Construction and Environment Note Sode

7/29/2019 Construction and Environment Note Sode

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By Prof SACHIN JAIN 1

Construction and environment

By

Prof SACHIN JAIN


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Climate change Ozone layer depletion Acidification

Eutrophication

Depletion ofrenewable resources

Depletion of non-renewable resources

Winter and summer smog

Eco-Toxicity

Generationof waste

Environmental impacts


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A significant part of these impactscome from the construction sector(construction, use and maintenanceof infrastructures).

The impact of use and maintenancecan be significantly more importantthan the impact of construction.

Examples: roads or buildings.


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Quantitative assessment

of all measurable effects

Maintenance of buildings

Production of goods

Transport of goods

Examples of processes or products


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E

xamplesofparametersa

ssessed

Production of goods(for a specific process in a specific factory)

Consumption of raw materials andproducts (quantity/product)

Emission of gases, and of

solid and liquid wastes(quantity/product)

Transport(for a specific truck in a specific trip)

Emission of different gases(quantity/km or trip)

Consumption of fuel,oil, tyres, etc.

(quantity/km or trip)


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Any processExample: production of1 kg of clinker in a kiln

Products

1 kg of clinker

(Energy)(MJ of heat)

Raw materialskg of limestone,

of clay, etc.

Wastes

Solid - Liquid Gaskg of dust, contaminated water, NOx, SOx, ...

EnergyMJ (fuels,electricity)

Productskg of explosives, of

admixtures, etc.


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To be defined:- functional unit

- cradle-grave, cradle-gate- system boundaries


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Examples

A badly isolated building may have a lower environmental

impact up until construction is completed (fewer materials

required) but will have a much higher impact during usebecause of thermal conditioning.

A material can have an important impact in production (for

instance high energy consumption) but very low afterwards

(low maintenance and recyclable) or vice versa.


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What if function changes?

RecyclingLandfill

Abandonment

Repairing,renovating,transforming...

Functional unit to be redefined !(new life cycle)

Demolition


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Construction waste management

for better environment


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Construction and demolition waste overview


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Typical composition of waste

Hardcore recycling rates


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Best practice targets for longer term


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C&D waste possible routes


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Causes of waste on site


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Hacking off concrete becomes concrete waste

Broken bag of crush stone Improper stacking of tiles


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Left over mortar becomes waste Wooden package disposed

Cutting waste of reinforcement

Waste materials are not

segregated from useful material


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Damage of drywall panels

Cutting wasteof dry wall

Lost of plaster while applyingCutting waste of tiles


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Percentage wastage of materials in public housing


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Percentage wastage of materials for various trades for private residential

building


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Wastage management


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Waste Management Hierarchy


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Resource Optimization

(Rethink Design)

Reduce Packaging

Implement efficient,material saving

construction technique

Source Reduction

(Accurate Estimating

& ordering)Prevention

Prevention of waste generation in construction


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Reuse


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Selective Demolition Methodology


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Flow Chart for

Recycling Process


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Various types of crushers


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Uses of recycled material

Secondary aggregates for road (capping layer and sub base)

construction Top soil Drainage media Capillary break layers on contaminated land

Metal (steel reinforcement)

Large timber sections Wood for fuel and kindling and use as a filler material in the

manufacture of medium density fiber board Paving slabs

Bricks


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Concrete the non waste in waste stream


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What is Recycled Concrete?


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Concrete to be Recycled


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Where Does Recycled Concrete

Come From?

Local Sources

CRD Construction, Renovation & Demolition

Buildings

Road/Parking Lot Reconstruction


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Concrete Crushing


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Benefits of Recycling Concrete

Local Product Local Sources

Reduces Truck Traffic

Alternative to a Non-Renewable Resource

Cost Savings

No Disposal Fees

Better Trucking Utilization (Reduced Costs)

Allow up to 10% Deleterious Materials


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Processed Concrete

Plasma Gasification Cupola for energy production from wastage


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Plasma Gasification Cupola for energy production from wastage


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This method is used in St Lucie Country which contains more than 4million tons of MSW.

The MSW will be conveyed to one of of six cupolas that will have aceramic interior and a steel exterior, the latter immersed in water

Six plasma torches will create arcs of artificial lightening in eachcopula that will heat the space to temperatures greater than thoseon the surface of sun, changing the municipal waste to a gaseous orliquid state.

