Exactly so. Just use the word 'was', not 'is'. It was a common practice at the time.
The logic was like that: a wet soil “recycles” the corpse and coffin buried in it in apparently 20 years, after which the place is ready for the next burial -> this is the re-use of city cemetery's territory. It would be more correct to say that the land is not sold, but is leased... leased - for a period of 25, 50, or 100+ years.