ENVS402 – Environmental Impact Assessment

7. Environmental Impact pMitigating measures

I. Benefit enhancing measures (selection and implementation)

II. Adverse Impact mitigating measures (selection and implementation)

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7. Environmental Impact Mitigating measuresp g g

The purpose of mitigation measures is to avoid, reduce or minimize unwanted impacts and enhance beneficial impactsimpacts and enhance beneficial impacts

Selection of alternatives is also a form ofSelection of alternatives is also a form of mitigation in terms of impact, cost and technologygy

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Mitigation is. . .Definition of mitigation

g . . .

The implementation of measures designed to reduce thedesigned to reduce the undesirable effects of a proposed action on the

environment

Mitigation is a key part of theMitigation is a key part of the EIA process. It is essential to achieving environmentally

d d i!

Source: ENCAP EA-ESD Course: Mitigation &

Monitoring3

sound design.

Different types of mitigation measures act in different ways to reduce adverse impacts:

Type of measure How it works Examples

Fully or partially prevent an PREVENT contamination of

Prevention & Control measures

y p y pimpact/reduce a risk by:

Changing means or techniqueChanging the site

PREVENT contamination of wells, by SITING wells a minimum distance from latrines.Implement health education

Changing the siteSpecifying operating practices

programInitiate public awareness prog.

Compensatory measures

Offset adverse impacts in one area with improvements elsewhere

Plant trees in a new location to COMPENSATE for clearing a construction site.

Remediation/Correctivemeasures

Repair or restore the environment after damage is done.

Re-grade and replant a borrow pit after construction is finished

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measures

Example of Mitigation:O ti ti t t & t l i tOperating practices to prevent & control impacts

IrrigationPotential impact:salinization of soilssalinization of soilsMitigation: avoid water-logging by using

d f improved on-farm water management, including placement of drainage p gstructures.

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Example of Mitigation:Change of site to prevent & control impactsChange of site to prevent & control impacts

l d Rural road constructionPotential impact: route traverses nesting area for a traverses nesting area for a threatened species of bird Mitigation:

d d Re-route road to avoid nesting site.Also, minimize ,construction noise and other disturbance during nesting season

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nesting season

Reliability of mitigation measures: Reliability of mitigation measures: site & technique changes vs. operating practices

PREVENTION of impacts by changes to site or technique ischanges to site or technique is the most reliable approach to mitigation.

CONTROL of impacts with operating practices is less reliable, because the practices

!, p

must be continued after hand-over of the activity.

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Do I mitigate EVERY impact?

NOT NECESSARILYNOT NECESSARILY.Mitigation is directed at two targets.

serious impacts1 easily mitigated impacts

2

First, the most serious impacts identified by

After addressing the most serious impacts,p y

the EIA process should ALWAYS be mitigated.

there may be small impacts for which mitigation is easy and

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mitigation is easy and low-cost.

7. Environmental Impact Mitigating measuresp g g

A Framework of Impact Mitigation

DesirableAVOIDANCE Alt. Sites/Technology

MITIGATION Actions

COMPENSATION Use as last resort

Undesirable

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7. Environmental Impact Mitigating measuresp g g

Characteristics of Impact Mitigation Measures

Proposed mitigation measures should be able to describe;1 the impact it will avoid mitigate or compensate1. the impact it will avoid, mitigate or compensate 

when implemented,2. an assessment of the effectiveness of 

protection measures,3. the next best alternative,4. the cost of the protection measures,p ,5. and the implementation plan for putting the 

measure into practice.

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7. Environmental Impact Mitigating measuresp g g

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7. Environmental Impact Mitigating measuresp g g

Implementation of Mitigation Measures

Implementation of Mitigation Measures:• should be cost effective and locally applicable and can be 

proposed during different stages of project implementationproposed during different stages of project implementation.

• Pre‐construction (such as compensation for land acquisition),• Construction (such as planning and designing activities)• Construction (such as planning and designing activities),• Operational stages (such as maintenance activities).

• The cost is usually about 10 % of the total cost of the project• The cost is usually about 10 % of the total cost of the project (although it depends on the nature, size, location etc. of the project)

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