In this paper the problem of draining a heavy clay layer of low hydraulic conductivity over-lying an impermeable layer is treated mathematically by means of a combined system of pipe and mole drains. The complex potential, the stream functions, and the velocity potential are provided.   New discharge formulas for both tile and mole drains are established.  Formulas for calculating the velocity components at any point are provided.  Effects of the different variables, the top clay cap thickness below drain center ,D, mole drain diameter ,d2, height of water above tile  drain center midway between two successive tile drains, H, mole spacing ,a, and the vertical distance between tile drains and mole drains ,b, are studied.