The land is firm and valid for digging and burying with no need for building

Q: Some of the residents of Al-Saqa` village in Biljurashi donated a sum of money for the building of graves, and they were thus built as follows: A big hole was dug in firm clayey soil which was then partitioned into several graves by erecting four walls of red bricks for each grave. After leveling the land, a casting of cement and iron was poured over them and an opening was made from the side where the body of a deceased was to be entered. Up until today, the graves are still unused. So, what is the ruling regarding them; is it permissible to bury the dead in these graves or are we to demolish them and restore them to their former state? Please note that we used to dig graves in that solid clayey soil and make Lahd (a crevice on the side of a grave facing the direction faced for prayer), and cover it with bricks and mud and finally dust. We hope that you guide us to that you deem best.

A: If the case is indeed as is mentioned in the question; that the land is firm and valid for digging and burying with no need for building, then you must make the graves as you formerly used to do by digging individual graves with separate Lahds since this is what conforms to the Sunnah (action following the teachings of the Prophet).May Allah grant you success! May peace be upon our Prophet Muhammad, his family, and Companions!