Impact Identification and Evaluation
Impact Identification and Evaluation
Impact assessment links project activities to environmental change, evaluates the consequences for receptors and explains the basis for each significance conclusion.
## 1. Identify impacts systematically Review each project phase—site preparation, construction, commissioning, operation, maintenance, decommissioning—and each activity or abnormal event. Trace the source, pathway and receptor.
## 2. Common impact pathways | Project activity | Source / pressure | Potential receptor or effect | |—|—|—| | Industrial combustion | Stack emissions | Ambient air quality and human health | | Chemical storage | Leak or spill | Soil, groundwater and surface water | | Wastewater discharge | Effluent load and temperature | Receiving-water quality and ecology | | Sludge handling | Odour, leakage and transport | Nearby communities, soil and water | | Water abstraction | Reduced flow or groundwater drawdown | Aquatic ecology and other users | | Construction | Dust, noise, runoff and traffic | Neighbours, roads and habitats |
## 3. Evaluate significance transparently Consider: - Magnitude: intensity, concentration, area, duration and reversibility of change. - Receptor sensitivity: ecological, social, health or resource importance. - Likelihood: probability of occurrence, where relevant. - Extent and duration: local or regional; temporary, intermittent or long-term. - Cumulative context: interaction with existing and reasonably foreseeable activities.
A matrix may support consistency, but it must not replace professional reasoning. Define scoring terms before applying them and explain uncertainty and assumptions.
## 4. Separate impact types Assess direct, indirect, induced, cumulative and residual impacts. Consider routine operation as well as credible abnormal conditions and emergencies.
## 5. Impact register | Activity | Impact pathway | Receptor | Initial significance | Mitigation | Residual significance | |—|—|—|—|—|—| | Illustrative activity | Source → pathway | Receptor | To be assessed | Defined measure | Reassess after mitigation |
## 6. Avoid false precision Do not label an impact significant or compliant solely because one measurement is below a limit. Compare results with the applicable criteria, baseline, receptor sensitivity, exposure pathway and assessment objectives.