Settlement Tanks

High performance, rapidly deployable settlement tank (also know as a silt trap or a settlement unit) for hire and sale. Effective removal of suspended solids from construction wastewater using lamella clarifiers (inclined plates) providing a large settlement area within a small footprint.

Siltbuster are the UK’s leading supplier of Settlement Tanks (commonly known as Silt Traps) with a hire fleet of mobile Lamella Clarifiers ready for rapid deployment onsite. These high performance settling tanks are designed to remove suspended solids from construction wastewater providing effective silt management/Total Suspended Solids (TSS) removal. Siltbuster mobile clarifiers are robust, skid-mounted, compact and lightweight making them simple to transport, install and operate. The small footprint enables units to be used in the tightest areas, including underground installations.

The Importance of Silt Management

Silt whilst technically referring to a specific grain size (see table on the right) is more often a broad term applied to fine particles of soil carried by water giving it that muddy or dirty discoloration. The most common source of silt pollution is the result of rainwater runoff from topsoil stripped areas of construction sites. When washed off into nearby watercourses, silt pollution is highly visible and easily traceable back to the site. It can travel a long way, causing significant environmental harm including suffocating fish by blocking gills and settling on river beds killing bottom dwelling organisms. There are legal limits for the concentration of suspended solids in discharged water and breaching these is a common reason for construction companies being taken to court and fined.


Why is Particle Size Important?

Most typical soils have the same density (around 2.65 t/m3) however are made up of a variety of particle sizes hence settle at very different rates. Gravel and sand for instance settle at circa 1000m/hr (sink like a rock) yet clay (for which the particles have a very similar density) settle at circa 0.013m/hr. The settlement velocity is proportional to the size of the particle diameter squared. Therefore dependent on the geology of the material, different methods of treatment will be applicable.


Grain Size Sediment Type
< 2 μm Clay
2 μm – 63 μm Silt
63 μm – 2 mm Sand
2 mm – 4 mm Coarse Sand
4 mm – 6 cm Pebbles
6 cm to 25 cm Cobbles
>25cm Boulders

Siltbuster fb50 lamella clarifier
How does a Lamella Clarifier work?

A lamella clarifier uses a gravity based solid/liquid separation over a series of inclined plates in parallel, providing a very large effective settling area for TSS removal. The diagram on the left shows the inlet flow through a feed channel to the base of the plates. The flow is then distributed with each flow diagonally upwards in parallel to the lamella plates. The particles settle on the plates and then accumulate at the bottom of the unit. The clarified liquid leaves over a weir.


Advantages of using a Lamella Clarifier

  • Up to 20 times more efficient than conventional settlement tanks and lagoons resulting in much less space required onsite
  • No energy required
  • Can be used with chemical dosing to improve settling rates
  • Rapidly deployable and easy to operate



Siltbuster have the UK’s largest range of sizes and capabilities of lamella clarifier for both sale and rental suiting most applications. They are used on construction sites as part of the site water management, with typical applications being site runoff treatment; roads and pipelines; drilling and mining; de-silting and dredging; in-river and near-river works. For examples of recent projects see our Case Studies page.

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