1. BACKGROUND

1.1 An application (No. ESB-090/2001) 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 15 November 2001 with a Project Profile (No. PP-152/2001) for the captioned project.

1.2 The proposed project is to convert the existing Hang Hau Tsuen stream into an engineered channel between Deep Bay and Deep Bay Road. The proposed project will include the construction of a 380m trapezoidal channel (with 6m wide channel base and approximately overall width of 25m) and a 25m long twin box culvert beneath the Deep Bay Road and associated footbridges and footpath works. The proposed project might cause potential impacts on the drainage and hydrology of the surrounding habitats, like stream meander, mangrove and inter-tidal mudflats within or near to Hang Hau Tsuen stream.

1.3 The Applicant has identified a potential alignment for the Hang Hau Tsuen Channel. (as shown in Figure 1 attached). The proposed drainage works start at the twin box culvert underneath Deep Bay Road. The project is a Designated Project under Schedule 2, Part I I.1(b) of the EIAO and requires an environmental permit under the EIAO for its construction and operation.

1.4 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.

1.5 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 proposed project 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 as a result of the proposed project;

(ii) the conditions and requirements for the detailed design, construction and operation of the proposed 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 proposed project and associated works together with the requirements for carrying out the proposed project;

(ii) to identify and describe the elements of the community and environment likely to be affected by the proposed project and/or likely to cause adverse impacts to the proposed project, including both the natural and man-made environment;

(iii) to identify and quantify emission sources and determine the significance of impacts on sensitive receivers and potential affected uses;

(iv) to identify any potential impacts from point and non-point pollution sources on the identified water systems and sensitive receivers during the construction and operation stages;

(v) to identify and quantify any potential losses and damage to flora, fauna and wildlife habitats;

(vi) to identify and quantify, where applicable, any potential landscape and visual impacts and determine the significance of impacts on sensitive receivers;

(vii) to identify any potential impacts to the historical, archaeological and cultural resources and propose measures to mitigate these impacts;

(viii) to propose the provision of infrastructure or mitigation measures so as to minimize pollution, environmental disturbance and nuisance during construction and operation of the proposed project;

(ix) to identify, predict and evaluate the residual (i.e. after practicable mitigation) environmental impacts and the cumulative effects expected to arise during the construction and operation phases of the proposed project in relation to the sensitive receivers and potential affected uses;

(x) to identify, assess and specify methods, measures and standards, to be included in the detailed design, construction and operation of the proposed project, which are necessary to mitigate these environmental impacts and reducing them to acceptable levels;

(xi) to investigate the extent of 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;

(xii) to design and specify the environmental monitoring and audit requirements, if required, to ensure the implementation and the effectiveness of the environmental protection and pollution control measures adopted; and

(xiii) to consider alternatives with a view to avoid or minimize the potential environmental impacts on but not limited to (a) area(s) of conservation interest such as Hang Hau Tsuen stream, the Coastal Protection Area (CPA) near to the Hang Hau Tsuen, the mangrove, fishponds and inter-tidal mudflats and the Inner Deep Bay; and (b) the site(s) of cultural heritage and other sensitive uses; and to compare the environmental benefits and dis-benefits of each of the different options and to provide reasons for selecting the preferred option(s) and to describe the part environmental factors played in the selection.

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 EIA Process of the EIAO (hereinafter referred to as the TM) are fully complied with.

3.2 The Scope

The scope of this EIA study covers the proposed project mentioned in section 1.2 above. The EIA study shall address the likely key issues described below; together with any key issues identified during the course of the EIA study.

(i) the potential impacts on the Hang Hau Tsuen stream and the Coastal Protection Area near to the Hang Hau Tsuen stream, in particular, the assessment shall include but not limited to the stream course, the stream meander, mangrove and inter-tidal mudflats and remaining fishponds within or near to the Hang Hau Tsuen stream;

(ii) the potential noise, dust and odour impacts to sensitive receivers during the construction phase, in particular at areas near to school(s), village houses and other residential quarters/dwellings;

(iii) the potential aquatic and terrestrial ecological impacts arising from the construction works, including loss of habitats, removal of vegetation and disturbance to plants and animals. The assessment shall fully address all direct, indirect and cumulative impacts resulting from the proposed project on the integrity and viability of the ecosystems of the Hang Hau Tsuen stream and Inner Deep Bay;

