Overview

EKG In Situ Dewatering

EKG In Situ dewatering

EKG materials formed as prefabricated vertical drains can increase the speed of consolidation of soft ground by employing electroosmotic flow. This may be used for the purpose of dewatering materials for subsequent excavation or in situ ground improvement prior to developing the site.

In fine grained soils, such as tailings and sludges, flow rates induced by electroosmosis can be 3 - 4 orders of magnitude higher than equivalent hydraulic flow rates.

EKG materials, in this application, are constructed as either vertically oriented modular length rigid tubes or a flexible composite of variable length, which can be inserted into the ground by lance or mandrill. The treatment can reduce consolidation time by 50 – 80% compared to conventional wick drains and does not require the addition of a surcharge.

A typical application for EKG technology is consolidation/dewatering of lagooned materials such as mine wastes of sewage sludges. These materials tend to have high water contents and low hydraulic conductivities (both of which favour electroosmosis). An approach is illustrated below:

Illustration of electrode installation in an EKG lagoon consolidation project

Cross section illustration of lagoon after EKG consolidation

Consolidated lagoon after infill

The technique is applicable in situation where conventional approaches are impractical or uneconomic. These may include:

• Wick drains + surcharge

• Cementitious stabilisation

• Dilute and dewater

Each potential application requires individual consideration, the variables to consider include:

1. Target strength (water/solids content)

2. Speed of treatment

3. Cost

The treatment design can accommodate the above objectives by varying the number of installed electrodes, the applied voltage and the duration of treatment .
Examples of the use of this technique are the remediation of historic lagoons e.g. tailings or industrial treatment sludges. Please see our download page for examples of the use of this technique.