SMALL DAMS PETITS BARRAGES

c) The decommissioning plan should include the necessary measures to be taken to
guarantee the safety of the area, especially the capacity of outflow of water as well as to
guarantee the stability of permanent structures without causing any adverse impact upstream
and downstream and without affecting the fixed structures which might be in service;
d) The project shall require the processing of an Environmental Impact Evaluation
clearance which varies from case to case;
e) This project should be preapproved by the competent Authority for safety of dams
and reservoirs.
Once the decommissioning project is executed, the competent authority for safety of
dams and reservoirs will carry out an inspection of the site and its area of impact before
issuing the concerned report which will be required for the final approval of the
decommissioning procedure.
In Spain, about 25 decommissioning works have been implemented up to this date. All of
them are small dams with 1 to 8 meters of height.
In the USA over 450 dams have been decommissioned and their experience in this field
should be taken into account by anyone researching the topic.
Decommissioning is often not adequately considered when evaluating dam safety
upgrades, but it is a reality that engineers and dam owners will be facing more and more in the
next few decades.
There are many aspects to a dam decommissioning that must be considered by anyone
interested on the subject, whether it is for the purpose of decommissioning an actual dam or to
set a regulation regarding dam decommissioning. These aspects are thoroughly examined in
the bulletin on decommissioning guidelines, developed by the Operations, Monitoring and
Decommissioning of Dams Committee, that is under publication by the ICOLD.
4.6 CONCLUSION
Formal regulation by Government play an essential role in promoting increased physical
and environmental safety, responding to a social need and requirement. The regulation shall
consider the four main phases regarding a dam: planning-approval, construction, operation
and eventual closure.
Governments must focus on supervision and monitoring of dams, small and large, since
potential losses in lives and property damage caused by flooding are increasing as
development progresses bottomland alongside rivers. Considering the large number of small
dams in each country it is essential to establish a dam risk prioritization criteria, and
concentrate attention and efforts on the high hazard small dams, in a first stage.
It is paramount that the supervision and monitoring activities are conducted with the
necessary skill, according to the size and potential risk of the dam, in a context of clear
assignment of roles and duties of the Owners, Concession Holders and Supervising Authority
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