Wash boring is soil boring test implement by water injection passing drilling rod through borehole with high pressure water pump and flow to chopping bit for soil impingement or soil mastication. Soil was damaged until size of soil is smaller which soil is moved up at the borehole wall by water and flowed down in portable slush that is side of the borehole for coarse grain Soil precipitation and then some water is pumped for water reuse.
This Soil boring test method is necessary for protection damage of borehole wall from casing hammering down into soft clay layer. In case for soil boring is deeper than sand layer which is essential to use bentonite for borehole collapse.
Motorized drilling machine is easy for transposition and installation. You can observe soil layer variation by soil classification such as sand or gravel and color of water overflow from top soil and stickiness or plasticity index of soil layer each soil provoke time that is useful for transfiguration of soil. Soil classification will be difficult, If slush is mixed bentonite.