Virtual Tutorial

Welcome to the EIA e-learning platform. I will be happy to assist you to understand more about impact analysis in the EIA report.

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Baseline information forms the foundation of an EIA, resembling piling of a building. A good baseline study enables potential impacts from a project to be predicted and evaluated. Where necessary, a baseline survey shall be carried out to determine the existing environmental conditions on the site. Let me give you some tips about the baseline data collection and survey for an EIA study.

• site constraints
• site conditions,
• location and status of sensitive receivers etc.

A good planning is needed for baseline survey which might sometime be resource demanding.

Baseline surveys shall normally include the site of the project, its access, and any other areas likely to be impacted during construction and operation (or decommissioning).

The type and duration of baseline surveys shall be such that there will be adequate information taking account of natural variation to define the existing conditions.

Annex 13 of the Technical Memorandum on the EIA Process (EIAO-TM) delineate uses that are classified as noise sensitive uses.

Some typical Noise Sensitive Receivers (NSR) are:*

	NSR
Domestic premises & temporary housing	**
Hostel	**
Hospital, clinic & nursery	**
School, educational institution	**

* within 300m of the Study Area
**Relevant standards in the Technical Memorandum apply to the uses
rely on opened windows for ventilation only.

Annex 12 of the EIAO-TM sets out the definition of air sensitive receivers (ASRs). Some typical ASRs are summarized as follows*:

	ASR
Domestic premises & temporary housing
Hotel & hostel
Hospital, clinic & nursery
School & education institution
Office, factory, shop & shopping centre
Place of worship, library & court of law
Sport stadium & performing arts centre

The aquatic system and beneficial uses sensitive to water pollution have been specified in Annex 14 of the EIAO-TM.

In general, these include:

• Water Intakes
• Beaches
• Water Recreation Areas
• Fish Culture Zones
• Marine Parks/ Reserves
• Areas of Ecological Value
• Water Gathering Grounds
• Inland Water for Agriculture and Recreational Use
• Embayed Waters like Typhoon Shelter, Marina and Boat Yard
• Coastal Protection Area
• Wild Animal Protection Area
• Fisheries Nursery and Spawning Grounds

Annex 16 of the EIAO-TM lists out the definition of "Recognized Sites of Conservation Importance", "Important Habitats Where an Ecological Assessment will be Necessary", and "Species of Conservation Importance".

There is also an EIAO Guidance Note No.7/2002 issued by EPD about the ecological baseline survey for ecological assessment.

• Study Area - normally 500m from the site boundary or the area likely to be impacted by the project;
• Review existing information;
• Identify information gaps;
• Areas of ecological interest identified in the review may subject to more detail survey; and
• Duration of ecological baseline surveys ranging from 4-month to 12-month depends on habitat sensitivity and species diversity.

To obtain good results, ecological baseline survey should be carried out at the time of the year when target group is more active, conspicuous or easy to be identified.

Yes, certainly. Once the baseline conditions have been established, the next stage will be a detailed assessment undertaken to forecast the characteristics of the main potential impacts of the project and to determine their significance.

Remember, impact prediction can be a technical exercise. Different techniques ranging from simple qualitative description to advanced mathematical modeling can be used for impact predication. Let's see what you want to know more.

Annex 5 and Annex 13 of the EIAO-TM list down the criteria and guidelines respectively for noise assessment

• Identify noise sources
• Identify noise sensitive receivers
• Quantify noise impacts (modelling or measurement)
• Mitigation measures
• Consideration of residual impacts

EPD has produced an Educational Package on Environmental Noise and is available on the EPD website. Please click here to learn more about noise assessment

The assessment criteria and guidelines have been listed down in the EIAO TM Annexes 4 and 12. There are also guidelines issued by EPD about the assessment of air quality impacts using different models, they are:

• Guidelines on Choice of Models and Model Parameters;
  
• Guidelines on Assessing the 'TOTAL' Air Quality Impacts;
  
• Guidelines on the Use of Alternative Computer Models in Air Quality Assessment; and
  
• Guidelines on Estimating Height Restriction and Position of Fresh Air Intake using Gaussian Plume Models.

These guidelines are available in the EPD website. Please click here.

• Identify air pollution sources
• Identify air sensitive receivers
• Quantify air quality impacts by modeling
• Mitigation measures

Different types of air quality model would be used to assess the impacts from different sources. Please refer to the following table:

Typical Information required for air quality assessment (Modelling Input)

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As stated in the EIAO-TM Annex 12, the presentation of assessment results should be assisted by a summary table and contour plots of pollution concentration. And the assessment results should be compared with the specified air quality standards where appropriate.

