Based on the findings assembled in Step 4, environmental constraints, issues, opportunities as well as their linkages should be identified and examined, providing inputs to the next step where appropriate. In the identification and examination process, both the characteristics of impact generators and impacts receivers should be taken into account. For instance, in RDS2, the impact generators (i.e. railway networks’ and developments’ characteristics) and the impact receivers (i.e. the characteristics on environment and sensitive land uses) should be fully considered.

+ Example - Hong Kong 2030: Planning Vision and Strategy (HK2030)

https://www.pland.gov.hk/pland_en/p_study/comp_s/hk2030plus/index.htm

During the Study, the following environmental constraints and their possible opportunities were identified and examined in a systematic manner:

Environm-ental Issue	Constraints	Possible Opportunities
Noise	Traffic noise due to increasing transportation pressure between Hong Kong and the Mainland Industrial/Residential interface problem	Comprehensive urban renewal Requirement for thick glazing, lockable windows and split air-conditioning system Noise control at source through the incorporation of new technologies and engineering design
Air	Air movement restricted within many urban areas due to high-rise buildings Trans-boundary air pollution (click to enlarge) Figure 10 - Confined Airsheds identified in HK 2030 : Planning Vision and Strategy	Cleaner technology, cleaner fuels Better integration of environmental protection into transport and energy policies and planning
Water Quality	The pollution discharges from HK’s neighbouring area The increasing urban population within the Guangdong Province (click to enlarge) Figure 11 - Territorial Water Quality Constraints identified in HK 2030 : Planning Vision and Strategy	Underground and cavern options for possible future sewage treatment plants Cooperation with Mainland authorities in avoiding water pollution from new major developments
Waste	Inadequate landfill sites	Reuse and recycling of materials required, e.g. via integrated waste management facilities
Energy and Natural Resources	Space for facilities for generation of wind energy, biomass, wave or hydroelectric power is a major constraint when identifying viable options for Hong Kong	Use of renewable energy Enhancing the energy performance or efficiency of buildings
Greenhouse Gas	Changes to seasonal ambient temperature, ambient CO2 and alterations to rainfall patterns and intensity may put pressure on some of Hong Kong’s native species, reducing the ecosystem’s ability to respond to the predicted environmental changes	All opportunities to maintain biodiversity, increase vegetated areas and minimise the release of greenhouse gases must be considered
Risk	The existing Potential Hazardous Installations (PHIs) and certain other potentially hazardous linear infrastructure, act as a constraint in terms of the location of future development	Cost effective risk mitigation measures, e.g.:     reduction of hazardous material inventories;     provision of plant safety systems;     control of residential development near PHIs;     PHI relocation from urban sites to sites in less populated areas.

Besides, the following environmentally sensitive areas were identified and examined:

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Site of Special Scientific Interest

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Country Parks

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Marine Parks

Figure 12 - Environmentally sensitive areas identified in HK 2030 : Planning Vision and Strategy