FLORENCE, Ala. — Dianne O’Neal still lives on the rustic cattle farm that her husband’s family has owned since his great-great-great-grandfather purchased the land in the 1830s. She still stays in a log cabin built from chestnut trees that his ancestors chopped by hand.

But one aspect of the family’s long history here in northern Alabama is not so well preserved: Coffee Cemetery, an overgrown one-acre graveyard where the ancestors of her husband, Edward O’Neal, and their slaves are buried.

That has become a pressing matter in Florence because Walmart plans to build a store right next to the graveyard. The O’Neals’ biggest concern is that nobody knows exactly where their ancestors’ 80 slaves are buried.

The slaves were owned by Gen. John Coffee, a friend of President Andrew Jackson’s and a surveyor who drew the state’s border with Mississippi. And there is archaeological and historical evidence that suggests his slaves’ graves may be precisely where Walmart plans to pave a driveway to the new store.