Potential negative impacts

Mitigating measures

Direct

Resuspension of toxic sediments from construction of offshore pipelines

• Select alternative location for laying pipeline
• Use alternative pipeline construction techniques to minimize resuspension of sediments (e.g., laying pipeline versus burying pipeline)
• Lay pipeline at a period of minimal circulation

Interference with fishing activities from offshore and nearshore pipelines

• Select pipeline route away from known fishing areas
• Mark on a map the location of offshore pipelines
• Bury pipeline that must be located in critical fishing areas

Habitat and organism loss along offshore and upland pipeline ROWs and pumping and compressor station sites, and increased access to wildlands

• Select ROW to avoid important natural resource areas
• Utilize appropriate clearing techniques (e.g., hand clearing versus mechanized clearing) along upland ROWs to maintain native vegetation near pipeline.
• Replant disturbed sites
• Use alternative construction techniques

Erosion, run-off, and sedimentation from construction of pipeline, grading for access roads and substation facilities

• Select ROW to avoid impacts to water bodies and hilly areas
• Install sediment traps or screens to control run-off and sedimentation.
• Use alternative pipeline laying techniques that minimize impacts
• Stabilize soils mechanically or chemically to reduce erosion potential

Alteration of hydrological patterns

• Select ROW to avoid wetlands and flood plains
• Minimize use of fill
• Design drainage to avoid affecting nearby lands

Evasion of exotic species and habitat fragmentation

• Select corridors and ROW to avoid important wildlands and sensitive habitats
• Maintain native ground cover (vegetation) above pipeline
• Make provisions to avoid interfering with natural fire regimes

Loss of land use due to placement of upland pipeline and substations

• Select ROW to avoid important social (including agricultural) and cultural land uses
• Design construction to reduce ROW requirements
• Minimize off-site land use impacts during construction
• For buried pipelines, restore disturbed land along ROW

Creation of barriers for human and wildlife movement

• Select ROW to avoid travel routes and wildlife corridors
• Elevate or bury pipeline to allow for movement

Increased traffic due to construction

• Phase construction activities to control traffic
• Construct alternative traffic routes

Chemical contamination from wastes and accidental oil spills

• Develop waste and spill prevention and clean-up plans

Hazards from gas pipeline leakage or rupture

• Clearly mark locations of buried pipelines in high-use areas
• Develop emergency evacuation plans and procedures
• Monitor for leaks
• Install alarms to notify the public of accidents
• Utilize spill containment techniques
• Clean up and restore affected areas

Indirect

Induced secondary development during construction in the surrounding area

• Develop comprehensive plan for location of secondary development
• Construct facilities and provide financial support to existing infrastructure

Increased access to wildlands

• Develop protection and management plans for these areas
• Construction barriers (e.g., fences) to prohibit access to sensitive wildlands

Environmental parameters

Impacts

Mitigation measures

Physical resources

Air quality

• Air quality is affected due to exhaust gas, dust, noise, and vibration in the construction phase
• Overall a minor consideration for water resources projects

• Frequently sprinkling water on fresh construction spoils
• Maintaining green belt
• Providing masks to people working in dusty environment

Water quality

Surface water quality

• Development of new industries and population concentration due to urbanization leads to increased wastes and hence deterioration of river water quality
• Deforestation leads to erosion which in turn causes increased sediment load and hence high turbidity in the river
• Intensification of agriculture due to increased demands for food leads to leaching of fertilizers which affect surface water quality

• Catchment area treatment to reduce sediment load
• Adequate treatment of effluents to attain the standards prescribed in appropriate International Standard (IS) and consideration of assimilative capacities of receiving water bodies
• Proper control of discharges from non-point sources
• Efficient application of pesticides, fertilizers, and other agrochemicals to reduce their losses due to leaching
• Proper treatment of domestic and industrial wastes to reduce the concentration of nutrients reaching water bodies especially quiescent ones
• Efficient application of fertilizers to the crops so that the amount leached is kept to a minimum
• Soil conservation measures to be adopted

Groundwater quality

• Percolation of pollutants such as pesticides and wastes from soil and surface water bodies may contaminate groundwater

• Prevention with use of liners
• Use of leachate collection system
• On-site chemical treatment before discharge

Land quality

Soil

• Deforestation due to new development such as industries and population growth and increased flood and drought leads to erosion of soil
• Fertilizer and pesticide residue may lead to a change in the physico-chemical properties of the soil and increased salinity of soil

• Education of relevant people to develop widespread understanding of the problems that are likely to arise and the methods of sound land use
• Actions by individuals through local mechanisms with the help of the governments
• Efforts to relieve economic and social maladjustments in the use of land and which impede conservation

Land use

• Change in land use patterns
• Loss of agricultural land

• Proper siting of the project is very important

Other specific physical resources

Water hydrology

• Change in surface and ground water hydrology (existing flow patterns) due to construction of the water resources project
• Increased sedimentation in the river or other water body

• Adequate site investigation and appropriate site design and siting is necessary
• Use of sedimentation models will help estimate the change in hydrologic regime

