Single-phase-method

The construction of a 1-phase-wall comprises the following steps: The first step involves excavation work, optionally with a grab or cutter, whereby the stabilizing slurry consists of a self-hardening bentonite-cement slurry. Subsequently, sheet pile walls or beams can be installed as structural element in the not yet hardened slurry.

In this process the support fluid, which is pumped into the trench during the excavation stage, consists of a bentonite-cement slurry, that remains in the trench after completion of the excavation and forms a self-hardening barrier inside the trench.

Double-phase-method

The construction of a 2-phase-wall comprises the following steps: The first step involves excavating a defined sub area (panel) using suitable excavation equipment, such as a grab or cutter under stabilizing bentonite slurry and/or polymer. This is followed by the regeneration of the stabilizing bentonite slurry and/or polymer. The final step involves concreting using the tremie pipe. For sealing purposes using a two-phase cut-off wall, a placement of a reinforce- ment cage is not necessary. The support fluid is subse- quently cleaned and then replaced in a second phase by the actual barrier material (e.g. plastic concrete) which is placed in the trench using the tremie method.

Slurry handling

In general: The required slurry is pumped through installed lines from the mixing area to the open trench. Using cutter: The mixture of soil material and slurry is pumped through permanently installed lines to the desanding plant. There, the soil material is separated from the slurry by means of vibrating screens and cyclones. The cleaned slurry is then returned to the excavation trench. During concreting the stabilizing slurry displaced from the trench is also pumped out and cleaned. Using grab: Each time the grab is pulled out of the open panel, the mixture of soil and slurry is usually unloaded onto skips and transported to an intermediate storage facility.