Hourly TSP Concentration

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The assessment criteria and guideline have been listed down in the EIAO-TM Annexes 6 and 14.

• Scope water bodies in spatial and temporal extent, according to direct, indirect, near filed and far filed; and cumulative impacts of the Project;
  
• Identify pollution sources
  
• Identify water sensitive receivers
  
• Assess water quality impact
  
• Define mitigation measures
  
• Assess residual impact

Quantifying Water Quality Impact

• Water Quality Model
  • Near Field - sewage/thermal, outfall initial dilution
  • Hydrodynamic - tidal flow modelling (currents and water levels)
  • Plume - sediment, bacterial, thermal
  • Water Quality - range of water quality parameters, establish pollution loading inventory
• Alternative Method
• Desktop mathematical calculation - suitable for assessing small dredging works by calculating depth averaged suspended sediment concentrations as a function of distance from works.

Some Tips......

• Significant water quality concerns cannot be concluded by qualitative assessment
• Required by EIAO Study Brief(EIAO-TM Annexes 6 and 14)
• Potential for adverse water quality impacts
• Proximity to sensitive receivers
• Usually for discreet, quantifiable pollution sources
• Discharges exceeding the TM limits for Effluents
• Discharges into Drainage and Sewerage Systems Inland and Coastal Waters

• Land based construction activities - controlled through specification of suitable control measures
• Very small scale cable laying - small scale sediment disturbance, sediment disturbance close to sea bed
• Very small scale dredging/reclamation works - subjective decision on not to model

Annexes 8 and 16 of the EIAO-TM set down the important habitats, criteria for evaluating ecological impact and guidelines for the assessments.

There are also guidance notes issued by EPD (EIAO GN 6/2002 and GN 7/2002) about ecological assessment.

Types of Ecological Impacts

Impacts due to a project are generally include:

• Habitat loss; and
• Loss of individuals of species.

• Isolation and fragmentation;
• Change of hydrology;
• Disturbance (i.e. noise, human activity);
• Impacts to water quality/discharge (SS, DO, nutrients); and
• Temporary and Permanent Loss.

• Size of the Study Area;
• Nature of the project;
• Structural complexity of the Study Area;
• Availability of the ecological information within the Study Area;
• Ecological sensitivity of the Study Area; and
• Presence of important habitats or species, particularly those with distinct seasonal variation.

OK. Mitigation is certainly a creative and practical part of the EIA process. As the rule of thumb, the mitigation measures are identified to avoid, minimize or remedy environmental impacts. What impact mitigation measures would you like to discuss more?

Annex 13 of the EIAO TM puts up a list of mitigation measures in the event of noise exceedance are predicted.

Please click here for the Educational Package on Environmental Noise to learn more about noise mitigation.

Typical Construction Dust Control Measures

Covering dusty load with tarpaulin sheet

Watering on haul road

Automatic wheel washing facility

Stockpile covering by tarpaulin sheet

Compaction and hydroseeding

• Adjust the vertical/horizontal alignment of the roadway
  
• Redesign the ventilation building and tunnel ventilation
  
• Tighten vehicle emission standards

• Redesign the process
• Siting of the facilities
• Covering major odour sources, provision of odour removal facilities, application of chemical dosing, oxygen injection

• Water conservation, effluent reuse
• Improve quality of effluent by anchoring treatment levels
• Re-site outfall
• Redesign diffusers for greater initial dilution
• Advance extension of outfall from embayed water (reclamation construction)
• Suppress foam formation (thermal discharge)
• Use suitable aeration devices to oxygenate the treated effluent
• Use environmentally friendly chemicals for water, wastewater and cooling water treatment

• Re-sequence works to avoid overlapping between concurrent activities
• Reduce dredging rate
• Use alternative dredging methods, e.g. grab dredging vs trailer dredging
• Reduce filling rate
• Use alternative filling method
• Use silt curtains/screens
• Avoid dredging, particularly contaminated sediment (leave marine sediment in-situ)
• Use close grab dredger

Reclamation phasing to minimise suspended sediments

Silt Curtain installed for and during dredging

Dredging in Motion

The general policy for mitigating impacts on important and sensitive ecological resources, as per Annex 16 of the EIAO-TM, are in the following descending order of priority:

• Avoidance
• Minimisation
• Compensation

From an ecological point of view, mitigation measures for ecological impact shall preferably be carried out on-site and well in advance of the works, rather than off-site and after the completion of works.

You are welcome. I hope you have a better understanding of your EIA report.