Soft normally consolidated clays are generally too soft for civil works and some kind of improvement needs to be applied. The cost of improvement and the benefits achieved will be critical in the decision to go ahead with soil improvement. A common way to improve soft soil is to remove water from the soil by causing the soil to consolidate under the weight of a surcharge. Generally, embankments on soft soils are instrumented when they are constructed so that the progress of consolidation can be monitored. Settlement plates are often placed at the centre of the embankment, and piezometers placed along the centreline. Other instrumentation such as slope indicators is placed at the toe of the embankment to monitor lateral movement with depth. Consolidation using PVD systems can be accelerated by applying a vacuum to the drains so as to create a greater pressure difference between the water in the drains and the clay.