Impact Scoping and

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Lecture 7

• Impact Scoping and
• Thresholds of Significance

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Screening and scoping compared

• Screening
• determines the requirement for EIA
• establishes the level of review necessary
• Scoping
• identifies the key issues and impacts
• establishes the terms of reference

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Generalized EIA Process Regulatory Framework
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NEPA Process
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Scoping

• early step begins once screening completed
• open, interactive process involves the public
• lays the foundation of an EIA by identifying
• - boundaries of the EIA study
• - the information necessary for decision-making
• - key issues and significant impacts to be
  considered

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Key objectives of scoping

• inform and identify stakeholders
• find out stakeholder concerns
• consider feasible and practical alternatives
• identify the main issues and impacts to be
  studied
• define the boundaries of the EIA study
• agree on means of public involvement and methods
  of analysis
• establish protocols and methodologies

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The conduct of scoping

• identify range of concerns
• evaluate them to determine key issues
• categorise the impacts that require study
• establish a strategy for addressing them

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Impact identification methods

• checklists
• matrices
• networks
• overlays and geographical information systems
  (GIS)
• expert systems
• professional judgement

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Advantages and disadvantages of impact
identification methods
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An environmental impact
(Wathern, 1988)
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Methods of impact prediction

• best estimate professional judgement
• quantitative mathematical models
• experiments and physical models
• case studies as analogues or references

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Significant Effect on Environment

• a substantial, or potentially substantial,
  adverse change in any of the physical conditions
  within the area affected by the project including
  land, air, water, minerals, flora, fauna, ambient
  noise, and objects of historic or aesthetic
  significance - CEQA

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Thresholds of Significance

• That level at which the Lead Agency finds the
  effects of the project to be significant
• A quantitative or qualitative standard, or set of
  criteria, pursuant to which the significance of a
  given environmental effect may be determined

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Thresholds of Significance
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Key elements for assessing impact significance

• environmental standards
• level of public concern
• scientific and professional evidence concerning
• - resource loss/ecological damage
• - negative social impacts
• - foreclosure of land and resource use options

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Basis for Thresholds of Significance

• A health-based standard such as air pollutant
  emission standards, water pollutant discharge
  standards, or noise levels.
• Service capacity standards such as traffic level
  of service, water supply capacity, or waste
  treatment plant capacity.
• Ecological tolerance standards such as physical
  carrying capacity, impacts on declared threatened
  or endangered species, loss of prime farmland, or
  wetland encroachment.
• Cultural resource standards such as impacts on
  historic structures or archaeological resources.
• Other standards relating to environmental quality
  issues

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Guiding principles for determining impact
significance

• use established procedure or guidance
• adapt relevant criteria or comparable cases
• assign significance rationally and defensibly
• be consistent in the comparison of alternatives
• document the reasons for judgements

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Test for significance by asking three questions

• Are there residual environmental impacts?
• If yes, are these likely to be significant or
  not?
• If yes, are these significant effects likely to
  occur?

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Impact significance criteria

• environmental loss and deterioration
• social impacts resulting from environmental
  change
• non-conformity with environmental standards
• probability and acceptability of risk

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Ecological significance criteria

• reduction in species diversity
• habitat depletion or fragmentation
• threatened, rare and endangered species
• impairment of ecological functions e.g.
• disruption of food chains
• decline in species population
• alterations in predator-prey relationships.

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Social significance criteria

• human health and safety
• decline in important resource
• loss of valued area
• displacement of people
• disruption of communities
• demands on services and infrastructure

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Environmental standards

• limits on effluent discharge concentrations
• clean air standards, water quality standards
• policy objectives and targets
• plans or policies that protect or limit use of
  natural resources

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Practical guidance

• Impacts are likely to be significant if they
• are extensive over space or time
• are intensive in concentration or in relation to
  assimilative capacity
• exceed environmental standards or thresholds
• do not comply with environmental policies/ land
  use plans
• affect ecological sensitive areas and heritage
  resources
• affect community lifestyle, traditional land uses
  and values

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Examples

• CERES
• http//ceres.ca.gov/planning/ceqa/thresholds.html
• Ventura County Initial Study Assessment
  Guidelines Thresholds of Significance
• http//www.ventura.org/planning/pdf/ordinances/ini
  tial_study_assess_guide.pdf

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Urban Environmental Problems

• All environmental problems related to land use
• Environmental Management Land Use Planning
• Need to understand land use policy

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Land Use Policy

• Primarily set by local agencies in U.S. (cities
  and counties)
• Policies for the use, intensity, performance
  standards, and location of land uses
• 2 components
• Non-spatial (use, intensity, performance
  standards)
• Spatial (land use map)

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Land Use Policies
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