(iv) the potential impacts on the drainage and hydrology, water quality and aquatic ecology of the Hang Hau Tsuen stream floodplain from the proposed project, in particular the potential impacts on the flow regime, water level and water quality on the stream meanders, mangrove and inter-tidal mudflat habitats in the study area;

(v) the potential impacts on the flow regime and water quality of the study area and Inner Deep Bay during the construction and operation phases;

(vi) the potential landscape and visual impacts arising from the removal of stream meanders, vegetation cover, mangroves and mudflats and the cutting of bank(s) along channel sides and any impact on visually sensitive receivers. In addition, appropriate landscape treatment shall also be provided to mitigate the landscape and visual impacts of the project; and

(vii) the potential impacts on the cultural heritage sites, in particular on the Hang Hau Tsuen Archaeological Site, the Sha Kong Miu Archaeological Site and the sand dune and kiln remains north of Hang Hau Tsuen, if they are affected by the construction works of the proposed project.

3.3 Consideration of the Need of the Project, Alternative Drainage Options and Alignments, Channel Designs and Construction Methods

3.3.1 The Need of Project, Alternative Drainage Options, Channel Alignments and Designs

The Applicant shall study and review the need of the proposed project. Information/proof to justify the need and scale of the Hang Hau Tsuen stream channelisation works is required. The Applicant shall provide information, including the floodplain hydraulics and hydrological predictions (with/without other drainage channels in place) to justify the need and function of the proposed project.

In addition, consideration of alternaives to alleviate flooding in the area shall be considered in the EIA, these shall include, among other things, different flood alleviation options such as dredging and removing bottom mud and sediments from the stream while preserving the natural meandering of the Hang Hau Tsuen stream, alternative channel alignments, alternative channel lining (including the use of unlined channel bed, rip rap based channel and other possible environmental friendly designs) shall be discussed and assessed. In considering the alternative flood alleviation options and channel alignments/lining designs, consideration shall be given to minimizing the negative effect on the Hang Hau Tsuen stream course, the mangrove colony and nearby fishpond habitats and the inter-tidal mudflats.

An evaluation system shall be set up to assess the environmental benefits and dis-benefits of all possible flood alleviation options and channel development options. The potential ecological impacts on the habitats identified above are key issues to the evaluation system. The final recommended flood alleviation option(s), channel alignment/lining option(s) should be well assessed and justified especially on whether the option(s) will affect the habitats identified above.

3.3.2 Consideration of Alternative Construction Methods and Sequences of Works

Having regard to the cumulative effects of the construction period and the severity of the construction impacts to the affected sensitive receivers along the drainage channel, the EIA study shall also explore alternative construction methods and sequences of works for the proposed project with a view to avoid adverse environmental impacts to the maximum practicable extent. A comparison of the environmental benefits and dis-benefits of applying different construction methods shall be made. The Applicant shall take into account of the environmental implications of possible release of heavy metals from mud during the excavation works and potential water quality impacts during the construction phase.

3.3.3 Taking into the comparison in sections 3.3.1 and 3.3.2 above, the Applicant shall recommend/justify the adoption of the flood alleviation option(s) and recommeded channel development option, channel alignment and lining design that will avoid or minimise adverse environmental effects, in particular the ecological impacts on habitats identified above.

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 above and subject to the findings under section 3.3. The EIA study shall include the following technical requirements on specific impacts.

3.4.1 Construction Air Quality Impacts

3.4.1.1 The Applicant shall follow the criteria and guidelines for evaluating and assessing construction air quality impact as stated in section 1 of Annex 4 and Annex 12 of the TM respectively.

3.4.1.2 The assessment area for the construction air quality impact assessment shall generally be defined by a distance of 500 m from the boundary of the proposed project works sites, yet it may be extended depending on the circumstances and the scale of the project.

3.4.1.3 The Applicant shall assess the air pollutant concentrations with reference to the relevant sections of the guidelines attached with this study brief in Appendices A-I to A-III, or other methodology as agreed by the Director.

3.4.1.4 The air quality assessment shall include the following:

Background and Analysis of Activities

(i) Provide background information relating to air quality issues relevant to the project, e.g. description of the types of activities of the project.

(ii) 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 to minimize the constructional air quality impact, e.g. use of marine access routes for transportation of construction materials to avoid dust impact on air sensitive receivers due to haul road transport during construction.

(iii) Present the background air quality levels in the assessment area for the purpose of evaluating the cumulative constructional air quality impacts.

