Spolana - chemical waste disposal wall
CZECH REPUBLIC, 1996
Ecosol containment wall and dynamic compaction.
Nowadays, new and original geotechnical applications are required to clear polluted sites in the Czech Republic. The Spolana toxic chemical waste disposal landfill, at Neratovice, is an example of a site requiring remediation by the privatised Spolana company.
Pollution was mainly due to PAH, cyanides, organochlorines, mercury and pesticides.
The following method was used:
- isolating the existing landfill, by building an ECOSOL containment wall,
- increasing landfill capacity by creating a new ground-level landfill after compaction of existing underlying waste and construction of new dykes.
ECOSOL containment wall
Built using a KS 3000 hydraulic grab, between 11 and 20m in depth, and keyed 1 m-deep into the underlying marl. Required permeability was lower than 10-10 m/sec. This higher-than average requirement was reached thanks to the use of Soletanche Bachy patented Ecosol slurry. Checked non stop during operation, average permeability of site samples reached about 3 x 10-11 m/sec, with a maximum of 9 x 10-11 m/sec and a minimum of 2 x 10-12 m/sec. Water tests on core samples confirmed these excellent values.
Specifications required acceptable differential settlings lower than 1/400, for total settling lower than 100mm, and new landfill loading capacity exceeding 0.2 MPa. ln order to meet this target, after penetrometer survey, waste quality needed to be improved on at least a 10m thickness. Consolidation was obtained by dropping a 15-t hammer, on a 10-m mesh, from a height of 20m. Two penetrometer tests, and the construction of a loading dyke, proved that targets had been met. The whole works were controlled by chemical engineers. They checked that compaction did not cause toxic gas fumes. Luckily, it did not happen. Later, the use of a Glötzl horizontal «inclinometer» enabled to validate all chosen hypothesis and helped to optimise new landfill capacity.
Groundwater is one of the most complex issues to be resolved in geotechnics. During the start phase of a project, the proper techniques have to be chosen for building any cut-off walls that might be required, pumping (wells, filter points, etc.) and monitoring (piezometers) resources.
Soletanche Bachy, and its subsidiary Solenvironment, provide solutions for pollution issues, involving, for example: inertisation of waste, rehabilitation and treatment of polluted sites, cleaning of discharge to required environmental control levels, construction of waste storage facilities, protection of groundwater.
Through his subsidiary Sol Environment, Soletanche Bachy provides solutions to various pollution problems: stabilisation of waste, rehabilitation and treatment of polluted sites, cleaning of discharge to required environmental control levels, construction of waste storage facilities, protection of the water table.
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