The installation of wick drains on the north end of the Willits Bypass Project is about 50% complete. Wick drains, formally called vertical drains, allow water saturated clay soils to compact, or settle, more efficiently. When fill is brought in to raise the new highway the existing soil will begin to settle. The wick drains will reduce the time for the soil to settle from as long as ten years down to only six months, reducing maintenance costs that would otherwise be needed to repair the highway as it continued to settle for years.
Wick drains do not wick; they are are nicknamed wicks because they look like large oil lamp wicks. They simply allow excess water to move out of the clay layers and move up, or down, to more permeable layers. Little water, if any, will rise to the surface, and if it does it will be collected and properly processed before being used for dust control. Water will only move through the wick drains during the six months the soil is being compacted by the fill.
The north interchange will soon begin to take shape as fill is brought in from the southern end of the bypass project and the wick drains are covered over. See also: Willits Bypass Project – All About Wick Drains