Identification of Air Sensitive Receivers (ASRs) and examination of emission/dispersion characteristics

(iv) Identify and describe representative existing and planned/committed ASRs that would likely be affected by the project. The Applicant shall select the assessment points of the identified ASRs such that they represent the worst impact point on 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.

(v) Provide an exhaustive list of air pollutant emission sources, including any nearby emission sources, which are likely to have impact on the project. Examples of construction stage emission sources include stockpiling, blasting, concrete batching and vehicular movements on unpaved haul roads on site, odour from mud excavation works and so forth. Confirmation of the validity of the assumptions and the magnitude of the activities (e.g. volume of construction materials handled) shall be obtained from the relevant government/authorities and documented.

Impact Assessment

(vi) The Applicant shall carry quantitative assessment to evaluate the construction dust impact at the identified ASRs and to ensure construction dust impacts are controlled to within the relevant standards as stipulated in Annex 4 of the TM. A monitoring and audit program during the construction stage shall be implemented to verify the effectiveness of the control measures and to ensure that the construction dust levels are brought under control.

(vii) The Applicant shall follow the methodology below when carrying out the assessment.

Quantitative Assessment Methodology

(viii) The Applicant shall apply the general principles enunciated in the modeling guidelines while making allowance for the specific characteristics of each project. Specific methodology must be documented to such level of detail (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 for input to the modeling shall be presented in the EIA 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 of the general methodology between the Applicant and the Director is advised.

(ix) The Applicant shall identify the key/representative air pollutant parameters related to construction activities (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 proposed project.

(x) 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 tables and pollution contours, for comparison with relevant air quality standards and for examination of the land use implications of these impacts. Plans of suitable scale should be used for presentation of pollution contours for determining buffer distances required.

Mitigating Measures for Non-compliance

(xi) 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 proposed mitigating measures will comply with the criteria stipulated in section 1 of Annex 4 in the TM.

Submission of Model Files

(xii) All input and output file(s) of the model run(s) shall be submitted to the Director in electronic format.

3.4.2 Construction Noise Impact

3.4.2.1 The Applicant shall follow the criteria and guidelines for evaluating and assessing construction noise impact as stated in Annexes 5 and 13 of the TM, respectively.

3.4.2.2 The construction noise impact assessment shall include the following:

(i) Determination of Assessment Area

The "Assessment Area" for the construction noise impact assessment shall include all areas within 300 m from the project boundary. Subject to the agreement of the Director, the assessment area could be reduced accordingly if the first layer of noise sensitive receivers, closer than 300 m from the project boundary, provides acoustic shielding to those receivers further from the site.

(ii) Provision of Background Information and Existing Noise Levels

The Applicant shall provide all background information relevant to the project, including relevant previous or current studies. Unless necessary for planning standards, it will not be necessary to investigate the existing noise levels.

(iii) Identification of Noise Sensitive Receivers

(a) The Applicant shall refer to Annex 13 of the TM when identifying the noise sensitive receivers (NSRs). The NSRs shall include all existing NSRs and all planned/committed noise sensitive developments and uses earmarked on the relevant Outline Zoning Plans, Outline Development Plans, Layout Plans and other published plans, including any land use and development applications approved by Town Planning Board. For planned noise sensitive land uses without committed layouts, the Applicant shall work out indicative site layouts based on the relevant planning parameters.

(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 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 including construction equipment for construction noise assessment. Confirmation of the validity of the inventory shall be obtained from the relevant government departments/authorities.

(v) Construction Noise Assessment

(a) The Applicant shall carry out assessment of noise impact from construction (excluding percussive piling) of each designated 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 criteria in Table 1B of Annex 5 of the TM shall be adopted in the assessment.

(b) To minimize the construction noise impact, alternative construction methods to replace percussive piling shall be explored and recommended as far as practicable.

(c) If the unmitigated construction 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 task) to minimize the impact. If the mitigated noise levels still exceed the relevant criteria, the duration of the noise exceedance shall be given.

(d) The applicant shall confirm whether construction work during restricted hours is required. If affirmative, the applicant shall evaluate whether construction works in restricted hours as defined under the Noise Control Ordinance (NCO) are feasible or not in the context of programming construction works. Reference shall be made to the relevant technical memoranda issued under the NCO. Regardless of the results of the construction noise impact assessment for restricted hours, the Noise Control Authority will process the 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 should be explicitly stated in the noise chapter and the conclusions and recommendations chapter in the EIA report.

