How deep is the coffin buried in Feng Shui?

There should not be many coffins buried in the countryside now, and they have all been changed into urns. Coffins vary in size, and the depth does not exceed1.98m.. Don't put stones like marble under the coffin, it will cut off the geomagnetic field. The hole depth of the urn is 88 cm, and the clear width and length of the single hole and double hole are 40 cm and 66 cm, respectively. The middle of the double holes is made of a brick with the width of horizontal brick, which is covered with slate or cement board.