Environmental and Social Impact Assessment - Gibe III

Gibe III – Environmental and Social Impact Assessment 300 ENV R CS 002 C - A9003099
development on locations with sensitive habitat and wildlife resources. There will also be no effects on
agricultural lands or to settlements.
The following measures are recommended to be taken for the rehabilitation of the quarry areas: reestablishment
of vegetation, restoration of natural water courses, avoidance of flooding of the excavated
areas, achievement of stable slopes, and avoidance of features which would otherwise constitute a risk to
health and safety or a source of environmental pollution. Quarry faces and excavations be made safe and
buildings, plant, equipment and debris and stockpiles of material be removed from the areas.
7.6.2 Spoil and Waste Material Disposal Areas
The construction of Gibe III hydropower scheme is expected to generate large quantities of spoil material
and these spoils will need to be disposed off. The potential environmental concerns related to the spoil
disposal include loss of productive land, grazing land and natural vegetation, interference with natural
drainage, increase in erosion and sediment deposition, increase in slope instability and visual alternation of
landscapes quality. There is a possibility of soil erosion and adverse aesthetic impact if spoils are not
properly placed and rehabilitated
Spoil disposal activities should be planned to be executed in a manner which minimizes these potential
damage to environment and maintains stability during all stages of placement and when the site is in its final
form. For disposal of waste soil and rock, both the placement of the materials and the rehabilitation methods
are important. Therefore, to mitigate and minimize the impacts of spoil disposal on the local environment the
following mitigation measures are recommended:
• Locate spoil disposal sites as much as possible in unproductive land and outside flood conveyance
areas with preference being given to backfilling quarry and borrow sites which have been developed
by the contracted. However, spoil disposal sites to be located in flood storage areas only in those
cases where the studies have determined that the impact is not significant;
• Locate disposal sites in areas of land, which, prior to the commencement of the construction works,
were not used for agricultural purposes or designated for agricultural purposes;
• For each disposal site incorporate the most appropriate stabilization techniques;
• Placement and rehabilitation of spoils and waste be executed with sensitivity to topographic and
visual aspects and in such a way that the disposal areas enhance rather than detract visual quality of
the route. After the completion of construction, most of the disturbed areas will require some recontouring
to encourage natural drainage pattern, improve slope stability, and mimic the original
shape of the slope. The amount of grading and re-contouring will depend heavily on the type of
disturbance and the quantity of material deposited. Re-contouring will also consider drainage such
that water neither pools on the site, nor flows through with sufficient velocity to erode soils and
overburden;
• Adopt restoration measures to reinstate the site for its previous use. For this, soil excavated during
construction be stockpiled separately and used for landscaping and restoration of work areas. Topsoil
stockpiles are deep ripped to provide for moisture retention and re-growth of local trees and bushes.
However, it is also recommended to prepare a site environmental management plan for each proposed spoil
disposal sites and this plan should include environmental studies and consultation to assess the potential
impacts of each proposed spoil disposal sites and the recommend site specific management measures. The
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