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 assessment area for the water quality impact assessment shall include all areas within 500m from the project boundary, the area shall include but not limited to the Hang Hau Tsuen stream catchment and Inner Deep Bay. This assessment area could be extended to include other areas such as stream courses and the associated water system in the vicinity being impacted during the course of the EIA study if found justifiable.

3.4.3.3 The Applicant shall identify and analyze all physical, chemical and biological disruptions of marine, fresh water or ground water system(s), catchment area(s), storm water channel and coastal water arising from the construction and operation of the designated projects.

3.4.3.4 The Applicant shall include (1) the construction phase impacts on water quality at the site; and (2) the operational phase impacts on water quality downstream of the site due to the natural process of siltation, flows and water velocity, and re-suspensions of sediments. Essentially, the assessment shall address the following:

(i) Collection and review of background information on the existing and planned water systems and their respective catchments and sensitive receivers which might be affected by the project during construction and operation;

(ii) Characterization of water and sediment quality of the water systems and respective catchments and sensitive receivers which might be affected by the project during construction and operation based on existing information or appropriate site survey and tests;

(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. The Applicant shall refer to, inter alia, those developments and uses earmarked on the relevant Outline Zoning Plans, Outline Development Plans and Layout Plans;

(iv) Identification of pertinent water and sediment quality objectives and establishment of other appropriate water and sediment quality criteria or standards for the water system(s) and all the sensitive receivers in (i) above;

(v) Review the specific construction methods and configurations, and operation of the project (including the proposed access road and footpaths). Identification of any alteration of existing water courses, meander, natural streams/ponds, shoreline or bathymetry, flow regimes, ground water levels and catchment types or areas;

(vi) Identification, analysis and quantification of all existing, likely future water and sediment pollution sources, including point discharges and non-point sources to surface water runoff and analyze these in relation to the provision and adequacy of future facilities to reduce such pollution in terms of capacity and levels of treatment; evaluation and quantification through appropriate site investigation and tests to the pollution loading intercepted by the project and discharged into the Inner Deep Bay; evaluation and quantification of the flows and pollution loads collected and discharged into the existing and planned downstream water courses and drainage systems before and after operation of the project;

(vii) Establishment and provision of a pollution load inventory on the quantities and characteristics of all existing and likely future water pollution sources identified above. Field investigation and laboratory tests shall be conducted as appropriate to fill in any major information gaps;

(viii) Cumulative impacts due to all other committed and planned projects (in particular due to the Shenzhen Western Corridor project) and activities or pollution sources in the Lau Fau Shan Area along the identified water system(s) and sensitive receivers shall be identified and assessed through undertaking a hydraulic modelling;

(ix) Assessment and evaluation of any potential water quality impacts on the identified water system(s), respective catchments and sensitive receivers due to sewage arising from the construction stage. Any effluent generated will require appropriate collection, treatment and disposal to within standards and objectives and criteria established in (iv) above;

(x) Assessment and evaluation of any potential storm water and construction runoff impacts on the water system(s), respective catchments and sensitive receivers during construction stages as to reduce the water and sediment quality impacts to within standards, objectives and criteria established in (iv) above. Best management practices shall be recommended to reduce any potential impacts arising from storm water runoff during both construction and operation phases;

(xi) Establishment of the erosion control plan during construction as per assessment carried out in point (x) above. This erosion control plan shall incorporate details such as locations, sizes and types of best management practices, which will be used to reduce storm water pollution arising from construction works;

(xii) Should dredging be required, the Applicant shall evaluate and quantify the possible impacts arising from the dredging works. The Applicant shall identify clearly the nature, extent and rate of the dredging works, and the volume of sediment disturbed. Appropriate laboratory tests such as elutriate tests (USACE) and sediment pore water (interstitial water) analyses shall be performed on the sediment samples to simulate and quantify the degree of mobilization of various contaminants such as metals, ammonia, trace organic contaminants such as PCBs, PAHs, TBT and chlorinated pesticides into the water column during dredging. Identification and quantification of all dredging, fill extraction, filling, mud/sediment transportation and disposal activities and requirements. Potential fill source and dumping ground to be involved shall also be identified. Field investigation, sampling and chemical and biological laboratory tests to characterize the sediment/mud concerned shall be conducted as appropriate. The ranges of parameters to be analysed; the number, type and methods of sampling; sample preservation; chemical and biological laboratory test method; and the laboratory to be used shall be subject to the approval of the Director. Any seriously contaminated sediment which requires special treatment and/or disposal arrangement in accordance with WBTC No.3/2000 shall be identified by both chemical and biological tests. If the presence of such sediment is confirmed, the Applicant shall identify the most appropriate treatment and/or disposal arrangement and demonstrate its feasibility. Identification and evaluation of the best practicable dredging methods to minimize dredging and dumping requirements and demand for fill sources based on the criterion that existing marine mud shall be left in place and not to be disturbed as far as possible.

