Coal mining, especially strip mining, affects the area that is being mined. Characteristically, the material closest to the coal is acidic. After the mining is completed, the land will remain barren unless special precautions are taken to ensure that proper topsoil is used when the area is replanted. Materials other than coal are also brought to the surface in the coal mining process, and these are left as solid wastes. As the coal itself is washed, more waste material is left. Finally, as the coal is burned, the remaining ash is left as a waste product.