Drainage

• Change in the natural drainage pattern occurs due to erosion of soil and changes in level of the groundwater table
• Components such as deep percolation from reservoir and canal irrigated areas and seepage loss from main canals, branch canals, and tributaries lead to a change in groundwater recharge

• Reservoir operations should be such that two or three spills of reasonable discharge are allowed in the river on a regular basis
• Minimum flow in the river should not be less than the average 10 days minimum flow of the river in its natural state
• Priorities and requirements downstream should be taken care of

Meteorology

• The reservoir causes higher relative humidity due to increased evaporation from the reservoir and the newly irrigated area
• There can also be moderating effect on extreme temperatures if reservoir is very big

• Proper siting
• Regular monitoring

Seismicity

• Construction of the water resources project involving drilling, blasting, and quarrying may affect the seismicity of the area, especially if there are already existing major faults nearby

• The prediction of seismicity can be done with the help of equations
• The design should ensure that the hydraulic structures area is safe against the largest expected earthquake
• For large reservoirs of depth > 100 m or/land volume 10⁹ m³ detailed investigations of nearby faults must carried out
• A more detailed description of seismic consideration is given in the EA Sourcebook (see Further Reading)

Water resources

• Impact on rainfall, run-off, and groundwater levels
• Increase in live storage capacity and hence utilizable water

• The live storage capacity can be determined by matching demand and water availability patterns
• This matching is possible by using mass curve technique, sequential peak algorithm or through stochastic simulation
• Utilizable water should be worked out in relation to the ratio of live storage capacity to average annual yield
• For maintaining live storage capacity on a long-term basis, appropriate sediment control measures in the catchment area should receive priority attention
• Sediment deposition in a reservoir can be controlled to a certain extent by designing and operating outlets in the dam in such manner as to point selective withdrawals of water having a higher sediment content
• The effective method of silt control is by releasing water through a series of outlets at various elevations

Ecological resources

Vegetation (flora)

• Air pollution during construction leads to damage to plant life
• Development of new industries and urbanization leads to deforestation and loss of valuable species

• The total forest area lost by siting of the dam, reservoir, canals, and other structures can be estimated by superimposing the project layout maps on the land use maps
• The loss of forest in terms of its biomass can be estimated on the basis of forest productivity
• The total area of forest loss due to reservoir, dam, canals, and other items have to be afforested as a compensatory measure

Aquatic life

• Population concentration leads to increased wastes in the river, nutrient uptake, and light interruption and hence reduced primary productivity of useful planktons
• Increased nutrient load leads to reduced fish yield
• Deforestation leads to high turbidity of river water and hence low primary productivity and low fish yield

• From baseline data it is possible to identify the migrating fish species as well as their migration routes upstream and downstream
• The change in fish species due to change in hydraulic regime of the river can be predicted by observing other similar project areas

Terrestrial wildlife

• Displacement and reduction in species of wildlife due to habitat encroachment
• Danger of extinction of endangered and endemic species

• Proper site selection and rehabilitation measures by the creation of alternative habitats

Ecological cycles

• Danger of extinction of unique or rare species

• If the area to be affected contains any unique or rare species, an alternative site has to be considered for the project site or suitable measures should be taken to rehabilitate the species

Quality of life values

Socio-economic

• Human population displacement
• Change in socio-economic structure, standard of living, income distribution, etc.
• Induced secondary development including demands on infrastructure

• The rehabilitation plan should consider socio-economic aspects as well as quality of life and the requirements of society
• In this regard various state governments have formulated policies which could be followed

Cultural

• Changes in demographic patterns and social and cultural values

• Develop plans to educate workers on sensitive values and patterns

Aesthetics/historical/archaeological/tourism

• Visual impact on historical, archaeological, and cultural resources and on landscapes
• Modification of historically or archaeologically important structures
• Decline of tourism due to deterioration of aesthetic value due to pollution

• Rehabilitation of monuments likely to be affected by the project should be undertaken if possible
• Sites chosen for total rehabilitation should be similar to the earlier one in terms of access and environmental setting

Public health

• Alteration in vectors and risk of transmission of vector-borne diseases as a result of the project, arising mainly from urbanization and new bodies of water

• Three types of measures should be taken for public health: vector control, increase in awareness of public health, and engineering design and control
• Vector control can be achieved through engineering, biological, chemical, and agrochemical measures
• Engineering design and control measures include proper design and straight alignment of canals, lining of canals, provision of steep and regular banks for the reservoir, provision for clean drinking water, sanitary facilities, bridged crossings, adequate drainage measures, and maintenance of canals and drainage systems in order to prevent creation of better habitats for vectors

Other specific values

• Population rehabilitation

• Displacement of local population occurs due to the project
• Migration to project area leads to rise in population

• Population projection should take into account migration to project area because of enhanced agricultural and other economic activities
• Proper steps for rehabilitation of displaced farmers, etc., should be undertaken

Human use values

Public utility services Water supply and sanitation

• Existing sanitary and waste disposal practices could have linkages to qualities of surface water and groundwater

• The water requirement can be predicted on basis of crop, water, livestock, and human requirements after taking into account rainfall and evapotranspiration