(xiii) In case of small scale dredging works and with the prior written approval by the Director, the Applicant shall assess the potential increase in turbidity and suspended solids levels in the water column due to disturbance of marine sediments during dredging. The potential for release of contaminants during dredging shall also be addressed using the chemical testing results derived from sediment samples collected on site and relevant historic data;

(xiv) The Applicant shall identify whether the discharge of runoff into Inner Deep Bay during the operation phases will give rise to adverse impacts on water quality in accordance with the TM. The Applicant shall evaluate any water quality impacts, including changes in sediment erosion or deposition pattern, downstream salinity profile and effect on aquatic organisms. This assessment shall have regard for the frequency, duration, volume and flow rate of the discharge and its pollutant and sediment load;

Waste Water and Non-point Sources Pollution

(xv) Proposals for effective and practicable infrastructure upgrading or provision, water pollution prevention and mitigation measures to be implemented during the construction and operation stages 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;

(xvi) Best management practices to reduce storm water and non-point source pollution shall be investigated and proposed as appropriate;

(xvii) 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.

Protection Against Accidental Spillage

(xix) Specification of an emergency contingency plan for the construction and operation phase of the proposed project to contain and remove all accidental spillage along the channel, the access road(s)/haul road(s) at short notice and to prevent or to minimize the quantities of contaminants from the stream water and sensitive habitats.

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

Identification of the quantity, quality and timing of the waste arising as a result of the construction and operation activities, 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 and on-site or off-site re-use 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 the result of the assessment in (c) below; and

(c) The impact caused by handling (including labeling, packaging & storage), collection, and disposal of wastes shall be addressed in detail and appropriate mitigation measures proposed. This assessment shall cover the following areas:

- potential hazard;
- air and odour emissions;
- noise;
- wastewater discharge; and
- public transport.

(iii) Land Contamination Assessment:

(a) Identify whether land lots/sites and sediment of the Hang Hau Tsuen stream within the study area boundary, which due to their past or present land uses, are potential contaminated. A detailed account of the present activities and past land history in relation to possible land contamination should be provided. The assessment shall pay attention to the potential release of the contaminants into the environment and cause further pollution problems in Deep Bay during excavation works especially during wet seasons;

(b) The list of potential contaminants which are anticipated to be found in these potential contaminated sites should be provided and the possible remediation options should be discussed;

(c) To evaluate the effectiveness of the recommended excavation method(s) of sediment so as to ensure the contaminants from the sediments would not be released into the environment; and

(d) The evaluate the control of on-site contamination would be properly treated and disposed of.

3.4.5 Ecological Impact (Both Terrestrial and Aquatic)

3.4.5.1 The Applicant shall follow the criteria and guidelines for evaluating and assessing ecological impact as stated in Annexes 8 and 16 of the TM, respectively. The assessment area for the purpose of terrestrial ecological assessment shall include all areas within 500 m distance from the site boundary of the works areas, or the area likely to be impacted by the designated projects. For aquatic ecology, the assessment area shall be the same as for water quality assessment described in Section 3.4.3.2.

3.4.5.2 In the ecological impact assessment, the Applicant shall examine the flora, fauna and other components of the ecological habitats within the assessment area. The aim shall be to protect, maintain or rehabilitate the natural environment. The assessment shall identify and quantify as far as possible the potential ecological impacts associated with the project, including the impacts of any haul roads and temporary access. The potential impact on water quality and aquatic ecology from the discharge of storm water into Inner Deep Bay waters during the operational phase shall also be addressed.

