Construction and Operation of a Bridge

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The second example is an EIA for the construction and operation of a bridge. Again there are impacts which are similar all around the world while constructing a bridge,

Table 1 Factors to be considered when determining environmental sustainability of a hydro project

Factor Explanation of factor

Involuntary resettlements Hydro projects sometime necessitate the relocation of people. The less that people are affected, the better the project.

Biodiversity Biodiversity should not decline as a result of the project and obviously no extinction of species should occur.

Fish The issue of fish is related to the loss of protein (how do people depend on fish in their diet for subsistence?) and loss of revenue from sales (commercial fisheries). (Ecological point of view is included in the biodiversity factor.)

Sedimentation Generation capabilities of the project must be long term. Reservoir useful life must be long so that power generation would not be curtailed by sedimentation.

Land Land requirements are associated with land use in terms of economic activities (agricultural production, forestry).

Water quality Project implementation should make sure that acceptable water quality is maintained for downstream users. All pollutants should be at acceptable level.

Downstream flow Water regulation by hydroprojects should not be detrimental to irrigation or to important ecosystems

(mangrove, wetlands, and floodplains). Benefits such as flood control, urban and industrial water supply, multiple uses are considered a plus.

Integration of project in The project should be well integrated to future activities in the region. the region

Greenhouse gases Total greenhouse-gas emission should not exceed equivalent emission from gas-fired power generation emission schemes.

Table 2 Potential impact to the physical and biological environment during construction phase of a hydro project

Environment component

Construction phase

Project interaction

Potential impact

Soil

Water resources and hydrology

Atmospheric environment

Terrestrial resources

Aquatic resources

Soil quality

Erosion/site runoff Excavation

Groundwater

Surface water (Hydrology and floodplain) Climate/Air quality

Human health and safety Plant species at risk Animal species at risk Designated areas and other critical habitat features

Benthic invertebrate Fish

Fish habitats

Macrophyta

Algae

Planktonic organisms

Excavation Blasting

Release of contaminants Reservoir creation Air emissions

Greenhouse gases emissions Ozone depletion substances Air emissions

Construction activities including clearing, grubbing, blasting, and cut and fill Noise

Accidental release of contaminants Surface runoff grading, and grubbing creating sediment, runoff and erosion River crossing Blasting

Accidental release of contaminants

Alternation/displacements of aquatic and terrestrial habitat Mortality (individuals of different species) Interface with fish passage and animal migration Degradation of aquatic and terrestrial habitat Effects on water quantity Effects on water quality

Effects on surface water quantity Reduction in air quality to unacceptable level

Alternation/displacements of habitat Mortality (individuals of different species) Noise and physical disturbance Alternation/displacements of habitat Mortality (individuals of different species) Degradation of habitat Interference with fish passage while other impacts may vary according to the climate, location, size, or function of the bridge.

As was mentioned above the first steps in EIA process are similar and are not dependent on a project type. The screening stage has to obtain information about proposed project (the project type, the size, the capacity, the location, the character of the activity, and possibility of cumulative effects with other types of anthropogenic activities) and the investor. An important part of the screening stage is an identification of the necessity of the project. In the case of a bridge construction, the most common reasons are to connect two places which are not naturally connected and to improve transportation and decrease time and energy to get from one place to other. The secondary reason for building a bridge can also be protection of natural area with high environmental and ecological value, which would be otherwise exposed to traffic and to all negative consequences connected with it. An important part of the primary step is an identification of the proposed location as well as the identification of alternative options. A description of technical and operational solutions has to be part of the screening stage as well as information about starting and ending date of the activity.

The second stage of EIA process, the scoping stage, takes into account all key activities connected to a bridge construction and operation. The impact can be separated into impact during the preparation, construction, and operational period.

The development would involve the excavation of construction materials, the excavation of abutments, construction of the bridge, access roads, and stabilization of banks. There are some key operations during precon-struction, construction, and operational and maintenance periods, which can be used as a guide for assessing impact. The preconstruction program will include

• the construction of new roads to the bridge if it is necessary,

• the improvement of existing roads to facilitate delivery of construction plant and materials,

• the identification of stone quarries and borrow pits,

Table 3 Potential impact to the physical and biological environment during operational phase of a hydro project

Environment component

Operational phase

Project interaction

Potential impact

Soil

Soil quantity

Erosion/ site runoff Water level fluctuation

Alternation/ displacements of habitat y h P

Water resources and hydrology v n e al ic gi lo iol

Climate and air quality

Terrestrial resources

Aquatic resources

Surface water

Groundwater Sediment

Hydrology and floodplain

Microclimate

Greenhouse gases emission

Plant species at risk Animal species at risk Designated areas and other critical habitat features Benthic invertebrate Fish

Fish habitats Macrophyta Algae

Planktonic organisms

Erosion/site runoff Thermal stratification Release of contaminants

Increase groundwater elevation

Release of contaminants

Reservoir creation Erosion/ site runoff Reservoir creation Water level fluctuation

Reservoir creation Air emissions

Filling of the reservoir Accidental release of contaminants

Barrier to fish passage Seasonal changes of water quality caused by thermal stratification Disturbance to river continuum

Effects on water quality Effects on water quantity

Effects on water quality Effects on water quantity Effects on quality Effects on quantity Effects on surface water quantity Changes of natural flows and their periodicity Local changes in climate Reduction in air quality to unacceptable level

Alternation/ displacement of habitat

Decrease fish production Mortality

Behavior changes

• the building of housing and other facilities for construction workers,

• the building of a site office,

• the harvesting of timber, or other type of clearance of the present vegetation.

All of these activities have the potential to create environmental impacts. Areas of particular concern will relate to the selection of sites for extracting construction material. The construction program will include

• temporary diversion of the river course (to allow for construction in riverbed),

• excavation for buried pile cap,

• mobilization of a pile driver to the river bed,

• pile driving for pier support,

• excavation of abutments,

• bending and tying of steel (for the abutments),

• construction of piers and superstructure,

• laying of the asphalt, and

• stabilization of the banks.

The operational and maintenance phase will include

• inspecting the bridge superstructure and piers (for structural integrity and corrosion),

• routine resurfacing of the asphalted concrete surface,

• stripping, priming, and painting of steel structural sections,

• removing vegetation from the bridge and its basement, and

• winter maintenance to keep it passable.

During all these three phases of the project, there will be impact on the environment, socioeconomic sphere, cultural sphere, and the visual/esthetic sphere.

Most of the impacts, which occurred during the pre-construction and construction phase of a bridge construction, are similar to those occurring during a hydropower dam construction (see Table 2). In this part more attention is put on each impact on the environment and its short explanation.

Impact on physical environment

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