL' Air Quality Impacts
[The information contained in this Appendix is only meant to assist the Applicant in performing the air quality assessment. The Applicant must exercise professional judgment in applying this general information for the Project.]
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
(Background contributions)
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.
3.2 Categorisation
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 |
|
NO2 |
59 |
57 |
39 |
|
SO2 |
21 |
26 |
13 |
|
O3 |
62 |
68 |
57 |
|
TSP |
98 |
96 |
87 |
|
RSP |
60 |
58 |
51 |
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 |
|
Eastern |
Urban |
|
Wan Chai |
Urban |
|
Central & Western |
Urban |
|
Sai Kung |
Rural / New Development |
|
Kwun Tong |
Industrial |
|
Wong Tai Sin |
Urban |
|
Kowloon City |
Urban |
|
Yau Tsim |
Urban |
|
Mong Kok |
Urban |
|
Sham Shui Po |
Urban |
|
Kwai Tsing |
Industrial |
|
Sha Tin |
Rural / New Development |
|
Tsuen Wan |
Industrial |
|
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. Conclusions
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.
Appendix B-3
Guidelines on the Use of Alternative Computer Models in Air Quality Assessment
[The information contained in this Appendix is only meant to assist the Applicant in performing the air quality assessment. The Applicant must exercise professional judgment in applying this general information for the Project.]
1. Background
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).
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.
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.
----------------------------------------------------------------------------------------------------------------------------
Schedule 1
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
* * EPD is continually reviewing the latest development in air quality models and will update this Schedule accordingly.