Get a few bags of slaked lime ( garden store) strip bodies and put lime on them will help the decay, if contagion you will be dealing with more than one mass grave only fast way when everyone sick.
or you can learn a lesson from news and use drums and caustic soda /lye if the mexican cartel disposed of hundreds of bodies that way so can you in a few days nothing but slime and a few bones all the other is is dissolved. again no clothes
burning works but requires a lot of fuel unless you have stockpiles of wood you dont need may over tax resources if burning one at a time in time of potential mass sickness.
Tolik think about how long man has been on this earth and think… everywhere you can dig probably has been used at some point especially areas where most major cities are. In some European/asian countries you rent space for set time then they exhume and put bones in Ossuary.