They could dig a two feet wide bore hole with that twist drill going down six hundred foot this being in the water table would fill with water, an upright coffin placed in the grave between the grass
side covers would be unseen to disperse the water to accommodate the coffin the spinkling of earth by the mourners on top would separate it from the next burial, this would allow ninty nine burials at six foot each leaving the top cover six foot of earth.
In these conditions more space would become available with the decomposition to bury more.
Using this way a six feet by two feet Grave plot would take three times by two square foot, Two hundred an ninety seven coffins

Over the last years I have experienced at a burial the signs of water having been pumped from the new open grave to recieve the coffin, so this method would be the same as now practiced.

A morbid thought but is there an alternative?
What we remember is what happened to the coffin.
Did it Burn at a Cremation?
Did it float in an open grave?
It is how we remember that ending.

RIP