The gas formed will exit the chamber at a temperature ofapproximately 2300oF (1260oC) and will be transported to a gascleaning facility, where wet scrubbers and a wet electrostaticprecipitator will extract sulfur, chlorines, dust and such volatilemetals as mercury and cadmium.

After the gashes been cleaned it will enter a gas turbine electricgenerator with a capacity of 160 MW per day.


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40 MW of which will be used to power the gasification plant andremaining 120 MW is supplied to grid.

Supper heated liquid by product will be cooled to from a solidvitreous slag that will be broken to small granules.

These granules can be used as aggregate in asphalt or concrete.

The new plant will be capable of processing 3000 tones (2700metric tones)of MSW per day.

Some of 2000 tones of new MSW will be taken from existing

Landfills. Plant is capable of processing dewatered sludge and can take up to

15% of 3000 tones daily load as sludge.


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Construction of Dry Tomb Land fill


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Leave it Alone


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Environment Impact Assessment


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Environmental Impact Assessment (EIA) is an instrument ofreconciliation.

The Council on European Economic Committee, in their directive tothe member states, highlights the objectives of EIA.

The effects of a project on the environment must be assessed inorder to take account of

The concerns to protect human health,

To contribute by means of a better environment to the quality of life,

To ensure maintenance of the diversity of species and to maintainthe reproductive capacity of the ecosystem as a basic resource of

life.


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Prevention Rather Than Cure

It is essential that consequences of projects, plans or policies

at different levels be assessed before they are executed.

EIA examines these consequences and predicts future

changes in the environment.

It guides administrative agencies in balancing conflicting social

values and environmental quality.

It helps them to make the best choice among various available

options.

EIA foresees and avoids potential dangers.


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The Mandatory Model

Power coupled with duty is the most salient feature of the mandatorymodel of impact assessment.

The decision-making agency is obliged to study the impact of adevelopment proposal before it is approved.

The EIS serves as a guarantee of the right to information and abasis for proper impact assessment.


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Pleas Against And In Favor

The EIS on which assessment is made is often too lengthy,

Environmentalists may try to delay development by raisingfalse pleas of defects in impact statements.

EIS may impose procedural burden rather than afford anopportunity to improve decision-making.

Public participation and judicial review play key roles asintegral parts of mandatory model.

They make EIA into a reasoned and objective process andmake it an important tool in protecting and managing theenvironment.


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The Discretionary Model

Merits

It depends on the discretionary powers of the administration.

This model exhibits flexibility and maintains a harmony betweendevelopmental needs and environmental values;

experts can make a choice from available alternatives.

Quick, expert and timely decision-making is the advantage of thismodel.

Public participation is not allowed as a matter of routine,

Demerits

Experts within the government may go wrong,

Reasons for decisions may not be disclosed;

Interests of weaker or vulnerable groups and regions could beneglected;

Alternative opinions, expressed outside the realms ofadministration, may be overlooked or disregarded;


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METHODOLOGY OF EIA


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The EIA can be broadly divided into the following steps,

basics,

environmental setting,

impact prediction and assessment.


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Basics

One must have a fair understanding and knowledge of thestudy.

Starting with the need for the project one must identifyalternative solutions to meet this need.

Also with these solutions a no-project alternative should be

included.

Since impacts due to alternative solutions may widely differdepending upon the alternative itself it is necessary to broadlyexamine each alternative and the factors that are most

affected.

Environmental Setting


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Environmental Setting

It provides baseline information against which predictions andassessments of the impacts for each alternative can be compared.

The factors can be classified under physical-chemical (e.g. air andwater quality, soil fertility, etc.) biological (flora and fauna), cultural(archaeological sites, recreation, etc.) and socio-economic (populationcharacteristics, economic state, etc.).

Impact Prediction and Assessment

This is a complex task involving widely different techniques in differing

disciplines.

As measurement techniques vary, interpretation varies, and therefore a

number of methodologies have been developed for presentation of theseimpacts to decision makers and the general public public.


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Methodologies for Environmental Impact

Assessment

Adhoc

Checklists

Matrices

Networks

Overlay techniques

Adh


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Adhoc

These were the first methods to be used in the preparation of EIA.

The procedure involves the bringing together of various experts in

particular fields to identify impacts in their area of expertise.