3.4.5.3 The assessment shall include the following:

(i) A review of the findings of relevant studies and collating all the available information regarding the ecological characters of the assessment area;

(ii) Evaluation of the information collected and identification of any information gap relating to the assessment of potential ecological impacts to the terrestrial and aquatic environment;

(iii) Carrying out the necessary field surveys (the duration of which shall be at least 6 months covering bird migratory period in winter) and investigations to verify the information collected, fill the information gaps identified and fulfil the objectives of the EIA study;

(iv) Establishing the general ecological profile and describing the characteristics of each habitat found; major information to be provided shall include:

(a) Description of the physical environment;

(b) Preparation of habitat maps of suitable scale (1:1000 to 1:5000) showing the types and locations of habitats in the assessment area;

(c) Definition and characterization of the ecological characteristics of each habitat type including size, vegetation type, species present, dominant species found, species diversity and abundance, community structure, seasonality and inter-dependence of the habitats and species, and presence of any features of ecological importance;

(d) Presentation of representative colour photos of each habitat type and of any important ecological features identified;

(e) Listing of species found that are rare, endangered and/or listed under local legislation, international conventions for conservation of wildlife/habitats or red data books;

(v) Investigation and description of the existing wildlife uses of various habitats with special attention to those wildlife groups and habitats with conservation interest including:

(a) the Coastal Protection Area near Hang Hau Tsuen;
(b) natural stream courses and meanders of Hang Hau Tsuen stream;
(c) fishponds, inter-tidal mudflats and mangrove at or near the project area;
(d) avifauna in particular waterdirds (representative data during the winter migratory bird season shall be provided); and
(e) any other habitats and wildlife groups identified as having special conservation interests by the study.

(vi) Description of all recognized sites of conservation importance in the proposed development site and its vicinity and assessment of whether these sites will be affected by the proposed development or not;

(vii) Using suitable methodology, identification and quantification as far as possible of any direct, indirect, on-site, off-site, primary, secondary and cumulative ecological impacts such as destruction of habitats, reduction of species abundance/diversity, loss of feeding, nesting or/and breeding grounds, reduction of ecological carrying capacity, habitat fragmentation; and in particular the following;

(a) ecological impacts of potential loss of areas of conservation interest such as natural stream courses, fishponds, inter-tidal mudflats and mangrove;
(b) disturbance to wildlife during construction stage in particular the impacts on waterbirds;
(c) impacts due to the potential sedimentation to the inter-tidal mudflats and Deep Bay during construction stage;
(d) operational impacts on aquatic life and other wildlife in Deep Bay through periodic storm discharges at the portal; and
(e) cumulative impacts due to other planned and committed development projects at or near the project area.

If off-site mitigation is considered necessary to mitigate the environmental impact, the guidelines and requirements laid down in Annex 16 of the TM should be followed.

(viii) Evaluation of the significance and acceptability of the ecological impacts identified using well-defined criteria;

(ix) Recommendations for all possible alternatives, such as modifications of channel alignment, layout and design and practicable mitigation measures to avoid, minimize and/or compensate for the adverse ecological impacts identified, such as reinstatement of habitats temporarily affected by the proposed development to its original state and if possible with some enhancement features, the mitigation measures shall include, but not limited to, on site and/or off-site wetland compensation. In particular, the assessment shall evaluate the potential positive/negative ecological impacts of planting mangroves along the shore between Lau Fau Shan and Pak Nai. Special attention shall be paid on the fact that this would diminish the feeding grounds for the waterdirds to feed, in particular, the potential existing of wintering Black-faced Spoonbills. The EIA shall propose and evaluate alternative on and off-site ecological compensation package;

(x) Evaluation of the feasibility and effectiveness of the recommended mitigation measures and definition of the scope, type, location, implementation arrangement, resources requirement, subsequent management and maintenance of such measures;

(xi) Determination and quantification as far as possible of the residual ecological impacts after implementation of the proposed mitigation measures;

(xii) Evaluation the severity and acceptability of the residual ecological impacts using well-defined criteria; and

(xiii) A review of the need for and recommendation for any ecological monitoring programme is required.

3.4.6 Landscape and Visual Impact

3.4.6.1 The Applicant shall follow the criteria and guidelines as stated in section 1 of Annex 10 and Annex 18 of the TM respectively for evaluating and assessing landscape arid visual impacts of any above ground structures and work areas associated with the proposed project. Landscape and visual impacts during both construction and operation phases within the assessment area shall be assessed.

3.4.6.2 The assessment area for landscape impact assessment shall include all areas within a 500m distance from the work limit of the proposed project while the assessment area for the visual impact assessment shall be defined by the visual envelope of the project.

