I am a driller. The work done is to dry out the marshy area by drilling the ground and laying a wick. In the meantime, it allows it to dry out by barking. This is technically correct.They are wicks to allow groundwater to drain rapidly out of the clay soil and increase the rate of its settlement under the new load.There called Wick drains. Its a way for the water in poor soil conditions to be be drained.