The environment is generally divided into broad categories, the

assessment of which could be intuitive or subjected to qualitativeinterpretation of quantitative results.

The adhoc approach has little or no formal analytical structure and

at most provides only a preliminary review.

Ch kli t


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Checklists

Checklists can be of various types ranging from simple to fairlysophisticated.

Simple checklists have no guidelines on how to measure andinterpret environmental impacts.

Descriptive checklists are more structured with identification ofenvironmental parameter and guidelines on how parameterdata is to be measured.

Scaling checklists go a step further by providing information onhow the parameter values are scaled.

Lastly, there are scaling-weighting checklists that provideadditional information on relative weights of importance ofeach parameter.


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Interaction Matrices

This method develops on the checklist method byincorporating a list of project activities to a checklist of potentialimpact environmental characteristics.

Developed by Leopold et al. (described in Canter, 1977) themethod involves the use of a matrix with 100 specified actionsand 88 environmental items.

Each cell represents an impact that is a result of interactionbetween an action and an environmental item.

As with the EES two aspects of each impact needs to bedetermined, namely, magnitude and importance.

Both of these are assigned a numerical scale from one to ten.


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It is possible to expand or contact the matrix, i.e. action or

environmental items not included can always be added and vice-

versa i.e. items or action having no relevance he project underquestion can be deleted.

It is also possible to represent cell entries as qualities estimates of

the cause effect relationships.

Networks


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Networks

Network approaches can expand on the matrix theme byintroducing a cause condition effect network, which allowsidentification of cumulative or indirect effects.

The network is depicted in the form of a tree, called arelevance or impact tree, and is used to relate and recordsecondary, tertiary and higher order effects.

To understand this technique considers the impact tree.

Activity A has two primary impacts, three secondary impactsand four tertiary impacts.

There are ten branches of the tree.

O l T h i


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Overlay Techniques

This methodology essentially consists of developing a set of

maps of environmental characteristics such as physical, social,etc. for a project area and overlaying these maps

(transparencies) to create a composite map, which shows the

spatial distribution of the selected impacts.

The overlay approach is generally effective in its ability to set aproposed project within a geographical context and to indicate

spatial relationships between the environmental factors that

are regarded as relevant to the assessment of the project.

However it cannot be used to identify impacts or identifysecondary and tertiary relationships.


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The method has been used to identify the optimal routing fortransmission lines and site selection processes for coal and oilrelated developments (Codoni et al., 1985).

The method was also applied on the Huasai- Thale- Noi RoadProject in Thailand where the project was halted due toenvironmental concern.

An alternative route was determined by using rough overlays of theenvironmental site selection parameters (lohani and Halim, 1986).


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Conceptual EIA of large

scale electric power plants

India produces electricity mainly from coal hydro and from nuclear


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India produces electricity mainly from coal, hydro, and from nuclearalbeit in a limited way.

The environmental impacts from each of these modes are widely

different. Also within each type, differences in magnitude arise due to location

features, type of inputs, equipments, etc.

The setting up of a power plant leads to growth and development inthat area.

These benefits would arise irrespective of the type of power plant.

The negative impacts occur through the air water and land mediaand are type and location-specific.

The issues/methodology for quantification of the impacts and theirrelative weighting for different type of power plants are brieflydiscussed below.


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Coal based thermal power

generation


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Air Pollution

Air pollution occurs as a result of the emission of

Particulates (SPM),

Oxides of Sulphur (SOx),

Oxides of Nitrogen (NOx),

Fly ash


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Air pollution control

SPM Control

SOx Control

NOx Control

SPM C t l


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SPM Control

Pre and post combustion control measures exist for all the majorpollutants.

At present, the installation of electrostatic precipitators (ESP) for thecontrol of SPM emissions are mandatory in India

The average cost of SPM control by ESPs is approximately 1 % of thecost of generation.

ESP usually operate at efficiencies of 99 percent and above, theefficiencies generally being relatively insensitive to particle size butgrade efficiency curves indicate a minimum in the 0.2-2 micrometerrange (Wall 1986).

Fabric filters are preferred for their high overall collection efficiency,which is maintained over a wide range of particle sizes.

For submicron particles, bag filter systems in terms of collectionefficiencies are superior to all other control technologies.

