Long considered an impediment to flood flows, the sediments transported by watercourses are now identified as an essential factor in preserving and restoring the river’s hydromorphological and ecological balance. Consequently, this bedload transport is an essential contributor to achieving good ecological status in watercourses.
Concept
Reservoirs subject to significant sedimentation may require sediment flushing and dredging or removal of sediments.
Expertise
Hydrostadium manages the entire project execution of dredging operations:
sampling strategy proposals,
sediment analyses prior to the works,
clarification of the nature and content of the applications to be submitted for review by the competent government authorities,
assistance in selecting the most appropriate dredging methodology,
monitoring of the dredging operation, etc.
This is why sediment dredging must be carried out according to very specific guidelines
dredging will only be carried out in the event of excessive congestion of the watercourse,
dredging must never be considered on a large scale, but planned by limited and priority sectors,
dredging operations will primarily target the central flow channels and will be limited or even avoided near the banks,
before any dredging operation, it will be determined whether the deposits are not a response to excessive watercourse width and whether its cross-sectional profile is consistent with the hydraulic regime,
in some cases, dredged sludge will not be spread on the banks in order to prevent their enrichment and raising.
This type of work covers
operations involving the simple mobilization of sediments on a very small scale, without removing them from the minor bed of the watercourse
the removal of sediments as part of large-scale watercourse maintenance operations or maintenance work on a structure (for example, dredging dam reservoirs).
What becomes of the sediments
If “in-river management” is not feasible, Hydrostadium assists project owners in identifying potential land-based management routes for sediments : use in road or landscaping projects, recovery through sorting facilities, use in quarry reclamation, agricultural spreading, cement production, or permanent storage.
Discover our Projects
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2020 - 2023
Clearing the bottom outlet of the Jotty Dam (74)
La Vernaz
In 2015, during a flushing operation, debris (mainly trunks, stumps and sediment) formed a blockage in the middle of the Jotty outlet tunnel, 20 metres below the reservoir level.
Main technical...
2016 - 2017
Dredging of the Rioumajou reservoir (65)
Hautes-Pyrénées
Main technical features
Pumping-dilution using a slurry pump with a dilution head and divers (2,400 m3); dry mechanical dredging (6,000 m3 of sediment); manual and mechanized dredging...
2010 / 2013
Dredging of the Membrun reservoir (63)
Thiers
Dredging and physicochemical treatment of the 50,000 m3 of sediment from the reservoir.
Main technical features
Hydraulic and mechanical dredging using a floating excavator and a long-reach...
2011 / 2014
Dredging of the Plan d'Arem reservoir (31)
Arlos
Dredging of 50,000 m3 of sediment following the June 2013 flood
Main technical features
Hydraulic and mechanical dredging using a dragline; hydraulic dredging using a suction dredger; spud...