Birmingham Council's planning department is yet to make a decision on the proposal but a risk assessment states that "exhumations" may be required if it were approved.
The process could be a gory one, as explained in the site's assessment: "Bacteria from faecal matter and decaying remains may also be present, additional to infectious diseases such as tuberculosis.
"It is possible that anthrax from the use of lamb's wool or equivalent in coffin interiors may also be present."
Some diseases can only be contracted soon after death but there still is a risk.
Local legend claims the pub was a favourite of highwayman Dick Turpin, who is said to be buried nearby.
A spokesman for Marston's said if any remains are found, the appropriate procedures will be followed and the process will be dealt with sensitively.
The 'exhumation' project means the pubco had to advertise to potential relatives of those buried on site in a local newspaper. If not claimed at Phoenix Exhumation - a company specialising in exhumation - remains will be relocated.
The onsite burial ground may also be a source of hazardous gas. These gases include hydrogen sulphide, carbon dioxide and methane.
"These contaminants may pose a risk to site users via ingestion, dermal contact, inhalation pathways and explosion," the assessment continued.
However, the concentrations of these gases reduce over time as the body and materials degrade. As the burial ground was associated with a Baptist church, it was most likely last used in 1850, the assessment added.
Plans to build convenience stores on pub land, often Co-operative branches, can be controversial.
Some licensees worry they'll be damaging to trade – with neighbouring shops selling cheap booze, which draws in customers while valuable car parking spaces are lost.
But new 'pubco' NewRiver Retail submitted 48 planning applications to develop so-called 'surplus' pub land in October.
The firm now owns 360 pubs and claims there is a "clear synergy" between pubs and convenience stores.
A spokesman said: "A neighbourhood or community hub is created where the majority of trips are by foot. Footfall is critical to any retail or hospitality business, and potential customers will be brought right to the doorstep."
But licensees don't always agree. An application has been accepted for a Co-op in the car park of Ty Fry Inn in Rhyl, Wales. Tenant John Locke said he is concerned at the long-term intentions of NewRiver.
"The danger is if they decide it's not viable as a pub any more and close us if trade is down. It would be a disaster for the community because we're the only pub in the village," he said.
Similarly at the Crown, Netherton, West Midlands, an application was accepted despite opposition from publican Robin Wall. He said the application could mean the end of the pub because it will have space for just 11 cars, down from 50.
But not all licensees have such concerns, with some recognising the benefits championed by NewRiver.