SO C l


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SOx Control

Given the low levels of sulphur in most Indian coals, the emissionsof SOx in most cases are likely to fall within ambient standards

Only those areas that are already having high sulphur emissionssuch as the Singrauli area or in certain metropolitan cities wouldrequire Flue Gas Desulphurisation (FGD) equipment.

Damage from SOx emissions are maximum in areas which alreadyhave heavy particulate loading.

FGDs typically operate at efficiencies around 90 percent andcontribute to a 25-30 percent increase in the cost of generation.

NOx Control


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NOx Control

NOx emissions were never considered significant contributorsto environmental degradation.

However, in recent years increasing attention is being paid tothe environmental damage from NOx emissions and methodsto reduce it.

Low NOx burners provides an inexpensive way with operatingefficiencies below fifty percent.

Selective Catalytic Reduction (SCR) equipment operate atefficiencies of approximately 85 percent but increase the costsof generation by approximately 7- 10 percent

Quantification of environmental damage


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Quantification of environmental damage

The damage caused due to air pollution from a power plantwould depend upon the dosage received by the surroundingpopulation, as well as their physiological, socio- economic andhealth characteristics.

The dosage received by the population is a function of both theground level concentrations as well as the period over whichthe population is exposed.

Concentrations are generally computed on a short term (lessthan 24 hours), seasonal and on an annual basis.

Their levels depend upon both the technical features of theplant (quantity and characteristics of the fuel used, type ofplant and state of operation, height of stacks, etc. andatmospheric conditions (wind directions, atmospheric stability,etc.).

These can be computed using several approaches, the mostcommonly used one being the Gaussian Dispersion Model.


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In order to determine the exposure, the seasonal/annual concentrationsfrom the plant will need to be determined added to the backgroundconcentrations, the sum of which when mapped the surrounding populationwould give the total exposure.

The mapping of pollutants onto the recipient population, requires dose-response curves of the population

Therefore the estimate of damage is based on air quality standards.

A value function curve for air would be used to ascertain the deterioration inair quality.

Figure below shows the short term and long term concentration for differentwind speeds.


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No Typical emissions from a power plant : Scenario 1 (down wind ad unstable

conditions).

Ash Disposal


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Ash Disposal

Given the high percentage of ash in Indian coals (averaging 40

percent), significant quantities of both fly and bottom ash aregenerated (80:20 respectively).

The ash can be disposed or utilized in a number of ways

Disposal

Ash Utilization

Disposal


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Disposal

There are two types of disposal

Wet disposal system

Dry disposal system


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Wet disposal system

The most common disposal method is the wet disposal system.

In this System, the ash is transported by slurry pipelines and

deposited at the disposal site in a fluid state.

Every tone of fly ash requires approximately 8-10 liters of water to

convert it to slurry System differences arise in terms of how the

transport water and supematent are handled in terms of treatment

and discharge, recycle, evaporation or impoundment.

Land requirements are roughly 0.4 ha per MW installed capacity.


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Control of leachates (discussed below) and prevention of groundwater contamination IS more The primary advantage of wet systemsare that they are simple, relatively inexpensive to operate andnormally unobtrusive (quiet, no fugitive dust, no transport traffic).

They are also flexible with respect to short-term variability

The main disadvantages are associated with the disposal site.

A large disposal area is required due to the large volume of effluents.

Preparation of the disposal site requires dams and dykes whichincrease the cost.

difficult to ensure, and liners are required. Flexibility to long termchanges are less.

D di l t


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Dry disposal system

The dry disposal system transports and deposits the waste in the

landfill as a solid.

Bottom ash is transported hydraulically to a dewatering bin or pond;

Fly ash is collected in silos for transport to the disposal site.

They are generally transported and disposed separately.

Ash is typically trucked to the landfill, dumped, spread and

compacted with the use of water.


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Advantages of dry disposal techniques lie in a lower requirement forland and water and often lower capital costs.

Control of leachates and ground water protection is easier. Site closure and revegetation is simpler and cheaper.

The most important positive aspect is the ease of reclamation infuture use of ash

The primary disadvantages centre on greater quantities of dust,noise and traffic, and higher operating costs.

Water Pollution due to thermal plant


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Water Pollution due to thermal plant

Both thermal and chemical discharges are responsible for waterpollution.

Thermal pollution of the water bodies occur with boiler blowdownand/or when condenser cooling occurs.

This could affect the aquatic system in a number of lays.

