Contaminated Seabed Sediment Stabilisation – Encapsulation Mixer

In-situ – Underwater – Contained – Guaranteed Placement of Liquid Cement Grout

Custom-built, Fully Submersible, Underwater Mass Stabilisation – Encapsulation Mixer
NZ Stirrers Methodology behind our unique design is to encapsulate, contaminated seabed sediment, underwater, In-situ by simply removing 99%++ of the seawater via hydraulicking of this water within the mixing tube to the surface mounted “Sediment/Toxic Fume Filter Unit” prior to adding the Liquid Cement Grout under pressure, down through the centre drive shaft/stem while mixing takes place within the 1.0m square steel encapsulation/mixing tube (Length of mixing tube is pending Project specifications and will vary). This square mixing tube is then withdrawn slowly from the seabed sediment, maintaining Cement Grout delivery and mixing simultaneously until reaching the seabed surface. Delivery of the Cement Grout will exit from the bottom of the Double Flight Mixing Auger, just as it does with a CFA auger (continuous flight auger). This will allow mixing and stabilization right to the very top of the seabed as the steel tube is keeping the seawater out from the stabilizing zone (Inside). If required, you can then cap off the top with grout before fully removing the steel tube from the sediment.

Our unique design has a top shield that allows the excavator driver to place/press down onto/into the seabed letting him/her know that the tube is at full depth of (3.3 metres) into the contaminated, soft seabed sediment. The water release tube allows the water to naturally hydraulic from inside of the mixing tube as it penetrates deeper into the seabed sediment. This allows the water to exit to the surface into the “Sediment/Toxic Fume Filter Unit”. The double flight auger can then be turned a few more times once reaching the bottom (3.3 metres) to squeeze the soft seabed sediment to the top (roof) of the square mixing tube getting the last of the water out from the top inside area through the water release tube. Compressed air is then released into the mixing tube to push the balance of water and fumes up the water release tube to the “Sediment/Toxic Fume Filter Unit” for processing.

Mixer Specifications Guide
100% completely sealed mixer, designed for 100% submerging underwater.
Steel mixing tube – size – 3.3m long x 1.0m x 1.0m square (Custom Designed)
The overall total length of the mixer will be 6.5m long* which includes the mixing tube (3.3m) plus the extension (stem shaft, bearing housings and hydraulic motor) but doesn’t including the hitch in the overall length. (Custom Designed)
Double flight auger with discharge port at the bottom (same as a CFA auger)
Used with Liquid Cement Grout or similar only. Not for Dry Binder use.
Drive motor – Torque starting from – 19Knm of Nominal Rated Torque with 32Knm of peak rated torque up to 50Knm of Nominal Rated Torque.
Hydraulic hosing for Hydraulic motor (to hitch area only) Screw fittings.
Compressed Air inlet/outlet to allow cooling to the Hydraulic Motor chamber.
Compressed Air inlet to evacuate leftover sediment water and toxic fumes within the water release tube to the surface “Sediment/Toxic Fume Filter Unit”
Liquid Grout delivery hose to hitch area only.
Sandblasted and Painted.
1 x water release tube design to allow for easy connection to the separate Barge mounted “Sediment/Toxic Fume Filter Unit” to capture the disturbed sediment from within the mixing tube plus the encapsulated toxic fumes concealed within the contaminated sediment.
Fixed Rotating Hitch for Longreach Excavator or similar (client to supply hitch dimensions). Recommended Excavator Size 40 ton upwards.
The whole setup comes on a 20 foot, “Open Top Shipping Container” with a custom cradle holding the mixer safely in place, laying down. This also allows for easy, safe connecting to the excavator. This allows for easy transporting of the equipment by truck, train or ship to any project location whether Nationally or Internationally.
Sediment/Toxic Fume Filter Unit
This separate unit is used to filter off Seabed sediment disturbed water plus smell/toxic fumes from within the mixing tube.
Sediment Mixing could/would release unwanted smells or even worse, toxic fumes impregnated in the mud/seabed material. By hydraulicking this material (sediment water and smell/toxic fumes) to the surface to a separate sealed tank where the disturbed sediment can be filtered off returning clean water to the harbour and the contaminated sediment can be captured and treated separately, giving 0% disturbance of contaminated seabed sediment. The bad smell/toxic fumes from tar and hydrocarbon odours etc… will be filtered through carbon filters to remove the unwanted smell and or toxic fumes that are or could be present at the time of mixing. This would greatly improve the Health and Safety requirements for staff working on or near the mixing equipment and not to mention the local residents and pedestrians.

NZ Stirrers Limited prides itself in innovative thinking. We have had amazing responses to this design. We literally think outside of the box to come up with the right design for your project. Every mixer is meticulously custom designed.