Accommodation

• Increased water requirement due to population growth and growth of industries
• Increased demand for housing due to growth of population

• The domestic water demand for present and future can be worked out by data on population
• The industrial water demand can be estimated on basis of survey
• Provision of proper housing facilities for the newly arrived people as well as the local displaced people

Employment

• Increase in employment opportunities
• Means of livelihood of farmers/regional tribes likely to be affected

• Proper planning of employment opportunities
• Provision of employment to displaced farmers/regional tribes
• Careful planning of industrial and urban boom

Other specific values

Flood and droughts

• Increased flood and droughts due to deforestation and urbanization and hence problems in reservoir management

• Prediction by use of probabilistic models using data collected for previous years
• Proper design of houses (stilts) for floods and efficient water supply via tankers, etc., in time of drought

Environmental parameters

Impacts

Mitigation measures

Physical resources (a) water quality

SPM - Dust and coal dust

• Respiratory diseases, emphysema, asthma
• Cardiovascular diseases
• Decrease in plant respiration, change in foliage pattern
• Damage to materials

• Good housekeeping, such as water spraying, shielding of dusty areas, cleaning of equipment, and maintaining proper operating methods
• Use of coal dust suppression systems
• Transport of coal in a slurry form
• Agglomeration system whereby fines of coal are bound to the larger particles

SO_x, NO_x - Emissions from vehicles and burning of wastes

• Increased mortality, morbidity, irritation, bronchitis

• Avoid burning of waste material
• Proper gaseous control equipment

Physical resources (b) water quality

Surface water quality

Affected by:
• dredging and reclamation
• discharge of sanitary effluent

• Construction of breakwater and silt basin to minimize sediment release

Groundwater quality

Affected by
• oil spills/leakages
• soil run-off

• Avoid overspills from loading barges
• Provide floating booms or skimmers to contain oil spills
• Use of chemical dispersants to dissolve floating oil
• Provide drainage control systems, ponding basins, storm drains

Physical resources (c) land quality

Soil

• Soil erosion due to earth moving during construction activity

• Proper design and siting; avoid sensitive areas
• Excavation of accumulated sand to mitigate adverse effects of erosion

Land use

• Change in land use, loss of agricultural land

• Resource management
• Compensation to displace land owners
• Displaced fishermen to be given financial assistance or alternative employment
• Strict boundary regulations should be enforced to avoid illegal settlements and overspill of activities
• The boundary should be securely fenced and regularly inspected

Other specific physical resources

Water hydrology

• Change in the hydrological regime due to construction and operation of ports and harbours
• High demand for raw and potable water

• Adequate site investigation and appropriate site design is necessary
• Emphasis is to be placed on the need to establish objectives and formulate a methodology
• Provision of an adequate water supply system including pier installation to supply freshwater to ships

Ecological resources

Vegetation (flora)

• Degradation/depletion of forest, especially mangrove forests which may affect local fisheries

• Alternative site selection
• Afforestation, social forestry
• Green belt around the project as a buffer

Aquatic life

• Substantial loss of marine life
• Habitat destruction and species loss

• Timing of activity so as to avoid spawning/migratory activity

Terrestrial wildlife

• Displacement of roosting/breeding/feeding sites for the coastal birds
• Depletion of food sources for the birds or oil coats on birds and fish due to oil discharges
• Habitat encroachment and increased hunting

• Alternative site selection for preventive reasons
• Re-establishment of habitat in some other area

Other specific ecological resources, e.g., coral reef

• Destruction of corals due to silting from the construction activities, disposal of dredging spoils, and structural damage from boats during collisions

• Avoid undue disturbance
• Minimize sediment release from dredging and barge loading
• Draft harbour regulations for piloting, anchorage, and ship movements

Quality of life values

Socio-economic

• Human population displacement
• Urbanization
• Induced secondary development including demands on infrastructure

• Select alternative site or site layout to avoid displacement/relocation of displaced people
• Land use planning
• Provide infrastructure plan and financial support for increased demands
• Construct facilities to reduce demands

Cultural

• Changes in demographic patterns and social and cultural values and patterns

• Develop plan to educate workers on sensitive values and patterns
• Provide behavioural/psychological readjustment programmes

Aesthetics/historical/archaeological/tourism

• Destruction of important archaeological/historical sites thereby affecting the cultural resources
• Visual impacts due to accumulation of waste such as floatables, liquid/solid, and dredging wastes

• Prior archaeological survey/excavation
• Proper design and siting to avoid any such problems
• Disposal regulations
• Normal standards of good design and maintenance should be adopted to avoid visual clutter

Human use values

Public utility services

• Increase in demand for public utility services such as water supply, sanitation, power, surface transport, and post and telegraph

• Provision of adequate water distribution system
• Provision of adequate collection, treatment, and disposal facilities for sanitary waste
• Local police, fire, and medical facilities and other basic amenities of a township to be provided

Employment

• Increase in employment opportunities with onset of project and impending growth of industries, towns, and related support services

• Proper planning of employment opportunities
• Generation of employment for local people