The old septic tank was 1000 gallons and the new pressure system with a vaulted pump called for a 1250 gallon tank. First the old tank had to be pumped out, then dug out of the ground and disposed of. With that done the hole had to be enlarged some to put the bigger tank in. I ended up using a polyethlene plastic
tank on this one since there were trees in the way that would have prevented a boom truck from being able to get a concrete tank into the location.