3.4.6.3 The Applicant shall review relevant outline development plan(s), outline zoning plan(s) such as the Lau Fau Shan & Tsim Bei Tsui OZP and Ha Tsuen OZP, layout plan(s), other published land use plans, planning briefs and studies such as the North West New Territories (Yuen Long District) Development Statement, which may identify areas of high landscape value and recommend green belt and coastal protection area designations. Any guidelines on landscape strategy, landscape framework, urban design concept, building height profiles, designated view corridors, open space network and landscape link that may affect the appreciation of the proposed project shall also be reviewed. The aim is to gain an insight to the future outlook of the area affected so as to assess whether the project can fit into the surrounding setting. Any conflict with statutory land use plan(s) should be highlighted and appropriate follow-up action should be recommended.

3.4.6.4 The Applicant shall describe, appraise, analyze and evaluate the existing landscape resources and character of the assessment area. A system should be derived for judging landscape and visual impact significance as required under the TM. The sensitivity of the landscape framework and its ability to accommodate change shall be particularly focused on. The Applicant shall identify the degree of compatibility of the proposed project with the existing and planned landscape setting. The landscape impact assessment shall quantify the potential landscape impact as far as possible so as to illustrate the significance of such impacts arising from the proposed project. Clear mapping of the landscape impact is required. A tree survey shall be carried out and the impacts on existing mature trees shall be addressed.

3.4.6.5 The Applicant shall assess the visual impacts of the proposed project. Clear illustration including mapping of visual impact is required. The assessment shall include the following:

(i) identification and plotting of visual envelope of the proposed project within the assessment area;

(ii) identification of the key groups of sensitive receivers within the visual envelope with regard to views from both ground/sea level and elevated vantage points;

(iii) description of the visual compatibility of the project such as channel wall, and associated access road, footbridge(s)/footpath(s) with the surrounding and the planned setting, 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.

3.4.6.6 The Applicant shall evaluate the merits of preservation in totality, in parts or total destruction of existing landscape. In addition, alternative alignment, design and construction method that would avoid or reduce the landscape and visual impact shall be evaluated for comparison before adopting other mitigation or compensatory measures to alleviate the impacts. The mitigation measures proposed shall not only be concerned with damage reduction but should also include consideration of potential enhancement of existing landscape. The Applicant shall recommend mitigation measures to minimize the adverse effects identified above, including provision of a landscape design.

3.4.6.7 The mitigation measures shall also include the preservation of vegetation, transplanting of mature trees, provision of screen planting, re-vegetation of disturbed land, compensatory planting, design of structures, provision of finishes to structures, colour scheme and texture of material used and any measures to mitigate the disturbance of the existing land use. Parties shall be identified for the on going management and maintenance of the proposed mitigation works to ensure their effectiveness throughout the operation phase of the project. A practical programme and funding proposal for the implementation of the recommended measures shall be provided.

3.4.6.8 Annotated illustration materials such as coloured perspective drawings, plans and section/elevation diagrams, oblique aerial photographs, photographs taken at vantage points, and computer-generated photomontage shall be adopted to fully illustrate the landscape and visual impacts of the proposed project to the satisfaction of the Director. 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.

3.4.7 Impact on Cultural Heritage

3.4.7.1 The Applicant shall follow the criteria and guidelines for evaluating and assessing the cultural heritage impacts as stated in Annexes 10 and 19 of the TM, respectively.

3.4.7.2 The heritage impact assessment information shall include the following:

(i) The Applicant shall identify all sites of cultural heritage that might be adversely affected by the impacts due to vibration associated with the construction activities of the designated projects. The EIA study shall establish a comprehensive inventory of archaeological sites, historic buildings and structures located within or in close proximity to the designated project area that might have the potential to be affected. A plan showing the location of both the proposed works and all sites of cultural heritage identified is required. Besides, a check list including all the affected sites of cultural heritage, impacts identified, recommended mitigation measures as well as the implementation agent and period shall also be included in the EIA report.

(ii) The Applicant shall assess the extent to which those sites of cultural heritage might be directly and indirectly affected and recommend possible alternatives (such as modification of layout and design of the project) and practicable monitoring and mitigation measures to avoid or keep the adverse impacts on the site of cultural heritage to the minimum.