For some fish species, warmer water spells disaster in the form ofincreased mortality rates and increased susceptibility to disease.

For some other species, warmer water could imply a higher metabolicrate, which leads to shorter maturing periods and shorter reproductioncycles.


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The cooling systems fall mainly into two categories,

Once through systems: These systems circulate water through

the plant condensers and return it to the environment

Closed cycle systems: These systems circulate water from the

condenser to another device in which the flow is cooled,generally by evaporation to he atmosphere.

Common used cooling devices are cooling towers, cooling

ponds and spray systems.


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For regulatory purposes, the discharge streams from power plants aredivided into several point source categories of

Cooling water, i.e. once through and cooling tower blowdown,

Ash transport water, i.e. fly ash and bottom ash transport water,

Metal cleaning wastes,

Low volume wastes,

Material storage run off i.e. coal pile and ash pile run off


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Hydro


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Building of a dam or formation of a reservoir leads to the

submergence of large areas If land.

The two major issues therefore are

large-scale displacement and rehabilitation of the people and

loss of large areas of land under forest cover.

Large Scale Displacement


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Large Scale Displacement

Displacement and consequently the rehabilitation of people from the landthey have occupied for centuries is a tough task.

People are emotionally attached not only to the land but also to theirlifestyles.

Although in recent years rehabilitation packages offered have been veryliberal but their implementation is not perfect.

This leads to a large degree of discontent amongst the oustees.

Often tribal who are displaced from their forest homeland and have tochange their way of life.

Therefore there are two features that need to be looked at in the designstage.

the rehabilitation package

the scale of displacement

Quantification of displacement


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Quantification of displacement

Value function graphs would need to be drawn.

Rehabilitation packages would range from 0 to 10 starting from the

worst to the best.

The scale of displacement would range from 0 (for large number of

people displaced, say > 100,000) to 10 (none, or a very small

number of people displaced).

Forest Loss


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Forest Loss

Often, with the construction of a darn, large areas of forest are lost.

Here timber and other minor forest products lost also environmentalservices like prevention of soil erosion, climate regulation,production of oxygen, absorption of carbon-dioxide and mostimportantly a provision of a habitat for birds and animals is

damaged.

In addition, tribal and other communities have their lives deeplywoven around forests.

Therefore this is a major issue and should be included in theevaluation

Q tifi ti f F t l


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Quantification of Forest loss

This is difficult to quantify.

The scale would be similar to the scale of displacement

graph, i. e. 0 for large forest loss and 10 for no forest

loss.

Others


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Others

These losses are

Siltation,

Diseases (malaria, encephalitis, schistosomiasis, Fluorosis, etc.)

Risk of enhanced earthquakes in the area.

Although these are of relatively less importance than the two majorissues, value function graphs can be made for each impact.


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Nuclear

The setting up of a nuclear plant may pose radiological dangers toth l l l ti i th f f l l l di ti f d


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the local population in the form of low-level radiation, surface andground water radio-active contamination, and from waste disposal atplant site.

As part of the plant design radioactive discharges are kept muchbelow threshold (safe) levels, and therefore based on designoperating features, the normal operation of a nuclear plant will causeno radiological threat to the neighboring population and countryside.

In the event of an accident (due to internal or external causes) alarge release of radioactivity may result in catastrophicconsequences.

Non radiological threat includes 'thermal cooling' of the typedescribed in the case of coal plants but with a higher degree of

magnitude.


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Finalizing the EIA


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Value function graphs provide a way of quantifying the majorimpacts.

These impacts need to be weighted in terms of their relativeimportance.

Since this is a value judgment, the value assigned is arrived at byconducting a survey.

The sample group needs to be carefully chosen over the cross-section of society.

It is important that the representative sample be truly representativeof the population, and not just the policy makers.


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This will ensure the value of the weights are unbiased towards anygroup and therefore would reflect an objective result.

Issues such as displacement would probably attract a wide range ofvalues which is major cause for protest in Hydro projects.

Once the weight and scores are all' obtained, the EIU with andwithout the power plant can be calculated.

If the result is positive then the setting up of the power plant isenvironmentally acceptable

Reference


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Reference

Construction and Environment by NICMAR

Developing a strategic approach to construction waste

by Gilli Hobbs

Construction and demolition waste management A hand

book for contractors and site managers by A FAS &

construction industry federation initiative


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THANKYOU

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