(iii) Special attention shall be paid to the Hang Hau Tsuen Archaeological Site, the Sha Kong Miu Archaeological Site, the sand dune and the historic kiln remains in the vicinity of the project. A map in 1:1000 scale indicating the boundary of these archaeological relics/sites, identified built heritage and declared monuments and the nearby work areas shall be provided.

3.4.8 Fisheries Impact

3.4.8.1 The Applicant shall follow the criteria and guidelines for assessing fisheries impact as specified in Annexes 9 and 17 of the TM.

3.4.8.2 The assessment area shall include 500m from the limit of the Works Area and the oyster beds in Lau Fau Shan and Inner Deep Bay.

3.4.8.3 The study shall review and collate existing information to provide adequate and accurate data for prediction and evaluation of impacts of the proposed project on fisheries. Appropriate field surveys are required to fill data gap and to gather update information for subsequent fisheries impact prediction and evaluation, formation of proposed mitigation measures and monitoring requirements.

3.4.8.4 The fisheries impact assessment shall include the following major tasks:

(i) Description of the physical environmental background;

(ii) Description and quantification of the existing fisheries activities (eg. pond culture and oyster farming);

(iii) Description and quantification of the existing fisheries resources;

(iv) Identification of parameters and areas that are important of fisheries;

(v) Identification and quantification of any direct, indirect, on-site and off-site impacts to fisheries (eg. loss of fishponds/oyster beds and temporary occupied areas);

(vi) Evaluation of impacts and proposals for any practical alternatives or mitigation measures to prevent or minimize adverse impacts on fisheries; and

(vii) A review of the need for and recommendations of any fisheries monitoring and audit programme is required.

4. ENVIRONMENTAL MONITORING & AUDIT (EM&A) REQUIREMENTS

4.1 The Applicant shall identify 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 the EM&A requirements for the project in the EIA study.

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. The Applicant shall also propose real-time reporting of monitoring data for the Project through a dedicated internet website.

4.3 The Applicant shall prepare a project implementation schedule, in the form of a checklist as shown in Appendix B attached to this study brief, containing all the EIA study recommendations and mitigation measures with reference to the implementation programme.

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 If the EIA study does not commence within 36 months after the date of issue of this study brief, 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) 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, any addendum to the EIA report and the executive summary submitted in (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.

7.3 The Applicant shall, upon request, 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 Hyper Text 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 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 up to date electronic copies.

7.7 To promote environmentally friendly and efficient dissemination of information, both hard copies 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.

8. OTHER PROCEDURAL REQUIREMENTS

8.1 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 1.2 of this EIA study brief and in the Project Profile (No. PP-152/2001), 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.

December 2001
Environmental Assessment and Noise Division
Environmental Protection Department

Appendix A-I

[The information contained in this Appendix is meant to assist the Applicant in performing the air quality assessment. The Applicant must exercise professional judgment in applying this general information for the Peroject.]

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 modeling exercises 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 model 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'.

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 A-III) 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 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 ofσΘrange 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.

3.5 Receptors

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 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

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.

3.8 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 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. Refer to EPD reference paper 'Guidelines on Assessing the 'TOTAL' Air Quality Impacts' for further information.

3.10 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.

Modelling Section, Air Policy Group
Environmental Protection Department
March 2000

Industrial Source Complex Dispersion Model ¡V 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 A-II

[The information contained in this Appendix is meant to assist the Applicant in performing the air quality assessment. The Applicant must exercise professional judgment in applying this general information for the Peroject.]

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 this constituency is the Rural/New Development category. The monitoring station suggested for the 'district-averaging'(arithmetic mean) to derive average for background air quality is 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 value for TSP in rural/new development has been obtained as follow:

POLLUTANT	RURAL/NEW DEVELOPMENT
TSP	87

The unit is in micrograms per cubic metre. The above value is derived from 1992 to 1996 annual averages.

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 value 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 value can also be used for short term assessment. This implies that the short term background value 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 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 realised) 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.

Modelling Section, Air Policy Group
Environmental Protection Department
March 2000

Appendix A-III

[The information contained in this Appendix is meant to assist the Applicant in performing the air quality assessment. The Applicant must exercise professional judgment in applying this general information for the Peroject.]

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 Schedule1models.

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.

Modelling Section, Air Policy Group
Environmental Protection Department
March 2000

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.

* EPD is continually reviewing the latest development in air quality models and will update this Schedule accordingly.